linux/fs/ext4/inode.c
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   1/*
   2 *  linux/fs/ext4/inode.c
   3 *
   4 * Copyright (C) 1992, 1993, 1994, 1995
   5 * Remy Card (card@masi.ibp.fr)
   6 * Laboratoire MASI - Institut Blaise Pascal
   7 * Universite Pierre et Marie Curie (Paris VI)
   8 *
   9 *  from
  10 *
  11 *  linux/fs/minix/inode.c
  12 *
  13 *  Copyright (C) 1991, 1992  Linus Torvalds
  14 *
  15 *  64-bit file support on 64-bit platforms by Jakub Jelinek
  16 *      (jj@sunsite.ms.mff.cuni.cz)
  17 *
  18 *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
  19 */
  20
  21#include <linux/fs.h>
  22#include <linux/time.h>
  23#include <linux/jbd2.h>
  24#include <linux/highuid.h>
  25#include <linux/pagemap.h>
  26#include <linux/quotaops.h>
  27#include <linux/string.h>
  28#include <linux/buffer_head.h>
  29#include <linux/writeback.h>
  30#include <linux/pagevec.h>
  31#include <linux/mpage.h>
  32#include <linux/namei.h>
  33#include <linux/uio.h>
  34#include <linux/bio.h>
  35#include <linux/workqueue.h>
  36#include <linux/kernel.h>
  37#include <linux/printk.h>
  38#include <linux/slab.h>
  39#include <linux/ratelimit.h>
  40
  41#include "ext4_jbd2.h"
  42#include "xattr.h"
  43#include "acl.h"
  44#include "truncate.h"
  45
  46#include <trace/events/ext4.h>
  47
  48#define MPAGE_DA_EXTENT_TAIL 0x01
  49
  50static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
  51                              struct ext4_inode_info *ei)
  52{
  53        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
  54        __u16 csum_lo;
  55        __u16 csum_hi = 0;
  56        __u32 csum;
  57
  58        csum_lo = raw->i_checksum_lo;
  59        raw->i_checksum_lo = 0;
  60        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
  61            EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
  62                csum_hi = raw->i_checksum_hi;
  63                raw->i_checksum_hi = 0;
  64        }
  65
  66        csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw,
  67                           EXT4_INODE_SIZE(inode->i_sb));
  68
  69        raw->i_checksum_lo = csum_lo;
  70        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
  71            EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
  72                raw->i_checksum_hi = csum_hi;
  73
  74        return csum;
  75}
  76
  77static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
  78                                  struct ext4_inode_info *ei)
  79{
  80        __u32 provided, calculated;
  81
  82        if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
  83            cpu_to_le32(EXT4_OS_LINUX) ||
  84            !EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
  85                EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  86                return 1;
  87
  88        provided = le16_to_cpu(raw->i_checksum_lo);
  89        calculated = ext4_inode_csum(inode, raw, ei);
  90        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
  91            EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
  92                provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
  93        else
  94                calculated &= 0xFFFF;
  95
  96        return provided == calculated;
  97}
  98
  99static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
 100                                struct ext4_inode_info *ei)
 101{
 102        __u32 csum;
 103
 104        if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
 105            cpu_to_le32(EXT4_OS_LINUX) ||
 106            !EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
 107                EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 108                return;
 109
 110        csum = ext4_inode_csum(inode, raw, ei);
 111        raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
 112        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
 113            EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
 114                raw->i_checksum_hi = cpu_to_le16(csum >> 16);
 115}
 116
 117static inline int ext4_begin_ordered_truncate(struct inode *inode,
 118                                              loff_t new_size)
 119{
 120        trace_ext4_begin_ordered_truncate(inode, new_size);
 121        /*
 122         * If jinode is zero, then we never opened the file for
 123         * writing, so there's no need to call
 124         * jbd2_journal_begin_ordered_truncate() since there's no
 125         * outstanding writes we need to flush.
 126         */
 127        if (!EXT4_I(inode)->jinode)
 128                return 0;
 129        return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
 130                                                   EXT4_I(inode)->jinode,
 131                                                   new_size);
 132}
 133
 134static void ext4_invalidatepage(struct page *page, unsigned long offset);
 135static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
 136                                   struct buffer_head *bh_result, int create);
 137static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
 138static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
 139static int __ext4_journalled_writepage(struct page *page, unsigned int len);
 140static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
 141static int ext4_discard_partial_page_buffers_no_lock(handle_t *handle,
 142                struct inode *inode, struct page *page, loff_t from,
 143                loff_t length, int flags);
 144
 145/*
 146 * Test whether an inode is a fast symlink.
 147 */
 148static int ext4_inode_is_fast_symlink(struct inode *inode)
 149{
 150        int ea_blocks = EXT4_I(inode)->i_file_acl ?
 151                (inode->i_sb->s_blocksize >> 9) : 0;
 152
 153        return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
 154}
 155
 156/*
 157 * Restart the transaction associated with *handle.  This does a commit,
 158 * so before we call here everything must be consistently dirtied against
 159 * this transaction.
 160 */
 161int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
 162                                 int nblocks)
 163{
 164        int ret;
 165
 166        /*
 167         * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
 168         * moment, get_block can be called only for blocks inside i_size since
 169         * page cache has been already dropped and writes are blocked by
 170         * i_mutex. So we can safely drop the i_data_sem here.
 171         */
 172        BUG_ON(EXT4_JOURNAL(inode) == NULL);
 173        jbd_debug(2, "restarting handle %p\n", handle);
 174        up_write(&EXT4_I(inode)->i_data_sem);
 175        ret = ext4_journal_restart(handle, nblocks);
 176        down_write(&EXT4_I(inode)->i_data_sem);
 177        ext4_discard_preallocations(inode);
 178
 179        return ret;
 180}
 181
 182/*
 183 * Called at the last iput() if i_nlink is zero.
 184 */
 185void ext4_evict_inode(struct inode *inode)
 186{
 187        handle_t *handle;
 188        int err;
 189
 190        trace_ext4_evict_inode(inode);
 191
 192        ext4_ioend_wait(inode);
 193
 194        if (inode->i_nlink) {
 195                /*
 196                 * When journalling data dirty buffers are tracked only in the
 197                 * journal. So although mm thinks everything is clean and
 198                 * ready for reaping the inode might still have some pages to
 199                 * write in the running transaction or waiting to be
 200                 * checkpointed. Thus calling jbd2_journal_invalidatepage()
 201                 * (via truncate_inode_pages()) to discard these buffers can
 202                 * cause data loss. Also even if we did not discard these
 203                 * buffers, we would have no way to find them after the inode
 204                 * is reaped and thus user could see stale data if he tries to
 205                 * read them before the transaction is checkpointed. So be
 206                 * careful and force everything to disk here... We use
 207                 * ei->i_datasync_tid to store the newest transaction
 208                 * containing inode's data.
 209                 *
 210                 * Note that directories do not have this problem because they
 211                 * don't use page cache.
 212                 */
 213                if (ext4_should_journal_data(inode) &&
 214                    (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
 215                        journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
 216                        tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
 217
 218                        jbd2_log_start_commit(journal, commit_tid);
 219                        jbd2_log_wait_commit(journal, commit_tid);
 220                        filemap_write_and_wait(&inode->i_data);
 221                }
 222                truncate_inode_pages(&inode->i_data, 0);
 223                goto no_delete;
 224        }
 225
 226        if (!is_bad_inode(inode))
 227                dquot_initialize(inode);
 228
 229        if (ext4_should_order_data(inode))
 230                ext4_begin_ordered_truncate(inode, 0);
 231        truncate_inode_pages(&inode->i_data, 0);
 232
 233        if (is_bad_inode(inode))
 234                goto no_delete;
 235
 236        /*
 237         * Protect us against freezing - iput() caller didn't have to have any
 238         * protection against it
 239         */
 240        sb_start_intwrite(inode->i_sb);
 241        handle = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)+3);
 242        if (IS_ERR(handle)) {
 243                ext4_std_error(inode->i_sb, PTR_ERR(handle));
 244                /*
 245                 * If we're going to skip the normal cleanup, we still need to
 246                 * make sure that the in-core orphan linked list is properly
 247                 * cleaned up.
 248                 */
 249                ext4_orphan_del(NULL, inode);
 250                sb_end_intwrite(inode->i_sb);
 251                goto no_delete;
 252        }
 253
 254        if (IS_SYNC(inode))
 255                ext4_handle_sync(handle);
 256        inode->i_size = 0;
 257        err = ext4_mark_inode_dirty(handle, inode);
 258        if (err) {
 259                ext4_warning(inode->i_sb,
 260                             "couldn't mark inode dirty (err %d)", err);
 261                goto stop_handle;
 262        }
 263        if (inode->i_blocks)
 264                ext4_truncate(inode);
 265
 266        /*
 267         * ext4_ext_truncate() doesn't reserve any slop when it
 268         * restarts journal transactions; therefore there may not be
 269         * enough credits left in the handle to remove the inode from
 270         * the orphan list and set the dtime field.
 271         */
 272        if (!ext4_handle_has_enough_credits(handle, 3)) {
 273                err = ext4_journal_extend(handle, 3);
 274                if (err > 0)
 275                        err = ext4_journal_restart(handle, 3);
 276                if (err != 0) {
 277                        ext4_warning(inode->i_sb,
 278                                     "couldn't extend journal (err %d)", err);
 279                stop_handle:
 280                        ext4_journal_stop(handle);
 281                        ext4_orphan_del(NULL, inode);
 282                        sb_end_intwrite(inode->i_sb);
 283                        goto no_delete;
 284                }
 285        }
 286
 287        /*
 288         * Kill off the orphan record which ext4_truncate created.
 289         * AKPM: I think this can be inside the above `if'.
 290         * Note that ext4_orphan_del() has to be able to cope with the
 291         * deletion of a non-existent orphan - this is because we don't
 292         * know if ext4_truncate() actually created an orphan record.
 293         * (Well, we could do this if we need to, but heck - it works)
 294         */
 295        ext4_orphan_del(handle, inode);
 296        EXT4_I(inode)->i_dtime  = get_seconds();
 297
 298        /*
 299         * One subtle ordering requirement: if anything has gone wrong
 300         * (transaction abort, IO errors, whatever), then we can still
 301         * do these next steps (the fs will already have been marked as
 302         * having errors), but we can't free the inode if the mark_dirty
 303         * fails.
 304         */
 305        if (ext4_mark_inode_dirty(handle, inode))
 306                /* If that failed, just do the required in-core inode clear. */
 307                ext4_clear_inode(inode);
 308        else
 309                ext4_free_inode(handle, inode);
 310        ext4_journal_stop(handle);
 311        sb_end_intwrite(inode->i_sb);
 312        return;
 313no_delete:
 314        ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
 315}
 316
 317#ifdef CONFIG_QUOTA
 318qsize_t *ext4_get_reserved_space(struct inode *inode)
 319{
 320        return &EXT4_I(inode)->i_reserved_quota;
 321}
 322#endif
 323
 324/*
 325 * Calculate the number of metadata blocks need to reserve
 326 * to allocate a block located at @lblock
 327 */
 328static int ext4_calc_metadata_amount(struct inode *inode, ext4_lblk_t lblock)
 329{
 330        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
 331                return ext4_ext_calc_metadata_amount(inode, lblock);
 332
 333        return ext4_ind_calc_metadata_amount(inode, lblock);
 334}
 335
 336/*
 337 * Called with i_data_sem down, which is important since we can call
 338 * ext4_discard_preallocations() from here.
 339 */
 340void ext4_da_update_reserve_space(struct inode *inode,
 341                                        int used, int quota_claim)
 342{
 343        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 344        struct ext4_inode_info *ei = EXT4_I(inode);
 345
 346        spin_lock(&ei->i_block_reservation_lock);
 347        trace_ext4_da_update_reserve_space(inode, used, quota_claim);
 348        if (unlikely(used > ei->i_reserved_data_blocks)) {
 349                ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, used %d "
 350                         "with only %d reserved data blocks",
 351                         __func__, inode->i_ino, used,
 352                         ei->i_reserved_data_blocks);
 353                WARN_ON(1);
 354                used = ei->i_reserved_data_blocks;
 355        }
 356
 357        if (unlikely(ei->i_allocated_meta_blocks > ei->i_reserved_meta_blocks)) {
 358                ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, allocated %d "
 359                         "with only %d reserved metadata blocks\n", __func__,
 360                         inode->i_ino, ei->i_allocated_meta_blocks,
 361                         ei->i_reserved_meta_blocks);
 362                WARN_ON(1);
 363                ei->i_allocated_meta_blocks = ei->i_reserved_meta_blocks;
 364        }
 365
 366        /* Update per-inode reservations */
 367        ei->i_reserved_data_blocks -= used;
 368        ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
 369        percpu_counter_sub(&sbi->s_dirtyclusters_counter,
 370                           used + ei->i_allocated_meta_blocks);
 371        ei->i_allocated_meta_blocks = 0;
 372
 373        if (ei->i_reserved_data_blocks == 0) {
 374                /*
 375                 * We can release all of the reserved metadata blocks
 376                 * only when we have written all of the delayed
 377                 * allocation blocks.
 378                 */
 379                percpu_counter_sub(&sbi->s_dirtyclusters_counter,
 380                                   ei->i_reserved_meta_blocks);
 381                ei->i_reserved_meta_blocks = 0;
 382                ei->i_da_metadata_calc_len = 0;
 383        }
 384        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 385
 386        /* Update quota subsystem for data blocks */
 387        if (quota_claim)
 388                dquot_claim_block(inode, EXT4_C2B(sbi, used));
 389        else {
 390                /*
 391                 * We did fallocate with an offset that is already delayed
 392                 * allocated. So on delayed allocated writeback we should
 393                 * not re-claim the quota for fallocated blocks.
 394                 */
 395                dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
 396        }
 397
 398        /*
 399         * If we have done all the pending block allocations and if
 400         * there aren't any writers on the inode, we can discard the
 401         * inode's preallocations.
 402         */
 403        if ((ei->i_reserved_data_blocks == 0) &&
 404            (atomic_read(&inode->i_writecount) == 0))
 405                ext4_discard_preallocations(inode);
 406}
 407
 408static int __check_block_validity(struct inode *inode, const char *func,
 409                                unsigned int line,
 410                                struct ext4_map_blocks *map)
 411{
 412        if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
 413                                   map->m_len)) {
 414                ext4_error_inode(inode, func, line, map->m_pblk,
 415                                 "lblock %lu mapped to illegal pblock "
 416                                 "(length %d)", (unsigned long) map->m_lblk,
 417                                 map->m_len);
 418                return -EIO;
 419        }
 420        return 0;
 421}
 422
 423#define check_block_validity(inode, map)        \
 424        __check_block_validity((inode), __func__, __LINE__, (map))
 425
 426/*
 427 * Return the number of contiguous dirty pages in a given inode
 428 * starting at page frame idx.
 429 */
 430static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
 431                                    unsigned int max_pages)
 432{
 433        struct address_space *mapping = inode->i_mapping;
 434        pgoff_t index;
 435        struct pagevec pvec;
 436        pgoff_t num = 0;
 437        int i, nr_pages, done = 0;
 438
 439        if (max_pages == 0)
 440                return 0;
 441        pagevec_init(&pvec, 0);
 442        while (!done) {
 443                index = idx;
 444                nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 445                                              PAGECACHE_TAG_DIRTY,
 446                                              (pgoff_t)PAGEVEC_SIZE);
 447                if (nr_pages == 0)
 448                        break;
 449                for (i = 0; i < nr_pages; i++) {
 450                        struct page *page = pvec.pages[i];
 451                        struct buffer_head *bh, *head;
 452
 453                        lock_page(page);
 454                        if (unlikely(page->mapping != mapping) ||
 455                            !PageDirty(page) ||
 456                            PageWriteback(page) ||
 457                            page->index != idx) {
 458                                done = 1;
 459                                unlock_page(page);
 460                                break;
 461                        }
 462                        if (page_has_buffers(page)) {
 463                                bh = head = page_buffers(page);
 464                                do {
 465                                        if (!buffer_delay(bh) &&
 466                                            !buffer_unwritten(bh))
 467                                                done = 1;
 468                                        bh = bh->b_this_page;
 469                                } while (!done && (bh != head));
 470                        }
 471                        unlock_page(page);
 472                        if (done)
 473                                break;
 474                        idx++;
 475                        num++;
 476                        if (num >= max_pages) {
 477                                done = 1;
 478                                break;
 479                        }
 480                }
 481                pagevec_release(&pvec);
 482        }
 483        return num;
 484}
 485
 486/*
 487 * Sets the BH_Da_Mapped bit on the buffer heads corresponding to the given map.
 488 */
 489static void set_buffers_da_mapped(struct inode *inode,
 490                                   struct ext4_map_blocks *map)
 491{
 492        struct address_space *mapping = inode->i_mapping;
 493        struct pagevec pvec;
 494        int i, nr_pages;
 495        pgoff_t index, end;
 496
 497        index = map->m_lblk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
 498        end = (map->m_lblk + map->m_len - 1) >>
 499                (PAGE_CACHE_SHIFT - inode->i_blkbits);
 500
 501        pagevec_init(&pvec, 0);
 502        while (index <= end) {
 503                nr_pages = pagevec_lookup(&pvec, mapping, index,
 504                                          min(end - index + 1,
 505                                              (pgoff_t)PAGEVEC_SIZE));
 506                if (nr_pages == 0)
 507                        break;
 508                for (i = 0; i < nr_pages; i++) {
 509                        struct page *page = pvec.pages[i];
 510                        struct buffer_head *bh, *head;
 511
 512                        if (unlikely(page->mapping != mapping) ||
 513                            !PageDirty(page))
 514                                break;
 515
 516                        if (page_has_buffers(page)) {
 517                                bh = head = page_buffers(page);
 518                                do {
 519                                        set_buffer_da_mapped(bh);
 520                                        bh = bh->b_this_page;
 521                                } while (bh != head);
 522                        }
 523                        index++;
 524                }
 525                pagevec_release(&pvec);
 526        }
 527}
 528
 529/*
 530 * The ext4_map_blocks() function tries to look up the requested blocks,
 531 * and returns if the blocks are already mapped.
 532 *
 533 * Otherwise it takes the write lock of the i_data_sem and allocate blocks
 534 * and store the allocated blocks in the result buffer head and mark it
 535 * mapped.
 536 *
 537 * If file type is extents based, it will call ext4_ext_map_blocks(),
 538 * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
 539 * based files
 540 *
 541 * On success, it returns the number of blocks being mapped or allocate.
 542 * if create==0 and the blocks are pre-allocated and uninitialized block,
 543 * the result buffer head is unmapped. If the create ==1, it will make sure
 544 * the buffer head is mapped.
 545 *
 546 * It returns 0 if plain look up failed (blocks have not been allocated), in
 547 * that case, buffer head is unmapped
 548 *
 549 * It returns the error in case of allocation failure.
 550 */
 551int ext4_map_blocks(handle_t *handle, struct inode *inode,
 552                    struct ext4_map_blocks *map, int flags)
 553{
 554        int retval;
 555
 556        map->m_flags = 0;
 557        ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
 558                  "logical block %lu\n", inode->i_ino, flags, map->m_len,
 559                  (unsigned long) map->m_lblk);
 560        /*
 561         * Try to see if we can get the block without requesting a new
 562         * file system block.
 563         */
 564        if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
 565                down_read((&EXT4_I(inode)->i_data_sem));
 566        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
 567                retval = ext4_ext_map_blocks(handle, inode, map, flags &
 568                                             EXT4_GET_BLOCKS_KEEP_SIZE);
 569        } else {
 570                retval = ext4_ind_map_blocks(handle, inode, map, flags &
 571                                             EXT4_GET_BLOCKS_KEEP_SIZE);
 572        }
 573        if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
 574                up_read((&EXT4_I(inode)->i_data_sem));
 575
 576        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
 577                int ret = check_block_validity(inode, map);
 578                if (ret != 0)
 579                        return ret;
 580        }
 581
 582        /* If it is only a block(s) look up */
 583        if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
 584                return retval;
 585
 586        /*
 587         * Returns if the blocks have already allocated
 588         *
 589         * Note that if blocks have been preallocated
 590         * ext4_ext_get_block() returns the create = 0
 591         * with buffer head unmapped.
 592         */
 593        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
 594                return retval;
 595
 596        /*
 597         * When we call get_blocks without the create flag, the
 598         * BH_Unwritten flag could have gotten set if the blocks
 599         * requested were part of a uninitialized extent.  We need to
 600         * clear this flag now that we are committed to convert all or
 601         * part of the uninitialized extent to be an initialized
 602         * extent.  This is because we need to avoid the combination
 603         * of BH_Unwritten and BH_Mapped flags being simultaneously
 604         * set on the buffer_head.
 605         */
 606        map->m_flags &= ~EXT4_MAP_UNWRITTEN;
 607
 608        /*
 609         * New blocks allocate and/or writing to uninitialized extent
 610         * will possibly result in updating i_data, so we take
 611         * the write lock of i_data_sem, and call get_blocks()
 612         * with create == 1 flag.
 613         */
 614        down_write((&EXT4_I(inode)->i_data_sem));
 615
 616        /*
 617         * if the caller is from delayed allocation writeout path
 618         * we have already reserved fs blocks for allocation
 619         * let the underlying get_block() function know to
 620         * avoid double accounting
 621         */
 622        if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
 623                ext4_set_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
 624        /*
 625         * We need to check for EXT4 here because migrate
 626         * could have changed the inode type in between
 627         */
 628        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
 629                retval = ext4_ext_map_blocks(handle, inode, map, flags);
 630        } else {
 631                retval = ext4_ind_map_blocks(handle, inode, map, flags);
 632
 633                if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
 634                        /*
 635                         * We allocated new blocks which will result in
 636                         * i_data's format changing.  Force the migrate
 637                         * to fail by clearing migrate flags
 638                         */
 639                        ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 640                }
 641
 642                /*
 643                 * Update reserved blocks/metadata blocks after successful
 644                 * block allocation which had been deferred till now. We don't
 645                 * support fallocate for non extent files. So we can update
 646                 * reserve space here.
 647                 */
 648                if ((retval > 0) &&
 649                        (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
 650                        ext4_da_update_reserve_space(inode, retval, 1);
 651        }
 652        if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
 653                ext4_clear_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
 654
 655                /* If we have successfully mapped the delayed allocated blocks,
 656                 * set the BH_Da_Mapped bit on them. Its important to do this
 657                 * under the protection of i_data_sem.
 658                 */
 659                if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
 660                        set_buffers_da_mapped(inode, map);
 661        }
 662
 663        up_write((&EXT4_I(inode)->i_data_sem));
 664        if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
 665                int ret = check_block_validity(inode, map);
 666                if (ret != 0)
 667                        return ret;
 668        }
 669        return retval;
 670}
 671
 672/* Maximum number of blocks we map for direct IO at once. */
 673#define DIO_MAX_BLOCKS 4096
 674
 675static int _ext4_get_block(struct inode *inode, sector_t iblock,
 676                           struct buffer_head *bh, int flags)
 677{
 678        handle_t *handle = ext4_journal_current_handle();
 679        struct ext4_map_blocks map;
 680        int ret = 0, started = 0;
 681        int dio_credits;
 682
 683        map.m_lblk = iblock;
 684        map.m_len = bh->b_size >> inode->i_blkbits;
 685
 686        if (flags && !handle) {
 687                /* Direct IO write... */
 688                if (map.m_len > DIO_MAX_BLOCKS)
 689                        map.m_len = DIO_MAX_BLOCKS;
 690                dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
 691                handle = ext4_journal_start(inode, dio_credits);
 692                if (IS_ERR(handle)) {
 693                        ret = PTR_ERR(handle);
 694                        return ret;
 695                }
 696                started = 1;
 697        }
 698
 699        ret = ext4_map_blocks(handle, inode, &map, flags);
 700        if (ret > 0) {
 701                map_bh(bh, inode->i_sb, map.m_pblk);
 702                bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
 703                bh->b_size = inode->i_sb->s_blocksize * map.m_len;
 704                ret = 0;
 705        }
 706        if (started)
 707                ext4_journal_stop(handle);
 708        return ret;
 709}
 710
 711int ext4_get_block(struct inode *inode, sector_t iblock,
 712                   struct buffer_head *bh, int create)
 713{
 714        return _ext4_get_block(inode, iblock, bh,
 715                               create ? EXT4_GET_BLOCKS_CREATE : 0);
 716}
 717
 718/*
 719 * `handle' can be NULL if create is zero
 720 */
 721struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
 722                                ext4_lblk_t block, int create, int *errp)
 723{
 724        struct ext4_map_blocks map;
 725        struct buffer_head *bh;
 726        int fatal = 0, err;
 727
 728        J_ASSERT(handle != NULL || create == 0);
 729
 730        map.m_lblk = block;
 731        map.m_len = 1;
 732        err = ext4_map_blocks(handle, inode, &map,
 733                              create ? EXT4_GET_BLOCKS_CREATE : 0);
 734
 735        /* ensure we send some value back into *errp */
 736        *errp = 0;
 737
 738        if (err < 0)
 739                *errp = err;
 740        if (err <= 0)
 741                return NULL;
 742
 743        bh = sb_getblk(inode->i_sb, map.m_pblk);
 744        if (!bh) {
 745                *errp = -EIO;
 746                return NULL;
 747        }
 748        if (map.m_flags & EXT4_MAP_NEW) {
 749                J_ASSERT(create != 0);
 750                J_ASSERT(handle != NULL);
 751
 752                /*
 753                 * Now that we do not always journal data, we should
 754                 * keep in mind whether this should always journal the
 755                 * new buffer as metadata.  For now, regular file
 756                 * writes use ext4_get_block instead, so it's not a
 757                 * problem.
 758                 */
 759                lock_buffer(bh);
 760                BUFFER_TRACE(bh, "call get_create_access");
 761                fatal = ext4_journal_get_create_access(handle, bh);
 762                if (!fatal && !buffer_uptodate(bh)) {
 763                        memset(bh->b_data, 0, inode->i_sb->s_blocksize);
 764                        set_buffer_uptodate(bh);
 765                }
 766                unlock_buffer(bh);
 767                BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
 768                err = ext4_handle_dirty_metadata(handle, inode, bh);
 769                if (!fatal)
 770                        fatal = err;
 771        } else {
 772                BUFFER_TRACE(bh, "not a new buffer");
 773        }
 774        if (fatal) {
 775                *errp = fatal;
 776                brelse(bh);
 777                bh = NULL;
 778        }
 779        return bh;
 780}
 781
 782struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
 783                               ext4_lblk_t block, int create, int *err)
 784{
 785        struct buffer_head *bh;
 786
 787        bh = ext4_getblk(handle, inode, block, create, err);
 788        if (!bh)
 789                return bh;
 790        if (buffer_uptodate(bh))
 791                return bh;
 792        ll_rw_block(READ | REQ_META | REQ_PRIO, 1, &bh);
 793        wait_on_buffer(bh);
 794        if (buffer_uptodate(bh))
 795                return bh;
 796        put_bh(bh);
 797        *err = -EIO;
 798        return NULL;
 799}
 800
 801static int walk_page_buffers(handle_t *handle,
 802                             struct buffer_head *head,
 803                             unsigned from,
 804                             unsigned to,
 805                             int *partial,
 806                             int (*fn)(handle_t *handle,
 807                                       struct buffer_head *bh))
 808{
 809        struct buffer_head *bh;
 810        unsigned block_start, block_end;
 811        unsigned blocksize = head->b_size;
 812        int err, ret = 0;
 813        struct buffer_head *next;
 814
 815        for (bh = head, block_start = 0;
 816             ret == 0 && (bh != head || !block_start);
 817             block_start = block_end, bh = next) {
 818                next = bh->b_this_page;
 819                block_end = block_start + blocksize;
 820                if (block_end <= from || block_start >= to) {
 821                        if (partial && !buffer_uptodate(bh))
 822                                *partial = 1;
 823                        continue;
 824                }
 825                err = (*fn)(handle, bh);
 826                if (!ret)
 827                        ret = err;
 828        }
 829        return ret;
 830}
 831
 832/*
 833 * To preserve ordering, it is essential that the hole instantiation and
 834 * the data write be encapsulated in a single transaction.  We cannot
 835 * close off a transaction and start a new one between the ext4_get_block()
 836 * and the commit_write().  So doing the jbd2_journal_start at the start of
 837 * prepare_write() is the right place.
 838 *
 839 * Also, this function can nest inside ext4_writepage() ->
 840 * block_write_full_page(). In that case, we *know* that ext4_writepage()
 841 * has generated enough buffer credits to do the whole page.  So we won't
 842 * block on the journal in that case, which is good, because the caller may
 843 * be PF_MEMALLOC.
 844 *
 845 * By accident, ext4 can be reentered when a transaction is open via
 846 * quota file writes.  If we were to commit the transaction while thus
 847 * reentered, there can be a deadlock - we would be holding a quota
 848 * lock, and the commit would never complete if another thread had a
 849 * transaction open and was blocking on the quota lock - a ranking
 850 * violation.
 851 *
 852 * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
 853 * will _not_ run commit under these circumstances because handle->h_ref
 854 * is elevated.  We'll still have enough credits for the tiny quotafile
 855 * write.
 856 */
 857static int do_journal_get_write_access(handle_t *handle,
 858                                       struct buffer_head *bh)
 859{
 860        int dirty = buffer_dirty(bh);
 861        int ret;
 862
 863        if (!buffer_mapped(bh) || buffer_freed(bh))
 864                return 0;
 865        /*
 866         * __block_write_begin() could have dirtied some buffers. Clean
 867         * the dirty bit as jbd2_journal_get_write_access() could complain
 868         * otherwise about fs integrity issues. Setting of the dirty bit
 869         * by __block_write_begin() isn't a real problem here as we clear
 870         * the bit before releasing a page lock and thus writeback cannot
 871         * ever write the buffer.
 872         */
 873        if (dirty)
 874                clear_buffer_dirty(bh);
 875        ret = ext4_journal_get_write_access(handle, bh);
 876        if (!ret && dirty)
 877                ret = ext4_handle_dirty_metadata(handle, NULL, bh);
 878        return ret;
 879}
 880
 881static int ext4_get_block_write(struct inode *inode, sector_t iblock,
 882                   struct buffer_head *bh_result, int create);
 883static int ext4_write_begin(struct file *file, struct address_space *mapping,
 884                            loff_t pos, unsigned len, unsigned flags,
 885                            struct page **pagep, void **fsdata)
 886{
 887        struct inode *inode = mapping->host;
 888        int ret, needed_blocks;
 889        handle_t *handle;
 890        int retries = 0;
 891        struct page *page;
 892        pgoff_t index;
 893        unsigned from, to;
 894
 895        trace_ext4_write_begin(inode, pos, len, flags);
 896        /*
 897         * Reserve one block more for addition to orphan list in case
 898         * we allocate blocks but write fails for some reason
 899         */
 900        needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
 901        index = pos >> PAGE_CACHE_SHIFT;
 902        from = pos & (PAGE_CACHE_SIZE - 1);
 903        to = from + len;
 904
 905retry:
 906        handle = ext4_journal_start(inode, needed_blocks);
 907        if (IS_ERR(handle)) {
 908                ret = PTR_ERR(handle);
 909                goto out;
 910        }
 911
 912        /* We cannot recurse into the filesystem as the transaction is already
 913         * started */
 914        flags |= AOP_FLAG_NOFS;
 915
 916        page = grab_cache_page_write_begin(mapping, index, flags);
 917        if (!page) {
 918                ext4_journal_stop(handle);
 919                ret = -ENOMEM;
 920                goto out;
 921        }
 922        *pagep = page;
 923
 924        if (ext4_should_dioread_nolock(inode))
 925                ret = __block_write_begin(page, pos, len, ext4_get_block_write);
 926        else
 927                ret = __block_write_begin(page, pos, len, ext4_get_block);
 928
 929        if (!ret && ext4_should_journal_data(inode)) {
 930                ret = walk_page_buffers(handle, page_buffers(page),
 931                                from, to, NULL, do_journal_get_write_access);
 932        }
 933
 934        if (ret) {
 935                unlock_page(page);
 936                page_cache_release(page);
 937                /*
 938                 * __block_write_begin may have instantiated a few blocks
 939                 * outside i_size.  Trim these off again. Don't need
 940                 * i_size_read because we hold i_mutex.
 941                 *
 942                 * Add inode to orphan list in case we crash before
 943                 * truncate finishes
 944                 */
 945                if (pos + len > inode->i_size && ext4_can_truncate(inode))
 946                        ext4_orphan_add(handle, inode);
 947
 948                ext4_journal_stop(handle);
 949                if (pos + len > inode->i_size) {
 950                        ext4_truncate_failed_write(inode);
 951                        /*
 952                         * If truncate failed early the inode might
 953                         * still be on the orphan list; we need to
 954                         * make sure the inode is removed from the
 955                         * orphan list in that case.
 956                         */
 957                        if (inode->i_nlink)
 958                                ext4_orphan_del(NULL, inode);
 959                }
 960        }
 961
 962        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 963                goto retry;
 964out:
 965        return ret;
 966}
 967
 968/* For write_end() in data=journal mode */
 969static int write_end_fn(handle_t *handle, struct buffer_head *bh)
 970{
 971        if (!buffer_mapped(bh) || buffer_freed(bh))
 972                return 0;
 973        set_buffer_uptodate(bh);
 974        return ext4_handle_dirty_metadata(handle, NULL, bh);
 975}
 976
 977static int ext4_generic_write_end(struct file *file,
 978                                  struct address_space *mapping,
 979                                  loff_t pos, unsigned len, unsigned copied,
 980                                  struct page *page, void *fsdata)
 981{
 982        int i_size_changed = 0;
 983        struct inode *inode = mapping->host;
 984        handle_t *handle = ext4_journal_current_handle();
 985
 986        copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
 987
 988        /*
 989         * No need to use i_size_read() here, the i_size
 990         * cannot change under us because we hold i_mutex.
 991         *
 992         * But it's important to update i_size while still holding page lock:
 993         * page writeout could otherwise come in and zero beyond i_size.
 994         */
 995        if (pos + copied > inode->i_size) {
 996                i_size_write(inode, pos + copied);
 997                i_size_changed = 1;
 998        }
 999
1000        if (pos + copied >  EXT4_I(inode)->i_disksize) {
1001                /* We need to mark inode dirty even if
1002                 * new_i_size is less that inode->i_size
1003                 * bu greater than i_disksize.(hint delalloc)
1004                 */
1005                ext4_update_i_disksize(inode, (pos + copied));
1006                i_size_changed = 1;
1007        }
1008        unlock_page(page);
1009        page_cache_release(page);
1010
1011        /*
1012         * Don't mark the inode dirty under page lock. First, it unnecessarily
1013         * makes the holding time of page lock longer. Second, it forces lock
1014         * ordering of page lock and transaction start for journaling
1015         * filesystems.
1016         */
1017        if (i_size_changed)
1018                ext4_mark_inode_dirty(handle, inode);
1019
1020        return copied;
1021}
1022
1023/*
1024 * We need to pick up the new inode size which generic_commit_write gave us
1025 * `file' can be NULL - eg, when called from page_symlink().
1026 *
1027 * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1028 * buffers are managed internally.
1029 */
1030static int ext4_ordered_write_end(struct file *file,
1031                                  struct address_space *mapping,
1032                                  loff_t pos, unsigned len, unsigned copied,
1033                                  struct page *page, void *fsdata)
1034{
1035        handle_t *handle = ext4_journal_current_handle();
1036        struct inode *inode = mapping->host;
1037        int ret = 0, ret2;
1038
1039        trace_ext4_ordered_write_end(inode, pos, len, copied);
1040        ret = ext4_jbd2_file_inode(handle, inode);
1041
1042        if (ret == 0) {
1043                ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1044                                                        page, fsdata);
1045                copied = ret2;
1046                if (pos + len > inode->i_size && ext4_can_truncate(inode))
1047                        /* if we have allocated more blocks and copied
1048                         * less. We will have blocks allocated outside
1049                         * inode->i_size. So truncate them
1050                         */
1051                        ext4_orphan_add(handle, inode);
1052                if (ret2 < 0)
1053                        ret = ret2;
1054        } else {
1055                unlock_page(page);
1056                page_cache_release(page);
1057        }
1058
1059        ret2 = ext4_journal_stop(handle);
1060        if (!ret)
1061                ret = ret2;
1062
1063        if (pos + len > inode->i_size) {
1064                ext4_truncate_failed_write(inode);
1065                /*
1066                 * If truncate failed early the inode might still be
1067                 * on the orphan list; we need to make sure the inode
1068                 * is removed from the orphan list in that case.
1069                 */
1070                if (inode->i_nlink)
1071                        ext4_orphan_del(NULL, inode);
1072        }
1073
1074
1075        return ret ? ret : copied;
1076}
1077
1078static int ext4_writeback_write_end(struct file *file,
1079                                    struct address_space *mapping,
1080                                    loff_t pos, unsigned len, unsigned copied,
1081                                    struct page *page, void *fsdata)
1082{
1083        handle_t *handle = ext4_journal_current_handle();
1084        struct inode *inode = mapping->host;
1085        int ret = 0, ret2;
1086
1087        trace_ext4_writeback_write_end(inode, pos, len, copied);
1088        ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1089                                                        page, fsdata);
1090        copied = ret2;
1091        if (pos + len > inode->i_size && ext4_can_truncate(inode))
1092                /* if we have allocated more blocks and copied
1093                 * less. We will have blocks allocated outside
1094                 * inode->i_size. So truncate them
1095                 */
1096                ext4_orphan_add(handle, inode);
1097
1098        if (ret2 < 0)
1099                ret = ret2;
1100
1101        ret2 = ext4_journal_stop(handle);
1102        if (!ret)
1103                ret = ret2;
1104
1105        if (pos + len > inode->i_size) {
1106                ext4_truncate_failed_write(inode);
1107                /*
1108                 * If truncate failed early the inode might still be
1109                 * on the orphan list; we need to make sure the inode
1110                 * is removed from the orphan list in that case.
1111                 */
1112                if (inode->i_nlink)
1113                        ext4_orphan_del(NULL, inode);
1114        }
1115
1116        return ret ? ret : copied;
1117}
1118
1119static int ext4_journalled_write_end(struct file *file,
1120                                     struct address_space *mapping,
1121                                     loff_t pos, unsigned len, unsigned copied,
1122                                     struct page *page, void *fsdata)
1123{
1124        handle_t *handle = ext4_journal_current_handle();
1125        struct inode *inode = mapping->host;
1126        int ret = 0, ret2;
1127        int partial = 0;
1128        unsigned from, to;
1129        loff_t new_i_size;
1130
1131        trace_ext4_journalled_write_end(inode, pos, len, copied);
1132        from = pos & (PAGE_CACHE_SIZE - 1);
1133        to = from + len;
1134
1135        BUG_ON(!ext4_handle_valid(handle));
1136
1137        if (copied < len) {
1138                if (!PageUptodate(page))
1139                        copied = 0;
1140                page_zero_new_buffers(page, from+copied, to);
1141        }
1142
1143        ret = walk_page_buffers(handle, page_buffers(page), from,
1144                                to, &partial, write_end_fn);
1145        if (!partial)
1146                SetPageUptodate(page);
1147        new_i_size = pos + copied;
1148        if (new_i_size > inode->i_size)
1149                i_size_write(inode, pos+copied);
1150        ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1151        EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1152        if (new_i_size > EXT4_I(inode)->i_disksize) {
1153                ext4_update_i_disksize(inode, new_i_size);
1154                ret2 = ext4_mark_inode_dirty(handle, inode);
1155                if (!ret)
1156                        ret = ret2;
1157        }
1158
1159        unlock_page(page);
1160        page_cache_release(page);
1161        if (pos + len > inode->i_size && ext4_can_truncate(inode))
1162                /* if we have allocated more blocks and copied
1163                 * less. We will have blocks allocated outside
1164                 * inode->i_size. So truncate them
1165                 */
1166                ext4_orphan_add(handle, inode);
1167
1168        ret2 = ext4_journal_stop(handle);
1169        if (!ret)
1170                ret = ret2;
1171        if (pos + len > inode->i_size) {
1172                ext4_truncate_failed_write(inode);
1173                /*
1174                 * If truncate failed early the inode might still be
1175                 * on the orphan list; we need to make sure the inode
1176                 * is removed from the orphan list in that case.
1177                 */
1178                if (inode->i_nlink)
1179                        ext4_orphan_del(NULL, inode);
1180        }
1181
1182        return ret ? ret : copied;
1183}
1184
1185/*
1186 * Reserve a single cluster located at lblock
1187 */
1188static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
1189{
1190        int retries = 0;
1191        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1192        struct ext4_inode_info *ei = EXT4_I(inode);
1193        unsigned int md_needed;
1194        int ret;
1195        ext4_lblk_t save_last_lblock;
1196        int save_len;
1197
1198        /*
1199         * We will charge metadata quota at writeout time; this saves
1200         * us from metadata over-estimation, though we may go over by
1201         * a small amount in the end.  Here we just reserve for data.
1202         */
1203        ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
1204        if (ret)
1205                return ret;
1206
1207        /*
1208         * recalculate the amount of metadata blocks to reserve
1209         * in order to allocate nrblocks
1210         * worse case is one extent per block
1211         */
1212repeat:
1213        spin_lock(&ei->i_block_reservation_lock);
1214        /*
1215         * ext4_calc_metadata_amount() has side effects, which we have
1216         * to be prepared undo if we fail to claim space.
1217         */
1218        save_len = ei->i_da_metadata_calc_len;
1219        save_last_lblock = ei->i_da_metadata_calc_last_lblock;
1220        md_needed = EXT4_NUM_B2C(sbi,
1221                                 ext4_calc_metadata_amount(inode, lblock));
1222        trace_ext4_da_reserve_space(inode, md_needed);
1223
1224        /*
1225         * We do still charge estimated metadata to the sb though;
1226         * we cannot afford to run out of free blocks.
1227         */
1228        if (ext4_claim_free_clusters(sbi, md_needed + 1, 0)) {
1229                ei->i_da_metadata_calc_len = save_len;
1230                ei->i_da_metadata_calc_last_lblock = save_last_lblock;
1231                spin_unlock(&ei->i_block_reservation_lock);
1232                if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1233                        yield();
1234                        goto repeat;
1235                }
1236                dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
1237                return -ENOSPC;
1238        }
1239        ei->i_reserved_data_blocks++;
1240        ei->i_reserved_meta_blocks += md_needed;
1241        spin_unlock(&ei->i_block_reservation_lock);
1242
1243        return 0;       /* success */
1244}
1245
1246static void ext4_da_release_space(struct inode *inode, int to_free)
1247{
1248        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1249        struct ext4_inode_info *ei = EXT4_I(inode);
1250
1251        if (!to_free)
1252                return;         /* Nothing to release, exit */
1253
1254        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1255
1256        trace_ext4_da_release_space(inode, to_free);
1257        if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1258                /*
1259                 * if there aren't enough reserved blocks, then the
1260                 * counter is messed up somewhere.  Since this
1261                 * function is called from invalidate page, it's
1262                 * harmless to return without any action.
1263                 */
1264                ext4_msg(inode->i_sb, KERN_NOTICE, "ext4_da_release_space: "
1265                         "ino %lu, to_free %d with only %d reserved "
1266                         "data blocks", inode->i_ino, to_free,
1267                         ei->i_reserved_data_blocks);
1268                WARN_ON(1);
1269                to_free = ei->i_reserved_data_blocks;
1270        }
1271        ei->i_reserved_data_blocks -= to_free;
1272
1273        if (ei->i_reserved_data_blocks == 0) {
1274                /*
1275                 * We can release all of the reserved metadata blocks
1276                 * only when we have written all of the delayed
1277                 * allocation blocks.
1278                 * Note that in case of bigalloc, i_reserved_meta_blocks,
1279                 * i_reserved_data_blocks, etc. refer to number of clusters.
1280                 */
1281                percpu_counter_sub(&sbi->s_dirtyclusters_counter,
1282                                   ei->i_reserved_meta_blocks);
1283                ei->i_reserved_meta_blocks = 0;
1284                ei->i_da_metadata_calc_len = 0;
1285        }
1286
1287        /* update fs dirty data blocks counter */
1288        percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
1289
1290        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1291
1292        dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
1293}
1294
1295static void ext4_da_page_release_reservation(struct page *page,
1296                                             unsigned long offset)
1297{
1298        int to_release = 0;
1299        struct buffer_head *head, *bh;
1300        unsigned int curr_off = 0;
1301        struct inode *inode = page->mapping->host;
1302        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1303        int num_clusters;
1304
1305        head = page_buffers(page);
1306        bh = head;
1307        do {
1308                unsigned int next_off = curr_off + bh->b_size;
1309
1310                if ((offset <= curr_off) && (buffer_delay(bh))) {
1311                        to_release++;
1312                        clear_buffer_delay(bh);
1313                        clear_buffer_da_mapped(bh);
1314                }
1315                curr_off = next_off;
1316        } while ((bh = bh->b_this_page) != head);
1317
1318        /* If we have released all the blocks belonging to a cluster, then we
1319         * need to release the reserved space for that cluster. */
1320        num_clusters = EXT4_NUM_B2C(sbi, to_release);
1321        while (num_clusters > 0) {
1322                ext4_fsblk_t lblk;
1323                lblk = (page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits)) +
1324                        ((num_clusters - 1) << sbi->s_cluster_bits);
1325                if (sbi->s_cluster_ratio == 1 ||
1326                    !ext4_find_delalloc_cluster(inode, lblk, 1))
1327                        ext4_da_release_space(inode, 1);
1328
1329                num_clusters--;
1330        }
1331}
1332
1333/*
1334 * Delayed allocation stuff
1335 */
1336
1337/*
1338 * mpage_da_submit_io - walks through extent of pages and try to write
1339 * them with writepage() call back
1340 *
1341 * @mpd->inode: inode
1342 * @mpd->first_page: first page of the extent
1343 * @mpd->next_page: page after the last page of the extent
1344 *
1345 * By the time mpage_da_submit_io() is called we expect all blocks
1346 * to be allocated. this may be wrong if allocation failed.
1347 *
1348 * As pages are already locked by write_cache_pages(), we can't use it
1349 */
1350static int mpage_da_submit_io(struct mpage_da_data *mpd,
1351                              struct ext4_map_blocks *map)
1352{
1353        struct pagevec pvec;
1354        unsigned long index, end;
1355        int ret = 0, err, nr_pages, i;
1356        struct inode *inode = mpd->inode;
1357        struct address_space *mapping = inode->i_mapping;
1358        loff_t size = i_size_read(inode);
1359        unsigned int len, block_start;
1360        struct buffer_head *bh, *page_bufs = NULL;
1361        int journal_data = ext4_should_journal_data(inode);
1362        sector_t pblock = 0, cur_logical = 0;
1363        struct ext4_io_submit io_submit;
1364
1365        BUG_ON(mpd->next_page <= mpd->first_page);
1366        memset(&io_submit, 0, sizeof(io_submit));
1367        /*
1368         * We need to start from the first_page to the next_page - 1
1369         * to make sure we also write the mapped dirty buffer_heads.
1370         * If we look at mpd->b_blocknr we would only be looking
1371         * at the currently mapped buffer_heads.
1372         */
1373        index = mpd->first_page;
1374        end = mpd->next_page - 1;
1375
1376        pagevec_init(&pvec, 0);
1377        while (index <= end) {
1378                nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1379                if (nr_pages == 0)
1380                        break;
1381                for (i = 0; i < nr_pages; i++) {
1382                        int commit_write = 0, skip_page = 0;
1383                        struct page *page = pvec.pages[i];
1384
1385                        index = page->index;
1386                        if (index > end)
1387                                break;
1388
1389                        if (index == size >> PAGE_CACHE_SHIFT)
1390                                len = size & ~PAGE_CACHE_MASK;
1391                        else
1392                                len = PAGE_CACHE_SIZE;
1393                        if (map) {
1394                                cur_logical = index << (PAGE_CACHE_SHIFT -
1395                                                        inode->i_blkbits);
1396                                pblock = map->m_pblk + (cur_logical -
1397                                                        map->m_lblk);
1398                        }
1399                        index++;
1400
1401                        BUG_ON(!PageLocked(page));
1402                        BUG_ON(PageWriteback(page));
1403
1404                        /*
1405                         * If the page does not have buffers (for
1406                         * whatever reason), try to create them using
1407                         * __block_write_begin.  If this fails,
1408                         * skip the page and move on.
1409                         */
1410                        if (!page_has_buffers(page)) {
1411                                if (__block_write_begin(page, 0, len,
1412                                                noalloc_get_block_write)) {
1413                                skip_page:
1414                                        unlock_page(page);
1415                                        continue;
1416                                }
1417                                commit_write = 1;
1418                        }
1419
1420                        bh = page_bufs = page_buffers(page);
1421                        block_start = 0;
1422                        do {
1423                                if (!bh)
1424                                        goto skip_page;
1425                                if (map && (cur_logical >= map->m_lblk) &&
1426                                    (cur_logical <= (map->m_lblk +
1427                                                     (map->m_len - 1)))) {
1428                                        if (buffer_delay(bh)) {
1429                                                clear_buffer_delay(bh);
1430                                                bh->b_blocknr = pblock;
1431                                        }
1432                                        if (buffer_da_mapped(bh))
1433                                                clear_buffer_da_mapped(bh);
1434                                        if (buffer_unwritten(bh) ||
1435                                            buffer_mapped(bh))
1436                                                BUG_ON(bh->b_blocknr != pblock);
1437                                        if (map->m_flags & EXT4_MAP_UNINIT)
1438                                                set_buffer_uninit(bh);
1439                                        clear_buffer_unwritten(bh);
1440                                }
1441
1442                                /*
1443                                 * skip page if block allocation undone and
1444                                 * block is dirty
1445                                 */
1446                                if (ext4_bh_delay_or_unwritten(NULL, bh))
1447                                        skip_page = 1;
1448                                bh = bh->b_this_page;
1449                                block_start += bh->b_size;
1450                                cur_logical++;
1451                                pblock++;
1452                        } while (bh != page_bufs);
1453
1454                        if (skip_page)
1455                                goto skip_page;
1456
1457                        if (commit_write)
1458                                /* mark the buffer_heads as dirty & uptodate */
1459                                block_commit_write(page, 0, len);
1460
1461                        clear_page_dirty_for_io(page);
1462                        /*
1463                         * Delalloc doesn't support data journalling,
1464                         * but eventually maybe we'll lift this
1465                         * restriction.
1466                         */
1467                        if (unlikely(journal_data && PageChecked(page)))
1468                                err = __ext4_journalled_writepage(page, len);
1469                        else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT))
1470                                err = ext4_bio_write_page(&io_submit, page,
1471                                                          len, mpd->wbc);
1472                        else if (buffer_uninit(page_bufs)) {
1473                                ext4_set_bh_endio(page_bufs, inode);
1474                                err = block_write_full_page_endio(page,
1475                                        noalloc_get_block_write,
1476                                        mpd->wbc, ext4_end_io_buffer_write);
1477                        } else
1478                                err = block_write_full_page(page,
1479                                        noalloc_get_block_write, mpd->wbc);
1480
1481                        if (!err)
1482                                mpd->pages_written++;
1483                        /*
1484                         * In error case, we have to continue because
1485                         * remaining pages are still locked
1486                         */
1487                        if (ret == 0)
1488                                ret = err;
1489                }
1490                pagevec_release(&pvec);
1491        }
1492        ext4_io_submit(&io_submit);
1493        return ret;
1494}
1495
1496static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd)
1497{
1498        int nr_pages, i;
1499        pgoff_t index, end;
1500        struct pagevec pvec;
1501        struct inode *inode = mpd->inode;
1502        struct address_space *mapping = inode->i_mapping;
1503
1504        index = mpd->first_page;
1505        end   = mpd->next_page - 1;
1506
1507        pagevec_init(&pvec, 0);
1508        while (index <= end) {
1509                nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1510                if (nr_pages == 0)
1511                        break;
1512                for (i = 0; i < nr_pages; i++) {
1513                        struct page *page = pvec.pages[i];
1514                        if (page->index > end)
1515                                break;
1516                        BUG_ON(!PageLocked(page));
1517                        BUG_ON(PageWriteback(page));
1518                        block_invalidatepage(page, 0);
1519                        ClearPageUptodate(page);
1520                        unlock_page(page);
1521                }
1522                index = pvec.pages[nr_pages - 1]->index + 1;
1523                pagevec_release(&pvec);
1524        }
1525        return;
1526}
1527
1528static void ext4_print_free_blocks(struct inode *inode)
1529{
1530        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1531        struct super_block *sb = inode->i_sb;
1532
1533        ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
1534               EXT4_C2B(EXT4_SB(inode->i_sb),
1535                        ext4_count_free_clusters(inode->i_sb)));
1536        ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
1537        ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
1538               (long long) EXT4_C2B(EXT4_SB(inode->i_sb),
1539                percpu_counter_sum(&sbi->s_freeclusters_counter)));
1540        ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
1541               (long long) EXT4_C2B(EXT4_SB(inode->i_sb),
1542                percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
1543        ext4_msg(sb, KERN_CRIT, "Block reservation details");
1544        ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
1545                 EXT4_I(inode)->i_reserved_data_blocks);
1546        ext4_msg(sb, KERN_CRIT, "i_reserved_meta_blocks=%u",
1547               EXT4_I(inode)->i_reserved_meta_blocks);
1548        return;
1549}
1550
1551/*
1552 * mpage_da_map_and_submit - go through given space, map them
1553 *       if necessary, and then submit them for I/O
1554 *
1555 * @mpd - bh describing space
1556 *
1557 * The function skips space we know is already mapped to disk blocks.
1558 *
1559 */
1560static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
1561{
1562        int err, blks, get_blocks_flags;
1563        struct ext4_map_blocks map, *mapp = NULL;
1564        sector_t next = mpd->b_blocknr;
1565        unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
1566        loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
1567        handle_t *handle = NULL;
1568
1569        /*
1570         * If the blocks are mapped already, or we couldn't accumulate
1571         * any blocks, then proceed immediately to the submission stage.
1572         */
1573        if ((mpd->b_size == 0) ||
1574            ((mpd->b_state  & (1 << BH_Mapped)) &&
1575             !(mpd->b_state & (1 << BH_Delay)) &&
1576             !(mpd->b_state & (1 << BH_Unwritten))))
1577                goto submit_io;
1578
1579        handle = ext4_journal_current_handle();
1580        BUG_ON(!handle);
1581
1582        /*
1583         * Call ext4_map_blocks() to allocate any delayed allocation
1584         * blocks, or to convert an uninitialized extent to be
1585         * initialized (in the case where we have written into
1586         * one or more preallocated blocks).
1587         *
1588         * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
1589         * indicate that we are on the delayed allocation path.  This
1590         * affects functions in many different parts of the allocation
1591         * call path.  This flag exists primarily because we don't
1592         * want to change *many* call functions, so ext4_map_blocks()
1593         * will set the EXT4_STATE_DELALLOC_RESERVED flag once the
1594         * inode's allocation semaphore is taken.
1595         *
1596         * If the blocks in questions were delalloc blocks, set
1597         * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
1598         * variables are updated after the blocks have been allocated.
1599         */
1600        map.m_lblk = next;
1601        map.m_len = max_blocks;
1602        get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
1603        if (ext4_should_dioread_nolock(mpd->inode))
1604                get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
1605        if (mpd->b_state & (1 << BH_Delay))
1606                get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
1607
1608        blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
1609        if (blks < 0) {
1610                struct super_block *sb = mpd->inode->i_sb;
1611
1612                err = blks;
1613                /*
1614                 * If get block returns EAGAIN or ENOSPC and there
1615                 * appears to be free blocks we will just let
1616                 * mpage_da_submit_io() unlock all of the pages.
1617                 */
1618                if (err == -EAGAIN)
1619                        goto submit_io;
1620
1621                if (err == -ENOSPC && ext4_count_free_clusters(sb)) {
1622                        mpd->retval = err;
1623                        goto submit_io;
1624                }
1625
1626                /*
1627                 * get block failure will cause us to loop in
1628                 * writepages, because a_ops->writepage won't be able
1629                 * to make progress. The page will be redirtied by
1630                 * writepage and writepages will again try to write
1631                 * the same.
1632                 */
1633                if (!(EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)) {
1634                        ext4_msg(sb, KERN_CRIT,
1635                                 "delayed block allocation failed for inode %lu "
1636                                 "at logical offset %llu with max blocks %zd "
1637                                 "with error %d", mpd->inode->i_ino,
1638                                 (unsigned long long) next,
1639                                 mpd->b_size >> mpd->inode->i_blkbits, err);
1640                        ext4_msg(sb, KERN_CRIT,
1641                                "This should not happen!! Data will be lost\n");
1642                        if (err == -ENOSPC)
1643                                ext4_print_free_blocks(mpd->inode);
1644                }
1645                /* invalidate all the pages */
1646                ext4_da_block_invalidatepages(mpd);
1647
1648                /* Mark this page range as having been completed */
1649                mpd->io_done = 1;
1650                return;
1651        }
1652        BUG_ON(blks == 0);
1653
1654        mapp = &map;
1655        if (map.m_flags & EXT4_MAP_NEW) {
1656                struct block_device *bdev = mpd->inode->i_sb->s_bdev;
1657                int i;
1658
1659                for (i = 0; i < map.m_len; i++)
1660                        unmap_underlying_metadata(bdev, map.m_pblk + i);
1661
1662                if (ext4_should_order_data(mpd->inode)) {
1663                        err = ext4_jbd2_file_inode(handle, mpd->inode);
1664                        if (err) {
1665                                /* Only if the journal is aborted */
1666                                mpd->retval = err;
1667                                goto submit_io;
1668                        }
1669                }
1670        }
1671
1672        /*
1673         * Update on-disk size along with block allocation.
1674         */
1675        disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
1676        if (disksize > i_size_read(mpd->inode))
1677                disksize = i_size_read(mpd->inode);
1678        if (disksize > EXT4_I(mpd->inode)->i_disksize) {
1679                ext4_update_i_disksize(mpd->inode, disksize);
1680                err = ext4_mark_inode_dirty(handle, mpd->inode);
1681                if (err)
1682                        ext4_error(mpd->inode->i_sb,
1683                                   "Failed to mark inode %lu dirty",
1684                                   mpd->inode->i_ino);
1685        }
1686
1687submit_io:
1688        mpage_da_submit_io(mpd, mapp);
1689        mpd->io_done = 1;
1690}
1691
1692#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
1693                (1 << BH_Delay) | (1 << BH_Unwritten))
1694
1695/*
1696 * mpage_add_bh_to_extent - try to add one more block to extent of blocks
1697 *
1698 * @mpd->lbh - extent of blocks
1699 * @logical - logical number of the block in the file
1700 * @bh - bh of the block (used to access block's state)
1701 *
1702 * the function is used to collect contig. blocks in same state
1703 */
1704static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
1705                                   sector_t logical, size_t b_size,
1706                                   unsigned long b_state)
1707{
1708        sector_t next;
1709        int nrblocks = mpd->b_size >> mpd->inode->i_blkbits;
1710
1711        /*
1712         * XXX Don't go larger than mballoc is willing to allocate
1713         * This is a stopgap solution.  We eventually need to fold
1714         * mpage_da_submit_io() into this function and then call
1715         * ext4_map_blocks() multiple times in a loop
1716         */
1717        if (nrblocks >= 8*1024*1024/mpd->inode->i_sb->s_blocksize)
1718                goto flush_it;
1719
1720        /* check if thereserved journal credits might overflow */
1721        if (!(ext4_test_inode_flag(mpd->inode, EXT4_INODE_EXTENTS))) {
1722                if (nrblocks >= EXT4_MAX_TRANS_DATA) {
1723                        /*
1724                         * With non-extent format we are limited by the journal
1725                         * credit available.  Total credit needed to insert
1726                         * nrblocks contiguous blocks is dependent on the
1727                         * nrblocks.  So limit nrblocks.
1728                         */
1729                        goto flush_it;
1730                } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
1731                                EXT4_MAX_TRANS_DATA) {
1732                        /*
1733                         * Adding the new buffer_head would make it cross the
1734                         * allowed limit for which we have journal credit
1735                         * reserved. So limit the new bh->b_size
1736                         */
1737                        b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
1738                                                mpd->inode->i_blkbits;
1739                        /* we will do mpage_da_submit_io in the next loop */
1740                }
1741        }
1742        /*
1743         * First block in the extent
1744         */
1745        if (mpd->b_size == 0) {
1746                mpd->b_blocknr = logical;
1747                mpd->b_size = b_size;
1748                mpd->b_state = b_state & BH_FLAGS;
1749                return;
1750        }
1751
1752        next = mpd->b_blocknr + nrblocks;
1753        /*
1754         * Can we merge the block to our big extent?
1755         */
1756        if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
1757                mpd->b_size += b_size;
1758                return;
1759        }
1760
1761flush_it:
1762        /*
1763         * We couldn't merge the block to our extent, so we
1764         * need to flush current  extent and start new one
1765         */
1766        mpage_da_map_and_submit(mpd);
1767        return;
1768}
1769
1770static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1771{
1772        return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1773}
1774
1775/*
1776 * This function is grabs code from the very beginning of
1777 * ext4_map_blocks, but assumes that the caller is from delayed write
1778 * time. This function looks up the requested blocks and sets the
1779 * buffer delay bit under the protection of i_data_sem.
1780 */
1781static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
1782                              struct ext4_map_blocks *map,
1783                              struct buffer_head *bh)
1784{
1785        int retval;
1786        sector_t invalid_block = ~((sector_t) 0xffff);
1787
1788        if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1789                invalid_block = ~0;
1790
1791        map->m_flags = 0;
1792        ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
1793                  "logical block %lu\n", inode->i_ino, map->m_len,
1794                  (unsigned long) map->m_lblk);
1795        /*
1796         * Try to see if we can get the block without requesting a new
1797         * file system block.
1798         */
1799        down_read((&EXT4_I(inode)->i_data_sem));
1800        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1801                retval = ext4_ext_map_blocks(NULL, inode, map, 0);
1802        else
1803                retval = ext4_ind_map_blocks(NULL, inode, map, 0);
1804
1805        if (retval == 0) {
1806                /*
1807                 * XXX: __block_prepare_write() unmaps passed block,
1808                 * is it OK?
1809                 */
1810                /* If the block was allocated from previously allocated cluster,
1811                 * then we dont need to reserve it again. */
1812                if (!(map->m_flags & EXT4_MAP_FROM_CLUSTER)) {
1813                        retval = ext4_da_reserve_space(inode, iblock);
1814                        if (retval)
1815                                /* not enough space to reserve */
1816                                goto out_unlock;
1817                }
1818
1819                /* Clear EXT4_MAP_FROM_CLUSTER flag since its purpose is served
1820                 * and it should not appear on the bh->b_state.
1821                 */
1822                map->m_flags &= ~EXT4_MAP_FROM_CLUSTER;
1823
1824                map_bh(bh, inode->i_sb, invalid_block);
1825                set_buffer_new(bh);
1826                set_buffer_delay(bh);
1827        }
1828
1829out_unlock:
1830        up_read((&EXT4_I(inode)->i_data_sem));
1831
1832        return retval;
1833}
1834
1835/*
1836 * This is a special get_blocks_t callback which is used by
1837 * ext4_da_write_begin().  It will either return mapped block or
1838 * reserve space for a single block.
1839 *
1840 * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1841 * We also have b_blocknr = -1 and b_bdev initialized properly
1842 *
1843 * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1844 * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1845 * initialized properly.
1846 */
1847static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1848                                  struct buffer_head *bh, int create)
1849{
1850        struct ext4_map_blocks map;
1851        int ret = 0;
1852
1853        BUG_ON(create == 0);
1854        BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1855
1856        map.m_lblk = iblock;
1857        map.m_len = 1;
1858
1859        /*
1860         * first, we need to know whether the block is allocated already
1861         * preallocated blocks are unmapped but should treated
1862         * the same as allocated blocks.
1863         */
1864        ret = ext4_da_map_blocks(inode, iblock, &map, bh);
1865        if (ret <= 0)
1866                return ret;
1867
1868        map_bh(bh, inode->i_sb, map.m_pblk);
1869        bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
1870
1871        if (buffer_unwritten(bh)) {
1872                /* A delayed write to unwritten bh should be marked
1873                 * new and mapped.  Mapped ensures that we don't do
1874                 * get_block multiple times when we write to the same
1875                 * offset and new ensures that we do proper zero out
1876                 * for partial write.
1877                 */
1878                set_buffer_new(bh);
1879                set_buffer_mapped(bh);
1880        }
1881        return 0;
1882}
1883
1884/*
1885 * This function is used as a standard get_block_t calback function
1886 * when there is no desire to allocate any blocks.  It is used as a
1887 * callback function for block_write_begin() and block_write_full_page().
1888 * These functions should only try to map a single block at a time.
1889 *
1890 * Since this function doesn't do block allocations even if the caller
1891 * requests it by passing in create=1, it is critically important that
1892 * any caller checks to make sure that any buffer heads are returned
1893 * by this function are either all already mapped or marked for
1894 * delayed allocation before calling  block_write_full_page().  Otherwise,
1895 * b_blocknr could be left unitialized, and the page write functions will
1896 * be taken by surprise.
1897 */
1898static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
1899                                   struct buffer_head *bh_result, int create)
1900{
1901        BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
1902        return _ext4_get_block(inode, iblock, bh_result, 0);
1903}
1904
1905static int bget_one(handle_t *handle, struct buffer_head *bh)
1906{
1907        get_bh(bh);
1908        return 0;
1909}
1910
1911static int bput_one(handle_t *handle, struct buffer_head *bh)
1912{
1913        put_bh(bh);
1914        return 0;
1915}
1916
1917static int __ext4_journalled_writepage(struct page *page,
1918                                       unsigned int len)
1919{
1920        struct address_space *mapping = page->mapping;
1921        struct inode *inode = mapping->host;
1922        struct buffer_head *page_bufs;
1923        handle_t *handle = NULL;
1924        int ret = 0;
1925        int err;
1926
1927        ClearPageChecked(page);
1928        page_bufs = page_buffers(page);
1929        BUG_ON(!page_bufs);
1930        walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
1931        /* As soon as we unlock the page, it can go away, but we have
1932         * references to buffers so we are safe */
1933        unlock_page(page);
1934
1935        handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1936        if (IS_ERR(handle)) {
1937                ret = PTR_ERR(handle);
1938                goto out;
1939        }
1940
1941        BUG_ON(!ext4_handle_valid(handle));
1942
1943        ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
1944                                do_journal_get_write_access);
1945
1946        err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
1947                                write_end_fn);
1948        if (ret == 0)
1949                ret = err;
1950        EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1951        err = ext4_journal_stop(handle);
1952        if (!ret)
1953                ret = err;
1954
1955        walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
1956        ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1957out:
1958        return ret;
1959}
1960
1961/*
1962 * Note that we don't need to start a transaction unless we're journaling data
1963 * because we should have holes filled from ext4_page_mkwrite(). We even don't
1964 * need to file the inode to the transaction's list in ordered mode because if
1965 * we are writing back data added by write(), the inode is already there and if
1966 * we are writing back data modified via mmap(), no one guarantees in which
1967 * transaction the data will hit the disk. In case we are journaling data, we
1968 * cannot start transaction directly because transaction start ranks above page
1969 * lock so we have to do some magic.
1970 *
1971 * This function can get called via...
1972 *   - ext4_da_writepages after taking page lock (have journal handle)
1973 *   - journal_submit_inode_data_buffers (no journal handle)
1974 *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
1975 *   - grab_page_cache when doing write_begin (have journal handle)
1976 *
1977 * We don't do any block allocation in this function. If we have page with
1978 * multiple blocks we need to write those buffer_heads that are mapped. This
1979 * is important for mmaped based write. So if we do with blocksize 1K
1980 * truncate(f, 1024);
1981 * a = mmap(f, 0, 4096);
1982 * a[0] = 'a';
1983 * truncate(f, 4096);
1984 * we have in the page first buffer_head mapped via page_mkwrite call back
1985 * but other buffer_heads would be unmapped but dirty (dirty done via the
1986 * do_wp_page). So writepage should write the first block. If we modify
1987 * the mmap area beyond 1024 we will again get a page_fault and the
1988 * page_mkwrite callback will do the block allocation and mark the
1989 * buffer_heads mapped.
1990 *
1991 * We redirty the page if we have any buffer_heads that is either delay or
1992 * unwritten in the page.
1993 *
1994 * We can get recursively called as show below.
1995 *
1996 *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
1997 *              ext4_writepage()
1998 *
1999 * But since we don't do any block allocation we should not deadlock.
2000 * Page also have the dirty flag cleared so we don't get recurive page_lock.
2001 */
2002static int ext4_writepage(struct page *page,
2003                          struct writeback_control *wbc)
2004{
2005        int ret = 0, commit_write = 0;
2006        loff_t size;
2007        unsigned int len;
2008        struct buffer_head *page_bufs = NULL;
2009        struct inode *inode = page->mapping->host;
2010
2011        trace_ext4_writepage(page);
2012        size = i_size_read(inode);
2013        if (page->index == size >> PAGE_CACHE_SHIFT)
2014                len = size & ~PAGE_CACHE_MASK;
2015        else
2016                len = PAGE_CACHE_SIZE;
2017
2018        /*
2019         * If the page does not have buffers (for whatever reason),
2020         * try to create them using __block_write_begin.  If this
2021         * fails, redirty the page and move on.
2022         */
2023        if (!page_has_buffers(page)) {
2024                if (__block_write_begin(page, 0, len,
2025                                        noalloc_get_block_write)) {
2026                redirty_page:
2027                        redirty_page_for_writepage(wbc, page);
2028                        unlock_page(page);
2029                        return 0;
2030                }
2031                commit_write = 1;
2032        }
2033        page_bufs = page_buffers(page);
2034        if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2035                              ext4_bh_delay_or_unwritten)) {
2036                /*
2037                 * We don't want to do block allocation, so redirty
2038                 * the page and return.  We may reach here when we do
2039                 * a journal commit via journal_submit_inode_data_buffers.
2040                 * We can also reach here via shrink_page_list but it
2041                 * should never be for direct reclaim so warn if that
2042                 * happens
2043                 */
2044                WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
2045                                                                PF_MEMALLOC);
2046                goto redirty_page;
2047        }
2048        if (commit_write)
2049                /* now mark the buffer_heads as dirty and uptodate */
2050                block_commit_write(page, 0, len);
2051
2052        if (PageChecked(page) && ext4_should_journal_data(inode))
2053                /*
2054                 * It's mmapped pagecache.  Add buffers and journal it.  There
2055                 * doesn't seem much point in redirtying the page here.
2056                 */
2057                return __ext4_journalled_writepage(page, len);
2058
2059        if (buffer_uninit(page_bufs)) {
2060                ext4_set_bh_endio(page_bufs, inode);
2061                ret = block_write_full_page_endio(page, noalloc_get_block_write,
2062                                            wbc, ext4_end_io_buffer_write);
2063        } else
2064                ret = block_write_full_page(page, noalloc_get_block_write,
2065                                            wbc);
2066
2067        return ret;
2068}
2069
2070/*
2071 * This is called via ext4_da_writepages() to
2072 * calculate the total number of credits to reserve to fit
2073 * a single extent allocation into a single transaction,
2074 * ext4_da_writpeages() will loop calling this before
2075 * the block allocation.
2076 */
2077
2078static int ext4_da_writepages_trans_blocks(struct inode *inode)
2079{
2080        int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
2081
2082        /*
2083         * With non-extent format the journal credit needed to
2084         * insert nrblocks contiguous block is dependent on
2085         * number of contiguous block. So we will limit
2086         * number of contiguous block to a sane value
2087         */
2088        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
2089            (max_blocks > EXT4_MAX_TRANS_DATA))
2090                max_blocks = EXT4_MAX_TRANS_DATA;
2091
2092        return ext4_chunk_trans_blocks(inode, max_blocks);
2093}
2094
2095/*
2096 * write_cache_pages_da - walk the list of dirty pages of the given
2097 * address space and accumulate pages that need writing, and call
2098 * mpage_da_map_and_submit to map a single contiguous memory region
2099 * and then write them.
2100 */
2101static int write_cache_pages_da(struct address_space *mapping,
2102                                struct writeback_control *wbc,
2103                                struct mpage_da_data *mpd,
2104                                pgoff_t *done_index)
2105{
2106        struct buffer_head      *bh, *head;
2107        struct inode            *inode = mapping->host;
2108        struct pagevec          pvec;
2109        unsigned int            nr_pages;
2110        sector_t                logical;
2111        pgoff_t                 index, end;
2112        long                    nr_to_write = wbc->nr_to_write;
2113        int                     i, tag, ret = 0;
2114
2115        memset(mpd, 0, sizeof(struct mpage_da_data));
2116        mpd->wbc = wbc;
2117        mpd->inode = inode;
2118        pagevec_init(&pvec, 0);
2119        index = wbc->range_start >> PAGE_CACHE_SHIFT;
2120        end = wbc->range_end >> PAGE_CACHE_SHIFT;
2121
2122        if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2123                tag = PAGECACHE_TAG_TOWRITE;
2124        else
2125                tag = PAGECACHE_TAG_DIRTY;
2126
2127        *done_index = index;
2128        while (index <= end) {
2129                nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
2130                              min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2131                if (nr_pages == 0)
2132                        return 0;
2133
2134                for (i = 0; i < nr_pages; i++) {
2135                        struct page *page = pvec.pages[i];
2136
2137                        /*
2138                         * At this point, the page may be truncated or
2139                         * invalidated (changing page->mapping to NULL), or
2140                         * even swizzled back from swapper_space to tmpfs file
2141                         * mapping. However, page->index will not change
2142                         * because we have a reference on the page.
2143                         */
2144                        if (page->index > end)
2145                                goto out;
2146
2147                        *done_index = page->index + 1;
2148
2149                        /*
2150                         * If we can't merge this page, and we have
2151                         * accumulated an contiguous region, write it
2152                         */
2153                        if ((mpd->next_page != page->index) &&
2154                            (mpd->next_page != mpd->first_page)) {
2155                                mpage_da_map_and_submit(mpd);
2156                                goto ret_extent_tail;
2157                        }
2158
2159                        lock_page(page);
2160
2161                        /*
2162                         * If the page is no longer dirty, or its
2163                         * mapping no longer corresponds to inode we
2164                         * are writing (which means it has been
2165                         * truncated or invalidated), or the page is
2166                         * already under writeback and we are not
2167                         * doing a data integrity writeback, skip the page
2168                         */
2169                        if (!PageDirty(page) ||
2170                            (PageWriteback(page) &&
2171                             (wbc->sync_mode == WB_SYNC_NONE)) ||
2172                            unlikely(page->mapping != mapping)) {
2173                                unlock_page(page);
2174                                continue;
2175                        }
2176
2177                        wait_on_page_writeback(page);
2178                        BUG_ON(PageWriteback(page));
2179
2180                        if (mpd->next_page != page->index)
2181                                mpd->first_page = page->index;
2182                        mpd->next_page = page->index + 1;
2183                        logical = (sector_t) page->index <<
2184                                (PAGE_CACHE_SHIFT - inode->i_blkbits);
2185
2186                        if (!page_has_buffers(page)) {
2187                                mpage_add_bh_to_extent(mpd, logical,
2188                                                       PAGE_CACHE_SIZE,
2189                                                       (1 << BH_Dirty) | (1 << BH_Uptodate));
2190                                if (mpd->io_done)
2191                                        goto ret_extent_tail;
2192                        } else {
2193                                /*
2194                                 * Page with regular buffer heads,
2195                                 * just add all dirty ones
2196                                 */
2197                                head = page_buffers(page);
2198                                bh = head;
2199                                do {
2200                                        BUG_ON(buffer_locked(bh));
2201                                        /*
2202                                         * We need to try to allocate
2203                                         * unmapped blocks in the same page.
2204                                         * Otherwise we won't make progress
2205                                         * with the page in ext4_writepage
2206                                         */
2207                                        if (ext4_bh_delay_or_unwritten(NULL, bh)) {
2208                                                mpage_add_bh_to_extent(mpd, logical,
2209                                                                       bh->b_size,
2210                                                                       bh->b_state);
2211                                                if (mpd->io_done)
2212                                                        goto ret_extent_tail;
2213                                        } else if (buffer_dirty(bh) && (buffer_mapped(bh))) {
2214                                                /*
2215                                                 * mapped dirty buffer. We need
2216                                                 * to update the b_state
2217                                                 * because we look at b_state
2218                                                 * in mpage_da_map_blocks.  We
2219                                                 * don't update b_size because
2220                                                 * if we find an unmapped
2221                                                 * buffer_head later we need to
2222                                                 * use the b_state flag of that
2223                                                 * buffer_head.
2224                                                 */
2225                                                if (mpd->b_size == 0)
2226                                                        mpd->b_state = bh->b_state & BH_FLAGS;
2227                                        }
2228                                        logical++;
2229                                } while ((bh = bh->b_this_page) != head);
2230                        }
2231
2232                        if (nr_to_write > 0) {
2233                                nr_to_write--;
2234                                if (nr_to_write == 0 &&
2235                                    wbc->sync_mode == WB_SYNC_NONE)
2236                                        /*
2237                                         * We stop writing back only if we are
2238                                         * not doing integrity sync. In case of
2239                                         * integrity sync we have to keep going
2240                                         * because someone may be concurrently
2241                                         * dirtying pages, and we might have
2242                                         * synced a lot of newly appeared dirty
2243                                         * pages, but have not synced all of the
2244                                         * old dirty pages.
2245                                         */
2246                                        goto out;
2247                        }
2248                }
2249                pagevec_release(&pvec);
2250                cond_resched();
2251        }
2252        return 0;
2253ret_extent_tail:
2254        ret = MPAGE_DA_EXTENT_TAIL;
2255out:
2256        pagevec_release(&pvec);
2257        cond_resched();
2258        return ret;
2259}
2260
2261
2262static int ext4_da_writepages(struct address_space *mapping,
2263                              struct writeback_control *wbc)
2264{
2265        pgoff_t index;
2266        int range_whole = 0;
2267        handle_t *handle = NULL;
2268        struct mpage_da_data mpd;
2269        struct inode *inode = mapping->host;
2270        int pages_written = 0;
2271        unsigned int max_pages;
2272        int range_cyclic, cycled = 1, io_done = 0;
2273        int needed_blocks, ret = 0;
2274        long desired_nr_to_write, nr_to_writebump = 0;
2275        loff_t range_start = wbc->range_start;
2276        struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2277        pgoff_t done_index = 0;
2278        pgoff_t end;
2279        struct blk_plug plug;
2280
2281        trace_ext4_da_writepages(inode, wbc);
2282
2283        /*
2284         * No pages to write? This is mainly a kludge to avoid starting
2285         * a transaction for special inodes like journal inode on last iput()
2286         * because that could violate lock ordering on umount
2287         */
2288        if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2289                return 0;
2290
2291        /*
2292         * If the filesystem has aborted, it is read-only, so return
2293         * right away instead of dumping stack traces later on that
2294         * will obscure the real source of the problem.  We test
2295         * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2296         * the latter could be true if the filesystem is mounted
2297         * read-only, and in that case, ext4_da_writepages should
2298         * *never* be called, so if that ever happens, we would want
2299         * the stack trace.
2300         */
2301        if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2302                return -EROFS;
2303
2304        if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2305                range_whole = 1;
2306
2307        range_cyclic = wbc->range_cyclic;
2308        if (wbc->range_cyclic) {
2309                index = mapping->writeback_index;
2310                if (index)
2311                        cycled = 0;
2312                wbc->range_start = index << PAGE_CACHE_SHIFT;
2313                wbc->range_end  = LLONG_MAX;
2314                wbc->range_cyclic = 0;
2315                end = -1;
2316        } else {
2317                index = wbc->range_start >> PAGE_CACHE_SHIFT;
2318                end = wbc->range_end >> PAGE_CACHE_SHIFT;
2319        }
2320
2321        /*
2322         * This works around two forms of stupidity.  The first is in
2323         * the writeback code, which caps the maximum number of pages
2324         * written to be 1024 pages.  This is wrong on multiple
2325         * levels; different architectues have a different page size,
2326         * which changes the maximum amount of data which gets
2327         * written.  Secondly, 4 megabytes is way too small.  XFS
2328         * forces this value to be 16 megabytes by multiplying
2329         * nr_to_write parameter by four, and then relies on its
2330         * allocator to allocate larger extents to make them
2331         * contiguous.  Unfortunately this brings us to the second
2332         * stupidity, which is that ext4's mballoc code only allocates
2333         * at most 2048 blocks.  So we force contiguous writes up to
2334         * the number of dirty blocks in the inode, or
2335         * sbi->max_writeback_mb_bump whichever is smaller.
2336         */
2337        max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT);
2338        if (!range_cyclic && range_whole) {
2339                if (wbc->nr_to_write == LONG_MAX)
2340                        desired_nr_to_write = wbc->nr_to_write;
2341                else
2342                        desired_nr_to_write = wbc->nr_to_write * 8;
2343        } else
2344                desired_nr_to_write = ext4_num_dirty_pages(inode, index,
2345                                                           max_pages);
2346        if (desired_nr_to_write > max_pages)
2347                desired_nr_to_write = max_pages;
2348
2349        if (wbc->nr_to_write < desired_nr_to_write) {
2350                nr_to_writebump = desired_nr_to_write - wbc->nr_to_write;
2351                wbc->nr_to_write = desired_nr_to_write;
2352        }
2353
2354retry:
2355        if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2356                tag_pages_for_writeback(mapping, index, end);
2357
2358        blk_start_plug(&plug);
2359        while (!ret && wbc->nr_to_write > 0) {
2360
2361                /*
2362                 * we  insert one extent at a time. So we need
2363                 * credit needed for single extent allocation.
2364                 * journalled mode is currently not supported
2365                 * by delalloc
2366                 */
2367                BUG_ON(ext4_should_journal_data(inode));
2368                needed_blocks = ext4_da_writepages_trans_blocks(inode);
2369
2370                /* start a new transaction*/
2371                handle = ext4_journal_start(inode, needed_blocks);
2372                if (IS_ERR(handle)) {
2373                        ret = PTR_ERR(handle);
2374                        ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2375                               "%ld pages, ino %lu; err %d", __func__,
2376                                wbc->nr_to_write, inode->i_ino, ret);
2377                        blk_finish_plug(&plug);
2378                        goto out_writepages;
2379                }
2380
2381                /*
2382                 * Now call write_cache_pages_da() to find the next
2383                 * contiguous region of logical blocks that need
2384                 * blocks to be allocated by ext4 and submit them.
2385                 */
2386                ret = write_cache_pages_da(mapping, wbc, &mpd, &done_index);
2387                /*
2388                 * If we have a contiguous extent of pages and we
2389                 * haven't done the I/O yet, map the blocks and submit
2390                 * them for I/O.
2391                 */
2392                if (!mpd.io_done && mpd.next_page != mpd.first_page) {
2393                        mpage_da_map_and_submit(&mpd);
2394                        ret = MPAGE_DA_EXTENT_TAIL;
2395                }
2396                trace_ext4_da_write_pages(inode, &mpd);
2397                wbc->nr_to_write -= mpd.pages_written;
2398
2399                ext4_journal_stop(handle);
2400
2401                if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
2402                        /* commit the transaction which would
2403                         * free blocks released in the transaction
2404                         * and try again
2405                         */
2406                        jbd2_journal_force_commit_nested(sbi->s_journal);
2407                        ret = 0;
2408                } else if (ret == MPAGE_DA_EXTENT_TAIL) {
2409                        /*
2410                         * Got one extent now try with rest of the pages.
2411                         * If mpd.retval is set -EIO, journal is aborted.
2412                         * So we don't need to write any more.
2413                         */
2414                        pages_written += mpd.pages_written;
2415                        ret = mpd.retval;
2416                        io_done = 1;
2417                } else if (wbc->nr_to_write)
2418                        /*
2419                         * There is no more writeout needed
2420                         * or we requested for a noblocking writeout
2421                         * and we found the device congested
2422                         */
2423                        break;
2424        }
2425        blk_finish_plug(&plug);
2426        if (!io_done && !cycled) {
2427                cycled = 1;
2428                index = 0;
2429                wbc->range_start = index << PAGE_CACHE_SHIFT;
2430                wbc->range_end  = mapping->writeback_index - 1;
2431                goto retry;
2432        }
2433
2434        /* Update index */
2435        wbc->range_cyclic = range_cyclic;
2436        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2437                /*
2438                 * set the writeback_index so that range_cyclic
2439                 * mode will write it back later
2440                 */
2441                mapping->writeback_index = done_index;
2442
2443out_writepages:
2444        wbc->nr_to_write -= nr_to_writebump;
2445        wbc->range_start = range_start;
2446        trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
2447        return ret;
2448}
2449
2450#define FALL_BACK_TO_NONDELALLOC 1
2451static int ext4_nonda_switch(struct super_block *sb)
2452{
2453        s64 free_blocks, dirty_blocks;
2454        struct ext4_sb_info *sbi = EXT4_SB(sb);
2455
2456        /*
2457         * switch to non delalloc mode if we are running low
2458         * on free block. The free block accounting via percpu
2459         * counters can get slightly wrong with percpu_counter_batch getting
2460         * accumulated on each CPU without updating global counters
2461         * Delalloc need an accurate free block accounting. So switch
2462         * to non delalloc when we are near to error range.
2463         */
2464        free_blocks  = EXT4_C2B(sbi,
2465                percpu_counter_read_positive(&sbi->s_freeclusters_counter));
2466        dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
2467        /*
2468         * Start pushing delalloc when 1/2 of free blocks are dirty.
2469         */
2470        if (dirty_blocks && (free_blocks < 2 * dirty_blocks) &&
2471            !writeback_in_progress(sb->s_bdi) &&
2472            down_read_trylock(&sb->s_umount)) {
2473                writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
2474                up_read(&sb->s_umount);
2475        }
2476
2477        if (2 * free_blocks < 3 * dirty_blocks ||
2478                free_blocks < (dirty_blocks + EXT4_FREECLUSTERS_WATERMARK)) {
2479                /*
2480                 * free block count is less than 150% of dirty blocks
2481                 * or free blocks is less than watermark
2482                 */
2483                return 1;
2484        }
2485        return 0;
2486}
2487
2488static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
2489                               loff_t pos, unsigned len, unsigned flags,
2490                               struct page **pagep, void **fsdata)
2491{
2492        int ret, retries = 0;
2493        struct page *page;
2494        pgoff_t index;
2495        struct inode *inode = mapping->host;
2496        handle_t *handle;
2497
2498        index = pos >> PAGE_CACHE_SHIFT;
2499
2500        if (ext4_nonda_switch(inode->i_sb)) {
2501                *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
2502                return ext4_write_begin(file, mapping, pos,
2503                                        len, flags, pagep, fsdata);
2504        }
2505        *fsdata = (void *)0;
2506        trace_ext4_da_write_begin(inode, pos, len, flags);
2507retry:
2508        /*
2509         * With delayed allocation, we don't log the i_disksize update
2510         * if there is delayed block allocation. But we still need
2511         * to journalling the i_disksize update if writes to the end
2512         * of file which has an already mapped buffer.
2513         */
2514        handle = ext4_journal_start(inode, 1);
2515        if (IS_ERR(handle)) {
2516                ret = PTR_ERR(handle);
2517                goto out;
2518        }
2519        /* We cannot recurse into the filesystem as the transaction is already
2520         * started */
2521        flags |= AOP_FLAG_NOFS;
2522
2523        page = grab_cache_page_write_begin(mapping, index, flags);
2524        if (!page) {
2525                ext4_journal_stop(handle);
2526                ret = -ENOMEM;
2527                goto out;
2528        }
2529        *pagep = page;
2530
2531        ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
2532        if (ret < 0) {
2533                unlock_page(page);
2534                ext4_journal_stop(handle);
2535                page_cache_release(page);
2536                /*
2537                 * block_write_begin may have instantiated a few blocks
2538                 * outside i_size.  Trim these off again. Don't need
2539                 * i_size_read because we hold i_mutex.
2540                 */
2541                if (pos + len > inode->i_size)
2542                        ext4_truncate_failed_write(inode);
2543        }
2544
2545        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
2546                goto retry;
2547out:
2548        return ret;
2549}
2550
2551/*
2552 * Check if we should update i_disksize
2553 * when write to the end of file but not require block allocation
2554 */
2555static int ext4_da_should_update_i_disksize(struct page *page,
2556                                            unsigned long offset)
2557{
2558        struct buffer_head *bh;
2559        struct inode *inode = page->mapping->host;
2560        unsigned int idx;
2561        int i;
2562
2563        bh = page_buffers(page);
2564        idx = offset >> inode->i_blkbits;
2565
2566        for (i = 0; i < idx; i++)
2567                bh = bh->b_this_page;
2568
2569        if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
2570                return 0;
2571        return 1;
2572}
2573
2574static int ext4_da_write_end(struct file *file,
2575                             struct address_space *mapping,
2576                             loff_t pos, unsigned len, unsigned copied,
2577                             struct page *page, void *fsdata)
2578{
2579        struct inode *inode = mapping->host;
2580        int ret = 0, ret2;
2581        handle_t *handle = ext4_journal_current_handle();
2582        loff_t new_i_size;
2583        unsigned long start, end;
2584        int write_mode = (int)(unsigned long)fsdata;
2585
2586        if (write_mode == FALL_BACK_TO_NONDELALLOC) {
2587                switch (ext4_inode_journal_mode(inode)) {
2588                case EXT4_INODE_ORDERED_DATA_MODE:
2589                        return ext4_ordered_write_end(file, mapping, pos,
2590                                        len, copied, page, fsdata);
2591                case EXT4_INODE_WRITEBACK_DATA_MODE:
2592                        return ext4_writeback_write_end(file, mapping, pos,
2593                                        len, copied, page, fsdata);
2594                default:
2595                        BUG();
2596                }
2597        }
2598
2599        trace_ext4_da_write_end(inode, pos, len, copied);
2600        start = pos & (PAGE_CACHE_SIZE - 1);
2601        end = start + copied - 1;
2602
2603        /*
2604         * generic_write_end() will run mark_inode_dirty() if i_size
2605         * changes.  So let's piggyback the i_disksize mark_inode_dirty
2606         * into that.
2607         */
2608
2609        new_i_size = pos + copied;
2610        if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
2611                if (ext4_da_should_update_i_disksize(page, end)) {
2612                        down_write(&EXT4_I(inode)->i_data_sem);
2613                        if (new_i_size > EXT4_I(inode)->i_disksize) {
2614                                /*
2615                                 * Updating i_disksize when extending file
2616                                 * without needing block allocation
2617                                 */
2618                                if (ext4_should_order_data(inode))
2619                                        ret = ext4_jbd2_file_inode(handle,
2620                                                                   inode);
2621
2622                                EXT4_I(inode)->i_disksize = new_i_size;
2623                        }
2624                        up_write(&EXT4_I(inode)->i_data_sem);
2625                        /* We need to mark inode dirty even if
2626                         * new_i_size is less that inode->i_size
2627                         * bu greater than i_disksize.(hint delalloc)
2628                         */
2629                        ext4_mark_inode_dirty(handle, inode);
2630                }
2631        }
2632        ret2 = generic_write_end(file, mapping, pos, len, copied,
2633                                                        page, fsdata);
2634        copied = ret2;
2635        if (ret2 < 0)
2636                ret = ret2;
2637        ret2 = ext4_journal_stop(handle);
2638        if (!ret)
2639                ret = ret2;
2640
2641        return ret ? ret : copied;
2642}
2643
2644static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
2645{
2646        /*
2647         * Drop reserved blocks
2648         */
2649        BUG_ON(!PageLocked(page));
2650        if (!page_has_buffers(page))
2651                goto out;
2652
2653        ext4_da_page_release_reservation(page, offset);
2654
2655out:
2656        ext4_invalidatepage(page, offset);
2657
2658        return;
2659}
2660
2661/*
2662 * Force all delayed allocation blocks to be allocated for a given inode.
2663 */
2664int ext4_alloc_da_blocks(struct inode *inode)
2665{
2666        trace_ext4_alloc_da_blocks(inode);
2667
2668        if (!EXT4_I(inode)->i_reserved_data_blocks &&
2669            !EXT4_I(inode)->i_reserved_meta_blocks)
2670                return 0;
2671
2672        /*
2673         * We do something simple for now.  The filemap_flush() will
2674         * also start triggering a write of the data blocks, which is
2675         * not strictly speaking necessary (and for users of
2676         * laptop_mode, not even desirable).  However, to do otherwise
2677         * would require replicating code paths in:
2678         *
2679         * ext4_da_writepages() ->
2680         *    write_cache_pages() ---> (via passed in callback function)
2681         *        __mpage_da_writepage() -->
2682         *           mpage_add_bh_to_extent()
2683         *           mpage_da_map_blocks()
2684         *
2685         * The problem is that write_cache_pages(), located in
2686         * mm/page-writeback.c, marks pages clean in preparation for
2687         * doing I/O, which is not desirable if we're not planning on
2688         * doing I/O at all.
2689         *
2690         * We could call write_cache_pages(), and then redirty all of
2691         * the pages by calling redirty_page_for_writepage() but that
2692         * would be ugly in the extreme.  So instead we would need to
2693         * replicate parts of the code in the above functions,
2694         * simplifying them because we wouldn't actually intend to
2695         * write out the pages, but rather only collect contiguous
2696         * logical block extents, call the multi-block allocator, and
2697         * then update the buffer heads with the block allocations.
2698         *
2699         * For now, though, we'll cheat by calling filemap_flush(),
2700         * which will map the blocks, and start the I/O, but not
2701         * actually wait for the I/O to complete.
2702         */
2703        return filemap_flush(inode->i_mapping);
2704}
2705
2706/*
2707 * bmap() is special.  It gets used by applications such as lilo and by
2708 * the swapper to find the on-disk block of a specific piece of data.
2709 *
2710 * Naturally, this is dangerous if the block concerned is still in the
2711 * journal.  If somebody makes a swapfile on an ext4 data-journaling
2712 * filesystem and enables swap, then they may get a nasty shock when the
2713 * data getting swapped to that swapfile suddenly gets overwritten by
2714 * the original zero's written out previously to the journal and
2715 * awaiting writeback in the kernel's buffer cache.
2716 *
2717 * So, if we see any bmap calls here on a modified, data-journaled file,
2718 * take extra steps to flush any blocks which might be in the cache.
2719 */
2720static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
2721{
2722        struct inode *inode = mapping->host;
2723        journal_t *journal;
2724        int err;
2725
2726        if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
2727                        test_opt(inode->i_sb, DELALLOC)) {
2728                /*
2729                 * With delalloc we want to sync the file
2730                 * so that we can make sure we allocate
2731                 * blocks for file
2732                 */
2733                filemap_write_and_wait(mapping);
2734        }
2735
2736        if (EXT4_JOURNAL(inode) &&
2737            ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
2738                /*
2739                 * This is a REALLY heavyweight approach, but the use of
2740                 * bmap on dirty files is expected to be extremely rare:
2741                 * only if we run lilo or swapon on a freshly made file
2742                 * do we expect this to happen.
2743                 *
2744                 * (bmap requires CAP_SYS_RAWIO so this does not
2745                 * represent an unprivileged user DOS attack --- we'd be
2746                 * in trouble if mortal users could trigger this path at
2747                 * will.)
2748                 *
2749                 * NB. EXT4_STATE_JDATA is not set on files other than
2750                 * regular files.  If somebody wants to bmap a directory
2751                 * or symlink and gets confused because the buffer
2752                 * hasn't yet been flushed to disk, they deserve
2753                 * everything they get.
2754                 */
2755
2756                ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
2757                journal = EXT4_JOURNAL(inode);
2758                jbd2_journal_lock_updates(journal);
2759                err = jbd2_journal_flush(journal);
2760                jbd2_journal_unlock_updates(journal);
2761
2762                if (err)
2763                        return 0;
2764        }
2765
2766        return generic_block_bmap(mapping, block, ext4_get_block);
2767}
2768
2769static int ext4_readpage(struct file *file, struct page *page)
2770{
2771        trace_ext4_readpage(page);
2772        return mpage_readpage(page, ext4_get_block);
2773}
2774
2775static int
2776ext4_readpages(struct file *file, struct address_space *mapping,
2777                struct list_head *pages, unsigned nr_pages)
2778{
2779        return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
2780}
2781
2782static void ext4_invalidatepage_free_endio(struct page *page, unsigned long offset)
2783{
2784        struct buffer_head *head, *bh;
2785        unsigned int curr_off = 0;
2786
2787        if (!page_has_buffers(page))
2788                return;
2789        head = bh = page_buffers(page);
2790        do {
2791                if (offset <= curr_off && test_clear_buffer_uninit(bh)
2792                                        && bh->b_private) {
2793                        ext4_free_io_end(bh->b_private);
2794                        bh->b_private = NULL;
2795                        bh->b_end_io = NULL;
2796                }
2797                curr_off = curr_off + bh->b_size;
2798                bh = bh->b_this_page;
2799        } while (bh != head);
2800}
2801
2802static void ext4_invalidatepage(struct page *page, unsigned long offset)
2803{
2804        journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2805
2806        trace_ext4_invalidatepage(page, offset);
2807
2808        /*
2809         * free any io_end structure allocated for buffers to be discarded
2810         */
2811        if (ext4_should_dioread_nolock(page->mapping->host))
2812                ext4_invalidatepage_free_endio(page, offset);
2813        /*
2814         * If it's a full truncate we just forget about the pending dirtying
2815         */
2816        if (offset == 0)
2817                ClearPageChecked(page);
2818
2819        if (journal)
2820                jbd2_journal_invalidatepage(journal, page, offset);
2821        else
2822                block_invalidatepage(page, offset);
2823}
2824
2825static int ext4_releasepage(struct page *page, gfp_t wait)
2826{
2827        journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2828
2829        trace_ext4_releasepage(page);
2830
2831        WARN_ON(PageChecked(page));
2832        if (!page_has_buffers(page))
2833                return 0;
2834        if (journal)
2835                return jbd2_journal_try_to_free_buffers(journal, page, wait);
2836        else
2837                return try_to_free_buffers(page);
2838}
2839
2840/*
2841 * ext4_get_block used when preparing for a DIO write or buffer write.
2842 * We allocate an uinitialized extent if blocks haven't been allocated.
2843 * The extent will be converted to initialized after the IO is complete.
2844 */
2845static int ext4_get_block_write(struct inode *inode, sector_t iblock,
2846                   struct buffer_head *bh_result, int create)
2847{
2848        ext4_debug("ext4_get_block_write: inode %lu, create flag %d\n",
2849                   inode->i_ino, create);
2850        return _ext4_get_block(inode, iblock, bh_result,
2851                               EXT4_GET_BLOCKS_IO_CREATE_EXT);
2852}
2853
2854static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
2855                   struct buffer_head *bh_result, int flags)
2856{
2857        handle_t *handle = ext4_journal_current_handle();
2858        struct ext4_map_blocks map;
2859        int ret = 0;
2860
2861        ext4_debug("ext4_get_block_write_nolock: inode %lu, flag %d\n",
2862                   inode->i_ino, flags);
2863
2864        flags = EXT4_GET_BLOCKS_NO_LOCK;
2865
2866        map.m_lblk = iblock;
2867        map.m_len = bh_result->b_size >> inode->i_blkbits;
2868
2869        ret = ext4_map_blocks(handle, inode, &map, flags);
2870        if (ret > 0) {
2871                map_bh(bh_result, inode->i_sb, map.m_pblk);
2872                bh_result->b_state = (bh_result->b_state & ~EXT4_MAP_FLAGS) |
2873                                        map.m_flags;
2874                bh_result->b_size = inode->i_sb->s_blocksize * map.m_len;
2875                ret = 0;
2876        }
2877        return ret;
2878}
2879
2880static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
2881                            ssize_t size, void *private, int ret,
2882                            bool is_async)
2883{
2884        struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
2885        ext4_io_end_t *io_end = iocb->private;
2886
2887        /* if not async direct IO or dio with 0 bytes write, just return */
2888        if (!io_end || !size)
2889                goto out;
2890
2891        ext_debug("ext4_end_io_dio(): io_end 0x%p "
2892                  "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
2893                  iocb->private, io_end->inode->i_ino, iocb, offset,
2894                  size);
2895
2896        iocb->private = NULL;
2897
2898        /* if not aio dio with unwritten extents, just free io and return */
2899        if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
2900                ext4_free_io_end(io_end);
2901out:
2902                if (is_async)
2903                        aio_complete(iocb, ret, 0);
2904                inode_dio_done(inode);
2905                return;
2906        }
2907
2908        io_end->offset = offset;
2909        io_end->size = size;
2910        if (is_async) {
2911                io_end->iocb = iocb;
2912                io_end->result = ret;
2913        }
2914
2915        ext4_add_complete_io(io_end);
2916}
2917
2918static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
2919{
2920        ext4_io_end_t *io_end = bh->b_private;
2921        struct inode *inode;
2922
2923        if (!test_clear_buffer_uninit(bh) || !io_end)
2924                goto out;
2925
2926        if (!(io_end->inode->i_sb->s_flags & MS_ACTIVE)) {
2927                ext4_msg(io_end->inode->i_sb, KERN_INFO,
2928                         "sb umounted, discard end_io request for inode %lu",
2929                         io_end->inode->i_ino);
2930                ext4_free_io_end(io_end);
2931                goto out;
2932        }
2933
2934        /*
2935         * It may be over-defensive here to check EXT4_IO_END_UNWRITTEN now,
2936         * but being more careful is always safe for the future change.
2937         */
2938        inode = io_end->inode;
2939        ext4_set_io_unwritten_flag(inode, io_end);
2940        ext4_add_complete_io(io_end);
2941out:
2942        bh->b_private = NULL;
2943        bh->b_end_io = NULL;
2944        clear_buffer_uninit(bh);
2945        end_buffer_async_write(bh, uptodate);
2946}
2947
2948static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode)
2949{
2950        ext4_io_end_t *io_end;
2951        struct page *page = bh->b_page;
2952        loff_t offset = (sector_t)page->index << PAGE_CACHE_SHIFT;
2953        size_t size = bh->b_size;
2954
2955retry:
2956        io_end = ext4_init_io_end(inode, GFP_ATOMIC);
2957        if (!io_end) {
2958                pr_warn_ratelimited("%s: allocation fail\n", __func__);
2959                schedule();
2960                goto retry;
2961        }
2962        io_end->offset = offset;
2963        io_end->size = size;
2964        /*
2965         * We need to hold a reference to the page to make sure it
2966         * doesn't get evicted before ext4_end_io_work() has a chance
2967         * to convert the extent from written to unwritten.
2968         */
2969        io_end->page = page;
2970        get_page(io_end->page);
2971
2972        bh->b_private = io_end;
2973        bh->b_end_io = ext4_end_io_buffer_write;
2974        return 0;
2975}
2976
2977/*
2978 * For ext4 extent files, ext4 will do direct-io write to holes,
2979 * preallocated extents, and those write extend the file, no need to
2980 * fall back to buffered IO.
2981 *
2982 * For holes, we fallocate those blocks, mark them as uninitialized
2983 * If those blocks were preallocated, we mark sure they are splited, but
2984 * still keep the range to write as uninitialized.
2985 *
2986 * The unwrritten extents will be converted to written when DIO is completed.
2987 * For async direct IO, since the IO may still pending when return, we
2988 * set up an end_io call back function, which will do the conversion
2989 * when async direct IO completed.
2990 *
2991 * If the O_DIRECT write will extend the file then add this inode to the
2992 * orphan list.  So recovery will truncate it back to the original size
2993 * if the machine crashes during the write.
2994 *
2995 */
2996static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
2997                              const struct iovec *iov, loff_t offset,
2998                              unsigned long nr_segs)
2999{
3000        struct file *file = iocb->ki_filp;
3001        struct inode *inode = file->f_mapping->host;
3002        ssize_t ret;
3003        size_t count = iov_length(iov, nr_segs);
3004
3005        loff_t final_size = offset + count;
3006        if (rw == WRITE && final_size <= inode->i_size) {
3007                int overwrite = 0;
3008
3009                BUG_ON(iocb->private == NULL);
3010
3011                /* If we do a overwrite dio, i_mutex locking can be released */
3012                overwrite = *((int *)iocb->private);
3013
3014                if (overwrite) {
3015                        atomic_inc(&inode->i_dio_count);
3016                        down_read(&EXT4_I(inode)->i_data_sem);
3017                        mutex_unlock(&inode->i_mutex);
3018                }
3019
3020                /*
3021                 * We could direct write to holes and fallocate.
3022                 *
3023                 * Allocated blocks to fill the hole are marked as uninitialized
3024                 * to prevent parallel buffered read to expose the stale data
3025                 * before DIO complete the data IO.
3026                 *
3027                 * As to previously fallocated extents, ext4 get_block
3028                 * will just simply mark the buffer mapped but still
3029                 * keep the extents uninitialized.
3030                 *
3031                 * for non AIO case, we will convert those unwritten extents
3032                 * to written after return back from blockdev_direct_IO.
3033                 *
3034                 * for async DIO, the conversion needs to be defered when
3035                 * the IO is completed. The ext4 end_io callback function
3036                 * will be called to take care of the conversion work.
3037                 * Here for async case, we allocate an io_end structure to
3038                 * hook to the iocb.
3039                 */
3040                iocb->private = NULL;
3041                ext4_inode_aio_set(inode, NULL);
3042                if (!is_sync_kiocb(iocb)) {
3043                        ext4_io_end_t *io_end =
3044                                ext4_init_io_end(inode, GFP_NOFS);
3045                        if (!io_end) {
3046                                ret = -ENOMEM;
3047                                goto retake_lock;
3048                        }
3049                        io_end->flag |= EXT4_IO_END_DIRECT;
3050                        iocb->private = io_end;
3051                        /*
3052                         * we save the io structure for current async
3053                         * direct IO, so that later ext4_map_blocks()
3054                         * could flag the io structure whether there
3055                         * is a unwritten extents needs to be converted
3056                         * when IO is completed.
3057                         */
3058                        ext4_inode_aio_set(inode, io_end);
3059                }
3060
3061                if (overwrite)
3062                        ret = __blockdev_direct_IO(rw, iocb, inode,
3063                                                 inode->i_sb->s_bdev, iov,
3064                                                 offset, nr_segs,
3065                                                 ext4_get_block_write_nolock,
3066                                                 ext4_end_io_dio,
3067                                                 NULL,
3068                                                 0);
3069                else
3070                        ret = __blockdev_direct_IO(rw, iocb, inode,
3071                                                 inode->i_sb->s_bdev, iov,
3072                                                 offset, nr_segs,
3073                                                 ext4_get_block_write,
3074                                                 ext4_end_io_dio,
3075                                                 NULL,
3076                                                 DIO_LOCKING);
3077                if (iocb->private)
3078                        ext4_inode_aio_set(inode, NULL);
3079                /*
3080                 * The io_end structure takes a reference to the inode,
3081                 * that structure needs to be destroyed and the
3082                 * reference to the inode need to be dropped, when IO is
3083                 * complete, even with 0 byte write, or failed.
3084                 *
3085                 * In the successful AIO DIO case, the io_end structure will be
3086                 * desctroyed and the reference to the inode will be dropped
3087                 * after the end_io call back function is called.
3088                 *
3089                 * In the case there is 0 byte write, or error case, since
3090                 * VFS direct IO won't invoke the end_io call back function,
3091                 * we need to free the end_io structure here.
3092                 */
3093                if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
3094                        ext4_free_io_end(iocb->private);
3095                        iocb->private = NULL;
3096                } else if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
3097                                                EXT4_STATE_DIO_UNWRITTEN)) {
3098                        int err;
3099                        /*
3100                         * for non AIO case, since the IO is already
3101                         * completed, we could do the conversion right here
3102                         */
3103                        err = ext4_convert_unwritten_extents(inode,
3104                                                             offset, ret);
3105                        if (err < 0)
3106                                ret = err;
3107                        ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3108                }
3109
3110        retake_lock:
3111                /* take i_mutex locking again if we do a ovewrite dio */
3112                if (overwrite) {
3113                        inode_dio_done(inode);
3114                        up_read(&EXT4_I(inode)->i_data_sem);
3115                        mutex_lock(&inode->i_mutex);
3116                }
3117
3118                return ret;
3119        }
3120
3121        /* for write the the end of file case, we fall back to old way */
3122        return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
3123}
3124
3125static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
3126                              const struct iovec *iov, loff_t offset,
3127                              unsigned long nr_segs)
3128{
3129        struct file *file = iocb->ki_filp;
3130        struct inode *inode = file->f_mapping->host;
3131        ssize_t ret;
3132
3133        /*
3134         * If we are doing data journalling we don't support O_DIRECT
3135         */
3136        if (ext4_should_journal_data(inode))
3137                return 0;
3138
3139        trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
3140        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3141                ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
3142        else
3143                ret = ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
3144        trace_ext4_direct_IO_exit(inode, offset,
3145                                iov_length(iov, nr_segs), rw, ret);
3146        return ret;
3147}
3148
3149/*
3150 * Pages can be marked dirty completely asynchronously from ext4's journalling
3151 * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
3152 * much here because ->set_page_dirty is called under VFS locks.  The page is
3153 * not necessarily locked.
3154 *
3155 * We cannot just dirty the page and leave attached buffers clean, because the
3156 * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
3157 * or jbddirty because all the journalling code will explode.
3158 *
3159 * So what we do is to mark the page "pending dirty" and next time writepage
3160 * is called, propagate that into the buffers appropriately.
3161 */
3162static int ext4_journalled_set_page_dirty(struct page *page)
3163{
3164        SetPageChecked(page);
3165        return __set_page_dirty_nobuffers(page);
3166}
3167
3168static const struct address_space_operations ext4_ordered_aops = {
3169        .readpage               = ext4_readpage,
3170        .readpages              = ext4_readpages,
3171        .writepage              = ext4_writepage,
3172        .write_begin            = ext4_write_begin,
3173        .write_end              = ext4_ordered_write_end,
3174        .bmap                   = ext4_bmap,
3175        .invalidatepage         = ext4_invalidatepage,
3176        .releasepage            = ext4_releasepage,
3177        .direct_IO              = ext4_direct_IO,
3178        .migratepage            = buffer_migrate_page,
3179        .is_partially_uptodate  = block_is_partially_uptodate,
3180        .error_remove_page      = generic_error_remove_page,
3181};
3182
3183static const struct address_space_operations ext4_writeback_aops = {
3184        .readpage               = ext4_readpage,
3185        .readpages              = ext4_readpages,
3186        .writepage              = ext4_writepage,
3187        .write_begin            = ext4_write_begin,
3188        .write_end              = ext4_writeback_write_end,
3189        .bmap                   = ext4_bmap,
3190        .invalidatepage         = ext4_invalidatepage,
3191        .releasepage            = ext4_releasepage,
3192        .direct_IO              = ext4_direct_IO,
3193        .migratepage            = buffer_migrate_page,
3194        .is_partially_uptodate  = block_is_partially_uptodate,
3195        .error_remove_page      = generic_error_remove_page,
3196};
3197
3198static const struct address_space_operations ext4_journalled_aops = {
3199        .readpage               = ext4_readpage,
3200        .readpages              = ext4_readpages,
3201        .writepage              = ext4_writepage,
3202        .write_begin            = ext4_write_begin,
3203        .write_end              = ext4_journalled_write_end,
3204        .set_page_dirty         = ext4_journalled_set_page_dirty,
3205        .bmap                   = ext4_bmap,
3206        .invalidatepage         = ext4_invalidatepage,
3207        .releasepage            = ext4_releasepage,
3208        .direct_IO              = ext4_direct_IO,
3209        .is_partially_uptodate  = block_is_partially_uptodate,
3210        .error_remove_page      = generic_error_remove_page,
3211};
3212
3213static const struct address_space_operations ext4_da_aops = {
3214        .readpage               = ext4_readpage,
3215        .readpages              = ext4_readpages,
3216        .writepage              = ext4_writepage,
3217        .writepages             = ext4_da_writepages,
3218        .write_begin            = ext4_da_write_begin,
3219        .write_end              = ext4_da_write_end,
3220        .bmap                   = ext4_bmap,
3221        .invalidatepage         = ext4_da_invalidatepage,
3222        .releasepage            = ext4_releasepage,
3223        .direct_IO              = ext4_direct_IO,
3224        .migratepage            = buffer_migrate_page,
3225        .is_partially_uptodate  = block_is_partially_uptodate,
3226        .error_remove_page      = generic_error_remove_page,
3227};
3228
3229void ext4_set_aops(struct inode *inode)
3230{
3231        switch (ext4_inode_journal_mode(inode)) {
3232        case EXT4_INODE_ORDERED_DATA_MODE:
3233                if (test_opt(inode->i_sb, DELALLOC))
3234                        inode->i_mapping->a_ops = &ext4_da_aops;
3235                else
3236                        inode->i_mapping->a_ops = &ext4_ordered_aops;
3237                break;
3238        case EXT4_INODE_WRITEBACK_DATA_MODE:
3239                if (test_opt(inode->i_sb, DELALLOC))
3240                        inode->i_mapping->a_ops = &ext4_da_aops;
3241                else
3242                        inode->i_mapping->a_ops = &ext4_writeback_aops;
3243                break;
3244        case EXT4_INODE_JOURNAL_DATA_MODE:
3245                inode->i_mapping->a_ops = &ext4_journalled_aops;
3246                break;
3247        default:
3248                BUG();
3249        }
3250}
3251
3252
3253/*
3254 * ext4_discard_partial_page_buffers()
3255 * Wrapper function for ext4_discard_partial_page_buffers_no_lock.
3256 * This function finds and locks the page containing the offset
3257 * "from" and passes it to ext4_discard_partial_page_buffers_no_lock.
3258 * Calling functions that already have the page locked should call
3259 * ext4_discard_partial_page_buffers_no_lock directly.
3260 */
3261int ext4_discard_partial_page_buffers(handle_t *handle,
3262                struct address_space *mapping, loff_t from,
3263                loff_t length, int flags)
3264{
3265        struct inode *inode = mapping->host;
3266        struct page *page;
3267        int err = 0;
3268
3269        page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
3270                                   mapping_gfp_mask(mapping) & ~__GFP_FS);
3271        if (!page)
3272                return -ENOMEM;
3273
3274        err = ext4_discard_partial_page_buffers_no_lock(handle, inode, page,
3275                from, length, flags);
3276
3277        unlock_page(page);
3278        page_cache_release(page);
3279        return err;
3280}
3281
3282/*
3283 * ext4_discard_partial_page_buffers_no_lock()
3284 * Zeros a page range of length 'length' starting from offset 'from'.
3285 * Buffer heads that correspond to the block aligned regions of the
3286 * zeroed range will be unmapped.  Unblock aligned regions
3287 * will have the corresponding buffer head mapped if needed so that
3288 * that region of the page can be updated with the partial zero out.
3289 *
3290 * This function assumes that the page has already been  locked.  The
3291 * The range to be discarded must be contained with in the given page.
3292 * If the specified range exceeds the end of the page it will be shortened
3293 * to the end of the page that corresponds to 'from'.  This function is
3294 * appropriate for updating a page and it buffer heads to be unmapped and
3295 * zeroed for blocks that have been either released, or are going to be
3296 * released.
3297 *
3298 * handle: The journal handle
3299 * inode:  The files inode
3300 * page:   A locked page that contains the offset "from"
3301 * from:   The starting byte offset (from the beginning of the file)
3302 *         to begin discarding
3303 * len:    The length of bytes to discard
3304 * flags:  Optional flags that may be used:
3305 *
3306 *         EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED
3307 *         Only zero the regions of the page whose buffer heads
3308 *         have already been unmapped.  This flag is appropriate
3309 *         for updating the contents of a page whose blocks may
3310 *         have already been released, and we only want to zero
3311 *         out the regions that correspond to those released blocks.
3312 *
3313 * Returns zero on success or negative on failure.
3314 */
3315static int ext4_discard_partial_page_buffers_no_lock(handle_t *handle,
3316                struct inode *inode, struct page *page, loff_t from,
3317                loff_t length, int flags)
3318{
3319        ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
3320        unsigned int offset = from & (PAGE_CACHE_SIZE-1);
3321        unsigned int blocksize, max, pos;
3322        ext4_lblk_t iblock;
3323        struct buffer_head *bh;
3324        int err = 0;
3325
3326        blocksize = inode->i_sb->s_blocksize;
3327        max = PAGE_CACHE_SIZE - offset;
3328
3329        if (index != page->index)
3330                return -EINVAL;
3331
3332        /*
3333         * correct length if it does not fall between
3334         * 'from' and the end of the page
3335         */
3336        if (length > max || length < 0)
3337                length = max;
3338
3339        iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
3340
3341        if (!page_has_buffers(page))
3342                create_empty_buffers(page, blocksize, 0);
3343
3344        /* Find the buffer that contains "offset" */
3345        bh = page_buffers(page);
3346        pos = blocksize;
3347        while (offset >= pos) {
3348                bh = bh->b_this_page;
3349                iblock++;
3350                pos += blocksize;
3351        }
3352
3353        pos = offset;
3354        while (pos < offset + length) {
3355                unsigned int end_of_block, range_to_discard;
3356
3357                err = 0;
3358
3359                /* The length of space left to zero and unmap */
3360                range_to_discard = offset + length - pos;
3361
3362                /* The length of space until the end of the block */
3363                end_of_block = blocksize - (pos & (blocksize-1));
3364
3365                /*
3366                 * Do not unmap or zero past end of block
3367                 * for this buffer head
3368                 */
3369                if (range_to_discard > end_of_block)
3370                        range_to_discard = end_of_block;
3371
3372
3373                /*
3374                 * Skip this buffer head if we are only zeroing unampped
3375                 * regions of the page
3376                 */
3377                if (flags & EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED &&
3378                        buffer_mapped(bh))
3379                                goto next;
3380
3381                /* If the range is block aligned, unmap */
3382                if (range_to_discard == blocksize) {
3383                        clear_buffer_dirty(bh);
3384                        bh->b_bdev = NULL;
3385                        clear_buffer_mapped(bh);
3386                        clear_buffer_req(bh);
3387                        clear_buffer_new(bh);
3388                        clear_buffer_delay(bh);
3389                        clear_buffer_unwritten(bh);
3390                        clear_buffer_uptodate(bh);
3391                        zero_user(page, pos, range_to_discard);
3392                        BUFFER_TRACE(bh, "Buffer discarded");
3393                        goto next;
3394                }
3395
3396                /*
3397                 * If this block is not completely contained in the range
3398                 * to be discarded, then it is not going to be released. Because
3399                 * we need to keep this block, we need to make sure this part
3400                 * of the page is uptodate before we modify it by writeing
3401                 * partial zeros on it.
3402                 */
3403                if (!buffer_mapped(bh)) {
3404                        /*
3405                         * Buffer head must be mapped before we can read
3406                         * from the block
3407                         */
3408                        BUFFER_TRACE(bh, "unmapped");
3409                        ext4_get_block(inode, iblock, bh, 0);
3410                        /* unmapped? It's a hole - nothing to do */
3411                        if (!buffer_mapped(bh)) {
3412                                BUFFER_TRACE(bh, "still unmapped");
3413                                goto next;
3414                        }
3415                }
3416
3417                /* Ok, it's mapped. Make sure it's up-to-date */
3418                if (PageUptodate(page))
3419                        set_buffer_uptodate(bh);
3420
3421                if (!buffer_uptodate(bh)) {
3422                        err = -EIO;
3423                        ll_rw_block(READ, 1, &bh);
3424                        wait_on_buffer(bh);
3425                        /* Uhhuh. Read error. Complain and punt.*/
3426                        if (!buffer_uptodate(bh))
3427                                goto next;
3428                }
3429
3430                if (ext4_should_journal_data(inode)) {
3431                        BUFFER_TRACE(bh, "get write access");
3432                        err = ext4_journal_get_write_access(handle, bh);
3433                        if (err)
3434                                goto next;
3435                }
3436
3437                zero_user(page, pos, range_to_discard);
3438
3439                err = 0;
3440                if (ext4_should_journal_data(inode)) {
3441                        err = ext4_handle_dirty_metadata(handle, inode, bh);
3442                } else
3443                        mark_buffer_dirty(bh);
3444
3445                BUFFER_TRACE(bh, "Partial buffer zeroed");
3446next:
3447                bh = bh->b_this_page;
3448                iblock++;
3449                pos += range_to_discard;
3450        }
3451
3452        return err;
3453}
3454
3455int ext4_can_truncate(struct inode *inode)
3456{
3457        if (S_ISREG(inode->i_mode))
3458                return 1;
3459        if (S_ISDIR(inode->i_mode))
3460                return 1;
3461        if (S_ISLNK(inode->i_mode))
3462                return !ext4_inode_is_fast_symlink(inode);
3463        return 0;
3464}
3465
3466/*
3467 * ext4_punch_hole: punches a hole in a file by releaseing the blocks
3468 * associated with the given offset and length
3469 *
3470 * @inode:  File inode
3471 * @offset: The offset where the hole will begin
3472 * @len:    The length of the hole
3473 *
3474 * Returns: 0 on success or negative on failure
3475 */
3476
3477int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
3478{
3479        struct inode *inode = file->f_path.dentry->d_inode;
3480        if (!S_ISREG(inode->i_mode))
3481                return -EOPNOTSUPP;
3482
3483        if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
3484                /* TODO: Add support for non extent hole punching */
3485                return -EOPNOTSUPP;
3486        }
3487
3488        if (EXT4_SB(inode->i_sb)->s_cluster_ratio > 1) {
3489                /* TODO: Add support for bigalloc file systems */
3490                return -EOPNOTSUPP;
3491        }
3492
3493        return ext4_ext_punch_hole(file, offset, length);
3494}
3495
3496/*
3497 * ext4_truncate()
3498 *
3499 * We block out ext4_get_block() block instantiations across the entire
3500 * transaction, and VFS/VM ensures that ext4_truncate() cannot run
3501 * simultaneously on behalf of the same inode.
3502 *
3503 * As we work through the truncate and commit bits of it to the journal there
3504 * is one core, guiding principle: the file's tree must always be consistent on
3505 * disk.  We must be able to restart the truncate after a crash.
3506 *
3507 * The file's tree may be transiently inconsistent in memory (although it
3508 * probably isn't), but whenever we close off and commit a journal transaction,
3509 * the contents of (the filesystem + the journal) must be consistent and
3510 * restartable.  It's pretty simple, really: bottom up, right to left (although
3511 * left-to-right works OK too).
3512 *
3513 * Note that at recovery time, journal replay occurs *before* the restart of
3514 * truncate against the orphan inode list.
3515 *
3516 * The committed inode has the new, desired i_size (which is the same as
3517 * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
3518 * that this inode's truncate did not complete and it will again call
3519 * ext4_truncate() to have another go.  So there will be instantiated blocks
3520 * to the right of the truncation point in a crashed ext4 filesystem.  But
3521 * that's fine - as long as they are linked from the inode, the post-crash
3522 * ext4_truncate() run will find them and release them.
3523 */
3524void ext4_truncate(struct inode *inode)
3525{
3526        trace_ext4_truncate_enter(inode);
3527
3528        if (!ext4_can_truncate(inode))
3529                return;
3530
3531        ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
3532
3533        if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
3534                ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
3535
3536        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3537                ext4_ext_truncate(inode);
3538        else
3539                ext4_ind_truncate(inode);
3540
3541        trace_ext4_truncate_exit(inode);
3542}
3543
3544/*
3545 * ext4_get_inode_loc returns with an extra refcount against the inode's
3546 * underlying buffer_head on success. If 'in_mem' is true, we have all
3547 * data in memory that is needed to recreate the on-disk version of this
3548 * inode.
3549 */
3550static int __ext4_get_inode_loc(struct inode *inode,
3551                                struct ext4_iloc *iloc, int in_mem)
3552{
3553        struct ext4_group_desc  *gdp;
3554        struct buffer_head      *bh;
3555        struct super_block      *sb = inode->i_sb;
3556        ext4_fsblk_t            block;
3557        int                     inodes_per_block, inode_offset;
3558
3559        iloc->bh = NULL;
3560        if (!ext4_valid_inum(sb, inode->i_ino))
3561                return -EIO;
3562
3563        iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
3564        gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
3565        if (!gdp)
3566                return -EIO;
3567
3568        /*
3569         * Figure out the offset within the block group inode table
3570         */
3571        inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
3572        inode_offset = ((inode->i_ino - 1) %
3573                        EXT4_INODES_PER_GROUP(sb));
3574        block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
3575        iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
3576
3577        bh = sb_getblk(sb, block);
3578        if (!bh) {
3579                EXT4_ERROR_INODE_BLOCK(inode, block,
3580                                       "unable to read itable block");
3581                return -EIO;
3582        }
3583        if (!buffer_uptodate(bh)) {
3584                lock_buffer(bh);
3585
3586                /*
3587                 * If the buffer has the write error flag, we have failed
3588                 * to write out another inode in the same block.  In this
3589                 * case, we don't have to read the block because we may
3590                 * read the old inode data successfully.
3591                 */
3592                if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
3593                        set_buffer_uptodate(bh);
3594
3595                if (buffer_uptodate(bh)) {
3596                        /* someone brought it uptodate while we waited */
3597                        unlock_buffer(bh);
3598                        goto has_buffer;
3599                }
3600
3601                /*
3602                 * If we have all information of the inode in memory and this
3603                 * is the only valid inode in the block, we need not read the
3604                 * block.
3605                 */
3606                if (in_mem) {
3607                        struct buffer_head *bitmap_bh;
3608                        int i, start;
3609
3610                        start = inode_offset & ~(inodes_per_block - 1);
3611
3612                        /* Is the inode bitmap in cache? */
3613                        bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
3614                        if (!bitmap_bh)
3615                                goto make_io;
3616
3617                        /*
3618                         * If the inode bitmap isn't in cache then the
3619                         * optimisation may end up performing two reads instead
3620                         * of one, so skip it.
3621                         */
3622                        if (!buffer_uptodate(bitmap_bh)) {
3623                                brelse(bitmap_bh);
3624                                goto make_io;
3625                        }
3626                        for (i = start; i < start + inodes_per_block; i++) {
3627                                if (i == inode_offset)
3628                                        continue;
3629                                if (ext4_test_bit(i, bitmap_bh->b_data))
3630                                        break;
3631                        }
3632                        brelse(bitmap_bh);
3633                        if (i == start + inodes_per_block) {
3634                                /* all other inodes are free, so skip I/O */
3635                                memset(bh->b_data, 0, bh->b_size);
3636                                set_buffer_uptodate(bh);
3637                                unlock_buffer(bh);
3638                                goto has_buffer;
3639                        }
3640                }
3641
3642make_io:
3643                /*
3644                 * If we need to do any I/O, try to pre-readahead extra
3645                 * blocks from the inode table.
3646                 */
3647                if (EXT4_SB(sb)->s_inode_readahead_blks) {
3648                        ext4_fsblk_t b, end, table;
3649                        unsigned num;
3650
3651                        table = ext4_inode_table(sb, gdp);
3652                        /* s_inode_readahead_blks is always a power of 2 */
3653                        b = block & ~(EXT4_SB(sb)->s_inode_readahead_blks-1);
3654                        if (table > b)
3655                                b = table;
3656                        end = b + EXT4_SB(sb)->s_inode_readahead_blks;
3657                        num = EXT4_INODES_PER_GROUP(sb);
3658                        if (ext4_has_group_desc_csum(sb))
3659                                num -= ext4_itable_unused_count(sb, gdp);
3660                        table += num / inodes_per_block;
3661                        if (end > table)
3662                                end = table;
3663                        while (b <= end)
3664                                sb_breadahead(sb, b++);
3665                }
3666
3667                /*
3668                 * There are other valid inodes in the buffer, this inode
3669                 * has in-inode xattrs, or we don't have this inode in memory.
3670                 * Read the block from disk.
3671                 */
3672                trace_ext4_load_inode(inode);
3673                get_bh(bh);
3674                bh->b_end_io = end_buffer_read_sync;
3675                submit_bh(READ | REQ_META | REQ_PRIO, bh);
3676                wait_on_buffer(bh);
3677                if (!buffer_uptodate(bh)) {
3678                        EXT4_ERROR_INODE_BLOCK(inode, block,
3679                                               "unable to read itable block");
3680                        brelse(bh);
3681                        return -EIO;
3682                }
3683        }
3684has_buffer:
3685        iloc->bh = bh;
3686        return 0;
3687}
3688
3689int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
3690{
3691        /* We have all inode data except xattrs in memory here. */
3692        return __ext4_get_inode_loc(inode, iloc,
3693                !ext4_test_inode_state(inode, EXT4_STATE_XATTR));
3694}
3695
3696void ext4_set_inode_flags(struct inode *inode)
3697{
3698        unsigned int flags = EXT4_I(inode)->i_flags;
3699
3700        inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
3701        if (flags & EXT4_SYNC_FL)
3702                inode->i_flags |= S_SYNC;
3703        if (flags & EXT4_APPEND_FL)
3704                inode->i_flags |= S_APPEND;
3705        if (flags & EXT4_IMMUTABLE_FL)
3706                inode->i_flags |= S_IMMUTABLE;
3707        if (flags & EXT4_NOATIME_FL)
3708                inode->i_flags |= S_NOATIME;
3709        if (flags & EXT4_DIRSYNC_FL)
3710                inode->i_flags |= S_DIRSYNC;
3711}
3712
3713/* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
3714void ext4_get_inode_flags(struct ext4_inode_info *ei)
3715{
3716        unsigned int vfs_fl;
3717        unsigned long old_fl, new_fl;
3718
3719        do {
3720                vfs_fl = ei->vfs_inode.i_flags;
3721                old_fl = ei->i_flags;
3722                new_fl = old_fl & ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
3723                                EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|
3724                                EXT4_DIRSYNC_FL);
3725                if (vfs_fl & S_SYNC)
3726                        new_fl |= EXT4_SYNC_FL;
3727                if (vfs_fl & S_APPEND)
3728                        new_fl |= EXT4_APPEND_FL;
3729                if (vfs_fl & S_IMMUTABLE)
3730                        new_fl |= EXT4_IMMUTABLE_FL;
3731                if (vfs_fl & S_NOATIME)
3732                        new_fl |= EXT4_NOATIME_FL;
3733                if (vfs_fl & S_DIRSYNC)
3734                        new_fl |= EXT4_DIRSYNC_FL;
3735        } while (cmpxchg(&ei->i_flags, old_fl, new_fl) != old_fl);
3736}
3737
3738static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
3739                                  struct ext4_inode_info *ei)
3740{
3741        blkcnt_t i_blocks ;
3742        struct inode *inode = &(ei->vfs_inode);
3743        struct super_block *sb = inode->i_sb;
3744
3745        if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
3746                                EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
3747                /* we are using combined 48 bit field */
3748                i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
3749                                        le32_to_cpu(raw_inode->i_blocks_lo);
3750                if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
3751                        /* i_blocks represent file system block size */
3752                        return i_blocks  << (inode->i_blkbits - 9);
3753                } else {
3754                        return i_blocks;
3755                }
3756        } else {
3757                return le32_to_cpu(raw_inode->i_blocks_lo);
3758        }
3759}
3760
3761struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
3762{
3763        struct ext4_iloc iloc;
3764        struct ext4_inode *raw_inode;
3765        struct ext4_inode_info *ei;
3766        struct inode *inode;
3767        journal_t *journal = EXT4_SB(sb)->s_journal;
3768        long ret;
3769        int block;
3770        uid_t i_uid;
3771        gid_t i_gid;
3772
3773        inode = iget_locked(sb, ino);
3774        if (!inode)
3775                return ERR_PTR(-ENOMEM);
3776        if (!(inode->i_state & I_NEW))
3777                return inode;
3778
3779        ei = EXT4_I(inode);
3780        iloc.bh = NULL;
3781
3782        ret = __ext4_get_inode_loc(inode, &iloc, 0);
3783        if (ret < 0)
3784                goto bad_inode;
3785        raw_inode = ext4_raw_inode(&iloc);
3786
3787        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
3788                ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
3789                if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
3790                    EXT4_INODE_SIZE(inode->i_sb)) {
3791                        EXT4_ERROR_INODE(inode, "bad extra_isize (%u != %u)",
3792                                EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize,
3793                                EXT4_INODE_SIZE(inode->i_sb));
3794                        ret = -EIO;
3795                        goto bad_inode;
3796                }
3797        } else
3798                ei->i_extra_isize = 0;
3799
3800        /* Precompute checksum seed for inode metadata */
3801        if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
3802                        EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
3803                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3804                __u32 csum;
3805                __le32 inum = cpu_to_le32(inode->i_ino);
3806                __le32 gen = raw_inode->i_generation;
3807                csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
3808                                   sizeof(inum));
3809                ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
3810                                              sizeof(gen));
3811        }
3812
3813        if (!ext4_inode_csum_verify(inode, raw_inode, ei)) {
3814                EXT4_ERROR_INODE(inode, "checksum invalid");
3815                ret = -EIO;
3816                goto bad_inode;
3817        }
3818
3819        inode->i_mode = le16_to_cpu(raw_inode->i_mode);
3820        i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
3821        i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
3822        if (!(test_opt(inode->i_sb, NO_UID32))) {
3823                i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
3824                i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
3825        }
3826        i_uid_write(inode, i_uid);
3827        i_gid_write(inode, i_gid);
3828        set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
3829
3830        ext4_clear_state_flags(ei);     /* Only relevant on 32-bit archs */
3831        ei->i_dir_start_lookup = 0;
3832        ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
3833        /* We now have enough fields to check if the inode was active or not.
3834         * This is needed because nfsd might try to access dead inodes
3835         * the test is that same one that e2fsck uses
3836         * NeilBrown 1999oct15
3837         */
3838        if (inode->i_nlink == 0) {
3839                if (inode->i_mode == 0 ||
3840                    !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
3841                        /* this inode is deleted */
3842                        ret = -ESTALE;
3843                        goto bad_inode;
3844                }
3845                /* The only unlinked inodes we let through here have
3846                 * valid i_mode and are being read by the orphan
3847                 * recovery code: that's fine, we're about to complete
3848                 * the process of deleting those. */
3849        }
3850        ei->i_flags = le32_to_cpu(raw_inode->i_flags);
3851        inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
3852        ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
3853        if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT))
3854                ei->i_file_acl |=
3855                        ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
3856        inode->i_size = ext4_isize(raw_inode);
3857        ei->i_disksize = inode->i_size;
3858#ifdef CONFIG_QUOTA
3859        ei->i_reserved_quota = 0;
3860#endif
3861        inode->i_generation = le32_to_cpu(raw_inode->i_generation);
3862        ei->i_block_group = iloc.block_group;
3863        ei->i_last_alloc_group = ~0;
3864        /*
3865         * NOTE! The in-memory inode i_data array is in little-endian order
3866         * even on big-endian machines: we do NOT byteswap the block numbers!
3867         */
3868        for (block = 0; block < EXT4_N_BLOCKS; block++)
3869                ei->i_data[block] = raw_inode->i_block[block];
3870        INIT_LIST_HEAD(&ei->i_orphan);
3871
3872        /*
3873         * Set transaction id's of transactions that have to be committed
3874         * to finish f[data]sync. We set them to currently running transaction
3875         * as we cannot be sure that the inode or some of its metadata isn't
3876         * part of the transaction - the inode could have been reclaimed and
3877         * now it is reread from disk.
3878         */
3879        if (journal) {
3880                transaction_t *transaction;
3881                tid_t tid;
3882
3883                read_lock(&journal->j_state_lock);
3884                if (journal->j_running_transaction)
3885                        transaction = journal->j_running_transaction;
3886                else
3887                        transaction = journal->j_committing_transaction;
3888                if (transaction)
3889                        tid = transaction->t_tid;
3890                else
3891                        tid = journal->j_commit_sequence;
3892                read_unlock(&journal->j_state_lock);
3893                ei->i_sync_tid = tid;
3894                ei->i_datasync_tid = tid;
3895        }
3896
3897        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
3898                if (ei->i_extra_isize == 0) {
3899                        /* The extra space is currently unused. Use it. */
3900                        ei->i_extra_isize = sizeof(struct ext4_inode) -
3901                                            EXT4_GOOD_OLD_INODE_SIZE;
3902                } else {
3903                        __le32 *magic = (void *)raw_inode +
3904                                        EXT4_GOOD_OLD_INODE_SIZE +
3905                                        ei->i_extra_isize;
3906                        if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
3907                                ext4_set_inode_state(inode, EXT4_STATE_XATTR);
3908                }
3909        }
3910
3911        EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
3912        EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
3913        EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
3914        EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
3915
3916        inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
3917        if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
3918                if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
3919                        inode->i_version |=
3920                        (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
3921        }
3922
3923        ret = 0;
3924        if (ei->i_file_acl &&
3925            !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
3926                EXT4_ERROR_INODE(inode, "bad extended attribute block %llu",
3927                                 ei->i_file_acl);
3928                ret = -EIO;
3929                goto bad_inode;
3930        } else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
3931                if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
3932                    (S_ISLNK(inode->i_mode) &&
3933                     !ext4_inode_is_fast_symlink(inode)))
3934                        /* Validate extent which is part of inode */
3935                        ret = ext4_ext_check_inode(inode);
3936        } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
3937                   (S_ISLNK(inode->i_mode) &&
3938                    !ext4_inode_is_fast_symlink(inode))) {
3939                /* Validate block references which are part of inode */
3940                ret = ext4_ind_check_inode(inode);
3941        }
3942        if (ret)
3943                goto bad_inode;
3944
3945        if (S_ISREG(inode->i_mode)) {
3946                inode->i_op = &ext4_file_inode_operations;
3947                inode->i_fop = &ext4_file_operations;
3948                ext4_set_aops(inode);
3949        } else if (S_ISDIR(inode->i_mode)) {
3950                inode->i_op = &ext4_dir_inode_operations;
3951                inode->i_fop = &ext4_dir_operations;
3952        } else if (S_ISLNK(inode->i_mode)) {
3953                if (ext4_inode_is_fast_symlink(inode)) {
3954                        inode->i_op = &ext4_fast_symlink_inode_operations;
3955                        nd_terminate_link(ei->i_data, inode->i_size,
3956                                sizeof(ei->i_data) - 1);
3957                } else {
3958                        inode->i_op = &ext4_symlink_inode_operations;
3959                        ext4_set_aops(inode);
3960                }
3961        } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
3962              S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
3963                inode->i_op = &ext4_special_inode_operations;
3964                if (raw_inode->i_block[0])
3965                        init_special_inode(inode, inode->i_mode,
3966                           old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
3967                else
3968                        init_special_inode(inode, inode->i_mode,
3969                           new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
3970        } else {
3971                ret = -EIO;
3972                EXT4_ERROR_INODE(inode, "bogus i_mode (%o)", inode->i_mode);
3973                goto bad_inode;
3974        }
3975        brelse(iloc.bh);
3976        ext4_set_inode_flags(inode);
3977        unlock_new_inode(inode);
3978        return inode;
3979
3980bad_inode:
3981        brelse(iloc.bh);
3982        iget_failed(inode);
3983        return ERR_PTR(ret);
3984}
3985
3986static int ext4_inode_blocks_set(handle_t *handle,
3987                                struct ext4_inode *raw_inode,
3988                                struct ext4_inode_info *ei)
3989{
3990        struct inode *inode = &(ei->vfs_inode);
3991        u64 i_blocks = inode->i_blocks;
3992        struct super_block *sb = inode->i_sb;
3993
3994        if (i_blocks <= ~0U) {
3995                /*
3996                 * i_blocks can be represented in a 32 bit variable
3997                 * as multiple of 512 bytes
3998                 */
3999                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4000                raw_inode->i_blocks_high = 0;
4001                ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4002                return 0;
4003        }
4004        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE))
4005                return -EFBIG;
4006
4007        if (i_blocks <= 0xffffffffffffULL) {
4008                /*
4009                 * i_blocks can be represented in a 48 bit variable
4010                 * as multiple of 512 bytes
4011                 */
4012                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4013                raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4014                ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4015        } else {
4016                ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4017                /* i_block is stored in file system block size */
4018                i_blocks = i_blocks >> (inode->i_blkbits - 9);
4019                raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4020                raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4021        }
4022        return 0;
4023}
4024
4025/*
4026 * Post the struct inode info into an on-disk inode location in the
4027 * buffer-cache.  This gobbles the caller's reference to the
4028 * buffer_head in the inode location struct.
4029 *
4030 * The caller must have write access to iloc->bh.
4031 */
4032static int ext4_do_update_inode(handle_t *handle,
4033                                struct inode *inode,
4034                                struct ext4_iloc *iloc)
4035{
4036        struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
4037        struct ext4_inode_info *ei = EXT4_I(inode);
4038        struct buffer_head *bh = iloc->bh;
4039        int err = 0, rc, block;
4040        int need_datasync = 0;
4041        uid_t i_uid;
4042        gid_t i_gid;
4043
4044        /* For fields not not tracking in the in-memory inode,
4045         * initialise them to zero for new inodes. */
4046        if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
4047                memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
4048
4049        ext4_get_inode_flags(ei);
4050        raw_inode->i_mode = cpu_to_le16(inode->i_mode);
4051        i_uid = i_uid_read(inode);
4052        i_gid = i_gid_read(inode);
4053        if (!(test_opt(inode->i_sb, NO_UID32))) {
4054                raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
4055                raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
4056/*
4057 * Fix up interoperability with old kernels. Otherwise, old inodes get
4058 * re-used with the upper 16 bits of the uid/gid intact
4059 */
4060                if (!ei->i_dtime) {
4061                        raw_inode->i_uid_high =
4062                                cpu_to_le16(high_16_bits(i_uid));
4063                        raw_inode->i_gid_high =
4064                                cpu_to_le16(high_16_bits(i_gid));
4065                } else {
4066                        raw_inode->i_uid_high = 0;
4067                        raw_inode->i_gid_high = 0;
4068                }
4069        } else {
4070                raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
4071                raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(i_gid));
4072                raw_inode->i_uid_high = 0;
4073                raw_inode->i_gid_high = 0;
4074        }
4075        raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
4076
4077        EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
4078        EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
4079        EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
4080        EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
4081
4082        if (ext4_inode_blocks_set(handle, raw_inode, ei))
4083                goto out_brelse;
4084        raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
4085        raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
4086        if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
4087            cpu_to_le32(EXT4_OS_HURD))
4088                raw_inode->i_file_acl_high =
4089                        cpu_to_le16(ei->i_file_acl >> 32);
4090        raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
4091        if (ei->i_disksize != ext4_isize(raw_inode)) {
4092                ext4_isize_set(raw_inode, ei->i_disksize);
4093                need_datasync = 1;
4094        }
4095        if (ei->i_disksize > 0x7fffffffULL) {
4096                struct super_block *sb = inode->i_sb;
4097                if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
4098                                EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
4099                                EXT4_SB(sb)->s_es->s_rev_level ==
4100                                cpu_to_le32(EXT4_GOOD_OLD_REV)) {
4101                        /* If this is the first large file
4102                         * created, add a flag to the superblock.
4103                         */
4104                        err = ext4_journal_get_write_access(handle,
4105                                        EXT4_SB(sb)->s_sbh);
4106                        if (err)
4107                                goto out_brelse;
4108                        ext4_update_dynamic_rev(sb);
4109                        EXT4_SET_RO_COMPAT_FEATURE(sb,
4110                                        EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
4111                        ext4_handle_sync(handle);
4112                        err = ext4_handle_dirty_super(handle, sb);
4113                }
4114        }
4115        raw_inode->i_generation = cpu_to_le32(inode->i_generation);
4116        if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
4117                if (old_valid_dev(inode->i_rdev)) {
4118                        raw_inode->i_block[0] =
4119                                cpu_to_le32(old_encode_dev(inode->i_rdev));
4120                        raw_inode->i_block[1] = 0;
4121                } else {
4122                        raw_inode->i_block[0] = 0;
4123                        raw_inode->i_block[1] =
4124                                cpu_to_le32(new_encode_dev(inode->i_rdev));
4125                        raw_inode->i_block[2] = 0;
4126                }
4127        } else
4128                for (block = 0; block < EXT4_N_BLOCKS; block++)
4129                        raw_inode->i_block[block] = ei->i_data[block];
4130
4131        raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
4132        if (ei->i_extra_isize) {
4133                if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
4134                        raw_inode->i_version_hi =
4135                        cpu_to_le32(inode->i_version >> 32);
4136                raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
4137        }
4138
4139        ext4_inode_csum_set(inode, raw_inode, ei);
4140
4141        BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
4142        rc = ext4_handle_dirty_metadata(handle, NULL, bh);
4143        if (!err)
4144                err = rc;
4145        ext4_clear_inode_state(inode, EXT4_STATE_NEW);
4146
4147        ext4_update_inode_fsync_trans(handle, inode, need_datasync);
4148out_brelse:
4149        brelse(bh);
4150        ext4_std_error(inode->i_sb, err);
4151        return err;
4152}
4153
4154/*
4155 * ext4_write_inode()
4156 *
4157 * We are called from a few places:
4158 *
4159 * - Within generic_file_write() for O_SYNC files.
4160 *   Here, there will be no transaction running. We wait for any running
4161 *   transaction to commit.
4162 *
4163 * - Within sys_sync(), kupdate and such.
4164 *   We wait on commit, if tol to.
4165 *
4166 * - Within prune_icache() (PF_MEMALLOC == true)
4167 *   Here we simply return.  We can't afford to block kswapd on the
4168 *   journal commit.
4169 *
4170 * In all cases it is actually safe for us to return without doing anything,
4171 * because the inode has been copied into a raw inode buffer in
4172 * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
4173 * knfsd.
4174 *
4175 * Note that we are absolutely dependent upon all inode dirtiers doing the
4176 * right thing: they *must* call mark_inode_dirty() after dirtying info in
4177 * which we are interested.
4178 *
4179 * It would be a bug for them to not do this.  The code:
4180 *
4181 *      mark_inode_dirty(inode)
4182 *      stuff();
4183 *      inode->i_size = expr;
4184 *
4185 * is in error because a kswapd-driven write_inode() could occur while
4186 * `stuff()' is running, and the new i_size will be lost.  Plus the inode
4187 * will no longer be on the superblock's dirty inode list.
4188 */
4189int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
4190{
4191        int err;
4192
4193        if (current->flags & PF_MEMALLOC)
4194                return 0;
4195
4196        if (EXT4_SB(inode->i_sb)->s_journal) {
4197                if (ext4_journal_current_handle()) {
4198                        jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
4199                        dump_stack();
4200                        return -EIO;
4201                }
4202
4203                if (wbc->sync_mode != WB_SYNC_ALL)
4204                        return 0;
4205
4206                err = ext4_force_commit(inode->i_sb);
4207        } else {
4208                struct ext4_iloc iloc;
4209
4210                err = __ext4_get_inode_loc(inode, &iloc, 0);
4211                if (err)
4212                        return err;
4213                if (wbc->sync_mode == WB_SYNC_ALL)
4214                        sync_dirty_buffer(iloc.bh);
4215                if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
4216                        EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
4217                                         "IO error syncing inode");
4218                        err = -EIO;
4219                }
4220                brelse(iloc.bh);
4221        }
4222        return err;
4223}
4224
4225/*
4226 * ext4_setattr()
4227 *
4228 * Called from notify_change.
4229 *
4230 * We want to trap VFS attempts to truncate the file as soon as
4231 * possible.  In particular, we want to make sure that when the VFS
4232 * shrinks i_size, we put the inode on the orphan list and modify
4233 * i_disksize immediately, so that during the subsequent flushing of
4234 * dirty pages and freeing of disk blocks, we can guarantee that any
4235 * commit will leave the blocks being flushed in an unused state on
4236 * disk.  (On recovery, the inode will get truncated and the blocks will
4237 * be freed, so we have a strong guarantee that no future commit will
4238 * leave these blocks visible to the user.)
4239 *
4240 * Another thing we have to assure is that if we are in ordered mode
4241 * and inode is still attached to the committing transaction, we must
4242 * we start writeout of all the dirty pages which are being truncated.
4243 * This way we are sure that all the data written in the previous
4244 * transaction are already on disk (truncate waits for pages under
4245 * writeback).
4246 *
4247 * Called with inode->i_mutex down.
4248 */
4249int ext4_setattr(struct dentry *dentry, struct iattr *attr)
4250{
4251        struct inode *inode = dentry->d_inode;
4252        int error, rc = 0;
4253        int orphan = 0;
4254        const unsigned int ia_valid = attr->ia_valid;
4255
4256        error = inode_change_ok(inode, attr);
4257        if (error)
4258                return error;
4259
4260        if (is_quota_modification(inode, attr))
4261                dquot_initialize(inode);
4262        if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, inode->i_uid)) ||
4263            (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, inode->i_gid))) {
4264                handle_t *handle;
4265
4266                /* (user+group)*(old+new) structure, inode write (sb,
4267                 * inode block, ? - but truncate inode update has it) */
4268                handle = ext4_journal_start(inode, (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)+
4269                                        EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb))+3);
4270                if (IS_ERR(handle)) {
4271                        error = PTR_ERR(handle);
4272                        goto err_out;
4273                }
4274                error = dquot_transfer(inode, attr);
4275                if (error) {
4276                        ext4_journal_stop(handle);
4277                        return error;
4278                }
4279                /* Update corresponding info in inode so that everything is in
4280                 * one transaction */
4281                if (attr->ia_valid & ATTR_UID)
4282                        inode->i_uid = attr->ia_uid;
4283                if (attr->ia_valid & ATTR_GID)
4284                        inode->i_gid = attr->ia_gid;
4285                error = ext4_mark_inode_dirty(handle, inode);
4286                ext4_journal_stop(handle);
4287        }
4288
4289        if (attr->ia_valid & ATTR_SIZE) {
4290
4291                if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
4292                        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
4293
4294                        if (attr->ia_size > sbi->s_bitmap_maxbytes)
4295                                return -EFBIG;
4296                }
4297        }
4298
4299        if (S_ISREG(inode->i_mode) &&
4300            attr->ia_valid & ATTR_SIZE &&
4301            (attr->ia_size < inode->i_size)) {
4302                handle_t *handle;
4303
4304                handle = ext4_journal_start(inode, 3);
4305                if (IS_ERR(handle)) {
4306                        error = PTR_ERR(handle);
4307                        goto err_out;
4308                }
4309                if (ext4_handle_valid(handle)) {
4310                        error = ext4_orphan_add(handle, inode);
4311                        orphan = 1;
4312                }
4313                EXT4_I(inode)->i_disksize = attr->ia_size;
4314                rc = ext4_mark_inode_dirty(handle, inode);
4315                if (!error)
4316                        error = rc;
4317                ext4_journal_stop(handle);
4318
4319                if (ext4_should_order_data(inode)) {
4320                        error = ext4_begin_ordered_truncate(inode,
4321                                                            attr->ia_size);
4322                        if (error) {
4323                                /* Do as much error cleanup as possible */
4324                                handle = ext4_journal_start(inode, 3);
4325                                if (IS_ERR(handle)) {
4326                                        ext4_orphan_del(NULL, inode);
4327                                        goto err_out;
4328                                }
4329                                ext4_orphan_del(handle, inode);
4330                                orphan = 0;
4331                                ext4_journal_stop(handle);
4332                                goto err_out;
4333                        }
4334                }
4335        }
4336
4337        if (attr->ia_valid & ATTR_SIZE) {
4338                if (attr->ia_size != i_size_read(inode)) {
4339                        truncate_setsize(inode, attr->ia_size);
4340                        /* Inode size will be reduced, wait for dio in flight.
4341                         * Temporarily disable dioread_nolock to prevent
4342                         * livelock. */
4343                        if (orphan) {
4344                                ext4_inode_block_unlocked_dio(inode);
4345                                inode_dio_wait(inode);
4346                                ext4_inode_resume_unlocked_dio(inode);
4347                        }
4348                }
4349                ext4_truncate(inode);
4350        }
4351
4352        if (!rc) {
4353                setattr_copy(inode, attr);
4354                mark_inode_dirty(inode);
4355        }
4356
4357        /*
4358         * If the call to ext4_truncate failed to get a transaction handle at
4359         * all, we need to clean up the in-core orphan list manually.
4360         */
4361        if (orphan && inode->i_nlink)
4362                ext4_orphan_del(NULL, inode);
4363
4364        if (!rc && (ia_valid & ATTR_MODE))
4365                rc = ext4_acl_chmod(inode);
4366
4367err_out:
4368        ext4_std_error(inode->i_sb, error);
4369        if (!error)
4370                error = rc;
4371        return error;
4372}
4373
4374int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
4375                 struct kstat *stat)
4376{
4377        struct inode *inode;
4378        unsigned long delalloc_blocks;
4379
4380        inode = dentry->d_inode;
4381        generic_fillattr(inode, stat);
4382
4383        /*
4384         * We can't update i_blocks if the block allocation is delayed
4385         * otherwise in the case of system crash before the real block
4386         * allocation is done, we will have i_blocks inconsistent with
4387         * on-disk file blocks.
4388         * We always keep i_blocks updated together with real
4389         * allocation. But to not confuse with user, stat
4390         * will return the blocks that include the delayed allocation
4391         * blocks for this file.
4392         */
4393        delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
4394                                EXT4_I(inode)->i_reserved_data_blocks);
4395
4396        stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9;
4397        return 0;
4398}
4399
4400static int ext4_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
4401{
4402        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
4403                return ext4_ind_trans_blocks(inode, nrblocks, chunk);
4404        return ext4_ext_index_trans_blocks(inode, nrblocks, chunk);
4405}
4406
4407/*
4408 * Account for index blocks, block groups bitmaps and block group
4409 * descriptor blocks if modify datablocks and index blocks
4410 * worse case, the indexs blocks spread over different block groups
4411 *
4412 * If datablocks are discontiguous, they are possible to spread over
4413 * different block groups too. If they are contiguous, with flexbg,
4414 * they could still across block group boundary.
4415 *
4416 * Also account for superblock, inode, quota and xattr blocks
4417 */
4418static int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
4419{
4420        ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
4421        int gdpblocks;
4422        int idxblocks;
4423        int ret = 0;
4424
4425        /*
4426         * How many index blocks need to touch to modify nrblocks?
4427         * The "Chunk" flag indicating whether the nrblocks is
4428         * physically contiguous on disk
4429         *
4430         * For Direct IO and fallocate, they calls get_block to allocate
4431         * one single extent at a time, so they could set the "Chunk" flag
4432         */
4433        idxblocks = ext4_index_trans_blocks(inode, nrblocks, chunk);
4434
4435        ret = idxblocks;
4436
4437        /*
4438         * Now let's see how many group bitmaps and group descriptors need
4439         * to account
4440         */
4441        groups = idxblocks;
4442        if (chunk)
4443                groups += 1;
4444        else
4445                groups += nrblocks;
4446
4447        gdpblocks = groups;
4448        if (groups > ngroups)
4449                groups = ngroups;
4450        if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
4451                gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
4452
4453        /* bitmaps and block group descriptor blocks */
4454        ret += groups + gdpblocks;
4455
4456        /* Blocks for super block, inode, quota and xattr blocks */
4457        ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
4458
4459        return ret;
4460}
4461
4462/*
4463 * Calculate the total number of credits to reserve to fit
4464 * the modification of a single pages into a single transaction,
4465 * which may include multiple chunks of block allocations.
4466 *
4467 * This could be called via ext4_write_begin()
4468 *
4469 * We need to consider the worse case, when
4470 * one new block per extent.
4471 */
4472int ext4_writepage_trans_blocks(struct inode *inode)
4473{
4474        int bpp = ext4_journal_blocks_per_page(inode);
4475        int ret;
4476
4477        ret = ext4_meta_trans_blocks(inode, bpp, 0);
4478
4479        /* Account for data blocks for journalled mode */
4480        if (ext4_should_journal_data(inode))
4481                ret += bpp;
4482        return ret;
4483}
4484
4485/*
4486 * Calculate the journal credits for a chunk of data modification.
4487 *
4488 * This is called from DIO, fallocate or whoever calling
4489 * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
4490 *
4491 * journal buffers for data blocks are not included here, as DIO
4492 * and fallocate do no need to journal data buffers.
4493 */
4494int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
4495{
4496        return ext4_meta_trans_blocks(inode, nrblocks, 1);
4497}
4498
4499/*
4500 * The caller must have previously called ext4_reserve_inode_write().
4501 * Give this, we know that the caller already has write access to iloc->bh.
4502 */
4503int ext4_mark_iloc_dirty(handle_t *handle,
4504                         struct inode *inode, struct ext4_iloc *iloc)
4505{
4506        int err = 0;
4507
4508        if (IS_I_VERSION(inode))
4509                inode_inc_iversion(inode);
4510
4511        /* the do_update_inode consumes one bh->b_count */
4512        get_bh(iloc->bh);
4513
4514        /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
4515        err = ext4_do_update_inode(handle, inode, iloc);
4516        put_bh(iloc->bh);
4517        return err;
4518}
4519
4520/*
4521 * On success, We end up with an outstanding reference count against
4522 * iloc->bh.  This _must_ be cleaned up later.
4523 */
4524
4525int
4526ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
4527                         struct ext4_iloc *iloc)
4528{
4529        int err;
4530
4531        err = ext4_get_inode_loc(inode, iloc);
4532        if (!err) {
4533                BUFFER_TRACE(iloc->bh, "get_write_access");
4534                err = ext4_journal_get_write_access(handle, iloc->bh);
4535                if (err) {
4536                        brelse(iloc->bh);
4537                        iloc->bh = NULL;
4538                }
4539        }
4540        ext4_std_error(inode->i_sb, err);
4541        return err;
4542}
4543
4544/*
4545 * Expand an inode by new_extra_isize bytes.
4546 * Returns 0 on success or negative error number on failure.
4547 */
4548static int ext4_expand_extra_isize(struct inode *inode,
4549                                   unsigned int new_extra_isize,
4550                                   struct ext4_iloc iloc,
4551                                   handle_t *handle)
4552{
4553        struct ext4_inode *raw_inode;
4554        struct ext4_xattr_ibody_header *header;
4555
4556        if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
4557                return 0;
4558
4559        raw_inode = ext4_raw_inode(&iloc);
4560
4561        header = IHDR(inode, raw_inode);
4562
4563        /* No extended attributes present */
4564        if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
4565            header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
4566                memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
4567                        new_extra_isize);
4568                EXT4_I(inode)->i_extra_isize = new_extra_isize;
4569                return 0;
4570        }
4571
4572        /* try to expand with EAs present */
4573        return ext4_expand_extra_isize_ea(inode, new_extra_isize,
4574                                          raw_inode, handle);
4575}
4576
4577/*
4578 * What we do here is to mark the in-core inode as clean with respect to inode
4579 * dirtiness (it may still be data-dirty).
4580 * This means that the in-core inode may be reaped by prune_icache
4581 * without having to perform any I/O.  This is a very good thing,
4582 * because *any* task may call prune_icache - even ones which
4583 * have a transaction open against a different journal.
4584 *
4585 * Is this cheating?  Not really.  Sure, we haven't written the
4586 * inode out, but prune_icache isn't a user-visible syncing function.
4587 * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
4588 * we start and wait on commits.
4589 */
4590int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
4591{
4592        struct ext4_iloc iloc;
4593        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
4594        static unsigned int mnt_count;
4595        int err, ret;
4596
4597        might_sleep();
4598        trace_ext4_mark_inode_dirty(inode, _RET_IP_);
4599        err = ext4_reserve_inode_write(handle, inode, &iloc);
4600        if (ext4_handle_valid(handle) &&
4601            EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
4602            !ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
4603                /*
4604                 * We need extra buffer credits since we may write into EA block
4605                 * with this same handle. If journal_extend fails, then it will
4606                 * only result in a minor loss of functionality for that inode.
4607                 * If this is felt to be critical, then e2fsck should be run to
4608                 * force a large enough s_min_extra_isize.
4609                 */
4610                if ((jbd2_journal_extend(handle,
4611                             EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) {
4612                        ret = ext4_expand_extra_isize(inode,
4613                                                      sbi->s_want_extra_isize,
4614                                                      iloc, handle);
4615                        if (ret) {
4616                                ext4_set_inode_state(inode,
4617                                                     EXT4_STATE_NO_EXPAND);
4618                                if (mnt_count !=
4619                                        le16_to_cpu(sbi->s_es->s_mnt_count)) {
4620                                        ext4_warning(inode->i_sb,
4621                                        "Unable to expand inode %lu. Delete"
4622                                        " some EAs or run e2fsck.",
4623                                        inode->i_ino);
4624                                        mnt_count =
4625                                          le16_to_cpu(sbi->s_es->s_mnt_count);
4626                                }
4627                        }
4628                }
4629        }
4630        if (!err)
4631                err = ext4_mark_iloc_dirty(handle, inode, &iloc);
4632        return err;
4633}
4634
4635/*
4636 * ext4_dirty_inode() is called from __mark_inode_dirty()
4637 *
4638 * We're really interested in the case where a file is being extended.
4639 * i_size has been changed by generic_commit_write() and we thus need
4640 * to include the updated inode in the current transaction.
4641 *
4642 * Also, dquot_alloc_block() will always dirty the inode when blocks
4643 * are allocated to the file.
4644 *
4645 * If the inode is marked synchronous, we don't honour that here - doing
4646 * so would cause a commit on atime updates, which we don't bother doing.
4647 * We handle synchronous inodes at the highest possible level.
4648 */
4649void ext4_dirty_inode(struct inode *inode, int flags)
4650{
4651        handle_t *handle;
4652
4653        handle = ext4_journal_start(inode, 2);
4654        if (IS_ERR(handle))
4655                goto out;
4656
4657        ext4_mark_inode_dirty(handle, inode);
4658
4659        ext4_journal_stop(handle);
4660out:
4661        return;
4662}
4663
4664#if 0
4665/*
4666 * Bind an inode's backing buffer_head into this transaction, to prevent
4667 * it from being flushed to disk early.  Unlike
4668 * ext4_reserve_inode_write, this leaves behind no bh reference and
4669 * returns no iloc structure, so the caller needs to repeat the iloc
4670 * lookup to mark the inode dirty later.
4671 */
4672static int ext4_pin_inode(handle_t *handle, struct inode *inode)
4673{
4674        struct ext4_iloc iloc;
4675
4676        int err = 0;
4677        if (handle) {
4678                err = ext4_get_inode_loc(inode, &iloc);
4679                if (!err) {
4680                        BUFFER_TRACE(iloc.bh, "get_write_access");
4681                        err = jbd2_journal_get_write_access(handle, iloc.bh);
4682                        if (!err)
4683                                err = ext4_handle_dirty_metadata(handle,
4684                                                                 NULL,
4685                                                                 iloc.bh);
4686                        brelse(iloc.bh);
4687                }
4688        }
4689        ext4_std_error(inode->i_sb, err);
4690        return err;
4691}
4692#endif
4693
4694int ext4_change_inode_journal_flag(struct inode *inode, int val)
4695{
4696        journal_t *journal;
4697        handle_t *handle;
4698        int err;
4699
4700        /*
4701         * We have to be very careful here: changing a data block's
4702         * journaling status dynamically is dangerous.  If we write a
4703         * data block to the journal, change the status and then delete
4704         * that block, we risk forgetting to revoke the old log record
4705         * from the journal and so a subsequent replay can corrupt data.
4706         * So, first we make sure that the journal is empty and that
4707         * nobody is changing anything.
4708         */
4709
4710        journal = EXT4_JOURNAL(inode);
4711        if (!journal)
4712                return 0;
4713        if (is_journal_aborted(journal))
4714                return -EROFS;
4715        /* We have to allocate physical blocks for delalloc blocks
4716         * before flushing journal. otherwise delalloc blocks can not
4717         * be allocated any more. even more truncate on delalloc blocks
4718         * could trigger BUG by flushing delalloc blocks in journal.
4719         * There is no delalloc block in non-journal data mode.
4720         */
4721        if (val && test_opt(inode->i_sb, DELALLOC)) {
4722                err = ext4_alloc_da_blocks(inode);
4723                if (err < 0)
4724                        return err;
4725        }
4726
4727        /* Wait for all existing dio workers */
4728        ext4_inode_block_unlocked_dio(inode);
4729        inode_dio_wait(inode);
4730
4731        jbd2_journal_lock_updates(journal);
4732
4733        /*
4734         * OK, there are no updates running now, and all cached data is
4735         * synced to disk.  We are now in a completely consistent state
4736         * which doesn't have anything in the journal, and we know that
4737         * no filesystem updates are running, so it is safe to modify
4738         * the inode's in-core data-journaling state flag now.
4739         */
4740
4741        if (val)
4742                ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
4743        else {
4744                jbd2_journal_flush(journal);
4745                ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
4746        }
4747        ext4_set_aops(inode);
4748
4749        jbd2_journal_unlock_updates(journal);
4750        ext4_inode_resume_unlocked_dio(inode);
4751
4752        /* Finally we can mark the inode as dirty. */
4753
4754        handle = ext4_journal_start(inode, 1);
4755        if (IS_ERR(handle))
4756                return PTR_ERR(handle);
4757
4758        err = ext4_mark_inode_dirty(handle, inode);
4759        ext4_handle_sync(handle);
4760        ext4_journal_stop(handle);
4761        ext4_std_error(inode->i_sb, err);
4762
4763        return err;
4764}
4765
4766static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
4767{
4768        return !buffer_mapped(bh);
4769}
4770
4771int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
4772{
4773        struct page *page = vmf->page;
4774        loff_t size;
4775        unsigned long len;
4776        int ret;
4777        struct file *file = vma->vm_file;
4778        struct inode *inode = file->f_path.dentry->d_inode;
4779        struct address_space *mapping = inode->i_mapping;
4780        handle_t *handle;
4781        get_block_t *get_block;
4782        int retries = 0;
4783
4784        sb_start_pagefault(inode->i_sb);
4785        file_update_time(vma->vm_file);
4786        /* Delalloc case is easy... */
4787        if (test_opt(inode->i_sb, DELALLOC) &&
4788            !ext4_should_journal_data(inode) &&
4789            !ext4_nonda_switch(inode->i_sb)) {
4790                do {
4791                        ret = __block_page_mkwrite(vma, vmf,
4792                                                   ext4_da_get_block_prep);
4793                } while (ret == -ENOSPC &&
4794                       ext4_should_retry_alloc(inode->i_sb, &retries));
4795                goto out_ret;
4796        }
4797
4798        lock_page(page);
4799        size = i_size_read(inode);
4800        /* Page got truncated from under us? */
4801        if (page->mapping != mapping || page_offset(page) > size) {
4802                unlock_page(page);
4803                ret = VM_FAULT_NOPAGE;
4804                goto out;
4805        }
4806
4807        if (page->index == size >> PAGE_CACHE_SHIFT)
4808                len = size & ~PAGE_CACHE_MASK;
4809        else
4810                len = PAGE_CACHE_SIZE;
4811        /*
4812         * Return if we have all the buffers mapped. This avoids the need to do
4813         * journal_start/journal_stop which can block and take a long time
4814         */
4815        if (page_has_buffers(page)) {
4816                if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
4817                                        ext4_bh_unmapped)) {
4818                        /* Wait so that we don't change page under IO */
4819                        wait_on_page_writeback(page);
4820                        ret = VM_FAULT_LOCKED;
4821                        goto out;
4822                }
4823        }
4824        unlock_page(page);
4825        /* OK, we need to fill the hole... */
4826        if (ext4_should_dioread_nolock(inode))
4827                get_block = ext4_get_block_write;
4828        else
4829                get_block = ext4_get_block;
4830retry_alloc:
4831        handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
4832        if (IS_ERR(handle)) {
4833                ret = VM_FAULT_SIGBUS;
4834                goto out;
4835        }
4836        ret = __block_page_mkwrite(vma, vmf, get_block);
4837        if (!ret && ext4_should_journal_data(inode)) {
4838                if (walk_page_buffers(handle, page_buffers(page), 0,
4839                          PAGE_CACHE_SIZE, NULL, do_journal_get_write_access)) {
4840                        unlock_page(page);
4841                        ret = VM_FAULT_SIGBUS;
4842                        ext4_journal_stop(handle);
4843                        goto out;
4844                }
4845                ext4_set_inode_state(inode, EXT4_STATE_JDATA);
4846        }
4847        ext4_journal_stop(handle);
4848        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
4849                goto retry_alloc;
4850out_ret:
4851        ret = block_page_mkwrite_return(ret);
4852out:
4853        sb_end_pagefault(inode->i_sb);
4854        return ret;
4855}
4856
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