linux/fs/btrfs/file.c
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   1/*
   2 * Copyright (C) 2007 Oracle.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/fs.h>
  20#include <linux/pagemap.h>
  21#include <linux/highmem.h>
  22#include <linux/time.h>
  23#include <linux/init.h>
  24#include <linux/string.h>
  25#include <linux/backing-dev.h>
  26#include <linux/mpage.h>
  27#include <linux/falloc.h>
  28#include <linux/swap.h>
  29#include <linux/writeback.h>
  30#include <linux/statfs.h>
  31#include <linux/compat.h>
  32#include <linux/slab.h>
  33#include "ctree.h"
  34#include "disk-io.h"
  35#include "transaction.h"
  36#include "btrfs_inode.h"
  37#include "ioctl.h"
  38#include "print-tree.h"
  39#include "tree-log.h"
  40#include "locking.h"
  41#include "compat.h"
  42
  43/*
  44 * when auto defrag is enabled we
  45 * queue up these defrag structs to remember which
  46 * inodes need defragging passes
  47 */
  48struct inode_defrag {
  49        struct rb_node rb_node;
  50        /* objectid */
  51        u64 ino;
  52        /*
  53         * transid where the defrag was added, we search for
  54         * extents newer than this
  55         */
  56        u64 transid;
  57
  58        /* root objectid */
  59        u64 root;
  60
  61        /* last offset we were able to defrag */
  62        u64 last_offset;
  63
  64        /* if we've wrapped around back to zero once already */
  65        int cycled;
  66};
  67
  68static int __compare_inode_defrag(struct inode_defrag *defrag1,
  69                                  struct inode_defrag *defrag2)
  70{
  71        if (defrag1->root > defrag2->root)
  72                return 1;
  73        else if (defrag1->root < defrag2->root)
  74                return -1;
  75        else if (defrag1->ino > defrag2->ino)
  76                return 1;
  77        else if (defrag1->ino < defrag2->ino)
  78                return -1;
  79        else
  80                return 0;
  81}
  82
  83/* pop a record for an inode into the defrag tree.  The lock
  84 * must be held already
  85 *
  86 * If you're inserting a record for an older transid than an
  87 * existing record, the transid already in the tree is lowered
  88 *
  89 * If an existing record is found the defrag item you
  90 * pass in is freed
  91 */
  92static void __btrfs_add_inode_defrag(struct inode *inode,
  93                                    struct inode_defrag *defrag)
  94{
  95        struct btrfs_root *root = BTRFS_I(inode)->root;
  96        struct inode_defrag *entry;
  97        struct rb_node **p;
  98        struct rb_node *parent = NULL;
  99        int ret;
 100
 101        p = &root->fs_info->defrag_inodes.rb_node;
 102        while (*p) {
 103                parent = *p;
 104                entry = rb_entry(parent, struct inode_defrag, rb_node);
 105
 106                ret = __compare_inode_defrag(defrag, entry);
 107                if (ret < 0)
 108                        p = &parent->rb_left;
 109                else if (ret > 0)
 110                        p = &parent->rb_right;
 111                else {
 112                        /* if we're reinserting an entry for
 113                         * an old defrag run, make sure to
 114                         * lower the transid of our existing record
 115                         */
 116                        if (defrag->transid < entry->transid)
 117                                entry->transid = defrag->transid;
 118                        if (defrag->last_offset > entry->last_offset)
 119                                entry->last_offset = defrag->last_offset;
 120                        goto exists;
 121                }
 122        }
 123        set_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
 124        rb_link_node(&defrag->rb_node, parent, p);
 125        rb_insert_color(&defrag->rb_node, &root->fs_info->defrag_inodes);
 126        return;
 127
 128exists:
 129        kfree(defrag);
 130        return;
 131
 132}
 133
 134/*
 135 * insert a defrag record for this inode if auto defrag is
 136 * enabled
 137 */
 138int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
 139                           struct inode *inode)
 140{
 141        struct btrfs_root *root = BTRFS_I(inode)->root;
 142        struct inode_defrag *defrag;
 143        u64 transid;
 144
 145        if (!btrfs_test_opt(root, AUTO_DEFRAG))
 146                return 0;
 147
 148        if (btrfs_fs_closing(root->fs_info))
 149                return 0;
 150
 151        if (test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags))
 152                return 0;
 153
 154        if (trans)
 155                transid = trans->transid;
 156        else
 157                transid = BTRFS_I(inode)->root->last_trans;
 158
 159        defrag = kzalloc(sizeof(*defrag), GFP_NOFS);
 160        if (!defrag)
 161                return -ENOMEM;
 162
 163        defrag->ino = btrfs_ino(inode);
 164        defrag->transid = transid;
 165        defrag->root = root->root_key.objectid;
 166
 167        spin_lock(&root->fs_info->defrag_inodes_lock);
 168        if (!test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags))
 169                __btrfs_add_inode_defrag(inode, defrag);
 170        else
 171                kfree(defrag);
 172        spin_unlock(&root->fs_info->defrag_inodes_lock);
 173        return 0;
 174}
 175
 176/*
 177 * must be called with the defrag_inodes lock held
 178 */
 179struct inode_defrag *btrfs_find_defrag_inode(struct btrfs_fs_info *info,
 180                                             u64 root, u64 ino,
 181                                             struct rb_node **next)
 182{
 183        struct inode_defrag *entry = NULL;
 184        struct inode_defrag tmp;
 185        struct rb_node *p;
 186        struct rb_node *parent = NULL;
 187        int ret;
 188
 189        tmp.ino = ino;
 190        tmp.root = root;
 191
 192        p = info->defrag_inodes.rb_node;
 193        while (p) {
 194                parent = p;
 195                entry = rb_entry(parent, struct inode_defrag, rb_node);
 196
 197                ret = __compare_inode_defrag(&tmp, entry);
 198                if (ret < 0)
 199                        p = parent->rb_left;
 200                else if (ret > 0)
 201                        p = parent->rb_right;
 202                else
 203                        return entry;
 204        }
 205
 206        if (next) {
 207                while (parent && __compare_inode_defrag(&tmp, entry) > 0) {
 208                        parent = rb_next(parent);
 209                        entry = rb_entry(parent, struct inode_defrag, rb_node);
 210                }
 211                *next = parent;
 212        }
 213        return NULL;
 214}
 215
 216/*
 217 * run through the list of inodes in the FS that need
 218 * defragging
 219 */
 220int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
 221{
 222        struct inode_defrag *defrag;
 223        struct btrfs_root *inode_root;
 224        struct inode *inode;
 225        struct rb_node *n;
 226        struct btrfs_key key;
 227        struct btrfs_ioctl_defrag_range_args range;
 228        u64 first_ino = 0;
 229        u64 root_objectid = 0;
 230        int num_defrag;
 231        int defrag_batch = 1024;
 232
 233        memset(&range, 0, sizeof(range));
 234        range.len = (u64)-1;
 235
 236        atomic_inc(&fs_info->defrag_running);
 237        spin_lock(&fs_info->defrag_inodes_lock);
 238        while(1) {
 239                n = NULL;
 240
 241                /* find an inode to defrag */
 242                defrag = btrfs_find_defrag_inode(fs_info, root_objectid,
 243                                                 first_ino, &n);
 244                if (!defrag) {
 245                        if (n) {
 246                                defrag = rb_entry(n, struct inode_defrag,
 247                                                  rb_node);
 248                        } else if (root_objectid || first_ino) {
 249                                root_objectid = 0;
 250                                first_ino = 0;
 251                                continue;
 252                        } else {
 253                                break;
 254                        }
 255                }
 256
 257                /* remove it from the rbtree */
 258                first_ino = defrag->ino + 1;
 259                root_objectid = defrag->root;
 260                rb_erase(&defrag->rb_node, &fs_info->defrag_inodes);
 261
 262                if (btrfs_fs_closing(fs_info))
 263                        goto next_free;
 264
 265                spin_unlock(&fs_info->defrag_inodes_lock);
 266
 267                /* get the inode */
 268                key.objectid = defrag->root;
 269                btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 270                key.offset = (u64)-1;
 271                inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
 272                if (IS_ERR(inode_root))
 273                        goto next;
 274
 275                key.objectid = defrag->ino;
 276                btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 277                key.offset = 0;
 278
 279                inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
 280                if (IS_ERR(inode))
 281                        goto next;
 282
 283                /* do a chunk of defrag */
 284                clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
 285                range.start = defrag->last_offset;
 286                num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
 287                                               defrag_batch);
 288                /*
 289                 * if we filled the whole defrag batch, there
 290                 * must be more work to do.  Queue this defrag
 291                 * again
 292                 */
 293                if (num_defrag == defrag_batch) {
 294                        defrag->last_offset = range.start;
 295                        __btrfs_add_inode_defrag(inode, defrag);
 296                        /*
 297                         * we don't want to kfree defrag, we added it back to
 298                         * the rbtree
 299                         */
 300                        defrag = NULL;
 301                } else if (defrag->last_offset && !defrag->cycled) {
 302                        /*
 303                         * we didn't fill our defrag batch, but
 304                         * we didn't start at zero.  Make sure we loop
 305                         * around to the start of the file.
 306                         */
 307                        defrag->last_offset = 0;
 308                        defrag->cycled = 1;
 309                        __btrfs_add_inode_defrag(inode, defrag);
 310                        defrag = NULL;
 311                }
 312
 313                iput(inode);
 314next:
 315                spin_lock(&fs_info->defrag_inodes_lock);
 316next_free:
 317                kfree(defrag);
 318        }
 319        spin_unlock(&fs_info->defrag_inodes_lock);
 320
 321        atomic_dec(&fs_info->defrag_running);
 322
 323        /*
 324         * during unmount, we use the transaction_wait queue to
 325         * wait for the defragger to stop
 326         */
 327        wake_up(&fs_info->transaction_wait);
 328        return 0;
 329}
 330
 331/* simple helper to fault in pages and copy.  This should go away
 332 * and be replaced with calls into generic code.
 333 */
 334static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
 335                                         size_t write_bytes,
 336                                         struct page **prepared_pages,
 337                                         struct iov_iter *i)
 338{
 339        size_t copied = 0;
 340        size_t total_copied = 0;
 341        int pg = 0;
 342        int offset = pos & (PAGE_CACHE_SIZE - 1);
 343
 344        while (write_bytes > 0) {
 345                size_t count = min_t(size_t,
 346                                     PAGE_CACHE_SIZE - offset, write_bytes);
 347                struct page *page = prepared_pages[pg];
 348                /*
 349                 * Copy data from userspace to the current page
 350                 *
 351                 * Disable pagefault to avoid recursive lock since
 352                 * the pages are already locked
 353                 */
 354                pagefault_disable();
 355                copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
 356                pagefault_enable();
 357
 358                /* Flush processor's dcache for this page */
 359                flush_dcache_page(page);
 360
 361                /*
 362                 * if we get a partial write, we can end up with
 363                 * partially up to date pages.  These add
 364                 * a lot of complexity, so make sure they don't
 365                 * happen by forcing this copy to be retried.
 366                 *
 367                 * The rest of the btrfs_file_write code will fall
 368                 * back to page at a time copies after we return 0.
 369                 */
 370                if (!PageUptodate(page) && copied < count)
 371                        copied = 0;
 372
 373                iov_iter_advance(i, copied);
 374                write_bytes -= copied;
 375                total_copied += copied;
 376
 377                /* Return to btrfs_file_aio_write to fault page */
 378                if (unlikely(copied == 0))
 379                        break;
 380
 381                if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
 382                        offset += copied;
 383                } else {
 384                        pg++;
 385                        offset = 0;
 386                }
 387        }
 388        return total_copied;
 389}
 390
 391/*
 392 * unlocks pages after btrfs_file_write is done with them
 393 */
 394void btrfs_drop_pages(struct page **pages, size_t num_pages)
 395{
 396        size_t i;
 397        for (i = 0; i < num_pages; i++) {
 398                /* page checked is some magic around finding pages that
 399                 * have been modified without going through btrfs_set_page_dirty
 400                 * clear it here
 401                 */
 402                ClearPageChecked(pages[i]);
 403                unlock_page(pages[i]);
 404                mark_page_accessed(pages[i]);
 405                page_cache_release(pages[i]);
 406        }
 407}
 408
 409/*
 410 * after copy_from_user, pages need to be dirtied and we need to make
 411 * sure holes are created between the current EOF and the start of
 412 * any next extents (if required).
 413 *
 414 * this also makes the decision about creating an inline extent vs
 415 * doing real data extents, marking pages dirty and delalloc as required.
 416 */
 417int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
 418                      struct page **pages, size_t num_pages,
 419                      loff_t pos, size_t write_bytes,
 420                      struct extent_state **cached)
 421{
 422        int err = 0;
 423        int i;
 424        u64 num_bytes;
 425        u64 start_pos;
 426        u64 end_of_last_block;
 427        u64 end_pos = pos + write_bytes;
 428        loff_t isize = i_size_read(inode);
 429
 430        start_pos = pos & ~((u64)root->sectorsize - 1);
 431        num_bytes = (write_bytes + pos - start_pos +
 432                    root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 433
 434        end_of_last_block = start_pos + num_bytes - 1;
 435        err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 436                                        cached);
 437        if (err)
 438                return err;
 439
 440        for (i = 0; i < num_pages; i++) {
 441                struct page *p = pages[i];
 442                SetPageUptodate(p);
 443                ClearPageChecked(p);
 444                set_page_dirty(p);
 445        }
 446
 447        /*
 448         * we've only changed i_size in ram, and we haven't updated
 449         * the disk i_size.  There is no need to log the inode
 450         * at this time.
 451         */
 452        if (end_pos > isize)
 453                i_size_write(inode, end_pos);
 454        return 0;
 455}
 456
 457/*
 458 * this drops all the extents in the cache that intersect the range
 459 * [start, end].  Existing extents are split as required.
 460 */
 461int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 462                            int skip_pinned)
 463{
 464        struct extent_map *em;
 465        struct extent_map *split = NULL;
 466        struct extent_map *split2 = NULL;
 467        struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 468        u64 len = end - start + 1;
 469        int ret;
 470        int testend = 1;
 471        unsigned long flags;
 472        int compressed = 0;
 473
 474        WARN_ON(end < start);
 475        if (end == (u64)-1) {
 476                len = (u64)-1;
 477                testend = 0;
 478        }
 479        while (1) {
 480                if (!split)
 481                        split = alloc_extent_map();
 482                if (!split2)
 483                        split2 = alloc_extent_map();
 484                BUG_ON(!split || !split2); /* -ENOMEM */
 485
 486                write_lock(&em_tree->lock);
 487                em = lookup_extent_mapping(em_tree, start, len);
 488                if (!em) {
 489                        write_unlock(&em_tree->lock);
 490                        break;
 491                }
 492                flags = em->flags;
 493                if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
 494                        if (testend && em->start + em->len >= start + len) {
 495                                free_extent_map(em);
 496                                write_unlock(&em_tree->lock);
 497                                break;
 498                        }
 499                        start = em->start + em->len;
 500                        if (testend)
 501                                len = start + len - (em->start + em->len);
 502                        free_extent_map(em);
 503                        write_unlock(&em_tree->lock);
 504                        continue;
 505                }
 506                compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
 507                clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 508                remove_extent_mapping(em_tree, em);
 509
 510                if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 511                    em->start < start) {
 512                        split->start = em->start;
 513                        split->len = start - em->start;
 514                        split->orig_start = em->orig_start;
 515                        split->block_start = em->block_start;
 516
 517                        if (compressed)
 518                                split->block_len = em->block_len;
 519                        else
 520                                split->block_len = split->len;
 521
 522                        split->bdev = em->bdev;
 523                        split->flags = flags;
 524                        split->compress_type = em->compress_type;
 525                        ret = add_extent_mapping(em_tree, split);
 526                        BUG_ON(ret); /* Logic error */
 527                        free_extent_map(split);
 528                        split = split2;
 529                        split2 = NULL;
 530                }
 531                if (em->block_start < EXTENT_MAP_LAST_BYTE &&
 532                    testend && em->start + em->len > start + len) {
 533                        u64 diff = start + len - em->start;
 534
 535                        split->start = start + len;
 536                        split->len = em->start + em->len - (start + len);
 537                        split->bdev = em->bdev;
 538                        split->flags = flags;
 539                        split->compress_type = em->compress_type;
 540
 541                        if (compressed) {
 542                                split->block_len = em->block_len;
 543                                split->block_start = em->block_start;
 544                                split->orig_start = em->orig_start;
 545                        } else {
 546                                split->block_len = split->len;
 547                                split->block_start = em->block_start + diff;
 548                                split->orig_start = split->start;
 549                        }
 550
 551                        ret = add_extent_mapping(em_tree, split);
 552                        BUG_ON(ret); /* Logic error */
 553                        free_extent_map(split);
 554                        split = NULL;
 555                }
 556                write_unlock(&em_tree->lock);
 557
 558                /* once for us */
 559                free_extent_map(em);
 560                /* once for the tree*/
 561                free_extent_map(em);
 562        }
 563        if (split)
 564                free_extent_map(split);
 565        if (split2)
 566                free_extent_map(split2);
 567        return 0;
 568}
 569
 570/*
 571 * this is very complex, but the basic idea is to drop all extents
 572 * in the range start - end.  hint_block is filled in with a block number
 573 * that would be a good hint to the block allocator for this file.
 574 *
 575 * If an extent intersects the range but is not entirely inside the range
 576 * it is either truncated or split.  Anything entirely inside the range
 577 * is deleted from the tree.
 578 */
 579int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 580                       u64 start, u64 end, u64 *hint_byte, int drop_cache)
 581{
 582        struct btrfs_root *root = BTRFS_I(inode)->root;
 583        struct extent_buffer *leaf;
 584        struct btrfs_file_extent_item *fi;
 585        struct btrfs_path *path;
 586        struct btrfs_key key;
 587        struct btrfs_key new_key;
 588        u64 ino = btrfs_ino(inode);
 589        u64 search_start = start;
 590        u64 disk_bytenr = 0;
 591        u64 num_bytes = 0;
 592        u64 extent_offset = 0;
 593        u64 extent_end = 0;
 594        int del_nr = 0;
 595        int del_slot = 0;
 596        int extent_type;
 597        int recow;
 598        int ret;
 599        int modify_tree = -1;
 600
 601        if (drop_cache)
 602                btrfs_drop_extent_cache(inode, start, end - 1, 0);
 603
 604        path = btrfs_alloc_path();
 605        if (!path)
 606                return -ENOMEM;
 607
 608        if (start >= BTRFS_I(inode)->disk_i_size)
 609                modify_tree = 0;
 610
 611        while (1) {
 612                recow = 0;
 613                ret = btrfs_lookup_file_extent(trans, root, path, ino,
 614                                               search_start, modify_tree);
 615                if (ret < 0)
 616                        break;
 617                if (ret > 0 && path->slots[0] > 0 && search_start == start) {
 618                        leaf = path->nodes[0];
 619                        btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 620                        if (key.objectid == ino &&
 621                            key.type == BTRFS_EXTENT_DATA_KEY)
 622                                path->slots[0]--;
 623                }
 624                ret = 0;
 625next_slot:
 626                leaf = path->nodes[0];
 627                if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 628                        BUG_ON(del_nr > 0);
 629                        ret = btrfs_next_leaf(root, path);
 630                        if (ret < 0)
 631                                break;
 632                        if (ret > 0) {
 633                                ret = 0;
 634                                break;
 635                        }
 636                        leaf = path->nodes[0];
 637                        recow = 1;
 638                }
 639
 640                btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 641                if (key.objectid > ino ||
 642                    key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
 643                        break;
 644
 645                fi = btrfs_item_ptr(leaf, path->slots[0],
 646                                    struct btrfs_file_extent_item);
 647                extent_type = btrfs_file_extent_type(leaf, fi);
 648
 649                if (extent_type == BTRFS_FILE_EXTENT_REG ||
 650                    extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 651                        disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 652                        num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 653                        extent_offset = btrfs_file_extent_offset(leaf, fi);
 654                        extent_end = key.offset +
 655                                btrfs_file_extent_num_bytes(leaf, fi);
 656                } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 657                        extent_end = key.offset +
 658                                btrfs_file_extent_inline_len(leaf, fi);
 659                } else {
 660                        WARN_ON(1);
 661                        extent_end = search_start;
 662                }
 663
 664                if (extent_end <= search_start) {
 665                        path->slots[0]++;
 666                        goto next_slot;
 667                }
 668
 669                search_start = max(key.offset, start);
 670                if (recow || !modify_tree) {
 671                        modify_tree = -1;
 672                        btrfs_release_path(path);
 673                        continue;
 674                }
 675
 676                /*
 677                 *     | - range to drop - |
 678                 *  | -------- extent -------- |
 679                 */
 680                if (start > key.offset && end < extent_end) {
 681                        BUG_ON(del_nr > 0);
 682                        BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 683
 684                        memcpy(&new_key, &key, sizeof(new_key));
 685                        new_key.offset = start;
 686                        ret = btrfs_duplicate_item(trans, root, path,
 687                                                   &new_key);
 688                        if (ret == -EAGAIN) {
 689                                btrfs_release_path(path);
 690                                continue;
 691                        }
 692                        if (ret < 0)
 693                                break;
 694
 695                        leaf = path->nodes[0];
 696                        fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 697                                            struct btrfs_file_extent_item);
 698                        btrfs_set_file_extent_num_bytes(leaf, fi,
 699                                                        start - key.offset);
 700
 701                        fi = btrfs_item_ptr(leaf, path->slots[0],
 702                                            struct btrfs_file_extent_item);
 703
 704                        extent_offset += start - key.offset;
 705                        btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 706                        btrfs_set_file_extent_num_bytes(leaf, fi,
 707                                                        extent_end - start);
 708                        btrfs_mark_buffer_dirty(leaf);
 709
 710                        if (disk_bytenr > 0) {
 711                                ret = btrfs_inc_extent_ref(trans, root,
 712                                                disk_bytenr, num_bytes, 0,
 713                                                root->root_key.objectid,
 714                                                new_key.objectid,
 715                                                start - extent_offset, 0);
 716                                BUG_ON(ret); /* -ENOMEM */
 717                                *hint_byte = disk_bytenr;
 718                        }
 719                        key.offset = start;
 720                }
 721                /*
 722                 *  | ---- range to drop ----- |
 723                 *      | -------- extent -------- |
 724                 */
 725                if (start <= key.offset && end < extent_end) {
 726                        BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 727
 728                        memcpy(&new_key, &key, sizeof(new_key));
 729                        new_key.offset = end;
 730                        btrfs_set_item_key_safe(trans, root, path, &new_key);
 731
 732                        extent_offset += end - key.offset;
 733                        btrfs_set_file_extent_offset(leaf, fi, extent_offset);
 734                        btrfs_set_file_extent_num_bytes(leaf, fi,
 735                                                        extent_end - end);
 736                        btrfs_mark_buffer_dirty(leaf);
 737                        if (disk_bytenr > 0) {
 738                                inode_sub_bytes(inode, end - key.offset);
 739                                *hint_byte = disk_bytenr;
 740                        }
 741                        break;
 742                }
 743
 744                search_start = extent_end;
 745                /*
 746                 *       | ---- range to drop ----- |
 747                 *  | -------- extent -------- |
 748                 */
 749                if (start > key.offset && end >= extent_end) {
 750                        BUG_ON(del_nr > 0);
 751                        BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
 752
 753                        btrfs_set_file_extent_num_bytes(leaf, fi,
 754                                                        start - key.offset);
 755                        btrfs_mark_buffer_dirty(leaf);
 756                        if (disk_bytenr > 0) {
 757                                inode_sub_bytes(inode, extent_end - start);
 758                                *hint_byte = disk_bytenr;
 759                        }
 760                        if (end == extent_end)
 761                                break;
 762
 763                        path->slots[0]++;
 764                        goto next_slot;
 765                }
 766
 767                /*
 768                 *  | ---- range to drop ----- |
 769                 *    | ------ extent ------ |
 770                 */
 771                if (start <= key.offset && end >= extent_end) {
 772                        if (del_nr == 0) {
 773                                del_slot = path->slots[0];
 774                                del_nr = 1;
 775                        } else {
 776                                BUG_ON(del_slot + del_nr != path->slots[0]);
 777                                del_nr++;
 778                        }
 779
 780                        if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 781                                inode_sub_bytes(inode,
 782                                                extent_end - key.offset);
 783                                extent_end = ALIGN(extent_end,
 784                                                   root->sectorsize);
 785                        } else if (disk_bytenr > 0) {
 786                                ret = btrfs_free_extent(trans, root,
 787                                                disk_bytenr, num_bytes, 0,
 788                                                root->root_key.objectid,
 789                                                key.objectid, key.offset -
 790                                                extent_offset, 0);
 791                                BUG_ON(ret); /* -ENOMEM */
 792                                inode_sub_bytes(inode,
 793                                                extent_end - key.offset);
 794                                *hint_byte = disk_bytenr;
 795                        }
 796
 797                        if (end == extent_end)
 798                                break;
 799
 800                        if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
 801                                path->slots[0]++;
 802                                goto next_slot;
 803                        }
 804
 805                        ret = btrfs_del_items(trans, root, path, del_slot,
 806                                              del_nr);
 807                        if (ret) {
 808                                btrfs_abort_transaction(trans, root, ret);
 809                                goto out;
 810                        }
 811
 812                        del_nr = 0;
 813                        del_slot = 0;
 814
 815                        btrfs_release_path(path);
 816                        continue;
 817                }
 818
 819                BUG_ON(1);
 820        }
 821
 822        if (!ret && del_nr > 0) {
 823                ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
 824                if (ret)
 825                        btrfs_abort_transaction(trans, root, ret);
 826        }
 827
 828out:
 829        btrfs_free_path(path);
 830        return ret;
 831}
 832
 833static int extent_mergeable(struct extent_buffer *leaf, int slot,
 834                            u64 objectid, u64 bytenr, u64 orig_offset,
 835                            u64 *start, u64 *end)
 836{
 837        struct btrfs_file_extent_item *fi;
 838        struct btrfs_key key;
 839        u64 extent_end;
 840
 841        if (slot < 0 || slot >= btrfs_header_nritems(leaf))
 842                return 0;
 843
 844        btrfs_item_key_to_cpu(leaf, &key, slot);
 845        if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
 846                return 0;
 847
 848        fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 849        if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
 850            btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
 851            btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
 852            btrfs_file_extent_compression(leaf, fi) ||
 853            btrfs_file_extent_encryption(leaf, fi) ||
 854            btrfs_file_extent_other_encoding(leaf, fi))
 855                return 0;
 856
 857        extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 858        if ((*start && *start != key.offset) || (*end && *end != extent_end))
 859                return 0;
 860
 861        *start = key.offset;
 862        *end = extent_end;
 863        return 1;
 864}
 865
 866/*
 867 * Mark extent in the range start - end as written.
 868 *
 869 * This changes extent type from 'pre-allocated' to 'regular'. If only
 870 * part of extent is marked as written, the extent will be split into
 871 * two or three.
 872 */
 873int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 874                              struct inode *inode, u64 start, u64 end)
 875{
 876        struct btrfs_root *root = BTRFS_I(inode)->root;
 877        struct extent_buffer *leaf;
 878        struct btrfs_path *path;
 879        struct btrfs_file_extent_item *fi;
 880        struct btrfs_key key;
 881        struct btrfs_key new_key;
 882        u64 bytenr;
 883        u64 num_bytes;
 884        u64 extent_end;
 885        u64 orig_offset;
 886        u64 other_start;
 887        u64 other_end;
 888        u64 split;
 889        int del_nr = 0;
 890        int del_slot = 0;
 891        int recow;
 892        int ret;
 893        u64 ino = btrfs_ino(inode);
 894
 895        btrfs_drop_extent_cache(inode, start, end - 1, 0);
 896
 897        path = btrfs_alloc_path();
 898        if (!path)
 899                return -ENOMEM;
 900again:
 901        recow = 0;
 902        split = start;
 903        key.objectid = ino;
 904        key.type = BTRFS_EXTENT_DATA_KEY;
 905        key.offset = split;
 906
 907        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 908        if (ret < 0)
 909                goto out;
 910        if (ret > 0 && path->slots[0] > 0)
 911                path->slots[0]--;
 912
 913        leaf = path->nodes[0];
 914        btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 915        BUG_ON(key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY);
 916        fi = btrfs_item_ptr(leaf, path->slots[0],
 917                            struct btrfs_file_extent_item);
 918        BUG_ON(btrfs_file_extent_type(leaf, fi) !=
 919               BTRFS_FILE_EXTENT_PREALLOC);
 920        extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
 921        BUG_ON(key.offset > start || extent_end < end);
 922
 923        bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
 924        num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
 925        orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
 926        memcpy(&new_key, &key, sizeof(new_key));
 927
 928        if (start == key.offset && end < extent_end) {
 929                other_start = 0;
 930                other_end = start;
 931                if (extent_mergeable(leaf, path->slots[0] - 1,
 932                                     ino, bytenr, orig_offset,
 933                                     &other_start, &other_end)) {
 934                        new_key.offset = end;
 935                        btrfs_set_item_key_safe(trans, root, path, &new_key);
 936                        fi = btrfs_item_ptr(leaf, path->slots[0],
 937                                            struct btrfs_file_extent_item);
 938                        btrfs_set_file_extent_num_bytes(leaf, fi,
 939                                                        extent_end - end);
 940                        btrfs_set_file_extent_offset(leaf, fi,
 941                                                     end - orig_offset);
 942                        fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 943                                            struct btrfs_file_extent_item);
 944                        btrfs_set_file_extent_num_bytes(leaf, fi,
 945                                                        end - other_start);
 946                        btrfs_mark_buffer_dirty(leaf);
 947                        goto out;
 948                }
 949        }
 950
 951        if (start > key.offset && end == extent_end) {
 952                other_start = end;
 953                other_end = 0;
 954                if (extent_mergeable(leaf, path->slots[0] + 1,
 955                                     ino, bytenr, orig_offset,
 956                                     &other_start, &other_end)) {
 957                        fi = btrfs_item_ptr(leaf, path->slots[0],
 958                                            struct btrfs_file_extent_item);
 959                        btrfs_set_file_extent_num_bytes(leaf, fi,
 960                                                        start - key.offset);
 961                        path->slots[0]++;
 962                        new_key.offset = start;
 963                        btrfs_set_item_key_safe(trans, root, path, &new_key);
 964
 965                        fi = btrfs_item_ptr(leaf, path->slots[0],
 966                                            struct btrfs_file_extent_item);
 967                        btrfs_set_file_extent_num_bytes(leaf, fi,
 968                                                        other_end - start);
 969                        btrfs_set_file_extent_offset(leaf, fi,
 970                                                     start - orig_offset);
 971                        btrfs_mark_buffer_dirty(leaf);
 972                        goto out;
 973                }
 974        }
 975
 976        while (start > key.offset || end < extent_end) {
 977                if (key.offset == start)
 978                        split = end;
 979
 980                new_key.offset = split;
 981                ret = btrfs_duplicate_item(trans, root, path, &new_key);
 982                if (ret == -EAGAIN) {
 983                        btrfs_release_path(path);
 984                        goto again;
 985                }
 986                if (ret < 0) {
 987                        btrfs_abort_transaction(trans, root, ret);
 988                        goto out;
 989                }
 990
 991                leaf = path->nodes[0];
 992                fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
 993                                    struct btrfs_file_extent_item);
 994                btrfs_set_file_extent_num_bytes(leaf, fi,
 995                                                split - key.offset);
 996
 997                fi = btrfs_item_ptr(leaf, path->slots[0],
 998                                    struct btrfs_file_extent_item);
 999
1000                btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
1001                btrfs_set_file_extent_num_bytes(leaf, fi,
1002                                                extent_end - split);
1003                btrfs_mark_buffer_dirty(leaf);
1004
1005                ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
1006                                           root->root_key.objectid,
1007                                           ino, orig_offset, 0);
1008                BUG_ON(ret); /* -ENOMEM */
1009
1010                if (split == start) {
1011                        key.offset = start;
1012                } else {
1013                        BUG_ON(start != key.offset);
1014                        path->slots[0]--;
1015                        extent_end = end;
1016                }
1017                recow = 1;
1018        }
1019
1020        other_start = end;
1021        other_end = 0;
1022        if (extent_mergeable(leaf, path->slots[0] + 1,
1023                             ino, bytenr, orig_offset,
1024                             &other_start, &other_end)) {
1025                if (recow) {
1026                        btrfs_release_path(path);
1027                        goto again;
1028                }
1029                extent_end = other_end;
1030                del_slot = path->slots[0] + 1;
1031                del_nr++;
1032                ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1033                                        0, root->root_key.objectid,
1034                                        ino, orig_offset, 0);
1035                BUG_ON(ret); /* -ENOMEM */
1036        }
1037        other_start = 0;
1038        other_end = start;
1039        if (extent_mergeable(leaf, path->slots[0] - 1,
1040                             ino, bytenr, orig_offset,
1041                             &other_start, &other_end)) {
1042                if (recow) {
1043                        btrfs_release_path(path);
1044                        goto again;
1045                }
1046                key.offset = other_start;
1047                del_slot = path->slots[0];
1048                del_nr++;
1049                ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1050                                        0, root->root_key.objectid,
1051                                        ino, orig_offset, 0);
1052                BUG_ON(ret); /* -ENOMEM */
1053        }
1054        if (del_nr == 0) {
1055                fi = btrfs_item_ptr(leaf, path->slots[0],
1056                           struct btrfs_file_extent_item);
1057                btrfs_set_file_extent_type(leaf, fi,
1058                                           BTRFS_FILE_EXTENT_REG);
1059                btrfs_mark_buffer_dirty(leaf);
1060        } else {
1061                fi = btrfs_item_ptr(leaf, del_slot - 1,
1062                           struct btrfs_file_extent_item);
1063                btrfs_set_file_extent_type(leaf, fi,
1064                                           BTRFS_FILE_EXTENT_REG);
1065                btrfs_set_file_extent_num_bytes(leaf, fi,
1066                                                extent_end - key.offset);
1067                btrfs_mark_buffer_dirty(leaf);
1068
1069                ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1070                if (ret < 0) {
1071                        btrfs_abort_transaction(trans, root, ret);
1072                        goto out;
1073                }
1074        }
1075out:
1076        btrfs_free_path(path);
1077        return 0;
1078}
1079
1080/*
1081 * on error we return an unlocked page and the error value
1082 * on success we return a locked page and 0
1083 */
1084static int prepare_uptodate_page(struct page *page, u64 pos,
1085                                 bool force_uptodate)
1086{
1087        int ret = 0;
1088
1089        if (((pos & (PAGE_CACHE_SIZE - 1)) || force_uptodate) &&
1090            !PageUptodate(page)) {
1091                ret = btrfs_readpage(NULL, page);
1092                if (ret)
1093                        return ret;
1094                lock_page(page);
1095                if (!PageUptodate(page)) {
1096                        unlock_page(page);
1097                        return -EIO;
1098                }
1099        }
1100        return 0;
1101}
1102
1103/*
1104 * this gets pages into the page cache and locks them down, it also properly
1105 * waits for data=ordered extents to finish before allowing the pages to be
1106 * modified.
1107 */
1108static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
1109                         struct page **pages, size_t num_pages,
1110                         loff_t pos, unsigned long first_index,
1111                         size_t write_bytes, bool force_uptodate)
1112{
1113        struct extent_state *cached_state = NULL;
1114        int i;
1115        unsigned long index = pos >> PAGE_CACHE_SHIFT;
1116        struct inode *inode = fdentry(file)->d_inode;
1117        gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1118        int err = 0;
1119        int faili = 0;
1120        u64 start_pos;
1121        u64 last_pos;
1122
1123        start_pos = pos & ~((u64)root->sectorsize - 1);
1124        last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
1125
1126again:
1127        for (i = 0; i < num_pages; i++) {
1128                pages[i] = find_or_create_page(inode->i_mapping, index + i,
1129                                               mask | __GFP_WRITE);
1130                if (!pages[i]) {
1131                        faili = i - 1;
1132                        err = -ENOMEM;
1133                        goto fail;
1134                }
1135
1136                if (i == 0)
1137                        err = prepare_uptodate_page(pages[i], pos,
1138                                                    force_uptodate);
1139                if (i == num_pages - 1)
1140                        err = prepare_uptodate_page(pages[i],
1141                                                    pos + write_bytes, false);
1142                if (err) {
1143                        page_cache_release(pages[i]);
1144                        faili = i - 1;
1145                        goto fail;
1146                }
1147                wait_on_page_writeback(pages[i]);
1148        }
1149        err = 0;
1150        if (start_pos < inode->i_size) {
1151                struct btrfs_ordered_extent *ordered;
1152                lock_extent_bits(&BTRFS_I(inode)->io_tree,
1153                                 start_pos, last_pos - 1, 0, &cached_state);
1154                ordered = btrfs_lookup_first_ordered_extent(inode,
1155                                                            last_pos - 1);
1156                if (ordered &&
1157                    ordered->file_offset + ordered->len > start_pos &&
1158                    ordered->file_offset < last_pos) {
1159                        btrfs_put_ordered_extent(ordered);
1160                        unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1161                                             start_pos, last_pos - 1,
1162                                             &cached_state, GFP_NOFS);
1163                        for (i = 0; i < num_pages; i++) {
1164                                unlock_page(pages[i]);
1165                                page_cache_release(pages[i]);
1166                        }
1167                        btrfs_wait_ordered_range(inode, start_pos,
1168                                                 last_pos - start_pos);
1169                        goto again;
1170                }
1171                if (ordered)
1172                        btrfs_put_ordered_extent(ordered);
1173
1174                clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1175                                  last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
1176                                  EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
1177                                  GFP_NOFS);
1178                unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1179                                     start_pos, last_pos - 1, &cached_state,
1180                                     GFP_NOFS);
1181        }
1182        for (i = 0; i < num_pages; i++) {
1183                if (clear_page_dirty_for_io(pages[i]))
1184                        account_page_redirty(pages[i]);
1185                set_page_extent_mapped(pages[i]);
1186                WARN_ON(!PageLocked(pages[i]));
1187        }
1188        return 0;
1189fail:
1190        while (faili >= 0) {
1191                unlock_page(pages[faili]);
1192                page_cache_release(pages[faili]);
1193                faili--;
1194        }
1195        return err;
1196
1197}
1198
1199static noinline ssize_t __btrfs_buffered_write(struct file *file,
1200                                               struct iov_iter *i,
1201                                               loff_t pos)
1202{
1203        struct inode *inode = fdentry(file)->d_inode;
1204        struct btrfs_root *root = BTRFS_I(inode)->root;
1205        struct page **pages = NULL;
1206        unsigned long first_index;
1207        size_t num_written = 0;
1208        int nrptrs;
1209        int ret = 0;
1210        bool force_page_uptodate = false;
1211
1212        nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
1213                     PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
1214                     (sizeof(struct page *)));
1215        nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1216        nrptrs = max(nrptrs, 8);
1217        pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1218        if (!pages)
1219                return -ENOMEM;
1220
1221        first_index = pos >> PAGE_CACHE_SHIFT;
1222
1223        while (iov_iter_count(i) > 0) {
1224                size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1225                size_t write_bytes = min(iov_iter_count(i),
1226                                         nrptrs * (size_t)PAGE_CACHE_SIZE -
1227                                         offset);
1228                size_t num_pages = (write_bytes + offset +
1229                                    PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1230                size_t dirty_pages;
1231                size_t copied;
1232
1233                WARN_ON(num_pages > nrptrs);
1234
1235                /*
1236                 * Fault pages before locking them in prepare_pages
1237                 * to avoid recursive lock
1238                 */
1239                if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1240                        ret = -EFAULT;
1241                        break;
1242                }
1243
1244                ret = btrfs_delalloc_reserve_space(inode,
1245                                        num_pages << PAGE_CACHE_SHIFT);
1246                if (ret)
1247                        break;
1248
1249                /*
1250                 * This is going to setup the pages array with the number of
1251                 * pages we want, so we don't really need to worry about the
1252                 * contents of pages from loop to loop
1253                 */
1254                ret = prepare_pages(root, file, pages, num_pages,
1255                                    pos, first_index, write_bytes,
1256                                    force_page_uptodate);
1257                if (ret) {
1258                        btrfs_delalloc_release_space(inode,
1259                                        num_pages << PAGE_CACHE_SHIFT);
1260                        break;
1261                }
1262
1263                copied = btrfs_copy_from_user(pos, num_pages,
1264                                           write_bytes, pages, i);
1265
1266                /*
1267                 * if we have trouble faulting in the pages, fall
1268                 * back to one page at a time
1269                 */
1270                if (copied < write_bytes)
1271                        nrptrs = 1;
1272
1273                if (copied == 0) {
1274                        force_page_uptodate = true;
1275                        dirty_pages = 0;
1276                } else {
1277                        force_page_uptodate = false;
1278                        dirty_pages = (copied + offset +
1279                                       PAGE_CACHE_SIZE - 1) >>
1280                                       PAGE_CACHE_SHIFT;
1281                }
1282
1283                /*
1284                 * If we had a short copy we need to release the excess delaloc
1285                 * bytes we reserved.  We need to increment outstanding_extents
1286                 * because btrfs_delalloc_release_space will decrement it, but
1287                 * we still have an outstanding extent for the chunk we actually
1288                 * managed to copy.
1289                 */
1290                if (num_pages > dirty_pages) {
1291                        if (copied > 0) {
1292                                spin_lock(&BTRFS_I(inode)->lock);
1293                                BTRFS_I(inode)->outstanding_extents++;
1294                                spin_unlock(&BTRFS_I(inode)->lock);
1295                        }
1296                        btrfs_delalloc_release_space(inode,
1297                                        (num_pages - dirty_pages) <<
1298                                        PAGE_CACHE_SHIFT);
1299                }
1300
1301                if (copied > 0) {
1302                        ret = btrfs_dirty_pages(root, inode, pages,
1303                                                dirty_pages, pos, copied,
1304                                                NULL);
1305                        if (ret) {
1306                                btrfs_delalloc_release_space(inode,
1307                                        dirty_pages << PAGE_CACHE_SHIFT);
1308                                btrfs_drop_pages(pages, num_pages);
1309                                break;
1310                        }
1311                }
1312
1313                btrfs_drop_pages(pages, num_pages);
1314
1315                cond_resched();
1316
1317                balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1318                                                   dirty_pages);
1319                if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1320                        btrfs_btree_balance_dirty(root, 1);
1321
1322                pos += copied;
1323                num_written += copied;
1324        }
1325
1326        kfree(pages);
1327
1328        return num_written ? num_written : ret;
1329}
1330
1331static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1332                                    const struct iovec *iov,
1333                                    unsigned long nr_segs, loff_t pos,
1334                                    loff_t *ppos, size_t count, size_t ocount)
1335{
1336        struct file *file = iocb->ki_filp;
1337        struct iov_iter i;
1338        ssize_t written;
1339        ssize_t written_buffered;
1340        loff_t endbyte;
1341        int err;
1342
1343        written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
1344                                            count, ocount);
1345
1346        if (written < 0 || written == count)
1347                return written;
1348
1349        pos += written;
1350        count -= written;
1351        iov_iter_init(&i, iov, nr_segs, count, written);
1352        written_buffered = __btrfs_buffered_write(file, &i, pos);
1353        if (written_buffered < 0) {
1354                err = written_buffered;
1355                goto out;
1356        }
1357        endbyte = pos + written_buffered - 1;
1358        err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
1359        if (err)
1360                goto out;
1361        written += written_buffered;
1362        *ppos = pos + written_buffered;
1363        invalidate_mapping_pages(file->f_mapping, pos >> PAGE_CACHE_SHIFT,
1364                                 endbyte >> PAGE_CACHE_SHIFT);
1365out:
1366        return written ? written : err;
1367}
1368
1369static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
1370                                    const struct iovec *iov,
1371                                    unsigned long nr_segs, loff_t pos)
1372{
1373        struct file *file = iocb->ki_filp;
1374        struct inode *inode = fdentry(file)->d_inode;
1375        struct btrfs_root *root = BTRFS_I(inode)->root;
1376        loff_t *ppos = &iocb->ki_pos;
1377        u64 start_pos;
1378        ssize_t num_written = 0;
1379        ssize_t err = 0;
1380        size_t count, ocount;
1381
1382        sb_start_write(inode->i_sb);
1383
1384        mutex_lock(&inode->i_mutex);
1385
1386        err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1387        if (err) {
1388                mutex_unlock(&inode->i_mutex);
1389                goto out;
1390        }
1391        count = ocount;
1392
1393        current->backing_dev_info = inode->i_mapping->backing_dev_info;
1394        err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1395        if (err) {
1396                mutex_unlock(&inode->i_mutex);
1397                goto out;
1398        }
1399
1400        if (count == 0) {
1401                mutex_unlock(&inode->i_mutex);
1402                goto out;
1403        }
1404
1405        err = file_remove_suid(file);
1406        if (err) {
1407                mutex_unlock(&inode->i_mutex);
1408                goto out;
1409        }
1410
1411        /*
1412         * If BTRFS flips readonly due to some impossible error
1413         * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1414         * although we have opened a file as writable, we have
1415         * to stop this write operation to ensure FS consistency.
1416         */
1417        if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
1418                mutex_unlock(&inode->i_mutex);
1419                err = -EROFS;
1420                goto out;
1421        }
1422
1423        err = file_update_time(file);
1424        if (err) {
1425                mutex_unlock(&inode->i_mutex);
1426                goto out;
1427        }
1428
1429        start_pos = round_down(pos, root->sectorsize);
1430        if (start_pos > i_size_read(inode)) {
1431                err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
1432                if (err) {
1433                        mutex_unlock(&inode->i_mutex);
1434                        goto out;
1435                }
1436        }
1437
1438        if (unlikely(file->f_flags & O_DIRECT)) {
1439                num_written = __btrfs_direct_write(iocb, iov, nr_segs,
1440                                                   pos, ppos, count, ocount);
1441        } else {
1442                struct iov_iter i;
1443
1444                iov_iter_init(&i, iov, nr_segs, count, num_written);
1445
1446                num_written = __btrfs_buffered_write(file, &i, pos);
1447                if (num_written > 0)
1448                        *ppos = pos + num_written;
1449        }
1450
1451        mutex_unlock(&inode->i_mutex);
1452
1453        /*
1454         * we want to make sure fsync finds this change
1455         * but we haven't joined a transaction running right now.
1456         *
1457         * Later on, someone is sure to update the inode and get the
1458         * real transid recorded.
1459         *
1460         * We set last_trans now to the fs_info generation + 1,
1461         * this will either be one more than the running transaction
1462         * or the generation used for the next transaction if there isn't
1463         * one running right now.
1464         */
1465        BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1466        if (num_written > 0 || num_written == -EIOCBQUEUED) {
1467                err = generic_write_sync(file, pos, num_written);
1468                if (err < 0 && num_written > 0)
1469                        num_written = err;
1470        }
1471out:
1472        sb_end_write(inode->i_sb);
1473        current->backing_dev_info = NULL;
1474        return num_written ? num_written : err;
1475}
1476
1477int btrfs_release_file(struct inode *inode, struct file *filp)
1478{
1479        /*
1480         * ordered_data_close is set by settattr when we are about to truncate
1481         * a file from a non-zero size to a zero size.  This tries to
1482         * flush down new bytes that may have been written if the
1483         * application were using truncate to replace a file in place.
1484         */
1485        if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
1486                               &BTRFS_I(inode)->runtime_flags)) {
1487                btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1488                if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1489                        filemap_flush(inode->i_mapping);
1490        }
1491        if (filp->private_data)
1492                btrfs_ioctl_trans_end(filp);
1493        return 0;
1494}
1495
1496/*
1497 * fsync call for both files and directories.  This logs the inode into
1498 * the tree log instead of forcing full commits whenever possible.
1499 *
1500 * It needs to call filemap_fdatawait so that all ordered extent updates are
1501 * in the metadata btree are up to date for copying to the log.
1502 *
1503 * It drops the inode mutex before doing the tree log commit.  This is an
1504 * important optimization for directories because holding the mutex prevents
1505 * new operations on the dir while we write to disk.
1506 */
1507int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
1508{
1509        struct dentry *dentry = file->f_path.dentry;
1510        struct inode *inode = dentry->d_inode;
1511        struct btrfs_root *root = BTRFS_I(inode)->root;
1512        int ret = 0;
1513        struct btrfs_trans_handle *trans;
1514
1515        trace_btrfs_sync_file(file, datasync);
1516
1517        mutex_lock(&inode->i_mutex);
1518
1519        /*
1520         * we wait first, since the writeback may change the inode, also wait
1521         * ordered range does a filemape_write_and_wait_range which is why we
1522         * don't do it above like other file systems.
1523         */
1524        root->log_batch++;
1525        btrfs_wait_ordered_range(inode, start, end);
1526        root->log_batch++;
1527
1528        /*
1529         * check the transaction that last modified this inode
1530         * and see if its already been committed
1531         */
1532        if (!BTRFS_I(inode)->last_trans) {
1533                mutex_unlock(&inode->i_mutex);
1534                goto out;
1535        }
1536
1537        /*
1538         * if the last transaction that changed this file was before
1539         * the current transaction, we can bail out now without any
1540         * syncing
1541         */
1542        smp_mb();
1543        if (btrfs_inode_in_log(inode, root->fs_info->generation) ||
1544            BTRFS_I(inode)->last_trans <=
1545            root->fs_info->last_trans_committed) {
1546                BTRFS_I(inode)->last_trans = 0;
1547                mutex_unlock(&inode->i_mutex);
1548                goto out;
1549        }
1550
1551        /*
1552         * ok we haven't committed the transaction yet, lets do a commit
1553         */
1554        if (file->private_data)
1555                btrfs_ioctl_trans_end(file);
1556
1557        trans = btrfs_start_transaction(root, 0);
1558        if (IS_ERR(trans)) {
1559                ret = PTR_ERR(trans);
1560                mutex_unlock(&inode->i_mutex);
1561                goto out;
1562        }
1563
1564        ret = btrfs_log_dentry_safe(trans, root, dentry);
1565        if (ret < 0) {
1566                mutex_unlock(&inode->i_mutex);
1567                goto out;
1568        }
1569
1570        /* we've logged all the items and now have a consistent
1571         * version of the file in the log.  It is possible that
1572         * someone will come in and modify the file, but that's
1573         * fine because the log is consistent on disk, and we
1574         * have references to all of the file's extents
1575         *
1576         * It is possible that someone will come in and log the
1577         * file again, but that will end up using the synchronization
1578         * inside btrfs_sync_log to keep things safe.
1579         */
1580        mutex_unlock(&inode->i_mutex);
1581
1582        if (ret != BTRFS_NO_LOG_SYNC) {
1583                if (ret > 0) {
1584                        ret = btrfs_commit_transaction(trans, root);
1585                } else {
1586                        ret = btrfs_sync_log(trans, root);
1587                        if (ret == 0)
1588                                ret = btrfs_end_transaction(trans, root);
1589                        else
1590                                ret = btrfs_commit_transaction(trans, root);
1591                }
1592        } else {
1593                ret = btrfs_end_transaction(trans, root);
1594        }
1595out:
1596        return ret > 0 ? -EIO : ret;
1597}
1598
1599static const struct vm_operations_struct btrfs_file_vm_ops = {
1600        .fault          = filemap_fault,
1601        .page_mkwrite   = btrfs_page_mkwrite,
1602};
1603
1604static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1605{
1606        struct address_space *mapping = filp->f_mapping;
1607
1608        if (!mapping->a_ops->readpage)
1609                return -ENOEXEC;
1610
1611        file_accessed(filp);
1612        vma->vm_ops = &btrfs_file_vm_ops;
1613        vma->vm_flags |= VM_CAN_NONLINEAR;
1614
1615        return 0;
1616}
1617
1618static long btrfs_fallocate(struct file *file, int mode,
1619                            loff_t offset, loff_t len)
1620{
1621        struct inode *inode = file->f_path.dentry->d_inode;
1622        struct extent_state *cached_state = NULL;
1623        u64 cur_offset;
1624        u64 last_byte;
1625        u64 alloc_start;
1626        u64 alloc_end;
1627        u64 alloc_hint = 0;
1628        u64 locked_end;
1629        u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1630        struct extent_map *em;
1631        int ret;
1632
1633        alloc_start = offset & ~mask;
1634        alloc_end =  (offset + len + mask) & ~mask;
1635
1636        /* We only support the FALLOC_FL_KEEP_SIZE mode */
1637        if (mode & ~FALLOC_FL_KEEP_SIZE)
1638                return -EOPNOTSUPP;
1639
1640        /*
1641         * Make sure we have enough space before we do the
1642         * allocation.
1643         */
1644        ret = btrfs_check_data_free_space(inode, len);
1645        if (ret)
1646                return ret;
1647
1648        /*
1649         * wait for ordered IO before we have any locks.  We'll loop again
1650         * below with the locks held.
1651         */
1652        btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1653
1654        mutex_lock(&inode->i_mutex);
1655        ret = inode_newsize_ok(inode, alloc_end);
1656        if (ret)
1657                goto out;
1658
1659        if (alloc_start > inode->i_size) {
1660                ret = btrfs_cont_expand(inode, i_size_read(inode),
1661                                        alloc_start);
1662                if (ret)
1663                        goto out;
1664        }
1665
1666        locked_end = alloc_end - 1;
1667        while (1) {
1668                struct btrfs_ordered_extent *ordered;
1669
1670                /* the extent lock is ordered inside the running
1671                 * transaction
1672                 */
1673                lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1674                                 locked_end, 0, &cached_state);
1675                ordered = btrfs_lookup_first_ordered_extent(inode,
1676                                                            alloc_end - 1);
1677                if (ordered &&
1678                    ordered->file_offset + ordered->len > alloc_start &&
1679                    ordered->file_offset < alloc_end) {
1680                        btrfs_put_ordered_extent(ordered);
1681                        unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1682                                             alloc_start, locked_end,
1683                                             &cached_state, GFP_NOFS);
1684                        /*
1685                         * we can't wait on the range with the transaction
1686                         * running or with the extent lock held
1687                         */
1688                        btrfs_wait_ordered_range(inode, alloc_start,
1689                                                 alloc_end - alloc_start);
1690                } else {
1691                        if (ordered)
1692                                btrfs_put_ordered_extent(ordered);
1693                        break;
1694                }
1695        }
1696
1697        cur_offset = alloc_start;
1698        while (1) {
1699                u64 actual_end;
1700
1701                em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1702                                      alloc_end - cur_offset, 0);
1703                if (IS_ERR_OR_NULL(em)) {
1704                        if (!em)
1705                                ret = -ENOMEM;
1706                        else
1707                                ret = PTR_ERR(em);
1708                        break;
1709                }
1710                last_byte = min(extent_map_end(em), alloc_end);
1711                actual_end = min_t(u64, extent_map_end(em), offset + len);
1712                last_byte = (last_byte + mask) & ~mask;
1713
1714                if (em->block_start == EXTENT_MAP_HOLE ||
1715                    (cur_offset >= inode->i_size &&
1716                     !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1717                        ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1718                                                        last_byte - cur_offset,
1719                                                        1 << inode->i_blkbits,
1720                                                        offset + len,
1721                                                        &alloc_hint);
1722
1723                        if (ret < 0) {
1724                                free_extent_map(em);
1725                                break;
1726                        }
1727                } else if (actual_end > inode->i_size &&
1728                           !(mode & FALLOC_FL_KEEP_SIZE)) {
1729                        /*
1730                         * We didn't need to allocate any more space, but we
1731                         * still extended the size of the file so we need to
1732                         * update i_size.
1733                         */
1734                        inode->i_ctime = CURRENT_TIME;
1735                        i_size_write(inode, actual_end);
1736                        btrfs_ordered_update_i_size(inode, actual_end, NULL);
1737                }
1738                free_extent_map(em);
1739
1740                cur_offset = last_byte;
1741                if (cur_offset >= alloc_end) {
1742                        ret = 0;
1743                        break;
1744                }
1745        }
1746        unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1747                             &cached_state, GFP_NOFS);
1748out:
1749        mutex_unlock(&inode->i_mutex);
1750        /* Let go of our reservation. */
1751        btrfs_free_reserved_data_space(inode, len);
1752        return ret;
1753}
1754
1755static int find_desired_extent(struct inode *inode, loff_t *offset, int origin)
1756{
1757        struct btrfs_root *root = BTRFS_I(inode)->root;
1758        struct extent_map *em;
1759        struct extent_state *cached_state = NULL;
1760        u64 lockstart = *offset;
1761        u64 lockend = i_size_read(inode);
1762        u64 start = *offset;
1763        u64 orig_start = *offset;
1764        u64 len = i_size_read(inode);
1765        u64 last_end = 0;
1766        int ret = 0;
1767
1768        lockend = max_t(u64, root->sectorsize, lockend);
1769        if (lockend <= lockstart)
1770                lockend = lockstart + root->sectorsize;
1771
1772        len = lockend - lockstart + 1;
1773
1774        len = max_t(u64, len, root->sectorsize);
1775        if (inode->i_size == 0)
1776                return -ENXIO;
1777
1778        lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, 0,
1779                         &cached_state);
1780
1781        /*
1782         * Delalloc is such a pain.  If we have a hole and we have pending
1783         * delalloc for a portion of the hole we will get back a hole that
1784         * exists for the entire range since it hasn't been actually written
1785         * yet.  So to take care of this case we need to look for an extent just
1786         * before the position we want in case there is outstanding delalloc
1787         * going on here.
1788         */
1789        if (origin == SEEK_HOLE && start != 0) {
1790                if (start <= root->sectorsize)
1791                        em = btrfs_get_extent_fiemap(inode, NULL, 0, 0,
1792                                                     root->sectorsize, 0);
1793                else
1794                        em = btrfs_get_extent_fiemap(inode, NULL, 0,
1795                                                     start - root->sectorsize,
1796                                                     root->sectorsize, 0);
1797                if (IS_ERR(em)) {
1798                        ret = PTR_ERR(em);
1799                        goto out;
1800                }
1801                last_end = em->start + em->len;
1802                if (em->block_start == EXTENT_MAP_DELALLOC)
1803                        last_end = min_t(u64, last_end, inode->i_size);
1804                free_extent_map(em);
1805        }
1806
1807        while (1) {
1808                em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0);
1809                if (IS_ERR(em)) {
1810                        ret = PTR_ERR(em);
1811                        break;
1812                }
1813
1814                if (em->block_start == EXTENT_MAP_HOLE) {
1815                        if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
1816                                if (last_end <= orig_start) {
1817                                        free_extent_map(em);
1818                                        ret = -ENXIO;
1819                                        break;
1820                                }
1821                        }
1822
1823                        if (origin == SEEK_HOLE) {
1824                                *offset = start;
1825                                free_extent_map(em);
1826                                break;
1827                        }
1828                } else {
1829                        if (origin == SEEK_DATA) {
1830                                if (em->block_start == EXTENT_MAP_DELALLOC) {
1831                                        if (start >= inode->i_size) {
1832                                                free_extent_map(em);
1833                                                ret = -ENXIO;
1834                                                break;
1835                                        }
1836                                }
1837
1838                                *offset = start;
1839                                free_extent_map(em);
1840                                break;
1841                        }
1842                }
1843
1844                start = em->start + em->len;
1845                last_end = em->start + em->len;
1846
1847                if (em->block_start == EXTENT_MAP_DELALLOC)
1848                        last_end = min_t(u64, last_end, inode->i_size);
1849
1850                if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
1851                        free_extent_map(em);
1852                        ret = -ENXIO;
1853                        break;
1854                }
1855                free_extent_map(em);
1856                cond_resched();
1857        }
1858        if (!ret)
1859                *offset = min(*offset, inode->i_size);
1860out:
1861        unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
1862                             &cached_state, GFP_NOFS);
1863        return ret;
1864}
1865
1866static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
1867{
1868        struct inode *inode = file->f_mapping->host;
1869        int ret;
1870
1871        mutex_lock(&inode->i_mutex);
1872        switch (origin) {
1873        case SEEK_END:
1874        case SEEK_CUR:
1875                offset = generic_file_llseek(file, offset, origin);
1876                goto out;
1877        case SEEK_DATA:
1878        case SEEK_HOLE:
1879                if (offset >= i_size_read(inode)) {
1880                        mutex_unlock(&inode->i_mutex);
1881                        return -ENXIO;
1882                }
1883
1884                ret = find_desired_extent(inode, &offset, origin);
1885                if (ret) {
1886                        mutex_unlock(&inode->i_mutex);
1887                        return ret;
1888                }
1889        }
1890
1891        if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
1892                offset = -EINVAL;
1893                goto out;
1894        }
1895        if (offset > inode->i_sb->s_maxbytes) {
1896                offset = -EINVAL;
1897                goto out;
1898        }
1899
1900        /* Special lock needed here? */
1901        if (offset != file->f_pos) {
1902                file->f_pos = offset;
1903                file->f_version = 0;
1904        }
1905out:
1906        mutex_unlock(&inode->i_mutex);
1907        return offset;
1908}
1909
1910const struct file_operations btrfs_file_operations = {
1911        .llseek         = btrfs_file_llseek,
1912        .read           = do_sync_read,
1913        .write          = do_sync_write,
1914        .aio_read       = generic_file_aio_read,
1915        .splice_read    = generic_file_splice_read,
1916        .aio_write      = btrfs_file_aio_write,
1917        .mmap           = btrfs_file_mmap,
1918        .open           = generic_file_open,
1919        .release        = btrfs_release_file,
1920        .fsync          = btrfs_sync_file,
1921        .fallocate      = btrfs_fallocate,
1922        .unlocked_ioctl = btrfs_ioctl,
1923#ifdef CONFIG_COMPAT
1924        .compat_ioctl   = btrfs_ioctl,
1925#endif
1926};
1927
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