linux/fs/gfs2/aops.c
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   1/*
   2 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3 * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   4 *
   5 * This copyrighted material is made available to anyone wishing to use,
   6 * modify, copy, or redistribute it subject to the terms and conditions
   7 * of the GNU General Public License version 2.
   8 */
   9
  10#include <linux/sched.h>
  11#include <linux/slab.h>
  12#include <linux/spinlock.h>
  13#include <linux/completion.h>
  14#include <linux/buffer_head.h>
  15#include <linux/pagemap.h>
  16#include <linux/pagevec.h>
  17#include <linux/mpage.h>
  18#include <linux/fs.h>
  19#include <linux/writeback.h>
  20#include <linux/swap.h>
  21#include <linux/gfs2_ondisk.h>
  22#include <linux/backing-dev.h>
  23
  24#include "gfs2.h"
  25#include "incore.h"
  26#include "bmap.h"
  27#include "glock.h"
  28#include "inode.h"
  29#include "log.h"
  30#include "meta_io.h"
  31#include "quota.h"
  32#include "trans.h"
  33#include "rgrp.h"
  34#include "super.h"
  35#include "util.h"
  36#include "glops.h"
  37
  38
  39static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  40                                   unsigned int from, unsigned int to)
  41{
  42        struct buffer_head *head = page_buffers(page);
  43        unsigned int bsize = head->b_size;
  44        struct buffer_head *bh;
  45        unsigned int start, end;
  46
  47        for (bh = head, start = 0; bh != head || !start;
  48             bh = bh->b_this_page, start = end) {
  49                end = start + bsize;
  50                if (end <= from || start >= to)
  51                        continue;
  52                if (gfs2_is_jdata(ip))
  53                        set_buffer_uptodate(bh);
  54                gfs2_trans_add_bh(ip->i_gl, bh, 0);
  55        }
  56}
  57
  58/**
  59 * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  60 * @inode: The inode
  61 * @lblock: The block number to look up
  62 * @bh_result: The buffer head to return the result in
  63 * @create: Non-zero if we may add block to the file
  64 *
  65 * Returns: errno
  66 */
  67
  68static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  69                                  struct buffer_head *bh_result, int create)
  70{
  71        int error;
  72
  73        error = gfs2_block_map(inode, lblock, bh_result, 0);
  74        if (error)
  75                return error;
  76        if (!buffer_mapped(bh_result))
  77                return -EIO;
  78        return 0;
  79}
  80
  81static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  82                                 struct buffer_head *bh_result, int create)
  83{
  84        return gfs2_block_map(inode, lblock, bh_result, 0);
  85}
  86
  87/**
  88 * gfs2_writepage_common - Common bits of writepage
  89 * @page: The page to be written
  90 * @wbc: The writeback control
  91 *
  92 * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
  93 */
  94
  95static int gfs2_writepage_common(struct page *page,
  96                                 struct writeback_control *wbc)
  97{
  98        struct inode *inode = page->mapping->host;
  99        struct gfs2_inode *ip = GFS2_I(inode);
 100        struct gfs2_sbd *sdp = GFS2_SB(inode);
 101        loff_t i_size = i_size_read(inode);
 102        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 103        unsigned offset;
 104
 105        if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 106                goto out;
 107        if (current->journal_info)
 108                goto redirty;
 109        /* Is the page fully outside i_size? (truncate in progress) */
 110        offset = i_size & (PAGE_CACHE_SIZE-1);
 111        if (page->index > end_index || (page->index == end_index && !offset)) {
 112                page->mapping->a_ops->invalidatepage(page, 0);
 113                goto out;
 114        }
 115        return 1;
 116redirty:
 117        redirty_page_for_writepage(wbc, page);
 118out:
 119        unlock_page(page);
 120        return 0;
 121}
 122
 123/**
 124 * gfs2_writeback_writepage - Write page for writeback mappings
 125 * @page: The page
 126 * @wbc: The writeback control
 127 *
 128 */
 129
 130static int gfs2_writeback_writepage(struct page *page,
 131                                    struct writeback_control *wbc)
 132{
 133        int ret;
 134
 135        ret = gfs2_writepage_common(page, wbc);
 136        if (ret <= 0)
 137                return ret;
 138
 139        return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
 140}
 141
 142/**
 143 * gfs2_ordered_writepage - Write page for ordered data files
 144 * @page: The page to write
 145 * @wbc: The writeback control
 146 *
 147 */
 148
 149static int gfs2_ordered_writepage(struct page *page,
 150                                  struct writeback_control *wbc)
 151{
 152        struct inode *inode = page->mapping->host;
 153        struct gfs2_inode *ip = GFS2_I(inode);
 154        int ret;
 155
 156        ret = gfs2_writepage_common(page, wbc);
 157        if (ret <= 0)
 158                return ret;
 159
 160        if (!page_has_buffers(page)) {
 161                create_empty_buffers(page, inode->i_sb->s_blocksize,
 162                                     (1 << BH_Dirty)|(1 << BH_Uptodate));
 163        }
 164        gfs2_page_add_databufs(ip, page, 0, inode->i_sb->s_blocksize-1);
 165        return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 166}
 167
 168/**
 169 * __gfs2_jdata_writepage - The core of jdata writepage
 170 * @page: The page to write
 171 * @wbc: The writeback control
 172 *
 173 * This is shared between writepage and writepages and implements the
 174 * core of the writepage operation. If a transaction is required then
 175 * PageChecked will have been set and the transaction will have
 176 * already been started before this is called.
 177 */
 178
 179static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 180{
 181        struct inode *inode = page->mapping->host;
 182        struct gfs2_inode *ip = GFS2_I(inode);
 183        struct gfs2_sbd *sdp = GFS2_SB(inode);
 184
 185        if (PageChecked(page)) {
 186                ClearPageChecked(page);
 187                if (!page_has_buffers(page)) {
 188                        create_empty_buffers(page, inode->i_sb->s_blocksize,
 189                                             (1 << BH_Dirty)|(1 << BH_Uptodate));
 190                }
 191                gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 192        }
 193        return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 194}
 195
 196/**
 197 * gfs2_jdata_writepage - Write complete page
 198 * @page: Page to write
 199 *
 200 * Returns: errno
 201 *
 202 */
 203
 204static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 205{
 206        struct inode *inode = page->mapping->host;
 207        struct gfs2_sbd *sdp = GFS2_SB(inode);
 208        int ret;
 209        int done_trans = 0;
 210
 211        if (PageChecked(page)) {
 212                if (wbc->sync_mode != WB_SYNC_ALL)
 213                        goto out_ignore;
 214                ret = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 215                if (ret)
 216                        goto out_ignore;
 217                done_trans = 1;
 218        }
 219        ret = gfs2_writepage_common(page, wbc);
 220        if (ret > 0)
 221                ret = __gfs2_jdata_writepage(page, wbc);
 222        if (done_trans)
 223                gfs2_trans_end(sdp);
 224        return ret;
 225
 226out_ignore:
 227        redirty_page_for_writepage(wbc, page);
 228        unlock_page(page);
 229        return 0;
 230}
 231
 232/**
 233 * gfs2_writeback_writepages - Write a bunch of dirty pages back to disk
 234 * @mapping: The mapping to write
 235 * @wbc: Write-back control
 236 *
 237 * For the data=writeback case we can already ignore buffer heads
 238 * and write whole extents at once. This is a big reduction in the
 239 * number of I/O requests we send and the bmap calls we make in this case.
 240 */
 241static int gfs2_writeback_writepages(struct address_space *mapping,
 242                                     struct writeback_control *wbc)
 243{
 244        return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 245}
 246
 247/**
 248 * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 249 * @mapping: The mapping
 250 * @wbc: The writeback control
 251 * @writepage: The writepage function to call for each page
 252 * @pvec: The vector of pages
 253 * @nr_pages: The number of pages to write
 254 *
 255 * Returns: non-zero if loop should terminate, zero otherwise
 256 */
 257
 258static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 259                                    struct writeback_control *wbc,
 260                                    struct pagevec *pvec,
 261                                    int nr_pages, pgoff_t end)
 262{
 263        struct inode *inode = mapping->host;
 264        struct gfs2_sbd *sdp = GFS2_SB(inode);
 265        loff_t i_size = i_size_read(inode);
 266        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 267        unsigned offset = i_size & (PAGE_CACHE_SIZE-1);
 268        unsigned nrblocks = nr_pages * (PAGE_CACHE_SIZE/inode->i_sb->s_blocksize);
 269        int i;
 270        int ret;
 271
 272        ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 273        if (ret < 0)
 274                return ret;
 275
 276        for(i = 0; i < nr_pages; i++) {
 277                struct page *page = pvec->pages[i];
 278
 279                lock_page(page);
 280
 281                if (unlikely(page->mapping != mapping)) {
 282                        unlock_page(page);
 283                        continue;
 284                }
 285
 286                if (!wbc->range_cyclic && page->index > end) {
 287                        ret = 1;
 288                        unlock_page(page);
 289                        continue;
 290                }
 291
 292                if (wbc->sync_mode != WB_SYNC_NONE)
 293                        wait_on_page_writeback(page);
 294
 295                if (PageWriteback(page) ||
 296                    !clear_page_dirty_for_io(page)) {
 297                        unlock_page(page);
 298                        continue;
 299                }
 300
 301                /* Is the page fully outside i_size? (truncate in progress) */
 302                if (page->index > end_index || (page->index == end_index && !offset)) {
 303                        page->mapping->a_ops->invalidatepage(page, 0);
 304                        unlock_page(page);
 305                        continue;
 306                }
 307
 308                ret = __gfs2_jdata_writepage(page, wbc);
 309
 310                if (ret || (--(wbc->nr_to_write) <= 0))
 311                        ret = 1;
 312        }
 313        gfs2_trans_end(sdp);
 314        return ret;
 315}
 316
 317/**
 318 * gfs2_write_cache_jdata - Like write_cache_pages but different
 319 * @mapping: The mapping to write
 320 * @wbc: The writeback control
 321 * @writepage: The writepage function to call
 322 * @data: The data to pass to writepage
 323 *
 324 * The reason that we use our own function here is that we need to
 325 * start transactions before we grab page locks. This allows us
 326 * to get the ordering right.
 327 */
 328
 329static int gfs2_write_cache_jdata(struct address_space *mapping,
 330                                  struct writeback_control *wbc)
 331{
 332        int ret = 0;
 333        int done = 0;
 334        struct pagevec pvec;
 335        int nr_pages;
 336        pgoff_t index;
 337        pgoff_t end;
 338        int scanned = 0;
 339        int range_whole = 0;
 340
 341        pagevec_init(&pvec, 0);
 342        if (wbc->range_cyclic) {
 343                index = mapping->writeback_index; /* Start from prev offset */
 344                end = -1;
 345        } else {
 346                index = wbc->range_start >> PAGE_CACHE_SHIFT;
 347                end = wbc->range_end >> PAGE_CACHE_SHIFT;
 348                if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 349                        range_whole = 1;
 350                scanned = 1;
 351        }
 352
 353retry:
 354         while (!done && (index <= end) &&
 355                (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 356                                               PAGECACHE_TAG_DIRTY,
 357                                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
 358                scanned = 1;
 359                ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end);
 360                if (ret)
 361                        done = 1;
 362                if (ret > 0)
 363                        ret = 0;
 364
 365                pagevec_release(&pvec);
 366                cond_resched();
 367        }
 368
 369        if (!scanned && !done) {
 370                /*
 371                 * We hit the last page and there is more work to be done: wrap
 372                 * back to the start of the file
 373                 */
 374                scanned = 1;
 375                index = 0;
 376                goto retry;
 377        }
 378
 379        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 380                mapping->writeback_index = index;
 381        return ret;
 382}
 383
 384
 385/**
 386 * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 387 * @mapping: The mapping to write
 388 * @wbc: The writeback control
 389 * 
 390 */
 391
 392static int gfs2_jdata_writepages(struct address_space *mapping,
 393                                 struct writeback_control *wbc)
 394{
 395        struct gfs2_inode *ip = GFS2_I(mapping->host);
 396        struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 397        int ret;
 398
 399        ret = gfs2_write_cache_jdata(mapping, wbc);
 400        if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 401                gfs2_log_flush(sdp, ip->i_gl);
 402                ret = gfs2_write_cache_jdata(mapping, wbc);
 403        }
 404        return ret;
 405}
 406
 407/**
 408 * stuffed_readpage - Fill in a Linux page with stuffed file data
 409 * @ip: the inode
 410 * @page: the page
 411 *
 412 * Returns: errno
 413 */
 414
 415static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 416{
 417        struct buffer_head *dibh;
 418        u64 dsize = i_size_read(&ip->i_inode);
 419        void *kaddr;
 420        int error;
 421
 422        /*
 423         * Due to the order of unstuffing files and ->fault(), we can be
 424         * asked for a zero page in the case of a stuffed file being extended,
 425         * so we need to supply one here. It doesn't happen often.
 426         */
 427        if (unlikely(page->index)) {
 428                zero_user(page, 0, PAGE_CACHE_SIZE);
 429                SetPageUptodate(page);
 430                return 0;
 431        }
 432
 433        error = gfs2_meta_inode_buffer(ip, &dibh);
 434        if (error)
 435                return error;
 436
 437        kaddr = kmap_atomic(page);
 438        if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
 439                dsize = (dibh->b_size - sizeof(struct gfs2_dinode));
 440        memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 441        memset(kaddr + dsize, 0, PAGE_CACHE_SIZE - dsize);
 442        kunmap_atomic(kaddr);
 443        flush_dcache_page(page);
 444        brelse(dibh);
 445        SetPageUptodate(page);
 446
 447        return 0;
 448}
 449
 450
 451/**
 452 * __gfs2_readpage - readpage
 453 * @file: The file to read a page for
 454 * @page: The page to read
 455 *
 456 * This is the core of gfs2's readpage. Its used by the internal file
 457 * reading code as in that case we already hold the glock. Also its
 458 * called by gfs2_readpage() once the required lock has been granted.
 459 *
 460 */
 461
 462static int __gfs2_readpage(void *file, struct page *page)
 463{
 464        struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 465        struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 466        int error;
 467
 468        if (gfs2_is_stuffed(ip)) {
 469                error = stuffed_readpage(ip, page);
 470                unlock_page(page);
 471        } else {
 472                error = mpage_readpage(page, gfs2_block_map);
 473        }
 474
 475        if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 476                return -EIO;
 477
 478        return error;
 479}
 480
 481/**
 482 * gfs2_readpage - read a page of a file
 483 * @file: The file to read
 484 * @page: The page of the file
 485 *
 486 * This deals with the locking required. We have to unlock and
 487 * relock the page in order to get the locking in the right
 488 * order.
 489 */
 490
 491static int gfs2_readpage(struct file *file, struct page *page)
 492{
 493        struct address_space *mapping = page->mapping;
 494        struct gfs2_inode *ip = GFS2_I(mapping->host);
 495        struct gfs2_holder gh;
 496        int error;
 497
 498        unlock_page(page);
 499        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 500        error = gfs2_glock_nq(&gh);
 501        if (unlikely(error))
 502                goto out;
 503        error = AOP_TRUNCATED_PAGE;
 504        lock_page(page);
 505        if (page->mapping == mapping && !PageUptodate(page))
 506                error = __gfs2_readpage(file, page);
 507        else
 508                unlock_page(page);
 509        gfs2_glock_dq(&gh);
 510out:
 511        gfs2_holder_uninit(&gh);
 512        if (error && error != AOP_TRUNCATED_PAGE)
 513                lock_page(page);
 514        return error;
 515}
 516
 517/**
 518 * gfs2_internal_read - read an internal file
 519 * @ip: The gfs2 inode
 520 * @buf: The buffer to fill
 521 * @pos: The file position
 522 * @size: The amount to read
 523 *
 524 */
 525
 526int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
 527                       unsigned size)
 528{
 529        struct address_space *mapping = ip->i_inode.i_mapping;
 530        unsigned long index = *pos / PAGE_CACHE_SIZE;
 531        unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
 532        unsigned copied = 0;
 533        unsigned amt;
 534        struct page *page;
 535        void *p;
 536
 537        do {
 538                amt = size - copied;
 539                if (offset + size > PAGE_CACHE_SIZE)
 540                        amt = PAGE_CACHE_SIZE - offset;
 541                page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
 542                if (IS_ERR(page))
 543                        return PTR_ERR(page);
 544                p = kmap_atomic(page);
 545                memcpy(buf + copied, p + offset, amt);
 546                kunmap_atomic(p);
 547                mark_page_accessed(page);
 548                page_cache_release(page);
 549                copied += amt;
 550                index++;
 551                offset = 0;
 552        } while(copied < size);
 553        (*pos) += size;
 554        return size;
 555}
 556
 557/**
 558 * gfs2_readpages - Read a bunch of pages at once
 559 *
 560 * Some notes:
 561 * 1. This is only for readahead, so we can simply ignore any things
 562 *    which are slightly inconvenient (such as locking conflicts between
 563 *    the page lock and the glock) and return having done no I/O. Its
 564 *    obviously not something we'd want to do on too regular a basis.
 565 *    Any I/O we ignore at this time will be done via readpage later.
 566 * 2. We don't handle stuffed files here we let readpage do the honours.
 567 * 3. mpage_readpages() does most of the heavy lifting in the common case.
 568 * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 569 */
 570
 571static int gfs2_readpages(struct file *file, struct address_space *mapping,
 572                          struct list_head *pages, unsigned nr_pages)
 573{
 574        struct inode *inode = mapping->host;
 575        struct gfs2_inode *ip = GFS2_I(inode);
 576        struct gfs2_sbd *sdp = GFS2_SB(inode);
 577        struct gfs2_holder gh;
 578        int ret;
 579
 580        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 581        ret = gfs2_glock_nq(&gh);
 582        if (unlikely(ret))
 583                goto out_uninit;
 584        if (!gfs2_is_stuffed(ip))
 585                ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
 586        gfs2_glock_dq(&gh);
 587out_uninit:
 588        gfs2_holder_uninit(&gh);
 589        if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 590                ret = -EIO;
 591        return ret;
 592}
 593
 594/**
 595 * gfs2_write_begin - Begin to write to a file
 596 * @file: The file to write to
 597 * @mapping: The mapping in which to write
 598 * @pos: The file offset at which to start writing
 599 * @len: Length of the write
 600 * @flags: Various flags
 601 * @pagep: Pointer to return the page
 602 * @fsdata: Pointer to return fs data (unused by GFS2)
 603 *
 604 * Returns: errno
 605 */
 606
 607static int gfs2_write_begin(struct file *file, struct address_space *mapping,
 608                            loff_t pos, unsigned len, unsigned flags,
 609                            struct page **pagep, void **fsdata)
 610{
 611        struct gfs2_inode *ip = GFS2_I(mapping->host);
 612        struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 613        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 614        unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
 615        int alloc_required;
 616        int error = 0;
 617        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 618        unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 619        struct page *page;
 620
 621        gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
 622        error = gfs2_glock_nq(&ip->i_gh);
 623        if (unlikely(error))
 624                goto out_uninit;
 625        if (&ip->i_inode == sdp->sd_rindex) {
 626                error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
 627                                           GL_NOCACHE, &m_ip->i_gh);
 628                if (unlikely(error)) {
 629                        gfs2_glock_dq(&ip->i_gh);
 630                        goto out_uninit;
 631                }
 632        }
 633
 634        alloc_required = gfs2_write_alloc_required(ip, pos, len);
 635
 636        if (alloc_required || gfs2_is_jdata(ip))
 637                gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
 638
 639        if (alloc_required) {
 640                error = gfs2_quota_lock_check(ip);
 641                if (error)
 642                        goto out_unlock;
 643
 644                error = gfs2_inplace_reserve(ip, data_blocks + ind_blocks);
 645                if (error)
 646                        goto out_qunlock;
 647        }
 648
 649        rblocks = RES_DINODE + ind_blocks;
 650        if (gfs2_is_jdata(ip))
 651                rblocks += data_blocks ? data_blocks : 1;
 652        if (ind_blocks || data_blocks)
 653                rblocks += RES_STATFS + RES_QUOTA;
 654        if (&ip->i_inode == sdp->sd_rindex)
 655                rblocks += 2 * RES_STATFS;
 656        if (alloc_required)
 657                rblocks += gfs2_rg_blocks(ip);
 658
 659        error = gfs2_trans_begin(sdp, rblocks,
 660                                 PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
 661        if (error)
 662                goto out_trans_fail;
 663
 664        error = -ENOMEM;
 665        flags |= AOP_FLAG_NOFS;
 666        page = grab_cache_page_write_begin(mapping, index, flags);
 667        *pagep = page;
 668        if (unlikely(!page))
 669                goto out_endtrans;
 670
 671        if (gfs2_is_stuffed(ip)) {
 672                error = 0;
 673                if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 674                        error = gfs2_unstuff_dinode(ip, page);
 675                        if (error == 0)
 676                                goto prepare_write;
 677                } else if (!PageUptodate(page)) {
 678                        error = stuffed_readpage(ip, page);
 679                }
 680                goto out;
 681        }
 682
 683prepare_write:
 684        error = __block_write_begin(page, from, len, gfs2_block_map);
 685out:
 686        if (error == 0)
 687                return 0;
 688
 689        unlock_page(page);
 690        page_cache_release(page);
 691
 692        gfs2_trans_end(sdp);
 693        if (pos + len > ip->i_inode.i_size)
 694                gfs2_trim_blocks(&ip->i_inode);
 695        goto out_trans_fail;
 696
 697out_endtrans:
 698        gfs2_trans_end(sdp);
 699out_trans_fail:
 700        if (alloc_required) {
 701                gfs2_inplace_release(ip);
 702out_qunlock:
 703                gfs2_quota_unlock(ip);
 704        }
 705out_unlock:
 706        if (&ip->i_inode == sdp->sd_rindex) {
 707                gfs2_glock_dq(&m_ip->i_gh);
 708                gfs2_holder_uninit(&m_ip->i_gh);
 709        }
 710        gfs2_glock_dq(&ip->i_gh);
 711out_uninit:
 712        gfs2_holder_uninit(&ip->i_gh);
 713        return error;
 714}
 715
 716/**
 717 * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 718 * @inode: the rindex inode
 719 */
 720static void adjust_fs_space(struct inode *inode)
 721{
 722        struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 723        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 724        struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 725        struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 726        struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 727        struct buffer_head *m_bh, *l_bh;
 728        u64 fs_total, new_free;
 729
 730        /* Total up the file system space, according to the latest rindex. */
 731        fs_total = gfs2_ri_total(sdp);
 732        if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
 733                return;
 734
 735        spin_lock(&sdp->sd_statfs_spin);
 736        gfs2_statfs_change_in(m_sc, m_bh->b_data +
 737                              sizeof(struct gfs2_dinode));
 738        if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 739                new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 740        else
 741                new_free = 0;
 742        spin_unlock(&sdp->sd_statfs_spin);
 743        fs_warn(sdp, "File system extended by %llu blocks.\n",
 744                (unsigned long long)new_free);
 745        gfs2_statfs_change(sdp, new_free, new_free, 0);
 746
 747        if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
 748                goto out;
 749        update_statfs(sdp, m_bh, l_bh);
 750        brelse(l_bh);
 751out:
 752        brelse(m_bh);
 753}
 754
 755/**
 756 * gfs2_stuffed_write_end - Write end for stuffed files
 757 * @inode: The inode
 758 * @dibh: The buffer_head containing the on-disk inode
 759 * @pos: The file position
 760 * @len: The length of the write
 761 * @copied: How much was actually copied by the VFS
 762 * @page: The page
 763 *
 764 * This copies the data from the page into the inode block after
 765 * the inode data structure itself.
 766 *
 767 * Returns: errno
 768 */
 769static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
 770                                  loff_t pos, unsigned len, unsigned copied,
 771                                  struct page *page)
 772{
 773        struct gfs2_inode *ip = GFS2_I(inode);
 774        struct gfs2_sbd *sdp = GFS2_SB(inode);
 775        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 776        u64 to = pos + copied;
 777        void *kaddr;
 778        unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
 779
 780        BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
 781        kaddr = kmap_atomic(page);
 782        memcpy(buf + pos, kaddr + pos, copied);
 783        memset(kaddr + pos + copied, 0, len - copied);
 784        flush_dcache_page(page);
 785        kunmap_atomic(kaddr);
 786
 787        if (!PageUptodate(page))
 788                SetPageUptodate(page);
 789        unlock_page(page);
 790        page_cache_release(page);
 791
 792        if (copied) {
 793                if (inode->i_size < to)
 794                        i_size_write(inode, to);
 795                mark_inode_dirty(inode);
 796        }
 797
 798        if (inode == sdp->sd_rindex) {
 799                adjust_fs_space(inode);
 800                sdp->sd_rindex_uptodate = 0;
 801        }
 802
 803        brelse(dibh);
 804        gfs2_trans_end(sdp);
 805        if (inode == sdp->sd_rindex) {
 806                gfs2_glock_dq(&m_ip->i_gh);
 807                gfs2_holder_uninit(&m_ip->i_gh);
 808        }
 809        gfs2_glock_dq(&ip->i_gh);
 810        gfs2_holder_uninit(&ip->i_gh);
 811        return copied;
 812}
 813
 814/**
 815 * gfs2_write_end
 816 * @file: The file to write to
 817 * @mapping: The address space to write to
 818 * @pos: The file position
 819 * @len: The length of the data
 820 * @copied:
 821 * @page: The page that has been written
 822 * @fsdata: The fsdata (unused in GFS2)
 823 *
 824 * The main write_end function for GFS2. We have a separate one for
 825 * stuffed files as they are slightly different, otherwise we just
 826 * put our locking around the VFS provided functions.
 827 *
 828 * Returns: errno
 829 */
 830
 831static int gfs2_write_end(struct file *file, struct address_space *mapping,
 832                          loff_t pos, unsigned len, unsigned copied,
 833                          struct page *page, void *fsdata)
 834{
 835        struct inode *inode = page->mapping->host;
 836        struct gfs2_inode *ip = GFS2_I(inode);
 837        struct gfs2_sbd *sdp = GFS2_SB(inode);
 838        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 839        struct buffer_head *dibh;
 840        unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
 841        unsigned int to = from + len;
 842        int ret;
 843
 844        BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
 845
 846        ret = gfs2_meta_inode_buffer(ip, &dibh);
 847        if (unlikely(ret)) {
 848                unlock_page(page);
 849                page_cache_release(page);
 850                goto failed;
 851        }
 852
 853        gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 854
 855        if (gfs2_is_stuffed(ip))
 856                return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
 857
 858        if (!gfs2_is_writeback(ip))
 859                gfs2_page_add_databufs(ip, page, from, to);
 860
 861        ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 862
 863        if (inode == sdp->sd_rindex) {
 864                adjust_fs_space(inode);
 865                sdp->sd_rindex_uptodate = 0;
 866        }
 867
 868        brelse(dibh);
 869failed:
 870        gfs2_trans_end(sdp);
 871        if (gfs2_mb_reserved(ip))
 872                gfs2_inplace_release(ip);
 873        if (ip->i_res->rs_qa_qd_num)
 874                gfs2_quota_unlock(ip);
 875        if (inode == sdp->sd_rindex) {
 876                gfs2_glock_dq(&m_ip->i_gh);
 877                gfs2_holder_uninit(&m_ip->i_gh);
 878        }
 879        gfs2_glock_dq(&ip->i_gh);
 880        gfs2_holder_uninit(&ip->i_gh);
 881        return ret;
 882}
 883
 884/**
 885 * gfs2_set_page_dirty - Page dirtying function
 886 * @page: The page to dirty
 887 *
 888 * Returns: 1 if it dirtyed the page, or 0 otherwise
 889 */
 890 
 891static int gfs2_set_page_dirty(struct page *page)
 892{
 893        SetPageChecked(page);
 894        return __set_page_dirty_buffers(page);
 895}
 896
 897/**
 898 * gfs2_bmap - Block map function
 899 * @mapping: Address space info
 900 * @lblock: The block to map
 901 *
 902 * Returns: The disk address for the block or 0 on hole or error
 903 */
 904
 905static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 906{
 907        struct gfs2_inode *ip = GFS2_I(mapping->host);
 908        struct gfs2_holder i_gh;
 909        sector_t dblock = 0;
 910        int error;
 911
 912        error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 913        if (error)
 914                return 0;
 915
 916        if (!gfs2_is_stuffed(ip))
 917                dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
 918
 919        gfs2_glock_dq_uninit(&i_gh);
 920
 921        return dblock;
 922}
 923
 924static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 925{
 926        struct gfs2_bufdata *bd;
 927
 928        lock_buffer(bh);
 929        gfs2_log_lock(sdp);
 930        clear_buffer_dirty(bh);
 931        bd = bh->b_private;
 932        if (bd) {
 933                if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
 934                        list_del_init(&bd->bd_list);
 935                else
 936                        gfs2_remove_from_journal(bh, current->journal_info, 0);
 937        }
 938        bh->b_bdev = NULL;
 939        clear_buffer_mapped(bh);
 940        clear_buffer_req(bh);
 941        clear_buffer_new(bh);
 942        gfs2_log_unlock(sdp);
 943        unlock_buffer(bh);
 944}
 945
 946static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 947{
 948        struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 949        struct buffer_head *bh, *head;
 950        unsigned long pos = 0;
 951
 952        BUG_ON(!PageLocked(page));
 953        if (offset == 0)
 954                ClearPageChecked(page);
 955        if (!page_has_buffers(page))
 956                goto out;
 957
 958        bh = head = page_buffers(page);
 959        do {
 960                if (offset <= pos)
 961                        gfs2_discard(sdp, bh);
 962                pos += bh->b_size;
 963                bh = bh->b_this_page;
 964        } while (bh != head);
 965out:
 966        if (offset == 0)
 967                try_to_release_page(page, 0);
 968}
 969
 970/**
 971 * gfs2_ok_for_dio - check that dio is valid on this file
 972 * @ip: The inode
 973 * @rw: READ or WRITE
 974 * @offset: The offset at which we are reading or writing
 975 *
 976 * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
 977 *          1 (to accept the i/o request)
 978 */
 979static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 980{
 981        /*
 982         * Should we return an error here? I can't see that O_DIRECT for
 983         * a stuffed file makes any sense. For now we'll silently fall
 984         * back to buffered I/O
 985         */
 986        if (gfs2_is_stuffed(ip))
 987                return 0;
 988
 989        if (offset >= i_size_read(&ip->i_inode))
 990                return 0;
 991        return 1;
 992}
 993
 994
 995
 996static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 997                              const struct iovec *iov, loff_t offset,
 998                              unsigned long nr_segs)
 999{
1000        struct file *file = iocb->ki_filp;
1001        struct inode *inode = file->f_mapping->host;
1002        struct gfs2_inode *ip = GFS2_I(inode);
1003        struct gfs2_holder gh;
1004        int rv;
1005
1006        /*
1007         * Deferred lock, even if its a write, since we do no allocation
1008         * on this path. All we need change is atime, and this lock mode
1009         * ensures that other nodes have flushed their buffered read caches
1010         * (i.e. their page cache entries for this inode). We do not,
1011         * unfortunately have the option of only flushing a range like
1012         * the VFS does.
1013         */
1014        gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1015        rv = gfs2_glock_nq(&gh);
1016        if (rv)
1017                return rv;
1018        rv = gfs2_ok_for_dio(ip, rw, offset);
1019        if (rv != 1)
1020                goto out; /* dio not valid, fall back to buffered i/o */
1021
1022        rv = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
1023                                  offset, nr_segs, gfs2_get_block_direct,
1024                                  NULL, NULL, 0);
1025out:
1026        gfs2_glock_dq_m(1, &gh);
1027        gfs2_holder_uninit(&gh);
1028        return rv;
1029}
1030
1031/**
1032 * gfs2_releasepage - free the metadata associated with a page
1033 * @page: the page that's being released
1034 * @gfp_mask: passed from Linux VFS, ignored by us
1035 *
1036 * Call try_to_free_buffers() if the buffers in this page can be
1037 * released.
1038 *
1039 * Returns: 0
1040 */
1041
1042int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1043{
1044        struct address_space *mapping = page->mapping;
1045        struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
1046        struct buffer_head *bh, *head;
1047        struct gfs2_bufdata *bd;
1048
1049        if (!page_has_buffers(page))
1050                return 0;
1051
1052        gfs2_log_lock(sdp);
1053        spin_lock(&sdp->sd_ail_lock);
1054        head = bh = page_buffers(page);
1055        do {
1056                if (atomic_read(&bh->b_count))
1057                        goto cannot_release;
1058                bd = bh->b_private;
1059                if (bd && bd->bd_ail)
1060                        goto cannot_release;
1061                if (buffer_pinned(bh) || buffer_dirty(bh))
1062                        goto not_possible;
1063                bh = bh->b_this_page;
1064        } while(bh != head);
1065        spin_unlock(&sdp->sd_ail_lock);
1066        gfs2_log_unlock(sdp);
1067
1068        head = bh = page_buffers(page);
1069        do {
1070                gfs2_log_lock(sdp);
1071                bd = bh->b_private;
1072                if (bd) {
1073                        gfs2_assert_warn(sdp, bd->bd_bh == bh);
1074                        if (!list_empty(&bd->bd_list)) {
1075                                if (!buffer_pinned(bh))
1076                                        list_del_init(&bd->bd_list);
1077                                else
1078                                        bd = NULL;
1079                        }
1080                        if (bd)
1081                                bd->bd_bh = NULL;
1082                        bh->b_private = NULL;
1083                }
1084                gfs2_log_unlock(sdp);
1085                if (bd)
1086                        kmem_cache_free(gfs2_bufdata_cachep, bd);
1087
1088                bh = bh->b_this_page;
1089        } while (bh != head);
1090
1091        return try_to_free_buffers(page);
1092
1093not_possible: /* Should never happen */
1094        WARN_ON(buffer_dirty(bh));
1095        WARN_ON(buffer_pinned(bh));
1096cannot_release:
1097        spin_unlock(&sdp->sd_ail_lock);
1098        gfs2_log_unlock(sdp);
1099        return 0;
1100}
1101
1102static const struct address_space_operations gfs2_writeback_aops = {
1103        .writepage = gfs2_writeback_writepage,
1104        .writepages = gfs2_writeback_writepages,
1105        .readpage = gfs2_readpage,
1106        .readpages = gfs2_readpages,
1107        .write_begin = gfs2_write_begin,
1108        .write_end = gfs2_write_end,
1109        .bmap = gfs2_bmap,
1110        .invalidatepage = gfs2_invalidatepage,
1111        .releasepage = gfs2_releasepage,
1112        .direct_IO = gfs2_direct_IO,
1113        .migratepage = buffer_migrate_page,
1114        .is_partially_uptodate = block_is_partially_uptodate,
1115        .error_remove_page = generic_error_remove_page,
1116};
1117
1118static const struct address_space_operations gfs2_ordered_aops = {
1119        .writepage = gfs2_ordered_writepage,
1120        .readpage = gfs2_readpage,
1121        .readpages = gfs2_readpages,
1122        .write_begin = gfs2_write_begin,
1123        .write_end = gfs2_write_end,
1124        .set_page_dirty = gfs2_set_page_dirty,
1125        .bmap = gfs2_bmap,
1126        .invalidatepage = gfs2_invalidatepage,
1127        .releasepage = gfs2_releasepage,
1128        .direct_IO = gfs2_direct_IO,
1129        .migratepage = buffer_migrate_page,
1130        .is_partially_uptodate = block_is_partially_uptodate,
1131        .error_remove_page = generic_error_remove_page,
1132};
1133
1134static const struct address_space_operations gfs2_jdata_aops = {
1135        .writepage = gfs2_jdata_writepage,
1136        .writepages = gfs2_jdata_writepages,
1137        .readpage = gfs2_readpage,
1138        .readpages = gfs2_readpages,
1139        .write_begin = gfs2_write_begin,
1140        .write_end = gfs2_write_end,
1141        .set_page_dirty = gfs2_set_page_dirty,
1142        .bmap = gfs2_bmap,
1143        .invalidatepage = gfs2_invalidatepage,
1144        .releasepage = gfs2_releasepage,
1145        .is_partially_uptodate = block_is_partially_uptodate,
1146        .error_remove_page = generic_error_remove_page,
1147};
1148
1149void gfs2_set_aops(struct inode *inode)
1150{
1151        struct gfs2_inode *ip = GFS2_I(inode);
1152
1153        if (gfs2_is_writeback(ip))
1154                inode->i_mapping->a_ops = &gfs2_writeback_aops;
1155        else if (gfs2_is_ordered(ip))
1156                inode->i_mapping->a_ops = &gfs2_ordered_aops;
1157        else if (gfs2_is_jdata(ip))
1158                inode->i_mapping->a_ops = &gfs2_jdata_aops;
1159        else
1160                BUG();
1161}
1162
1163
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