fs/gfs2/aops.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   4  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   5  */
   6
   7 #include <linux/sched.h>
   8 #include <linux/slab.h>
   9 #include <linux/spinlock.h>
  10 #include <linux/completion.h>
  11 #include <linux/buffer_head.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/pagevec.h>
  14 #include <linux/mpage.h>
  15 #include <linux/fs.h>
  16 #include <linux/writeback.h>
  17 #include <linux/swap.h>
  18 #include <linux/gfs2_ondisk.h>
  19 #include <linux/backing-dev.h>
  20 #include <linux/uio.h>
  21 #include <trace/events/writeback.h>
  22 #include <linux/sched/signal.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 #include "aops.h"
  38
  39
  40 void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  41                             unsigned int from, unsigned int len)
  42 {
  43         struct buffer_head *head = page_buffers(page);
  44         unsigned int bsize = head->b_size;
  45         struct buffer_head *bh;
  46         unsigned int to = from + len;
  47         unsigned int start, end;
  48
  49         for (bh = head, start = 0; bh != head || !start;
  50              bh = bh->b_this_page, start = end) {
  51                 end = start + bsize;
  52                 if (end <= from)
  53                         continue;
  54                 if (start >= to)
  55                         break;
  56                 set_buffer_uptodate(bh);
  57                 gfs2_trans_add_data(ip->i_gl, bh);
  58         }
  59 }
  60
  61 /**
  62  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  63  * @inode: The inode
  64  * @lblock: The block number to look up
  65  * @bh_result: The buffer head to return the result in
  66  * @create: Non-zero if we may add block to the file
  67  *
  68  * Returns: errno
  69  */
  70
  71 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  72                                   struct buffer_head *bh_result, int create)
  73 {
  74         int error;
  75
  76         error = gfs2_block_map(inode, lblock, bh_result, 0);
  77         if (error)
  78                 return error;
  79         if (!buffer_mapped(bh_result))
  80                 return -EIO;
  81         return 0;
  82 }
  83
  84 /**
  85  * gfs2_writepage - Write page for writeback mappings
  86  * @page: The page
  87  * @wbc: The writeback control
  88  */
  89 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
  90 {
  91         struct inode *inode = page->mapping->host;
  92         struct gfs2_inode *ip = GFS2_I(inode);
  93         struct gfs2_sbd *sdp = GFS2_SB(inode);
  94         loff_t i_size = i_size_read(inode);
  95         pgoff_t end_index = i_size >> PAGE_SHIFT;
  96         unsigned offset;
  97
  98         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
  99                 goto out;
 100         if (current->journal_info)
 101                 goto redirty;
 102         /* Is the page fully outside i_size? (truncate in progress) */
 103         offset = i_size & (PAGE_SIZE-1);
 104         if (page->index > end_index || (page->index == end_index && !offset)) {
 105                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
 106                 goto out;
 107         }
 108
 109         return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
 110
 111 redirty:
 112         redirty_page_for_writepage(wbc, page);
 113 out:
 114         unlock_page(page);
 115         return 0;
 116 }
 117
 118 /* This is the same as calling block_write_full_page, but it also
 119  * writes pages outside of i_size
 120  */
 121 static int gfs2_write_full_page(struct page *page, get_block_t *get_block,
 122                                 struct writeback_control *wbc)
 123 {
 124         struct inode * const inode = page->mapping->host;
 125         loff_t i_size = i_size_read(inode);
 126         const pgoff_t end_index = i_size >> PAGE_SHIFT;
 127         unsigned offset;
 128
 129         /*
 130          * The page straddles i_size.  It must be zeroed out on each and every
 131          * writepage invocation because it may be mmapped.  "A file is mapped
 132          * in multiples of the page size.  For a file that is not a multiple of
 133          * the  page size, the remaining memory is zeroed when mapped, and
 134          * writes to that region are not written out to the file."
 135          */
 136         offset = i_size & (PAGE_SIZE - 1);
 137         if (page->index == end_index && offset)
 138                 zero_user_segment(page, offset, PAGE_SIZE);
 139
 140         return __block_write_full_page(inode, page, get_block, wbc,
 141                                        end_buffer_async_write);
 142 }
 143
 144 /**
 145  * __gfs2_jdata_writepage - The core of jdata writepage
 146  * @page: The page to write
 147  * @wbc: The writeback control
 148  *
 149  * This is shared between writepage and writepages and implements the
 150  * core of the writepage operation. If a transaction is required then
 151  * PageChecked will have been set and the transaction will have
 152  * already been started before this is called.
 153  */
 154
 155 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 156 {
 157         struct inode *inode = page->mapping->host;
 158         struct gfs2_inode *ip = GFS2_I(inode);
 159         struct gfs2_sbd *sdp = GFS2_SB(inode);
 160
 161         if (PageChecked(page)) {
 162                 ClearPageChecked(page);
 163                 if (!page_has_buffers(page)) {
 164                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 165                                              BIT(BH_Dirty)|BIT(BH_Uptodate));
 166                 }
 167                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize);
 168         }
 169         return gfs2_write_full_page(page, gfs2_get_block_noalloc, wbc);
 170 }
 171
 172 /**
 173  * gfs2_jdata_writepage - Write complete page
 174  * @page: Page to write
 175  * @wbc: The writeback control
 176  *
 177  * Returns: errno
 178  *
 179  */
 180
 181 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 182 {
 183         struct inode *inode = page->mapping->host;
 184         struct gfs2_inode *ip = GFS2_I(inode);
 185         struct gfs2_sbd *sdp = GFS2_SB(inode);
 186
 187         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 188                 goto out;
 189         if (PageChecked(page) || current->journal_info)
 190                 goto out_ignore;
 191         return __gfs2_jdata_writepage(page, wbc);
 192
 193 out_ignore:
 194         redirty_page_for_writepage(wbc, page);
 195 out:
 196         unlock_page(page);
 197         return 0;
 198 }
 199
 200 /**
 201  * gfs2_writepages - Write a bunch of dirty pages back to disk
 202  * @mapping: The mapping to write
 203  * @wbc: Write-back control
 204  *
 205  * Used for both ordered and writeback modes.
 206  */
 207 static int gfs2_writepages(struct address_space *mapping,
 208                            struct writeback_control *wbc)
 209 {
 210         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 211         int ret = mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 212
 213         /*
 214          * Even if we didn't write any pages here, we might still be holding
 215          * dirty pages in the ail. We forcibly flush the ail because we don't
 216          * want balance_dirty_pages() to loop indefinitely trying to write out
 217          * pages held in the ail that it can't find.
 218          */
 219         if (ret == 0)
 220                 set_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
 221
 222         return ret;
 223 }
 224
 225 /**
 226  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 227  * @mapping: The mapping
 228  * @wbc: The writeback control
 229  * @pvec: The vector of pages
 230  * @nr_pages: The number of pages to write
 231  * @done_index: Page index
 232  *
 233  * Returns: non-zero if loop should terminate, zero otherwise
 234  */
 235
 236 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 237                                     struct writeback_control *wbc,
 238                                     struct pagevec *pvec,
 239                                     int nr_pages,
 240                                     pgoff_t *done_index)
 241 {
 242         struct inode *inode = mapping->host;
 243         struct gfs2_sbd *sdp = GFS2_SB(inode);
 244         unsigned nrblocks = nr_pages * (PAGE_SIZE >> inode->i_blkbits);
 245         int i;
 246         int ret;
 247
 248         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 249         if (ret < 0)
 250                 return ret;
 251
 252         for(i = 0; i < nr_pages; i++) {
 253                 struct page *page = pvec->pages[i];
 254
 255                 *done_index = page->index;
 256
 257                 lock_page(page);
 258
 259                 if (unlikely(page->mapping != mapping)) {
 260 continue_unlock:
 261                         unlock_page(page);
 262                         continue;
 263                 }
 264
 265                 if (!PageDirty(page)) {
 266                         /* someone wrote it for us */
 267                         goto continue_unlock;
 268                 }
 269
 270                 if (PageWriteback(page)) {
 271                         if (wbc->sync_mode != WB_SYNC_NONE)
 272                                 wait_on_page_writeback(page);
 273                         else
 274                                 goto continue_unlock;
 275                 }
 276
 277                 BUG_ON(PageWriteback(page));
 278                 if (!clear_page_dirty_for_io(page))
 279                         goto continue_unlock;
 280
 281                 trace_wbc_writepage(wbc, inode_to_bdi(inode));
 282
 283                 ret = __gfs2_jdata_writepage(page, wbc);
 284                 if (unlikely(ret)) {
 285                         if (ret == AOP_WRITEPAGE_ACTIVATE) {
 286                                 unlock_page(page);
 287                                 ret = 0;
 288                         } else {
 289
 290                                 /*
 291                                  * done_index is set past this page,
 292                                  * so media errors will not choke
 293                                  * background writeout for the entire
 294                                  * file. This has consequences for
 295                                  * range_cyclic semantics (ie. it may
 296                                  * not be suitable for data integrity
 297                                  * writeout).
 298                                  */
 299                                 *done_index = page->index + 1;
 300                                 ret = 1;
 301                                 break;
 302                         }
 303                 }
 304
 305                 /*
 306                  * We stop writing back only if we are not doing
 307                  * integrity sync. In case of integrity sync we have to
 308                  * keep going until we have written all the pages
 309                  * we tagged for writeback prior to entering this loop.
 310                  */
 311                 if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
 312                         ret = 1;
 313                         break;
 314                 }
 315
 316         }
 317         gfs2_trans_end(sdp);
 318         return ret;
 319 }
 320
 321 /**
 322  * gfs2_write_cache_jdata - Like write_cache_pages but different
 323  * @mapping: The mapping to write
 324  * @wbc: The writeback control
 325  *
 326  * The reason that we use our own function here is that we need to
 327  * start transactions before we grab page locks. This allows us
 328  * to get the ordering right.
 329  */
 330
 331 static int gfs2_write_cache_jdata(struct address_space *mapping,
 332                                   struct writeback_control *wbc)
 333 {
 334         int ret = 0;
 335         int done = 0;
 336         struct pagevec pvec;
 337         int nr_pages;
 338         pgoff_t uninitialized_var(writeback_index);
 339         pgoff_t index;
 340         pgoff_t end;
 341         pgoff_t done_index;
 342         int cycled;
 343         int range_whole = 0;
 344         xa_mark_t tag;
 345
 346         pagevec_init(&pvec);
 347         if (wbc->range_cyclic) {
 348                 writeback_index = mapping->writeback_index; /* prev offset */
 349                 index = writeback_index;
 350                 if (index == 0)
 351                         cycled = 1;
 352                 else
 353                         cycled = 0;
 354                 end = -1;
 355         } else {
 356                 index = wbc->range_start >> PAGE_SHIFT;
 357                 end = wbc->range_end >> PAGE_SHIFT;
 358                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 359                         range_whole = 1;
 360                 cycled = 1; /* ignore range_cyclic tests */
 361         }
 362         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 363                 tag = PAGECACHE_TAG_TOWRITE;
 364         else
 365                 tag = PAGECACHE_TAG_DIRTY;
 366
 367 retry:
 368         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 369                 tag_pages_for_writeback(mapping, index, end);
 370         done_index = index;
 371         while (!done && (index <= end)) {
 372                 nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
 373                                 tag);
 374                 if (nr_pages == 0)
 375                         break;
 376
 377                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, &done_index);
 378                 if (ret)
 379                         done = 1;
 380                 if (ret > 0)
 381                         ret = 0;
 382                 pagevec_release(&pvec);
 383                 cond_resched();
 384         }
 385
 386         if (!cycled && !done) {
 387                 /*
 388                  * range_cyclic:
 389                  * We hit the last page and there is more work to be done: wrap
 390                  * back to the start of the file
 391                  */
 392                 cycled = 1;
 393                 index = 0;
 394                 end = writeback_index - 1;
 395                 goto retry;
 396         }
 397
 398         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 399                 mapping->writeback_index = done_index;
 400
 401         return ret;
 402 }
 403
 404
 405 /**
 406  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 407  * @mapping: The mapping to write
 408  * @wbc: The writeback control
 409  *
 410  */
 411
 412 static int gfs2_jdata_writepages(struct address_space *mapping,
 413                                  struct writeback_control *wbc)
 414 {
 415         struct gfs2_inode *ip = GFS2_I(mapping->host);
 416         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 417         int ret;
 418
 419         ret = gfs2_write_cache_jdata(mapping, wbc);
 420         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 421                 gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
 422                                GFS2_LFC_JDATA_WPAGES);
 423                 ret = gfs2_write_cache_jdata(mapping, wbc);
 424         }
 425         return ret;
 426 }
 427
 428 /**
 429  * stuffed_readpage - Fill in a Linux page with stuffed file data
 430  * @ip: the inode
 431  * @page: the page
 432  *
 433  * Returns: errno
 434  */
 435 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 436 {
 437         struct buffer_head *dibh;
 438         u64 dsize = i_size_read(&ip->i_inode);
 439         void *kaddr;
 440         int error;
 441
 442         /*
 443          * Due to the order of unstuffing files and ->fault(), we can be
 444          * asked for a zero page in the case of a stuffed file being extended,
 445          * so we need to supply one here. It doesn't happen often.
 446          */
 447         if (unlikely(page->index)) {
 448                 zero_user(page, 0, PAGE_SIZE);
 449                 SetPageUptodate(page);
 450                 return 0;
 451         }
 452
 453         error = gfs2_meta_inode_buffer(ip, &dibh);
 454         if (error)
 455                 return error;
 456
 457         kaddr = kmap_atomic(page);
 458         if (dsize > gfs2_max_stuffed_size(ip))
 459                 dsize = gfs2_max_stuffed_size(ip);
 460         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 461         memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
 462         kunmap_atomic(kaddr);
 463         flush_dcache_page(page);
 464         brelse(dibh);
 465         SetPageUptodate(page);
 466
 467         return 0;
 468 }
 469
 470
 471 static int __gfs2_readpage(void *file, struct page *page)
 472 {
 473         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 474         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 475         int error;
 476
 477         if (i_blocksize(page->mapping->host) == PAGE_SIZE &&
 478             !page_has_buffers(page)) {
 479                 error = iomap_readpage(page, &gfs2_iomap_ops);
 480         } else if (gfs2_is_stuffed(ip)) {
 481                 error = stuffed_readpage(ip, page);
 482                 unlock_page(page);
 483         } else {
 484                 error = mpage_readpage(page, gfs2_block_map);
 485         }
 486
 487         if (unlikely(gfs2_withdrawn(sdp)))
 488                 return -EIO;
 489
 490         return error;
 491 }
 492
 493 /**
 494  * gfs2_readpage - read a page of a file
 495  * @file: The file to read
 496  * @page: The page of the file
 497  */
 498
 499 static int gfs2_readpage(struct file *file, struct page *page)
 500 {
 501         return __gfs2_readpage(file, page);
 502 }
 503
 504 /**
 505  * gfs2_internal_read - read an internal file
 506  * @ip: The gfs2 inode
 507  * @buf: The buffer to fill
 508  * @pos: The file position
 509  * @size: The amount to read
 510  *
 511  */
 512
 513 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
 514                        unsigned size)
 515 {
 516         struct address_space *mapping = ip->i_inode.i_mapping;
 517         unsigned long index = *pos >> PAGE_SHIFT;
 518         unsigned offset = *pos & (PAGE_SIZE - 1);
 519         unsigned copied = 0;
 520         unsigned amt;
 521         struct page *page;
 522         void *p;
 523
 524         do {
 525                 amt = size - copied;
 526                 if (offset + size > PAGE_SIZE)
 527                         amt = PAGE_SIZE - offset;
 528                 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
 529                 if (IS_ERR(page))
 530                         return PTR_ERR(page);
 531                 p = kmap_atomic(page);
 532                 memcpy(buf + copied, p + offset, amt);
 533                 kunmap_atomic(p);
 534                 put_page(page);
 535                 copied += amt;
 536                 index++;
 537                 offset = 0;
 538         } while(copied < size);
 539         (*pos) += size;
 540         return size;
 541 }
 542
 543 /**
 544  * gfs2_readahead - Read a bunch of pages at once
 545  * @file: The file to read from
 546  * @mapping: Address space info
 547  * @pages: List of pages to read
 548  * @nr_pages: Number of pages to read
 549  *
 550  * Some notes:
 551  * 1. This is only for readahead, so we can simply ignore any things
 552  *    which are slightly inconvenient (such as locking conflicts between
 553  *    the page lock and the glock) and return having done no I/O. Its
 554  *    obviously not something we'd want to do on too regular a basis.
 555  *    Any I/O we ignore at this time will be done via readpage later.
 556  * 2. We don't handle stuffed files here we let readpage do the honours.
 557  * 3. mpage_readahead() does most of the heavy lifting in the common case.
 558  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 559  */
 560
 561 static void gfs2_readahead(struct readahead_control *rac)
 562 {
 563         struct inode *inode = rac->mapping->host;
 564         struct gfs2_inode *ip = GFS2_I(inode);
 565
 566         if (!gfs2_is_stuffed(ip))
 567                 mpage_readahead(rac, gfs2_block_map);
 568 }
 569
 570 /**
 571  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 572  * @inode: the rindex inode
 573  */
 574 void adjust_fs_space(struct inode *inode)
 575 {
 576         struct gfs2_sbd *sdp = GFS2_SB(inode);
 577         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 578         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 579         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 580         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 581         struct buffer_head *m_bh, *l_bh;
 582         u64 fs_total, new_free;
 583
 584         if (gfs2_trans_begin(sdp, 2 * RES_STATFS, 0) != 0)
 585                 return;
 586
 587         /* Total up the file system space, according to the latest rindex. */
 588         fs_total = gfs2_ri_total(sdp);
 589         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
 590                 goto out;
 591
 592         spin_lock(&sdp->sd_statfs_spin);
 593         gfs2_statfs_change_in(m_sc, m_bh->b_data +
 594                               sizeof(struct gfs2_dinode));
 595         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 596                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 597         else
 598                 new_free = 0;
 599         spin_unlock(&sdp->sd_statfs_spin);
 600         fs_warn(sdp, "File system extended by %llu blocks.\n",
 601                 (unsigned long long)new_free);
 602         gfs2_statfs_change(sdp, new_free, new_free, 0);
 603
 604         if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
 605                 goto out2;
 606         update_statfs(sdp, m_bh, l_bh);
 607         brelse(l_bh);
 608 out2:
 609         brelse(m_bh);
 610 out:
 611         sdp->sd_rindex_uptodate = 0;
 612         gfs2_trans_end(sdp);
 613 }
 614
 615 /**
 616  * jdata_set_page_dirty - Page dirtying function
 617  * @page: The page to dirty
 618  *
 619  * Returns: 1 if it dirtyed the page, or 0 otherwise
 620  */
 621
 622 static int jdata_set_page_dirty(struct page *page)
 623 {
 624         SetPageChecked(page);
 625         return __set_page_dirty_buffers(page);
 626 }
 627
 628 /**
 629  * gfs2_bmap - Block map function
 630  * @mapping: Address space info
 631  * @lblock: The block to map
 632  *
 633  * Returns: The disk address for the block or 0 on hole or error
 634  */
 635
 636 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 637 {
 638         struct gfs2_inode *ip = GFS2_I(mapping->host);
 639         struct gfs2_holder i_gh;
 640         sector_t dblock = 0;
 641         int error;
 642
 643         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 644         if (error)
 645                 return 0;
 646
 647         if (!gfs2_is_stuffed(ip))
 648                 dblock = iomap_bmap(mapping, lblock, &gfs2_iomap_ops);
 649
 650         gfs2_glock_dq_uninit(&i_gh);
 651
 652         return dblock;
 653 }
 654
 655 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 656 {
 657         struct gfs2_bufdata *bd;
 658
 659         lock_buffer(bh);
 660         gfs2_log_lock(sdp);
 661         clear_buffer_dirty(bh);
 662         bd = bh->b_private;
 663         if (bd) {
 664                 if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
 665                         list_del_init(&bd->bd_list);
 666                 else
 667                         gfs2_remove_from_journal(bh, REMOVE_JDATA);
 668         }
 669         bh->b_bdev = NULL;
 670         clear_buffer_mapped(bh);
 671         clear_buffer_req(bh);
 672         clear_buffer_new(bh);
 673         gfs2_log_unlock(sdp);
 674         unlock_buffer(bh);
 675 }
 676
 677 static void gfs2_invalidatepage(struct page *page, unsigned int offset,
 678                                 unsigned int length)
 679 {
 680         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 681         unsigned int stop = offset + length;
 682         int partial_page = (offset || length < PAGE_SIZE);
 683         struct buffer_head *bh, *head;
 684         unsigned long pos = 0;
 685
 686         BUG_ON(!PageLocked(page));
 687         if (!partial_page)
 688                 ClearPageChecked(page);
 689         if (!page_has_buffers(page))
 690                 goto out;
 691
 692         bh = head = page_buffers(page);
 693         do {
 694                 if (pos + bh->b_size > stop)
 695                         return;
 696
 697                 if (offset <= pos)
 698                         gfs2_discard(sdp, bh);
 699                 pos += bh->b_size;
 700                 bh = bh->b_this_page;
 701         } while (bh != head);
 702 out:
 703         if (!partial_page)
 704                 try_to_release_page(page, 0);
 705 }
 706
 707 /**
 708  * gfs2_releasepage - free the metadata associated with a page
 709  * @page: the page that's being released
 710  * @gfp_mask: passed from Linux VFS, ignored by us
 711  *
 712  * Calls try_to_free_buffers() to free the buffers and put the page if the
 713  * buffers can be released.
 714  *
 715  * Returns: 1 if the page was put or else 0
 716  */
 717
 718 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 719 {
 720         struct address_space *mapping = page->mapping;
 721         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 722         struct buffer_head *bh, *head;
 723         struct gfs2_bufdata *bd;
 724
 725         if (!page_has_buffers(page))
 726                 return 0;
 727
 728         /*
 729          * From xfs_vm_releasepage: mm accommodates an old ext3 case where
 730          * clean pages might not have had the dirty bit cleared.  Thus, it can
 731          * send actual dirty pages to ->releasepage() via shrink_active_list().
 732          *
 733          * As a workaround, we skip pages that contain dirty buffers below.
 734          * Once ->releasepage isn't called on dirty pages anymore, we can warn
 735          * on dirty buffers like we used to here again.
 736          */
 737
 738         gfs2_log_lock(sdp);
 739         spin_lock(&sdp->sd_ail_lock);
 740         head = bh = page_buffers(page);
 741         do {
 742                 if (atomic_read(&bh->b_count))
 743                         goto cannot_release;
 744                 bd = bh->b_private;
 745                 if (bd && bd->bd_tr)
 746                         goto cannot_release;
 747                 if (buffer_dirty(bh) || WARN_ON(buffer_pinned(bh)))
 748                         goto cannot_release;
 749                 bh = bh->b_this_page;
 750         } while(bh != head);
 751         spin_unlock(&sdp->sd_ail_lock);
 752
 753         head = bh = page_buffers(page);
 754         do {
 755                 bd = bh->b_private;
 756                 if (bd) {
 757                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 758                         bd->bd_bh = NULL;
 759                         bh->b_private = NULL;
 760                         /*
 761                          * The bd may still be queued as a revoke, in which
 762                          * case we must not dequeue nor free it.
 763                          */
 764                         if (!bd->bd_blkno && !list_empty(&bd->bd_list))
 765                                 list_del_init(&bd->bd_list);
 766                         if (list_empty(&bd->bd_list))
 767                                 kmem_cache_free(gfs2_bufdata_cachep, bd);
 768                 }
 769
 770                 bh = bh->b_this_page;
 771         } while (bh != head);
 772         gfs2_log_unlock(sdp);
 773
 774         return try_to_free_buffers(page);
 775
 776 cannot_release:
 777         spin_unlock(&sdp->sd_ail_lock);
 778         gfs2_log_unlock(sdp);
 779         return 0;
 780 }
 781
 782 static const struct address_space_operations gfs2_aops = {
 783         .writepage = gfs2_writepage,
 784         .writepages = gfs2_writepages,
 785         .readpage = gfs2_readpage,
 786         .readahead = gfs2_readahead,
 787         .bmap = gfs2_bmap,
 788         .invalidatepage = gfs2_invalidatepage,
 789         .releasepage = gfs2_releasepage,
 790         .direct_IO = noop_direct_IO,
 791         .migratepage = buffer_migrate_page,
 792         .is_partially_uptodate = block_is_partially_uptodate,
 793         .error_remove_page = generic_error_remove_page,
 794 };
 795
 796 static const struct address_space_operations gfs2_jdata_aops = {
 797         .writepage = gfs2_jdata_writepage,
 798         .writepages = gfs2_jdata_writepages,
 799         .readpage = gfs2_readpage,
 800         .readahead = gfs2_readahead,
 801         .set_page_dirty = jdata_set_page_dirty,
 802         .bmap = gfs2_bmap,
 803         .invalidatepage = gfs2_invalidatepage,
 804         .releasepage = gfs2_releasepage,
 805         .is_partially_uptodate = block_is_partially_uptodate,
 806         .error_remove_page = generic_error_remove_page,
 807 };
 808
 809 void gfs2_set_aops(struct inode *inode)
 810 {
 811         if (gfs2_is_jdata(GFS2_I(inode)))
 812                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
 813         else
 814                 inode->i_mapping->a_ops = &gfs2_aops;
 815 }