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 -ENODATA;
  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         struct iomap_writepage_ctx wpc = { };
  95
  96         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
  97                 goto out;
  98         if (current->journal_info)
  99                 goto redirty;
 100         return iomap_writepage(page, wbc, &wpc, &gfs2_writeback_ops);
 101
 102 redirty:
 103         redirty_page_for_writepage(wbc, page);
 104 out:
 105         unlock_page(page);
 106         return 0;
 107 }
 108
 109 /**
 110  * gfs2_write_jdata_page - gfs2 jdata-specific version of block_write_full_page
 111  * @page: The page to write
 112  * @wbc: The writeback control
 113  *
 114  * This is the same as calling block_write_full_page, but it also
 115  * writes pages outside of i_size
 116  */
 117 static int gfs2_write_jdata_page(struct page *page,
 118                                  struct writeback_control *wbc)
 119 {
 120         struct inode * const inode = page->mapping->host;
 121         loff_t i_size = i_size_read(inode);
 122         const pgoff_t end_index = i_size >> PAGE_SHIFT;
 123         unsigned offset;
 124
 125         /*
 126          * The page straddles i_size.  It must be zeroed out on each and every
 127          * writepage invocation because it may be mmapped.  "A file is mapped
 128          * in multiples of the page size.  For a file that is not a multiple of
 129          * the  page size, the remaining memory is zeroed when mapped, and
 130          * writes to that region are not written out to the file."
 131          */
 132         offset = i_size & (PAGE_SIZE - 1);
 133         if (page->index == end_index && offset)
 134                 zero_user_segment(page, offset, PAGE_SIZE);
 135
 136         return __block_write_full_page(inode, page, gfs2_get_block_noalloc, wbc,
 137                                        end_buffer_async_write);
 138 }
 139
 140 /**
 141  * __gfs2_jdata_writepage - The core of jdata writepage
 142  * @page: The page to write
 143  * @wbc: The writeback control
 144  *
 145  * This is shared between writepage and writepages and implements the
 146  * core of the writepage operation. If a transaction is required then
 147  * PageChecked will have been set and the transaction will have
 148  * already been started before this is called.
 149  */
 150
 151 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 152 {
 153         struct inode *inode = page->mapping->host;
 154         struct gfs2_inode *ip = GFS2_I(inode);
 155
 156         if (PageChecked(page)) {
 157                 ClearPageChecked(page);
 158                 if (!page_has_buffers(page)) {
 159                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 160                                              BIT(BH_Dirty)|BIT(BH_Uptodate));
 161                 }
 162                 gfs2_page_add_databufs(ip, page, 0, PAGE_SIZE);
 163         }
 164         return gfs2_write_jdata_page(page, wbc);
 165 }
 166
 167 /**
 168  * gfs2_jdata_writepage - Write complete page
 169  * @page: Page to write
 170  * @wbc: The writeback control
 171  *
 172  * Returns: errno
 173  *
 174  */
 175
 176 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 177 {
 178         struct inode *inode = page->mapping->host;
 179         struct gfs2_inode *ip = GFS2_I(inode);
 180         struct gfs2_sbd *sdp = GFS2_SB(inode);
 181
 182         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 183                 goto out;
 184         if (PageChecked(page) || current->journal_info)
 185                 goto out_ignore;
 186         return __gfs2_jdata_writepage(page, wbc);
 187
 188 out_ignore:
 189         redirty_page_for_writepage(wbc, page);
 190 out:
 191         unlock_page(page);
 192         return 0;
 193 }
 194
 195 /**
 196  * gfs2_writepages - Write a bunch of dirty pages back to disk
 197  * @mapping: The mapping to write
 198  * @wbc: Write-back control
 199  *
 200  * Used for both ordered and writeback modes.
 201  */
 202 static int gfs2_writepages(struct address_space *mapping,
 203                            struct writeback_control *wbc)
 204 {
 205         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 206         struct iomap_writepage_ctx wpc = { };
 207         int ret;
 208
 209         /*
 210          * Even if we didn't write any pages here, we might still be holding
 211          * dirty pages in the ail. We forcibly flush the ail because we don't
 212          * want balance_dirty_pages() to loop indefinitely trying to write out
 213          * pages held in the ail that it can't find.
 214          */
 215         ret = iomap_writepages(mapping, wbc, &wpc, &gfs2_writeback_ops);
 216         if (ret == 0)
 217                 set_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
 218         return ret;
 219 }
 220
 221 /**
 222  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 223  * @mapping: The mapping
 224  * @wbc: The writeback control
 225  * @pvec: The vector of pages
 226  * @nr_pages: The number of pages to write
 227  * @done_index: Page index
 228  *
 229  * Returns: non-zero if loop should terminate, zero otherwise
 230  */
 231
 232 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 233                                     struct writeback_control *wbc,
 234                                     struct pagevec *pvec,
 235                                     int nr_pages,
 236                                     pgoff_t *done_index)
 237 {
 238         struct inode *inode = mapping->host;
 239         struct gfs2_sbd *sdp = GFS2_SB(inode);
 240         unsigned nrblocks = nr_pages * (PAGE_SIZE >> inode->i_blkbits);
 241         int i;
 242         int ret;
 243
 244         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 245         if (ret < 0)
 246                 return ret;
 247
 248         for(i = 0; i < nr_pages; i++) {
 249                 struct page *page = pvec->pages[i];
 250
 251                 *done_index = page->index;
 252
 253                 lock_page(page);
 254
 255                 if (unlikely(page->mapping != mapping)) {
 256 continue_unlock:
 257                         unlock_page(page);
 258                         continue;
 259                 }
 260
 261                 if (!PageDirty(page)) {
 262                         /* someone wrote it for us */
 263                         goto continue_unlock;
 264                 }
 265
 266                 if (PageWriteback(page)) {
 267                         if (wbc->sync_mode != WB_SYNC_NONE)
 268                                 wait_on_page_writeback(page);
 269                         else
 270                                 goto continue_unlock;
 271                 }
 272
 273                 BUG_ON(PageWriteback(page));
 274                 if (!clear_page_dirty_for_io(page))
 275                         goto continue_unlock;
 276
 277                 trace_wbc_writepage(wbc, inode_to_bdi(inode));
 278
 279                 ret = __gfs2_jdata_writepage(page, wbc);
 280                 if (unlikely(ret)) {
 281                         if (ret == AOP_WRITEPAGE_ACTIVATE) {
 282                                 unlock_page(page);
 283                                 ret = 0;
 284                         } else {
 285
 286                                 /*
 287                                  * done_index is set past this page,
 288                                  * so media errors will not choke
 289                                  * background writeout for the entire
 290                                  * file. This has consequences for
 291                                  * range_cyclic semantics (ie. it may
 292                                  * not be suitable for data integrity
 293                                  * writeout).
 294                                  */
 295                                 *done_index = page->index + 1;
 296                                 ret = 1;
 297                                 break;
 298                         }
 299                 }
 300
 301                 /*
 302                  * We stop writing back only if we are not doing
 303                  * integrity sync. In case of integrity sync we have to
 304                  * keep going until we have written all the pages
 305                  * we tagged for writeback prior to entering this loop.
 306                  */
 307                 if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
 308                         ret = 1;
 309                         break;
 310                 }
 311
 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  *
 322  * The reason that we use our own function here is that we need to
 323  * start transactions before we grab page locks. This allows us
 324  * to get the ordering right.
 325  */
 326
 327 static int gfs2_write_cache_jdata(struct address_space *mapping,
 328                                   struct writeback_control *wbc)
 329 {
 330         int ret = 0;
 331         int done = 0;
 332         struct pagevec pvec;
 333         int nr_pages;
 334         pgoff_t writeback_index;
 335         pgoff_t index;
 336         pgoff_t end;
 337         pgoff_t done_index;
 338         int cycled;
 339         int range_whole = 0;
 340         xa_mark_t tag;
 341
 342         pagevec_init(&pvec);
 343         if (wbc->range_cyclic) {
 344                 writeback_index = mapping->writeback_index; /* prev offset */
 345                 index = writeback_index;
 346                 if (index == 0)
 347                         cycled = 1;
 348                 else
 349                         cycled = 0;
 350                 end = -1;
 351         } else {
 352                 index = wbc->range_start >> PAGE_SHIFT;
 353                 end = wbc->range_end >> PAGE_SHIFT;
 354                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 355                         range_whole = 1;
 356                 cycled = 1; /* ignore range_cyclic tests */
 357         }
 358         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 359                 tag = PAGECACHE_TAG_TOWRITE;
 360         else
 361                 tag = PAGECACHE_TAG_DIRTY;
 362
 363 retry:
 364         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 365                 tag_pages_for_writeback(mapping, index, end);
 366         done_index = index;
 367         while (!done && (index <= end)) {
 368                 nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
 369                                 tag);
 370                 if (nr_pages == 0)
 371                         break;
 372
 373                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, &done_index);
 374                 if (ret)
 375                         done = 1;
 376                 if (ret > 0)
 377                         ret = 0;
 378                 pagevec_release(&pvec);
 379                 cond_resched();
 380         }
 381
 382         if (!cycled && !done) {
 383                 /*
 384                  * range_cyclic:
 385                  * We hit the last page and there is more work to be done: wrap
 386                  * back to the start of the file
 387                  */
 388                 cycled = 1;
 389                 index = 0;
 390                 end = writeback_index - 1;
 391                 goto retry;
 392         }
 393
 394         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 395                 mapping->writeback_index = done_index;
 396
 397         return ret;
 398 }
 399
 400
 401 /**
 402  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 403  * @mapping: The mapping to write
 404  * @wbc: The writeback control
 405  *
 406  */
 407
 408 static int gfs2_jdata_writepages(struct address_space *mapping,
 409                                  struct writeback_control *wbc)
 410 {
 411         struct gfs2_inode *ip = GFS2_I(mapping->host);
 412         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 413         int ret;
 414
 415         ret = gfs2_write_cache_jdata(mapping, wbc);
 416         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 417                 gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
 418                                GFS2_LFC_JDATA_WPAGES);
 419                 ret = gfs2_write_cache_jdata(mapping, wbc);
 420         }
 421         return ret;
 422 }
 423
 424 /**
 425  * stuffed_readpage - Fill in a Linux page with stuffed file data
 426  * @ip: the inode
 427  * @page: the page
 428  *
 429  * Returns: errno
 430  */
 431 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 432 {
 433         struct buffer_head *dibh;
 434         u64 dsize = i_size_read(&ip->i_inode);
 435         void *kaddr;
 436         int error;
 437
 438         /*
 439          * Due to the order of unstuffing files and ->fault(), we can be
 440          * asked for a zero page in the case of a stuffed file being extended,
 441          * so we need to supply one here. It doesn't happen often.
 442          */
 443         if (unlikely(page->index)) {
 444                 zero_user(page, 0, PAGE_SIZE);
 445                 SetPageUptodate(page);
 446                 return 0;
 447         }
 448
 449         error = gfs2_meta_inode_buffer(ip, &dibh);
 450         if (error)
 451                 return error;
 452
 453         kaddr = kmap_atomic(page);
 454         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 455         memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
 456         kunmap_atomic(kaddr);
 457         flush_dcache_page(page);
 458         brelse(dibh);
 459         SetPageUptodate(page);
 460
 461         return 0;
 462 }
 463
 464
 465 static int __gfs2_readpage(void *file, struct page *page)
 466 {
 467         struct inode *inode = page->mapping->host;
 468         struct gfs2_inode *ip = GFS2_I(inode);
 469         struct gfs2_sbd *sdp = GFS2_SB(inode);
 470         int error;
 471
 472         if (!gfs2_is_jdata(ip) ||
 473             (i_blocksize(inode) == PAGE_SIZE && !page_has_buffers(page))) {
 474                 error = iomap_readpage(page, &gfs2_iomap_ops);
 475         } else if (gfs2_is_stuffed(ip)) {
 476                 error = stuffed_readpage(ip, page);
 477                 unlock_page(page);
 478         } else {
 479                 error = mpage_readpage(page, gfs2_block_map);
 480         }
 481
 482         if (unlikely(gfs2_withdrawn(sdp)))
 483                 return -EIO;
 484
 485         return error;
 486 }
 487
 488 /**
 489  * gfs2_readpage - read a page of a file
 490  * @file: The file to read
 491  * @page: The page of the file
 492  */
 493
 494 static int gfs2_readpage(struct file *file, struct page *page)
 495 {
 496         return __gfs2_readpage(file, page);
 497 }
 498
 499 /**
 500  * gfs2_internal_read - read an internal file
 501  * @ip: The gfs2 inode
 502  * @buf: The buffer to fill
 503  * @pos: The file position
 504  * @size: The amount to read
 505  *
 506  */
 507
 508 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
 509                        unsigned size)
 510 {
 511         struct address_space *mapping = ip->i_inode.i_mapping;
 512         unsigned long index = *pos >> PAGE_SHIFT;
 513         unsigned offset = *pos & (PAGE_SIZE - 1);
 514         unsigned copied = 0;
 515         unsigned amt;
 516         struct page *page;
 517         void *p;
 518
 519         do {
 520                 amt = size - copied;
 521                 if (offset + size > PAGE_SIZE)
 522                         amt = PAGE_SIZE - offset;
 523                 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
 524                 if (IS_ERR(page))
 525                         return PTR_ERR(page);
 526                 p = kmap_atomic(page);
 527                 memcpy(buf + copied, p + offset, amt);
 528                 kunmap_atomic(p);
 529                 put_page(page);
 530                 copied += amt;
 531                 index++;
 532                 offset = 0;
 533         } while(copied < size);
 534         (*pos) += size;
 535         return size;
 536 }
 537
 538 /**
 539  * gfs2_readahead - Read a bunch of pages at once
 540  * @file: The file to read from
 541  * @mapping: Address space info
 542  * @pages: List of pages to read
 543  * @nr_pages: Number of pages to read
 544  *
 545  * Some notes:
 546  * 1. This is only for readahead, so we can simply ignore any things
 547  *    which are slightly inconvenient (such as locking conflicts between
 548  *    the page lock and the glock) and return having done no I/O. Its
 549  *    obviously not something we'd want to do on too regular a basis.
 550  *    Any I/O we ignore at this time will be done via readpage later.
 551  * 2. We don't handle stuffed files here we let readpage do the honours.
 552  * 3. mpage_readahead() does most of the heavy lifting in the common case.
 553  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 554  */
 555
 556 static void gfs2_readahead(struct readahead_control *rac)
 557 {
 558         struct inode *inode = rac->mapping->host;
 559         struct gfs2_inode *ip = GFS2_I(inode);
 560
 561         if (gfs2_is_stuffed(ip))
 562                 ;
 563         else if (gfs2_is_jdata(ip))
 564                 mpage_readahead(rac, gfs2_block_map);
 565         else
 566                 iomap_readahead(rac, &gfs2_iomap_ops);
 567 }
 568
 569 /**
 570  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 571  * @inode: the rindex inode
 572  */
 573 void adjust_fs_space(struct inode *inode)
 574 {
 575         struct gfs2_sbd *sdp = GFS2_SB(inode);
 576         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 577         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 578         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 579         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 580         struct buffer_head *m_bh, *l_bh;
 581         u64 fs_total, new_free;
 582
 583         if (gfs2_trans_begin(sdp, 2 * RES_STATFS, 0) != 0)
 584                 return;
 585
 586         /* Total up the file system space, according to the latest rindex. */
 587         fs_total = gfs2_ri_total(sdp);
 588         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
 589                 goto out;
 590
 591         spin_lock(&sdp->sd_statfs_spin);
 592         gfs2_statfs_change_in(m_sc, m_bh->b_data +
 593                               sizeof(struct gfs2_dinode));
 594         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 595                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 596         else
 597                 new_free = 0;
 598         spin_unlock(&sdp->sd_statfs_spin);
 599         fs_warn(sdp, "File system extended by %llu blocks.\n",
 600                 (unsigned long long)new_free);
 601         gfs2_statfs_change(sdp, new_free, new_free, 0);
 602
 603         if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
 604                 goto out2;
 605         update_statfs(sdp, m_bh, l_bh);
 606         brelse(l_bh);
 607 out2:
 608         brelse(m_bh);
 609 out:
 610         sdp->sd_rindex_uptodate = 0;
 611         gfs2_trans_end(sdp);
 612 }
 613
 614 /**
 615  * jdata_set_page_dirty - Page dirtying function
 616  * @page: The page to dirty
 617  *
 618  * Returns: 1 if it dirtyed the page, or 0 otherwise
 619  */
 620
 621 static int jdata_set_page_dirty(struct page *page)
 622 {
 623         if (current->journal_info)
 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                         spin_lock(&sdp->sd_ail_lock);
 668                         gfs2_remove_from_journal(bh, REMOVE_JDATA);
 669                         spin_unlock(&sdp->sd_ail_lock);
 670                 }
 671         }
 672         bh->b_bdev = NULL;
 673         clear_buffer_mapped(bh);
 674         clear_buffer_req(bh);
 675         clear_buffer_new(bh);
 676         gfs2_log_unlock(sdp);
 677         unlock_buffer(bh);
 678 }
 679
 680 static void gfs2_invalidatepage(struct page *page, unsigned int offset,
 681                                 unsigned int length)
 682 {
 683         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 684         unsigned int stop = offset + length;
 685         int partial_page = (offset || length < PAGE_SIZE);
 686         struct buffer_head *bh, *head;
 687         unsigned long pos = 0;
 688
 689         BUG_ON(!PageLocked(page));
 690         if (!partial_page)
 691                 ClearPageChecked(page);
 692         if (!page_has_buffers(page))
 693                 goto out;
 694
 695         bh = head = page_buffers(page);
 696         do {
 697                 if (pos + bh->b_size > stop)
 698                         return;
 699
 700                 if (offset <= pos)
 701                         gfs2_discard(sdp, bh);
 702                 pos += bh->b_size;
 703                 bh = bh->b_this_page;
 704         } while (bh != head);
 705 out:
 706         if (!partial_page)
 707                 try_to_release_page(page, 0);
 708 }
 709
 710 /**
 711  * gfs2_releasepage - free the metadata associated with a page
 712  * @page: the page that's being released
 713  * @gfp_mask: passed from Linux VFS, ignored by us
 714  *
 715  * Calls try_to_free_buffers() to free the buffers and put the page if the
 716  * buffers can be released.
 717  *
 718  * Returns: 1 if the page was put or else 0
 719  */
 720
 721 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 722 {
 723         struct address_space *mapping = page->mapping;
 724         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 725         struct buffer_head *bh, *head;
 726         struct gfs2_bufdata *bd;
 727
 728         if (!page_has_buffers(page))
 729                 return 0;
 730
 731         /*
 732          * From xfs_vm_releasepage: mm accommodates an old ext3 case where
 733          * clean pages might not have had the dirty bit cleared.  Thus, it can
 734          * send actual dirty pages to ->releasepage() via shrink_active_list().
 735          *
 736          * As a workaround, we skip pages that contain dirty buffers below.
 737          * Once ->releasepage isn't called on dirty pages anymore, we can warn
 738          * on dirty buffers like we used to here again.
 739          */
 740
 741         gfs2_log_lock(sdp);
 742         head = bh = page_buffers(page);
 743         do {
 744                 if (atomic_read(&bh->b_count))
 745                         goto cannot_release;
 746                 bd = bh->b_private;
 747                 if (bd && bd->bd_tr)
 748                         goto cannot_release;
 749                 if (buffer_dirty(bh) || WARN_ON(buffer_pinned(bh)))
 750                         goto cannot_release;
 751                 bh = bh->b_this_page;
 752         } while(bh != head);
 753
 754         head = bh = page_buffers(page);
 755         do {
 756                 bd = bh->b_private;
 757                 if (bd) {
 758                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 759                         bd->bd_bh = NULL;
 760                         bh->b_private = NULL;
 761                         /*
 762                          * The bd may still be queued as a revoke, in which
 763                          * case we must not dequeue nor free it.
 764                          */
 765                         if (!bd->bd_blkno && !list_empty(&bd->bd_list))
 766                                 list_del_init(&bd->bd_list);
 767                         if (list_empty(&bd->bd_list))
 768                                 kmem_cache_free(gfs2_bufdata_cachep, bd);
 769                 }
 770
 771                 bh = bh->b_this_page;
 772         } while (bh != head);
 773         gfs2_log_unlock(sdp);
 774
 775         return try_to_free_buffers(page);
 776
 777 cannot_release:
 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         .set_page_dirty = iomap_set_page_dirty,
 788         .releasepage = iomap_releasepage,
 789         .invalidatepage = iomap_invalidatepage,
 790         .bmap = gfs2_bmap,
 791         .direct_IO = noop_direct_IO,
 792         .migratepage = iomap_migrate_page,
 793         .is_partially_uptodate = iomap_is_partially_uptodate,
 794         .error_remove_page = generic_error_remove_page,
 795 };
 796
 797 static const struct address_space_operations gfs2_jdata_aops = {
 798         .writepage = gfs2_jdata_writepage,
 799         .writepages = gfs2_jdata_writepages,
 800         .readpage = gfs2_readpage,
 801         .readahead = gfs2_readahead,
 802         .set_page_dirty = jdata_set_page_dirty,
 803         .bmap = gfs2_bmap,
 804         .invalidatepage = gfs2_invalidatepage,
 805         .releasepage = gfs2_releasepage,
 806         .is_partially_uptodate = block_is_partially_uptodate,
 807         .error_remove_page = generic_error_remove_page,
 808 };
 809
 810 void gfs2_set_aops(struct inode *inode)
 811 {
 812         if (gfs2_is_jdata(GFS2_I(inode)))
 813                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
 814         else
 815                 inode->i_mapping->a_ops = &gfs2_aops;
 816 }