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         struct gfs2_sbd *sdp = GFS2_SB(inode);
 156
 157         if (PageChecked(page)) {
 158                 ClearPageChecked(page);
 159                 if (!page_has_buffers(page)) {
 160                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 161                                              BIT(BH_Dirty)|BIT(BH_Uptodate));
 162                 }
 163                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize);
 164         }
 165         return gfs2_write_jdata_page(page, wbc);
 166 }
 167
 168 /**
 169  * gfs2_jdata_writepage - Write complete page
 170  * @page: Page to write
 171  * @wbc: The writeback control
 172  *
 173  * Returns: errno
 174  *
 175  */
 176
 177 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 178 {
 179         struct inode *inode = page->mapping->host;
 180         struct gfs2_inode *ip = GFS2_I(inode);
 181         struct gfs2_sbd *sdp = GFS2_SB(inode);
 182
 183         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 184                 goto out;
 185         if (PageChecked(page) || current->journal_info)
 186                 goto out_ignore;
 187         return __gfs2_jdata_writepage(page, wbc);
 188
 189 out_ignore:
 190         redirty_page_for_writepage(wbc, page);
 191 out:
 192         unlock_page(page);
 193         return 0;
 194 }
 195
 196 /**
 197  * gfs2_writepages - Write a bunch of dirty pages back to disk
 198  * @mapping: The mapping to write
 199  * @wbc: Write-back control
 200  *
 201  * Used for both ordered and writeback modes.
 202  */
 203 static int gfs2_writepages(struct address_space *mapping,
 204                            struct writeback_control *wbc)
 205 {
 206         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 207         struct iomap_writepage_ctx wpc = { };
 208         int ret;
 209
 210         /*
 211          * Even if we didn't write any pages here, we might still be holding
 212          * dirty pages in the ail. We forcibly flush the ail because we don't
 213          * want balance_dirty_pages() to loop indefinitely trying to write out
 214          * pages held in the ail that it can't find.
 215          */
 216         ret = iomap_writepages(mapping, wbc, &wpc, &gfs2_writeback_ops);
 217         if (ret == 0)
 218                 set_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
 219         return ret;
 220 }
 221
 222 /**
 223  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 224  * @mapping: The mapping
 225  * @wbc: The writeback control
 226  * @pvec: The vector of pages
 227  * @nr_pages: The number of pages to write
 228  * @done_index: Page index
 229  *
 230  * Returns: non-zero if loop should terminate, zero otherwise
 231  */
 232
 233 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 234                                     struct writeback_control *wbc,
 235                                     struct pagevec *pvec,
 236                                     int nr_pages,
 237                                     pgoff_t *done_index)
 238 {
 239         struct inode *inode = mapping->host;
 240         struct gfs2_sbd *sdp = GFS2_SB(inode);
 241         unsigned nrblocks = nr_pages * (PAGE_SIZE >> inode->i_blkbits);
 242         int i;
 243         int ret;
 244
 245         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 246         if (ret < 0)
 247                 return ret;
 248
 249         for(i = 0; i < nr_pages; i++) {
 250                 struct page *page = pvec->pages[i];
 251
 252                 *done_index = page->index;
 253
 254                 lock_page(page);
 255
 256                 if (unlikely(page->mapping != mapping)) {
 257 continue_unlock:
 258                         unlock_page(page);
 259                         continue;
 260                 }
 261
 262                 if (!PageDirty(page)) {
 263                         /* someone wrote it for us */
 264                         goto continue_unlock;
 265                 }
 266
 267                 if (PageWriteback(page)) {
 268                         if (wbc->sync_mode != WB_SYNC_NONE)
 269                                 wait_on_page_writeback(page);
 270                         else
 271                                 goto continue_unlock;
 272                 }
 273
 274                 BUG_ON(PageWriteback(page));
 275                 if (!clear_page_dirty_for_io(page))
 276                         goto continue_unlock;
 277
 278                 trace_wbc_writepage(wbc, inode_to_bdi(inode));
 279
 280                 ret = __gfs2_jdata_writepage(page, wbc);
 281                 if (unlikely(ret)) {
 282                         if (ret == AOP_WRITEPAGE_ACTIVATE) {
 283                                 unlock_page(page);
 284                                 ret = 0;
 285                         } else {
 286
 287                                 /*
 288                                  * done_index is set past this page,
 289                                  * so media errors will not choke
 290                                  * background writeout for the entire
 291                                  * file. This has consequences for
 292                                  * range_cyclic semantics (ie. it may
 293                                  * not be suitable for data integrity
 294                                  * writeout).
 295                                  */
 296                                 *done_index = page->index + 1;
 297                                 ret = 1;
 298                                 break;
 299                         }
 300                 }
 301
 302                 /*
 303                  * We stop writing back only if we are not doing
 304                  * integrity sync. In case of integrity sync we have to
 305                  * keep going until we have written all the pages
 306                  * we tagged for writeback prior to entering this loop.
 307                  */
 308                 if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
 309                         ret = 1;
 310                         break;
 311                 }
 312
 313         }
 314         gfs2_trans_end(sdp);
 315         return ret;
 316 }
 317
 318 /**
 319  * gfs2_write_cache_jdata - Like write_cache_pages but different
 320  * @mapping: The mapping to write
 321  * @wbc: The writeback control
 322  *
 323  * The reason that we use our own function here is that we need to
 324  * start transactions before we grab page locks. This allows us
 325  * to get the ordering right.
 326  */
 327
 328 static int gfs2_write_cache_jdata(struct address_space *mapping,
 329                                   struct writeback_control *wbc)
 330 {
 331         int ret = 0;
 332         int done = 0;
 333         struct pagevec pvec;
 334         int nr_pages;
 335         pgoff_t writeback_index;
 336         pgoff_t index;
 337         pgoff_t end;
 338         pgoff_t done_index;
 339         int cycled;
 340         int range_whole = 0;
 341         xa_mark_t tag;
 342
 343         pagevec_init(&pvec);
 344         if (wbc->range_cyclic) {
 345                 writeback_index = mapping->writeback_index; /* prev offset */
 346                 index = writeback_index;
 347                 if (index == 0)
 348                         cycled = 1;
 349                 else
 350                         cycled = 0;
 351                 end = -1;
 352         } else {
 353                 index = wbc->range_start >> PAGE_SHIFT;
 354                 end = wbc->range_end >> PAGE_SHIFT;
 355                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 356                         range_whole = 1;
 357                 cycled = 1; /* ignore range_cyclic tests */
 358         }
 359         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 360                 tag = PAGECACHE_TAG_TOWRITE;
 361         else
 362                 tag = PAGECACHE_TAG_DIRTY;
 363
 364 retry:
 365         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 366                 tag_pages_for_writeback(mapping, index, end);
 367         done_index = index;
 368         while (!done && (index <= end)) {
 369                 nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
 370                                 tag);
 371                 if (nr_pages == 0)
 372                         break;
 373
 374                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, &done_index);
 375                 if (ret)
 376                         done = 1;
 377                 if (ret > 0)
 378                         ret = 0;
 379                 pagevec_release(&pvec);
 380                 cond_resched();
 381         }
 382
 383         if (!cycled && !done) {
 384                 /*
 385                  * range_cyclic:
 386                  * We hit the last page and there is more work to be done: wrap
 387                  * back to the start of the file
 388                  */
 389                 cycled = 1;
 390                 index = 0;
 391                 end = writeback_index - 1;
 392                 goto retry;
 393         }
 394
 395         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 396                 mapping->writeback_index = done_index;
 397
 398         return ret;
 399 }
 400
 401
 402 /**
 403  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 404  * @mapping: The mapping to write
 405  * @wbc: The writeback control
 406  *
 407  */
 408
 409 static int gfs2_jdata_writepages(struct address_space *mapping,
 410                                  struct writeback_control *wbc)
 411 {
 412         struct gfs2_inode *ip = GFS2_I(mapping->host);
 413         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 414         int ret;
 415
 416         ret = gfs2_write_cache_jdata(mapping, wbc);
 417         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 418                 gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
 419                                GFS2_LFC_JDATA_WPAGES);
 420                 ret = gfs2_write_cache_jdata(mapping, wbc);
 421         }
 422         return ret;
 423 }
 424
 425 /**
 426  * stuffed_readpage - Fill in a Linux page with stuffed file data
 427  * @ip: the inode
 428  * @page: the page
 429  *
 430  * Returns: errno
 431  */
 432 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 433 {
 434         struct buffer_head *dibh;
 435         u64 dsize = i_size_read(&ip->i_inode);
 436         void *kaddr;
 437         int error;
 438
 439         /*
 440          * Due to the order of unstuffing files and ->fault(), we can be
 441          * asked for a zero page in the case of a stuffed file being extended,
 442          * so we need to supply one here. It doesn't happen often.
 443          */
 444         if (unlikely(page->index)) {
 445                 zero_user(page, 0, PAGE_SIZE);
 446                 SetPageUptodate(page);
 447                 return 0;
 448         }
 449
 450         error = gfs2_meta_inode_buffer(ip, &dibh);
 451         if (error)
 452                 return error;
 453
 454         kaddr = kmap_atomic(page);
 455         if (dsize > gfs2_max_stuffed_size(ip))
 456                 dsize = gfs2_max_stuffed_size(ip);
 457         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 458         memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
 459         kunmap_atomic(kaddr);
 460         flush_dcache_page(page);
 461         brelse(dibh);
 462         SetPageUptodate(page);
 463
 464         return 0;
 465 }
 466
 467 /**
 468  * gfs2_read_folio - read a folio from a file
 469  * @file: The file to read
 470  * @folio: The folio in the file
 471  */
 472 static int gfs2_read_folio(struct file *file, struct folio *folio)
 473 {
 474         struct inode *inode = folio->mapping->host;
 475         struct gfs2_inode *ip = GFS2_I(inode);
 476         struct gfs2_sbd *sdp = GFS2_SB(inode);
 477         int error;
 478
 479         if (!gfs2_is_jdata(ip) ||
 480             (i_blocksize(inode) == PAGE_SIZE && !folio_buffers(folio))) {
 481                 error = iomap_read_folio(folio, &gfs2_iomap_ops);
 482         } else if (gfs2_is_stuffed(ip)) {
 483                 error = stuffed_readpage(ip, &folio->page);
 484                 folio_unlock(folio);
 485         } else {
 486                 error = mpage_read_folio(folio, gfs2_block_map);
 487         }
 488
 489         if (unlikely(gfs2_withdrawn(sdp)))
 490                 return -EIO;
 491
 492         return error;
 493 }
 494
 495 /**
 496  * gfs2_internal_read - read an internal file
 497  * @ip: The gfs2 inode
 498  * @buf: The buffer to fill
 499  * @pos: The file position
 500  * @size: The amount to read
 501  *
 502  */
 503
 504 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
 505                        unsigned size)
 506 {
 507         struct address_space *mapping = ip->i_inode.i_mapping;
 508         unsigned long index = *pos >> PAGE_SHIFT;
 509         unsigned offset = *pos & (PAGE_SIZE - 1);
 510         unsigned copied = 0;
 511         unsigned amt;
 512         struct page *page;
 513         void *p;
 514
 515         do {
 516                 amt = size - copied;
 517                 if (offset + size > PAGE_SIZE)
 518                         amt = PAGE_SIZE - offset;
 519                 page = read_cache_page(mapping, index, gfs2_read_folio, NULL);
 520                 if (IS_ERR(page))
 521                         return PTR_ERR(page);
 522                 p = kmap_atomic(page);
 523                 memcpy(buf + copied, p + offset, amt);
 524                 kunmap_atomic(p);
 525                 put_page(page);
 526                 copied += amt;
 527                 index++;
 528                 offset = 0;
 529         } while(copied < size);
 530         (*pos) += size;
 531         return size;
 532 }
 533
 534 /**
 535  * gfs2_readahead - Read a bunch of pages at once
 536  * @rac: Read-ahead control structure
 537  *
 538  * Some notes:
 539  * 1. This is only for readahead, so we can simply ignore any things
 540  *    which are slightly inconvenient (such as locking conflicts between
 541  *    the page lock and the glock) and return having done no I/O. Its
 542  *    obviously not something we'd want to do on too regular a basis.
 543  *    Any I/O we ignore at this time will be done via readpage later.
 544  * 2. We don't handle stuffed files here we let readpage do the honours.
 545  * 3. mpage_readahead() does most of the heavy lifting in the common case.
 546  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 547  */
 548
 549 static void gfs2_readahead(struct readahead_control *rac)
 550 {
 551         struct inode *inode = rac->mapping->host;
 552         struct gfs2_inode *ip = GFS2_I(inode);
 553
 554         if (gfs2_is_stuffed(ip))
 555                 ;
 556         else if (gfs2_is_jdata(ip))
 557                 mpage_readahead(rac, gfs2_block_map);
 558         else
 559                 iomap_readahead(rac, &gfs2_iomap_ops);
 560 }
 561
 562 /**
 563  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 564  * @inode: the rindex inode
 565  */
 566 void adjust_fs_space(struct inode *inode)
 567 {
 568         struct gfs2_sbd *sdp = GFS2_SB(inode);
 569         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 570         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 571         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 572         struct buffer_head *m_bh;
 573         u64 fs_total, new_free;
 574
 575         if (gfs2_trans_begin(sdp, 2 * RES_STATFS, 0) != 0)
 576                 return;
 577
 578         /* Total up the file system space, according to the latest rindex. */
 579         fs_total = gfs2_ri_total(sdp);
 580         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
 581                 goto out;
 582
 583         spin_lock(&sdp->sd_statfs_spin);
 584         gfs2_statfs_change_in(m_sc, m_bh->b_data +
 585                               sizeof(struct gfs2_dinode));
 586         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 587                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 588         else
 589                 new_free = 0;
 590         spin_unlock(&sdp->sd_statfs_spin);
 591         fs_warn(sdp, "File system extended by %llu blocks.\n",
 592                 (unsigned long long)new_free);
 593         gfs2_statfs_change(sdp, new_free, new_free, 0);
 594
 595         update_statfs(sdp, m_bh);
 596         brelse(m_bh);
 597 out:
 598         sdp->sd_rindex_uptodate = 0;
 599         gfs2_trans_end(sdp);
 600 }
 601
 602 static bool jdata_dirty_folio(struct address_space *mapping,
 603                 struct folio *folio)
 604 {
 605         if (current->journal_info)
 606                 folio_set_checked(folio);
 607         return block_dirty_folio(mapping, folio);
 608 }
 609
 610 /**
 611  * gfs2_bmap - Block map function
 612  * @mapping: Address space info
 613  * @lblock: The block to map
 614  *
 615  * Returns: The disk address for the block or 0 on hole or error
 616  */
 617
 618 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 619 {
 620         struct gfs2_inode *ip = GFS2_I(mapping->host);
 621         struct gfs2_holder i_gh;
 622         sector_t dblock = 0;
 623         int error;
 624
 625         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 626         if (error)
 627                 return 0;
 628
 629         if (!gfs2_is_stuffed(ip))
 630                 dblock = iomap_bmap(mapping, lblock, &gfs2_iomap_ops);
 631
 632         gfs2_glock_dq_uninit(&i_gh);
 633
 634         return dblock;
 635 }
 636
 637 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 638 {
 639         struct gfs2_bufdata *bd;
 640
 641         lock_buffer(bh);
 642         gfs2_log_lock(sdp);
 643         clear_buffer_dirty(bh);
 644         bd = bh->b_private;
 645         if (bd) {
 646                 if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
 647                         list_del_init(&bd->bd_list);
 648                 else {
 649                         spin_lock(&sdp->sd_ail_lock);
 650                         gfs2_remove_from_journal(bh, REMOVE_JDATA);
 651                         spin_unlock(&sdp->sd_ail_lock);
 652                 }
 653         }
 654         bh->b_bdev = NULL;
 655         clear_buffer_mapped(bh);
 656         clear_buffer_req(bh);
 657         clear_buffer_new(bh);
 658         gfs2_log_unlock(sdp);
 659         unlock_buffer(bh);
 660 }
 661
 662 static void gfs2_invalidate_folio(struct folio *folio, size_t offset,
 663                                 size_t length)
 664 {
 665         struct gfs2_sbd *sdp = GFS2_SB(folio->mapping->host);
 666         size_t stop = offset + length;
 667         int partial_page = (offset || length < folio_size(folio));
 668         struct buffer_head *bh, *head;
 669         unsigned long pos = 0;
 670
 671         BUG_ON(!folio_test_locked(folio));
 672         if (!partial_page)
 673                 folio_clear_checked(folio);
 674         head = folio_buffers(folio);
 675         if (!head)
 676                 goto out;
 677
 678         bh = head;
 679         do {
 680                 if (pos + bh->b_size > stop)
 681                         return;
 682
 683                 if (offset <= pos)
 684                         gfs2_discard(sdp, bh);
 685                 pos += bh->b_size;
 686                 bh = bh->b_this_page;
 687         } while (bh != head);
 688 out:
 689         if (!partial_page)
 690                 filemap_release_folio(folio, 0);
 691 }
 692
 693 /**
 694  * gfs2_release_folio - free the metadata associated with a folio
 695  * @folio: the folio that's being released
 696  * @gfp_mask: passed from Linux VFS, ignored by us
 697  *
 698  * Calls try_to_free_buffers() to free the buffers and put the folio if the
 699  * buffers can be released.
 700  *
 701  * Returns: true if the folio was put or else false
 702  */
 703
 704 bool gfs2_release_folio(struct folio *folio, gfp_t gfp_mask)
 705 {
 706         struct address_space *mapping = folio->mapping;
 707         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 708         struct buffer_head *bh, *head;
 709         struct gfs2_bufdata *bd;
 710
 711         head = folio_buffers(folio);
 712         if (!head)
 713                 return false;
 714
 715         /*
 716          * mm accommodates an old ext3 case where clean folios might
 717          * not have had the dirty bit cleared.  Thus, it can send actual
 718          * dirty folios to ->release_folio() via shrink_active_list().
 719          *
 720          * As a workaround, we skip folios that contain dirty buffers
 721          * below.  Once ->release_folio isn't called on dirty folios
 722          * anymore, we can warn on dirty buffers like we used to here
 723          * again.
 724          */
 725
 726         gfs2_log_lock(sdp);
 727         bh = head;
 728         do {
 729                 if (atomic_read(&bh->b_count))
 730                         goto cannot_release;
 731                 bd = bh->b_private;
 732                 if (bd && bd->bd_tr)
 733                         goto cannot_release;
 734                 if (buffer_dirty(bh) || WARN_ON(buffer_pinned(bh)))
 735                         goto cannot_release;
 736                 bh = bh->b_this_page;
 737         } while (bh != head);
 738
 739         bh = head;
 740         do {
 741                 bd = bh->b_private;
 742                 if (bd) {
 743                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 744                         bd->bd_bh = NULL;
 745                         bh->b_private = NULL;
 746                         /*
 747                          * The bd may still be queued as a revoke, in which
 748                          * case we must not dequeue nor free it.
 749                          */
 750                         if (!bd->bd_blkno && !list_empty(&bd->bd_list))
 751                                 list_del_init(&bd->bd_list);
 752                         if (list_empty(&bd->bd_list))
 753                                 kmem_cache_free(gfs2_bufdata_cachep, bd);
 754                 }
 755
 756                 bh = bh->b_this_page;
 757         } while (bh != head);
 758         gfs2_log_unlock(sdp);
 759
 760         return try_to_free_buffers(folio);
 761
 762 cannot_release:
 763         gfs2_log_unlock(sdp);
 764         return false;
 765 }
 766
 767 static const struct address_space_operations gfs2_aops = {
 768         .writepage = gfs2_writepage,
 769         .writepages = gfs2_writepages,
 770         .read_folio = gfs2_read_folio,
 771         .readahead = gfs2_readahead,
 772         .dirty_folio = filemap_dirty_folio,
 773         .release_folio = iomap_release_folio,
 774         .invalidate_folio = iomap_invalidate_folio,
 775         .bmap = gfs2_bmap,
 776         .direct_IO = noop_direct_IO,
 777         .migrate_folio = filemap_migrate_folio,
 778         .is_partially_uptodate = iomap_is_partially_uptodate,
 779         .error_remove_page = generic_error_remove_page,
 780 };
 781
 782 static const struct address_space_operations gfs2_jdata_aops = {
 783         .writepage = gfs2_jdata_writepage,
 784         .writepages = gfs2_jdata_writepages,
 785         .read_folio = gfs2_read_folio,
 786         .readahead = gfs2_readahead,
 787         .dirty_folio = jdata_dirty_folio,
 788         .bmap = gfs2_bmap,
 789         .invalidate_folio = gfs2_invalidate_folio,
 790         .release_folio = gfs2_release_folio,
 791         .is_partially_uptodate = block_is_partially_uptodate,
 792         .error_remove_page = generic_error_remove_page,
 793 };
 794
 795 void gfs2_set_aops(struct inode *inode)
 796 {
 797         if (gfs2_is_jdata(GFS2_I(inode)))
 798                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
 799         else
 800                 inode->i_mapping->a_ops = &gfs2_aops;
 801 }