fs/nilfs2/page.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Buffer/page management specific to NILFS
   4  *
   5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   6  *
   7  * Written by Ryusuke Konishi and Seiji Kihara.
   8  */
   9
  10 #include <linux/pagemap.h>
  11 #include <linux/writeback.h>
  12 #include <linux/swap.h>
  13 #include <linux/bitops.h>
  14 #include <linux/page-flags.h>
  15 #include <linux/list.h>
  16 #include <linux/highmem.h>
  17 #include <linux/pagevec.h>
  18 #include <linux/gfp.h>
  19 #include "nilfs.h"
  20 #include "page.h"
  21 #include "mdt.h"
  22
  23
  24 #define NILFS_BUFFER_INHERENT_BITS                                      \
  25         (BIT(BH_Uptodate) | BIT(BH_Mapped) | BIT(BH_NILFS_Node) |       \
  26          BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked))
  27
  28 static struct buffer_head *__nilfs_get_folio_block(struct folio *folio,
  29                 unsigned long block, pgoff_t index, int blkbits,
  30                 unsigned long b_state)
  31
  32 {
  33         unsigned long first_block;
  34         struct buffer_head *bh = folio_buffers(folio);
  35
  36         if (!bh)
  37                 bh = create_empty_buffers(folio, 1 << blkbits, b_state);
  38
  39         first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
  40         bh = get_nth_bh(bh, block - first_block);
  41
  42         touch_buffer(bh);
  43         wait_on_buffer(bh);
  44         return bh;
  45 }
  46
  47 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
  48                                       struct address_space *mapping,
  49                                       unsigned long blkoff,
  50                                       unsigned long b_state)
  51 {
  52         int blkbits = inode->i_blkbits;
  53         pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
  54         struct folio *folio;
  55         struct buffer_head *bh;
  56
  57         folio = filemap_grab_folio(mapping, index);
  58         if (IS_ERR(folio))
  59                 return NULL;
  60
  61         bh = __nilfs_get_folio_block(folio, blkoff, index, blkbits, b_state);
  62         if (unlikely(!bh)) {
  63                 folio_unlock(folio);
  64                 folio_put(folio);
  65                 return NULL;
  66         }
  67         return bh;
  68 }
  69
  70 /**
  71  * nilfs_forget_buffer - discard dirty state
  72  * @bh: buffer head of the buffer to be discarded
  73  */
  74 void nilfs_forget_buffer(struct buffer_head *bh)
  75 {
  76         struct folio *folio = bh->b_folio;
  77         const unsigned long clear_bits =
  78                 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
  79                  BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
  80                  BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
  81
  82         lock_buffer(bh);
  83         set_mask_bits(&bh->b_state, clear_bits, 0);
  84         if (nilfs_folio_buffers_clean(folio))
  85                 __nilfs_clear_folio_dirty(folio);
  86
  87         bh->b_blocknr = -1;
  88         folio_clear_uptodate(folio);
  89         folio_clear_mappedtodisk(folio);
  90         unlock_buffer(bh);
  91         brelse(bh);
  92 }
  93
  94 /**
  95  * nilfs_copy_buffer -- copy buffer data and flags
  96  * @dbh: destination buffer
  97  * @sbh: source buffer
  98  */
  99 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
 100 {
 101         void *kaddr0, *kaddr1;
 102         unsigned long bits;
 103         struct page *spage = sbh->b_page, *dpage = dbh->b_page;
 104         struct buffer_head *bh;
 105
 106         kaddr0 = kmap_atomic(spage);
 107         kaddr1 = kmap_atomic(dpage);
 108         memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
 109         kunmap_atomic(kaddr1);
 110         kunmap_atomic(kaddr0);
 111
 112         dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
 113         dbh->b_blocknr = sbh->b_blocknr;
 114         dbh->b_bdev = sbh->b_bdev;
 115
 116         bh = dbh;
 117         bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
 118         while ((bh = bh->b_this_page) != dbh) {
 119                 lock_buffer(bh);
 120                 bits &= bh->b_state;
 121                 unlock_buffer(bh);
 122         }
 123         if (bits & BIT(BH_Uptodate))
 124                 SetPageUptodate(dpage);
 125         else
 126                 ClearPageUptodate(dpage);
 127         if (bits & BIT(BH_Mapped))
 128                 SetPageMappedToDisk(dpage);
 129         else
 130                 ClearPageMappedToDisk(dpage);
 131 }
 132
 133 /**
 134  * nilfs_folio_buffers_clean - Check if a folio has dirty buffers or not.
 135  * @folio: Folio to be checked.
 136  *
 137  * nilfs_folio_buffers_clean() returns false if the folio has dirty buffers.
 138  * Otherwise, it returns true.
 139  */
 140 bool nilfs_folio_buffers_clean(struct folio *folio)
 141 {
 142         struct buffer_head *bh, *head;
 143
 144         bh = head = folio_buffers(folio);
 145         do {
 146                 if (buffer_dirty(bh))
 147                         return false;
 148                 bh = bh->b_this_page;
 149         } while (bh != head);
 150         return true;
 151 }
 152
 153 void nilfs_folio_bug(struct folio *folio)
 154 {
 155         struct buffer_head *bh, *head;
 156         struct address_space *m;
 157         unsigned long ino;
 158
 159         if (unlikely(!folio)) {
 160                 printk(KERN_CRIT "NILFS_FOLIO_BUG(NULL)\n");
 161                 return;
 162         }
 163
 164         m = folio->mapping;
 165         ino = m ? m->host->i_ino : 0;
 166
 167         printk(KERN_CRIT "NILFS_FOLIO_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 168                "mapping=%p ino=%lu\n",
 169                folio, folio_ref_count(folio),
 170                (unsigned long long)folio->index, folio->flags, m, ino);
 171
 172         head = folio_buffers(folio);
 173         if (head) {
 174                 int i = 0;
 175
 176                 bh = head;
 177                 do {
 178                         printk(KERN_CRIT
 179                                " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
 180                                i++, bh, atomic_read(&bh->b_count),
 181                                (unsigned long long)bh->b_blocknr, bh->b_state);
 182                         bh = bh->b_this_page;
 183                 } while (bh != head);
 184         }
 185 }
 186
 187 /**
 188  * nilfs_copy_folio -- copy the folio with buffers
 189  * @dst: destination folio
 190  * @src: source folio
 191  * @copy_dirty: flag whether to copy dirty states on the folio's buffer heads.
 192  *
 193  * This function is for both data folios and btnode folios.  The dirty flag
 194  * should be treated by caller.  The folio must not be under i/o.
 195  * Both src and dst folio must be locked
 196  */
 197 static void nilfs_copy_folio(struct folio *dst, struct folio *src,
 198                 bool copy_dirty)
 199 {
 200         struct buffer_head *dbh, *dbufs, *sbh;
 201         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
 202
 203         BUG_ON(folio_test_writeback(dst));
 204
 205         sbh = folio_buffers(src);
 206         dbh = folio_buffers(dst);
 207         if (!dbh)
 208                 dbh = create_empty_buffers(dst, sbh->b_size, 0);
 209
 210         if (copy_dirty)
 211                 mask |= BIT(BH_Dirty);
 212
 213         dbufs = dbh;
 214         do {
 215                 lock_buffer(sbh);
 216                 lock_buffer(dbh);
 217                 dbh->b_state = sbh->b_state & mask;
 218                 dbh->b_blocknr = sbh->b_blocknr;
 219                 dbh->b_bdev = sbh->b_bdev;
 220                 sbh = sbh->b_this_page;
 221                 dbh = dbh->b_this_page;
 222         } while (dbh != dbufs);
 223
 224         folio_copy(dst, src);
 225
 226         if (folio_test_uptodate(src) && !folio_test_uptodate(dst))
 227                 folio_mark_uptodate(dst);
 228         else if (!folio_test_uptodate(src) && folio_test_uptodate(dst))
 229                 folio_clear_uptodate(dst);
 230         if (folio_test_mappedtodisk(src) && !folio_test_mappedtodisk(dst))
 231                 folio_set_mappedtodisk(dst);
 232         else if (!folio_test_mappedtodisk(src) && folio_test_mappedtodisk(dst))
 233                 folio_clear_mappedtodisk(dst);
 234
 235         do {
 236                 unlock_buffer(sbh);
 237                 unlock_buffer(dbh);
 238                 sbh = sbh->b_this_page;
 239                 dbh = dbh->b_this_page;
 240         } while (dbh != dbufs);
 241 }
 242
 243 int nilfs_copy_dirty_pages(struct address_space *dmap,
 244                            struct address_space *smap)
 245 {
 246         struct folio_batch fbatch;
 247         unsigned int i;
 248         pgoff_t index = 0;
 249         int err = 0;
 250
 251         folio_batch_init(&fbatch);
 252 repeat:
 253         if (!filemap_get_folios_tag(smap, &index, (pgoff_t)-1,
 254                                 PAGECACHE_TAG_DIRTY, &fbatch))
 255                 return 0;
 256
 257         for (i = 0; i < folio_batch_count(&fbatch); i++) {
 258                 struct folio *folio = fbatch.folios[i], *dfolio;
 259
 260                 folio_lock(folio);
 261                 if (unlikely(!folio_test_dirty(folio)))
 262                         NILFS_FOLIO_BUG(folio, "inconsistent dirty state");
 263
 264                 dfolio = filemap_grab_folio(dmap, folio->index);
 265                 if (unlikely(IS_ERR(dfolio))) {
 266                         /* No empty page is added to the page cache */
 267                         folio_unlock(folio);
 268                         err = PTR_ERR(dfolio);
 269                         break;
 270                 }
 271                 if (unlikely(!folio_buffers(folio)))
 272                         NILFS_FOLIO_BUG(folio,
 273                                        "found empty page in dat page cache");
 274
 275                 nilfs_copy_folio(dfolio, folio, true);
 276                 filemap_dirty_folio(folio_mapping(dfolio), dfolio);
 277
 278                 folio_unlock(dfolio);
 279                 folio_put(dfolio);
 280                 folio_unlock(folio);
 281         }
 282         folio_batch_release(&fbatch);
 283         cond_resched();
 284
 285         if (likely(!err))
 286                 goto repeat;
 287         return err;
 288 }
 289
 290 /**
 291  * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
 292  * @dmap: destination page cache
 293  * @smap: source page cache
 294  *
 295  * No pages must be added to the cache during this process.
 296  * This must be ensured by the caller.
 297  */
 298 void nilfs_copy_back_pages(struct address_space *dmap,
 299                            struct address_space *smap)
 300 {
 301         struct folio_batch fbatch;
 302         unsigned int i, n;
 303         pgoff_t start = 0;
 304
 305         folio_batch_init(&fbatch);
 306 repeat:
 307         n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
 308         if (!n)
 309                 return;
 310
 311         for (i = 0; i < folio_batch_count(&fbatch); i++) {
 312                 struct folio *folio = fbatch.folios[i], *dfolio;
 313                 pgoff_t index = folio->index;
 314
 315                 folio_lock(folio);
 316                 dfolio = filemap_lock_folio(dmap, index);
 317                 if (!IS_ERR(dfolio)) {
 318                         /* overwrite existing folio in the destination cache */
 319                         WARN_ON(folio_test_dirty(dfolio));
 320                         nilfs_copy_folio(dfolio, folio, false);
 321                         folio_unlock(dfolio);
 322                         folio_put(dfolio);
 323                         /* Do we not need to remove folio from smap here? */
 324                 } else {
 325                         struct folio *f;
 326
 327                         /* move the folio to the destination cache */
 328                         xa_lock_irq(&smap->i_pages);
 329                         f = __xa_erase(&smap->i_pages, index);
 330                         WARN_ON(folio != f);
 331                         smap->nrpages--;
 332                         xa_unlock_irq(&smap->i_pages);
 333
 334                         xa_lock_irq(&dmap->i_pages);
 335                         f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
 336                         if (unlikely(f)) {
 337                                 /* Probably -ENOMEM */
 338                                 folio->mapping = NULL;
 339                                 folio_put(folio);
 340                         } else {
 341                                 folio->mapping = dmap;
 342                                 dmap->nrpages++;
 343                                 if (folio_test_dirty(folio))
 344                                         __xa_set_mark(&dmap->i_pages, index,
 345                                                         PAGECACHE_TAG_DIRTY);
 346                         }
 347                         xa_unlock_irq(&dmap->i_pages);
 348                 }
 349                 folio_unlock(folio);
 350         }
 351         folio_batch_release(&fbatch);
 352         cond_resched();
 353
 354         goto repeat;
 355 }
 356
 357 /**
 358  * nilfs_clear_dirty_pages - discard dirty pages in address space
 359  * @mapping: address space with dirty pages for discarding
 360  * @silent: suppress [true] or print [false] warning messages
 361  */
 362 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
 363 {
 364         struct folio_batch fbatch;
 365         unsigned int i;
 366         pgoff_t index = 0;
 367
 368         folio_batch_init(&fbatch);
 369
 370         while (filemap_get_folios_tag(mapping, &index, (pgoff_t)-1,
 371                                 PAGECACHE_TAG_DIRTY, &fbatch)) {
 372                 for (i = 0; i < folio_batch_count(&fbatch); i++) {
 373                         struct folio *folio = fbatch.folios[i];
 374
 375                         folio_lock(folio);
 376
 377                         /*
 378                          * This folio may have been removed from the address
 379                          * space by truncation or invalidation when the lock
 380                          * was acquired.  Skip processing in that case.
 381                          */
 382                         if (likely(folio->mapping == mapping))
 383                                 nilfs_clear_folio_dirty(folio, silent);
 384
 385                         folio_unlock(folio);
 386                 }
 387                 folio_batch_release(&fbatch);
 388                 cond_resched();
 389         }
 390 }
 391
 392 /**
 393  * nilfs_clear_folio_dirty - discard dirty folio
 394  * @folio: dirty folio that will be discarded
 395  * @silent: suppress [true] or print [false] warning messages
 396  */
 397 void nilfs_clear_folio_dirty(struct folio *folio, bool silent)
 398 {
 399         struct inode *inode = folio->mapping->host;
 400         struct super_block *sb = inode->i_sb;
 401         struct buffer_head *bh, *head;
 402
 403         BUG_ON(!folio_test_locked(folio));
 404
 405         if (!silent)
 406                 nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
 407                            folio_pos(folio), inode->i_ino);
 408
 409         folio_clear_uptodate(folio);
 410         folio_clear_mappedtodisk(folio);
 411
 412         head = folio_buffers(folio);
 413         if (head) {
 414                 const unsigned long clear_bits =
 415                         (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
 416                          BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
 417                          BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
 418
 419                 bh = head;
 420                 do {
 421                         lock_buffer(bh);
 422                         if (!silent)
 423                                 nilfs_warn(sb,
 424                                            "discard dirty block: blocknr=%llu, size=%zu",
 425                                            (u64)bh->b_blocknr, bh->b_size);
 426
 427                         set_mask_bits(&bh->b_state, clear_bits, 0);
 428                         unlock_buffer(bh);
 429                 } while (bh = bh->b_this_page, bh != head);
 430         }
 431
 432         __nilfs_clear_folio_dirty(folio);
 433 }
 434
 435 unsigned int nilfs_page_count_clean_buffers(struct page *page,
 436                                             unsigned int from, unsigned int to)
 437 {
 438         unsigned int block_start, block_end;
 439         struct buffer_head *bh, *head;
 440         unsigned int nc = 0;
 441
 442         for (bh = head = page_buffers(page), block_start = 0;
 443              bh != head || !block_start;
 444              block_start = block_end, bh = bh->b_this_page) {
 445                 block_end = block_start + bh->b_size;
 446                 if (block_end > from && block_start < to && !buffer_dirty(bh))
 447                         nc++;
 448         }
 449         return nc;
 450 }
 451
 452 /*
 453  * NILFS2 needs clear_page_dirty() in the following two cases:
 454  *
 455  * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
 456  *    flag of pages when it copies back pages from shadow cache to the
 457  *    original cache.
 458  *
 459  * 2) Some B-tree operations like insertion or deletion may dispose buffers
 460  *    in dirty state, and this needs to cancel the dirty state of their pages.
 461  */
 462 void __nilfs_clear_folio_dirty(struct folio *folio)
 463 {
 464         struct address_space *mapping = folio->mapping;
 465
 466         if (mapping) {
 467                 xa_lock_irq(&mapping->i_pages);
 468                 if (folio_test_dirty(folio)) {
 469                         __xa_clear_mark(&mapping->i_pages, folio->index,
 470                                              PAGECACHE_TAG_DIRTY);
 471                         xa_unlock_irq(&mapping->i_pages);
 472                         folio_clear_dirty_for_io(folio);
 473                         return;
 474                 }
 475                 xa_unlock_irq(&mapping->i_pages);
 476                 return;
 477         }
 478         folio_clear_dirty(folio);
 479 }
 480
 481 /**
 482  * nilfs_find_uncommitted_extent - find extent of uncommitted data
 483  * @inode: inode
 484  * @start_blk: start block offset (in)
 485  * @blkoff: start offset of the found extent (out)
 486  *
 487  * This function searches an extent of buffers marked "delayed" which
 488  * starts from a block offset equal to or larger than @start_blk.  If
 489  * such an extent was found, this will store the start offset in
 490  * @blkoff and return its length in blocks.  Otherwise, zero is
 491  * returned.
 492  */
 493 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 494                                             sector_t start_blk,
 495                                             sector_t *blkoff)
 496 {
 497         unsigned int i, nr_folios;
 498         pgoff_t index;
 499         unsigned long length = 0;
 500         struct folio_batch fbatch;
 501         struct folio *folio;
 502
 503         if (inode->i_mapping->nrpages == 0)
 504                 return 0;
 505
 506         index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
 507
 508         folio_batch_init(&fbatch);
 509
 510 repeat:
 511         nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
 512                         &fbatch);
 513         if (nr_folios == 0)
 514                 return length;
 515
 516         i = 0;
 517         do {
 518                 folio = fbatch.folios[i];
 519
 520                 folio_lock(folio);
 521                 if (folio_buffers(folio)) {
 522                         struct buffer_head *bh, *head;
 523                         sector_t b;
 524
 525                         b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
 526                         bh = head = folio_buffers(folio);
 527                         do {
 528                                 if (b < start_blk)
 529                                         continue;
 530                                 if (buffer_delay(bh)) {
 531                                         if (length == 0)
 532                                                 *blkoff = b;
 533                                         length++;
 534                                 } else if (length > 0) {
 535                                         goto out_locked;
 536                                 }
 537                         } while (++b, bh = bh->b_this_page, bh != head);
 538                 } else {
 539                         if (length > 0)
 540                                 goto out_locked;
 541                 }
 542                 folio_unlock(folio);
 543
 544         } while (++i < nr_folios);
 545
 546         folio_batch_release(&fbatch);
 547         cond_resched();
 548         goto repeat;
 549
 550 out_locked:
 551         folio_unlock(folio);
 552         folio_batch_release(&fbatch);
 553         return length;
 554 }