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 *
  29 __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
  30                        int blkbits, unsigned long b_state)
  31
  32 {
  33         unsigned long first_block;
  34         struct buffer_head *bh;
  35
  36         if (!page_has_buffers(page))
  37                 create_empty_buffers(page, 1 << blkbits, b_state);
  38
  39         first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
  40         bh = nilfs_page_get_nth_block(page, 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 page *page;
  55         struct buffer_head *bh;
  56
  57         page = grab_cache_page(mapping, index);
  58         if (unlikely(!page))
  59                 return NULL;
  60
  61         bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
  62         if (unlikely(!bh)) {
  63                 unlock_page(page);
  64                 put_page(page);
  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 page *page = bh->b_page;
  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_page_buffers_clean(page))
  85                 __nilfs_clear_page_dirty(page);
  86
  87         bh->b_blocknr = -1;
  88         ClearPageUptodate(page);
  89         ClearPageMappedToDisk(page);
  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_page_buffers_clean - check if a page has dirty buffers or not.
 135  * @page: page to be checked
 136  *
 137  * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 138  * Otherwise, it returns non-zero value.
 139  */
 140 int nilfs_page_buffers_clean(struct page *page)
 141 {
 142         struct buffer_head *bh, *head;
 143
 144         bh = head = page_buffers(page);
 145         do {
 146                 if (buffer_dirty(bh))
 147                         return 0;
 148                 bh = bh->b_this_page;
 149         } while (bh != head);
 150         return 1;
 151 }
 152
 153 void nilfs_page_bug(struct page *page)
 154 {
 155         struct address_space *m;
 156         unsigned long ino;
 157
 158         if (unlikely(!page)) {
 159                 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
 160                 return;
 161         }
 162
 163         m = page->mapping;
 164         ino = m ? m->host->i_ino : 0;
 165
 166         printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 167                "mapping=%p ino=%lu\n",
 168                page, page_ref_count(page),
 169                (unsigned long long)page->index, page->flags, m, ino);
 170
 171         if (page_has_buffers(page)) {
 172                 struct buffer_head *bh, *head;
 173                 int i = 0;
 174
 175                 bh = head = page_buffers(page);
 176                 do {
 177                         printk(KERN_CRIT
 178                                " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
 179                                i++, bh, atomic_read(&bh->b_count),
 180                                (unsigned long long)bh->b_blocknr, bh->b_state);
 181                         bh = bh->b_this_page;
 182                 } while (bh != head);
 183         }
 184 }
 185
 186 /**
 187  * nilfs_copy_page -- copy the page with buffers
 188  * @dst: destination page
 189  * @src: source page
 190  * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
 191  *
 192  * This function is for both data pages and btnode pages.  The dirty flag
 193  * should be treated by caller.  The page must not be under i/o.
 194  * Both src and dst page must be locked
 195  */
 196 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
 197 {
 198         struct buffer_head *dbh, *dbufs, *sbh;
 199         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
 200
 201         BUG_ON(PageWriteback(dst));
 202
 203         sbh = page_buffers(src);
 204         if (!page_has_buffers(dst))
 205                 create_empty_buffers(dst, sbh->b_size, 0);
 206
 207         if (copy_dirty)
 208                 mask |= BIT(BH_Dirty);
 209
 210         dbh = dbufs = page_buffers(dst);
 211         do {
 212                 lock_buffer(sbh);
 213                 lock_buffer(dbh);
 214                 dbh->b_state = sbh->b_state & mask;
 215                 dbh->b_blocknr = sbh->b_blocknr;
 216                 dbh->b_bdev = sbh->b_bdev;
 217                 sbh = sbh->b_this_page;
 218                 dbh = dbh->b_this_page;
 219         } while (dbh != dbufs);
 220
 221         copy_highpage(dst, src);
 222
 223         if (PageUptodate(src) && !PageUptodate(dst))
 224                 SetPageUptodate(dst);
 225         else if (!PageUptodate(src) && PageUptodate(dst))
 226                 ClearPageUptodate(dst);
 227         if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
 228                 SetPageMappedToDisk(dst);
 229         else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
 230                 ClearPageMappedToDisk(dst);
 231
 232         do {
 233                 unlock_buffer(sbh);
 234                 unlock_buffer(dbh);
 235                 sbh = sbh->b_this_page;
 236                 dbh = dbh->b_this_page;
 237         } while (dbh != dbufs);
 238 }
 239
 240 int nilfs_copy_dirty_pages(struct address_space *dmap,
 241                            struct address_space *smap)
 242 {
 243         struct pagevec pvec;
 244         unsigned int i;
 245         pgoff_t index = 0;
 246         int err = 0;
 247
 248         pagevec_init(&pvec);
 249 repeat:
 250         if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY))
 251                 return 0;
 252
 253         for (i = 0; i < pagevec_count(&pvec); i++) {
 254                 struct page *page = pvec.pages[i], *dpage;
 255
 256                 lock_page(page);
 257                 if (unlikely(!PageDirty(page)))
 258                         NILFS_PAGE_BUG(page, "inconsistent dirty state");
 259
 260                 dpage = grab_cache_page(dmap, page->index);
 261                 if (unlikely(!dpage)) {
 262                         /* No empty page is added to the page cache */
 263                         err = -ENOMEM;
 264                         unlock_page(page);
 265                         break;
 266                 }
 267                 if (unlikely(!page_has_buffers(page)))
 268                         NILFS_PAGE_BUG(page,
 269                                        "found empty page in dat page cache");
 270
 271                 nilfs_copy_page(dpage, page, 1);
 272                 __set_page_dirty_nobuffers(dpage);
 273
 274                 unlock_page(dpage);
 275                 put_page(dpage);
 276                 unlock_page(page);
 277         }
 278         pagevec_release(&pvec);
 279         cond_resched();
 280
 281         if (likely(!err))
 282                 goto repeat;
 283         return err;
 284 }
 285
 286 /**
 287  * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
 288  * @dmap: destination page cache
 289  * @smap: source page cache
 290  *
 291  * No pages must be added to the cache during this process.
 292  * This must be ensured by the caller.
 293  */
 294 void nilfs_copy_back_pages(struct address_space *dmap,
 295                            struct address_space *smap)
 296 {
 297         struct folio_batch fbatch;
 298         unsigned int i, n;
 299         pgoff_t start = 0;
 300
 301         folio_batch_init(&fbatch);
 302 repeat:
 303         n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
 304         if (!n)
 305                 return;
 306
 307         for (i = 0; i < folio_batch_count(&fbatch); i++) {
 308                 struct folio *folio = fbatch.folios[i], *dfolio;
 309                 pgoff_t index = folio->index;
 310
 311                 folio_lock(folio);
 312                 dfolio = filemap_lock_folio(dmap, index);
 313                 if (dfolio) {
 314                         /* overwrite existing folio in the destination cache */
 315                         WARN_ON(folio_test_dirty(dfolio));
 316                         nilfs_copy_page(&dfolio->page, &folio->page, 0);
 317                         folio_unlock(dfolio);
 318                         folio_put(dfolio);
 319                         /* Do we not need to remove folio from smap here? */
 320                 } else {
 321                         struct folio *f;
 322
 323                         /* move the folio to the destination cache */
 324                         xa_lock_irq(&smap->i_pages);
 325                         f = __xa_erase(&smap->i_pages, index);
 326                         WARN_ON(folio != f);
 327                         smap->nrpages--;
 328                         xa_unlock_irq(&smap->i_pages);
 329
 330                         xa_lock_irq(&dmap->i_pages);
 331                         f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
 332                         if (unlikely(f)) {
 333                                 /* Probably -ENOMEM */
 334                                 folio->mapping = NULL;
 335                                 folio_put(folio);
 336                         } else {
 337                                 folio->mapping = dmap;
 338                                 dmap->nrpages++;
 339                                 if (folio_test_dirty(folio))
 340                                         __xa_set_mark(&dmap->i_pages, index,
 341                                                         PAGECACHE_TAG_DIRTY);
 342                         }
 343                         xa_unlock_irq(&dmap->i_pages);
 344                 }
 345                 folio_unlock(folio);
 346         }
 347         folio_batch_release(&fbatch);
 348         cond_resched();
 349
 350         goto repeat;
 351 }
 352
 353 /**
 354  * nilfs_clear_dirty_pages - discard dirty pages in address space
 355  * @mapping: address space with dirty pages for discarding
 356  * @silent: suppress [true] or print [false] warning messages
 357  */
 358 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
 359 {
 360         struct pagevec pvec;
 361         unsigned int i;
 362         pgoff_t index = 0;
 363
 364         pagevec_init(&pvec);
 365
 366         while (pagevec_lookup_tag(&pvec, mapping, &index,
 367                                         PAGECACHE_TAG_DIRTY)) {
 368                 for (i = 0; i < pagevec_count(&pvec); i++) {
 369                         struct page *page = pvec.pages[i];
 370
 371                         lock_page(page);
 372                         nilfs_clear_dirty_page(page, silent);
 373                         unlock_page(page);
 374                 }
 375                 pagevec_release(&pvec);
 376                 cond_resched();
 377         }
 378 }
 379
 380 /**
 381  * nilfs_clear_dirty_page - discard dirty page
 382  * @page: dirty page that will be discarded
 383  * @silent: suppress [true] or print [false] warning messages
 384  */
 385 void nilfs_clear_dirty_page(struct page *page, bool silent)
 386 {
 387         struct inode *inode = page->mapping->host;
 388         struct super_block *sb = inode->i_sb;
 389
 390         BUG_ON(!PageLocked(page));
 391
 392         if (!silent)
 393                 nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
 394                            page_offset(page), inode->i_ino);
 395
 396         ClearPageUptodate(page);
 397         ClearPageMappedToDisk(page);
 398
 399         if (page_has_buffers(page)) {
 400                 struct buffer_head *bh, *head;
 401                 const unsigned long clear_bits =
 402                         (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
 403                          BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
 404                          BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
 405
 406                 bh = head = page_buffers(page);
 407                 do {
 408                         lock_buffer(bh);
 409                         if (!silent)
 410                                 nilfs_warn(sb,
 411                                            "discard dirty block: blocknr=%llu, size=%zu",
 412                                            (u64)bh->b_blocknr, bh->b_size);
 413
 414                         set_mask_bits(&bh->b_state, clear_bits, 0);
 415                         unlock_buffer(bh);
 416                 } while (bh = bh->b_this_page, bh != head);
 417         }
 418
 419         __nilfs_clear_page_dirty(page);
 420 }
 421
 422 unsigned int nilfs_page_count_clean_buffers(struct page *page,
 423                                             unsigned int from, unsigned int to)
 424 {
 425         unsigned int block_start, block_end;
 426         struct buffer_head *bh, *head;
 427         unsigned int nc = 0;
 428
 429         for (bh = head = page_buffers(page), block_start = 0;
 430              bh != head || !block_start;
 431              block_start = block_end, bh = bh->b_this_page) {
 432                 block_end = block_start + bh->b_size;
 433                 if (block_end > from && block_start < to && !buffer_dirty(bh))
 434                         nc++;
 435         }
 436         return nc;
 437 }
 438
 439 /*
 440  * NILFS2 needs clear_page_dirty() in the following two cases:
 441  *
 442  * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
 443  *    flag of pages when it copies back pages from shadow cache to the
 444  *    original cache.
 445  *
 446  * 2) Some B-tree operations like insertion or deletion may dispose buffers
 447  *    in dirty state, and this needs to cancel the dirty state of their pages.
 448  */
 449 int __nilfs_clear_page_dirty(struct page *page)
 450 {
 451         struct address_space *mapping = page->mapping;
 452
 453         if (mapping) {
 454                 xa_lock_irq(&mapping->i_pages);
 455                 if (test_bit(PG_dirty, &page->flags)) {
 456                         __xa_clear_mark(&mapping->i_pages, page_index(page),
 457                                              PAGECACHE_TAG_DIRTY);
 458                         xa_unlock_irq(&mapping->i_pages);
 459                         return clear_page_dirty_for_io(page);
 460                 }
 461                 xa_unlock_irq(&mapping->i_pages);
 462                 return 0;
 463         }
 464         return TestClearPageDirty(page);
 465 }
 466
 467 /**
 468  * nilfs_find_uncommitted_extent - find extent of uncommitted data
 469  * @inode: inode
 470  * @start_blk: start block offset (in)
 471  * @blkoff: start offset of the found extent (out)
 472  *
 473  * This function searches an extent of buffers marked "delayed" which
 474  * starts from a block offset equal to or larger than @start_blk.  If
 475  * such an extent was found, this will store the start offset in
 476  * @blkoff and return its length in blocks.  Otherwise, zero is
 477  * returned.
 478  */
 479 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 480                                             sector_t start_blk,
 481                                             sector_t *blkoff)
 482 {
 483         unsigned int i, nr_folios;
 484         pgoff_t index;
 485         unsigned long length = 0;
 486         struct folio_batch fbatch;
 487         struct folio *folio;
 488
 489         if (inode->i_mapping->nrpages == 0)
 490                 return 0;
 491
 492         index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
 493
 494         folio_batch_init(&fbatch);
 495
 496 repeat:
 497         nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
 498                         &fbatch);
 499         if (nr_folios == 0)
 500                 return length;
 501
 502         i = 0;
 503         do {
 504                 folio = fbatch.folios[i];
 505
 506                 folio_lock(folio);
 507                 if (folio_buffers(folio)) {
 508                         struct buffer_head *bh, *head;
 509                         sector_t b;
 510
 511                         b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
 512                         bh = head = folio_buffers(folio);
 513                         do {
 514                                 if (b < start_blk)
 515                                         continue;
 516                                 if (buffer_delay(bh)) {
 517                                         if (length == 0)
 518                                                 *blkoff = b;
 519                                         length++;
 520                                 } else if (length > 0) {
 521                                         goto out_locked;
 522                                 }
 523                         } while (++b, bh = bh->b_this_page, bh != head);
 524                 } else {
 525                         if (length > 0)
 526                                 goto out_locked;
 527                 }
 528                 folio_unlock(folio);
 529
 530         } while (++i < nr_folios);
 531
 532         folio_batch_release(&fbatch);
 533         cond_resched();
 534         goto repeat;
 535
 536 out_locked:
 537         folio_unlock(folio);
 538         folio_batch_release(&fbatch);
 539         return length;
 540 }