root/fs/nilfs2/page.c

DEFINITIONS

1. __nilfs_get_page_block
2. nilfs_grab_buffer
3. nilfs_forget_buffer
4. nilfs_copy_buffer
5. nilfs_page_buffers_clean
6. nilfs_page_bug
7. nilfs_copy_page
8. nilfs_copy_dirty_pages
9. nilfs_copy_back_pages
10. nilfs_clear_dirty_pages
11. nilfs_clear_dirty_page
12. nilfs_page_count_clean_buffers
13. nilfs_mapping_init
14. __nilfs_clear_page_dirty
15. nilfs_find_uncommitted_extent

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * page.c - 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  * @inode: owner inode of the buffer
  73  * @bh: buffer head of the buffer to be discarded
  74  */
  75 void nilfs_forget_buffer(struct buffer_head *bh)
  76 {
  77         struct page *page = bh->b_page;
  78         const unsigned long clear_bits =
  79                 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
  80                  BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
  81                  BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
  82 
  83         lock_buffer(bh);
  84         set_mask_bits(&bh->b_state, clear_bits, 0);
  85         if (nilfs_page_buffers_clean(page))
  86                 __nilfs_clear_page_dirty(page);
  87 
  88         bh->b_blocknr = -1;
  89         ClearPageUptodate(page);
  90         ClearPageMappedToDisk(page);
  91         unlock_buffer(bh);
  92         brelse(bh);
  93 }
  94 
  95 /**
  96  * nilfs_copy_buffer -- copy buffer data and flags
  97  * @dbh: destination buffer
  98  * @sbh: source buffer
  99  */
 100 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
 101 {
 102         void *kaddr0, *kaddr1;
 103         unsigned long bits;
 104         struct page *spage = sbh->b_page, *dpage = dbh->b_page;
 105         struct buffer_head *bh;
 106 
 107         kaddr0 = kmap_atomic(spage);
 108         kaddr1 = kmap_atomic(dpage);
 109         memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
 110         kunmap_atomic(kaddr1);
 111         kunmap_atomic(kaddr0);
 112 
 113         dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
 114         dbh->b_blocknr = sbh->b_blocknr;
 115         dbh->b_bdev = sbh->b_bdev;
 116 
 117         bh = dbh;
 118         bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
 119         while ((bh = bh->b_this_page) != dbh) {
 120                 lock_buffer(bh);
 121                 bits &= bh->b_state;
 122                 unlock_buffer(bh);
 123         }
 124         if (bits & BIT(BH_Uptodate))
 125                 SetPageUptodate(dpage);
 126         else
 127                 ClearPageUptodate(dpage);
 128         if (bits & BIT(BH_Mapped))
 129                 SetPageMappedToDisk(dpage);
 130         else
 131                 ClearPageMappedToDisk(dpage);
 132 }
 133 
 134 /**
 135  * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
 136  * @page: page to be checked
 137  *
 138  * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 139  * Otherwise, it returns non-zero value.
 140  */
 141 int nilfs_page_buffers_clean(struct page *page)
 142 {
 143         struct buffer_head *bh, *head;
 144 
 145         bh = head = page_buffers(page);
 146         do {
 147                 if (buffer_dirty(bh))
 148                         return 0;
 149                 bh = bh->b_this_page;
 150         } while (bh != head);
 151         return 1;
 152 }
 153 
 154 void nilfs_page_bug(struct page *page)
 155 {
 156         struct address_space *m;
 157         unsigned long ino;
 158 
 159         if (unlikely(!page)) {
 160                 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
 161                 return;
 162         }
 163 
 164         m = page->mapping;
 165         ino = m ? m->host->i_ino : 0;
 166 
 167         printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 168                "mapping=%p ino=%lu\n",
 169                page, page_ref_count(page),
 170                (unsigned long long)page->index, page->flags, m, ino);
 171 
 172         if (page_has_buffers(page)) {
 173                 struct buffer_head *bh, *head;
 174                 int i = 0;
 175 
 176                 bh = head = page_buffers(page);
 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_page -- copy the page with buffers
 189  * @dst: destination page
 190  * @src: source page
 191  * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
 192  *
 193  * This function is for both data pages and btnode pages.  The dirty flag
 194  * should be treated by caller.  The page must not be under i/o.
 195  * Both src and dst page must be locked
 196  */
 197 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
 198 {
 199         struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
 200         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
 201 
 202         BUG_ON(PageWriteback(dst));
 203 
 204         sbh = sbufs = page_buffers(src);
 205         if (!page_has_buffers(dst))
 206                 create_empty_buffers(dst, sbh->b_size, 0);
 207 
 208         if (copy_dirty)
 209                 mask |= BIT(BH_Dirty);
 210 
 211         dbh = dbufs = page_buffers(dst);
 212         do {
 213                 lock_buffer(sbh);
 214                 lock_buffer(dbh);
 215                 dbh->b_state = sbh->b_state & mask;
 216                 dbh->b_blocknr = sbh->b_blocknr;
 217                 dbh->b_bdev = sbh->b_bdev;
 218                 sbh = sbh->b_this_page;
 219                 dbh = dbh->b_this_page;
 220         } while (dbh != dbufs);
 221 
 222         copy_highpage(dst, src);
 223 
 224         if (PageUptodate(src) && !PageUptodate(dst))
 225                 SetPageUptodate(dst);
 226         else if (!PageUptodate(src) && PageUptodate(dst))
 227                 ClearPageUptodate(dst);
 228         if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
 229                 SetPageMappedToDisk(dst);
 230         else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
 231                 ClearPageMappedToDisk(dst);
 232 
 233         do {
 234                 unlock_buffer(sbh);
 235                 unlock_buffer(dbh);
 236                 sbh = sbh->b_this_page;
 237                 dbh = dbh->b_this_page;
 238         } while (dbh != dbufs);
 239 }
 240 
 241 int nilfs_copy_dirty_pages(struct address_space *dmap,
 242                            struct address_space *smap)
 243 {
 244         struct pagevec pvec;
 245         unsigned int i;
 246         pgoff_t index = 0;
 247         int err = 0;
 248 
 249         pagevec_init(&pvec);
 250 repeat:
 251         if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY))
 252                 return 0;
 253 
 254         for (i = 0; i < pagevec_count(&pvec); i++) {
 255                 struct page *page = pvec.pages[i], *dpage;
 256 
 257                 lock_page(page);
 258                 if (unlikely(!PageDirty(page)))
 259                         NILFS_PAGE_BUG(page, "inconsistent dirty state");
 260 
 261                 dpage = grab_cache_page(dmap, page->index);
 262                 if (unlikely(!dpage)) {
 263                         /* No empty page is added to the page cache */
 264                         err = -ENOMEM;
 265                         unlock_page(page);
 266                         break;
 267                 }
 268                 if (unlikely(!page_has_buffers(page)))
 269                         NILFS_PAGE_BUG(page,
 270                                        "found empty page in dat page cache");
 271 
 272                 nilfs_copy_page(dpage, page, 1);
 273                 __set_page_dirty_nobuffers(dpage);
 274 
 275                 unlock_page(dpage);
 276                 put_page(dpage);
 277                 unlock_page(page);
 278         }
 279         pagevec_release(&pvec);
 280         cond_resched();
 281 
 282         if (likely(!err))
 283                 goto repeat;
 284         return err;
 285 }
 286 
 287 /**
 288  * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
 289  * @dmap: destination page cache
 290  * @smap: source page cache
 291  *
 292  * No pages must be added to the cache during this process.
 293  * This must be ensured by the caller.
 294  */
 295 void nilfs_copy_back_pages(struct address_space *dmap,
 296                            struct address_space *smap)
 297 {
 298         struct pagevec pvec;
 299         unsigned int i, n;
 300         pgoff_t index = 0;
 301 
 302         pagevec_init(&pvec);
 303 repeat:
 304         n = pagevec_lookup(&pvec, smap, &index);
 305         if (!n)
 306                 return;
 307 
 308         for (i = 0; i < pagevec_count(&pvec); i++) {
 309                 struct page *page = pvec.pages[i], *dpage;
 310                 pgoff_t offset = page->index;
 311 
 312                 lock_page(page);
 313                 dpage = find_lock_page(dmap, offset);
 314                 if (dpage) {
 315                         /* overwrite existing page in the destination cache */
 316                         WARN_ON(PageDirty(dpage));
 317                         nilfs_copy_page(dpage, page, 0);
 318                         unlock_page(dpage);
 319                         put_page(dpage);
 320                         /* Do we not need to remove page from smap here? */
 321                 } else {
 322                         struct page *p;
 323 
 324                         /* move the page to the destination cache */
 325                         xa_lock_irq(&smap->i_pages);
 326                         p = __xa_erase(&smap->i_pages, offset);
 327                         WARN_ON(page != p);
 328                         smap->nrpages--;
 329                         xa_unlock_irq(&smap->i_pages);
 330 
 331                         xa_lock_irq(&dmap->i_pages);
 332                         p = __xa_store(&dmap->i_pages, offset, page, GFP_NOFS);
 333                         if (unlikely(p)) {
 334                                 /* Probably -ENOMEM */
 335                                 page->mapping = NULL;
 336                                 put_page(page);
 337                         } else {
 338                                 page->mapping = dmap;
 339                                 dmap->nrpages++;
 340                                 if (PageDirty(page))
 341                                         __xa_set_mark(&dmap->i_pages, offset,
 342                                                         PAGECACHE_TAG_DIRTY);
 343                         }
 344                         xa_unlock_irq(&dmap->i_pages);
 345                 }
 346                 unlock_page(page);
 347         }
 348         pagevec_release(&pvec);
 349         cond_resched();
 350 
 351         goto repeat;
 352 }
 353 
 354 /**
 355  * nilfs_clear_dirty_pages - discard dirty pages in address space
 356  * @mapping: address space with dirty pages for discarding
 357  * @silent: suppress [true] or print [false] warning messages
 358  */
 359 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
 360 {
 361         struct pagevec pvec;
 362         unsigned int i;
 363         pgoff_t index = 0;
 364 
 365         pagevec_init(&pvec);
 366 
 367         while (pagevec_lookup_tag(&pvec, mapping, &index,
 368                                         PAGECACHE_TAG_DIRTY)) {
 369                 for (i = 0; i < pagevec_count(&pvec); i++) {
 370                         struct page *page = pvec.pages[i];
 371 
 372                         lock_page(page);
 373                         nilfs_clear_dirty_page(page, silent);
 374                         unlock_page(page);
 375                 }
 376                 pagevec_release(&pvec);
 377                 cond_resched();
 378         }
 379 }
 380 
 381 /**
 382  * nilfs_clear_dirty_page - discard dirty page
 383  * @page: dirty page that will be discarded
 384  * @silent: suppress [true] or print [false] warning messages
 385  */
 386 void nilfs_clear_dirty_page(struct page *page, bool silent)
 387 {
 388         struct inode *inode = page->mapping->host;
 389         struct super_block *sb = inode->i_sb;
 390 
 391         BUG_ON(!PageLocked(page));
 392 
 393         if (!silent)
 394                 nilfs_msg(sb, KERN_WARNING,
 395                           "discard dirty page: offset=%lld, ino=%lu",
 396                           page_offset(page), inode->i_ino);
 397 
 398         ClearPageUptodate(page);
 399         ClearPageMappedToDisk(page);
 400 
 401         if (page_has_buffers(page)) {
 402                 struct buffer_head *bh, *head;
 403                 const unsigned long clear_bits =
 404                         (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
 405                          BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
 406                          BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
 407 
 408                 bh = head = page_buffers(page);
 409                 do {
 410                         lock_buffer(bh);
 411                         if (!silent)
 412                                 nilfs_msg(sb, KERN_WARNING,
 413                                           "discard dirty block: blocknr=%llu, size=%zu",
 414                                           (u64)bh->b_blocknr, bh->b_size);
 415 
 416                         set_mask_bits(&bh->b_state, clear_bits, 0);
 417                         unlock_buffer(bh);
 418                 } while (bh = bh->b_this_page, bh != head);
 419         }
 420 
 421         __nilfs_clear_page_dirty(page);
 422 }
 423 
 424 unsigned int nilfs_page_count_clean_buffers(struct page *page,
 425                                             unsigned int from, unsigned int to)
 426 {
 427         unsigned int block_start, block_end;
 428         struct buffer_head *bh, *head;
 429         unsigned int nc = 0;
 430 
 431         for (bh = head = page_buffers(page), block_start = 0;
 432              bh != head || !block_start;
 433              block_start = block_end, bh = bh->b_this_page) {
 434                 block_end = block_start + bh->b_size;
 435                 if (block_end > from && block_start < to && !buffer_dirty(bh))
 436                         nc++;
 437         }
 438         return nc;
 439 }
 440 
 441 void nilfs_mapping_init(struct address_space *mapping, struct inode *inode)
 442 {
 443         mapping->host = inode;
 444         mapping->flags = 0;
 445         mapping_set_gfp_mask(mapping, GFP_NOFS);
 446         mapping->private_data = NULL;
 447         mapping->a_ops = &empty_aops;
 448 }
 449 
 450 /*
 451  * NILFS2 needs clear_page_dirty() in the following two cases:
 452  *
 453  * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
 454  *    page dirty flags when it copies back pages from the shadow cache
 455  *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
 456  *    (dat->{i_mapping,i_btnode_cache}).
 457  *
 458  * 2) Some B-tree operations like insertion or deletion may dispose buffers
 459  *    in dirty state, and this needs to cancel the dirty state of their pages.
 460  */
 461 int __nilfs_clear_page_dirty(struct page *page)
 462 {
 463         struct address_space *mapping = page->mapping;
 464 
 465         if (mapping) {
 466                 xa_lock_irq(&mapping->i_pages);
 467                 if (test_bit(PG_dirty, &page->flags)) {
 468                         __xa_clear_mark(&mapping->i_pages, page_index(page),
 469                                              PAGECACHE_TAG_DIRTY);
 470                         xa_unlock_irq(&mapping->i_pages);
 471                         return clear_page_dirty_for_io(page);
 472                 }
 473                 xa_unlock_irq(&mapping->i_pages);
 474                 return 0;
 475         }
 476         return TestClearPageDirty(page);
 477 }
 478 
 479 /**
 480  * nilfs_find_uncommitted_extent - find extent of uncommitted data
 481  * @inode: inode
 482  * @start_blk: start block offset (in)
 483  * @blkoff: start offset of the found extent (out)
 484  *
 485  * This function searches an extent of buffers marked "delayed" which
 486  * starts from a block offset equal to or larger than @start_blk.  If
 487  * such an extent was found, this will store the start offset in
 488  * @blkoff and return its length in blocks.  Otherwise, zero is
 489  * returned.
 490  */
 491 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 492                                             sector_t start_blk,
 493                                             sector_t *blkoff)
 494 {
 495         unsigned int i;
 496         pgoff_t index;
 497         unsigned int nblocks_in_page;
 498         unsigned long length = 0;
 499         sector_t b;
 500         struct pagevec pvec;
 501         struct page *page;
 502 
 503         if (inode->i_mapping->nrpages == 0)
 504                 return 0;
 505 
 506         index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
 507         nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);
 508 
 509         pagevec_init(&pvec);
 510 
 511 repeat:
 512         pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
 513                                         pvec.pages);
 514         if (pvec.nr == 0)
 515                 return length;
 516 
 517         if (length > 0 && pvec.pages[0]->index > index)
 518                 goto out;
 519 
 520         b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
 521         i = 0;
 522         do {
 523                 page = pvec.pages[i];
 524 
 525                 lock_page(page);
 526                 if (page_has_buffers(page)) {
 527                         struct buffer_head *bh, *head;
 528 
 529                         bh = head = page_buffers(page);
 530                         do {
 531                                 if (b < start_blk)
 532                                         continue;
 533                                 if (buffer_delay(bh)) {
 534                                         if (length == 0)
 535                                                 *blkoff = b;
 536                                         length++;
 537                                 } else if (length > 0) {
 538                                         goto out_locked;
 539                                 }
 540                         } while (++b, bh = bh->b_this_page, bh != head);
 541                 } else {
 542                         if (length > 0)
 543                                 goto out_locked;
 544 
 545                         b += nblocks_in_page;
 546                 }
 547                 unlock_page(page);
 548 
 549         } while (++i < pagevec_count(&pvec));
 550 
 551         index = page->index + 1;
 552         pagevec_release(&pvec);
 553         cond_resched();
 554         goto repeat;
 555 
 556 out_locked:
 557         unlock_page(page);
 558 out:
 559         pagevec_release(&pvec);
 560         return length;
 561 }