git.oblomov.eu Git - linux-2.6/blob - fs/nilfs2/page.c

   1 /*
   2  * page.c - buffer/page management specific to NILFS
   3  *
   4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  * Written by Ryusuke Konishi <ryusuke@osrg.net>,
  21  *            Seiji Kihara <kihara@osrg.net>.
  22  */
  23
  24 #include <linux/pagemap.h>
  25 #include <linux/writeback.h>
  26 #include <linux/swap.h>
  27 #include <linux/bitops.h>
  28 #include <linux/page-flags.h>
  29 #include <linux/list.h>
  30 #include <linux/highmem.h>
  31 #include <linux/pagevec.h>
  32 #include "nilfs.h"
  33 #include "page.h"
  34 #include "mdt.h"
  35
  36
  37 #define NILFS_BUFFER_INHERENT_BITS  \
  38         ((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
  39          (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated))
  40
  41 static struct buffer_head *
  42 __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
  43                        int blkbits, unsigned long b_state)
  44
  45 {
  46         unsigned long first_block;
  47         struct buffer_head *bh;
  48
  49         if (!page_has_buffers(page))
  50                 create_empty_buffers(page, 1 << blkbits, b_state);
  51
  52         first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits);
  53         bh = nilfs_page_get_nth_block(page, block - first_block);
  54
  55         touch_buffer(bh);
  56         wait_on_buffer(bh);
  57         return bh;
  58 }
  59
  60 /*
  61  * Since the page cache of B-tree node pages or data page cache of pseudo
  62  * inodes does not have a valid mapping->host pointer, calling
  63  * mark_buffer_dirty() for their buffers causes a NULL pointer dereference;
  64  * it calls __mark_inode_dirty(NULL) through __set_page_dirty().
  65  * To avoid this problem, the old style mark_buffer_dirty() is used instead.
  66  */
  67 void nilfs_mark_buffer_dirty(struct buffer_head *bh)
  68 {
  69         if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
  70                 __set_page_dirty_nobuffers(bh->b_page);
  71 }
  72
  73 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
  74                                       struct address_space *mapping,
  75                                       unsigned long blkoff,
  76                                       unsigned long b_state)
  77 {
  78         int blkbits = inode->i_blkbits;
  79         pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
  80         struct page *page, *opage;
  81         struct buffer_head *bh, *obh;
  82
  83         page = grab_cache_page(mapping, index);
  84         if (unlikely(!page))
  85                 return NULL;
  86
  87         bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
  88         if (unlikely(!bh)) {
  89                 unlock_page(page);
  90                 page_cache_release(page);
  91                 return NULL;
  92         }
  93         if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) {
  94                 /*
  95                  * Shadow page cache uses assoc_mapping to point its original
  96                  * page cache.  The following code tries the original cache
  97                  * if the given cache is a shadow and it didn't hit.
  98                  */
  99                 opage = find_lock_page(mapping->assoc_mapping, index);
 100                 if (!opage)
 101                         return bh;
 102
 103                 obh = __nilfs_get_page_block(opage, blkoff, index, blkbits,
 104                                              b_state);
 105                 if (buffer_uptodate(obh)) {
 106                         nilfs_copy_buffer(bh, obh);
 107                         if (buffer_dirty(obh)) {
 108                                 nilfs_mark_buffer_dirty(bh);
 109                                 if (!buffer_nilfs_node(bh) && NILFS_MDT(inode))
 110                                         nilfs_mdt_mark_dirty(inode);
 111                         }
 112                 }
 113                 brelse(obh);
 114                 unlock_page(opage);
 115                 page_cache_release(opage);
 116         }
 117         return bh;
 118 }
 119
 120 /**
 121  * nilfs_forget_buffer - discard dirty state
 122  * @inode: owner inode of the buffer
 123  * @bh: buffer head of the buffer to be discarded
 124  */
 125 void nilfs_forget_buffer(struct buffer_head *bh)
 126 {
 127         struct page *page = bh->b_page;
 128
 129         lock_buffer(bh);
 130         clear_buffer_nilfs_volatile(bh);
 131         clear_buffer_dirty(bh);
 132         if (nilfs_page_buffers_clean(page))
 133                 __nilfs_clear_page_dirty(page);
 134
 135         clear_buffer_uptodate(bh);
 136         clear_buffer_mapped(bh);
 137         bh->b_blocknr = -1;
 138         ClearPageUptodate(page);
 139         ClearPageMappedToDisk(page);
 140         unlock_buffer(bh);
 141         brelse(bh);
 142 }
 143
 144 /**
 145  * nilfs_copy_buffer -- copy buffer data and flags
 146  * @dbh: destination buffer
 147  * @sbh: source buffer
 148  */
 149 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
 150 {
 151         void *kaddr0, *kaddr1;
 152         unsigned long bits;
 153         struct page *spage = sbh->b_page, *dpage = dbh->b_page;
 154         struct buffer_head *bh;
 155
 156         kaddr0 = kmap_atomic(spage, KM_USER0);
 157         kaddr1 = kmap_atomic(dpage, KM_USER1);
 158         memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
 159         kunmap_atomic(kaddr1, KM_USER1);
 160         kunmap_atomic(kaddr0, KM_USER0);
 161
 162         dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
 163         dbh->b_blocknr = sbh->b_blocknr;
 164         dbh->b_bdev = sbh->b_bdev;
 165
 166         bh = dbh;
 167         bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
 168         while ((bh = bh->b_this_page) != dbh) {
 169                 lock_buffer(bh);
 170                 bits &= bh->b_state;
 171                 unlock_buffer(bh);
 172         }
 173         if (bits & (1UL << BH_Uptodate))
 174                 SetPageUptodate(dpage);
 175         else
 176                 ClearPageUptodate(dpage);
 177         if (bits & (1UL << BH_Mapped))
 178                 SetPageMappedToDisk(dpage);
 179         else
 180                 ClearPageMappedToDisk(dpage);
 181 }
 182
 183 /**
 184  * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
 185  * @page: page to be checked
 186  *
 187  * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 188  * Otherwise, it returns non-zero value.
 189  */
 190 int nilfs_page_buffers_clean(struct page *page)
 191 {
 192         struct buffer_head *bh, *head;
 193
 194         bh = head = page_buffers(page);
 195         do {
 196                 if (buffer_dirty(bh))
 197                         return 0;
 198                 bh = bh->b_this_page;
 199         } while (bh != head);
 200         return 1;
 201 }
 202
 203 void nilfs_page_bug(struct page *page)
 204 {
 205         struct address_space *m;
 206         unsigned long ino = 0;
 207
 208         if (unlikely(!page)) {
 209                 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
 210                 return;
 211         }
 212
 213         m = page->mapping;
 214         if (m) {
 215                 struct inode *inode = NILFS_AS_I(m);
 216                 if (inode != NULL)
 217                         ino = inode->i_ino;
 218         }
 219         printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 220                "mapping=%p ino=%lu\n",
 221                page, atomic_read(&page->_count),
 222                (unsigned long long)page->index, page->flags, m, ino);
 223
 224         if (page_has_buffers(page)) {
 225                 struct buffer_head *bh, *head;
 226                 int i = 0;
 227
 228                 bh = head = page_buffers(page);
 229                 do {
 230                         printk(KERN_CRIT
 231                                " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
 232                                i++, bh, atomic_read(&bh->b_count),
 233                                (unsigned long long)bh->b_blocknr, bh->b_state);
 234                         bh = bh->b_this_page;
 235                 } while (bh != head);
 236         }
 237 }
 238
 239 /**
 240  * nilfs_alloc_private_page - allocate a private page with buffer heads
 241  *
 242  * Return Value: On success, a pointer to the allocated page is returned.
 243  * On error, NULL is returned.
 244  */
 245 struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
 246                                       unsigned long state)
 247 {
 248         struct buffer_head *bh, *head, *tail;
 249         struct page *page;
 250
 251         page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
 252         if (unlikely(!page))
 253                 return NULL;
 254
 255         lock_page(page);
 256         head = alloc_page_buffers(page, size, 0);
 257         if (unlikely(!head)) {
 258                 unlock_page(page);
 259                 __free_page(page);
 260                 return NULL;
 261         }
 262
 263         bh = head;
 264         do {
 265                 bh->b_state = (1UL << BH_NILFS_Allocated) | state;
 266                 tail = bh;
 267                 bh->b_bdev = bdev;
 268                 bh = bh->b_this_page;
 269         } while (bh);
 270
 271         tail->b_this_page = head;
 272         attach_page_buffers(page, head);
 273
 274         return page;
 275 }
 276
 277 void nilfs_free_private_page(struct page *page)
 278 {
 279         BUG_ON(!PageLocked(page));
 280         BUG_ON(page->mapping);
 281
 282         if (page_has_buffers(page) && !try_to_free_buffers(page))
 283                 NILFS_PAGE_BUG(page, "failed to free page");
 284
 285         unlock_page(page);
 286         __free_page(page);
 287 }
 288
 289 /**
 290  * nilfs_copy_page -- copy the page with buffers
 291  * @dst: destination page
 292  * @src: source page
 293  * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
 294  *
 295  * This fuction is for both data pages and btnode pages.  The dirty flag
 296  * should be treated by caller.  The page must not be under i/o.
 297  * Both src and dst page must be locked
 298  */
 299 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
 300 {
 301         struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
 302         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
 303
 304         BUG_ON(PageWriteback(dst));
 305
 306         sbh = sbufs = page_buffers(src);
 307         if (!page_has_buffers(dst))
 308                 create_empty_buffers(dst, sbh->b_size, 0);
 309
 310         if (copy_dirty)
 311                 mask |= (1UL << BH_Dirty);
 312
 313         dbh = dbufs = page_buffers(dst);
 314         do {
 315                 lock_buffer(sbh);
 316                 lock_buffer(dbh);
 317                 dbh->b_state = sbh->b_state & mask;
 318                 dbh->b_blocknr = sbh->b_blocknr;
 319                 dbh->b_bdev = sbh->b_bdev;
 320                 sbh = sbh->b_this_page;
 321                 dbh = dbh->b_this_page;
 322         } while (dbh != dbufs);
 323
 324         copy_highpage(dst, src);
 325
 326         if (PageUptodate(src) && !PageUptodate(dst))
 327                 SetPageUptodate(dst);
 328         else if (!PageUptodate(src) && PageUptodate(dst))
 329                 ClearPageUptodate(dst);
 330         if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
 331                 SetPageMappedToDisk(dst);
 332         else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
 333                 ClearPageMappedToDisk(dst);
 334
 335         do {
 336                 unlock_buffer(sbh);
 337                 unlock_buffer(dbh);
 338                 sbh = sbh->b_this_page;
 339                 dbh = dbh->b_this_page;
 340         } while (dbh != dbufs);
 341 }
 342
 343 int nilfs_copy_dirty_pages(struct address_space *dmap,
 344                            struct address_space *smap)
 345 {
 346         struct pagevec pvec;
 347         unsigned int i;
 348         pgoff_t index = 0;
 349         int err = 0;
 350
 351         pagevec_init(&pvec, 0);
 352 repeat:
 353         if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
 354                                 PAGEVEC_SIZE))
 355                 return 0;
 356
 357         for (i = 0; i < pagevec_count(&pvec); i++) {
 358                 struct page *page = pvec.pages[i], *dpage;
 359
 360                 lock_page(page);
 361                 if (unlikely(!PageDirty(page)))
 362                         NILFS_PAGE_BUG(page, "inconsistent dirty state");
 363
 364                 dpage = grab_cache_page(dmap, page->index);
 365                 if (unlikely(!dpage)) {
 366                         /* No empty page is added to the page cache */
 367                         err = -ENOMEM;
 368                         unlock_page(page);
 369                         break;
 370                 }
 371                 if (unlikely(!page_has_buffers(page)))
 372                         NILFS_PAGE_BUG(page,
 373                                        "found empty page in dat page cache");
 374
 375                 nilfs_copy_page(dpage, page, 1);
 376                 __set_page_dirty_nobuffers(dpage);
 377
 378                 unlock_page(dpage);
 379                 page_cache_release(dpage);
 380                 unlock_page(page);
 381         }
 382         pagevec_release(&pvec);
 383         cond_resched();
 384
 385         if (likely(!err))
 386                 goto repeat;
 387         return err;
 388 }
 389
 390 /**
 391  * nilfs_copy_back_pages -- copy back pages to orignal cache from shadow cache
 392  * @dmap: destination page cache
 393  * @smap: source page cache
 394  *
 395  * No pages must no be added to the cache during this process.
 396  * This must be ensured by the caller.
 397  */
 398 void nilfs_copy_back_pages(struct address_space *dmap,
 399                            struct address_space *smap)
 400 {
 401         struct pagevec pvec;
 402         unsigned int i, n;
 403         pgoff_t index = 0;
 404         int err;
 405
 406         pagevec_init(&pvec, 0);
 407 repeat:
 408         n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
 409         if (!n)
 410                 return;
 411         index = pvec.pages[n - 1]->index + 1;
 412
 413         for (i = 0; i < pagevec_count(&pvec); i++) {
 414                 struct page *page = pvec.pages[i], *dpage;
 415                 pgoff_t offset = page->index;
 416
 417                 lock_page(page);
 418                 dpage = find_lock_page(dmap, offset);
 419                 if (dpage) {
 420                         /* override existing page on the destination cache */
 421                         WARN_ON(PageDirty(dpage));
 422                         nilfs_copy_page(dpage, page, 0);
 423                         unlock_page(dpage);
 424                         page_cache_release(dpage);
 425                 } else {
 426                         struct page *page2;
 427
 428                         /* move the page to the destination cache */
 429                         spin_lock_irq(&smap->tree_lock);
 430                         page2 = radix_tree_delete(&smap->page_tree, offset);
 431                         WARN_ON(page2 != page);
 432
 433                         smap->nrpages--;
 434                         spin_unlock_irq(&smap->tree_lock);
 435
 436                         spin_lock_irq(&dmap->tree_lock);
 437                         err = radix_tree_insert(&dmap->page_tree, offset, page);
 438                         if (unlikely(err < 0)) {
 439                                 WARN_ON(err == -EEXIST);
 440                                 page->mapping = NULL;
 441                                 page_cache_release(page); /* for cache */
 442                         } else {
 443                                 page->mapping = dmap;
 444                                 dmap->nrpages++;
 445                                 if (PageDirty(page))
 446                                         radix_tree_tag_set(&dmap->page_tree,
 447                                                            offset,
 448                                                            PAGECACHE_TAG_DIRTY);
 449                         }
 450                         spin_unlock_irq(&dmap->tree_lock);
 451                 }
 452                 unlock_page(page);
 453         }
 454         pagevec_release(&pvec);
 455         cond_resched();
 456
 457         goto repeat;
 458 }
 459
 460 void nilfs_clear_dirty_pages(struct address_space *mapping)
 461 {
 462         struct pagevec pvec;
 463         unsigned int i;
 464         pgoff_t index = 0;
 465
 466         pagevec_init(&pvec, 0);
 467
 468         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 469                                   PAGEVEC_SIZE)) {
 470                 for (i = 0; i < pagevec_count(&pvec); i++) {
 471                         struct page *page = pvec.pages[i];
 472                         struct buffer_head *bh, *head;
 473
 474                         lock_page(page);
 475                         ClearPageUptodate(page);
 476                         ClearPageMappedToDisk(page);
 477                         bh = head = page_buffers(page);
 478                         do {
 479                                 lock_buffer(bh);
 480                                 clear_buffer_dirty(bh);
 481                                 clear_buffer_nilfs_volatile(bh);
 482                                 clear_buffer_uptodate(bh);
 483                                 clear_buffer_mapped(bh);
 484                                 unlock_buffer(bh);
 485                                 bh = bh->b_this_page;
 486                         } while (bh != head);
 487
 488                         __nilfs_clear_page_dirty(page);
 489                         unlock_page(page);
 490                 }
 491                 pagevec_release(&pvec);
 492                 cond_resched();
 493         }
 494 }
 495
 496 unsigned nilfs_page_count_clean_buffers(struct page *page,
 497                                         unsigned from, unsigned to)
 498 {
 499         unsigned block_start, block_end;
 500         struct buffer_head *bh, *head;
 501         unsigned nc = 0;
 502
 503         for (bh = head = page_buffers(page), block_start = 0;
 504              bh != head || !block_start;
 505              block_start = block_end, bh = bh->b_this_page) {
 506                 block_end = block_start + bh->b_size;
 507                 if (block_end > from && block_start < to && !buffer_dirty(bh))
 508                         nc++;
 509         }
 510         return nc;
 511 }
 512
 513 /*
 514  * NILFS2 needs clear_page_dirty() in the following two cases:
 515  *
 516  * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
 517  *    page dirty flags when it copies back pages from the shadow cache
 518  *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
 519  *    (dat->{i_mapping,i_btnode_cache}).
 520  *
 521  * 2) Some B-tree operations like insertion or deletion may dispose buffers
 522  *    in dirty state, and this needs to cancel the dirty state of their pages.
 523  */
 524 int __nilfs_clear_page_dirty(struct page *page)
 525 {
 526         struct address_space *mapping = page->mapping;
 527
 528         if (mapping) {
 529                 spin_lock_irq(&mapping->tree_lock);
 530                 if (test_bit(PG_dirty, &page->flags)) {
 531                         radix_tree_tag_clear(&mapping->page_tree,
 532                                              page_index(page),
 533                                              PAGECACHE_TAG_DIRTY);
 534                         spin_unlock_irq(&mapping->tree_lock);
 535                         return clear_page_dirty_for_io(page);
 536                 }
 537                 spin_unlock_irq(&mapping->tree_lock);
 538                 return 0;
 539         }
 540         return TestClearPageDirty(page);
 541 }