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         if (test_clear_buffer_dirty(bh) && nilfs_page_buffers_clean(page))
 132                 __nilfs_clear_page_dirty(page);
 133
 134         clear_buffer_uptodate(bh);
 135         clear_buffer_mapped(bh);
 136         bh->b_blocknr = -1;
 137         ClearPageUptodate(page);
 138         ClearPageMappedToDisk(page);
 139         unlock_buffer(bh);
 140         brelse(bh);
 141 }
 142
 143 /**
 144  * nilfs_copy_buffer -- copy buffer data and flags
 145  * @dbh: destination buffer
 146  * @sbh: source buffer
 147  */
 148 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
 149 {
 150         void *kaddr0, *kaddr1;
 151         unsigned long bits;
 152         struct page *spage = sbh->b_page, *dpage = dbh->b_page;
 153         struct buffer_head *bh;
 154
 155         kaddr0 = kmap_atomic(spage, KM_USER0);
 156         kaddr1 = kmap_atomic(dpage, KM_USER1);
 157         memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
 158         kunmap_atomic(kaddr1, KM_USER1);
 159         kunmap_atomic(kaddr0, KM_USER0);
 160
 161         dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
 162         dbh->b_blocknr = sbh->b_blocknr;
 163         dbh->b_bdev = sbh->b_bdev;
 164
 165         bh = dbh;
 166         bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
 167         while ((bh = bh->b_this_page) != dbh) {
 168                 lock_buffer(bh);
 169                 bits &= bh->b_state;
 170                 unlock_buffer(bh);
 171         }
 172         if (bits & (1UL << BH_Uptodate))
 173                 SetPageUptodate(dpage);
 174         else
 175                 ClearPageUptodate(dpage);
 176         if (bits & (1UL << BH_Mapped))
 177                 SetPageMappedToDisk(dpage);
 178         else
 179                 ClearPageMappedToDisk(dpage);
 180 }
 181
 182 /**
 183  * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
 184  * @page: page to be checked
 185  *
 186  * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 187  * Otherwise, it returns non-zero value.
 188  */
 189 int nilfs_page_buffers_clean(struct page *page)
 190 {
 191         struct buffer_head *bh, *head;
 192
 193         bh = head = page_buffers(page);
 194         do {
 195                 if (buffer_dirty(bh))
 196                         return 0;
 197                 bh = bh->b_this_page;
 198         } while (bh != head);
 199         return 1;
 200 }
 201
 202 void nilfs_page_bug(struct page *page)
 203 {
 204         struct address_space *m;
 205         unsigned long ino = 0;
 206
 207         if (unlikely(!page)) {
 208                 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
 209                 return;
 210         }
 211
 212         m = page->mapping;
 213         if (m) {
 214                 struct inode *inode = NILFS_AS_I(m);
 215                 if (inode != NULL)
 216                         ino = inode->i_ino;
 217         }
 218         printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 219                "mapping=%p ino=%lu\n",
 220                page, atomic_read(&page->_count),
 221                (unsigned long long)page->index, page->flags, m, ino);
 222
 223         if (page_has_buffers(page)) {
 224                 struct buffer_head *bh, *head;
 225                 int i = 0;
 226
 227                 bh = head = page_buffers(page);
 228                 do {
 229                         printk(KERN_CRIT
 230                                " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
 231                                i++, bh, atomic_read(&bh->b_count),
 232                                (unsigned long long)bh->b_blocknr, bh->b_state);
 233                         bh = bh->b_this_page;
 234                 } while (bh != head);
 235         }
 236 }
 237
 238 /**
 239  * nilfs_alloc_private_page - allocate a private page with buffer heads
 240  *
 241  * Return Value: On success, a pointer to the allocated page is returned.
 242  * On error, NULL is returned.
 243  */
 244 struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
 245                                       unsigned long state)
 246 {
 247         struct buffer_head *bh, *head, *tail;
 248         struct page *page;
 249
 250         page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
 251         if (unlikely(!page))
 252                 return NULL;
 253
 254         lock_page(page);
 255         head = alloc_page_buffers(page, size, 0);
 256         if (unlikely(!head)) {
 257                 unlock_page(page);
 258                 __free_page(page);
 259                 return NULL;
 260         }
 261
 262         bh = head;
 263         do {
 264                 bh->b_state = (1UL << BH_NILFS_Allocated) | state;
 265                 tail = bh;
 266                 bh->b_bdev = bdev;
 267                 bh = bh->b_this_page;
 268         } while (bh);
 269
 270         tail->b_this_page = head;
 271         attach_page_buffers(page, head);
 272
 273         return page;
 274 }
 275
 276 void nilfs_free_private_page(struct page *page)
 277 {
 278         BUG_ON(!PageLocked(page));
 279         BUG_ON(page->mapping);
 280
 281         if (page_has_buffers(page) && !try_to_free_buffers(page))
 282                 NILFS_PAGE_BUG(page, "failed to free page");
 283
 284         unlock_page(page);
 285         __free_page(page);
 286 }
 287
 288 /**
 289  * nilfs_copy_page -- copy the page with buffers
 290  * @dst: destination page
 291  * @src: source page
 292  * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
 293  *
 294  * This fuction is for both data pages and btnode pages.  The dirty flag
 295  * should be treated by caller.  The page must not be under i/o.
 296  * Both src and dst page must be locked
 297  */
 298 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
 299 {
 300         struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
 301         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
 302
 303         BUG_ON(PageWriteback(dst));
 304
 305         sbh = sbufs = page_buffers(src);
 306         if (!page_has_buffers(dst))
 307                 create_empty_buffers(dst, sbh->b_size, 0);
 308
 309         if (copy_dirty)
 310                 mask |= (1UL << BH_Dirty);
 311
 312         dbh = dbufs = page_buffers(dst);
 313         do {
 314                 lock_buffer(sbh);
 315                 lock_buffer(dbh);
 316                 dbh->b_state = sbh->b_state & mask;
 317                 dbh->b_blocknr = sbh->b_blocknr;
 318                 dbh->b_bdev = sbh->b_bdev;
 319                 sbh = sbh->b_this_page;
 320                 dbh = dbh->b_this_page;
 321         } while (dbh != dbufs);
 322
 323         copy_highpage(dst, src);
 324
 325         if (PageUptodate(src) && !PageUptodate(dst))
 326                 SetPageUptodate(dst);
 327         else if (!PageUptodate(src) && PageUptodate(dst))
 328                 ClearPageUptodate(dst);
 329         if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
 330                 SetPageMappedToDisk(dst);
 331         else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
 332                 ClearPageMappedToDisk(dst);
 333
 334         do {
 335                 unlock_buffer(sbh);
 336                 unlock_buffer(dbh);
 337                 sbh = sbh->b_this_page;
 338                 dbh = dbh->b_this_page;
 339         } while (dbh != dbufs);
 340 }
 341
 342 int nilfs_copy_dirty_pages(struct address_space *dmap,
 343                            struct address_space *smap)
 344 {
 345         struct pagevec pvec;
 346         unsigned int i;
 347         pgoff_t index = 0;
 348         int err = 0;
 349
 350         pagevec_init(&pvec, 0);
 351 repeat:
 352         if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
 353                                 PAGEVEC_SIZE))
 354                 return 0;
 355
 356         for (i = 0; i < pagevec_count(&pvec); i++) {
 357                 struct page *page = pvec.pages[i], *dpage;
 358
 359                 lock_page(page);
 360                 if (unlikely(!PageDirty(page)))
 361                         NILFS_PAGE_BUG(page, "inconsistent dirty state");
 362
 363                 dpage = grab_cache_page(dmap, page->index);
 364                 if (unlikely(!dpage)) {
 365                         /* No empty page is added to the page cache */
 366                         err = -ENOMEM;
 367                         unlock_page(page);
 368                         break;
 369                 }
 370                 if (unlikely(!page_has_buffers(page)))
 371                         NILFS_PAGE_BUG(page,
 372                                        "found empty page in dat page cache");
 373
 374                 nilfs_copy_page(dpage, page, 1);
 375                 __set_page_dirty_nobuffers(dpage);
 376
 377                 unlock_page(dpage);
 378                 page_cache_release(dpage);
 379                 unlock_page(page);
 380         }
 381         pagevec_release(&pvec);
 382         cond_resched();
 383
 384         if (likely(!err))
 385                 goto repeat;
 386         return err;
 387 }
 388
 389 /**
 390  * nilfs_copy_back_pages -- copy back pages to orignal cache from shadow cache
 391  * @dmap: destination page cache
 392  * @smap: source page cache
 393  *
 394  * No pages must no be added to the cache during this process.
 395  * This must be ensured by the caller.
 396  */
 397 void nilfs_copy_back_pages(struct address_space *dmap,
 398                            struct address_space *smap)
 399 {
 400         struct pagevec pvec;
 401         unsigned int i, n;
 402         pgoff_t index = 0;
 403         int err;
 404
 405         pagevec_init(&pvec, 0);
 406 repeat:
 407         n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
 408         if (!n)
 409                 return;
 410         index = pvec.pages[n - 1]->index + 1;
 411
 412         for (i = 0; i < pagevec_count(&pvec); i++) {
 413                 struct page *page = pvec.pages[i], *dpage;
 414                 pgoff_t offset = page->index;
 415
 416                 lock_page(page);
 417                 dpage = find_lock_page(dmap, offset);
 418                 if (dpage) {
 419                         /* override existing page on the destination cache */
 420                         BUG_ON(PageDirty(dpage));
 421                         nilfs_copy_page(dpage, page, 0);
 422                         unlock_page(dpage);
 423                         page_cache_release(dpage);
 424                 } else {
 425                         struct page *page2;
 426
 427                         /* move the page to the destination cache */
 428                         spin_lock_irq(&smap->tree_lock);
 429                         page2 = radix_tree_delete(&smap->page_tree, offset);
 430                         if (unlikely(page2 != page))
 431                                 NILFS_PAGE_BUG(page, "page removal failed "
 432                                                "(offset=%lu, page2=%p)",
 433                                                offset, page2);
 434                         smap->nrpages--;
 435                         spin_unlock_irq(&smap->tree_lock);
 436
 437                         spin_lock_irq(&dmap->tree_lock);
 438                         err = radix_tree_insert(&dmap->page_tree, offset, page);
 439                         if (unlikely(err < 0)) {
 440                                 BUG_ON(err == -EEXIST);
 441                                 page->mapping = NULL;
 442                                 page_cache_release(page); /* for cache */
 443                         } else {
 444                                 page->mapping = dmap;
 445                                 dmap->nrpages++;
 446                                 if (PageDirty(page))
 447                                         radix_tree_tag_set(&dmap->page_tree,
 448                                                            offset,
 449                                                            PAGECACHE_TAG_DIRTY);
 450                         }
 451                         spin_unlock_irq(&dmap->tree_lock);
 452                 }
 453                 unlock_page(page);
 454         }
 455         pagevec_release(&pvec);
 456         cond_resched();
 457
 458         goto repeat;
 459 }
 460
 461 void nilfs_clear_dirty_pages(struct address_space *mapping)
 462 {
 463         struct pagevec pvec;
 464         unsigned int i;
 465         pgoff_t index = 0;
 466
 467         pagevec_init(&pvec, 0);
 468
 469         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 470                                   PAGEVEC_SIZE)) {
 471                 for (i = 0; i < pagevec_count(&pvec); i++) {
 472                         struct page *page = pvec.pages[i];
 473                         struct buffer_head *bh, *head;
 474
 475                         lock_page(page);
 476                         ClearPageUptodate(page);
 477                         ClearPageMappedToDisk(page);
 478                         bh = head = page_buffers(page);
 479                         do {
 480                                 lock_buffer(bh);
 481                                 clear_buffer_dirty(bh);
 482                                 clear_buffer_nilfs_volatile(bh);
 483                                 clear_buffer_uptodate(bh);
 484                                 clear_buffer_mapped(bh);
 485                                 unlock_buffer(bh);
 486                                 bh = bh->b_this_page;
 487                         } while (bh != head);
 488
 489                         __nilfs_clear_page_dirty(page);
 490                         unlock_page(page);
 491                 }
 492                 pagevec_release(&pvec);
 493                 cond_resched();
 494         }
 495 }
 496
 497 unsigned nilfs_page_count_clean_buffers(struct page *page,
 498                                         unsigned from, unsigned to)
 499 {
 500         unsigned block_start, block_end;
 501         struct buffer_head *bh, *head;
 502         unsigned nc = 0;
 503
 504         for (bh = head = page_buffers(page), block_start = 0;
 505              bh != head || !block_start;
 506              block_start = block_end, bh = bh->b_this_page) {
 507                 block_end = block_start + bh->b_size;
 508                 if (block_end > from && block_start < to && !buffer_dirty(bh))
 509                         nc++;
 510         }
 511         return nc;
 512 }
 513
 514 /*
 515  * NILFS2 needs clear_page_dirty() in the following two cases:
 516  *
 517  * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
 518  *    page dirty flags when it copies back pages from the shadow cache
 519  *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
 520  *    (dat->{i_mapping,i_btnode_cache}).
 521  *
 522  * 2) Some B-tree operations like insertion or deletion may dispose buffers
 523  *    in dirty state, and this needs to cancel the dirty state of their pages.
 524  */
 525 int __nilfs_clear_page_dirty(struct page *page)
 526 {
 527         struct address_space *mapping = page->mapping;
 528
 529         if (mapping) {
 530                 spin_lock_irq(&mapping->tree_lock);
 531                 if (test_bit(PG_dirty, &page->flags)) {
 532                         radix_tree_tag_clear(&mapping->page_tree,
 533                                              page_index(page),
 534                                              PAGECACHE_TAG_DIRTY);
 535                         spin_unlock_irq(&mapping->tree_lock);
 536                         return clear_page_dirty_for_io(page);
 537                 }
 538                 spin_unlock_irq(&mapping->tree_lock);
 539                 return 0;
 540         }
 541         return TestClearPageDirty(page);
 542 }