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 <linux/gfp.h>
  33 #include "nilfs.h"
  34 #include "page.h"
  35 #include "mdt.h"
  36
  37
  38 #define NILFS_BUFFER_INHERENT_BITS  \
  39         ((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
  40          (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated))
  41
  42 static struct buffer_head *
  43 __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
  44                        int blkbits, unsigned long b_state)
  45
  46 {
  47         unsigned long first_block;
  48         struct buffer_head *bh;
  49
  50         if (!page_has_buffers(page))
  51                 create_empty_buffers(page, 1 << blkbits, b_state);
  52
  53         first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits);
  54         bh = nilfs_page_get_nth_block(page, block - first_block);
  55
  56         touch_buffer(bh);
  57         wait_on_buffer(bh);
  58         return bh;
  59 }
  60
  61 /*
  62  * Since the page cache of B-tree node pages or data page cache of pseudo
  63  * inodes does not have a valid mapping->host pointer, calling
  64  * mark_buffer_dirty() for their buffers causes a NULL pointer dereference;
  65  * it calls __mark_inode_dirty(NULL) through __set_page_dirty().
  66  * To avoid this problem, the old style mark_buffer_dirty() is used instead.
  67  */
  68 void nilfs_mark_buffer_dirty(struct buffer_head *bh)
  69 {
  70         if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
  71                 __set_page_dirty_nobuffers(bh->b_page);
  72 }
  73
  74 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
  75                                       struct address_space *mapping,
  76                                       unsigned long blkoff,
  77                                       unsigned long b_state)
  78 {
  79         int blkbits = inode->i_blkbits;
  80         pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
  81         struct page *page, *opage;
  82         struct buffer_head *bh, *obh;
  83
  84         page = grab_cache_page(mapping, index);
  85         if (unlikely(!page))
  86                 return NULL;
  87
  88         bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
  89         if (unlikely(!bh)) {
  90                 unlock_page(page);
  91                 page_cache_release(page);
  92                 return NULL;
  93         }
  94         if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) {
  95                 /*
  96                  * Shadow page cache uses assoc_mapping to point its original
  97                  * page cache.  The following code tries the original cache
  98                  * if the given cache is a shadow and it didn't hit.
  99                  */
 100                 opage = find_lock_page(mapping->assoc_mapping, index);
 101                 if (!opage)
 102                         return bh;
 103
 104                 obh = __nilfs_get_page_block(opage, blkoff, index, blkbits,
 105                                              b_state);
 106                 if (buffer_uptodate(obh)) {
 107                         nilfs_copy_buffer(bh, obh);
 108                         if (buffer_dirty(obh)) {
 109                                 nilfs_mark_buffer_dirty(bh);
 110                                 if (!buffer_nilfs_node(bh) && NILFS_MDT(inode))
 111                                         nilfs_mdt_mark_dirty(inode);
 112                         }
 113                 }
 114                 brelse(obh);
 115                 unlock_page(opage);
 116                 page_cache_release(opage);
 117         }
 118         return bh;
 119 }
 120
 121 /**
 122  * nilfs_forget_buffer - discard dirty state
 123  * @inode: owner inode of the buffer
 124  * @bh: buffer head of the buffer to be discarded
 125  */
 126 void nilfs_forget_buffer(struct buffer_head *bh)
 127 {
 128         struct page *page = bh->b_page;
 129
 130         lock_buffer(bh);
 131         clear_buffer_nilfs_volatile(bh);
 132         clear_buffer_dirty(bh);
 133         if (nilfs_page_buffers_clean(page))
 134                 __nilfs_clear_page_dirty(page);
 135
 136         clear_buffer_uptodate(bh);
 137         clear_buffer_mapped(bh);
 138         bh->b_blocknr = -1;
 139         ClearPageUptodate(page);
 140         ClearPageMappedToDisk(page);
 141         unlock_buffer(bh);
 142         brelse(bh);
 143 }
 144
 145 /**
 146  * nilfs_copy_buffer -- copy buffer data and flags
 147  * @dbh: destination buffer
 148  * @sbh: source buffer
 149  */
 150 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
 151 {
 152         void *kaddr0, *kaddr1;
 153         unsigned long bits;
 154         struct page *spage = sbh->b_page, *dpage = dbh->b_page;
 155         struct buffer_head *bh;
 156
 157         kaddr0 = kmap_atomic(spage, KM_USER0);
 158         kaddr1 = kmap_atomic(dpage, KM_USER1);
 159         memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
 160         kunmap_atomic(kaddr1, KM_USER1);
 161         kunmap_atomic(kaddr0, KM_USER0);
 162
 163         dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
 164         dbh->b_blocknr = sbh->b_blocknr;
 165         dbh->b_bdev = sbh->b_bdev;
 166
 167         bh = dbh;
 168         bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
 169         while ((bh = bh->b_this_page) != dbh) {
 170                 lock_buffer(bh);
 171                 bits &= bh->b_state;
 172                 unlock_buffer(bh);
 173         }
 174         if (bits & (1UL << BH_Uptodate))
 175                 SetPageUptodate(dpage);
 176         else
 177                 ClearPageUptodate(dpage);
 178         if (bits & (1UL << BH_Mapped))
 179                 SetPageMappedToDisk(dpage);
 180         else
 181                 ClearPageMappedToDisk(dpage);
 182 }
 183
 184 /**
 185  * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
 186  * @page: page to be checked
 187  *
 188  * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 189  * Otherwise, it returns non-zero value.
 190  */
 191 int nilfs_page_buffers_clean(struct page *page)
 192 {
 193         struct buffer_head *bh, *head;
 194
 195         bh = head = page_buffers(page);
 196         do {
 197                 if (buffer_dirty(bh))
 198                         return 0;
 199                 bh = bh->b_this_page;
 200         } while (bh != head);
 201         return 1;
 202 }
 203
 204 void nilfs_page_bug(struct page *page)
 205 {
 206         struct address_space *m;
 207         unsigned long ino = 0;
 208
 209         if (unlikely(!page)) {
 210                 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
 211                 return;
 212         }
 213
 214         m = page->mapping;
 215         if (m) {
 216                 struct inode *inode = NILFS_AS_I(m);
 217                 if (inode != NULL)
 218                         ino = inode->i_ino;
 219         }
 220         printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 221                "mapping=%p ino=%lu\n",
 222                page, atomic_read(&page->_count),
 223                (unsigned long long)page->index, page->flags, m, ino);
 224
 225         if (page_has_buffers(page)) {
 226                 struct buffer_head *bh, *head;
 227                 int i = 0;
 228
 229                 bh = head = page_buffers(page);
 230                 do {
 231                         printk(KERN_CRIT
 232                                " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
 233                                i++, bh, atomic_read(&bh->b_count),
 234                                (unsigned long long)bh->b_blocknr, bh->b_state);
 235                         bh = bh->b_this_page;
 236                 } while (bh != head);
 237         }
 238 }
 239
 240 /**
 241  * nilfs_alloc_private_page - allocate a private page with buffer heads
 242  *
 243  * Return Value: On success, a pointer to the allocated page is returned.
 244  * On error, NULL is returned.
 245  */
 246 struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
 247                                       unsigned long state)
 248 {
 249         struct buffer_head *bh, *head, *tail;
 250         struct page *page;
 251
 252         page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
 253         if (unlikely(!page))
 254                 return NULL;
 255
 256         lock_page(page);
 257         head = alloc_page_buffers(page, size, 0);
 258         if (unlikely(!head)) {
 259                 unlock_page(page);
 260                 __free_page(page);
 261                 return NULL;
 262         }
 263
 264         bh = head;
 265         do {
 266                 bh->b_state = (1UL << BH_NILFS_Allocated) | state;
 267                 tail = bh;
 268                 bh->b_bdev = bdev;
 269                 bh = bh->b_this_page;
 270         } while (bh);
 271
 272         tail->b_this_page = head;
 273         attach_page_buffers(page, head);
 274
 275         return page;
 276 }
 277
 278 void nilfs_free_private_page(struct page *page)
 279 {
 280         BUG_ON(!PageLocked(page));
 281         BUG_ON(page->mapping);
 282
 283         if (page_has_buffers(page) && !try_to_free_buffers(page))
 284                 NILFS_PAGE_BUG(page, "failed to free page");
 285
 286         unlock_page(page);
 287         __free_page(page);
 288 }
 289
 290 /**
 291  * nilfs_copy_page -- copy the page with buffers
 292  * @dst: destination page
 293  * @src: source page
 294  * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
 295  *
 296  * This function is for both data pages and btnode pages.  The dirty flag
 297  * should be treated by caller.  The page must not be under i/o.
 298  * Both src and dst page must be locked
 299  */
 300 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
 301 {
 302         struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
 303         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
 304
 305         BUG_ON(PageWriteback(dst));
 306
 307         sbh = sbufs = page_buffers(src);
 308         if (!page_has_buffers(dst))
 309                 create_empty_buffers(dst, sbh->b_size, 0);
 310
 311         if (copy_dirty)
 312                 mask |= (1UL << BH_Dirty);
 313
 314         dbh = dbufs = page_buffers(dst);
 315         do {
 316                 lock_buffer(sbh);
 317                 lock_buffer(dbh);
 318                 dbh->b_state = sbh->b_state & mask;
 319                 dbh->b_blocknr = sbh->b_blocknr;
 320                 dbh->b_bdev = sbh->b_bdev;
 321                 sbh = sbh->b_this_page;
 322                 dbh = dbh->b_this_page;
 323         } while (dbh != dbufs);
 324
 325         copy_highpage(dst, src);
 326
 327         if (PageUptodate(src) && !PageUptodate(dst))
 328                 SetPageUptodate(dst);
 329         else if (!PageUptodate(src) && PageUptodate(dst))
 330                 ClearPageUptodate(dst);
 331         if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
 332                 SetPageMappedToDisk(dst);
 333         else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
 334                 ClearPageMappedToDisk(dst);
 335
 336         do {
 337                 unlock_buffer(sbh);
 338                 unlock_buffer(dbh);
 339                 sbh = sbh->b_this_page;
 340                 dbh = dbh->b_this_page;
 341         } while (dbh != dbufs);
 342 }
 343
 344 int nilfs_copy_dirty_pages(struct address_space *dmap,
 345                            struct address_space *smap)
 346 {
 347         struct pagevec pvec;
 348         unsigned int i;
 349         pgoff_t index = 0;
 350         int err = 0;
 351
 352         pagevec_init(&pvec, 0);
 353 repeat:
 354         if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
 355                                 PAGEVEC_SIZE))
 356                 return 0;
 357
 358         for (i = 0; i < pagevec_count(&pvec); i++) {
 359                 struct page *page = pvec.pages[i], *dpage;
 360
 361                 lock_page(page);
 362                 if (unlikely(!PageDirty(page)))
 363                         NILFS_PAGE_BUG(page, "inconsistent dirty state");
 364
 365                 dpage = grab_cache_page(dmap, page->index);
 366                 if (unlikely(!dpage)) {
 367                         /* No empty page is added to the page cache */
 368                         err = -ENOMEM;
 369                         unlock_page(page);
 370                         break;
 371                 }
 372                 if (unlikely(!page_has_buffers(page)))
 373                         NILFS_PAGE_BUG(page,
 374                                        "found empty page in dat page cache");
 375
 376                 nilfs_copy_page(dpage, page, 1);
 377                 __set_page_dirty_nobuffers(dpage);
 378
 379                 unlock_page(dpage);
 380                 page_cache_release(dpage);
 381                 unlock_page(page);
 382         }
 383         pagevec_release(&pvec);
 384         cond_resched();
 385
 386         if (likely(!err))
 387                 goto repeat;
 388         return err;
 389 }
 390
 391 /**
 392  * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
 393  * @dmap: destination page cache
 394  * @smap: source page cache
 395  *
 396  * No pages must no be added to the cache during this process.
 397  * This must be ensured by the caller.
 398  */
 399 void nilfs_copy_back_pages(struct address_space *dmap,
 400                            struct address_space *smap)
 401 {
 402         struct pagevec pvec;
 403         unsigned int i, n;
 404         pgoff_t index = 0;
 405         int err;
 406
 407         pagevec_init(&pvec, 0);
 408 repeat:
 409         n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
 410         if (!n)
 411                 return;
 412         index = pvec.pages[n - 1]->index + 1;
 413
 414         for (i = 0; i < pagevec_count(&pvec); i++) {
 415                 struct page *page = pvec.pages[i], *dpage;
 416                 pgoff_t offset = page->index;
 417
 418                 lock_page(page);
 419                 dpage = find_lock_page(dmap, offset);
 420                 if (dpage) {
 421                         /* override existing page on the destination cache */
 422                         WARN_ON(PageDirty(dpage));
 423                         nilfs_copy_page(dpage, page, 0);
 424                         unlock_page(dpage);
 425                         page_cache_release(dpage);
 426                 } else {
 427                         struct page *page2;
 428
 429                         /* move the page to the destination cache */
 430                         spin_lock_irq(&smap->tree_lock);
 431                         page2 = radix_tree_delete(&smap->page_tree, offset);
 432                         WARN_ON(page2 != page);
 433
 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                                 WARN_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 }