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_Checked))
  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 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
  62                                       struct address_space *mapping,
  63                                       unsigned long blkoff,
  64                                       unsigned long b_state)
  65 {
  66         int blkbits = inode->i_blkbits;
  67         pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
  68         struct page *page;
  69         struct buffer_head *bh;
  70
  71         page = grab_cache_page(mapping, index);
  72         if (unlikely(!page))
  73                 return NULL;
  74
  75         bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
  76         if (unlikely(!bh)) {
  77                 unlock_page(page);
  78                 page_cache_release(page);
  79                 return NULL;
  80         }
  81         return bh;
  82 }
  83
  84 /**
  85  * nilfs_forget_buffer - discard dirty state
  86  * @inode: owner inode of the buffer
  87  * @bh: buffer head of the buffer to be discarded
  88  */
  89 void nilfs_forget_buffer(struct buffer_head *bh)
  90 {
  91         struct page *page = bh->b_page;
  92
  93         lock_buffer(bh);
  94         clear_buffer_nilfs_volatile(bh);
  95         clear_buffer_nilfs_checked(bh);
  96         clear_buffer_nilfs_redirected(bh);
  97         clear_buffer_dirty(bh);
  98         if (nilfs_page_buffers_clean(page))
  99                 __nilfs_clear_page_dirty(page);
 100
 101         clear_buffer_uptodate(bh);
 102         clear_buffer_mapped(bh);
 103         bh->b_blocknr = -1;
 104         ClearPageUptodate(page);
 105         ClearPageMappedToDisk(page);
 106         unlock_buffer(bh);
 107         brelse(bh);
 108 }
 109
 110 /**
 111  * nilfs_copy_buffer -- copy buffer data and flags
 112  * @dbh: destination buffer
 113  * @sbh: source buffer
 114  */
 115 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
 116 {
 117         void *kaddr0, *kaddr1;
 118         unsigned long bits;
 119         struct page *spage = sbh->b_page, *dpage = dbh->b_page;
 120         struct buffer_head *bh;
 121
 122         kaddr0 = kmap_atomic(spage);
 123         kaddr1 = kmap_atomic(dpage);
 124         memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
 125         kunmap_atomic(kaddr1);
 126         kunmap_atomic(kaddr0);
 127
 128         dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
 129         dbh->b_blocknr = sbh->b_blocknr;
 130         dbh->b_bdev = sbh->b_bdev;
 131
 132         bh = dbh;
 133         bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
 134         while ((bh = bh->b_this_page) != dbh) {
 135                 lock_buffer(bh);
 136                 bits &= bh->b_state;
 137                 unlock_buffer(bh);
 138         }
 139         if (bits & (1UL << BH_Uptodate))
 140                 SetPageUptodate(dpage);
 141         else
 142                 ClearPageUptodate(dpage);
 143         if (bits & (1UL << BH_Mapped))
 144                 SetPageMappedToDisk(dpage);
 145         else
 146                 ClearPageMappedToDisk(dpage);
 147 }
 148
 149 /**
 150  * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
 151  * @page: page to be checked
 152  *
 153  * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 154  * Otherwise, it returns non-zero value.
 155  */
 156 int nilfs_page_buffers_clean(struct page *page)
 157 {
 158         struct buffer_head *bh, *head;
 159
 160         bh = head = page_buffers(page);
 161         do {
 162                 if (buffer_dirty(bh))
 163                         return 0;
 164                 bh = bh->b_this_page;
 165         } while (bh != head);
 166         return 1;
 167 }
 168
 169 void nilfs_page_bug(struct page *page)
 170 {
 171         struct address_space *m;
 172         unsigned long ino;
 173
 174         if (unlikely(!page)) {
 175                 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
 176                 return;
 177         }
 178
 179         m = page->mapping;
 180         ino = m ? m->host->i_ino : 0;
 181
 182         printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 183                "mapping=%p ino=%lu\n",
 184                page, atomic_read(&page->_count),
 185                (unsigned long long)page->index, page->flags, m, ino);
 186
 187         if (page_has_buffers(page)) {
 188                 struct buffer_head *bh, *head;
 189                 int i = 0;
 190
 191                 bh = head = page_buffers(page);
 192                 do {
 193                         printk(KERN_CRIT
 194                                " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
 195                                i++, bh, atomic_read(&bh->b_count),
 196                                (unsigned long long)bh->b_blocknr, bh->b_state);
 197                         bh = bh->b_this_page;
 198                 } while (bh != head);
 199         }
 200 }
 201
 202 /**
 203  * nilfs_copy_page -- copy the page with buffers
 204  * @dst: destination page
 205  * @src: source page
 206  * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
 207  *
 208  * This function is for both data pages and btnode pages.  The dirty flag
 209  * should be treated by caller.  The page must not be under i/o.
 210  * Both src and dst page must be locked
 211  */
 212 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
 213 {
 214         struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
 215         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
 216
 217         BUG_ON(PageWriteback(dst));
 218
 219         sbh = sbufs = page_buffers(src);
 220         if (!page_has_buffers(dst))
 221                 create_empty_buffers(dst, sbh->b_size, 0);
 222
 223         if (copy_dirty)
 224                 mask |= (1UL << BH_Dirty);
 225
 226         dbh = dbufs = page_buffers(dst);
 227         do {
 228                 lock_buffer(sbh);
 229                 lock_buffer(dbh);
 230                 dbh->b_state = sbh->b_state & mask;
 231                 dbh->b_blocknr = sbh->b_blocknr;
 232                 dbh->b_bdev = sbh->b_bdev;
 233                 sbh = sbh->b_this_page;
 234                 dbh = dbh->b_this_page;
 235         } while (dbh != dbufs);
 236
 237         copy_highpage(dst, src);
 238
 239         if (PageUptodate(src) && !PageUptodate(dst))
 240                 SetPageUptodate(dst);
 241         else if (!PageUptodate(src) && PageUptodate(dst))
 242                 ClearPageUptodate(dst);
 243         if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
 244                 SetPageMappedToDisk(dst);
 245         else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
 246                 ClearPageMappedToDisk(dst);
 247
 248         do {
 249                 unlock_buffer(sbh);
 250                 unlock_buffer(dbh);
 251                 sbh = sbh->b_this_page;
 252                 dbh = dbh->b_this_page;
 253         } while (dbh != dbufs);
 254 }
 255
 256 int nilfs_copy_dirty_pages(struct address_space *dmap,
 257                            struct address_space *smap)
 258 {
 259         struct pagevec pvec;
 260         unsigned int i;
 261         pgoff_t index = 0;
 262         int err = 0;
 263
 264         pagevec_init(&pvec, 0);
 265 repeat:
 266         if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
 267                                 PAGEVEC_SIZE))
 268                 return 0;
 269
 270         for (i = 0; i < pagevec_count(&pvec); i++) {
 271                 struct page *page = pvec.pages[i], *dpage;
 272
 273                 lock_page(page);
 274                 if (unlikely(!PageDirty(page)))
 275                         NILFS_PAGE_BUG(page, "inconsistent dirty state");
 276
 277                 dpage = grab_cache_page(dmap, page->index);
 278                 if (unlikely(!dpage)) {
 279                         /* No empty page is added to the page cache */
 280                         err = -ENOMEM;
 281                         unlock_page(page);
 282                         break;
 283                 }
 284                 if (unlikely(!page_has_buffers(page)))
 285                         NILFS_PAGE_BUG(page,
 286                                        "found empty page in dat page cache");
 287
 288                 nilfs_copy_page(dpage, page, 1);
 289                 __set_page_dirty_nobuffers(dpage);
 290
 291                 unlock_page(dpage);
 292                 page_cache_release(dpage);
 293                 unlock_page(page);
 294         }
 295         pagevec_release(&pvec);
 296         cond_resched();
 297
 298         if (likely(!err))
 299                 goto repeat;
 300         return err;
 301 }
 302
 303 /**
 304  * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
 305  * @dmap: destination page cache
 306  * @smap: source page cache
 307  *
 308  * No pages must no be added to the cache during this process.
 309  * This must be ensured by the caller.
 310  */
 311 void nilfs_copy_back_pages(struct address_space *dmap,
 312                            struct address_space *smap)
 313 {
 314         struct pagevec pvec;
 315         unsigned int i, n;
 316         pgoff_t index = 0;
 317         int err;
 318
 319         pagevec_init(&pvec, 0);
 320 repeat:
 321         n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
 322         if (!n)
 323                 return;
 324         index = pvec.pages[n - 1]->index + 1;
 325
 326         for (i = 0; i < pagevec_count(&pvec); i++) {
 327                 struct page *page = pvec.pages[i], *dpage;
 328                 pgoff_t offset = page->index;
 329
 330                 lock_page(page);
 331                 dpage = find_lock_page(dmap, offset);
 332                 if (dpage) {
 333                         /* override existing page on the destination cache */
 334                         WARN_ON(PageDirty(dpage));
 335                         nilfs_copy_page(dpage, page, 0);
 336                         unlock_page(dpage);
 337                         page_cache_release(dpage);
 338                 } else {
 339                         struct page *page2;
 340
 341                         /* move the page to the destination cache */
 342                         spin_lock_irq(&smap->tree_lock);
 343                         page2 = radix_tree_delete(&smap->page_tree, offset);
 344                         WARN_ON(page2 != page);
 345
 346                         smap->nrpages--;
 347                         spin_unlock_irq(&smap->tree_lock);
 348
 349                         spin_lock_irq(&dmap->tree_lock);
 350                         err = radix_tree_insert(&dmap->page_tree, offset, page);
 351                         if (unlikely(err < 0)) {
 352                                 WARN_ON(err == -EEXIST);
 353                                 page->mapping = NULL;
 354                                 page_cache_release(page); /* for cache */
 355                         } else {
 356                                 page->mapping = dmap;
 357                                 dmap->nrpages++;
 358                                 if (PageDirty(page))
 359                                         radix_tree_tag_set(&dmap->page_tree,
 360                                                            offset,
 361                                                            PAGECACHE_TAG_DIRTY);
 362                         }
 363                         spin_unlock_irq(&dmap->tree_lock);
 364                 }
 365                 unlock_page(page);
 366         }
 367         pagevec_release(&pvec);
 368         cond_resched();
 369
 370         goto repeat;
 371 }
 372
 373 void nilfs_clear_dirty_pages(struct address_space *mapping)
 374 {
 375         struct pagevec pvec;
 376         unsigned int i;
 377         pgoff_t index = 0;
 378
 379         pagevec_init(&pvec, 0);
 380
 381         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
 382                                   PAGEVEC_SIZE)) {
 383                 for (i = 0; i < pagevec_count(&pvec); i++) {
 384                         struct page *page = pvec.pages[i];
 385                         struct buffer_head *bh, *head;
 386
 387                         lock_page(page);
 388                         ClearPageUptodate(page);
 389                         ClearPageMappedToDisk(page);
 390                         bh = head = page_buffers(page);
 391                         do {
 392                                 lock_buffer(bh);
 393                                 clear_buffer_dirty(bh);
 394                                 clear_buffer_nilfs_volatile(bh);
 395                                 clear_buffer_nilfs_checked(bh);
 396                                 clear_buffer_nilfs_redirected(bh);
 397                                 clear_buffer_uptodate(bh);
 398                                 clear_buffer_mapped(bh);
 399                                 unlock_buffer(bh);
 400                                 bh = bh->b_this_page;
 401                         } while (bh != head);
 402
 403                         __nilfs_clear_page_dirty(page);
 404                         unlock_page(page);
 405                 }
 406                 pagevec_release(&pvec);
 407                 cond_resched();
 408         }
 409 }
 410
 411 unsigned nilfs_page_count_clean_buffers(struct page *page,
 412                                         unsigned from, unsigned to)
 413 {
 414         unsigned block_start, block_end;
 415         struct buffer_head *bh, *head;
 416         unsigned nc = 0;
 417
 418         for (bh = head = page_buffers(page), block_start = 0;
 419              bh != head || !block_start;
 420              block_start = block_end, bh = bh->b_this_page) {
 421                 block_end = block_start + bh->b_size;
 422                 if (block_end > from && block_start < to && !buffer_dirty(bh))
 423                         nc++;
 424         }
 425         return nc;
 426 }
 427
 428 void nilfs_mapping_init(struct address_space *mapping, struct inode *inode,
 429                         struct backing_dev_info *bdi)
 430 {
 431         mapping->host = inode;
 432         mapping->flags = 0;
 433         mapping_set_gfp_mask(mapping, GFP_NOFS);
 434         mapping->assoc_mapping = NULL;
 435         mapping->backing_dev_info = bdi;
 436         mapping->a_ops = &empty_aops;
 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 the dat/gcdat, NILFS2 clears
 443  *    page dirty flags when it copies back pages from the shadow cache
 444  *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
 445  *    (dat->{i_mapping,i_btnode_cache}).
 446  *
 447  * 2) Some B-tree operations like insertion or deletion may dispose buffers
 448  *    in dirty state, and this needs to cancel the dirty state of their pages.
 449  */
 450 int __nilfs_clear_page_dirty(struct page *page)
 451 {
 452         struct address_space *mapping = page->mapping;
 453
 454         if (mapping) {
 455                 spin_lock_irq(&mapping->tree_lock);
 456                 if (test_bit(PG_dirty, &page->flags)) {
 457                         radix_tree_tag_clear(&mapping->page_tree,
 458                                              page_index(page),
 459                                              PAGECACHE_TAG_DIRTY);
 460                         spin_unlock_irq(&mapping->tree_lock);
 461                         return clear_page_dirty_for_io(page);
 462                 }
 463                 spin_unlock_irq(&mapping->tree_lock);
 464                 return 0;
 465         }
 466         return TestClearPageDirty(page);
 467 }
 468
 469 /**
 470  * nilfs_find_uncommitted_extent - find extent of uncommitted data
 471  * @inode: inode
 472  * @start_blk: start block offset (in)
 473  * @blkoff: start offset of the found extent (out)
 474  *
 475  * This function searches an extent of buffers marked "delayed" which
 476  * starts from a block offset equal to or larger than @start_blk.  If
 477  * such an extent was found, this will store the start offset in
 478  * @blkoff and return its length in blocks.  Otherwise, zero is
 479  * returned.
 480  */
 481 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 482                                             sector_t start_blk,
 483                                             sector_t *blkoff)
 484 {
 485         unsigned int i;
 486         pgoff_t index;
 487         unsigned int nblocks_in_page;
 488         unsigned long length = 0;
 489         sector_t b;
 490         struct pagevec pvec;
 491         struct page *page;
 492
 493         if (inode->i_mapping->nrpages == 0)
 494                 return 0;
 495
 496         index = start_blk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
 497         nblocks_in_page = 1U << (PAGE_CACHE_SHIFT - inode->i_blkbits);
 498
 499         pagevec_init(&pvec, 0);
 500
 501 repeat:
 502         pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
 503                                         pvec.pages);
 504         if (pvec.nr == 0)
 505                 return length;
 506
 507         if (length > 0 && pvec.pages[0]->index > index)
 508                 goto out;
 509
 510         b = pvec.pages[0]->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
 511         i = 0;
 512         do {
 513                 page = pvec.pages[i];
 514
 515                 lock_page(page);
 516                 if (page_has_buffers(page)) {
 517                         struct buffer_head *bh, *head;
 518
 519                         bh = head = page_buffers(page);
 520                         do {
 521                                 if (b < start_blk)
 522                                         continue;
 523                                 if (buffer_delay(bh)) {
 524                                         if (length == 0)
 525                                                 *blkoff = b;
 526                                         length++;
 527                                 } else if (length > 0) {
 528                                         goto out_locked;
 529                                 }
 530                         } while (++b, bh = bh->b_this_page, bh != head);
 531                 } else {
 532                         if (length > 0)
 533                                 goto out_locked;
 534
 535                         b += nblocks_in_page;
 536                 }
 537                 unlock_page(page);
 538
 539         } while (++i < pagevec_count(&pvec));
 540
 541         index = page->index + 1;
 542         pagevec_release(&pvec);
 543         cond_resched();
 544         goto repeat;
 545
 546 out_locked:
 547         unlock_page(page);
 548 out:
 549         pagevec_release(&pvec);
 550         return length;
 551 }