/* * When an ext3-ordered file is truncated, it is possible that many pages are * not successfully freed, because they are attached to a committing transaction. * After the transaction commits, these pages are left on the LRU, with no * ->mapping, and with attached buffers. These pages are trivially reclaimable * by the VM, but their apparent absence upsets the VM accounting, and it makes * the numbers in /proc/meminfo look odd. * * So here, we have a buffer which has just come off the forget list. Look to * see if we can strip all buffers from the backing page. * * Called under journal->j_list_lock. The caller provided us with a ref * against the buffer, and we drop that here. */ static void release_buffer_page(struct buffer_head *bh) { struct page *page; if (buffer_dirty(bh)) goto nope; if (atomic_read(&bh->b_count) != 1) goto nope; page = bh->b_page; if (!page) goto nope; if (page->mapping) goto nope; /* OK, it's a truncated page */ if (!trylock_page(page)) goto nope; page_cache_get(page); __brelse(bh); try_to_free_buffers(page); unlock_page(page); page_cache_release(page); return; nope: __brelse(bh); }
int gfs2_releasepage(struct page *page, gfp_t gfp_mask) { struct address_space *mapping = page->mapping; struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping); struct buffer_head *bh, *head; struct gfs2_bufdata *bd; if (!page_has_buffers(page)) return 0; gfs2_log_lock(sdp); spin_lock(&sdp->sd_ail_lock); head = bh = page_buffers(page); do { if (atomic_read(&bh->b_count)) goto cannot_release; bd = bh->b_private; if (bd && bd->bd_ail) goto cannot_release; if (buffer_pinned(bh) || buffer_dirty(bh)) goto not_possible; bh = bh->b_this_page; } while(bh != head); spin_unlock(&sdp->sd_ail_lock); gfs2_log_unlock(sdp); head = bh = page_buffers(page); do { gfs2_log_lock(sdp); bd = bh->b_private; if (bd) { gfs2_assert_warn(sdp, bd->bd_bh == bh); gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr)); if (!list_empty(&bd->bd_le.le_list)) { if (!buffer_pinned(bh)) list_del_init(&bd->bd_le.le_list); else bd = NULL; } if (bd) bd->bd_bh = NULL; bh->b_private = NULL; } gfs2_log_unlock(sdp); if (bd) kmem_cache_free(gfs2_bufdata_cachep, bd); bh = bh->b_this_page; } while (bh != head); return try_to_free_buffers(page); not_possible: /* Should never happen */ WARN_ON(buffer_dirty(bh)); WARN_ON(buffer_pinned(bh)); cannot_release: spin_unlock(&sdp->sd_ail_lock); gfs2_log_unlock(sdp); return 0; }
void jbd2_journal_invalidatepage(journal_t *journal, struct page *page, unsigned long offset) { struct buffer_head *head, *bh, *next; unsigned int curr_off = 0; int may_free = 1; if (!PageLocked(page)) BUG(); if (!page_has_buffers(page)) return; head = bh = page_buffers(page); do { unsigned int next_off = curr_off + bh->b_size; next = bh->b_this_page; if (offset <= curr_off) { lock_buffer(bh); may_free &= journal_unmap_buffer(journal, bh); unlock_buffer(bh); } curr_off = next_off; bh = next; } while (bh != head); if (!offset) { if (may_free && try_to_free_buffers(page)) J_ASSERT(!page_has_buffers(page)); } }
int jbd2_journal_try_to_free_buffers(journal_t *journal, struct page *page, gfp_t gfp_mask) { struct buffer_head *head; struct buffer_head *bh; int ret = 0; J_ASSERT(PageLocked(page)); head = page_buffers(page); bh = head; do { struct journal_head *jh; jh = jbd2_journal_grab_journal_head(bh); if (!jh) continue; jbd_lock_bh_state(bh); __journal_try_to_free_buffer(journal, bh); jbd2_journal_put_journal_head(jh); jbd_unlock_bh_state(bh); if (buffer_jbd(bh)) goto busy; } while ((bh = bh->b_this_page) != head); ret = try_to_free_buffers(page); busy: return ret; }
void nilfs_free_private_page(struct page *page) { BUG_ON(!PageLocked(page)); BUG_ON(page->mapping); if (page_has_buffers(page) && !try_to_free_buffers(page)) NILFS_PAGE_BUG(page, "failed to free page"); unlock_page(page); __free_page(page); }
int gfs2_releasepage(struct page *page, gfp_t gfp_mask) { struct inode *aspace = page->mapping->host; struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info; struct buffer_head *bh, *head; struct gfs2_bufdata *bd; if (!page_has_buffers(page)) return 0; gfs2_log_lock(sdp); head = bh = page_buffers(page); do { if (atomic_read(&bh->b_count)) goto cannot_release; bd = bh->b_private; if (bd && bd->bd_ail) goto cannot_release; gfs2_assert_warn(sdp, !buffer_pinned(bh)); gfs2_assert_warn(sdp, !buffer_dirty(bh)); bh = bh->b_this_page; } while(bh != head); gfs2_log_unlock(sdp); head = bh = page_buffers(page); do { gfs2_log_lock(sdp); bd = bh->b_private; if (bd) { gfs2_assert_warn(sdp, bd->bd_bh == bh); gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr)); if (!list_empty(&bd->bd_le.le_list)) { if (!buffer_pinned(bh)) list_del_init(&bd->bd_le.le_list); else bd = NULL; } if (bd) bd->bd_bh = NULL; bh->b_private = NULL; } gfs2_log_unlock(sdp); if (bd) kmem_cache_free(gfs2_bufdata_cachep, bd); bh = bh->b_this_page; } while (bh != head); return try_to_free_buffers(page); cannot_release: gfs2_log_unlock(sdp); return 0; }
int gfs2_releasepage(struct page *page, gfp_t gfp_mask) { struct inode *aspace = page->mapping->host; struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info; struct buffer_head *bh, *head; struct gfs2_bufdata *bd; unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ; if (!page_has_buffers(page)) goto out; head = bh = page_buffers(page); do { while (atomic_read(&bh->b_count)) { if (!atomic_read(&aspace->i_writecount)) return 0; if (!(gfp_mask & __GFP_WAIT)) return 0; if (time_after_eq(jiffies, t)) { stuck_releasepage(bh); /* should we withdraw here? */ return 0; } yield(); } gfs2_assert_warn(sdp, !buffer_pinned(bh)); gfs2_assert_warn(sdp, !buffer_dirty(bh)); gfs2_log_lock(sdp); bd = bh->b_private; if (bd) { gfs2_assert_warn(sdp, bd->bd_bh == bh); gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr)); gfs2_assert_warn(sdp, !bd->bd_ail); bd->bd_bh = NULL; if (!list_empty(&bd->bd_le.le_list)) bd = NULL; bh->b_private = NULL; } gfs2_log_unlock(sdp); if (bd) kmem_cache_free(gfs2_bufdata_cachep, bd); bh = bh->b_this_page; } while (bh != head); out: return try_to_free_buffers(page); }
void journal_invalidatepage(journal_t *journal, struct page *page, unsigned long offset) { struct buffer_head *head, *bh, *next; unsigned int curr_off = 0; int may_free = 1; if (!PageLocked(page)) BUG(); if (!page_has_buffers(page)) return; /* We will potentially be playing with lists other than just the * data lists (especially for journaled data mode), so be * cautious in our locking. */ head = bh = page_buffers(page); do { unsigned int next_off = curr_off + bh->b_size; next = bh->b_this_page; if (offset <= curr_off) { /* This block is wholly outside the truncation point */ lock_buffer(bh); may_free &= journal_unmap_buffer(journal, bh); unlock_buffer(bh); } curr_off = next_off; bh = next; } while (bh != head); if (!offset) { if (may_free && try_to_free_buffers(page)) J_ASSERT(!page_has_buffers(page)); } }
int journal_try_to_free_buffers(journal_t *journal, struct page *page, gfp_t gfp_mask) { struct buffer_head *head; struct buffer_head *bh; int ret = 0; J_ASSERT(PageLocked(page)); head = page_buffers(page); bh = head; do { struct journal_head *jh; /* * We take our own ref against the journal_head here to avoid * having to add tons of locking around each instance of * journal_remove_journal_head() and journal_put_journal_head(). */ jh = journal_grab_journal_head(bh); if (!jh) continue; jbd_lock_bh_state(bh); __journal_try_to_free_buffer(journal, bh); journal_put_journal_head(jh); jbd_unlock_bh_state(bh); if (buffer_jbd(bh)) goto busy; } while ((bh = bh->b_this_page) != head); ret = try_to_free_buffers(page); busy: return ret; }
/* * We have our BIO, so we can now mark the buffers clean. Make * sure to only clean buffers which we know we'll be writing. */ static void clean_buffers(struct page *page, unsigned first_unmapped) { unsigned buffer_counter = 0; struct buffer_head *bh, *head; if (!page_has_buffers(page)) return; head = page_buffers(page); bh = head; do { if (buffer_counter++ == first_unmapped) break; clear_buffer_dirty(bh); bh = bh->b_this_page; } while (bh != head); /* * we cannot drop the bh if the page is not uptodate or a concurrent * readpage would fail to serialize with the bh and it would read from * disk before we reach the platter. */ if (buffer_heads_over_limit && PageUptodate(page)) try_to_free_buffers(page); }
/* * For inode and page debug */ int nilfs_releasepage(struct page *page, gfp_t gfp_mask) { struct address_space *mapping = page->mapping; struct inode *inode; int verbose = (nilfs_debug_info.verbose[NILFS_VERBOSE_PAGE] > 1); int ret; if (!verbose && mapping) { inode = NILFS_AS_I(mapping); if (inode->i_sb && !(inode->i_sb->s_flags & MS_ACTIVE)) verbose = 1; } if (unlikely(!PagePrivate(page))) NILFS_PAGE_BUG(page, "no buffers"); if (buffer_nilfs_allocated(page_buffers(page))) NILFS_PAGE_BUG(page, "nilfs allocated page"); /* * Note that non-busy buffer heads may be discarded though the * try_to_free_buffers() call. This may happen when the page is not * dirty, not in writeback, not locked, and belongs to a mapping. * Before changing the state of buffer heads to busy, the page lock * must be held to protect them. */ ret = try_to_free_buffers(page); if (verbose && ret && mapping && mapping->host) { if (page_count(page) > 2 + !PageLRU(page)) /* * This may happen when the other task just happen to * find and get the page during this invalidation. */ PAGE_DEBUG(page, "too many page count"); } return ret; }
int page_launder(int gfp_mask, int sync) { int launder_loop, maxscan, cleaned_pages, maxlaunder; int can_get_io_locks; struct list_head * page_lru; struct page * page; /* * We can only grab the IO locks (eg. for flushing dirty * buffers to disk) if __GFP_IO is set. */ can_get_io_locks = gfp_mask & __GFP_IO; launder_loop = 0; maxlaunder = 0; cleaned_pages = 0; dirty_page_rescan: spin_lock(&pagemap_lru_lock); maxscan = nr_inactive_dirty_pages; while ((page_lru = inactive_dirty_list.prev) != &inactive_dirty_list && maxscan-- > 0) { page = list_entry(page_lru, struct page, lru); /* Wrong page on list?! (list corruption, should not happen) */ if (!PageInactiveDirty(page)) { printk("VM: page_launder, wrong page on list.\n"); list_del(page_lru); nr_inactive_dirty_pages--; page->zone->inactive_dirty_pages--; continue; } /* Page is or was in use? Move it to the active list. */ if (PageTestandClearReferenced(page) || page->age > 0 || (!page->buffers && page_count(page) > 1) || page_ramdisk(page)) { del_page_from_inactive_dirty_list(page); add_page_to_active_list(page); continue; } /* * The page is locked. IO in progress? * Move it to the back of the list. */ if (TryLockPage(page)) { list_del(page_lru); list_add(page_lru, &inactive_dirty_list); continue; } /* * Dirty swap-cache page? Write it out if * last copy.. */ if (PageDirty(page)) { int (*writepage)(struct page *) = page->mapping->a_ops->writepage; int result; if (!writepage) goto page_active; /* First time through? Move it to the back of the list */ if (!launder_loop) { list_del(page_lru); list_add(page_lru, &inactive_dirty_list); UnlockPage(page); continue; } /* OK, do a physical asynchronous write to swap. */ ClearPageDirty(page); page_cache_get(page); spin_unlock(&pagemap_lru_lock); result = writepage(page); page_cache_release(page); /* And re-start the thing.. */ spin_lock(&pagemap_lru_lock); if (result != 1) continue; /* writepage refused to do anything */ set_page_dirty(page); goto page_active; } /* * If the page has buffers, try to free the buffer mappings * associated with this page. If we succeed we either free * the page (in case it was a buffercache only page) or we * move the page to the inactive_clean list. * * On the first round, we should free all previously cleaned * buffer pages */ if (page->buffers) { int wait, clearedbuf; int freed_page = 0; /* * Since we might be doing disk IO, we have to * drop the spinlock and take an extra reference * on the page so it doesn't go away from under us. */ del_page_from_inactive_dirty_list(page); page_cache_get(page); spin_unlock(&pagemap_lru_lock); /* Will we do (asynchronous) IO? */ if (launder_loop && maxlaunder == 0 && sync) wait = 2; /* Synchrounous IO */ else if (launder_loop && maxlaunder-- > 0) wait = 1; /* Async IO */ else wait = 0; /* No IO */ /* Try to free the page buffers. */ clearedbuf = try_to_free_buffers(page, wait); /* * Re-take the spinlock. Note that we cannot * unlock the page yet since we're still * accessing the page_struct here... */ spin_lock(&pagemap_lru_lock); /* The buffers were not freed. */ if (!clearedbuf) { add_page_to_inactive_dirty_list(page); /* The page was only in the buffer cache. */ } else if (!page->mapping) { atomic_dec(&buffermem_pages); freed_page = 1; cleaned_pages++; /* The page has more users besides the cache and us. */ } else if (page_count(page) > 2) { add_page_to_active_list(page); /* OK, we "created" a freeable page. */ } else /* page->mapping && page_count(page) == 2 */ { add_page_to_inactive_clean_list(page); cleaned_pages++; } /* * Unlock the page and drop the extra reference. * We can only do it here because we ar accessing * the page struct above. */ UnlockPage(page); page_cache_release(page); /* * If we're freeing buffer cache pages, stop when * we've got enough free memory. */ if (freed_page && !free_shortage()) break; continue; } else if (page->mapping && !PageDirty(page)) { /* * If a page had an extra reference in * deactivate_page(), we will find it here. * Now the page is really freeable, so we * move it to the inactive_clean list. */ del_page_from_inactive_dirty_list(page); add_page_to_inactive_clean_list(page); UnlockPage(page); cleaned_pages++; } else { page_active: /* * OK, we don't know what to do with the page. * It's no use keeping it here, so we move it to * the active list. */ del_page_from_inactive_dirty_list(page); add_page_to_active_list(page); UnlockPage(page); } } spin_unlock(&pagemap_lru_lock); /* * If we don't have enough free pages, we loop back once * to queue the dirty pages for writeout. When we were called * by a user process (that /needs/ a free page) and we didn't * free anything yet, we wait synchronously on the writeout of * MAX_SYNC_LAUNDER pages. * * We also wake up bdflush, since bdflush should, under most * loads, flush out the dirty pages before we have to wait on * IO. */ if (can_get_io_locks && !launder_loop && free_shortage()) { launder_loop = 1; /* If we cleaned pages, never do synchronous IO. */ if (cleaned_pages) sync = 0; /* We only do a few "out of order" flushes. */ maxlaunder = MAX_LAUNDER; /* Kflushd takes care of the rest. */ wakeup_bdflush(0); goto dirty_page_rescan; } /* Return the number of pages moved to the inactive_clean list. */ return cleaned_pages; }