/* * page.c - buffer/page management specific to NILFS * * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * * Written by Ryusuke Konishi <ryusuke@osrg.net>, * Seiji Kihara <kihara@osrg.net>. */ #include <linux/pagemap.h> #include <linux/writeback.h> #include <linux/swap.h> #include <linux/bitops.h> #include <linux/page-flags.h> #include <linux/list.h> #include <linux/highmem.h> #include <linux/pagevec.h> #include "nilfs.h" #include "page.h" #include "mdt.h" #define NILFS_BUFFER_INHERENT_BITS \ ((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \ (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated)) static struct buffer_head * __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index, int blkbits, unsigned long b_state) { unsigned long first_block; struct buffer_head *bh; if (!page_has_buffers(page)) create_empty_buffers(page, 1 << blkbits, b_state); first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits); bh = nilfs_page_get_nth_block(page, block - first_block); touch_buffer(bh); wait_on_buffer(bh); return bh; } /* * Since the page cache of B-tree node pages or data page cache of pseudo * inodes does not have a valid mapping->host pointer, calling * mark_buffer_dirty() for their buffers causes a NULL pointer dereference; * it calls __mark_inode_dirty(NULL) through __set_page_dirty(). * To avoid this problem, the old style mark_buffer_dirty() is used instead. */ void nilfs_mark_buffer_dirty(struct buffer_head *bh) { if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) __set_page_dirty_nobuffers(bh->b_page); } struct buffer_head *nilfs_grab_buffer(struct inode *inode, struct address_space *mapping, unsigned long blkoff, unsigned long b_state) { int blkbits = inode->i_blkbits; pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits); struct page *page, *opage; struct buffer_head *bh, *obh; page = grab_cache_page(mapping, index); if (unlikely(!page)) return NULL; bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state); if (unlikely(!bh)) { unlock_page(page); page_cache_release(page); return NULL; } if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) { /* * Shadow page cache uses assoc_mapping to point its original * page cache. The following code tries the original cache * if the given cache is a shadow and it didn't hit. */ opage = find_lock_page(mapping->assoc_mapping, index); if (!opage) return bh; obh = __nilfs_get_page_block(opage, blkoff, index, blkbits, b_state); if (buffer_uptodate(obh)) { nilfs_copy_buffer(bh, obh); if (buffer_dirty(obh)) { nilfs_mark_buffer_dirty(bh); if (!buffer_nilfs_node(bh) && NILFS_MDT(inode)) nilfs_mdt_mark_dirty(inode); } } brelse(obh); unlock_page(opage); page_cache_release(opage); } return bh; } /** * nilfs_forget_buffer - discard dirty state * @inode: owner inode of the buffer * @bh: buffer head of the buffer to be discarded */ void nilfs_forget_buffer(struct buffer_head *bh) { struct page *page = bh->b_page; lock_buffer(bh); clear_buffer_nilfs_volatile(bh); clear_buffer_dirty(bh); if (nilfs_page_buffers_clean(page)) __nilfs_clear_page_dirty(page); clear_buffer_uptodate(bh); clear_buffer_mapped(bh); bh->b_blocknr = -1; ClearPageUptodate(page); ClearPageMappedToDisk(page); unlock_buffer(bh); brelse(bh); } /** * nilfs_copy_buffer -- copy buffer data and flags * @dbh: destination buffer * @sbh: source buffer */ void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh) { void *kaddr0, *kaddr1; unsigned long bits; struct page *spage = sbh->b_page, *dpage = dbh->b_page; struct buffer_head *bh; kaddr0 = kmap_atomic(spage, KM_USER0); kaddr1 = kmap_atomic(dpage, KM_USER1); memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size); kunmap_atomic(kaddr1, KM_USER1); kunmap_atomic(kaddr0, KM_USER0); dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS; dbh->b_blocknr = sbh->b_blocknr; dbh->b_bdev = sbh->b_bdev; bh = dbh; bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped)); while ((bh = bh->b_this_page) != dbh) { lock_buffer(bh); bits &= bh->b_state; unlock_buffer(bh); } if (bits & (1UL << BH_Uptodate)) SetPageUptodate(dpage); else ClearPageUptodate(dpage); if (bits & (1UL << BH_Mapped)) SetPageMappedToDisk(dpage); else ClearPageMappedToDisk(dpage); } /** * nilfs_page_buffers_clean - check if a page has dirty buffers or not. * @page: page to be checked * * nilfs_page_buffers_clean() returns zero if the page has dirty buffers. * Otherwise, it returns non-zero value. */ int nilfs_page_buffers_clean(struct page *page) { struct buffer_head *bh, *head; bh = head = page_buffers(page); do { if (buffer_dirty(bh)) return 0; bh = bh->b_this_page; } while (bh != head); return 1; } void nilfs_page_bug(struct page *page) { struct address_space *m; unsigned long ino = 0; if (unlikely(!page)) { printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n"); return; } m = page->mapping; if (m) { struct inode *inode = NILFS_AS_I(m); if (inode != NULL) ino = inode->i_ino; } printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx " "mapping=%p ino=%lu\n", page, atomic_read(&page->_count), (unsigned long long)page->index, page->flags, m, ino); if (page_has_buffers(page)) { struct buffer_head *bh, *head; int i = 0; bh = head = page_buffers(page); do { printk(KERN_CRIT " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n", i++, bh, atomic_read(&bh->b_count), (unsigned long long)bh->b_blocknr, bh->b_state); bh = bh->b_this_page; } while (bh != head); } } /** * nilfs_alloc_private_page - allocate a private page with buffer heads * * Return Value: On success, a pointer to the allocated page is returned. * On error, NULL is returned. */ struct page *nilfs_alloc_private_page(struct block_device *bdev, int size, unsigned long state) { struct buffer_head *bh, *head, *tail; struct page *page; page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */ if (unlikely(!page)) return NULL; lock_page(page); head = alloc_page_buffers(page, size, 0); if (unlikely(!head)) { unlock_page(page); __free_page(page); return NULL; } bh = head; do { bh->b_state = (1UL << BH_NILFS_Allocated) | state; tail = bh; bh->b_bdev = bdev; bh = bh->b_this_page; } while (bh); tail->b_this_page = head; attach_page_buffers(page, head); return page; } 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); } /** * nilfs_copy_page -- copy the page with buffers * @dst: destination page * @src: source page * @copy_dirty: flag whether to copy dirty states on the page's buffer heads. * * This fuction is for both data pages and btnode pages. The dirty flag * should be treated by caller. The page must not be under i/o. * Both src and dst page must be locked */ static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty) { struct buffer_head *dbh, *dbufs, *sbh, *sbufs; unsigned long mask = NILFS_BUFFER_INHERENT_BITS; BUG_ON(PageWriteback(dst)); sbh = sbufs = page_buffers(src); if (!page_has_buffers(dst)) create_empty_buffers(dst, sbh->b_size, 0); if (copy_dirty) mask |= (1UL << BH_Dirty); dbh = dbufs = page_buffers(dst); do { lock_buffer(sbh); lock_buffer(dbh); dbh->b_state = sbh->b_state & mask; dbh->b_blocknr = sbh->b_blocknr; dbh->b_bdev = sbh->b_bdev; sbh = sbh->b_this_page; dbh = dbh->b_this_page; } while (dbh != dbufs); copy_highpage(dst, src); if (PageUptodate(src) && !PageUptodate(dst)) SetPageUptodate(dst); else if (!PageUptodate(src) && PageUptodate(dst)) ClearPageUptodate(dst); if (PageMappedToDisk(src) && !PageMappedToDisk(dst)) SetPageMappedToDisk(dst); else if (!PageMappedToDisk(src) && PageMappedToDisk(dst)) ClearPageMappedToDisk(dst); do { unlock_buffer(sbh); unlock_buffer(dbh); sbh = sbh->b_this_page; dbh = dbh->b_this_page; } while (dbh != dbufs); } int nilfs_copy_dirty_pages(struct address_space *dmap, struct address_space *smap) { struct pagevec pvec; unsigned int i; pgoff_t index = 0; int err = 0; pagevec_init(&pvec, 0); repeat: if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY, PAGEVEC_SIZE)) return 0; for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i], *dpage; lock_page(page); if (unlikely(!PageDirty(page))) NILFS_PAGE_BUG(page, "inconsistent dirty state"); dpage = grab_cache_page(dmap, page->index); if (unlikely(!dpage)) { /* No empty page is added to the page cache */ err = -ENOMEM; unlock_page(page); break; } if (unlikely(!page_has_buffers(page))) NILFS_PAGE_BUG(page, "found empty page in dat page cache"); nilfs_copy_page(dpage, page, 1); __set_page_dirty_nobuffers(dpage); unlock_page(dpage); page_cache_release(dpage); unlock_page(page); } pagevec_release(&pvec); cond_resched(); if (likely(!err)) goto repeat; return err; } /** * nilfs_copy_back_pages -- copy back pages to orignal cache from shadow cache * @dmap: destination page cache * @smap: source page cache * * No pages must no be added to the cache during this process. * This must be ensured by the caller. */ void nilfs_copy_back_pages(struct address_space *dmap, struct address_space *smap) { struct pagevec pvec; unsigned int i, n; pgoff_t index = 0; int err; pagevec_init(&pvec, 0); repeat: n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE); if (!n) return; index = pvec.pages[n - 1]->index + 1; for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i], *dpage; pgoff_t offset = page->index; lock_page(page); dpage = find_lock_page(dmap, offset); if (dpage) { /* override existing page on the destination cache */ WARN_ON(PageDirty(dpage)); nilfs_copy_page(dpage, page, 0); unlock_page(dpage); page_cache_release(dpage); } else { struct page *page2; /* move the page to the destination cache */ spin_lock_irq(&smap->tree_lock); page2 = radix_tree_delete(&smap->page_tree, offset); WARN_ON(page2 != page); smap->nrpages--; spin_unlock_irq(&smap->tree_lock); spin_lock_irq(&dmap->tree_lock); err = radix_tree_insert(&dmap->page_tree, offset, page); if (unlikely(err < 0)) { WARN_ON(err == -EEXIST); page->mapping = NULL; page_cache_release(page); /* for cache */ } else { page->mapping = dmap; dmap->nrpages++; if (PageDirty(page)) radix_tree_tag_set(&dmap->page_tree, offset, PAGECACHE_TAG_DIRTY); } spin_unlock_irq(&dmap->tree_lock); } unlock_page(page); } pagevec_release(&pvec); cond_resched(); goto repeat; } void nilfs_clear_dirty_pages(struct address_space *mapping) { struct pagevec pvec; unsigned int i; pgoff_t index = 0; pagevec_init(&pvec, 0); while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY, PAGEVEC_SIZE)) { for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i]; struct buffer_head *bh, *head; lock_page(page); ClearPageUptodate(page); ClearPageMappedToDisk(page); bh = head = page_buffers(page); do { lock_buffer(bh); clear_buffer_dirty(bh); clear_buffer_nilfs_volatile(bh); clear_buffer_uptodate(bh); clear_buffer_mapped(bh); unlock_buffer(bh); bh = bh->b_this_page; } while (bh != head); __nilfs_clear_page_dirty(page); unlock_page(page); } pagevec_release(&pvec); cond_resched(); } } unsigned nilfs_page_count_clean_buffers(struct page *page, unsigned from, unsigned to) { unsigned block_start, block_end; struct buffer_head *bh, *head; unsigned nc = 0; for (bh = head = page_buffers(page), block_start = 0; bh != head || !block_start; block_start = block_end, bh = bh->b_this_page) { block_end = block_start + bh->b_size; if (block_end > from && block_start < to && !buffer_dirty(bh)) nc++; } return nc; } /* * NILFS2 needs clear_page_dirty() in the following two cases: * * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears * page dirty flags when it copies back pages from the shadow cache * (gcdat->{i_mapping,i_btnode_cache}) to its original cache * (dat->{i_mapping,i_btnode_cache}). * * 2) Some B-tree operations like insertion or deletion may dispose buffers * in dirty state, and this needs to cancel the dirty state of their pages. */ int __nilfs_clear_page_dirty(struct page *page) { struct address_space *mapping = page->mapping; if (mapping) { spin_lock_irq(&mapping->tree_lock); if (test_bit(PG_dirty, &page->flags)) { radix_tree_tag_clear(&mapping->page_tree, page_index(page), PAGECACHE_TAG_DIRTY); spin_unlock_irq(&mapping->tree_lock); return clear_page_dirty_for_io(page); } spin_unlock_irq(&mapping->tree_lock); return 0; } return TestClearPageDirty(page); }