/* * 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. * * Written by Ryusuke Konishi and Seiji Kihara. */ #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 <linux/gfp.h> #include "nilfs.h" #include "page.h" #include "mdt.h" #define NILFS_BUFFER_INHERENT_BITS \ (BIT(BH_Uptodate) | BIT(BH_Mapped) | BIT(BH_NILFS_Node) | \ BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked)) 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_SHIFT - blkbits); bh = nilfs_page_get_nth_block(page, block - first_block); touch_buffer(bh); wait_on_buffer(bh); return bh; } 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_SHIFT - blkbits); struct page *page; struct buffer_head *bh; 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); put_page(page); return NULL; } 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; const unsigned long clear_bits = (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) | BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected)); lock_buffer(bh); set_mask_bits(&bh->b_state, clear_bits, 0); if (nilfs_page_buffers_clean(page)) __nilfs_clear_page_dirty(page); 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); kaddr1 = kmap_atomic(dpage); memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size); kunmap_atomic(kaddr1); kunmap_atomic(kaddr0); 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 & (BIT(BH_Uptodate) | BIT(BH_Mapped)); while ((bh = bh->b_this_page) != dbh) { lock_buffer(bh); bits &= bh->b_state; unlock_buffer(bh); } if (bits & BIT(BH_Uptodate)) SetPageUptodate(dpage); else ClearPageUptodate(dpage); if (bits & BIT(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; if (unlikely(!page)) { printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n"); return; } m = page->mapping; ino = m ? m->host->i_ino : 0; printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx " "mapping=%p ino=%lu\n", page, page_ref_count(page), (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_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 function 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 |= BIT(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); repeat: if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY)) 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); put_page(dpage); unlock_page(page); } pagevec_release(&pvec); cond_resched(); if (likely(!err)) goto repeat; return err; } /** * nilfs_copy_back_pages -- copy back pages to original 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); repeat: n = pagevec_lookup(&pvec, smap, &index); if (!n) return; 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); put_page(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; put_page(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; } /** * nilfs_clear_dirty_pages - discard dirty pages in address space * @mapping: address space with dirty pages for discarding * @silent: suppress [true] or print [false] warning messages */ void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent) { struct pagevec pvec; unsigned int i; pgoff_t index = 0; pagevec_init(&pvec); while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY)) { for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i]; lock_page(page); nilfs_clear_dirty_page(page, silent); unlock_page(page); } pagevec_release(&pvec); cond_resched(); } } /** * nilfs_clear_dirty_page - discard dirty page * @page: dirty page that will be discarded * @silent: suppress [true] or print [false] warning messages */ void nilfs_clear_dirty_page(struct page *page, bool silent) { struct inode *inode = page->mapping->host; struct super_block *sb = inode->i_sb; BUG_ON(!PageLocked(page)); if (!silent) nilfs_msg(sb, KERN_WARNING, "discard dirty page: offset=%lld, ino=%lu", page_offset(page), inode->i_ino); ClearPageUptodate(page); ClearPageMappedToDisk(page); if (page_has_buffers(page)) { struct buffer_head *bh, *head; const unsigned long clear_bits = (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) | BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected)); bh = head = page_buffers(page); do { lock_buffer(bh); if (!silent) nilfs_msg(sb, KERN_WARNING, "discard dirty block: blocknr=%llu, size=%zu", (u64)bh->b_blocknr, bh->b_size); set_mask_bits(&bh->b_state, clear_bits, 0); unlock_buffer(bh); } while (bh = bh->b_this_page, bh != head); } __nilfs_clear_page_dirty(page); } unsigned int nilfs_page_count_clean_buffers(struct page *page, unsigned int from, unsigned int to) { unsigned int block_start, block_end; struct buffer_head *bh, *head; unsigned int 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; } void nilfs_mapping_init(struct address_space *mapping, struct inode *inode) { mapping->host = inode; mapping->flags = 0; mapping_set_gfp_mask(mapping, GFP_NOFS); mapping->private_data = NULL; mapping->a_ops = &empty_aops; } /* * 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); } /** * nilfs_find_uncommitted_extent - find extent of uncommitted data * @inode: inode * @start_blk: start block offset (in) * @blkoff: start offset of the found extent (out) * * This function searches an extent of buffers marked "delayed" which * starts from a block offset equal to or larger than @start_blk. If * such an extent was found, this will store the start offset in * @blkoff and return its length in blocks. Otherwise, zero is * returned. */ unsigned long nilfs_find_uncommitted_extent(struct inode *inode, sector_t start_blk, sector_t *blkoff) { unsigned int i; pgoff_t index; unsigned int nblocks_in_page; unsigned long length = 0; sector_t b; struct pagevec pvec; struct page *page; if (inode->i_mapping->nrpages == 0) return 0; index = start_blk >> (PAGE_SHIFT - inode->i_blkbits); nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits); pagevec_init(&pvec); repeat: pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE, pvec.pages); if (pvec.nr == 0) return length; if (length > 0 && pvec.pages[0]->index > index) goto out; b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits); i = 0; do { page = pvec.pages[i]; lock_page(page); if (page_has_buffers(page)) { struct buffer_head *bh, *head; bh = head = page_buffers(page); do { if (b < start_blk) continue; if (buffer_delay(bh)) { if (length == 0) *blkoff = b; length++; } else if (length > 0) { goto out_locked; } } while (++b, bh = bh->b_this_page, bh != head); } else { if (length > 0) goto out_locked; b += nblocks_in_page; } unlock_page(page); } while (++i < pagevec_count(&pvec)); index = page->index + 1; pagevec_release(&pvec); cond_resched(); goto repeat; out_locked: unlock_page(page); out: pagevec_release(&pvec); return length; }