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