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linux/fs/nilfs2/page.h

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nilfs2: buffer and page operations This adds common routines for buffer/page operations used in B-tree node caches, meta data files, or segment constructor (log writer). NILFS uses copy functions for buffers and pages due to the following reasons: 1) Relocation required for COW Since NILFS changes address of on-disk blocks, moving buffers in page cache is needed for the buffers which are not addressed by a file offset. If buffer size is smaller than page size, this involves partial copy of pages. 2) Freezing mmapped pages NILFS calculates checksums for each log to ensure its validity. If page data changes after the checksum calculation, this validity check will not work correctly. To avoid this failure for mmaped pages, NILFS freezes their data by copying. 3) Copy-on-write for DAT pages NILFS makes clones of DAT page caches in a copy-on-write manner during GC processes, and this ensures atomicity and consistency of the DAT in the transient state. In addition, NILFS uses two obsolete functions, nilfs_mark_buffer_dirty() and nilfs_clear_page_dirty() respectively. * nilfs_mark_buffer_dirty() was required to avoid NULL pointer dereference faults: Since the page cache of B-tree node pages or data page cache of pseudo inodes does not have a valid mapping->host, calling mark_buffer_dirty() for their buffers causes the fault; it calls __mark_inode_dirty(NULL) through __set_page_dirty(). * nilfs_clear_page_dirty() was needed in the 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 cloned 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. clear_page_dirty_for_io() caused faults because it does not clear the dirty tag on the page cache. Signed-off-by: Seiji Kihara <kihara.seiji@lab.ntt.co.jp> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-07 02:01:27 +00:00
/*
* page.h - 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>.
*/
#ifndef _NILFS_PAGE_H
#define _NILFS_PAGE_H
#include <linux/buffer_head.h>
#include "nilfs.h"
/*
* Extended buffer state bits
*/
enum {
BH_NILFS_Allocated = BH_PrivateStart,
BH_NILFS_Node,
BH_NILFS_Volatile,
nilfs2: introduce check flag to btree node buffer nilfs_btree_get_block() now may return untested buffer due to read-ahead. This adds a new flag for buffer heads so that the btree code can check whether the buffer is already verified or not. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-07-18 01:42:25 +00:00
BH_NILFS_Checked,
nilfs2: add routines to redirect access to buffers of DAT file During garbage collection (GC), DAT file, which converts virtual block number to real block number, may return disk block number that is not yet written to the device. To avoid access to unwritten blocks, the current implementation stores changes to the caches of GCDAT during GC and atomically commit the changes into the DAT file after they are written to the device. This patch, instead, adds a function that makes a copy of specified buffer and stores it in nilfs_shadow_map, and a function to get the backup copy as needed (nilfs_mdt_freeze_buffer and nilfs_mdt_get_frozen_buffer respectively). Before DAT changes block number in an entry block, it makes a copy and redirect access to the buffer so that address conversion function (i.e. nilfs_dat_translate) refers to the old address saved in the copy. This patch gives requisites for such redirection. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-08-31 02:40:34 +00:00
BH_NILFS_Redirected,
nilfs2: buffer and page operations This adds common routines for buffer/page operations used in B-tree node caches, meta data files, or segment constructor (log writer). NILFS uses copy functions for buffers and pages due to the following reasons: 1) Relocation required for COW Since NILFS changes address of on-disk blocks, moving buffers in page cache is needed for the buffers which are not addressed by a file offset. If buffer size is smaller than page size, this involves partial copy of pages. 2) Freezing mmapped pages NILFS calculates checksums for each log to ensure its validity. If page data changes after the checksum calculation, this validity check will not work correctly. To avoid this failure for mmaped pages, NILFS freezes their data by copying. 3) Copy-on-write for DAT pages NILFS makes clones of DAT page caches in a copy-on-write manner during GC processes, and this ensures atomicity and consistency of the DAT in the transient state. In addition, NILFS uses two obsolete functions, nilfs_mark_buffer_dirty() and nilfs_clear_page_dirty() respectively. * nilfs_mark_buffer_dirty() was required to avoid NULL pointer dereference faults: Since the page cache of B-tree node pages or data page cache of pseudo inodes does not have a valid mapping->host, calling mark_buffer_dirty() for their buffers causes the fault; it calls __mark_inode_dirty(NULL) through __set_page_dirty(). * nilfs_clear_page_dirty() was needed in the 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 cloned 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. clear_page_dirty_for_io() caused faults because it does not clear the dirty tag on the page cache. Signed-off-by: Seiji Kihara <kihara.seiji@lab.ntt.co.jp> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-07 02:01:27 +00:00
};
BUFFER_FNS(NILFS_Allocated, nilfs_allocated) /* nilfs private buffers */
BUFFER_FNS(NILFS_Node, nilfs_node) /* nilfs node buffers */
BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
nilfs2: introduce check flag to btree node buffer nilfs_btree_get_block() now may return untested buffer due to read-ahead. This adds a new flag for buffer heads so that the btree code can check whether the buffer is already verified or not. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-07-18 01:42:25 +00:00
BUFFER_FNS(NILFS_Checked, nilfs_checked) /* buffer is verified */
nilfs2: add routines to redirect access to buffers of DAT file During garbage collection (GC), DAT file, which converts virtual block number to real block number, may return disk block number that is not yet written to the device. To avoid access to unwritten blocks, the current implementation stores changes to the caches of GCDAT during GC and atomically commit the changes into the DAT file after they are written to the device. This patch, instead, adds a function that makes a copy of specified buffer and stores it in nilfs_shadow_map, and a function to get the backup copy as needed (nilfs_mdt_freeze_buffer and nilfs_mdt_get_frozen_buffer respectively). Before DAT changes block number in an entry block, it makes a copy and redirect access to the buffer so that address conversion function (i.e. nilfs_dat_translate) refers to the old address saved in the copy. This patch gives requisites for such redirection. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-08-31 02:40:34 +00:00
BUFFER_FNS(NILFS_Redirected, nilfs_redirected) /* redirected to a copy */
nilfs2: buffer and page operations This adds common routines for buffer/page operations used in B-tree node caches, meta data files, or segment constructor (log writer). NILFS uses copy functions for buffers and pages due to the following reasons: 1) Relocation required for COW Since NILFS changes address of on-disk blocks, moving buffers in page cache is needed for the buffers which are not addressed by a file offset. If buffer size is smaller than page size, this involves partial copy of pages. 2) Freezing mmapped pages NILFS calculates checksums for each log to ensure its validity. If page data changes after the checksum calculation, this validity check will not work correctly. To avoid this failure for mmaped pages, NILFS freezes their data by copying. 3) Copy-on-write for DAT pages NILFS makes clones of DAT page caches in a copy-on-write manner during GC processes, and this ensures atomicity and consistency of the DAT in the transient state. In addition, NILFS uses two obsolete functions, nilfs_mark_buffer_dirty() and nilfs_clear_page_dirty() respectively. * nilfs_mark_buffer_dirty() was required to avoid NULL pointer dereference faults: Since the page cache of B-tree node pages or data page cache of pseudo inodes does not have a valid mapping->host, calling mark_buffer_dirty() for their buffers causes the fault; it calls __mark_inode_dirty(NULL) through __set_page_dirty(). * nilfs_clear_page_dirty() was needed in the 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 cloned 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. clear_page_dirty_for_io() caused faults because it does not clear the dirty tag on the page cache. Signed-off-by: Seiji Kihara <kihara.seiji@lab.ntt.co.jp> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-07 02:01:27 +00:00
void nilfs_mark_buffer_dirty(struct buffer_head *bh);
int __nilfs_clear_page_dirty(struct page *);
struct buffer_head *nilfs_grab_buffer(struct inode *, struct address_space *,
unsigned long, unsigned long);
void nilfs_forget_buffer(struct buffer_head *);
void nilfs_copy_buffer(struct buffer_head *, struct buffer_head *);
int nilfs_page_buffers_clean(struct page *);
void nilfs_page_bug(struct page *);
struct page *nilfs_alloc_private_page(struct block_device *, int,
unsigned long);
void nilfs_free_private_page(struct page *);
int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
void nilfs_copy_back_pages(struct address_space *, struct address_space *);
void nilfs_clear_dirty_pages(struct address_space *);
nilfs2: add routines to roll back state of DAT file This adds optional function to metadata files which makes a copy of bmap, page caches, and b-tree node cache, and rolls back to the copy as needed. This enhancement is intended to displace gcdat inode that provides a similar function in a different way. In this patch, nilfs_shadow_map structure is added to store a copy of the foregoing states. nilfs_mdt_setup_shadow_map relates this structure to a metadata file. And, nilfs_mdt_save_to_shadow_map() and nilfs_mdt_restore_from_shadow_map() provides save and restore functions respectively. Finally, nilfs_mdt_clear_shadow_map() clears states of nilfs_shadow_map. The copy of b-tree node cache and page cache is made by duplicating only dirty pages into corresponding caches in nilfs_shadow_map. Their restoration is done by clearing dirty pages from original caches and by copying dirty pages back from nilfs_shadow_map. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-09-06 03:05:43 +00:00
void nilfs_mapping_init_once(struct address_space *mapping);
void nilfs_mapping_init(struct address_space *mapping,
struct backing_dev_info *bdi,
const struct address_space_operations *aops);
nilfs2: buffer and page operations This adds common routines for buffer/page operations used in B-tree node caches, meta data files, or segment constructor (log writer). NILFS uses copy functions for buffers and pages due to the following reasons: 1) Relocation required for COW Since NILFS changes address of on-disk blocks, moving buffers in page cache is needed for the buffers which are not addressed by a file offset. If buffer size is smaller than page size, this involves partial copy of pages. 2) Freezing mmapped pages NILFS calculates checksums for each log to ensure its validity. If page data changes after the checksum calculation, this validity check will not work correctly. To avoid this failure for mmaped pages, NILFS freezes their data by copying. 3) Copy-on-write for DAT pages NILFS makes clones of DAT page caches in a copy-on-write manner during GC processes, and this ensures atomicity and consistency of the DAT in the transient state. In addition, NILFS uses two obsolete functions, nilfs_mark_buffer_dirty() and nilfs_clear_page_dirty() respectively. * nilfs_mark_buffer_dirty() was required to avoid NULL pointer dereference faults: Since the page cache of B-tree node pages or data page cache of pseudo inodes does not have a valid mapping->host, calling mark_buffer_dirty() for their buffers causes the fault; it calls __mark_inode_dirty(NULL) through __set_page_dirty(). * nilfs_clear_page_dirty() was needed in the 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 cloned 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. clear_page_dirty_for_io() caused faults because it does not clear the dirty tag on the page cache. Signed-off-by: Seiji Kihara <kihara.seiji@lab.ntt.co.jp> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-07 02:01:27 +00:00
unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
#define NILFS_PAGE_BUG(page, m, a...) \
do { nilfs_page_bug(page); BUG(); } while (0)
static inline struct buffer_head *
nilfs_page_get_nth_block(struct page *page, unsigned int count)
{
struct buffer_head *bh = page_buffers(page);
while (count-- > 0)
bh = bh->b_this_page;
get_bh(bh);
return bh;
}
#endif /* _NILFS_PAGE_H */
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