b1f6a4f294
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>
85 lines
2.8 KiB
C
85 lines
2.8 KiB
C
/*
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* page.h - 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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#ifndef _NILFS_PAGE_H
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#define _NILFS_PAGE_H
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#include <linux/buffer_head.h>
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#include "nilfs.h"
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/*
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* Extended buffer state bits
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*/
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enum {
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BH_NILFS_Allocated = BH_PrivateStart,
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BH_NILFS_Node,
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BH_NILFS_Volatile,
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BH_NILFS_Checked,
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BH_NILFS_Redirected,
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};
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BUFFER_FNS(NILFS_Allocated, nilfs_allocated) /* nilfs private buffers */
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BUFFER_FNS(NILFS_Node, nilfs_node) /* nilfs node buffers */
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BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
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BUFFER_FNS(NILFS_Checked, nilfs_checked) /* buffer is verified */
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BUFFER_FNS(NILFS_Redirected, nilfs_redirected) /* redirected to a copy */
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void nilfs_mark_buffer_dirty(struct buffer_head *bh);
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int __nilfs_clear_page_dirty(struct page *);
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struct buffer_head *nilfs_grab_buffer(struct inode *, struct address_space *,
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unsigned long, unsigned long);
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void nilfs_forget_buffer(struct buffer_head *);
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void nilfs_copy_buffer(struct buffer_head *, struct buffer_head *);
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int nilfs_page_buffers_clean(struct page *);
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void nilfs_page_bug(struct page *);
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struct page *nilfs_alloc_private_page(struct block_device *, int,
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unsigned long);
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void nilfs_free_private_page(struct page *);
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int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
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void nilfs_copy_back_pages(struct address_space *, struct address_space *);
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void nilfs_clear_dirty_pages(struct address_space *);
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void nilfs_mapping_init_once(struct address_space *mapping);
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void nilfs_mapping_init(struct address_space *mapping,
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struct backing_dev_info *bdi,
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const struct address_space_operations *aops);
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unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
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#define NILFS_PAGE_BUG(page, m, a...) \
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do { nilfs_page_bug(page); BUG(); } while (0)
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static inline struct buffer_head *
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nilfs_page_get_nth_block(struct page *page, unsigned int count)
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{
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struct buffer_head *bh = page_buffers(page);
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while (count-- > 0)
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bh = bh->b_this_page;
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get_bh(bh);
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return bh;
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}
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#endif /* _NILFS_PAGE_H */
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