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>
128 lines
4.4 KiB
C
128 lines
4.4 KiB
C
/*
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* mdt.h - NILFS meta data file prototype and definitions
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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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*/
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#ifndef _NILFS_MDT_H
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#define _NILFS_MDT_H
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#include <linux/buffer_head.h>
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#include <linux/blockgroup_lock.h>
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#include "nilfs.h"
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#include "page.h"
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struct nilfs_shadow_map {
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struct nilfs_bmap_store bmap_store;
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struct address_space frozen_data;
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struct address_space frozen_btnodes;
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struct list_head frozen_buffers;
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};
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/**
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* struct nilfs_mdt_info - on-memory private data of meta data files
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* @mi_nilfs: back pointer to the_nilfs struct
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* @mi_sem: reader/writer semaphore for meta data operations
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* @mi_bgl: per-blockgroup locking
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* @mi_entry_size: size of an entry
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* @mi_first_entry_offset: offset to the first entry
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* @mi_entries_per_block: number of entries in a block
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* @mi_palloc_cache: persistent object allocator cache
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* @mi_shadow: shadow of bmap and page caches
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* @mi_blocks_per_group: number of blocks in a group
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* @mi_blocks_per_desc_block: number of blocks per descriptor block
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*/
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struct nilfs_mdt_info {
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struct the_nilfs *mi_nilfs;
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struct rw_semaphore mi_sem;
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struct blockgroup_lock *mi_bgl;
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unsigned mi_entry_size;
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unsigned mi_first_entry_offset;
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unsigned long mi_entries_per_block;
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struct nilfs_palloc_cache *mi_palloc_cache;
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struct nilfs_shadow_map *mi_shadow;
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unsigned long mi_blocks_per_group;
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unsigned long mi_blocks_per_desc_block;
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};
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static inline struct nilfs_mdt_info *NILFS_MDT(const struct inode *inode)
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{
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return inode->i_private;
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}
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static inline struct the_nilfs *NILFS_I_NILFS(struct inode *inode)
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{
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struct super_block *sb = inode->i_sb;
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return sb ? NILFS_SB(sb)->s_nilfs : NILFS_MDT(inode)->mi_nilfs;
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}
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/* Default GFP flags using highmem */
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#define NILFS_MDT_GFP (__GFP_WAIT | __GFP_IO | __GFP_HIGHMEM)
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int nilfs_mdt_get_block(struct inode *, unsigned long, int,
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void (*init_block)(struct inode *,
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struct buffer_head *, void *),
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struct buffer_head **);
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int nilfs_mdt_delete_block(struct inode *, unsigned long);
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int nilfs_mdt_forget_block(struct inode *, unsigned long);
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int nilfs_mdt_mark_block_dirty(struct inode *, unsigned long);
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int nilfs_mdt_fetch_dirty(struct inode *);
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int nilfs_mdt_init(struct inode *inode, struct the_nilfs *nilfs,
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gfp_t gfp_mask, size_t objsz);
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struct inode *nilfs_mdt_new(struct the_nilfs *, struct super_block *, ino_t,
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size_t);
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struct inode *nilfs_mdt_new_common(struct the_nilfs *, struct super_block *,
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ino_t);
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void nilfs_mdt_destroy(struct inode *);
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void nilfs_mdt_set_entry_size(struct inode *, unsigned, unsigned);
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void nilfs_mdt_set_shadow(struct inode *, struct inode *);
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int nilfs_mdt_setup_shadow_map(struct inode *inode,
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struct nilfs_shadow_map *shadow);
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int nilfs_mdt_save_to_shadow_map(struct inode *inode);
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void nilfs_mdt_restore_from_shadow_map(struct inode *inode);
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void nilfs_mdt_clear_shadow_map(struct inode *inode);
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int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh);
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struct buffer_head *nilfs_mdt_get_frozen_buffer(struct inode *inode,
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struct buffer_head *bh);
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#define nilfs_mdt_mark_buffer_dirty(bh) nilfs_mark_buffer_dirty(bh)
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static inline void nilfs_mdt_mark_dirty(struct inode *inode)
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{
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if (!test_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state))
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set_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state);
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}
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static inline void nilfs_mdt_clear_dirty(struct inode *inode)
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{
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clear_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state);
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}
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static inline __u64 nilfs_mdt_cno(struct inode *inode)
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{
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return NILFS_MDT(inode)->mi_nilfs->ns_cno;
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}
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#define nilfs_mdt_bgl_lock(inode, bg) \
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(&NILFS_MDT(inode)->mi_bgl->locks[(bg) & (NR_BG_LOCKS-1)].lock)
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#endif /* _NILFS_MDT_H */
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