7ef3ff2fea
Nilfs2 eventually hangs in a stress test with fsstress program. This
issue was caused by the following deadlock over I_SYNC flag between
nilfs_segctor_thread() and writeback_sb_inodes():
nilfs_segctor_thread()
nilfs_segctor_thread_construct()
nilfs_segctor_unlock()
nilfs_dispose_list()
iput()
iput_final()
evict()
inode_wait_for_writeback() * wait for I_SYNC flag
writeback_sb_inodes()
* set I_SYNC flag on inode->i_state
__writeback_single_inode()
do_writepages()
nilfs_writepages()
nilfs_construct_dsync_segment()
nilfs_segctor_sync()
* wait for completion of segment constructor
inode_sync_complete()
* clear I_SYNC flag after __writeback_single_inode() completed
writeback_sb_inodes() calls do_writepages() for dirty inodes after
setting I_SYNC flag on inode->i_state. do_writepages() in turn calls
nilfs_writepages(), which can run segment constructor and wait for its
completion. On the other hand, segment constructor calls iput(), which
can call evict() and wait for the I_SYNC flag on
inode_wait_for_writeback().
Since segment constructor doesn't know when I_SYNC will be set, it
cannot know whether iput() will block or not unless inode->i_nlink has a
non-zero count. We can prevent evict() from being called in iput() by
implementing sop->drop_inode(), but it's not preferable to leave inodes
with i_nlink == 0 for long periods because it even defers file
truncation and inode deallocation. So, this instead resolves the
deadlock by calling iput() asynchronously with a workqueue for inodes
with i_nlink == 0.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
251 lines
8.3 KiB
C
251 lines
8.3 KiB
C
/*
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* segment.h - NILFS Segment constructor prototypes 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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*/
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#ifndef _NILFS_SEGMENT_H
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#define _NILFS_SEGMENT_H
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/workqueue.h>
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#include <linux/nilfs2_fs.h>
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#include "nilfs.h"
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struct nilfs_root;
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/**
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* struct nilfs_recovery_info - Recovery information
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* @ri_need_recovery: Recovery status
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* @ri_super_root: Block number of the last super root
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* @ri_ri_cno: Number of the last checkpoint
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* @ri_lsegs_start: Region for roll-forwarding (start block number)
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* @ri_lsegs_end: Region for roll-forwarding (end block number)
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* @ri_lseg_start_seq: Sequence value of the segment at ri_lsegs_start
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* @ri_used_segments: List of segments to be mark active
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* @ri_pseg_start: Block number of the last partial segment
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* @ri_seq: Sequence number on the last partial segment
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* @ri_segnum: Segment number on the last partial segment
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* @ri_nextnum: Next segment number on the last partial segment
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*/
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struct nilfs_recovery_info {
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int ri_need_recovery;
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sector_t ri_super_root;
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__u64 ri_cno;
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sector_t ri_lsegs_start;
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sector_t ri_lsegs_end;
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u64 ri_lsegs_start_seq;
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struct list_head ri_used_segments;
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sector_t ri_pseg_start;
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u64 ri_seq;
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__u64 ri_segnum;
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__u64 ri_nextnum;
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};
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/* ri_need_recovery */
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#define NILFS_RECOVERY_SR_UPDATED 1 /* The super root was updated */
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#define NILFS_RECOVERY_ROLLFORWARD_DONE 2 /* Rollforward was carried out */
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/**
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* struct nilfs_cstage - Context of collection stage
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* @scnt: Stage count
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* @flags: State flags
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* @dirty_file_ptr: Pointer on dirty_files list, or inode of a target file
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* @gc_inode_ptr: Pointer on the list of gc-inodes
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*/
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struct nilfs_cstage {
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int scnt;
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unsigned flags;
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struct nilfs_inode_info *dirty_file_ptr;
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struct nilfs_inode_info *gc_inode_ptr;
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};
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struct nilfs_segment_buffer;
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struct nilfs_segsum_pointer {
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struct buffer_head *bh;
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unsigned offset; /* offset in bytes */
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};
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/**
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* struct nilfs_sc_info - Segment constructor information
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* @sc_super: Back pointer to super_block struct
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* @sc_root: root object of the current filesystem tree
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* @sc_nblk_inc: Block count of current generation
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* @sc_dirty_files: List of files to be written
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* @sc_gc_inodes: List of GC inodes having blocks to be written
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* @sc_iput_queue: list of inodes for which iput should be done
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* @sc_iput_work: work struct to defer iput call
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* @sc_freesegs: array of segment numbers to be freed
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* @sc_nfreesegs: number of segments on @sc_freesegs
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* @sc_dsync_inode: inode whose data pages are written for a sync operation
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* @sc_dsync_start: start byte offset of data pages
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* @sc_dsync_end: end byte offset of data pages (inclusive)
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* @sc_segbufs: List of segment buffers
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* @sc_write_logs: List of segment buffers to hold logs under writing
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* @sc_segbuf_nblocks: Number of available blocks in segment buffers.
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* @sc_curseg: Current segment buffer
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* @sc_stage: Collection stage
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* @sc_finfo_ptr: pointer to the current finfo struct in the segment summary
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* @sc_binfo_ptr: pointer to the current binfo struct in the segment summary
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* @sc_blk_cnt: Block count of a file
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* @sc_datablk_cnt: Data block count of a file
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* @sc_nblk_this_inc: Number of blocks included in the current logical segment
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* @sc_seg_ctime: Creation time
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* @sc_cno: checkpoint number of current log
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* @sc_flags: Internal flags
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* @sc_state_lock: spinlock for sc_state and so on
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* @sc_state: Segctord state flags
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* @sc_flush_request: inode bitmap of metadata files to be flushed
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* @sc_wait_request: Client request queue
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* @sc_wait_daemon: Daemon wait queue
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* @sc_wait_task: Start/end wait queue to control segctord task
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* @sc_seq_request: Request counter
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* @sc_seq_accept: Accepted request count
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* @sc_seq_done: Completion counter
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* @sc_sync: Request of explicit sync operation
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* @sc_interval: Timeout value of background construction
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* @sc_mjcp_freq: Frequency of creating checkpoints
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* @sc_lseg_stime: Start time of the latest logical segment
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* @sc_watermark: Watermark for the number of dirty buffers
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* @sc_timer: Timer for segctord
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* @sc_task: current thread of segctord
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*/
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struct nilfs_sc_info {
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struct super_block *sc_super;
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struct nilfs_root *sc_root;
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unsigned long sc_nblk_inc;
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struct list_head sc_dirty_files;
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struct list_head sc_gc_inodes;
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struct list_head sc_iput_queue;
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struct work_struct sc_iput_work;
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__u64 *sc_freesegs;
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size_t sc_nfreesegs;
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struct nilfs_inode_info *sc_dsync_inode;
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loff_t sc_dsync_start;
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loff_t sc_dsync_end;
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/* Segment buffers */
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struct list_head sc_segbufs;
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struct list_head sc_write_logs;
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unsigned long sc_segbuf_nblocks;
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struct nilfs_segment_buffer *sc_curseg;
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struct nilfs_cstage sc_stage;
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struct nilfs_segsum_pointer sc_finfo_ptr;
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struct nilfs_segsum_pointer sc_binfo_ptr;
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unsigned long sc_blk_cnt;
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unsigned long sc_datablk_cnt;
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unsigned long sc_nblk_this_inc;
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time_t sc_seg_ctime;
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__u64 sc_cno;
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unsigned long sc_flags;
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spinlock_t sc_state_lock;
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unsigned long sc_state;
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unsigned long sc_flush_request;
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wait_queue_head_t sc_wait_request;
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wait_queue_head_t sc_wait_daemon;
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wait_queue_head_t sc_wait_task;
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__u32 sc_seq_request;
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__u32 sc_seq_accepted;
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__u32 sc_seq_done;
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int sc_sync;
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unsigned long sc_interval;
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unsigned long sc_mjcp_freq;
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unsigned long sc_lseg_stime; /* in 1/HZ seconds */
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unsigned long sc_watermark;
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struct timer_list sc_timer;
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struct task_struct *sc_task;
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};
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/* sc_flags */
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enum {
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NILFS_SC_DIRTY, /* One or more dirty meta-data blocks exist */
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NILFS_SC_UNCLOSED, /* Logical segment is not closed */
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NILFS_SC_SUPER_ROOT, /* The latest segment has a super root */
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NILFS_SC_PRIOR_FLUSH, /* Requesting immediate flush without making a
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checkpoint */
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NILFS_SC_HAVE_DELTA, /* Next checkpoint will have update of files
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other than DAT, cpfile, sufile, or files
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moved by GC */
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};
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/* sc_state */
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#define NILFS_SEGCTOR_QUIT 0x0001 /* segctord is being destroyed */
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#define NILFS_SEGCTOR_COMMIT 0x0004 /* committed transaction exists */
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/*
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* Constant parameters
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*/
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#define NILFS_SC_CLEANUP_RETRY 3 /* Retry count of construction when
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destroying segctord */
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/*
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* Default values of timeout, in seconds.
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*/
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#define NILFS_SC_DEFAULT_TIMEOUT 5 /* Timeout value of dirty blocks.
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It triggers construction of a
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logical segment with a super root */
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#define NILFS_SC_DEFAULT_SR_FREQ 30 /* Maximum frequency of super root
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creation */
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/*
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* The default threshold amount of data, in block counts.
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*/
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#define NILFS_SC_DEFAULT_WATERMARK 3600
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/* super.c */
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extern struct kmem_cache *nilfs_transaction_cachep;
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/* segment.c */
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extern void nilfs_relax_pressure_in_lock(struct super_block *);
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extern int nilfs_construct_segment(struct super_block *);
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extern int nilfs_construct_dsync_segment(struct super_block *, struct inode *,
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loff_t, loff_t);
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extern void nilfs_flush_segment(struct super_block *, ino_t);
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extern int nilfs_clean_segments(struct super_block *, struct nilfs_argv *,
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void **);
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int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root);
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void nilfs_detach_log_writer(struct super_block *sb);
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/* recovery.c */
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extern int nilfs_read_super_root_block(struct the_nilfs *, sector_t,
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struct buffer_head **, int);
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extern int nilfs_search_super_root(struct the_nilfs *,
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struct nilfs_recovery_info *);
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int nilfs_salvage_orphan_logs(struct the_nilfs *nilfs, struct super_block *sb,
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struct nilfs_recovery_info *ri);
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extern void nilfs_dispose_segment_list(struct list_head *);
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#endif /* _NILFS_SEGMENT_H */
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