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vfs: Move syncing code from super.c to sync.c (version 4)

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Move sync_filesystems(), __fsync_super(), fsync_super() from
super.c to sync.c where it fits better.

[build fixes folded]

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Jan Kara
2009-04-27 16:43:52 +02:00
committed by Al Viro
parent 5cee5815d1
commit c15c54f5f0
3 changed files with 86 additions and 87 deletions
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85
fs/sync.c
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@@ -18,6 +18,91 @@
#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
SYNC_FILE_RANGE_WAIT_AFTER)
/*
* Do the filesystem syncing work. For simple filesystems sync_inodes_sb(sb, 0)
* just dirties buffers with inodes so we have to submit IO for these buffers
* via __sync_blockdev(). This also speeds up the wait == 1 case since in that
* case write_inode() functions do sync_dirty_buffer() and thus effectively
* write one block at a time.
*/
static int __fsync_super(struct super_block *sb, int wait)
{
vfs_dq_sync(sb);
sync_inodes_sb(sb, wait);
lock_super(sb);
if (sb->s_dirt && sb->s_op->write_super)
sb->s_op->write_super(sb);
unlock_super(sb);
if (sb->s_op->sync_fs)
sb->s_op->sync_fs(sb, wait);
return __sync_blockdev(sb->s_bdev, wait);
}
/*
* Write out and wait upon all dirty data associated with this
* superblock. Filesystem data as well as the underlying block
* device. Takes the superblock lock.
*/
int fsync_super(struct super_block *sb)
{
int ret;
ret = __fsync_super(sb, 0);
if (ret < 0)
return ret;
return __fsync_super(sb, 1);
}
EXPORT_SYMBOL_GPL(fsync_super);
/*
* Sync all the data for all the filesystems (called by sys_sync() and
* emergency sync)
*
* This operation is careful to avoid the livelock which could easily happen
* if two or more filesystems are being continuously dirtied. s_need_sync
* is used only here. We set it against all filesystems and then clear it as
* we sync them. So redirtied filesystems are skipped.
*
* But if process A is currently running sync_filesystems and then process B
* calls sync_filesystems as well, process B will set all the s_need_sync
* flags again, which will cause process A to resync everything. Fix that with
* a local mutex.
*/
static void sync_filesystems(int wait)
{
struct super_block *sb;
static DEFINE_MUTEX(mutex);
mutex_lock(&mutex); /* Could be down_interruptible */
spin_lock(&sb_lock);
list_for_each_entry(sb, &super_blocks, s_list) {
if (sb->s_flags & MS_RDONLY)
continue;
sb->s_need_sync = 1;
}
restart:
list_for_each_entry(sb, &super_blocks, s_list) {
if (!sb->s_need_sync)
continue;
sb->s_need_sync = 0;
if (sb->s_flags & MS_RDONLY)
continue; /* hm. Was remounted r/o meanwhile */
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
if (sb->s_root)
__fsync_super(sb, wait);
up_read(&sb->s_umount);
/* restart only when sb is no longer on the list */
spin_lock(&sb_lock);
if (__put_super_and_need_restart(sb))
goto restart;
}
spin_unlock(&sb_lock);
mutex_unlock(&mutex);
}
SYSCALL_DEFINE0(sync)
{
sync_filesystems(0);