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authorJan Kara <jack@suse.cz>2009-04-27 16:43:51 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2009-06-11 21:36:03 -0400
commit5cee5815d1564bbbd505fea86f4550f1efdb5cd0 (patch)
treeba99c38932dc534bf56f0d7dcfeeca153f50b007 /fs/super.c
parent429479f031322a0cc5c921ffb2321a51718dc875 (diff)
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vfs: Make sys_sync() use fsync_super() (version 4)
It is unnecessarily fragile to have two places (fsync_super() and do_sync()) doing data integrity sync of the filesystem. Alter __fsync_super() to accommodate needs of both callers and use it. So after this patch __fsync_super() is the only place where we gather all the calls needed to properly send all data on a filesystem to disk. Nice bonus is that we get a complete livelock avoidance and write_supers() is now only used for periodic writeback of superblocks. sync_blockdevs() introduced a couple of patches ago is gone now. [build fixes folded] Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c72
1 files changed, 23 insertions, 49 deletions
diff --git a/fs/super.c b/fs/super.c
index 8dbe1ead9ddd..c8ce5ed04249 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -284,23 +284,23 @@ EXPORT_SYMBOL(lock_super);
EXPORT_SYMBOL(unlock_super);
/*
- * 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. Requires a second blkdev
- * flush by the caller to complete the operation.
+ * 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)
+static int __fsync_super(struct super_block *sb, int wait)
{
- sync_inodes_sb(sb, 0);
vfs_dq_sync(sb);
- sync_inodes_sb(sb, 1);
+ 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, 1);
- return sync_blockdev(sb->s_bdev);
+ sb->s_op->sync_fs(sb, wait);
+ return __sync_blockdev(sb->s_bdev, wait);
}
/*
@@ -310,7 +310,12 @@ static int __fsync_super(struct super_block *sb)
*/
int fsync_super(struct super_block *sb)
{
- return __fsync_super(sb);
+ int ret;
+
+ ret = __fsync_super(sb, 0);
+ if (ret < 0)
+ return ret;
+ return __fsync_super(sb, 1);
}
EXPORT_SYMBOL_GPL(fsync_super);
@@ -469,20 +474,18 @@ restart:
}
/*
- * Call the ->sync_fs super_op against all filesystems which are r/w and
- * which implement it.
+ * 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_fs
+ * 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_fs
+ * 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.
- *
- * (Fabian) Avoid sync_fs with clean fs & wait mode 0
*/
void sync_filesystems(int wait)
{
@@ -492,25 +495,23 @@ void sync_filesystems(int wait)
mutex_lock(&mutex); /* Could be down_interruptible */
spin_lock(&sb_lock);
list_for_each_entry(sb, &super_blocks, s_list) {
- if (!sb->s_op->sync_fs)
- continue;
if (sb->s_flags & MS_RDONLY)
continue;
- sb->s_need_sync_fs = 1;
+ sb->s_need_sync = 1;
}
restart:
list_for_each_entry(sb, &super_blocks, s_list) {
- if (!sb->s_need_sync_fs)
+ if (!sb->s_need_sync)
continue;
- sb->s_need_sync_fs = 0;
+ 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)
- sb->s_op->sync_fs(sb, wait);
+ __fsync_super(sb, wait);
up_read(&sb->s_umount);
/* restart only when sb is no longer on the list */
spin_lock(&sb_lock);
@@ -521,33 +522,6 @@ restart:
mutex_unlock(&mutex);
}
-#ifdef CONFIG_BLOCK
-/*
- * Sync all block devices underlying some superblock
- */
-void sync_blockdevs(void)
-{
- struct super_block *sb;
-
- spin_lock(&sb_lock);
-restart:
- list_for_each_entry(sb, &super_blocks, s_list) {
- if (!sb->s_bdev)
- continue;
- sb->s_count++;
- spin_unlock(&sb_lock);
- down_read(&sb->s_umount);
- if (sb->s_root)
- sync_blockdev(sb->s_bdev);
- up_read(&sb->s_umount);
- spin_lock(&sb_lock);
- if (__put_super_and_need_restart(sb))
- goto restart;
- }
- spin_unlock(&sb_lock);
-}
-#endif
-
/**
* get_super - get the superblock of a device
* @bdev: device to get the superblock for