From c4be0c1dc4cdc37b175579be1460f15ac6495e9a Mon Sep 17 00:00:00 2001 From: Takashi Sato Date: Fri, 9 Jan 2009 16:40:58 -0800 Subject: filesystem freeze: add error handling of write_super_lockfs/unlockfs Currently, ext3 in mainline Linux doesn't have the freeze feature which suspends write requests. So, we cannot take a backup which keeps the filesystem's consistency with the storage device's features (snapshot and replication) while it is mounted. In many case, a commercial filesystem (e.g. VxFS) has the freeze feature and it would be used to get the consistent backup. If Linux's standard filesystem ext3 has the freeze feature, we can do it without a commercial filesystem. So I have implemented the ioctls of the freeze feature. I think we can take the consistent backup with the following steps. 1. Freeze the filesystem with the freeze ioctl. 2. Separate the replication volume or create the snapshot with the storage device's feature. 3. Unfreeze the filesystem with the unfreeze ioctl. 4. Take the backup from the separated replication volume or the snapshot. This patch: VFS: Changed the type of write_super_lockfs and unlockfs from "void" to "int" so that they can return an error. Rename write_super_lockfs and unlockfs of the super block operation freeze_fs and unfreeze_fs to avoid a confusion. ext3, ext4, xfs, gfs2, jfs: Changed the type of write_super_lockfs and unlockfs from "void" to "int" so that write_super_lockfs returns an error if needed, and unlockfs always returns 0. reiserfs: Changed the type of write_super_lockfs and unlockfs from "void" to "int" so that they always return 0 (success) to keep a current behavior. Signed-off-by: Takashi Sato Signed-off-by: Masayuki Hamaguchi Cc: Cc: Cc: Christoph Hellwig Cc: Dave Kleikamp Cc: Dave Chinner Cc: Alasdair G Kergon Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/reiserfs/super.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'fs/reiserfs') diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c index c55651f1407c..f3c820b75829 100644 --- a/fs/reiserfs/super.c +++ b/fs/reiserfs/super.c @@ -83,7 +83,7 @@ static void reiserfs_write_super(struct super_block *s) reiserfs_sync_fs(s, 1); } -static void reiserfs_write_super_lockfs(struct super_block *s) +static int reiserfs_freeze(struct super_block *s) { struct reiserfs_transaction_handle th; reiserfs_write_lock(s); @@ -101,11 +101,13 @@ static void reiserfs_write_super_lockfs(struct super_block *s) } s->s_dirt = 0; reiserfs_write_unlock(s); + return 0; } -static void reiserfs_unlockfs(struct super_block *s) +static int reiserfs_unfreeze(struct super_block *s) { reiserfs_allow_writes(s); + return 0; } extern const struct in_core_key MAX_IN_CORE_KEY; @@ -613,8 +615,8 @@ static const struct super_operations reiserfs_sops = { .put_super = reiserfs_put_super, .write_super = reiserfs_write_super, .sync_fs = reiserfs_sync_fs, - .write_super_lockfs = reiserfs_write_super_lockfs, - .unlockfs = reiserfs_unlockfs, + .freeze_fs = reiserfs_freeze, + .unfreeze_fs = reiserfs_unfreeze, .statfs = reiserfs_statfs, .remount_fs = reiserfs_remount, .show_options = generic_show_options, -- cgit v1.2.3-58-ga151