ext3: Wait for proper transaction commit on fsync

We cannot rely on buffer dirty bits during fsync because pdflush can come
before fsync is called and clear dirty bits without forcing a transaction
commit. What we do is that we track which transaction has last changed
the inode and which transaction last changed allocation and force it to
disk on fsync.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

fs/ext3/super.c

@@ -466,6 +466,8 @@ static struct inode *ext3_alloc_inode(struct super_block *sb)
 		return NULL;
 	ei->i_block_alloc_info = NULL;
 	ei->vfs_inode.i_version = 1;
+	atomic_set(&ei->i_datasync_tid, 0);
+	atomic_set(&ei->i_sync_tid, 0);
 	return &ei->vfs_inode;
 }