Btrfs: fix remount vs autodefrag

If we remount the fs to close the auto defragment or make the fs R/O,
we should stop the auto defragment.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 3dcedfe..ae8dcc4 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -339,6 +339,7 @@
  * File system states
  */
 #define BTRFS_FS_STATE_ERROR		0
+#define BTRFS_FS_STATE_REMOUNTING	1
 
 /* Super block flags */
 /* Errors detected */
@@ -1902,6 +1903,7 @@
 
 #define btrfs_clear_opt(o, opt)		((o) &= ~BTRFS_MOUNT_##opt)
 #define btrfs_set_opt(o, opt)		((o) |= BTRFS_MOUNT_##opt)
+#define btrfs_raw_test_opt(o, opt)	((o) & BTRFS_MOUNT_##opt)
 #define btrfs_test_opt(root, opt)	((root)->fs_info->mount_opt & \
 					 BTRFS_MOUNT_##opt)
 /*