btrfs: sysfs label interface should check for read only FS

Not sure how this escaped many eyes so far

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index e6a5e7d82f42..b2e7bb4393f6 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -377,6 +377,9 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
         int ret;
         size_t p_len;
 
+        if (fs_info->sb->s_flags & MS_RDONLY)
+                return -EROFS;
+
         /*
          * p_len is the len until the first occurrence of either
          * '\n' or '\0'