Btrfs: do not overwrite scrub error with fault error in scrub ioctl

If scrub returned an error and then the copy_to_user() call did not
succeed, we would overwrite the error returned by scrub with -EFAULT.
Fix that by calling copy_to_user() only if btrfs_scrub_dev() returned
success.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9c8e1734429c7649721eeadd3dca941ff2ee490c..d34e54d80149d0b9866989b11f201a7d0f19ba2a 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4381,7 +4381,7 @@ static long btrfs_ioctl_scrub(struct file *file, void __user *arg)
                              &sa->progress, sa->flags & BTRFS_SCRUB_READONLY,
                              0);
 
-       if (copy_to_user(arg, sa, sizeof(*sa)))
+       if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa)))
                ret = -EFAULT;
 
        if (!(sa->flags & BTRFS_SCRUB_READONLY))