btrfs: return ENODATA in case RST lookup fails

btrfs: return ENODATA in case RST lookup fails

In case a lookup in the RAID stripe-tree fails, return ENODATA instead of
ENOENT to better distinguish stripe-tree lookups from other code paths
where we return ENOENT.

Suggested-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>