[PATCH 3/4] btrfs: bug_on for num_devices below 0

[Anand Jain <anand.jain@oracle.com>]

In preparation to add helper function to deduce the num_devices with
replace running, use bug_on instead of warn_on. In btrfs_rm_device()
the check for min devices happens in btrfs_check_raid_min_devices()
but its after its been decremented so a check here is better.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/volumes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c62b5e46792e..fe74fefc75f7 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1868,7 +1868,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	num_devices = fs_devices->num_devices;
 	btrfs_dev_replace_read_lock(&fs_info->dev_replace);
 	if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
-		WARN_ON(num_devices < 1);
+		BUG_ON(num_devices < 1);
 		num_devices--;
 	}
 	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
-- 
2.7.0