[PATCH AUTOSEL 4.19 2/2] btrfs: fix warning on PTR_ERR() against NULL device at btrfs_control_ioctl()

[Sasha Levin <sashal@kernel.org>]

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit 2342d6595b608eec94187a17dc112dd4c2a812fa ]

Smatch complains about calling PTR_ERR() against a NULL pointer:

  fs/btrfs/super.c:2272 btrfs_control_ioctl() warn: passing zero to 'PTR_ERR'

Fix this by calling PTR_ERR() against the device pointer only if it
contains an error.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/super.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index a595439518519..086d6d397f0be 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2283,7 +2283,10 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 					       &btrfs_root_fs_type);
 		if (IS_ERR(device)) {
 			mutex_unlock(&uuid_mutex);
-			ret = PTR_ERR(device);
+			if (IS_ERR(device))
+				ret = PTR_ERR(device);
+			else
+				ret = 0;
 			break;
 		}
 		ret = !(device->fs_devices->num_devices ==
-- 
2.43.0