[PATCH] btrfs: fix err_cast.cocci warnings

[kbuild test robot]

From: Fengguang Wu <fengguang...@intel.com>

fs/btrfs/volumes.c:742:10-17: WARNING: ERR_CAST can be used with fs_devices


 Use ERR_CAST inlined function instead of ERR_PTR(PTR_ERR(...))

Generated by: scripts/coccinelle/api/err_cast.cocci

Fixes: bf155c98d312 ("btrfs: get device pointer from device_list_add()")
CC: Anand Jain <anand.j...@oracle.com>
Signed-off-by: Fengguang Wu <fengguang...@intel.com>
---

 volumes.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -739,7 +739,7 @@ static noinline struct btrfs_device *dev
        if (!fs_devices) {
                fs_devices = alloc_fs_devices(disk_super->fsid);
                if (IS_ERR(fs_devices))
-                       return ERR_PTR(PTR_ERR(fs_devices));
+                       return ERR_CAST(fs_devices);
 
                list_add(&fs_devices->list, &fs_uuids);