btrfs: do proper error handling in btrfs_update_reloc_root

stable inclusion
from stable-5.10.36
commit f32b84d7c977e1906a4781b93b3c93090b6cd675
bugzilla: 51867
CVE: NA

--------------------------------

[ Upstream commit 592fbcd5 ]

We call btrfs_update_root in btrfs_update_reloc_root, which can fail for
all sorts of reasons, including IO errors.  Instead of panicing the box
lets return the error, now that all callers properly handle those
errors.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/btrfs/relocation.c

@@ -897,7 +897,7 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
 	int ret;
 
 	if (!have_reloc_root(root))
-		goto out;
+		return 0;
 
 	reloc_root = root->reloc_root;
 	root_item = &reloc_root->root_item;
@@ -930,10 +930,8 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
 
 	ret = btrfs_update_root(trans, fs_info->tree_root,
 				&reloc_root->root_key, root_item);
-	BUG_ON(ret);
 	btrfs_put_root(reloc_root);
-out:
-	return 0;
+	return ret;
 }
 
 /*