Btrfs: check return value of btrfs_cow_block()

The two helper functions commit_cowonly_roots() and
create_pending_snapshot() failed to check the return value from
btrfs_cow_block(), which could at least in theory fail with -ENOSPC from
btrfs_alloc_free_block(). This commit adds the missing checks.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 04b77e3ceb7a..cd220f283638 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -718,7 +718,8 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
         BUG_ON(ret);
 
         eb = btrfs_lock_root_node(fs_info->tree_root);
-        btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
+        ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
+        BUG_ON(ret);
         btrfs_tree_unlock(eb);
         free_extent_buffer(eb);
 
@@ -949,7 +950,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         btrfs_set_root_flags(new_root_item, root_flags);
 
         old = btrfs_lock_root_node(root);
-        btrfs_cow_block(trans, root, old, NULL, 0, &old);
+        ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
+        BUG_ON(ret);
         btrfs_set_lock_blocking(old);
 
         btrfs_copy_root(trans, root, old, &tmp, objectid);