btrfs: stop checking for -EEXIST return value from btrfs_uuid_tree_add()

We never return -EEXIST from btrfs_uuid_tree_add(), if the item already
exists we extend it, so it's pointless to check for such return value.

Furthermore, in create_pending_snapshot(), the logic is completely broken.
The goal was to not error out and abort the transaction in case of -EEXIST
but we left 'ret' with the -EEXIST value, so we end up setting
pending->error to -EEXIST and return that error up the call chain up to
btrfs_commit_transaction(), which will abort the transaction.

Reviewed-by: Boris Burkov <[email protected]>
Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: fdmanana

fs/btrfs/ioctl.c

@@ -3928,7 +3928,7 @@ static long _btrfs_ioctl_set_received_subvol(struct file *file,
 		ret = btrfs_uuid_tree_add(trans, sa->uuid,
 					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
 					  btrfs_root_id(root));
-		if (unlikely(ret < 0 && ret != -EEXIST)) {
+		if (unlikely(ret < 0)) {
 			btrfs_abort_transaction(trans, ret);
 			btrfs_end_transaction(trans);
 			goto out;

fs/btrfs/transaction.c

@@ -1918,7 +1918,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 		 */
 		if (ret == -EOVERFLOW)
 			ret = 0;
-		if (unlikely(ret && ret != -EEXIST)) {
+		if (unlikely(ret)) {
 			btrfs_abort_transaction(trans, ret);
 			goto fail;
 		}