[PATCH v2] btrfs: Simplify setup_nodes_for_search

[PATCH v2] btrfs: Simplify setup_nodes_for_search

[Nikolay Borisov]

The function is needlessly convoluted. Fix that by:

* Removing redundant sret variable definition in both if arms.

* Replace the again/done labels with direct return statements, the
function is short enough and doesn't do anything special upon exit.

* Remove BUG_ON on split_node returning a positive number - it can't
  happen as split_node returns either 0 or a negative error code.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---

V2:
- Initialize ret to 0 by default in case we don't hit any of the branch conditions
and simply exit.

 fs/btrfs/ctree.c | 30 ++++++++----------------------
 1 file changed, 8 insertions(+), 22 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 892b467347a3..5de33cd85cac 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2390,56 +2390,42 @@ setup_nodes_for_search(struct btrfs_trans_handle *trans,
 		       int *write_lock_level)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
-	int ret;
+	int ret = 0;

 	if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
 	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
-		int sret;

 		if (*write_lock_level < level + 1) {
 			*write_lock_level = level + 1;
 			btrfs_release_path(p);
-			goto again;
+			return -EAGAIN;
 		}

 		reada_for_balance(p, level);
-		sret = split_node(trans, root, p, level);
+		ret = split_node(trans, root, p, level);

-		BUG_ON(sret > 0);
-		if (sret) {
-			ret = sret;
-			goto done;
-		}
 		b = p->nodes[level];
 	} else if (ins_len < 0 && btrfs_header_nritems(b) <
 		   BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
-		int sret;

 		if (*write_lock_level < level + 1) {
 			*write_lock_level = level + 1;
 			btrfs_release_path(p);
-			goto again;
+			return -EAGAIN;
 		}

 		reada_for_balance(p, level);
-		sret = balance_level(trans, root, p, level);
+		ret = balance_level(trans, root, p, level);
+		if (ret)
+			return ret;

-		if (sret) {
-			ret = sret;
-			goto done;
-		}
 		b = p->nodes[level];
 		if (!b) {
 			btrfs_release_path(p);
-			goto again;
+			return -EAGAIN;
 		}
 		BUG_ON(btrfs_header_nritems(b) == 1);
 	}
-	return 0;
-
-again:
-	ret = -EAGAIN;
-done:
 	return ret;
 }

--
2.25.1

Re: [PATCH v2] btrfs: Simplify setup_nodes_for_search

[Josef Bacik]

On 11/13/20 2:29 AM, Nikolay Borisov wrote:
> The function is needlessly convoluted. Fix that by:
> 
> * Removing redundant sret variable definition in both if arms.
> 
> * Replace the again/done labels with direct return statements, the
> function is short enough and doesn't do anything special upon exit.
> 
> * Remove BUG_ON on split_node returning a positive number - it can't
>    happen as split_node returns either 0 or a negative error code.
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
> 
> V2:
> - Initialize ret to 0 by default in case we don't hit any of the branch conditions
> and simply exit.
> 
>   fs/btrfs/ctree.c | 30 ++++++++----------------------
>   1 file changed, 8 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index 892b467347a3..5de33cd85cac 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -2390,56 +2390,42 @@ setup_nodes_for_search(struct btrfs_trans_handle *trans,
>   		       int *write_lock_level)
>   {
>   	struct btrfs_fs_info *fs_info = root->fs_info;
> -	int ret;
> +	int ret = 0;
> 
>   	if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
>   	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
> -		int sret;
> 
>   		if (*write_lock_level < level + 1) {
>   			*write_lock_level = level + 1;
>   			btrfs_release_path(p);
> -			goto again;
> +			return -EAGAIN;
>   		}
> 
>   		reada_for_balance(p, level);
> -		sret = split_node(trans, root, p, level);
> +		ret = split_node(trans, root, p, level);
> 
> -		BUG_ON(sret > 0);
> -		if (sret) {
> -			ret = sret;
> -			goto done;
> -		}
>   		b = p->nodes[level];

While you're cleaning up you could delete this line as well.

>   	} else if (ins_len < 0 && btrfs_header_nritems(b) <
>   		   BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
> -		int sret;
> 
>   		if (*write_lock_level < level + 1) {
>   			*write_lock_level = level + 1;
>   			btrfs_release_path(p);
> -			goto again;
> +			return -EAGAIN;
>   		}
> 
>   		reada_for_balance(p, level);
> -		sret = balance_level(trans, root, p, level);
> +		ret = balance_level(trans, root, p, level);
> +		if (ret)
> +			return ret;
> 
> -		if (sret) {
> -			ret = sret;
> -			goto done;
> -		}
>   		b = p->nodes[level];
>   		if (!b) {
>   			btrfs_release_path(p);
> -			goto again;
> +			return -EAGAIN;
>   		}
>   		BUG_ON(btrfs_header_nritems(b) == 1);

And change this to ASSERT().  Thanks,

Josef

Re: [PATCH v2] btrfs: Simplify setup_nodes_for_search

[David Sterba]

On Fri, Nov 13, 2020 at 09:29:40AM +0200, Nikolay Borisov wrote:
> The function is needlessly convoluted. Fix that by:
> 
> * Removing redundant sret variable definition in both if arms.
> 
> * Replace the again/done labels with direct return statements, the
> function is short enough and doesn't do anything special upon exit.
> 
> * Remove BUG_ON on split_node returning a positive number - it can't
>   happen as split_node returns either 0 or a negative error code.
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>

Added to misc-next, thanks.