Re: [PATCH] btrfs: reorganize error handling in btrfs_tree_mod_log_insert_key

[Qu Wenruo <wqu@suse.com>]

在 2025/9/29 16:26, Sun YangKai 写道:
> Restructure the error handling flow in btrfs_tree_mod_log_insert_key
> to address memory allocation failures more cleanly.
> 
> No functional changes are made - this is purely a code readability
> improvement.
> 
> Signed-off-by: Sun YangKai <sunk67188@gmail.com>
> ---
>   fs/btrfs/tree-mod-log.c | 17 +++++++----------
>   1 file changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/btrfs/tree-mod-log.c b/fs/btrfs/tree-mod-log.c
> index 9e8cb3b7c064..4fd7859ad7dc 100644
> --- a/fs/btrfs/tree-mod-log.c
> +++ b/fs/btrfs/tree-mod-log.c
> @@ -267,9 +267,8 @@ int btrfs_tree_mod_log_insert_key(const struct extent_buffer *eb, int slot,
>   	if (!tree_mod_need_log(eb->fs_info, eb))
>   		return 0;
>   
> +	/* Allocation error is handled later. */
>   	tm = alloc_tree_mod_elem(eb, slot, op);
> -	if (!tm)
> -		ret = -ENOMEM;
>   
>   	if (tree_mod_dont_log(eb->fs_info, eb)) {
>   		kfree(tm);
> @@ -278,16 +277,14 @@ int btrfs_tree_mod_log_insert_key(const struct extent_buffer *eb, int slot,
>   		 * need to log.
>   		 */
>   		return 0;
> -	} else if (ret != 0) {
> -		/*
> -		 * We previously failed to allocate memory and we need to log,
> -		 * so we have to fail.
> -		 */
> -		goto out_unlock;
>   	}
>   
> -	ret = tree_mod_log_insert(eb->fs_info, tm);
> -out_unlock:
> +	/* Deal with allocation error. */
> +	if (tm)
> +		ret = tree_mod_log_insert(eb->fs_info, tm);

Sorry, I don't think this is really that better.

In fact I'm wondering why we don't delay the allocation after 
tree_mod_dont_log()?

That would be way more straightforward.

Thanks,
Qu
> +	else
> +		ret = -ENOMEM;
> +
>   	write_unlock(&eb->fs_info->tree_mod_log_lock);
>   	if (ret)
>   		kfree(tm);