Re: [PATCH v11 05/40] btrfs: release path before calling into btrfs_load_block_group_zone_info

[Josef Bacik <josef@toxicpanda.com>]

On 12/21/20 10:48 PM, Naohiro Aota wrote:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> 
> Since we have no write pointer in conventional zones, we cannot determine
> allocation offset from it. Instead, we set the allocation offset after the
> highest addressed extent. This is done by reading the extent tree in
> btrfs_load_block_group_zone_info(). However, this function is called from
> btrfs_read_block_groups(), so the read lock for the tree node can
> recursively taken.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>   fs/btrfs/block-group.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index b8bbdd95743e..69e1b24bbbad 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -1839,6 +1839,7 @@ static int read_one_block_group(struct btrfs_fs_info *info,
>   		return -ENOMEM;
>   
>   	read_block_group_item(cache, path, key);
> +	btrfs_release_path(path);
>   
>   	set_free_space_tree_thresholds(cache);
>   
> @@ -2009,7 +2010,6 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
>   			goto error;
>   		key.objectid += key.offset;
>   		key.offset = 0;
> -		btrfs_release_path(path);
>   	}
>   	btrfs_release_path(path);
>   
> 

Instead why don't we just read in the bgi into the stack, and pass the pointer 
into read_one_block_group(), drop the path before calling read_one_block_group? 
  We don't use the path in read_one_block_group, there's no reason to pass it 
in.  It'll fix your problem and make it a little cleaner.  Thanks,

Josef