Re: [PATCH] btrfs: volumes: Increase bioc pointer check

[Nikolay Borisov]

On 25.10.22 г. 11:28 ч., Li zeming wrote:
> If kzalloc fails to allocate the bioc pointer, NULL is returned
> directly.
>
> Signed-off-by: Li zeming <zeming@xxxxxxxxxxxx>

This patch clearly shows you haven't really understood the code. As is 
evident there is __GFP_NOFAIL flag so as per the guarantees for this 
flag we either loop infinitely trying to allocate a bioc or simply 
allocated it. So this check can never be triggered.

NAK
> ---
>   fs/btrfs/volumes.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 064ab2a79c80..f9cb815fe23d 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -5892,6 +5892,8 @@ static struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_
>   		 */
>   		sizeof(u64) * (total_stripes),
>   		GFP_NOFS|__GFP_NOFAIL);
> +	if (!bioc)
> +		return NULL;
>   
>   	atomic_set(&bioc->error, 0);
>   	refcount_set(&bioc->refs, 1);