Re: [PATCH] btrfs: emit a warning about space cache v1 being deprecated

[David Sterba <dsterba@suse.cz>]

On Mon, Jul 29, 2024 at 12:51:10PM -0400, Josef Bacik wrote:
> We've been wanting to get rid of this for a while, add a message to
> indicate that this feature is going away and when so we can finally have
> a date when we're going to remove it.  The output looks like this
> 
> BTRFS warning (device nvme0n1): space cache v1 is being deprecated and will be removed in a future release
> BTRFS warning (device nvme0n1): please use -o space_cache=v2
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  fs/btrfs/super.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 0eda8c21d861..1f2e9900e410 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -682,8 +682,12 @@ bool btrfs_check_options(const struct btrfs_fs_info *info, unsigned long *mount_
>  		ret = false;
>  
>  	if (!test_bit(BTRFS_FS_STATE_REMOUNTING, &info->fs_state)) {
> -		if (btrfs_raw_test_opt(*mount_opt, SPACE_CACHE))
> +		if (btrfs_raw_test_opt(*mount_opt, SPACE_CACHE)) {
>  			btrfs_info(info, "disk space caching is enabled");
> +			btrfs_warn(info,
> +		"space cache v1 is being deprecated and will be removed in a future release");
> +			btrfs_warn(info, "please use -o space_cache=v2");

Please don't split the printk message, the recommendation should be on
the same line as printk can insert another line between them.

> +		}
>  		if (btrfs_raw_test_opt(*mount_opt, FREE_SPACE_TREE))
>  			btrfs_info(info, "using free-space-tree");
>  	}
> -- 
> 2.43.0
>