linux-kernel - Re: [PATCH] ext4: Replace CR_FAST macro with inline function for readability

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Message-ID: <20230629140018.duaaxqnxe55yfvqq@quack3>
Date:   Thu, 29 Jun 2023 16:00:18 +0200
From:   Jan Kara <jack@...e.cz>
To:     Ojaswin Mujoo <ojaswin@...ux.ibm.com>
Cc:     linux-ext4@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
        Ritesh Harjani <riteshh@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>,
        Kemeng Shi <shikemeng@...weicloud.com>
Subject: Re: [PATCH] ext4: Replace CR_FAST macro with inline function for
 readability

On Thu 29-06-23 19:17:19, Ojaswin Mujoo wrote:
> Replace CR_FAST with ext4_mb_cr_expensive() inline function for better
> readability. This function returns true if the criteria is one of the
> expensive/slower ones where lots of disk IO/prefetching is acceptable.
> 
> No functional changes are intended in this patch.
> 
> Signed-off-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>

Thanks for this cleanup! Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

Just one suggestion for consideration below:

> @@ -2630,7 +2630,7 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
>  	free = grp->bb_free;
>  	if (free == 0)
>  		goto out;
> -	if (cr <= CR_FAST && free < ac->ac_g_ex.fe_len)
> +	if (cr <= CR_GOAL_LEN_SLOW && free < ac->ac_g_ex.fe_len)

Maybe this could be (!ext4_mb_cr_expensive(cr) || cr == CR_GOAL_LEN_SLOW)?
Or maybe more explanatory would be (cr < CR_ANY_FREE) because AFAIU that's
the only scan where we bother scanning groups that have no chance of
satisfying the full allocation? Anyway a short comment explaining this
might be useful. And in either case we can get rid of a bit confusing
CR_FAST define.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR