linux-ext4 - Re: [PATCH] ext4: check if group has free space

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Message-ID: <20190315043120.GI11334@mit.edu>
Date:   Fri, 15 Mar 2019 00:31:20 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Artem Blagodarenko <artem.blagodarenko@...il.com>
Cc:     linux-ext4@...r.kernel.org, adilger.kernel@...ger.ca,
        alexey.lyashkov@...il.com
Subject: Re: [PATCH] ext4: check if group has free space

On Thu, Mar 07, 2019 at 02:49:14PM +0300, Artem Blagodarenko wrote:
> Regular allocator make four groups processing loops to
> find good group to allocate blocks. On 4th loop it accept any
> group, even if there is no free space at all.
> 
> This patch adds group free space check to skip full groups.
> 
> Sigend-off-by: Artem Blagodarenko <c17828@...y.com>

This patch doesn't change anything.  Note the check that we have at
the very beginning of ext4_mb_good_group():

	free = grp->bb_free;
	if (free == 0)
		return 0;

This is before we even go into the case statement, so your change:

>  	case 3:
> -		return 1;
> +		/* Skip group without any free space */
> +		return free ? 1 : 0;

is a no-op; we will always be returning 1, since if free == 0, we would
have bailed out at the top of the function.

Cheers,

					- Ted