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Message-ID: <20327acc-e203-9a16-0ff4-f4e49e44c899@molgen.mpg.de>
Date: Mon, 31 Jul 2023 07:49:51 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: song@...nel.org, yukuai3@...wei.com, linux-raid@...r.kernel.org,
linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
yangerkun@...wei.com
Subject: Re: [PATCH -next] md/raid10: fix a 'conf->barrier' leakage in
raid10_takeover()
Dear Yu,
Thank you for your patch. Some minor style comments for the commit
message, you can also ignore.
Am 31.07.23 um 04:28 schrieb Yu Kuai:
> From: Yu Kuai <yukuai3@...wei.com>
>
> After commit 4d27e927344a ("md: don't quiesce in mddev_suspend()"),
> 'conf->barrier' will be leaked in the case that raid10 takeover raid0:
>
> level_store
> pers->takeover -> raid10_takeover
> raid10_takeover_raid0
> WRITE_ONCE(conf->barrier, 1)
>
> mddev_suspend
> // still raid0
> mddev->pers = pers
> // switch to raid10
> mddev_resume
> // resume without suspend
>
> After the above commit, mddev_resume() will not decrease 'conf->barrier'
> that is set in raid10_takeover_raid0().
>
> Fix this problem by remove the setting of 'conf->barrier' from
removing
or
… by not setting `conf->barrier` in …
> raid10_takeover_raid0().
>
> By the way, this problem is found while I'm trying to make
> mddev_suspend/resume() to be independent from raid personalities. rai10
rai*d*
> is the only personality to use reference count in the quiesce() callback
> and this problem is only related to raid10.
>
> Fixes: 4d27e927344a ("md: don't quiesce in mddev_suspend()")
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
> drivers/md/raid10.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 16aa9d735880..7704a4c7f469 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -4417,7 +4417,6 @@ static void *raid10_takeover_raid0(struct mddev *mddev, sector_t size, int devs)
> rdev->new_raid_disk = rdev->raid_disk * 2;
> rdev->sectors = size;
> }
> - WRITE_ONCE(conf->barrier, 1);
> }
>
> return conf;
Reviewed-by: Paul Menzel <pmenzel@...gen.mpg.de>
Kind regards,
Paul
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