linux-kernel - Re: [PATCH v2 1/3] fstests: use udevadm settle after pvremove

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Message-ID: <YRkKPbRX17kiAgz+@desktop>
Date:   Sun, 15 Aug 2021 20:36:13 +0800
From:   Eryu Guan <guan@...u.me>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     fstests@...r.kernel.org, hare@...e.de, dgilbert@...erlog.com,
        jeyu@...nel.org, lucas.demarchi@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] fstests: use udevadm settle after pvremove

On Wed, Aug 11, 2021 at 08:45:10AM -0700, Luis Chamberlain wrote:
> As with creation, we also need to use udevadm settle
> when removing a pv, otherwise we can trip on races with
> module removals for the block devices in use.
> 
> This reduces the amount of time in which a block device
> module refcnt for test modules such as scsi_debug spends
> outside of 0.
> 
> Races with the refcnt being greater than 0 means module
> removal can fail causing false positives. This helps
> ensure that the pv is really long gone. These issues
> are tracked for scsi_debug [0] and later found to be a
> generic issue regardless of filesystem with pvremove [1].
> 
> Using udevadm settle *helps*, it does not address all
> possible races with the refcnt as noted in the generic
> bug entry [1].
> 
> [0] https://bugzilla.kernel.org/show_bug.cgi?id=212337
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=214015
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>

I applied this patch for this week's update.

Thanks,
Eryu

> ---
>  tests/generic/081 | 5 ++++-
>  tests/generic/108 | 1 +
>  tests/generic/459 | 1 +
>  3 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/generic/081 b/tests/generic/081
> index f795b2c1..8e552074 100755
> --- a/tests/generic/081
> +++ b/tests/generic/081
> @@ -12,6 +12,7 @@ _begin_fstest auto quick
>  # Override the default cleanup function.
>  _cleanup()
>  {
> +	local pv_ret
>  	cd /
>  	rm -f $tmp.*
>  
> @@ -34,7 +35,9 @@ _cleanup()
>  		$UMOUNT_PROG $mnt >> $seqres.full 2>&1
>  		$LVM_PROG vgremove -f $vgname >>$seqres.full 2>&1
>  		$LVM_PROG pvremove -f $SCRATCH_DEV >>$seqres.full 2>&1
> -		test $? -eq 0 && break
> +		pv_ret=$?
> +		$UDEV_SETTLE_PROG
> +		test $pv_ret -eq 0 && break
>  		sleep 2
>  	done
>  }
> diff --git a/tests/generic/108 b/tests/generic/108
> index 7dd426c1..b7797e8f 100755
> --- a/tests/generic/108
> +++ b/tests/generic/108
> @@ -21,6 +21,7 @@ _cleanup()
>  	$UMOUNT_PROG $SCRATCH_MNT >>$seqres.full 2>&1
>  	$LVM_PROG vgremove -f $vgname >>$seqres.full 2>&1
>  	$LVM_PROG pvremove -f $SCRATCH_DEV $SCSI_DEBUG_DEV >>$seqres.full 2>&1
> +	$UDEV_SETTLE_PROG
>  	_put_scsi_debug_dev
>  	rm -f $tmp.*
>  }
> diff --git a/tests/generic/459 b/tests/generic/459
> index e5e5e9ab..5b44e245 100755
> --- a/tests/generic/459
> +++ b/tests/generic/459
> @@ -29,6 +29,7 @@ _cleanup()
>  	$UMOUNT_PROG $SCRATCH_MNT >>$seqres.full 2>&1
>  	$LVM_PROG vgremove -ff $vgname >>$seqres.full 2>&1
>  	$LVM_PROG pvremove -ff $SCRATCH_DEV >>$seqres.full 2>&1
> +	$UDEV_SETTLE_PROG
>  }
>  
>  # Import common functions.
> -- 
> 2.30.2