linux-kernel - Re: [dm-devel] [PATCH v7 12/13] dm: call dm_zone_endio after the target endio callback for zoned devices

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Date:   Fri, 17 Jun 2022 08:33:53 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Pankaj Raghav <p.raghav@...sung.com>, hch@....de,
        snitzer@...hat.com, axboe@...nel.dk
Cc:     bvanassche@....org, pankydev8@...il.com, gost.dev@...sung.com,
        jiangbo.365@...edance.com, linux-nvme@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        dm-devel@...hat.com, jonathan.derrick@...ux.dev,
        Johannes.Thumshirn@....com, dsterba@...e.com, jaegeuk@...nel.org
Subject: Re: [dm-devel] [PATCH v7 12/13] dm: call dm_zone_endio after the
 target endio callback for zoned devices

On 6/16/22 21:24, Pankaj Raghav wrote:
> On 2022-06-15 13:01, Damien Le Moal wrote:
>> On 6/15/22 19:19, Pankaj Raghav wrote:
>>> dm_zone_endio() updates the bi_sector of orig bio for zoned devices that
>>> uses either native append or append emulation and it is called before the
>>> endio of the target. But target endio can still update the clone bio
>>> after dm_zone_endio is called, thereby, the orig bio does not contain
>>> the updated information anymore. Call dm_zone_endio for zoned devices
>>> after calling the target's endio function
>>>
>>> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
>>> ---
>>> @Damien and @Hannes: I couldn't come up with a testcase that uses endio callback and
>>> zone append or append emulation for zoned devices to test for
>>> regression in this change. It would be great if you can suggest
>>> something. This change is required for the npo2 target as we update the
>>> clone bio sector in the endio callback function and the orig bio should
>>> be updated only after the endio callback for zone appends.
>>
>> Running zonefs tests on top of dm-crypt will exercise DM zone append
>> emulation.
>>
> Thanks. However, I am facing issues creating a dm-crypt target with a
> zoned device. Steps:
> - cryptsetup luksFormat <zns-device>

luks format is not supported because cryptsetup does not write the
metadata sequentially. I am working on fixing that. Use the plain format.

> 
> is throwing a bunch of IO errors with the following error message:
> Device wipe error, offset 32768.
> Cannot wipe header on device <zns-device>.
> 
> I can observe the same behavior in both v5.18 and next-20220615 with
> cryptsetup 2.4.3.The same step is working correctly on a normal NVMe device.
> Am I doing something wrong?
> ZNS info: zsze 128M and zcap 128M with 50 zones
>>>
>>>  drivers/md/dm.c | 8 ++++----
>>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
>>> index 3f17fe1de..3a74e1038 100644
>>> --- a/drivers/md/dm.c
>>> +++ b/drivers/md/dm.c
>>> @@ -1025,10 +1025,6 @@ static void clone_endio(struct bio *bio)
>>>  			disable_write_zeroes(md);
>>>  	}
>>>  
>>> -	if (static_branch_unlikely(&zoned_enabled) &&
>>> -	    unlikely(blk_queue_is_zoned(bdev_get_queue(bio->bi_bdev))))
>>> -		dm_zone_endio(io, bio);
>>> -
>>>  	if (endio) {
>>>  		int r = endio(ti, bio, &error);
>>>  		switch (r) {
>>> @@ -1057,6 +1053,10 @@ static void clone_endio(struct bio *bio)
>>>  		}
>>>  	}
>>>  
>>> +	if (static_branch_unlikely(&zoned_enabled) &&
>>> +	    unlikely(blk_queue_is_zoned(bdev_get_queue(bio->bi_bdev))))
>>
>> blk_queue_is_zoned(bdev_get_queue(bio->bi_bdev))) ->
>> bdev_is_zoned(bio->bi_bdev)
>>
> Ok. Even though I just moved the statements, I think this is trivial
> enough to take it along.
>>> +		dm_zone_endio(io, bio);
>>> +
>>>  	if (static_branch_unlikely(&swap_bios_enabled) &&
>>>  	    unlikely(swap_bios_limit(ti, bio)))
>>>  		up(&md->swap_bios_semaphore);
>>
>>


-- 
Damien Le Moal
Western Digital Research