From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Dorminy Subject: Re: [PATCH] dm-raid: stack limits instead of overwriting them. Date: Thu, 24 Sep 2020 12:45:43 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mikulas Patocka Cc: Mike Snitzer , device-mapper development , Zdenek Kabelac List-Id: dm-devel.ids I don't understand how this works... Can chunk_size_bytes be 0? If not, how is discard_granularity being set to 0? I think also limits is local to the ti in question here, initialized by blk_set_stacking_limits() via dm-table.c, and therefore has only default values and not anything to do with the underlying queue. So setting discard_granularity=max(discard_granularity, chunk_size_bytes) doesn't seem like it should be working, unless I'm not understanding what it's there for... And shouldn't melding in the target's desired io_hints into the existing queue limits be happening in blk_stack_limits() instead? (Also, it does lcm_not_zero() for stacking granularity, instead of max()...) On Thu, Sep 24, 2020 at 12:29 PM Mikulas Patocka wrote: > > This patch fixes a warning WARN_ON_ONCE(!q->limits.discard_granularity). > The reason is that the function raid_io_hints overwrote > limits->discard_granularity with zero. We need to properly stack the > limits instead of overwriting them. > > Signed-off-by: Mikulas Patocka > Cc: stable@vger.kernel.org > > --- > drivers/md/dm-raid.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > Index: linux-2.6/drivers/md/dm-raid.c > =================================================================== > --- linux-2.6.orig/drivers/md/dm-raid.c 2020-09-24 18:16:45.000000000 +0200 > +++ linux-2.6/drivers/md/dm-raid.c 2020-09-24 18:16:45.000000000 +0200 > @@ -3734,8 +3734,8 @@ static void raid_io_hints(struct dm_targ > * RAID0/4/5/6 don't and process large discard bios properly. > */ > if (rs_is_raid1(rs) || rs_is_raid10(rs)) { > - limits->discard_granularity = chunk_size_bytes; > - limits->max_discard_sectors = rs->md.chunk_sectors; > + limits->discard_granularity = max(limits->discard_granularity, chunk_size_bytes); > + limits->max_discard_sectors = min_not_zero(limits->max_discard_sectors, (unsigned)rs->md.chunk_sectors); > } > } > > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel >