[dm-devel] [PATCH] dm mpath: enable WRITE SAME support
Mike Snitzer
snitzer at redhat.com
Wed May 1 13:29:22 UTC 2013
On Wed, May 01 2013 at 2:58am -0400,
Bharata B Rao <bharata.rao at gmail.com> wrote:
> On Tue, Apr 30, 2013 at 10:02 PM, Mike Snitzer <snitzer at redhat.com> wrote:
> > On Tue, Apr 30 2013 at 12:07am -0400,
> > Bharata B Rao <bharata.rao at gmail.com> wrote:
> >
> >>
> >> # lsblk
> >> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> >> sda 8:0 0 50G 0 disk
> >> └─mpathb (dm-12) 252:12 0 50G 0 mpath
> >> └─ws_vg-lvol0 (dm-11) 252:11 0 1G 0 lvm
> >> sde 8:64 0 50G 0 disk
> >> └─mpathb (dm-12) 252:12 0 50G 0 mpath
> >> └─ws_vg-lvol0 (dm-11) 252:11 0 1G 0 lvm
> >>
> >
> >
> > Anyway, this patch fixes things for me:
>
> Thanks, this fixes the issue for me too. However if LV/VG/PV are
> created on multipath device, then WRITE SAME still doesn't get
> advertised for the LV. I had to disable multipath and re-create
> LV/VG/PV on a normal device (/dev/sda as against /dev/mapper/mapathb)
> to get BLKZEROUT working on LV.
The multipath target did not opt-in to supporting WRITE SAME. Please
try this patch.
From: Mike Snitzer <snitzer at redhat.com>
Subject: [PATCH] dm mpath: enable WRITE SAME support
There is no reason to disallow WRITE SAME support. As far as multipath
is concerned it is just another write request.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm-mpath.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 51bb816..bdf26f5 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -907,6 +907,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
ti->num_flush_bios = 1;
ti->num_discard_bios = 1;
+ ti->num_write_same_bios = 1;
return 0;
--
1.7.1
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