[PATCH] device-mapper: dm-raid1: Limit bios to size of mirror region

[PATCH] device-mapper: dm-raid1: Limit bios to size of mirror region

[Alasdair G Kergon]

Set the target's split_io field when building a dm-mirror device so
incoming bios won't span the mirror's internal regions.  Without
this, regions can be accessed while not holding correct locks and data
corruption is possible.

Reported-By: "Zhao Qian" <zhaoqian@aaastor.com>
From: Kevin Corry <kevcorry@us.ibm.com>
Signed-Off-By: Alasdair G Kergon <agk@redhat.com>

--- diff/drivers/md/dm-raid1.c	2005-06-17 20:48:29.000000000 +0100
+++ source/drivers/md/dm-raid1.c	2005-06-29 21:12:13.000000000 +0100
@@ -1060,6 +1060,7 @@
 	}
 
 	ti->private = ms;
+ 	ti->split_io = ms->rh->region_size;
 
 	r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
 	if (r) {

Re: [PATCH] device-mapper: dm-raid1: Limit bios to size of mirror region

[Andrew Morton]

Alasdair G Kergon <agk@redhat.com> wrote:
>
> Set the target's split_io field when building a dm-mirror device so
> incoming bios won't span the mirror's internal regions.  Without
> this, regions can be accessed while not holding correct locks and data
> corruption is possible.
> 
> Reported-By: "Zhao Qian" <zhaoqian@aaastor.com>
> From: Kevin Corry <kevcorry@us.ibm.com>
> Signed-Off-By: Alasdair G Kergon <agk@redhat.com>
> 
> --- diff/drivers/md/dm-raid1.c	2005-06-17 20:48:29.000000000 +0100
> +++ source/drivers/md/dm-raid1.c	2005-06-29 21:12:13.000000000 +0100
> @@ -1060,6 +1060,7 @@
>  	}
>  
>  	ti->private = ms;
> + 	ti->split_io = ms->rh->region_size;
>  
>  	r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
>  	if (r) {

Ahem.

drivers/md/dm-raid1.c: In function `mirror_ctr':
drivers/md/dm-raid1.c:1072: invalid type argument of `->'

--- devel/drivers/md/dm-raid1.c~device-mapper-dm-raid1-limit-bios-to-size-of-mirror-region-fix	2005-07-01 00:25:26.000000000 -0700
+++ devel-akpm/drivers/md/dm-raid1.c	2005-07-01 00:25:26.000000000 -0700
@@ -1060,7 +1060,7 @@ static int mirror_ctr(struct dm_target *
 	}
 
 	ti->private = ms;
- 	ti->split_io = ms->rh->region_size;
+ 	ti->split_io = ms->rh.region_size;
 
 	r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
 	if (r) {

How well tested was this?

Re: [PATCH] device-mapper: dm-raid1: Limit bios to size of mirror region

[Kevin Corry]

On Fri July 1 2005 2:26 am, Andrew Morton wrote:
> Alasdair G Kergon <agk@redhat.com> wrote:
> > --- diff/drivers/md/dm-raid1.c 2005-06-17 20:48:29.000000000 +0100
> > +++ source/drivers/md/dm-raid1.c 2005-06-29 21:12:13.000000000 +0100
> > @@ -1060,6 +1060,7 @@
> >   }
> >
> >   ti->private = ms;
> > +  ti->split_io = ms->rh->region_size;
> >
> >   r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
> >   if (r) {
>
> Ahem.
>
> drivers/md/dm-raid1.c: In function `mirror_ctr':
> drivers/md/dm-raid1.c:1072: invalid type argument of `->'
>
> ---
> devel/drivers/md/dm-raid1.c~device-mapper-dm-raid1-limit-bios-to-size-of-mi
>rror-region-fix 2005-07-01 00:25:26.000000000 -0700 +++
> devel-akpm/drivers/md/dm-raid1.c 2005-07-01 00:25:26.000000000 -0700 @@
> -1060,7 +1060,7 @@ static int mirror_ctr(struct dm_target *
>   }
>
>   ti->private = ms;
> -  ti->split_io = ms->rh->region_size;
> +  ti->split_io = ms->rh.region_size;
>
>   r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
>   if (r) {
>
> How well tested was this?

Ehh...oops...sorry about that. :(

Zhao, you reported this issue originally. Have you been able to test this yet 
to see if it fixes the corruption problem you were describing? Or can you 
give us a test-case that I can run?

-- 
Kevin Corry
kevcorry@us.ibm.com
http://www.ibm.com/linux/
http://evms.sourceforge.net/