[PATCH stable only] nvmet: set loop queue's segment boundary mask as PAGE_SIZE - 1

[PATCH stable only] nvmet: set loop queue's segment boundary mask as PAGE_SIZE - 1

[Ming Lei]

NVMe target only accepts single-page sg list, either file or block
device backed target code follows this assumption.

However, loop target is one exception, given the sg list is from
the host queue directly.

This patch sets loop queue's segment boundary mask as PAGE_SIZE - 1
for following NVMe target assumption.

Reported-by: Yi Zhang <yi.zhang@redhat.com>
Fixes: 3a85a5de29ea ("nvme-loop: add a NVMe loopback host driver")
Cc: Yi Zhang <yi.zhang@redhat.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/nvme/target/loop.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index b9f623ab01f3..7194f86b9dac 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -549,6 +549,9 @@ static int nvme_loop_create_io_queues(struct nvme_loop_ctrl *ctrl)
 	if (ret)
 		goto out_cleanup_connect_q;
 
+	/* target only accepts single-page sg list */
+	blk_queue_segment_boundary(ctrl->ctrl.connect_q, PAGE_SIZE - 1);
+
 	return 0;
 
 out_cleanup_connect_q:
-- 
2.9.5

Re: [PATCH stable only] nvmet: set loop queue's segment boundary mask as PAGE_SIZE - 1

[Sasha Levin]

On Wed, Mar 27, 2019 at 05:02:30PM +0800, Ming Lei wrote:
>NVMe target only accepts single-page sg list, either file or block
>device backed target code follows this assumption.
>
>However, loop target is one exception, given the sg list is from
>the host queue directly.
>
>This patch sets loop queue's segment boundary mask as PAGE_SIZE - 1
>for following NVMe target assumption.
>
>Reported-by: Yi Zhang <yi.zhang@redhat.com>
>Fixes: 3a85a5de29ea ("nvme-loop: add a NVMe loopback host driver")
>Cc: Yi Zhang <yi.zhang@redhat.com>
>Cc: Sagi Grimberg <sagi@grimberg.me>
>Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
>Cc: <stable@vger.kernel.org>
>Signed-off-by: Ming Lei <ming.lei@redhat.com>

Could you provide some background as to why this is -stable only in the
commit message?

--
Thanks,
Sasha

Re: [PATCH stable only] nvmet: set loop queue's segment boundary mask as PAGE_SIZE - 1

[Ming Lei]

On Wed, Mar 27, 2019 at 12:16:58PM -0400, Sasha Levin wrote:
> On Wed, Mar 27, 2019 at 05:02:30PM +0800, Ming Lei wrote:
> > NVMe target only accepts single-page sg list, either file or block
> > device backed target code follows this assumption.
> > 
> > However, loop target is one exception, given the sg list is from
> > the host queue directly.
> > 
> > This patch sets loop queue's segment boundary mask as PAGE_SIZE - 1
> > for following NVMe target assumption.
> > 
> > Reported-by: Yi Zhang <yi.zhang@redhat.com>
> > Fixes: 3a85a5de29ea ("nvme-loop: add a NVMe loopback host driver")
> > Cc: Yi Zhang <yi.zhang@redhat.com>
> > Cc: Sagi Grimberg <sagi@grimberg.me>
> > Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> 
> Could you provide some background as to why this is -stable only in the
> commit message?

Multi-page bvec has been merged to linus tree already, so the following
patch simply can fix the current issue without needing to limit the segment
size for nvme-loop:

http://lists.infradead.org/pipermail/linux-nvme/2019-March/023105.html

Thanks,
Ming

Re: [PATCH stable only] nvmet: set loop queue's segment boundary mask as PAGE_SIZE - 1

[Greg KH]

On Thu, Mar 28, 2019 at 08:55:06AM +0800, Ming Lei wrote:
> On Wed, Mar 27, 2019 at 12:16:58PM -0400, Sasha Levin wrote:
> > On Wed, Mar 27, 2019 at 05:02:30PM +0800, Ming Lei wrote:
> > > NVMe target only accepts single-page sg list, either file or block
> > > device backed target code follows this assumption.
> > > 
> > > However, loop target is one exception, given the sg list is from
> > > the host queue directly.
> > > 
> > > This patch sets loop queue's segment boundary mask as PAGE_SIZE - 1
> > > for following NVMe target assumption.
> > > 
> > > Reported-by: Yi Zhang <yi.zhang@redhat.com>
> > > Fixes: 3a85a5de29ea ("nvme-loop: add a NVMe loopback host driver")
> > > Cc: Yi Zhang <yi.zhang@redhat.com>
> > > Cc: Sagi Grimberg <sagi@grimberg.me>
> > > Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> > > Cc: <stable@vger.kernel.org>
> > > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > 
> > Could you provide some background as to why this is -stable only in the
> > commit message?
> 
> Multi-page bvec has been merged to linus tree already, so the following
> patch simply can fix the current issue without needing to limit the segment
> size for nvme-loop:
> 
> http://lists.infradead.org/pipermail/linux-nvme/2019-March/023105.html

Can you resend the patch with this needed information in it?  Also, I
don't understand what you are referring to with that url, why can't we
just use that patch?

thanks,

greg k-h

Re: [PATCH stable only] nvmet: set loop queue's segment boundary mask as PAGE_SIZE - 1

[Ming Lei]

On Mon, Apr 01, 2019 at 03:55:09PM +0200, Greg KH wrote:
> On Thu, Mar 28, 2019 at 08:55:06AM +0800, Ming Lei wrote:
> > On Wed, Mar 27, 2019 at 12:16:58PM -0400, Sasha Levin wrote:
> > > On Wed, Mar 27, 2019 at 05:02:30PM +0800, Ming Lei wrote:
> > > > NVMe target only accepts single-page sg list, either file or block
> > > > device backed target code follows this assumption.
> > > > 
> > > > However, loop target is one exception, given the sg list is from
> > > > the host queue directly.
> > > > 
> > > > This patch sets loop queue's segment boundary mask as PAGE_SIZE - 1
> > > > for following NVMe target assumption.
> > > > 
> > > > Reported-by: Yi Zhang <yi.zhang@redhat.com>
> > > > Fixes: 3a85a5de29ea ("nvme-loop: add a NVMe loopback host driver")
> > > > Cc: Yi Zhang <yi.zhang@redhat.com>
> > > > Cc: Sagi Grimberg <sagi@grimberg.me>
> > > > Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> > > > Cc: <stable@vger.kernel.org>
> > > > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > > 
> > > Could you provide some background as to why this is -stable only in the
> > > commit message?
> > 
> > Multi-page bvec has been merged to linus tree already, so the following
> > patch simply can fix the current issue without needing to limit the segment
> > size for nvme-loop:
> > 
> > http://lists.infradead.org/pipermail/linux-nvme/2019-March/023105.html
> 
> Can you resend the patch with this needed information in it?  Also, I
> don't understand what you are referring to with that url, why can't we
> just use that patch?

Sure, will resend the patch with the above info soon.

Thanks,
Ming