Re: [PATCH] Rescan the entire target on transport reset when LUN is 0
On Fri, Aug 28, 2020 at 12:21:35PM +, Matej Genci wrote:
> VirtIO 1.0 spec says
> The removed and rescan events ... when sent for LUN 0, they MAY
> apply to the entire target so the driver can ask the initiator
> to rescan the target to detect this.
>
> This change introduces the behaviour described above by scanning the
> entire scsi target when LUN is set to 0. This is both a functional and a
> performance fix. It aligns the driver with the spec and allows control
> planes to hotplug targets with large numbers of LUNs without having to
> request a RESCAN for each one of them.
>
> Signed-off-by: Matej Genci
> Suggested-by: Felipe Franciosi
Stefan, Paolo, could you review this pls?
> ---
> drivers/scsi/virtio_scsi.c | 7 ++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index bfec84aacd90..a4b9bc7b4b4a 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -284,7 +284,12 @@ static void virtscsi_handle_transport_reset(struct
> virtio_scsi *vscsi,
>
> switch (virtio32_to_cpu(vscsi->vdev, event->reason)) {
> case VIRTIO_SCSI_EVT_RESET_RESCAN:
> - scsi_add_device(shost, 0, target, lun);
> + if (lun == 0) {
> + scsi_scan_target(&shost->shost_gendev, 0, target,
> + SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
> + } else {
> + scsi_add_device(shost, 0, target, lun);
> + }
> break;
> case VIRTIO_SCSI_EVT_RESET_REMOVED:
> sdev = scsi_device_lookup(shost, 0, target, lun);
> --
> 2.20.1
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Re: [PATCH] Rescan the entire target on transport reset when LUN is 0
On 28/08/20 14:21, Matej Genci wrote:
> VirtIO 1.0 spec says
> The removed and rescan events ... when sent for LUN 0, they MAY
> apply to the entire target so the driver can ask the initiator
> to rescan the target to detect this.
>
> This change introduces the behaviour described above by scanning the
> entire scsi target when LUN is set to 0. This is both a functional and a
> performance fix. It aligns the driver with the spec and allows control
> planes to hotplug targets with large numbers of LUNs without having to
> request a RESCAN for each one of them.
>
> Signed-off-by: Matej Genci
> Suggested-by: Felipe Franciosi
> ---
> drivers/scsi/virtio_scsi.c | 7 ++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index bfec84aacd90..a4b9bc7b4b4a 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -284,7 +284,12 @@ static void virtscsi_handle_transport_reset(struct
> virtio_scsi *vscsi,
>
> switch (virtio32_to_cpu(vscsi->vdev, event->reason)) {
> case VIRTIO_SCSI_EVT_RESET_RESCAN:
> - scsi_add_device(shost, 0, target, lun);
> + if (lun == 0) {
> + scsi_scan_target(&shost->shost_gendev, 0, target,
> + SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
> + } else {
> + scsi_add_device(shost, 0, target, lun);
> + }
> break;
> case VIRTIO_SCSI_EVT_RESET_REMOVED:
> sdev = scsi_device_lookup(shost, 0, target, lun);
>
Acked-by: Paolo Bonzini
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Re: [PATCH] Rescan the entire target on transport reset when LUN is 0
> On Sep 8, 2020, at 3:22 PM, Paolo Bonzini wrote:
>
> On 28/08/20 14:21, Matej Genci wrote:
>> VirtIO 1.0 spec says
>>The removed and rescan events ... when sent for LUN 0, they MAY
>>apply to the entire target so the driver can ask the initiator
>>to rescan the target to detect this.
>>
>> This change introduces the behaviour described above by scanning the
>> entire scsi target when LUN is set to 0. This is both a functional and a
>> performance fix. It aligns the driver with the spec and allows control
>> planes to hotplug targets with large numbers of LUNs without having to
>> request a RESCAN for each one of them.
>>
>> Signed-off-by: Matej Genci
>> Suggested-by: Felipe Franciosi
>> ---
>> drivers/scsi/virtio_scsi.c | 7 ++-
>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
>> index bfec84aacd90..a4b9bc7b4b4a 100644
>> --- a/drivers/scsi/virtio_scsi.c
>> +++ b/drivers/scsi/virtio_scsi.c
>> @@ -284,7 +284,12 @@ static void virtscsi_handle_transport_reset(struct
>> virtio_scsi *vscsi,
>>
>> switch (virtio32_to_cpu(vscsi->vdev, event->reason)) {
>> case VIRTIO_SCSI_EVT_RESET_RESCAN:
>> -scsi_add_device(shost, 0, target, lun);
>> +if (lun == 0) {
>> +scsi_scan_target(&shost->shost_gendev, 0, target,
>> + SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
>> +} else {
>> +scsi_add_device(shost, 0, target, lun);
>> +}
>> break;
>> case VIRTIO_SCSI_EVT_RESET_REMOVED:
>> sdev = scsi_device_lookup(shost, 0, target, lun);
>>
>
>
> Acked-by: Paolo Bonzini
Cc: sta...@vger.kernel.org
Thanks, Paolo.
I'm Cc'ing stable as I believe this fixes a driver bug where it
doesn't follow the spec. Per commit message, today devices are
required to issue RESCAN events for each LUN behind a target when
hotplugging, or risking the driver not seeing the new LUNs.
Is this enough? Or should we resend after merge per below?
https://www.kernel.org/doc/Documentation/process/stable-kernel-rules.rst
F.
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Re: [PATCH] Rescan the entire target on transport reset when LUN is 0
On Tue, Sep 08, 2020 at 05:53:16PM +, Felipe Franciosi wrote:
>
>
> > On Sep 8, 2020, at 3:22 PM, Paolo Bonzini wrote:
> >
> > On 28/08/20 14:21, Matej Genci wrote:
> >> VirtIO 1.0 spec says
> >>The removed and rescan events ... when sent for LUN 0, they MAY
> >>apply to the entire target so the driver can ask the initiator
> >>to rescan the target to detect this.
> >>
> >> This change introduces the behaviour described above by scanning the
> >> entire scsi target when LUN is set to 0. This is both a functional and a
> >> performance fix. It aligns the driver with the spec and allows control
> >> planes to hotplug targets with large numbers of LUNs without having to
> >> request a RESCAN for each one of them.
> >>
> >> Signed-off-by: Matej Genci
> >> Suggested-by: Felipe Franciosi
> >> ---
> >> drivers/scsi/virtio_scsi.c | 7 ++-
> >> 1 file changed, 6 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> >> index bfec84aacd90..a4b9bc7b4b4a 100644
> >> --- a/drivers/scsi/virtio_scsi.c
> >> +++ b/drivers/scsi/virtio_scsi.c
> >> @@ -284,7 +284,12 @@ static void virtscsi_handle_transport_reset(struct
> >> virtio_scsi *vscsi,
> >>
> >>switch (virtio32_to_cpu(vscsi->vdev, event->reason)) {
> >>case VIRTIO_SCSI_EVT_RESET_RESCAN:
> >> - scsi_add_device(shost, 0, target, lun);
> >> + if (lun == 0) {
> >> + scsi_scan_target(&shost->shost_gendev, 0, target,
> >> + SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
> >> + } else {
> >> + scsi_add_device(shost, 0, target, lun);
> >> + }
> >>break;
> >>case VIRTIO_SCSI_EVT_RESET_REMOVED:
> >>sdev = scsi_device_lookup(shost, 0, target, lun);
> >>
> >
> >
> > Acked-by: Paolo Bonzini
>
> Cc: sta...@vger.kernel.org
>
> Thanks, Paolo.
>
> I'm Cc'ing stable as I believe this fixes a driver bug where it
> doesn't follow the spec. Per commit message, today devices are
> required to issue RESCAN events for each LUN behind a target when
> hotplugging, or risking the driver not seeing the new LUNs.
>
> Is this enough? Or should we resend after merge per below?
> https://www.kernel.org/doc/Documentation/process/stable-kernel-rules.rst
You need to let stable know the git commit id of the patch in Linus's
tree if the cc: stable is not on the final commit that gets merged.
thanks,
greg k-h
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Re: [PATCH] Rescan the entire target on transport reset when LUN is 0
Matej, > This change introduces the behaviour described above by scanning the > entire scsi target when LUN is set to 0. This is both a functional and a > performance fix. It aligns the driver with the spec and allows control > planes to hotplug targets with large numbers of LUNs without having to > request a RESCAN for each one of them. Applied to 5.10/scsi-staging, thanks! -- Martin K. Petersen Oracle Linux Engineering ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH] Rescan the entire target on transport reset when LUN is 0
On Fri, 28 Aug 2020 12:21:35 +, Matej Genci wrote: > VirtIO 1.0 spec says > The removed and rescan events ... when sent for LUN 0, they MAY > apply to the entire target so the driver can ask the initiator > to rescan the target to detect this. > > This change introduces the behaviour described above by scanning the > entire scsi target when LUN is set to 0. This is both a functional and a > performance fix. It aligns the driver with the spec and allows control > planes to hotplug targets with large numbers of LUNs without having to > request a RESCAN for each one of them. Applied to 5.10/scsi-queue, thanks! [1/1] scsi: virtio_scsi: Rescan the entire target on transport reset when LUN is 0 https://git.kernel.org/mkp/scsi/c/beef6fd02b90 -- Martin K. Petersen Oracle Linux Engineering ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
