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[v6,0/4] virtio/block: handle zoned backing devices

Message ID 20190904210100.10501-1-dmitry.fomichev@wdc.com (mailing list archive)
Headers show
Series virtio/block: handle zoned backing devices | expand

Message

Dmitry Fomichev Sept. 4, 2019, 9 p.m. UTC
Currently, attaching zoned block devices (i.e., storage devices
compliant to ZAC/ZBC standards) using several virtio methods doesn't
work properly as zoned devices appear as regular block devices at the
guest. This may cause unexpected i/o errors and, potentially, some
data corruption.

To be more precise, attaching a zoned device via virtio-pci-blk,
virtio-scsi-pci/scsi-disk or virtio-scsi-pci/scsi-hd demonstrates the
above behavior. The virtio-scsi-pci/scsi-block method works with a
recent patch. The virtio-scsi-pci/scsi-generic method also appears to
handle zoned devices without problems.

This patch set adds code to check if the backing device that is being
opened is a zoned Host Managed device. If this is the case, the patch
prohibits attaching such device for all use cases lacking proper
zoned support.

Host Aware zoned block devices are designed to work as regular block
devices at a guest system that does not support ZBD. Therefore, this
patch set doesn't prohibit attachment of Host Aware devices.

Considering that there is still a couple of different working ways
to attach a ZBD, this patch set provides a reasonable short-term
solution for this problem.

ZBD support for virtio-scsi-pci/scsi-disk and virtio-scsi-pci/scsi-hd
does not seem as necessary. Users will be expected to attach zoned
block devices via virtio-scsi-pci/scsi-block instead.

This patch set contains some Linux-specific code. This code is
necessary to obtain Zoned Block Device model value from Linux sysfs.

History:

v1 -> v2:
- rework code to be permission-based
- always allow Host Aware devices to be attached
- add fix for Host Aware attachments aka RCAP output snoop

v2 -> v3:
- drop the patch for RCAP output snoop - merged separately

v3 -> v4:
- rebase to the current code

v4 -> v5:
- avoid checkpatch warning

v5 -> v6:
- address review comments from Stefan Hajnoczi

Dmitry Fomichev (4):
  block: Add zoned device model property
  raw: Recognize zoned backing devices
  block/ide/scsi: Set BLK_PERM_SUPPORT_HM_ZONED
  raw: Don't open ZBDs if backend can't handle them

 block.c                   | 15 +++++++
 block/file-posix.c        | 89 +++++++++++++++++++++++++++++++++------
 block/io.c                |  5 +++
 hw/block/block.c          |  8 +++-
 hw/block/fdc.c            |  5 ++-
 hw/block/nvme.c           |  2 +-
 hw/block/virtio-blk.c     |  2 +-
 hw/block/xen-block.c      |  2 +-
 hw/ide/qdev.c             |  2 +-
 hw/scsi/scsi-disk.c       | 13 +++---
 hw/scsi/scsi-generic.c    |  2 +-
 hw/usb/dev-storage.c      |  2 +-
 include/block/block.h     | 19 ++++++++-
 include/block/block_int.h |  3 ++
 include/hw/block/block.h  |  3 +-
 15 files changed, 141 insertions(+), 31 deletions(-)

Comments

Stefan Hajnoczi Sept. 5, 2019, 3:42 p.m. UTC | #1
On Wed, Sep 04, 2019 at 05:00:56PM -0400, Dmitry Fomichev wrote:
> Currently, attaching zoned block devices (i.e., storage devices
> compliant to ZAC/ZBC standards) using several virtio methods doesn't
> work properly as zoned devices appear as regular block devices at the
> guest. This may cause unexpected i/o errors and, potentially, some
> data corruption.
> 
> To be more precise, attaching a zoned device via virtio-pci-blk,
> virtio-scsi-pci/scsi-disk or virtio-scsi-pci/scsi-hd demonstrates the
> above behavior. The virtio-scsi-pci/scsi-block method works with a
> recent patch. The virtio-scsi-pci/scsi-generic method also appears to
> handle zoned devices without problems.
> 
> This patch set adds code to check if the backing device that is being
> opened is a zoned Host Managed device. If this is the case, the patch
> prohibits attaching such device for all use cases lacking proper
> zoned support.
> 
> Host Aware zoned block devices are designed to work as regular block
> devices at a guest system that does not support ZBD. Therefore, this
> patch set doesn't prohibit attachment of Host Aware devices.
> 
> Considering that there is still a couple of different working ways
> to attach a ZBD, this patch set provides a reasonable short-term
> solution for this problem.
> 
> ZBD support for virtio-scsi-pci/scsi-disk and virtio-scsi-pci/scsi-hd
> does not seem as necessary. Users will be expected to attach zoned
> block devices via virtio-scsi-pci/scsi-block instead.
> 
> This patch set contains some Linux-specific code. This code is
> necessary to obtain Zoned Block Device model value from Linux sysfs.
> 
> History:
> 
> v1 -> v2:
> - rework code to be permission-based
> - always allow Host Aware devices to be attached
> - add fix for Host Aware attachments aka RCAP output snoop
> 
> v2 -> v3:
> - drop the patch for RCAP output snoop - merged separately
> 
> v3 -> v4:
> - rebase to the current code
> 
> v4 -> v5:
> - avoid checkpatch warning
> 
> v5 -> v6:
> - address review comments from Stefan Hajnoczi
> 
> Dmitry Fomichev (4):
>   block: Add zoned device model property
>   raw: Recognize zoned backing devices
>   block/ide/scsi: Set BLK_PERM_SUPPORT_HM_ZONED
>   raw: Don't open ZBDs if backend can't handle them
> 
>  block.c                   | 15 +++++++
>  block/file-posix.c        | 89 +++++++++++++++++++++++++++++++++------
>  block/io.c                |  5 +++
>  hw/block/block.c          |  8 +++-
>  hw/block/fdc.c            |  5 ++-
>  hw/block/nvme.c           |  2 +-
>  hw/block/virtio-blk.c     |  2 +-
>  hw/block/xen-block.c      |  2 +-
>  hw/ide/qdev.c             |  2 +-
>  hw/scsi/scsi-disk.c       | 13 +++---
>  hw/scsi/scsi-generic.c    |  2 +-
>  hw/usb/dev-storage.c      |  2 +-
>  include/block/block.h     | 19 ++++++++-
>  include/block/block_int.h |  3 ++
>  include/hw/block/block.h  |  3 +-
>  15 files changed, 141 insertions(+), 31 deletions(-)
> 
> -- 
> 2.21.0
> 

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>