This patch series adds a new extension - zoned format - to the
qcow2 driver, allowing full zoned storage emulation on a qcow2
image file. A user can attach such an image to a guest and have
it appear as a host-managed zoned block device.
The zoned format is opt-in through a new qcow2 header extension
that pins the zone geometry. Behind the extension is a dedicated
zoned metadata region that stores one 8-byte write pointer (WP)
per zone. The extension is gated by an incompatible bit, so an
older qcow2 implementation cannot accidentally open the image.
Each write pointer is routed through the write pointer cache,
a Qcow2Cache object. The write pointer cache is written to disk
after the qcow2 metadata is written, thus guaranteeing that
the write pointer is updated after the corresponding data is
written.
Zone states are in memory. Read-only and offline states are
device-internal events, which are not modelled in qcow2
emulation for simplicity. The other zone states
(closed, empty, full) can be inferred from write pointer
values, persistent across QEMU reboots. The open states are
kept in memory using open zone lists.
To create a qcow2 file with the zoned format:
qemu-img create -f qcow2 zbc.qcow2 \
-o size=768M \
-o zone.size=64M \
-o zone.capacity=64M \
-o zone.conventional_zones=0 \
-o zone.max_open_zones=6 \
-o zone.max_active_zones=8 \
-o zone.mode=host-managed
Then attach it to a guest via the QEMU command line:
-blockdev
node-name=drive1,driver=qcow2,file.driver=file,file.filename=zbc.qcow2 \
-device virtio-blk-pci,drive=drive1 \
Tested with blktests, fio, zbd_state (an internal test suite) and
zonefs, comparing a zoned qcow2 image attached via virtio-blk with
zloop, null_blk and scsi_debug (passed/failed/skipped):
+--------------------+----------+---------+-----------+---------+
| Testrun | blktests | fio | zbd_state | zonefs |
+--------------------+----------+---------+-----------+---------+
| zloop | 9/0/10 | 57/0/18 | 29/0/8 | 113/0/0 |
| null_blk | 9/0/10 | 57/0/18 | 29/0/8 | 113/0/0 |
| scsi_debug | 10/0/12 | 61/0/14 | 29/0/8 | 113/0/0 |
| virtio-blk + qcow2 | 9/0/10 | 57/0/18 | 29/0/8 | 113/0/0 |
+--------------------+----------+---------+-----------+---------+
The last two patches are not used by the qcow2 driver. Both Daejun
Park's zoned UFS series and an upcoming series that adds zoned support
to ATA depend on this series, and both also require these two patches,
so they are included here, to avoid both series needing to carry them
separately as dependencies.
Git branch can be found at:
https://github.com/floatious/qemu/tree/qcow2-v16
v15->v16:
- rebase on master, which now contains the series "block: fix the zone
write granularity and the zone append limit"
- report a write to a full zone with a dedicated errno, BLK_ZE_FULL
(EXFULL), as ZAC, ZBC, NVMe ZNS and virtio-blk all report it
differently from a write that is not at the write pointer; virtio-blk
reports it as VIRTIO_BLK_S_ZONE_INVALID_CMD (pointed out by Daejun
Park)
- refuse the management of a conventional zone with EINVAL instead of
EIO
- trace rejected zone requests instead of reporting them with
error_report(), which a guest could use to flood stderr (pointed out
by Daejun Park)
- add "block: add accessors for the zone model, capacity and open zone
limit" and "scsi: add the sense codes of zoned block devices" (new
patches), for the zoned UFS and zoned ATA series
Niklas Cassel (5):
block: define errnos for zone protocol errors
qcow2: validate the write pointer table when opening an image
virtio-blk: report zone errors with their zone status codes
block: add accessors for the zone model, capacity and open zone limit
scsi: add the sense codes of zoned block devices
Sam Li (4):
docs/qcow2: add the zoned format feature
qcow2: add configurations for zoned format extension
qcow2: add zoned emulation capability
iotests: test the zoned format feature for qcow2 file
MAINTAINERS | 1 +
block/block-backend.c | 33 +
block/io.c | 13 +-
block/qcow2-cache.c | 11 +-
block/qcow2-refcount.c | 18 +
block/qcow2.c | 1674 ++++++++++++++++-
block/qcow2.h | 86 +-
block/trace-events | 10 +
docs/interop/qcow2.rst | 115 +-
docs/system/qemu-block-drivers.rst.inc | 44 +
hw/block/block.c | 7 +
hw/block/virtio-blk.c | 49 +-
include/block/block-common.h | 17 +
include/block/block-io.h | 6 +
include/block/block_int-common.h | 12 +
include/qemu/osdep.h | 6 +
include/scsi/utils.h | 6 +
include/system/block-backend-io.h | 3 +
qapi/block-core.json | 86 +-
scsi/utils.c | 15 +
tests/qemu-iotests/031.out | 8 +-
tests/qemu-iotests/036.out | 4 +-
tests/qemu-iotests/061.out | 14 +-
tests/qemu-iotests/082.out | 108 ++
tests/qemu-iotests/303.out | 4 +-
tests/qemu-iotests/tests/qcow2-encryption.out | 4 +-
tests/qemu-iotests/tests/zoned-qcow2 | 362 ++++
tests/qemu-iotests/tests/zoned-qcow2.out | 258 +++
28 files changed, 2937 insertions(+), 37 deletions(-)
create mode 100755 tests/qemu-iotests/tests/zoned-qcow2
create mode 100644 tests/qemu-iotests/tests/zoned-qcow2.out
base-commit: 9703b6cf418d2ce72fae8d00e511135ce0bfda43
--
2.56.0
