[0/4] SCSI COMPARE_AND_WRITE support

Message

Yaowei Bai Oct. 25, 2019, 9:35 a.m. UTC

Recently ceph/librbd added several interfaces to handle SCSI commands like
COMPARE_AND_WRITE directly. However they were only be used in special
scenarios, i.e. ISCSI. That involves more software components which makes
the IO path longer and could bring more potential issues. Actually we're
maintaining several ceph clusters with ISCSI protocal being used which,
i have to say, is not an easy job.

So supporting COMPARE_AND_WRITE in scsi-disk would be a reasonable solution
and easy to implement with the help of the SCSI handlers in librbd, which
could leave alone the ISCSI stuff and make the IO path shorter.

This patchset implements it by reusing the blk_aio_pwritev interface and
introducing a new BDRV_REQ_COMPARE_AND_WRITE element into BdrvRequestFlags
to indicate a COMPARE_AND_WRITE request, rather than adding a new interface
into block-backend.c.

The FUA support is implemented in the blk_aio_pwritev's callback function
similar to its emulation in scsi_write_do_fua function, maybe through
BDRV_REQ_FUA is another doable way.

This patchset is tested with the method of sg_compare_and_write.txt from
sg3_utils. Link below:

https://github.com/hreinecke/sg3_utils/blob/master/examples/sg_compare_and_write.txt

Yaowei Bai (4):
  block: add SCSI COMPARE_AND_WRITE support
  block/rbd: implement bdrv_aio_compare_and_write interface
  hw/scsi: add SCSI COMPARE_AND_WRITE support
  scsi-disk: add FUA support for COMPARE_AND_WRITE

 block/io.c                  | 20 +++++++++
 block/raw-format.c          |  3 +-
 block/rbd.c                 | 41 ++++++++++++++++++-
 hw/scsi/emulation.c         |  1 +
 hw/scsi/scsi-bus.c          |  4 ++
 hw/scsi/scsi-disk.c         | 98 +++++++++++++++++++++++++++++++++++++++++++++
 hw/scsi/trace-events        |  1 +
 include/block/block.h       |  5 ++-
 include/block/block_int.h   |  3 ++
 include/hw/scsi/emulation.h |  3 ++
 include/scsi/utils.h        |  2 +
 include/tcmu/tcmu.h         | 14 +++++++
 scsi/utils.c                |  5 +++
 13 files changed, 195 insertions(+), 5 deletions(-)
 create mode 100644 include/tcmu/tcmu.h

Comments

[e-mail] Oct. 25, 2019, 11:38 p.m. UTC | #1

Patchew URL: https://patchew.org/QEMU/[e-mail]/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Subject: [PATCH 0/4] SCSI COMPARE_AND_WRITE support
Type: series
Message-id: [e-mail]

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

Switched to a new branch 'test'
9dec556 scsi-disk: add FUA support for COMPARE_AND_WRITE
8ee0b25 hw/scsi: add SCSI COMPARE_AND_WRITE support
6c2bd51 block/rbd: implement bdrv_aio_compare_and_write interface
f2cafca block: add SCSI COMPARE_AND_WRITE support

=== OUTPUT BEGIN ===
1/4 Checking commit f2cafca98400 (block: add SCSI COMPARE_AND_WRITE support)
2/4 Checking commit 6c2bd51ede14 (block/rbd: implement bdrv_aio_compare_and_write interface)
ERROR: braces {} are necessary for all arms of this statement
#59: FILE: block/rbd.c:808:
+    if (LIBRBD_HAVE_COMPARE_AND_WRITE)
[...]

ERROR: line over 90 characters
#87: FILE: block/rbd.c:1015:
+        r = rbd_aio_compare_and_write(s->image, off, size/2, rcb->buf, (rcb->buf + size/2), c, 0, 0);

ERROR: spaces required around that '/' (ctx:VxV)
#87: FILE: block/rbd.c:1015:
+        r = rbd_aio_compare_and_write(s->image, off, size/2, rcb->buf, (rcb->buf + size/2), c, 0, 0);
                                                          ^

ERROR: spaces required around that '/' (ctx:VxV)
#87: FILE: block/rbd.c:1015:
+        r = rbd_aio_compare_and_write(s->image, off, size/2, rcb->buf, (rcb->buf + size/2), c, 0, 0);
                                                                                        ^

WARNING: line over 80 characters
#98: FILE: block/rbd.c:1082:
+                                                  uint64_t offset, uint64_t bytes,

total: 4 errors, 1 warnings, 90 lines checked

Patch 2/4 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

3/4 Checking commit 8ee0b25d3d83 (hw/scsi: add SCSI COMPARE_AND_WRITE support)
WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
#219: 
new file mode 100644

total: 0 errors, 1 warnings, 190 lines checked

Patch 3/4 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.
4/4 Checking commit 9dec556b752c (scsi-disk: add FUA support for COMPARE_AND_WRITE)
=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/[e-mail]/testing.checkpatch/?type=message.
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