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[Qemu-devel] [PATCH v3 00/29] block: Support for 512b-on-4k emulation
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH v3 00/29] block: Support for 512b-on-4k emulation |
Date: |
Fri, 17 Jan 2014 15:14:50 +0100 |
This patch series adds code to the block layer that allows performing
I/O requests in smaller granularities than required by the host backend
(most importantly, O_DIRECT restrictions). It achieves this for reads
by rounding the request to host-side block boundary, and for writes by
performing a read-modify-write cycle (and serialising requests
touching the same block so that the RMW doesn't write back stale data).
Originally I intended to reuse a lot of code from Paolo's previous
patch series, however as I tried to integrate pread/pwrite, which
already do a very similar thing (except for considering concurrency),
and because I wanted to implement zero-copy, most of this series ended
up being new code.
Zero-copy is possible in a common case because while XFS defauls to a
4k sector size and therefore 4k on-disk O_DIRECT alignment for 512E
disks, it still only has a 512 byte memory alignment requirement.
(Unfortunately the XFS_IOC_DIOINFO ioctl claims 4k even for memory, but
we know that the value is wrong and can probe it.)
Changes in v2 -> v3:
- Fixed I/O throttling bypass by converting to byte granularity [Wenchao]
- Made 'bytes' argument to tracked_request_overlaps() unsigned [Max]
- Fixed a corruption bug that came from using outdated RMW buffers after
waiting for another request and added some assertions to check the
assumptions [Peter]
- Fixed bytes vs. sectors error in zero-after-EOF code of
bdrv_co_do_preadv [Max]
- Removed orphaned protoype in block.h [Max]
- A qemu-iotests case and some infrastructure to support it
Changes in v1 -> v2:
- Fixed overlap_bytes calculation in mark_request_serialising()
- Fixed wait_serialising_requests() deadlock
- iscsi: Set bs->request_alignment [Peter]
- iscsi: Query block limits only in iscsi_open() when no other request
are in flight, and in iscsi_refresh_limits() copy the stored values
into bs->bl [Peter]
Changes in RFC -> v1:
- Moved opt_mem_alignment into BlockLimits [Paolo]
- Changed BlockLimits in turn to work a bit more like the
.bdrv_opt_mem_align() callback of the RFC; allows updating the
BlockLimits later when the chain changes or bdrv_reopen() toggles
O_DIRECT
- Fixed a typo in a commit message [Eric]
Kevin Wolf (26):
block: Move initialisation of BlockLimits to bdrv_refresh_limits()
block: Inherit opt_transfer_length
block: Update BlockLimits when they might have changed
qemu_memalign: Allow small alignments
block: Detect unaligned length in bdrv_qiov_is_aligned()
block: Don't use guest sector size for qemu_blockalign()
block: Introduce bdrv_aligned_preadv()
block: Introduce bdrv_co_do_preadv()
block: Introduce bdrv_aligned_pwritev()
block: write: Handle COR dependency after I/O throttling
block: Introduce bdrv_co_do_pwritev()
block: Switch BdrvTrackedRequest to byte granularity
block: Allow waiting for overlapping requests between begin/end
block: Make zero-after-EOF work with larger alignment
block: Generalise and optimise COR serialisation
block: Make overlap range for serialisation dynamic
block: Allow wait_serialising_requests() at any point
block: Align requests in bdrv_co_do_pwritev()
block: Assert serialisation assumptions in pwritev
block: Change coroutine wrapper to byte granularity
block: Make bdrv_pread() a bdrv_prwv_co() wrapper
block: Make bdrv_pwrite() a bdrv_prwv_co() wrapper
blkdebug: Make required alignment configurable
qemu-io: New command 'sleep'
qemu-iotests: Test pwritev RMW logic
block: Switch bdrv_io_limits_intercept() to byte granularity
Paolo Bonzini (3):
block: rename buffer_alignment to guest_block_size
raw: Probe required direct I/O alignment
iscsi: Set bs->request_alignment
block.c | 644 +++++++++++++++++++++++++++++++--------------
block/backup.c | 7 +-
block/blkdebug.c | 24 ++
block/iscsi.c | 47 ++--
block/qcow2.c | 11 +-
block/qed.c | 11 +-
block/raw-posix.c | 102 +++++--
block/raw-win32.c | 41 +++
block/stream.c | 2 +
block/vmdk.c | 22 +-
hw/block/virtio-blk.c | 2 +-
hw/ide/core.c | 2 +-
hw/scsi/scsi-disk.c | 2 +-
hw/scsi/scsi-generic.c | 2 +-
include/block/block.h | 15 +-
include/block/block_int.h | 27 +-
qemu-io-cmds.c | 42 +++
tests/qemu-iotests/077 | 278 +++++++++++++++++++
tests/qemu-iotests/077.out | 202 ++++++++++++++
tests/qemu-iotests/group | 1 +
util/oslib-posix.c | 5 +
21 files changed, 1234 insertions(+), 255 deletions(-)
create mode 100755 tests/qemu-iotests/077
create mode 100644 tests/qemu-iotests/077.out
--
1.8.1.4