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[Qemu-block] [PULL 04/37] null: Switch to byte-based read/write
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 04/37] null: Switch to byte-based read/write |
Date: |
Tue, 15 May 2018 17:40:00 +0200 |
From: Eric Blake <address@hidden>
We are gradually moving away from sector-based interfaces, towards
byte-based. Make the change for the last few sector-based callbacks
in the null-co and null-aio drivers.
Note that since the null driver does nothing on writes, it trivially
supports the BDRV_REQ_FUA flag (all writes have already landed to
the same bit-bucket without needing an extra flush call). Also, since
the null driver does just as well with byte-based requests, we can
now avoid cycles wasted on read-modify-write by taking advantage of
the block layer now defaulting the alignment to 1 instead of 512.
Signed-off-by: Eric Blake <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block/null.c | 45 +++++++++++++++++++++++----------------------
1 file changed, 23 insertions(+), 22 deletions(-)
diff --git a/block/null.c b/block/null.c
index 3944550f67..5d610fdfba 100644
--- a/block/null.c
+++ b/block/null.c
@@ -93,6 +93,7 @@ static int null_file_open(BlockDriverState *bs, QDict
*options, int flags,
}
s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false);
qemu_opts_del(opts);
+ bs->supported_write_flags = BDRV_REQ_FUA;
return ret;
}
@@ -116,22 +117,22 @@ static coroutine_fn int null_co_common(BlockDriverState
*bs)
return 0;
}
-static coroutine_fn int null_co_readv(BlockDriverState *bs,
- int64_t sector_num, int nb_sectors,
- QEMUIOVector *qiov)
+static coroutine_fn int null_co_preadv(BlockDriverState *bs,
+ uint64_t offset, uint64_t bytes,
+ QEMUIOVector *qiov, int flags)
{
BDRVNullState *s = bs->opaque;
if (s->read_zeroes) {
- qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE);
+ qemu_iovec_memset(qiov, 0, 0, bytes);
}
return null_co_common(bs);
}
-static coroutine_fn int null_co_writev(BlockDriverState *bs,
- int64_t sector_num, int nb_sectors,
- QEMUIOVector *qiov)
+static coroutine_fn int null_co_pwritev(BlockDriverState *bs,
+ uint64_t offset, uint64_t bytes,
+ QEMUIOVector *qiov, int flags)
{
return null_co_common(bs);
}
@@ -186,26 +187,26 @@ static inline BlockAIOCB
*null_aio_common(BlockDriverState *bs,
return &acb->common;
}
-static BlockAIOCB *null_aio_readv(BlockDriverState *bs,
- int64_t sector_num, QEMUIOVector *qiov,
- int nb_sectors,
- BlockCompletionFunc *cb,
- void *opaque)
+static BlockAIOCB *null_aio_preadv(BlockDriverState *bs,
+ uint64_t offset, uint64_t bytes,
+ QEMUIOVector *qiov, int flags,
+ BlockCompletionFunc *cb,
+ void *opaque)
{
BDRVNullState *s = bs->opaque;
if (s->read_zeroes) {
- qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE);
+ qemu_iovec_memset(qiov, 0, 0, bytes);
}
return null_aio_common(bs, cb, opaque);
}
-static BlockAIOCB *null_aio_writev(BlockDriverState *bs,
- int64_t sector_num, QEMUIOVector *qiov,
- int nb_sectors,
- BlockCompletionFunc *cb,
- void *opaque)
+static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs,
+ uint64_t offset, uint64_t bytes,
+ QEMUIOVector *qiov, int flags,
+ BlockCompletionFunc *cb,
+ void *opaque)
{
return null_aio_common(bs, cb, opaque);
}
@@ -265,8 +266,8 @@ static BlockDriver bdrv_null_co = {
.bdrv_close = null_close,
.bdrv_getlength = null_getlength,
- .bdrv_co_readv = null_co_readv,
- .bdrv_co_writev = null_co_writev,
+ .bdrv_co_preadv = null_co_preadv,
+ .bdrv_co_pwritev = null_co_pwritev,
.bdrv_co_flush_to_disk = null_co_flush,
.bdrv_reopen_prepare = null_reopen_prepare,
@@ -285,8 +286,8 @@ static BlockDriver bdrv_null_aio = {
.bdrv_close = null_close,
.bdrv_getlength = null_getlength,
- .bdrv_aio_readv = null_aio_readv,
- .bdrv_aio_writev = null_aio_writev,
+ .bdrv_aio_preadv = null_aio_preadv,
+ .bdrv_aio_pwritev = null_aio_pwritev,
.bdrv_aio_flush = null_aio_flush,
.bdrv_reopen_prepare = null_reopen_prepare,
--
2.13.6
- [Qemu-block] [PULL 00/37] Block layer patches, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 04/37] null: Switch to byte-based read/write,
Kevin Wolf <=
- [Qemu-block] [PULL 03/37] file-win32: Switch to byte-based callbacks, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 02/37] block: Support byte-based aio callbacks, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 05/37] rbd: Switch to byte-based callbacks, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 06/37] vxhs: Switch to byte-based callbacks, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 07/37] block: Drop last of the sector-based aio callbacks, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 08/37] block: Merge .bdrv_co_writev{, _flags} in drivers, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 09/37] hmp: Allow using a qdev id in block_set_io_throttle, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 01/37] block-backend: simplify blk_get_aio_context, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 10/37] blockjob: expose error string via query, Kevin Wolf, 2018/05/15
- [Qemu-block] [PULL 15/37] blockjob: Introduce block_job_ratelimit_get_delay(), Kevin Wolf, 2018/05/15