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raw-posix: Implement .bdrv_co_preadv/pwritev
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The raw-posix block driver actually supports byte-aligned requests now
on non-O_DIRECT images, like it already (and previously incorrectly)
claimed in bs->request_alignment.

For some block drivers this means that a RMW cycle can be avoided when
they write sub-sector metadata e.g. for cluster allocation.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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@kevmw
kevmw committed Jun 16, 2016
1 parent 2174f12 commit 9d52aa3
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Showing 3 changed files with 26 additions and 27 deletions.
7 changes: 2 additions & 5 deletions block/linux-aio.c
View file
Expand Up @@ -271,15 +271,12 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
}

int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
int64_t sector_num, QEMUIOVector *qiov,
int nb_sectors, int type)
uint64_t offset, QEMUIOVector *qiov, int type)
{
off_t offset = sector_num * BDRV_SECTOR_SIZE;
int ret;

struct qemu_laiocb laiocb = {
.co = qemu_coroutine_self(),
.nbytes = nb_sectors * BDRV_SECTOR_SIZE,
.nbytes = qiov->size,
.ctx = s,
.is_read = (type == QEMU_AIO_READ),
.qiov = qiov,
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3 changes: 1 addition & 2 deletions block/raw-aio.h
View file
Expand Up @@ -40,8 +40,7 @@ typedef struct LinuxAioState LinuxAioState;
LinuxAioState *laio_init(void);
void laio_cleanup(LinuxAioState *s);
int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
int64_t sector_num, QEMUIOVector *qiov,
int nb_sectors, int type);
uint64_t offset, QEMUIOVector *qiov, int type);
BlockAIOCB *laio_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque, int type);
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43 changes: 23 additions & 20 deletions block/raw-posix.c
View file
Expand Up @@ -1325,8 +1325,8 @@ static BlockAIOCB *paio_submit(BlockDriverState *bs, int fd,
return thread_pool_submit_aio(pool, aio_worker, acb, cb, opaque);
}

static int coroutine_fn raw_co_rw(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov, int type)
static int coroutine_fn raw_co_prw(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int type)
{
BDRVRawState *s = bs->opaque;

Expand All @@ -1344,26 +1344,28 @@ static int coroutine_fn raw_co_rw(BlockDriverState *bs, int64_t sector_num,
type |= QEMU_AIO_MISALIGNED;
#ifdef CONFIG_LINUX_AIO
} else if (s->use_aio) {
return laio_co_submit(bs, s->aio_ctx, s->fd, sector_num, qiov,
nb_sectors, type);
assert(qiov->size == bytes);
return laio_co_submit(bs, s->aio_ctx, s->fd, offset, qiov, type);
#endif
}
}

return paio_submit_co(bs, s->fd, sector_num * BDRV_SECTOR_SIZE, qiov,
nb_sectors * BDRV_SECTOR_SIZE, type);
return paio_submit_co(bs, s->fd, offset, qiov, bytes, type);
}

static int coroutine_fn raw_co_readv(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
static int coroutine_fn raw_co_preadv(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov,
int flags)
{
return raw_co_rw(bs, sector_num, nb_sectors, qiov, QEMU_AIO_READ);
return raw_co_prw(bs, offset, bytes, qiov, QEMU_AIO_READ);
}

static int coroutine_fn raw_co_writev(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov,
int flags)
{
return raw_co_rw(bs, sector_num, nb_sectors, qiov, QEMU_AIO_WRITE);
assert(flags == 0);
return raw_co_prw(bs, offset, bytes, qiov, QEMU_AIO_WRITE);
}

static void raw_aio_plug(BlockDriverState *bs)
Expand Down Expand Up @@ -1952,8 +1954,8 @@ BlockDriver bdrv_file = {
.bdrv_co_get_block_status = raw_co_get_block_status,
.bdrv_co_pwrite_zeroes = raw_co_pwrite_zeroes,

.bdrv_co_readv = raw_co_readv,
.bdrv_co_writev = raw_co_writev,
.bdrv_co_preadv = raw_co_preadv,
.bdrv_co_pwritev = raw_co_pwritev,
.bdrv_aio_flush = raw_aio_flush,
.bdrv_aio_discard = raw_aio_discard,
.bdrv_refresh_limits = raw_refresh_limits,
Expand Down Expand Up @@ -2400,8 +2402,8 @@ static BlockDriver bdrv_host_device = {
.create_opts = &raw_create_opts,
.bdrv_co_pwrite_zeroes = hdev_co_pwrite_zeroes,

.bdrv_co_readv = raw_co_readv,
.bdrv_co_writev = raw_co_writev,
.bdrv_co_preadv = raw_co_preadv,
.bdrv_co_pwritev = raw_co_pwritev,
.bdrv_aio_flush = raw_aio_flush,
.bdrv_aio_discard = hdev_aio_discard,
.bdrv_refresh_limits = raw_refresh_limits,
Expand Down Expand Up @@ -2530,8 +2532,9 @@ static BlockDriver bdrv_host_cdrom = {
.bdrv_create = hdev_create,
.create_opts = &raw_create_opts,

.bdrv_co_readv = raw_co_readv,
.bdrv_co_writev = raw_co_writev,

.bdrv_co_preadv = raw_co_preadv,
.bdrv_co_pwritev = raw_co_pwritev,
.bdrv_aio_flush = raw_aio_flush,
.bdrv_refresh_limits = raw_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
Expand Down Expand Up @@ -2665,8 +2668,8 @@ static BlockDriver bdrv_host_cdrom = {
.bdrv_create = hdev_create,
.create_opts = &raw_create_opts,

.bdrv_co_readv = raw_co_readv,
.bdrv_co_writev = raw_co_writev,
.bdrv_co_preadv = raw_co_preadv,
.bdrv_co_pwritev = raw_co_pwritev,
.bdrv_aio_flush = raw_aio_flush,
.bdrv_refresh_limits = raw_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
Expand Down

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