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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>
This commit is contained in:
Kevin Wolf
2016-06-03 17:36:27 +02:00
parent 2174f12bde
commit 9d52aa3c38
3 changed files with 26 additions and 27 deletions
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7
block/linux-aio.c
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@ -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,