On Tue, Apr 24, 2018 at 3:25 PM, Eric Blake <ebl...@redhat.com> wrote:
> We are gradually moving away from sector-based interfaces, towards
> byte-based. Make the change for the last few sector-based callbacks
> in the rbd driver.
>
> Note that the driver was already using byte-based calls for
> performing actual I/O, so this just gets rid of a round trip
> of scaling; however, as I don't know if RBD is tolerant of
> non-sector AIO operations, I went with the conservate approach
> of adding .bdrv_refresh_limits to override the block layer
> defaults back to the pre-patch value of 512.
>
> Signed-off-by: Eric Blake <ebl...@redhat.com>
>
> ---
> v2: override new block layer default alignment [Kevin]
> ---
> block/rbd.c | 44 ++++++++++++++++++++++++--------------------
> 1 file changed, 24 insertions(+), 20 deletions(-)
>
> diff --git a/block/rbd.c b/block/rbd.c
> index c9359d0ad84..638ecf8d986 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -231,6 +231,13 @@ done:
> }
>
>
> +static void qemu_rbd_refresh_limits(BlockDriverState *bs, Error **errp)
> +{
> + /* XXX Does RBD support AIO on less than 512-byte alignment? */
Yes, librbd internally supports 1-byte alignment for IO, but the
optimal alignment/length would be object size * stripe count.
> + bs->bl.request_alignment = 512;
> +}
> +
> +
> static int qemu_rbd_set_auth(rados_t cluster, const char *secretid,
> Error **errp)
> {
> @@ -899,27 +906,23 @@ failed:
> return NULL;
> }
>
> -static BlockAIOCB *qemu_rbd_aio_readv(BlockDriverState *bs,
> - int64_t sector_num,
> - QEMUIOVector *qiov,
> - int nb_sectors,
> - BlockCompletionFunc *cb,
> - void *opaque)
> -{
> - return rbd_start_aio(bs, sector_num << BDRV_SECTOR_BITS, qiov,
> - (int64_t) nb_sectors << BDRV_SECTOR_BITS, cb,
> opaque,
> - RBD_AIO_READ);
> -}
> -
> -static BlockAIOCB *qemu_rbd_aio_writev(BlockDriverState *bs,
> - int64_t sector_num,
> - QEMUIOVector *qiov,
> - int nb_sectors,
> +static BlockAIOCB *qemu_rbd_aio_preadv(BlockDriverState *bs,
> + uint64_t offset, uint64_t bytes,
> + QEMUIOVector *qiov, int flags,
> BlockCompletionFunc *cb,
> void *opaque)
> {
> - return rbd_start_aio(bs, sector_num << BDRV_SECTOR_BITS, qiov,
> - (int64_t) nb_sectors << BDRV_SECTOR_BITS, cb,
> opaque,
> + return rbd_start_aio(bs, offset, qiov, bytes, cb, opaque,
> + RBD_AIO_READ);
> +}
> +
> +static BlockAIOCB *qemu_rbd_aio_pwritev(BlockDriverState *bs,
> + uint64_t offset, uint64_t bytes,
> + QEMUIOVector *qiov, int flags,
> + BlockCompletionFunc *cb,
> + void *opaque)
> +{
> + return rbd_start_aio(bs, offset, qiov, bytes, cb, opaque,
> RBD_AIO_WRITE);
> }
>
> @@ -1158,6 +1161,7 @@ static BlockDriver bdrv_rbd = {
> .format_name = "rbd",
> .instance_size = sizeof(BDRVRBDState),
> .bdrv_parse_filename = qemu_rbd_parse_filename,
> + .bdrv_refresh_limits = qemu_rbd_refresh_limits,
> .bdrv_file_open = qemu_rbd_open,
> .bdrv_close = qemu_rbd_close,
> .bdrv_reopen_prepare = qemu_rbd_reopen_prepare,
> @@ -1170,8 +1174,8 @@ static BlockDriver bdrv_rbd = {
> .bdrv_truncate = qemu_rbd_truncate,
> .protocol_name = "rbd",
>
> - .bdrv_aio_readv = qemu_rbd_aio_readv,
> - .bdrv_aio_writev = qemu_rbd_aio_writev,
> + .bdrv_aio_preadv = qemu_rbd_aio_preadv,
> + .bdrv_aio_pwritev = qemu_rbd_aio_pwritev,
>
> #ifdef LIBRBD_SUPPORTS_AIO_FLUSH
> .bdrv_aio_flush = qemu_rbd_aio_flush,
> --
> 2.14.3
>
>
--
Jason
