On Sun, Dec 27, 2020 at 11:42 AM Peter Lieven <p...@kamp.de> wrote:
>
> Signed-off-by: Peter Lieven <p...@kamp.de>
> ---
> block/rbd.c | 31 ++++++++++++++++++++++++++++++-
> 1 file changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/block/rbd.c b/block/rbd.c
> index 2d77d0007f..27b4404adf 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -63,7 +63,8 @@ typedef enum {
> RBD_AIO_READ,
> RBD_AIO_WRITE,
> RBD_AIO_DISCARD,
> - RBD_AIO_FLUSH
> + RBD_AIO_FLUSH,
> + RBD_AIO_WRITE_ZEROES
> } RBDAIOCmd;
>
> typedef struct BDRVRBDState {
> @@ -221,8 +222,12 @@ done:
>
> static void qemu_rbd_refresh_limits(BlockDriverState *bs, Error **errp)
> {
> + BDRVRBDState *s = bs->opaque;
> /* XXX Does RBD support AIO on less than 512-byte alignment? */
> bs->bl.request_alignment = 512;
> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
> + bs->bl.pwrite_zeroes_alignment = s->object_size;
The optimal alignment is 512 bytes -- but it can safely work just fine
down to 1 byte alignment since it will pad the request with additional
writes if needed.
> +#endif
> }
>
>
> @@ -695,6 +700,9 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict
> *options, int flags,
> }
>
> s->aio_context = bdrv_get_aio_context(bs);
> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
> + bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP;
> +#endif
>
> /* When extending regular files, we get zeros from the OS */
> bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
> @@ -808,6 +816,11 @@ static int coroutine_fn
> qemu_rbd_start_co(BlockDriverState *bs,
> case RBD_AIO_FLUSH:
> r = rbd_aio_flush(s->image, c);
> break;
> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
> + case RBD_AIO_WRITE_ZEROES:
> + r = rbd_aio_write_zeroes(s->image, offset, bytes, c, 0, 0);
> + break;
> +#endif
> default:
> r = -EINVAL;
> }
> @@ -880,6 +893,19 @@ static int coroutine_fn
> qemu_rbd_co_pdiscard(BlockDriverState *bs,
> return qemu_rbd_start_co(bs, offset, count, NULL, 0, RBD_AIO_DISCARD);
> }
>
> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
> +static int
> +coroutine_fn qemu_rbd_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
> + int count, BdrvRequestFlags flags)
> +{
> + if (!(flags & BDRV_REQ_MAY_UNMAP)) {
> + return -ENOTSUP;
> + }
There is a "RBD_WRITE_ZEROES_FLAG_THICK_PROVISION" flag that you can
use to optionally disable unmap.
> + return qemu_rbd_start_co(bs, offset, count, NULL, flags,
> + RBD_AIO_WRITE_ZEROES);
> +}
> +#endif
> +
> static int qemu_rbd_getinfo(BlockDriverState *bs, BlockDriverInfo *bdi)
> {
> BDRVRBDState *s = bs->opaque;
> @@ -1108,6 +1134,9 @@ static BlockDriver bdrv_rbd = {
> .bdrv_co_pwritev = qemu_rbd_co_pwritev,
> .bdrv_co_flush_to_disk = qemu_rbd_co_flush,
> .bdrv_co_pdiscard = qemu_rbd_co_pdiscard,
> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
> + .bdrv_co_pwrite_zeroes = qemu_rbd_co_pwrite_zeroes,
> +#endif
>
> .bdrv_snapshot_create = qemu_rbd_snap_create,
> .bdrv_snapshot_delete = qemu_rbd_snap_remove,
> --
> 2.17.1
>
>
--
Jason
