Re: [Qemu-devel] [RFC v5] RBD: Add support readv,writev for rbd

[Jason Dillaman]

On Thu, Feb 16, 2017 at 4:00 AM,  <address@hidden> wrote:
> From: tianqing <address@hidden>
>
> Rbd can do readv and writev directly, so wo do not need to transform
> iov to buf or vice versa any more.
>
> Signed-off-by: tianqing <address@hidden>
> ---
>  block/rbd.c | 49 ++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 42 insertions(+), 7 deletions(-)
>
> diff --git a/block/rbd.c b/block/rbd.c
> index a57b3e3..75ae1d6 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -47,7 +47,7 @@
>   */
>
>  /* rbd_aio_discard added in 0.1.2 */
> -#if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(0, 1, 2)
> +#if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(12, 0, 0)
>  #define LIBRBD_SUPPORTS_DISCARD
>  #else
>  #undef LIBRBD_SUPPORTS_DISCARD

Do not change this -- discard support is available in very old
versions of librbd not just the future Luminous release.

> @@ -73,7 +73,12 @@ typedef struct RBDAIOCB {
>      BlockAIOCB common;
>      int64_t ret;
>      QEMUIOVector *qiov;
> +/* Note:
> + * The LIBRBD_SUPPORTS_IOVEC is defined in librbd.h.
> + */
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>      char *bounce;
> +#endif
>      RBDAIOCmd cmd;
>      int error;
>      struct BDRVRBDState *s;
> @@ -83,7 +88,9 @@ typedef struct RADOSCB {
>      RBDAIOCB *acb;
>      struct BDRVRBDState *s;
>      int64_t size;
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>      char *buf;
> +#endif
>      int64_t ret;
>  } RADOSCB;
>
> @@ -426,11 +433,21 @@ static void qemu_rbd_complete_aio(RADOSCB *rcb)
>          }
>      } else {
>          if (r < 0) {
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>              memset(rcb->buf, 0, rcb->size);
> +#else
> +            iov_memset(acb->qiov->iov, acb->qiov->niov, 0, 0, 
> acb->qiov->size);
> +#endif
>              acb->ret = r;
>              acb->error = 1;
>          } else if (r < rcb->size) {
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>              memset(rcb->buf + r, 0, rcb->size - r);
> +#else
> +            iov_memset(acb->qiov->iov, acb->qiov->niov,
> +                       r, 0, acb->qiov->size - r);
> +#endif
> +
>              if (!acb->error) {
>                  acb->ret = rcb->size;
>              }
> @@ -441,10 +458,12 @@ static void qemu_rbd_complete_aio(RADOSCB *rcb)
>
>      g_free(rcb);
>
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>      if (acb->cmd == RBD_AIO_READ) {
>          qemu_iovec_from_buf(acb->qiov, 0, acb->bounce, acb->qiov->size);
>      }
>      qemu_vfree(acb->bounce);
> +#endif
>      acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));
>
>      qemu_aio_unref(acb);
> @@ -655,8 +674,10 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>      RBDAIOCB *acb;
>      RADOSCB *rcb = NULL;
>      rbd_completion_t c;
> -    char *buf;
>      int r;
> +#ifndef LIBRBD_SUPPORTS_IOVEC
> +    char *buf = NULL;
> +#endif
>
>      BDRVRBDState *s = bs->opaque;
>
> @@ -664,6 +685,8 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>      acb->cmd = cmd;
>      acb->qiov = qiov;
>      assert(!qiov || qiov->size == size);
> +#ifndef LIBRBD_SUPPORTS_IOVEC
> +
>      if (cmd == RBD_AIO_DISCARD || cmd == RBD_AIO_FLUSH) {
>          acb->bounce = NULL;
>      } else {
> @@ -672,19 +695,21 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>              goto failed;
>          }
>      }
> -    acb->ret = 0;
> -    acb->error = 0;
> -    acb->s = s;
> -
>      if (cmd == RBD_AIO_WRITE) {
>          qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);
>      }
> -
>      buf = acb->bounce;
> +#endif
> +    acb->ret = 0;
> +    acb->error = 0;
> +    acb->s = s;
>
>      rcb = g_new(RADOSCB, 1);
> +
>      rcb->acb = acb;
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>      rcb->buf = buf;
> +#endif
>      rcb->s = acb->s;
>      rcb->size = size;
>      r = rbd_aio_create_completion(rcb, (rbd_callback_t) rbd_finish_aiocb, 
> &c);
> @@ -694,10 +719,18 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>
>      switch (cmd) {
>      case RBD_AIO_WRITE:
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>          r = rbd_aio_write(s->image, off, size, buf, c);
> +#else
> +        r = rbd_aio_writev(s->image, qiov->iov, qiov->niov, off, c);
> +#endif
>          break;
>      case RBD_AIO_READ:
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>          r = rbd_aio_read(s->image, off, size, buf, c);
> +#else
> +        r = rbd_aio_readv(s->image, qiov->iov, qiov->niov, off, c);
> +#endif
>          break;
>      case RBD_AIO_DISCARD:
>          r = rbd_aio_discard_wrapper(s->image, off, size, c);
> @@ -719,7 +752,9 @@ failed_completion:
>      rbd_aio_release(c);
>  failed:
>      g_free(rcb);
> +#ifndef LIBRBD_SUPPORTS_IOVEC
>      qemu_vfree(acb->bounce);
> +#endif
>      qemu_aio_unref(acb);
>      return NULL;
>  }
> --
> 2.10.2
>



-- 
Jason