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Re: [Qemu-block] [PATCH v6 07/20] scsi-disk: Switch to byte-based aio bl
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [PATCH v6 07/20] scsi-disk: Switch to byte-based aio block access |
Date: |
Fri, 6 May 2016 14:50:41 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 05.05.2016 um 01:55 hat Eric Blake geschrieben:
> Sector-based blk_aio_readv() and blk_aio_writev() should die; switch
> to byte-based blk_aio_preadv() and blk_aio_pwritev() instead.
>
> Signed-off-by: Eric Blake <address@hidden>
> ---
> hw/scsi/scsi-disk.c | 31 +++++++++++++++----------------
> 1 file changed, 15 insertions(+), 16 deletions(-)
>
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index 1335392..5d98f7b 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -343,8 +343,9 @@ static void scsi_do_read(SCSIDiskReq *r, int ret)
> n = scsi_init_iovec(r, SCSI_DMA_BUF_SIZE);
> block_acct_start(blk_get_stats(s->qdev.conf.blk), &r->acct,
> n * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ);
If you replace n * BDRV_SECTOR_SIZE here as well, n is unused and can go
away (you actually did that already for writes).
> - r->req.aiocb = blk_aio_readv(s->qdev.conf.blk, r->sector, &r->qiov,
> n,
> - scsi_read_complete, r);
> + r->req.aiocb = blk_aio_preadv(s->qdev.conf.blk,
> + r->sector << BDRV_SECTOR_BITS,
> &r->qiov,
> + 0, scsi_read_complete, r);
> }
>
> done:
> @@ -504,7 +505,6 @@ static void scsi_write_data(SCSIRequest *req)
> {
> SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);
> SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
> - uint32_t n;
>
> /* No data transfer may already be in progress */
> assert(r->req.aiocb == NULL);
> @@ -544,11 +544,11 @@ static void scsi_write_data(SCSIRequest *req)
> r->req.aiocb = dma_blk_write(s->qdev.conf.blk, r->req.sg, r->sector,
> scsi_dma_complete, r);
> } else {
> - n = r->qiov.size / 512;
> block_acct_start(blk_get_stats(s->qdev.conf.blk), &r->acct,
> - n * BDRV_SECTOR_SIZE, BLOCK_ACCT_WRITE);
> - r->req.aiocb = blk_aio_writev(s->qdev.conf.blk, r->sector, &r->qiov,
> n,
> - scsi_write_complete, r);
> + r->qiov.size, BLOCK_ACCT_WRITE);
> + r->req.aiocb = blk_aio_pwritev(s->qdev.conf.blk,
> + r->sector << BDRV_SECTOR_BITS,
> &r->qiov,
> + 0, scsi_write_complete, r);
> }
> }
>
> @@ -1730,13 +1730,11 @@ static void scsi_write_same_complete(void *opaque,
> int ret)
> if (data->iov.iov_len) {
> block_acct_start(blk_get_stats(s->qdev.conf.blk), &r->acct,
> data->iov.iov_len, BLOCK_ACCT_WRITE);
> - /* blk_aio_write doesn't like the qiov size being different from
> - * nb_sectors, make sure they match.
> - */
Wouldn't it be better to update the comment instead of deleting it? If I
understand correctly, this additional qemu_iovec_init_external() is for
the last part of an unaligned WRITE SAME request, where the qiov can
become shorter than in the previous iterations.
> qemu_iovec_init_external(&data->qiov, &data->iov, 1);
> - r->req.aiocb = blk_aio_writev(s->qdev.conf.blk, data->sector,
> - &data->qiov, data->iov.iov_len / 512,
> - scsi_write_same_complete, data);
> + r->req.aiocb = blk_aio_pwritev(s->qdev.conf.blk,
> + data->sector << BDRV_SECTOR_BITS,
> + &data->qiov, 0,
> + scsi_write_same_complete, data);
> return;
> }
Kevin
- [Qemu-block] [PATCH v6 02/20] block: Drop private ioctl-only members of BlockRequest, (continued)
- [Qemu-block] [PATCH v6 02/20] block: Drop private ioctl-only members of BlockRequest, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 03/20] block: Switch blk_read_unthrottled() to byte interface, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 04/20] block: Switch blk_*write_zeroes() to byte interface, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 05/20] block: Introduce byte-based aio read/write, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 06/20] ide: Switch to byte-based aio block access, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 07/20] scsi-disk: Switch to byte-based aio block access, Eric Blake, 2016/05/04
- Re: [Qemu-block] [PATCH v6 07/20] scsi-disk: Switch to byte-based aio block access,
Kevin Wolf <=
- [Qemu-block] [PATCH v6 01/20] block: Allow BDRV_REQ_FUA through blk_pwrite(), Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 08/20] virtio: Switch to byte-based aio block access, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 09/20] xen_disk: Switch to byte-based aio block access, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 10/20] fdc: Switch to byte-based block access, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 11/20] nand: Switch to byte-based block access, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 12/20] onenand: Switch to byte-based block access, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 16/20] atapi: Switch to byte-based block access, Eric Blake, 2016/05/04
- [Qemu-block] [PATCH v6 15/20] m25p80: Switch to byte-based block access, Eric Blake, 2016/05/04