[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-block] [PATCH v7 06/19] scsi-disk: Switch to byte-based aio bl
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [PATCH v7 06/19] scsi-disk: Switch to byte-based aio block access |
Date: |
Tue, 10 May 2016 10:55:44 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 06.05.2016 um 18:26 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.
>
> As part of the cleanup, scsi_init_iovec() no longer needs to return
> a value, and reword a comment.
>
> Signed-off-by: Eric Blake <address@hidden>
>
> ---
> v7: remove more unused 'n', fix comment wording
> ---
> hw/scsi/scsi-disk.c | 41 ++++++++++++++++++++---------------------
> 1 file changed, 20 insertions(+), 21 deletions(-)
>
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index 1335392..d6bb9ad 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -108,7 +108,7 @@ static void scsi_check_condition(SCSIDiskReq *r,
> SCSISense sense)
> scsi_req_complete(&r->req, CHECK_CONDITION);
> }
>
> -static uint32_t scsi_init_iovec(SCSIDiskReq *r, size_t size)
> +static void scsi_init_iovec(SCSIDiskReq *r, size_t size)
> {
> SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
>
> @@ -118,7 +118,6 @@ static uint32_t scsi_init_iovec(SCSIDiskReq *r, size_t
> size)
> }
> r->iov.iov_len = MIN(r->sector_count * 512, r->buflen);
> qemu_iovec_init_external(&r->qiov, &r->iov, 1);
> - return r->qiov.size / 512;
The return value was MIN(r->sector_count, SCSI_DMA_BUF_SIZE / 512).
> }
>
> static void scsi_disk_save_request(QEMUFile *f, SCSIRequest *req)
> @@ -316,7 +315,6 @@ done:
> static void scsi_do_read(SCSIDiskReq *r, int ret)
> {
> SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
> - uint32_t n;
>
> assert (r->req.aiocb == NULL);
>
> @@ -340,11 +338,12 @@ static void scsi_do_read(SCSIDiskReq *r, int ret)
> r->req.aiocb = dma_blk_read(s->qdev.conf.blk, r->req.sg, r->sector,
> scsi_dma_complete, r);
> } else {
> - n = scsi_init_iovec(r, SCSI_DMA_BUF_SIZE);
> + 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);
> - r->req.aiocb = blk_aio_readv(s->qdev.conf.blk, r->sector, &r->qiov,
> n,
> - scsi_read_complete, r);
> + SCSI_DMA_BUF_SIZE, BLOCK_ACCT_READ);
But here you use SCSI_DMA_BUF_SIZE without considering r->sector_count.
Is this correct or are requests that are smaller than SCSI_DMA_BUF_SIZE
now accounted for more data than they actually read?
Would r->qiov.size be more obviously correct? You did that for writes.
> + r->req.aiocb = blk_aio_preadv(s->qdev.conf.blk,
> + r->sector << BDRV_SECTOR_BITS,
> &r->qiov,
> + 0, scsi_read_complete, r);
> }
>
> done:
Kevin
- [Qemu-block] [PATCH v7 00/19] block: kill sector-based blk_write/read, Eric Blake, 2016/05/06
- [Qemu-block] [PATCH v7 07/19] virtio: Switch to byte-based aio block access, Eric Blake, 2016/05/06
- [Qemu-block] [PATCH v7 09/19] fdc: Switch to byte-based block access, Eric Blake, 2016/05/06
- [Qemu-block] [PATCH v7 11/19] onenand: Switch to byte-based block access, Eric Blake, 2016/05/06
- [Qemu-block] [PATCH v7 15/19] atapi: Switch to byte-based block access, Eric Blake, 2016/05/06
- [Qemu-block] [PATCH v7 16/19] nbd: Switch to byte-based block access, Eric Blake, 2016/05/06