On Wed, 01/20 11:01, Martin K. Petersen wrote:
> Commit ca369d51b3e1 ("block/sd: Fix device-imposed transfer length
> limits") accidentally switched optimal I/O size reporting from bytes to
> block layer sectors.
>
> Signed-off-by: Martin K. Petersen <[email protected]>
> Reported-by: Christian Borntraeger <[email protected]>
> ---
> drivers/scsi/sd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 4e08d1cd704d..ec163d08f6c3 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -2893,7 +2893,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
> sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
> sdkp->opt_xfer_blocks * sdp->sector_size >= PAGE_CACHE_SIZE)
> rw_max = q->limits.io_opt =
> - logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
> + sdkp->opt_xfer_blocks * sdp->sector_size;
Hi Martin,
This looks wrong to me, maybe I'm missing the obvious? Here
sdkp->opt_xfer_blocks is in block size unit, and rw_max is in byte unit.
Following is:
else
rw_max = BLK_DEF_MAX_SECTORS;
Which seems in sector unit, and is already making above change suspicious, and
further down:
/* Combine with controller limits */
q->limits.max_sectors = min(rw_max, queue_max_hw_sectors(q));
looks like a unit mismatch to me. IIUC q->limits.max_sectors _is_ in sector
unit, similar to queue_max_hw_sectors().
Is the error reported by Christian fixed just because we are setting an
incorrect high max?
(I noticed this when I see I/O error because a virtio-scsi guest starts to
issue large reads that are rejected by host device.)
Fam
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