On 07/16/2015 03:13 AM, Martin K. Petersen wrote:
> Commit bcdb247c6b6a ("sd: Limit transfer length") clamped the maximum
> size of an I/O request to the MAXIMUM TRANSFER LENGTH field in the BLOCK
> LIMITS VPD. This had the unfortunate effect of also limiting the maximum
> size of non-filesystem requests sent to the device through sg/bsg.
>
> Avoid using blk_queue_max_hw_sectors() and set the max_sectors queue
> limit directly.
>
> Also update the comment in blk_limits_max_hw_sectors() to clarify that
> max_hw_sectors defines the limit for the I/O controller only.
>
> Signed-off-by: Martin K. Petersen <[email protected]>
> Reported-by: Brian King <[email protected]>
> Tested-by: Brian King <[email protected]>
> Cc: <[email protected]> # 3.17+
> ---
> block/blk-settings.c | 4 ++--
> drivers/scsi/sd.c | 6 +++---
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index 12600bfffca9..e0057d035200 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -241,8 +241,8 @@ EXPORT_SYMBOL(blk_queue_bounce_limit);
> * Description:
> * Enables a low level driver to set a hard upper limit,
> * max_hw_sectors, on the size of requests. max_hw_sectors is set by
> - * the device driver based upon the combined capabilities of I/O
> - * controller and storage device.
> + * the device driver based upon the capabilities of the I/O
> + * controller.
> *
> * max_sectors is a soft limit imposed by the block layer for
> * filesystem type requests. This value can be overridden on a
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 3b2fcb4fada0..a20da8c25b4f 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -2770,9 +2770,9 @@ static int sd_revalidate_disk(struct gendisk *disk)
> max_xfer = sdkp->max_xfer_blocks;
> max_xfer <<= ilog2(sdp->sector_size) - 9;
>
> - max_xfer = min_not_zero(queue_max_hw_sectors(sdkp->disk->queue),
> - max_xfer);
> - blk_queue_max_hw_sectors(sdkp->disk->queue, max_xfer);
> + sdkp->disk->queue->limits.max_sectors =
> + min_not_zero(queue_max_hw_sectors(sdkp->disk->queue), max_xfer);
> +
> set_capacity(disk, sdkp->capacity);
> sd_config_write_same(sdkp);
> kfree(buffer);
>
Reviewed-by: Hannes Reinecke <[email protected]>
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
[email protected] +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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