sd: Fix maximum I/O size for BLOCK_PC requests (4f258a46) · Commits · 戴 / test

Commit ("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 <martin.petersen@oracle.com> Reported-by:

Brian King <brking@linux.vnet.ibm.com> Tested-by:

Brian King <brking@linux.vnet.ibm.com> Cc: stable@vger.kernel.org # 3.17+ Signed-off-by:

James Bottomley <JBottomley@Odin.com>

block/blk-settings.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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

drivers/scsi/sd.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -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);

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