Commit 3a9794d3 authored Jan 29, 2015 by Brian King Committed by Christoph Hellwig Feb 02, 2015

sd: Fix max transfer length for 4k disks



The following patch fixes an issue observed with 4k sector disks
where the max_hw_sectors attribute was getting set too large in
sd_revalidate_disk. Since sdkp->max_xfer_blocks is in units
of SCSI logical blocks and queue_max_hw_sectors is in units of
512 byte blocks, on a 4k sector disk, every time we went through
sd_revalidate_disk, we were taking the current value of
queue_max_hw_sectors and increasing it by a factor of 8. Fix
this by only shifting sdkp->max_xfer_blocks.

Cc: stable@vger.kernel.org
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

parent 28072ad5

drivers/scsi/sd.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -2800,9 +2800,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
		*/
		sd_set_flush_flag(sdkp);

		max_xfer = min_not_zero(queue_max_hw_sectors(sdkp->disk->queue),
		sdkp->max_xfer_blocks);
		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);
		set_capacity(disk, sdkp->capacity);
		sd_config_write_same(sdkp);

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