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Commit a83da8a4 authored by Martin K. Petersen's avatar Martin K. Petersen
Browse files

scsi: sd: Optimal I/O size should be a multiple of physical block size 

It was reported that some devices report an OPTIMAL TRANSFER LENGTH of
0xFFFF blocks. That looks bogus, especially for a device with a
4096-byte physical block size.

Ignore OPTIMAL TRANSFER LENGTH if it is not a multiple of the device's
reported physical block size.

To make the sanity checking conditionals more readable--and to
facilitate printing warnings--relocate the checking to a helper
function. No functional change aside from the printks.

Cc: <stable@vger.kernel.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759


Reported-by: default avatarChristoph Anton Mitterer <calestyo@scientia.net>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent d1420f2c

drivers/scsi/sd.c

+50 −9
Original line number Diff line number Diff line
@@ -3061,6 +3061,55 @@ static void sd_read_security(struct scsi_disk *sdkp, unsigned char *buffer) 
		sdkp->security = 1;

}



/*

 * Determine the device's preferred I/O size for reads and writes

 * unless the reported value is unreasonably small, large, not a

 * multiple of the physical block size, or simply garbage.

 */

static bool sd_validate_opt_xfer_size(struct scsi_disk *sdkp,

				      unsigned int dev_max)

{

	struct scsi_device *sdp = sdkp->device;

	unsigned int opt_xfer_bytes =

		logical_to_bytes(sdp, sdkp->opt_xfer_blocks);



	if (sdkp->opt_xfer_blocks > dev_max) {

		sd_first_printk(KERN_WARNING, sdkp,

				"Optimal transfer size %u logical blocks " \

				"> dev_max (%u logical blocks)\n",

				sdkp->opt_xfer_blocks, dev_max);

		return false;

	}



	if (sdkp->opt_xfer_blocks > SD_DEF_XFER_BLOCKS) {

		sd_first_printk(KERN_WARNING, sdkp,

				"Optimal transfer size %u logical blocks " \

				"> sd driver limit (%u logical blocks)\n",

				sdkp->opt_xfer_blocks, SD_DEF_XFER_BLOCKS);

		return false;

	}



	if (opt_xfer_bytes < PAGE_SIZE) {

		sd_first_printk(KERN_WARNING, sdkp,

				"Optimal transfer size %u bytes < " \

				"PAGE_SIZE (%u bytes)\n",

				opt_xfer_bytes, (unsigned int)PAGE_SIZE);

		return false;

	}



	if (opt_xfer_bytes & (sdkp->physical_block_size - 1)) {

		sd_first_printk(KERN_WARNING, sdkp,

				"Optimal transfer size %u bytes not a " \

				"multiple of physical block size (%u bytes)\n",

				opt_xfer_bytes, sdkp->physical_block_size);

		return false;

	}



	sd_first_printk(KERN_INFO, sdkp, "Optimal transfer size %u bytes\n",

			opt_xfer_bytes);

	return true;

}



/**

 *	sd_revalidate_disk - called the first time a new disk is seen,

 *	performs disk spin up, read_capacity, etc.
@@ -3130,15 +3179,7 @@ static int sd_revalidate_disk(struct gendisk *disk) 
	dev_max = min_not_zero(dev_max, sdkp->max_xfer_blocks);

	q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);



	/*

	 * Determine the device's preferred I/O size for reads and writes

	 * unless the reported value is unreasonably small, large, or

	 * garbage.

	 */

	if (sdkp->opt_xfer_blocks &&

	    sdkp->opt_xfer_blocks <= dev_max &&

	    sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&

	    logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {

	if (sd_validate_opt_xfer_size(sdkp, dev_max)) {

		q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);

		rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);

	} else