Re: [PATCH v2 2/2] sd: check BLK_DEF_MAX_SECTORS against max_dev_sectors

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"Tom" == tom ty89 [off-list ref] writes:

Tom,

Tom> The SCSI disk driver sets max_sectors to BLK_DEF_MAX_SECTORS when
Tom> the device does not report Optimal Transfer Length. However, it
Tom> checks only whether it is smaller than max_hw_sectors, but not
Tom> max_dev_sectors.

It would be pretty unusual for a device that is smart enough to report a
transfer length limit to be constrained to 1 MB and change.

@@ -2875,8 +2875,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	    logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {
 		q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
 		rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
-	} else
+	} else {
 		rw_max = BLK_DEF_MAX_SECTORS;
+		/* Combine with device limits */
+		rw_max = min(rw_max, q->limits.max_dev_sectors);
+	}
 
 	/* Combine with controller limits */
 	q->limits.max_sectors = min(rw_max, queue_max_hw_sectors(q));

If you want to fix this please drop the braces and do:

		rw_max = min(BLK_DEF_MAX_SECTORS, q->limits.max_dev_sectors);

-- 
Martin K. Petersen	Oracle Linux Engineering