[PATCH] scsi: sd: Optimal I/O size should be a multiple of reported granularity

["Martin K. Petersen" <martin.petersen@xxxxxxxxxx>]

Commit a83da8a4509d ("scsi: sd: Optimal I/O size should be a multiple of
physical block size") validated the reported optimal I/O size against the
physical block size to overcome problems with devices reporting nonsensical
transfer sizes.

However, some devices claim conformity to older SCSI versions that predate
the physical block size being reported. Other devices do not report a
physical block size at all. We need to be able to validate the optimal I/O
size on those devices as well.

Many devices report an OPTIMAL TRANSFER LENGTH GRANULARITY in the same VPD
page as the OPTIMAL TRANSFER LENGTH. Use this value to validate the optimal
I/O size. Also check that the reported granularity is a multiple of the
physical block size, if supported.

Link: https://lore.kernel.org/r/33fb522e-4f61-1b76-914f-c9e6a3553c9b@xxxxxxxxx
Reported-by: Bernhard Sulzer <micraft.b@xxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
---
 drivers/scsi/sd.c | 43 +++++++++++++++++++++++++++++++++++++++----
 drivers/scsi/sd.h |  1 +
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 8ca9299ffd36..e41f8eb00787 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2858,7 +2858,6 @@ static void sd_read_app_tag_own(struct scsi_disk *sdkp, unsigned char *buffer)
  */
 static void sd_read_block_limits(struct scsi_disk *sdkp)
 {
-	unsigned int sector_sz = sdkp->device->sector_size;
 	const int vpd_len = 64;
 	unsigned char *buffer = kmalloc(vpd_len, GFP_KERNEL);
 
@@ -2867,9 +2866,7 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
 	    scsi_get_vpd_page(sdkp->device, 0xb0, buffer, vpd_len))
 		goto out;
 
-	blk_queue_io_min(sdkp->disk->queue,
-			 get_unaligned_be16(&buffer[6]) * sector_sz);
-
+	sdkp->min_xfer_blocks = get_unaligned_be16(&buffer[6]);
 	sdkp->max_xfer_blocks = get_unaligned_be32(&buffer[8]);
 	sdkp->opt_xfer_blocks = get_unaligned_be32(&buffer[12]);
 
@@ -3036,6 +3033,29 @@ static void sd_read_security(struct scsi_disk *sdkp, unsigned char *buffer)
 		sdkp->security = 1;
 }
 
+static bool sd_validate_min_xfer_size(struct scsi_disk *sdkp)
+{
+	struct scsi_device *sdp = sdkp->device;
+	unsigned int min_xfer_bytes =
+		logical_to_bytes(sdp, sdkp->min_xfer_blocks);
+
+	if (sdkp->min_xfer_blocks == 0)
+		return false;
+
+	if (min_xfer_bytes & (sdkp->physical_block_size - 1)) {
+		sd_first_printk(KERN_WARNING, sdkp,
+				"Preferred minimum I/O size %u bytes not a " \
+				"multiple of physical block size (%u bytes)\n",
+				min_xfer_bytes, sdkp->physical_block_size);
+		sdkp->min_xfer_blocks = 0;
+		return false;
+	}
+
+	sd_first_printk(KERN_INFO, sdkp, "Preferred minimum I/O size %u bytes\n",
+			min_xfer_bytes);
+	return true;
+}
+
 /*
  * Determine the device's preferred I/O size for reads and writes
  * unless the reported value is unreasonably small, large, not a
@@ -3047,6 +3067,8 @@ static bool sd_validate_opt_xfer_size(struct scsi_disk *sdkp,
 	struct scsi_device *sdp = sdkp->device;
 	unsigned int opt_xfer_bytes =
 		logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
+	unsigned int min_xfer_bytes =
+		logical_to_bytes(sdp, sdkp->min_xfer_blocks);
 
 	if (sdkp->opt_xfer_blocks == 0)
 		return false;
@@ -3083,6 +3105,15 @@ static bool sd_validate_opt_xfer_size(struct scsi_disk *sdkp,
 		return false;
 	}
 
+	if (min_xfer_bytes && opt_xfer_bytes & (min_xfer_bytes - 1)) {
+		sd_first_printk(KERN_WARNING, sdkp,
+				"Optimal transfer size %u bytes not a " \
+				"multiple of preferred minimum block " \
+				"size (%u bytes)\n",
+				opt_xfer_bytes, min_xfer_bytes);
+		return false;
+	}
+
 	sd_first_printk(KERN_INFO, sdkp, "Optimal transfer size %u bytes\n",
 			opt_xfer_bytes);
 	return true;
@@ -3166,6 +3197,10 @@ 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);
 
+	if (sd_validate_min_xfer_size(sdkp))
+		blk_queue_io_min(sdkp->disk->queue,
+				 logical_to_bytes(sdp, sdkp->min_xfer_blocks));
+
 	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);
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 50fff0bf8c8e..7efdcb103c2a 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -82,6 +82,7 @@ struct scsi_disk {
 #endif
 	atomic_t	openers;
 	sector_t	capacity;	/* size in logical blocks */
+	u32		min_xfer_blocks;
 	u32		max_xfer_blocks;
 	u32		opt_xfer_blocks;
 	u32		max_ws_blocks;
-- 
2.24.1