linux-kernel - [PATCH 4.9 061/118] scsi: sd: Optimal I/O size should be a multiple of physical block size

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Date:   Fri, 22 Mar 2019 12:15:33 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Christoph Anton Mitterer <calestyo@...entia.net>,
        Christoph Hellwig <hch@....de>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Subject: [PATCH 4.9 061/118] scsi: sd: Optimal I/O size should be a multiple of physical block size

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin K. Petersen <martin.petersen@...cle.com>

commit a83da8a4509d3ebfe03bb7fffce022e4d5d4764f upstream.

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@...r.kernel.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759
Reported-by: Christoph Anton Mitterer <calestyo@...entia.net>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/scsi/sd.c |   59 +++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 50 insertions(+), 9 deletions(-)

--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2834,6 +2834,55 @@ static void sd_read_write_same(struct sc
 		sdkp->ws10 = 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.
@@ -2898,15 +2947,7 @@ static int sd_revalidate_disk(struct gen
 	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