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.

Cc: <[email protected]>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759
Reported-by: Christoph Anton Mitterer <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

---

Before:

NAME ALIGNMENT MIN-IO   OPT-IO PHY-SEC LOG-SEC ROTA SCHED      RQ-SIZE  RA WSAME
sda          0   4096 33553920    4096     512    0 mq-deadline    256 128   32M

After:

NAME ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED       RQ-SIZE   RA WSAME
sda          0   4096      0    4096     512    0 mq-deadline     256 4096   32M
---
 drivers/scsi/sd.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 9421d9877730..2d19eed3dfbc 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3067,7 +3067,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
        struct request_queue *q = sdkp->disk->queue;
        sector_t old_capacity = sdkp->capacity;
        unsigned char *buffer;
-       unsigned int dev_max, rw_max;
+       unsigned int dev_max, rw_max, opt_xfer_bytes;
 
        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
                                      "sd_revalidate_disk\n"));
@@ -3126,13 +3126,16 @@ static int sd_revalidate_disk(struct gendisk *disk)
 
        /*
         * Determine the device's preferred I/O size for reads and writes
-        * unless the reported value is unreasonably small, large, or
-        * garbage.
+        * unless the reported value is unreasonably small, large, not a
+        * multiple of the physical block size, or simply garbage.
         */
+       opt_xfer_bytes = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
+
        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) {
+           opt_xfer_bytes >= PAGE_SIZE &&
+           (opt_xfer_bytes & (sdkp->physical_block_size - 1)) != 0) {
                q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
                rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
        } else
-- 
2.17.1

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