diff options
authorMartin K. Petersen <>2020-03-24 11:16:15 -0400
committerMartin K. Petersen <>2020-03-24 22:53:04 -0400
commitea697a8bf5a4161e59806fab14f6e4a46dc7dcb0 (patch)
parent78c3e5e6cde8193467427ed9e5f90a0d585625a1 (diff)
scsi: sd: Fix optimal I/O size for devices that change reported values
Some USB bridge devices will return a default set of characteristics during initialization. And then, once an attached drive has spun up, substitute the actual parameters reported by the drive. According to the SCSI spec, the device should return a UNIT ATTENTION in case any reported parameters change. But in this case the change is made silently after a small window where default values are reported. 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, this validation did not account for the fact that aforementioned devices will return default values during a brief window during spin-up. The subsequent change in reported characteristics would invalidate the checking that had previously been performed. Unset a previously configured optimal I/O size should the sanity checking fail on subsequent revalidate attempts. Link: Cc: Bryan Gurney <> Cc: <> Reported-by: Bernhard Sulzer <> Tested-by: Bernhard Sulzer <> Signed-off-by: Martin K. Petersen <>
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 8ca9299ffd36..2710a0e5ae6d 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3169,9 +3169,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
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
+ } else {
+ q->limits.io_opt = 0;
rw_max = min_not_zero(logical_to_sectors(sdp, dev_max),
+ }
/* Do not exceed controller limit */
rw_max = min(rw_max, queue_max_hw_sectors(q));