From 5a39cb53a172017ff5ef85e921cee7d2908c77c5 Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Tue, 24 Mar 2020 11:16:15 -0400 Subject: [PATCH] scsi: sd: Fix optimal I/O size for devices that change reported values commit ea697a8bf5a4161e59806fab14f6e4a46dc7dcb0 upstream. 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: https://lore.kernel.org/r/33fb522e-4f61-1b76-914f-c9e6a3553c9b@gmail.com Cc: Bryan Gurney Cc: Reported-by: Bernhard Sulzer Tested-by: Bernhard Sulzer Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 902b649fc8ef..a63ff2887ebf 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -3181,9 +3181,11 @@ 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), (sector_t)BLK_DEF_MAX_SECTORS); + } /* Do not exceed controller limit */ rw_max = min(rw_max, queue_max_hw_sectors(q)); -- 2.11.4.GIT