scsi: sd: Consider max_xfer_blocks if opt_xfer_blocks is unusable

BugLink: http://bugs.launchpad.net/bugs/1687629
commit 6780414519f91c2a84da9baa963a940ac916f803 upstream.

If device reports a small max_xfer_blocks and a zero opt_xfer_blocks, we
end up using BLK_DEF_MAX_SECTORS, which is wrong and r/w of that size
may get error.

[mkp: tweaked to avoid setting rw_max twice and added typecast]

Fixes: ca369d51b3e ("block/sd: Fix device-imposed transfer length limits")
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 78430ef28ea4c36d5c7dbeb6c9683400f035da60..d2877d713b62a22df8090f7c87086918255b7b30 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2888,7 +2888,8 @@ static int sd_revalidate_disk(struct gendisk *disk)
                q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
                rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
        } else
-               rw_max = BLK_DEF_MAX_SECTORS;
+               rw_max = min_not_zero(logical_to_sectors(sdp, dev_max),
+                                     (sector_t)BLK_DEF_MAX_SECTORS);
 
        /* Combine with controller limits */
        q->limits.max_sectors = min(rw_max, queue_max_hw_sectors(q));