[SCSI] sd: add fix for devices with last sector access problems

This patch adds a new scsi_device flag (last_sector_bug) for devices
which contain a bug where the device crashes when the last sector is
read in a larger then 1 sector read.

This is for example the case with sdcards in the HP PSC1350 printer
cardreader and in the HP PSC1610 printer cardreader.

Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 10 insertions, 0 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 212f6bcfd457..24eba3118b5a 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -395,6 +395,15 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq)
                 goto out;
         }
 
+        /*
+         * Some devices (some sdcards for one) don't like it if the
+         * last sector gets read in a larger then 1 sector read.
+         */
+        if (unlikely(sdp->last_sector_bug &&
+            rq->nr_sectors > sdp->sector_size / 512 &&
+            block + this_count == get_capacity(disk)))
+                this_count -= sdp->sector_size / 512;
+
         SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt, "block=%llu\n",
                                         (unsigned long long)block));
 
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index e0c645ac5014..3c8f898b160e 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -139,6 +139,7 @@ struct scsi_device {
         unsigned fix_capacity:1;        /* READ_CAPACITY is too high by 1 */
         unsigned guess_capacity:1;      /* READ_CAPACITY might be too high by 1 */
         unsigned retry_hwerror:1;       /* Retry HARDWARE_ERROR */
+        unsigned last_sector_bug:1;     /* Always read last sector in a 1 sector read */
 
         DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
         struct list_head event_list;    /* asserted events */