From: Mark Lord <lkml@rtr.ca>

When scsi_get_sense_info_fld() fails (returns 0), it does NOT update the
value of first_err_block.  But sd_rw_intr() merrily continues to use that
variable regardless, possibly making incorrect decisions about retries and
the like.

This patch removes the randomness there, by using the first sector of the
request (SCpnt->request->sector) in such cases, instead of first_err_block.

Signed-off-by: Mark Lord <lkml@rtr.ca>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 drivers/scsi/sd.c |    2 ++
 1 files changed, 2 insertions(+)

diff -puN drivers/scsi/sd.c~drivers-scsi-sdc-fix-uninitialized-variable-in-handling-medium-errors drivers/scsi/sd.c
--- 25/drivers/scsi/sd.c~drivers-scsi-sdc-fix-uninitialized-variable-in-handling-medium-errors	Wed Apr 26 15:16:25 2006
+++ 25-akpm/drivers/scsi/sd.c	Wed Apr 26 15:16:25 2006
@@ -959,6 +959,8 @@ static void sd_rw_intr(struct scsi_cmnd 
 			default:
 				break;
 			}
+			if (!info_valid)
+				error_sector = SCpnt->request->sector;
 
 			error_sector &= ~(block_sectors - 1);
 			good_bytes = (error_sector - SCpnt->request->sector) << 9;
_