On Fri, 2008-02-01 at 12:03 -0500, Tony Battersby wrote:
> This patch fixes a problem with some out-of-spec SCSI disks that report
> hardware or medium errors incorrectly. Without the patch, the kernel
> may silently ignore a failed write command or return corrupted data on a
> failed read command.
>
> Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
> ---
>
> This is a simplified version of the original patch that fixes just the
> problem at hand, without trying to handle other theoretical out-of-spec
> cases.
Actually, to restore the original check, this is what we want, isn't it?
Ok, so I also made the sector division logic futureproof for the day we
have > 4096 sector devices ...
James
---
>From 5ae2e4a8ff095aab5997f17068d3e4212c33f039 Mon Sep 17 00:00:00 2001
From: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
Date: Fri, 1 Feb 2008 12:03:27 -0500
Subject: [SCSI] sd: make error handling more robust
This patch fixes a problem with some out-of-spec SCSI disks that report
hardware or medium errors incorrectly. Without the patch, the kernel
may silently ignore a failed write command or return corrupted data on a
failed read command.
Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
Cc: Stable Tree <stable@xxxxxxxxxx>
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/scsi/sd.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
Index: BUILD-2.6/drivers/scsi/sd.c
===================================================================
--- BUILD-2.6.orig/drivers/scsi/sd.c 2008-02-02 15:43:20.000000000 -0600
+++ BUILD-2.6/drivers/scsi/sd.c 2008-02-02 16:01:24.000000000 -0600
@@ -929,6 +929,7 @@
unsigned int xfer_size = scsi_bufflen(SCpnt);
unsigned int good_bytes = result ? 0 : xfer_size;
u64 start_lba = SCpnt->request->sector;
+ u64 end_lba = SCpnt->request->sector + (xfer_size / 512);
u64 bad_lba;
struct scsi_sense_hdr sshdr;
int sense_valid = 0;
@@ -967,26 +968,23 @@
goto out;
if (xfer_size <= SCpnt->device->sector_size)
goto out;
- switch (SCpnt->device->sector_size) {
- case 256:
+ if (SCpnt->device->sector_size < 512) {
+ /* only legitimate sector_size here is 256 */
start_lba <<= 1;
- break;
- case 512:
- break;
- case 1024:
- start_lba >>= 1;
- break;
- case 2048:
- start_lba >>= 2;
- break;
- case 4096:
- start_lba >>= 3;
- break;
- default:
- /* Print something here with limiting frequency. */
- goto out;
- break;
+ end_lba <<= 1;
+ } else {
+ /* be careful ... don't want any overflows */
+ u64 factor = SCpnt->device->sector_size / 512;
+ do_div(start_lba, factor);
+ do_div(end_lba, factor);
}
+
+ if (bad_lba < start_lba || bad_lba >= end_lba)
+ /* the bad lba was reported incorrectly, we have
+ * no idea where the error is
+ */
+ goto out;
+
/* This computation should always be done in terms of
* the resolution of the device's medium.
*/
-
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