On Wed, 2015-06-03 at 11:29 +0200, Jiri Slaby wrote:
> On 06/03/2015, 08:35 AM, gre...@linuxfoundation.org wrote:
> > From 74856fbf441929918c49ff262ace9835048e4e6a Mon Sep 17 00:00:00 2001
> > From: Mark Hounschell <dma...@cfl.rr.com>
> > Date: Wed, 13 May 2015 10:49:09 +0200
> > Subject: sd: Disable support for 256 byte/sector disks
> >
> > From: Mark Hounschell <dma...@cfl.rr.com>
> >
> > commit 74856fbf441929918c49ff262ace9835048e4e6a upstream.
> >
> > 256 bytes per sector support has been broken since 2.6.X,
> > and no-one stepped up to fix this.
> > So disable support for it.
> >
> > Signed-off-by: Mark Hounschell <dma...@cfl.rr.com>
> > Signed-off-by: Hannes Reinecke <h...@suse.de>
> > Signed-off-by: James Bottomley <jbottom...@odin.com>
> > Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> >
> > ---
> > drivers/scsi/sd.c | 19 +++++--------------
> > 1 file changed, 5 insertions(+), 14 deletions(-)
> >
> > --- a/drivers/scsi/sd.c
> > +++ b/drivers/scsi/sd.c
> > @@ -1624,6 +1624,7 @@ static unsigned int sd_completed_bytes(s
> > {
> > u64 start_lba = blk_rq_pos(scmd->request);
> > u64 end_lba = blk_rq_pos(scmd->request) + (scsi_bufflen(scmd) / 512);
> > + u64 factor = scmd->device->sector_size / 512;
> > u64 bad_lba;
> > int info_valid;
> > /*
> > @@ -1645,16 +1646,9 @@ static unsigned int sd_completed_bytes(s
> > if (scsi_bufflen(scmd) <= scmd->device->sector_size)
> > return 0;
> >
> > - if (scmd->device->sector_size < 512) {
> > - /* only legitimate sector_size here is 256 */
> > - start_lba <<= 1;
> > - end_lba <<= 1;
> > - } else {
> > - /* be careful ... don't want any overflows */
> > - unsigned int factor = scmd->device->sector_size / 512;
> > - do_div(start_lba, factor);
> > - do_div(end_lba, factor);
> > - }
>
> Hmm, you do 'unsigned int' -> 'u64' switch of factor type here. But this
> commit:
> commit ef80d1e18b014af08741cf688e3fdda1fb71363f
> Author: Geert Uytterhoeven <ge...@linux-m68k.org>
> Date: Mon Nov 4 10:21:05 2013 +0100
>
> [SCSI] sd: Do not call do_div() with a 64-bit divisor
>
> did the switch in the opposite direction deliberately.
>
> So why did you do the change, given sector_size is uint?
Primarily because no-one spotted the reversal and none of the static
checkers warns about it.
This is the trivial fix, but we should do something about the checkers.
James
---
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3b2fcb4..3e137dd 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1600,7 +1600,7 @@ static unsigned int sd_completed_bytes(struct scsi_cmnd
*scmd)
{
u64 start_lba = blk_rq_pos(scmd->request);
u64 end_lba = blk_rq_pos(scmd->request) + (scsi_bufflen(scmd) / 512);
- u64 factor = scmd->device->sector_size / 512;
+ unsigned int factor = scmd->device->sector_size / 512;
u64 bad_lba;
int info_valid;
/*
