Bug#604049: linux-image-2.6.32-5-amd64: data corruption with promise stex driver and use of device-mapper layers (lvm/dm-crypt/..)
>-----Original Message-----
>From: Ben Hutchings [mailto:ben@decadent.org.uk]
>Sent: 2010年11月19日 21:34
>To: Ed Lin - PTU; Jens Axboe; dm-devel@redhat.com
>Cc: Markus Schulz; 604049@bugs.debian.org
>Subject: Re: Bug#604049: linux-image-2.6.32-5-amd64: data
>corruption with promise stex driver and use of device-mapper
>layers (lvm/dm-crypt/..)
>
>
>On Fri, 2010-11-19 at 20:26 +0100, Markus Schulz wrote:
>> Package: linux-2.6
>> Version: 2.6.32-27
>> Severity: critical
>> Tags: d-i upstream
>> Justification: causes serious data loss
>>
>> any use of the stex.ko promise hw-raid controller driver with a
>> device-mapper layer produces data corruption (or filesystem
>corruption
>> like you can see in my dmesg).
>[...]
>> i've asked Ed Lin (Maintainer of stex.c from promise) on
>lkml and got the following answer:
>>
>> > We found similar problem during test.
>>
>> > The stex driver sets sg_tablesize as 32 (for st_yel it's
>38) in the probe
>> > entry. It seems that this value was overridden by the
>system if using
>> > dm/lvm, for unknown reason. The driver received requests with more
>> > sg items than registered. Sg item number could be as high
>as 64. This
>> > is completely unexpected. The firmware could not handle such
>> > requests, and error occurred.
>[..]
>
>I have little idea how this stuff is supposed to work, but it
>looks like
>dm_dispatch_request() calls blk_insert_cloned_request() which calls
>blk_rq_check_limits() which checks the request against the maximum
>number of segments initialised from sg_tablesize.
>
>We can perhaps mitigate the data loss by checking the number
>of segments
>again in scsi_dispatch_cmd(), but it won't really solve the problem.
>
I believe the cause of the problem has been found. An explanation
and a possible solution was posted at the linux-scsi mail list
and dm-devel@redhat.com.
The link is http://marc.info/?l=linux-scsi&m=129021716922966&w=2
So far no one responded. Any comment is welcome.
Thanks,
Ed Lin
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