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Date: Wed, 19 Dec 2012 14:58:01 -0500
From: Mike Snitzer <snitzer@redhat.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Joseph Salisbury <joseph.salisbury@canonical.com>,
        Kernel Team <kernel-team@lists.ubuntu.com>,
        linux-kernel@vger.kernel.org, jgarzik@redhat.com,
        JBottomley@Parallels.com, Milan Broz <mbroz@redhat.com>
Subject: Re: [v3.7 Regression]  [SCSI] sd: Implement support for WRITE SAME
Message-ID: <20121219195801.GA14456@redhat.com>
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On Wed, Dec 19 2012 at 11:58am -0500,
Martin K. Petersen <martin.petersen@oracle.com> wrote:

> >>>>> "Joseph" == Joseph Salisbury <joseph.salisbury@canonical.com> writes:
> 
> Joseph> I captured the netconsole output from boot until I reproduced
> Joseph> the bug. The RIP points to kcryptd_crypt_write_io_submit() in
> Joseph> ~/drivers/md/dm-crypt.c.  The output can be seen at:
> 
> I'm thinking that dm-crypt should probably set max_write_same_sectors to
> 0. It doesn't really make much sense for a crypto driver to pass that
> command through.
> 
> Mike, do you want to look into this?

Milan (cc'd) is more well-versed with dm-crypt.  Though we likely need
to audit DM relative to WRITE SAME too (will do once I understand what
added safety/constraints are needed).

But do we know mount to somwhow be issuing WRITE SAME requests?  Martin,
why is it you weren't able to reproduce (I haven't attempted yet)?