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Message-ID: <1348818332.2411.6.camel@dabdike.int.hansenpartnership.com>
Subject: Re: [PATCH scsi] Short the path length of scsi_cmd_to_driver()
From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>, LKML <linux-kernel@vger.kernel.org>,
        linux-scsi@vger.kernel.org,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Fri, 28 Sep 2012 08:45:32 +0100
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On Thu, 2012-09-27 at 13:43 -0400, Martin K. Petersen wrote:
> >>>>> "Li" == Li Zhong <zhong@linux.vnet.ibm.com> writes:
> 
> > @@ -845,8 +844,11 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
> > 
> > 	scsi_eh_restore_cmnd(scmd, &ses);
> > 
> >-	if (sdrv && sdrv->eh_action)
> >-		rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn);
> >+	if (scmd->request->cmd_type == REQ_TYPE_FS) {
> >+		struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
> >+		if (sdrv->eh_action)
> >+			rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn);
> >+	}
> > 
> > 	return rtn;
> > }
> 
> My only concern is whether our device lifetime rules guarantee that the
> ULD is always attached when we service an error handling command?

Yes, they are.  We can only get REQ_TYPE_FS through a filesystem, which
must be mounted on a block device, which is provided by the ULD.  You
can't unmount with outstanding I/O (which people complain about when it
goes into error handling, I'll admit), so the ULD has to stay bound.

James