[dm-devel] failover does not work with rdac device handler
Moger, Babu
Babu.Moger at lsi.com
Thu Oct 23 17:31:54 UTC 2008
Thanks for the updates..
Babu Moger
-----Original Message-----
From: Chandra Seetharaman [mailto:sekharan at us.ibm.com]
Sent: Thursday, October 23, 2008 12:15 PM
To: Moger, Babu
Cc: device-mapper development; linux-scsi at vger.kernel.org
Subject: RE: [dm-devel] failover does not work with rdac device handler
Hi Babu,
There is an another issue w.r.t non-listed devices (like you tested).
The issue is that when the device disappears and reappear, the dh_state
file is not created for them. I wanted to send the patch for that also
together with this one. That is the reason for delay.
chandra
On Thu, 2008-10-23 at 08:12 -0600, Moger, Babu wrote:
> Hello Chandra,
> I have not seen this patch being submitted to mainstream kernel. When are you planning to submit this patch? Should I open a bugzilla for tracking purposes?
>
> Thanks
> Babu Moger
> -----Original Message-----
> From: Chandra Seetharaman [mailto:sekharan at us.ibm.com]
> Sent: Tuesday, October 07, 2008 2:19 PM
> To: Moger, Babu
> Cc: device-mapper development; linux-scsi at vger.kernel.org
> Subject: RE: [dm-devel] failover does not work with rdac device handler
>
>
> Sorry, I sent an imcomplete patch. Here is the correct one.
>
> BTW, The panic you saw is caused by the line (one of the lines you
> added):
>
> dev = container_of(&scsi_dh_data, struct scsi_device, scsi_dh_data);
>
> in scsi_dh_release(). We cannot use pointer in a structure to get the
> parent structure.
>
> chandra
>
> Keep a reference count of attaches, so that same number of detaches are allowed.
> -----------
>
> Signed-off-by: Chandra Seetharaman <sekharan at us.ibm.com>
> ---
> Index: linux-2.6.27-rc8-git5/drivers/scsi/device_handler/scsi_dh.c
> ===================================================================
> --- linux-2.6.27-rc8-git5.orig/drivers/scsi/device_handler/scsi_dh.c
> +++ linux-2.6.27-rc8-git5/drivers/scsi/device_handler/scsi_dh.c
> @@ -153,12 +153,28 @@ static int scsi_dh_handler_attach(struct
> if (sdev->scsi_dh_data) {
> if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
> err = -EBUSY;
> - } else if (scsi_dh->attach)
> + else
> + kref_get(&sdev->scsi_dh_data->kref);
> + } else if (scsi_dh->attach) {
> err = scsi_dh->attach(sdev);
> + if (!err) {
> + kref_init(&sdev->scsi_dh_data->kref);
> + sdev->scsi_dh_data->sdev = sdev;
> + }
> + }
>
> return err;
> }
>
> +static void scsi_dh_release(struct kref *kref)
> +{
> + struct scsi_dh_data *scsi_dh_data;
> + scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
> +
> + if (scsi_dh_data->scsi_dh && scsi_dh_data->scsi_dh->detach)
> + scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
> +}
> +
> /*
> * scsi_dh_handler_detach - Detach a device handler from a device
> * @sdev - SCSI device the device handler should be detached from
> @@ -176,11 +192,7 @@ static void scsi_dh_handler_detach(struc
> if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
> return;
>
> - if (!scsi_dh)
> - scsi_dh = sdev->scsi_dh_data->scsi_dh;
> -
> - if (scsi_dh && scsi_dh->detach)
> - scsi_dh->detach(sdev);
> + kref_put(&sdev->scsi_dh_data->kref, scsi_dh_release);
> }
>
> /*
> Index: linux-2.6.27-rc8-git5/include/scsi/scsi_device.h
> ===================================================================
> --- linux-2.6.27-rc8-git5.orig/include/scsi/scsi_device.h
> +++ linux-2.6.27-rc8-git5/include/scsi/scsi_device.h
> @@ -6,6 +6,7 @@
> #include <linux/spinlock.h>
> #include <linux/workqueue.h>
> #include <linux/blkdev.h>
> +#include <linux/kref.h>
> #include <scsi/scsi.h>
> #include <asm/atomic.h>
>
> @@ -191,6 +192,8 @@ struct scsi_device_handler {
>
> struct scsi_dh_data {
> struct scsi_device_handler *scsi_dh;
> + struct kref kref;
> + struct scsi_device *sdev; /* back reference */
> char buf[0];
> };
>
>
>
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