src/patches/suse-2.6.27.25/patches.fixes/dm-mpath-reattach-dh

   1 From: Hannes Reinecke <hare@suse.de>
   2 Subject: Reattach device handler for multipath devices
   3 References: bnc#435688
   4
   5 The multipath daemon might have specified a different device_handler
   6 than the one a device is attached to by default.
   7 So we should try to re-attach with the user-specified device_handler
   8 and only return an error if that fails.
   9 And we should _not_ detach existing hardware handlers. This will
  10 set the path to failed during failover.
  11
  12 Signed-off-by: Hannes Reinecke <hare@suse.de
  13
  14 ---
  15  drivers/md/dm-mpath.c                 |   16 ++++++++++++----
  16  drivers/scsi/device_handler/scsi_dh.c |   10 +++-------
  17  2 files changed, 15 insertions(+), 11 deletions(-)
  18
  19 --- a/drivers/md/dm-mpath.c
  20 +++ b/drivers/md/dm-mpath.c
  21 @@ -163,8 +163,6 @@ static void free_pgpaths(struct list_hea
  22
  23         list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
  24                 list_del(&pgpath->list);
  25 -               if (m->hw_handler_name)
  26 -                       scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
  27                 dm_put_device(ti, pgpath->path.dev);
  28                 spin_lock_irqsave(&m->lock, flags);
  29                 if (m->pgpath_to_activate == pgpath)
  30 @@ -593,9 +591,19 @@ static struct pgpath *parse_path(struct
  31         }
  32
  33         if (m->hw_handler_name) {
  34 -               r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev),
  35 -                                  m->hw_handler_name);
  36 +               struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
  37 +
  38 +               r = scsi_dh_attach(q, m->hw_handler_name);
  39 +               if (r == -EBUSY) {
  40 +                       /*
  41 +                        * Already attached to different hw_handler,
  42 +                        * try to reattach with correct one.
  43 +                        */
  44 +                       scsi_dh_detach(q);
  45 +                       r = scsi_dh_attach(q, m->hw_handler_name);
  46 +               }
  47                 if (r < 0) {
  48 +                       ti->error = "error attaching hardware handler";
  49                         dm_put_device(ti, p->path.dev);
  50                         goto bad;
  51                 }
  52 --- a/drivers/scsi/device_handler/scsi_dh.c
  53 +++ b/drivers/scsi/device_handler/scsi_dh.c
  54 @@ -498,7 +498,6 @@ void scsi_dh_detach(struct request_queue
  55  {
  56         unsigned long flags;
  57         struct scsi_device *sdev;
  58 -       struct scsi_device_handler *scsi_dh = NULL;
  59
  60         spin_lock_irqsave(q->queue_lock, flags);
  61         sdev = scsi_device_from_queue(q);
  62 @@ -509,12 +508,9 @@ void scsi_dh_detach(struct request_queue
  63         if (!sdev)
  64                 return;
  65
  66 -       if (sdev->scsi_dh_data) {
  67 -               /* if sdev is not on internal list, detach */
  68 -               scsi_dh = sdev->scsi_dh_data->scsi_dh;
  69 -               if (!device_handler_match(scsi_dh, sdev))
  70 -                       scsi_dh_handler_detach(sdev, scsi_dh);
  71 -       }
  72 +       if (sdev->scsi_dh_data)
  73 +               scsi_dh_handler_detach(sdev, sdev->scsi_dh_data->scsi_dh);
  74 +
  75         put_device(&sdev->sdev_gendev);
  76  }
  77  EXPORT_SYMBOL_GPL(scsi_dh_detach);