src/patches/suse-2.6.27.25/patches.suse/dm-mpath-requeue-for-stopped-queue

   1 From: Hannes Reinecke <hare@suse.de>
   2 Subject: Handle I/O on stopped queues correctly
   3 References: bnc#458393
   4
   5 The current multipath infrastructure has several issues when I/O is
   6 submitted during a table reload.
   7 The make_request_fn must not fail if no table is present, as I/O
   8 will be queued properly in the request queue. But on the other hand
   9 we should not submit queued I/Os if the queue of the underlying
  10 device is stopped; that queue is undergoing reconfiguration
  11 time and may be in all sort of states.
  12
  13 And while we're at it, we should detach any hardware handler
  14 if the multipath table doesn't specify one.
  15
  16 Signed-off-by: Hannes Reinecke <hare@suse.de>
  17
  18 Index: linux-2.6.27/drivers/md/dm-mpath.c
  19 ===================================================================
  20 --- linux-2.6.27.orig/drivers/md/dm-mpath.c
  21 +++ linux-2.6.27/drivers/md/dm-mpath.c
  22 @@ -159,9 +159,7 @@ static struct priority_group *alloc_prio
  23
  24  static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
  25  {
  26 -       unsigned long flags;
  27         struct pgpath *pgpath, *tmp;
  28 -       struct multipath *m = ti->private;
  29
  30         list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
  31                 list_del(&pgpath->list);
  32 @@ -436,8 +434,8 @@ static void process_queued_ios(struct wo
  33  {
  34         struct multipath *m =
  35                 container_of(work, struct multipath, process_queued_ios);
  36 -       struct pgpath *pgpath = NULL, *tmp;
  37 -       unsigned must_queue = 1;
  38 +       struct pgpath *pgpath = NULL, *tmp;
  39 +       unsigned must_queue = 1;
  40         unsigned long flags;
  41
  42         spin_lock_irqsave(&m->lock, flags);
  43 @@ -450,6 +448,12 @@ static void process_queued_ios(struct wo
  44
  45         pgpath = m->current_pgpath;
  46
  47 +       if (pgpath) {
  48 +               struct block_device *bdev = pgpath->path.dev->bdev;
  49 +               if (unlikely(blk_queue_stopped(bdev_get_queue(bdev))))
  50 +                       goto out;
  51 +       }
  52 +
  53         if ((pgpath && !m->queue_io) ||
  54             (!pgpath && !m->queue_if_no_path))
  55                 must_queue = 0;
  56 @@ -619,22 +623,24 @@ static struct pgpath *parse_path(struct
  57                 memcpy(p->path.pdev, p->path.dev->name, 16);
  58         }
  59
  60 -       if (m->hw_handler_name && p->path.dev) {
  61 +       if (p->path.dev) {
  62                 struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
  63
  64 -               r = scsi_dh_attach(q, m->hw_handler_name);
  65 -               if (r == -EBUSY) {
  66 -                       /*
  67 -                        * Already attached to different hw_handler,
  68 -                        * try to reattach with correct one.
  69 -                        */
  70 -                       scsi_dh_detach(q);
  71 +               if (m->hw_handler_name) {
  72                         r = scsi_dh_attach(q, m->hw_handler_name);
  73 -               }
  74 -               if (r < 0) {
  75 -                       ti->error = "error attaching hardware handler";
  76 -                       dm_put_device(ti, p->path.dev);
  77 -                       goto bad;
  78 +                       if (r == -EBUSY) {
  79 +                               /*
  80 +                                * Already attached to different hw_handler,
  81 +                                * try to reattach with correct one.
  82 +                                */
  83 +                               scsi_dh_detach(q);
  84 +                               r = scsi_dh_attach(q, m->hw_handler_name);
  85 +                       }
  86 +                       if (r < 0) {
  87 +                               ti->error = "error attaching hardware handler";
  88 +                               dm_put_device(ti, p->path.dev);
  89 +                               goto bad;
  90 +                       }
  91                 }
  92         }
  93
  94 @@ -644,6 +653,11 @@ static struct pgpath *parse_path(struct
  95                 goto bad;
  96         }
  97
  98 +       if (!p->is_active) {
  99 +               ps->type->fail_path(ps, &p->path);
 100 +               p->fail_count++;
 101 +               m->nr_valid_paths--;
 102 +       }
 103         return p;
 104
 105   bad:
 106 Index: linux-2.6.27/drivers/md/dm.c
 107 ===================================================================
 108 --- linux-2.6.27.orig/drivers/md/dm.c
 109 +++ linux-2.6.27/drivers/md/dm.c
 110 @@ -1304,7 +1304,11 @@ static int dm_make_request(struct reques
 111                 return 0;
 112         }
 113
 114 -       if (unlikely(!md->map)) {
 115 +       /*
 116 +        * Submitting to a stopped queue with no map is okay;
 117 +        * might happen during reconfiguration.
 118 +        */
 119 +       if (unlikely(!md->map) && !blk_queue_stopped(q)) {
 120                 bio_endio(bio, -EIO);
 121                 return 0;
 122         }