src/patches/suse-2.6.27.31/patches.suse/dm-mpath-add-start-io

   1 From: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
   2 Subject: dm-mpath: add a path selector interface
   3 References: FATE#303862,FATE#302108
   4
   5 This patch adds a new hook for dm path selector: start_io.
   6 Target drivers should call this hook before submitting I/O to
   7 the selected path.
   8 Path selectors can use it to start accounting of the I/O.
   9 (e.g. counting the number of in-flight I/Os.)
  10
  11 The code is based on the patch posted by Stefan Bader:
  12 https://www.redhat.com/archives/dm-devel/2005-October/msg00050.html
  13
  14
  15 Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
  16 Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
  17 Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
  18 Signed-off-by: Hannes Reinecke <hare@suse.de>
  19
  20 Index: linux-2.6.27/drivers/md/dm-mpath.c
  21 ===================================================================
  22 --- linux-2.6.27.orig/drivers/md/dm-mpath.c
  23 +++ linux-2.6.27/drivers/md/dm-mpath.c
  24 @@ -359,6 +359,9 @@ static int map_io(struct multipath *m, s
  25
  26         mpio->pgpath = pgpath;
  27
  28 +       if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
  29 +               pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path);
  30 +
  31         spin_unlock_irqrestore(&m->lock, flags);
  32
  33         return r;
  34 Index: linux-2.6.27/drivers/md/dm-path-selector.h
  35 ===================================================================
  36 --- linux-2.6.27.orig/drivers/md/dm-path-selector.h
  37 +++ linux-2.6.27/drivers/md/dm-path-selector.h
  38 @@ -75,6 +75,7 @@ struct path_selector_type {
  39         int (*status) (struct path_selector *ps, struct dm_path *path,
  40                        status_type_t type, char *result, unsigned int maxlen);
  41
  42 +       int (*start_io) (struct path_selector *ps, struct dm_path *path);
  43         int (*end_io) (struct path_selector *ps, struct dm_path *path);
  44  };
  45