[SCSI] scsi_dh: attach to hardware handler from dm-mpath

multipath keeps a separate device table which may be
more current than the built-in one.
So we should make sure to always call ->attach whenever
a multipath map with hardware handler is instantiated.
And we should call ->detach on removal, too.

[sekharan: update as per comments from agk]
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index fea966d66f98..71dd65aa31b6 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -147,9 +147,12 @@ static struct priority_group *alloc_priority_group(void)
 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
 {
         struct pgpath *pgpath, *tmp;
+        struct multipath *m = ti->private;
 
         list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
                 list_del(&pgpath->list);
+                if (m->hw_handler_name)
+                        scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
                 dm_put_device(ti, pgpath->path.dev);
                 free_pgpath(pgpath);
         }
@@ -548,6 +551,7 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 {
         int r;
         struct pgpath *p;
+        struct multipath *m = ti->private;
 
         /* we need at least a path arg */
         if (as->argc < 1) {
@@ -566,6 +570,15 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
                 goto bad;
         }
 
+        if (m->hw_handler_name) {
+                r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev),
+                                   m->hw_handler_name);
+                if (r < 0) {
+                        dm_put_device(ti, p->path.dev);
+                        goto bad;
+                }
+        }
+
         r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
         if (r) {
                 dm_put_device(ti, p->path.dev);