dm target:s introduce iterate devices fn

Add .iterate_devices to 'struct target_type' to allow a function to be
called for all devices in a DM target.  Implemented it for all targets
except those in dm-snap.c (origin and snapshot).

(The raid1 version number jumps to 1.12 because we originally reserved
1.1 to 1.11 for 'block_on_error' but ended up using 'handle_errors'
instead.)

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: martin.petersen@oracle.com

1 files changed, 22 insertions, 1 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 890c0e8ed13e..f8aeaaa54afe 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1450,12 +1450,32 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
         return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
 }
 
+static int multipath_iterate_devices(struct dm_target *ti,
+                                     iterate_devices_callout_fn fn, void *data)
+{
+        struct multipath *m = ti->private;
+        struct priority_group *pg;
+        struct pgpath *p;
+        int ret = 0;
+
+        list_for_each_entry(pg, &m->priority_groups, list) {
+                list_for_each_entry(p, &pg->pgpaths, list) {
+                        ret = fn(ti, p->path.dev, ti->begin, data);
+                        if (ret)
+                                goto out;
+                }
+        }
+
+out:
+        return ret;
+}
+
 /*-----------------------------------------------------------------
  * Module setup
  *---------------------------------------------------------------*/
 static struct target_type multipath_target = {
         .name = "multipath",
-        .version = {1, 0, 5},
+        .version = {1, 1, 0},
         .module = THIS_MODULE,
         .ctr = multipath_ctr,
         .dtr = multipath_dtr,
@@ -1466,6 +1486,7 @@ static struct target_type multipath_target = {
         .status = multipath_status,
         .message = multipath_message,
         .ioctl  = multipath_ioctl,
+        .iterate_devices = multipath_iterate_devices,
 };
 
 static int __init dm_multipath_init(void)