dm-mpath, scsi_dh: don't let dm detach device handlers
While allowing dm-mpath to attach device handlers is a functionality we need
for backwards compatibility reason there is no reason to reference count
them and detach them if dm-mpath stops using the device for some reason.
If the device handler works for the given device it can just stay attached,
and we can take the retain_hw_handler codepath.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Hannes Reinecke <hare@Suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index eff7bdd..a9f58fd 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -159,12 +159,9 @@
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);
}
@@ -580,6 +577,7 @@
q = bdev_get_queue(p->path.dev->bdev);
if (m->retain_attached_hw_handler) {
+retain:
attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
if (attached_handler_name) {
/*
@@ -599,20 +597,14 @@
}
if (m->hw_handler_name) {
- /*
- * Increments scsi_dh reference, even when using an
- * already-attached handler.
- */
r = scsi_dh_attach(q, m->hw_handler_name);
if (r == -EBUSY) {
- /*
- * Already attached to different hw_handler:
- * try to reattach with correct one.
- */
- scsi_dh_detach(q);
- r = scsi_dh_attach(q, m->hw_handler_name);
- }
+ char b[BDEVNAME_SIZE];
+ printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
+ bdevname(p->path.dev->bdev, b));
+ goto retain;
+ }
if (r < 0) {
ti->error = "error attaching hardware handler";
dm_put_device(ti, p->path.dev);
@@ -624,7 +616,6 @@
if (r < 0) {
ti->error = "unable to set hardware "
"handler parameters";
- scsi_dh_detach(q);
dm_put_device(ti, p->path.dev);
goto bad;
}