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dm-mpath, scsi_dh: don't let dm detach device handlers

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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 <[email protected]>
Acked-by: Mike Snitzer <[email protected]>
Acked-by: Hannes Reinecke <[email protected]>
Signed-off-by: James Bottomley <[email protected]>
This commit is contained in:
Christoph Hellwig 2015-08-27 14:16:54 +02:00 • committed by James Bottomley
commit 1bab0de027
4 changed files with 28 additions and 95 deletions
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21
drivers/md/dm-mpath.c
View file

@ -159,12 +159,9 @@ 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);
}
@ -580,6 +577,7 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps
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 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps
}
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 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps
if (r < 0) {
ti->error = "unable to set hardware "
"handler parameters";
scsi_dh_detach(q);
dm_put_device(ti, p->path.dev);
goto bad;
}