md: avoid spinlock problem in blk_throtl_exit
blk_throtl_exit assumes that ->queue_lock still exists,
so make sure that it does.
To do this, we stop redirecting ->queue_lock to conf->device_lock
and leave it pointing where it is initialised - __queue_lock.
As the blk_plug functions check the ->queue_lock is held, we now
take that spin_lock explicitly around the plug functions. We don't
need the locking, just the warning removal.
This is needed for any kernel with the blk_throtl code, which is
which is 2.6.37 and later.
Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 3b607b2..747d061 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -662,7 +662,10 @@
if (conf->pending_bio_list.head) {
struct bio *bio;
bio = bio_list_get(&conf->pending_bio_list);
+ /* Spinlock only taken to quiet a warning */
+ spin_lock(conf->mddev->queue->queue_lock);
blk_remove_plug(conf->mddev->queue);
+ spin_unlock(conf->mddev->queue->queue_lock);
spin_unlock_irq(&conf->device_lock);
/* flush any pending bitmap writes to disk
* before proceeding w/ I/O */
@@ -971,7 +974,7 @@
atomic_inc(&r10_bio->remaining);
spin_lock_irqsave(&conf->device_lock, flags);
bio_list_add(&conf->pending_bio_list, mbio);
- blk_plug_device(mddev->queue);
+ blk_plug_device_unlocked(mddev->queue);
spin_unlock_irqrestore(&conf->device_lock, flags);
}
@@ -2304,8 +2307,6 @@
if (!conf)
goto out;
- mddev->queue->queue_lock = &conf->device_lock;
-
mddev->thread = conf->thread;
conf->thread = NULL;