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md: avoid spinlock problem in blk_throtl_exit

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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>
This commit is contained in:
NeilBrown
2011-02-21 18:25:57 +11:00
parent 8f5f02c460
commit da9cf5050a
6 changed files with 8 additions and 9 deletions
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7
drivers/md/raid10.c
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@@ -662,7 +662,10 @@ static int flush_pending_writes(conf_t *conf)
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 @@ static int make_request(mddev_t *mddev, struct bio * bio)
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 @@ static int run(mddev_t *mddev)
if (!conf)
goto out;
mddev->queue->queue_lock = &conf->device_lock;
mddev->thread = conf->thread;
conf->thread = NULL;