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Commit 4eb788df authored by Shaohua Li's avatar Shaohua Li Committed by NeilBrown
Browse files

raid5: reduce chance release_stripe() taking device_lock 



release_stripe() is a place conf->device_lock is heavily contended. We take the
lock even stripe count isn't 1, which isn't required.

Signed-off-by: default avatarShaohua Li <shli@fusionio.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 58e94ae1

drivers/md/raid5.c

+41 −34
Original line number Diff line number Diff line
@@ -190,9 +190,8 @@ static int stripe_operations_active(struct stripe_head *sh) 
	       test_bit(STRIPE_COMPUTE_RUN, &sh->state);

}



static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)

static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)

{

	if (atomic_dec_and_test(&sh->count)) {

	BUG_ON(!list_empty(&sh->lru));

	BUG_ON(atomic_read(&conf->active_stripes)==0);

	if (test_bit(STRIPE_HANDLE, &sh->state)) {
@@ -223,6 +222,11 @@ static void __release_stripe(struct r5conf *conf, struct stripe_head *sh) 
		}

	}

}



static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)

{

	if (atomic_dec_and_test(&sh->count))

		do_release_stripe(conf, sh);

}



static void release_stripe(struct stripe_head *sh)
@@ -230,9 +234,12 @@ static void release_stripe(struct stripe_head *sh) 
	struct r5conf *conf = sh->raid_conf;

	unsigned long flags;



	spin_lock_irqsave(&conf->device_lock, flags);

	__release_stripe(conf, sh);

	spin_unlock_irqrestore(&conf->device_lock, flags);

	local_irq_save(flags);

	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {

		do_release_stripe(conf, sh);

		spin_unlock(&conf->device_lock);

	}

	local_irq_restore(flags);

}



static inline void remove_hash(struct stripe_head *sh)