Commit 238f8363 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm cache: improve efficiency of quiescing flag management 



Make the quiescing flag an atomic_t and stop protecting it with a spin
lock.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 66cb1910

drivers/md/dm-cache-target.c

+5 −22
Original line number Diff line number Diff line
@@ -149,6 +149,7 @@ struct cache { 
	atomic_t nr_migrations;



	wait_queue_head_t quiescing_wait;

	atomic_t quiescing;

	atomic_t quiescing_ack;



	/*
@@ -189,7 +190,6 @@ struct cache { 


	bool need_tick_bio:1;

	bool sized:1;

	bool quiescing:1;

	bool commit_requested:1;

	bool loaded_mappings:1;

	bool loaded_discards:1;
@@ -1353,14 +1353,7 @@ static void writeback_some_dirty_blocks(struct cache *cache) 
 *--------------------------------------------------------------*/

static bool is_quiescing(struct cache *cache)

{

	int r;

	unsigned long flags;



	spin_lock_irqsave(&cache->lock, flags);

	r = cache->quiescing;

	spin_unlock_irqrestore(&cache->lock, flags);



	return r;

	return atomic_read(&cache->quiescing);

}



static void ack_quiescing(struct cache *cache)
@@ -1378,23 +1371,13 @@ static void wait_for_quiescing_ack(struct cache *cache) 


static void start_quiescing(struct cache *cache)

{

	unsigned long flags;



	spin_lock_irqsave(&cache->lock, flags);

	cache->quiescing = true;

	spin_unlock_irqrestore(&cache->lock, flags);



	atomic_inc(&cache->quiescing);

	wait_for_quiescing_ack(cache);

}



static void stop_quiescing(struct cache *cache)

{

	unsigned long flags;



	spin_lock_irqsave(&cache->lock, flags);

	cache->quiescing = false;

	spin_unlock_irqrestore(&cache->lock, flags);



	atomic_set(&cache->quiescing, 0);

	atomic_set(&cache->quiescing_ack, 0);

}
@@ -2030,6 +2013,7 @@ static int cache_create(struct cache_args *ca, struct cache **result) 
	init_waitqueue_head(&cache->migration_wait);



	init_waitqueue_head(&cache->quiescing_wait);

	atomic_set(&cache->quiescing, 0);

	atomic_set(&cache->quiescing_ack, 0);



	r = -ENOMEM;
@@ -2091,7 +2075,6 @@ static int cache_create(struct cache_args *ca, struct cache **result) 


	cache->need_tick_bio = true;

	cache->sized = false;

	cache->quiescing = false;

	cache->commit_requested = false;

	cache->loaded_mappings = false;

	cache->loaded_discards = false;