From be7c99b47ff0c162f991c6eb6de4c0435dc1edea Mon Sep 17 00:00:00 2001
From: Alasdair G Kergon <agk@redhat.com>
Date: Mon, 27 Mar 2006 01:17:50 -0800
Subject: [PATCH] --- yaml --- r: 24391 b: refs/heads/master c:
 138728dc96529f20dfe970c470e51885a60e329f h: refs/heads/master i:   24389:
 b0c2f61096eddad08f8d6413a647ec5fb55b50b2   24387:
 07e50a780b2dceb006cb4b11819a5fe727ebc903   24383:
 570ed27c6181c68502f142bc64cd24f5201bc002 v: v3

---
 [refs]                     |  2 +-
 trunk/drivers/md/dm-snap.c |  6 +++++-
 trunk/drivers/md/kcopyd.c  | 17 ++++++++++++++++-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index 4ac5477ad4c9..d6125c33cb12 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 969429b504ae866d3f8b1cafd68a2c099e305093
+refs/heads/master: 138728dc96529f20dfe970c470e51885a60e329f
diff --git a/trunk/drivers/md/dm-snap.c b/trunk/drivers/md/dm-snap.c
index a5765f9fbe02..08312b46463a 100644
--- a/trunk/drivers/md/dm-snap.c
+++ b/trunk/drivers/md/dm-snap.c
@@ -559,8 +559,12 @@ static void snapshot_dtr(struct dm_target *ti)
 {
 	struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
 
+	/* Prevent further origin writes from using this snapshot. */
+	/* After this returns there can be no new kcopyd jobs. */
 	unregister_snapshot(s);
 
+	kcopyd_client_destroy(s->kcopyd_client);
+
 	exit_exception_table(&s->pending, pending_cache);
 	exit_exception_table(&s->complete, exception_cache);
 
@@ -569,7 +573,7 @@ static void snapshot_dtr(struct dm_target *ti)
 
 	dm_put_device(ti, s->origin);
 	dm_put_device(ti, s->cow);
-	kcopyd_client_destroy(s->kcopyd_client);
+
 	kfree(s);
 }
 
diff --git a/trunk/drivers/md/kcopyd.c b/trunk/drivers/md/kcopyd.c
index 9dcb2c8a3853..ed71f3f94620 100644
--- a/trunk/drivers/md/kcopyd.c
+++ b/trunk/drivers/md/kcopyd.c
@@ -44,6 +44,9 @@ struct kcopyd_client {
 	struct page_list *pages;
 	unsigned int nr_pages;
 	unsigned int nr_free_pages;
+
+	wait_queue_head_t destroyq;
+	atomic_t nr_jobs;
 };
 
 static struct page_list *alloc_pl(void)
@@ -292,10 +295,15 @@ static int run_complete_job(struct kcopyd_job *job)
 	int read_err = job->read_err;
 	unsigned int write_err = job->write_err;
 	kcopyd_notify_fn fn = job->fn;
+	struct kcopyd_client *kc = job->kc;
 
-	kcopyd_put_pages(job->kc, job->pages);
+	kcopyd_put_pages(kc, job->pages);
 	mempool_free(job, _job_pool);
 	fn(read_err, write_err, context);
+
+	if (atomic_dec_and_test(&kc->nr_jobs))
+		wake_up(&kc->destroyq);
+
 	return 0;
 }
 
@@ -430,6 +438,7 @@ static void do_work(void *ignored)
  */
 static void dispatch_job(struct kcopyd_job *job)
 {
+	atomic_inc(&job->kc->nr_jobs);
 	push(&_pages_jobs, job);
 	wake();
 }
@@ -669,6 +678,9 @@ int kcopyd_client_create(unsigned int nr_pages, struct kcopyd_client **result)
 		return r;
 	}
 
+	init_waitqueue_head(&kc->destroyq);
+	atomic_set(&kc->nr_jobs, 0);
+
 	client_add(kc);
 	*result = kc;
 	return 0;
@@ -676,6 +688,9 @@ int kcopyd_client_create(unsigned int nr_pages, struct kcopyd_client **result)
 
 void kcopyd_client_destroy(struct kcopyd_client *kc)
 {
+	/* Wait for completion of all jobs submitted by this client. */
+	wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));
+
 	dm_io_put(kc->nr_pages);
 	client_free_pages(kc);
 	client_del(kc);