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authorAlasdair G Kergon <agk@redhat.com>2006-03-27 04:17:50 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-27 11:44:59 -0500
commit138728dc96529f20dfe970c470e51885a60e329f (patch)
treea0369a9de402cd8b9a123129c5e8ba7c69ba1a95
parent969429b504ae866d3f8b1cafd68a2c099e305093 (diff)
[PATCH] dm snapshot: fix kcopyd destructor
Before removing a snapshot, wait for the completion of any kcopyd jobs using it. Do this by maintaining a count (nr_jobs) of how many outstanding jobs each kcopyd_client has. The snapshot destructor first unregisters the snapshot so that no new kcopyd jobs (created by writes to the origin) will reference that particular snapshot. kcopyd_client_destroy() is now run next to wait for the completion of any outstanding jobs before the snapshot exception structures (that those jobs reference) are freed. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/md/dm-snap.c6
-rw-r--r--drivers/md/kcopyd.c17
2 files changed, 21 insertions, 2 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index a5765f9fbe02..08312b46463a 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -559,8 +559,12 @@ static void snapshot_dtr(struct dm_target *ti)
559{ 559{
560 struct dm_snapshot *s = (struct dm_snapshot *) ti->private; 560 struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
561 561
562 /* Prevent further origin writes from using this snapshot. */
563 /* After this returns there can be no new kcopyd jobs. */
562 unregister_snapshot(s); 564 unregister_snapshot(s);
563 565
566 kcopyd_client_destroy(s->kcopyd_client);
567
564 exit_exception_table(&s->pending, pending_cache); 568 exit_exception_table(&s->pending, pending_cache);
565 exit_exception_table(&s->complete, exception_cache); 569 exit_exception_table(&s->complete, exception_cache);
566 570
@@ -569,7 +573,7 @@ static void snapshot_dtr(struct dm_target *ti)
569 573
570 dm_put_device(ti, s->origin); 574 dm_put_device(ti, s->origin);
571 dm_put_device(ti, s->cow); 575 dm_put_device(ti, s->cow);
572 kcopyd_client_destroy(s->kcopyd_client); 576
573 kfree(s); 577 kfree(s);
574} 578}
575 579
diff --git a/drivers/md/kcopyd.c b/drivers/md/kcopyd.c
index 9dcb2c8a3853..ed71f3f94620 100644
--- a/drivers/md/kcopyd.c
+++ b/drivers/md/kcopyd.c
@@ -44,6 +44,9 @@ struct kcopyd_client {
44 struct page_list *pages; 44 struct page_list *pages;
45 unsigned int nr_pages; 45 unsigned int nr_pages;
46 unsigned int nr_free_pages; 46 unsigned int nr_free_pages;
47
48 wait_queue_head_t destroyq;
49 atomic_t nr_jobs;
47}; 50};
48 51
49static struct page_list *alloc_pl(void) 52static struct page_list *alloc_pl(void)
@@ -292,10 +295,15 @@ static int run_complete_job(struct kcopyd_job *job)
292 int read_err = job->read_err; 295 int read_err = job->read_err;
293 unsigned int write_err = job->write_err; 296 unsigned int write_err = job->write_err;
294 kcopyd_notify_fn fn = job->fn; 297 kcopyd_notify_fn fn = job->fn;
298 struct kcopyd_client *kc = job->kc;
295 299
296 kcopyd_put_pages(job->kc, job->pages); 300 kcopyd_put_pages(kc, job->pages);
297 mempool_free(job, _job_pool); 301 mempool_free(job, _job_pool);
298 fn(read_err, write_err, context); 302 fn(read_err, write_err, context);
303
304 if (atomic_dec_and_test(&kc->nr_jobs))
305 wake_up(&kc->destroyq);
306
299 return 0; 307 return 0;
300} 308}
301 309
@@ -430,6 +438,7 @@ static void do_work(void *ignored)
430 */ 438 */
431static void dispatch_job(struct kcopyd_job *job) 439static void dispatch_job(struct kcopyd_job *job)
432{ 440{
441 atomic_inc(&job->kc->nr_jobs);
433 push(&_pages_jobs, job); 442 push(&_pages_jobs, job);
434 wake(); 443 wake();
435} 444}
@@ -669,6 +678,9 @@ int kcopyd_client_create(unsigned int nr_pages, struct kcopyd_client **result)
669 return r; 678 return r;
670 } 679 }
671 680
681 init_waitqueue_head(&kc->destroyq);
682 atomic_set(&kc->nr_jobs, 0);
683
672 client_add(kc); 684 client_add(kc);
673 *result = kc; 685 *result = kc;
674 return 0; 686 return 0;
@@ -676,6 +688,9 @@ int kcopyd_client_create(unsigned int nr_pages, struct kcopyd_client **result)
676 688
677void kcopyd_client_destroy(struct kcopyd_client *kc) 689void kcopyd_client_destroy(struct kcopyd_client *kc)
678{ 690{
691 /* Wait for completion of all jobs submitted by this client. */
692 wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));
693
679 dm_io_put(kc->nr_pages); 694 dm_io_put(kc->nr_pages);
680 client_free_pages(kc); 695 client_free_pages(kc);
681 client_del(kc); 696 client_del(kc);