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authorAlasdair G Kergon <agk@redhat.com>2006-03-27 01:17:50 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-27 08:44:59 -0800
commit138728dc96529f20dfe970c470e51885a60e329f (patch)
treea0369a9de402cd8b9a123129c5e8ba7c69ba1a95 /drivers
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>
Diffstat (limited to 'drivers')
-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 a5765f9fbe0..08312b46463 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)
{
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/drivers/md/kcopyd.c b/drivers/md/kcopyd.c
index 9dcb2c8a385..ed71f3f9462 100644
--- a/drivers/md/kcopyd.c
+++ b/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);