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authorMikulas Patocka <mpatocka@redhat.com>2009-12-10 18:52:13 -0500
committerAlasdair G Kergon <agk@redhat.com>2009-12-10 18:52:13 -0500
commit9ca170a3c0cbb0d5251cef6f5a3300fa436ba8ec (patch)
tree78c023bd85bcbf01b5e81ae9586093aabe201312 /drivers/md
parentc26655ca3ca7550740a63820ee981e5c7c797523 (diff)
dm kcopyd: accept zero size jobs
dm-kcopyd: accept zero-size jobs This patch changes dm-kcopyd so that it accepts zero-size jobs and completes them immediatelly via its completion thread. It is needed for multisnapshots snapshot resizing. When we are writing to a chunk beyond origin end, no copying is done. To simplify the code, we submit an empty request to kcopyd and let kcopyd complete it. If we didn't submit a request to kcopyd and called the completion routine immediatelly, it would violate the principle that completion is called only from one thread and it would need additional locking. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-kcopyd.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 3e3fc06cb861..addf83475040 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -450,7 +450,10 @@ static void dispatch_job(struct kcopyd_job *job)
450{ 450{
451 struct dm_kcopyd_client *kc = job->kc; 451 struct dm_kcopyd_client *kc = job->kc;
452 atomic_inc(&kc->nr_jobs); 452 atomic_inc(&kc->nr_jobs);
453 push(&kc->pages_jobs, job); 453 if (unlikely(!job->source.count))
454 push(&kc->complete_jobs, job);
455 else
456 push(&kc->pages_jobs, job);
454 wake(kc); 457 wake(kc);
455} 458}
456 459