dm kcopyd: add dm_kcopyd_zero to zero an area
This patch introduces dm_kcopyd_zero() to make it easy to use
kcopyd to write zeros into the requested areas instead
instead of copying. It is implemented by passing a NULL
copying source to dm_kcopyd_copy().
The forthcoming thin provisioning target uses this.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 32ac708..bed444c 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -66,6 +66,8 @@
struct list_head pages_jobs;
};
+static struct page_list zero_page_list;
+
static void wake(struct dm_kcopyd_client *kc)
{
queue_work(kc->kcopyd_wq, &kc->kcopyd_work);
@@ -254,6 +256,9 @@
if (!_job_cache)
return -ENOMEM;
+ zero_page_list.next = &zero_page_list;
+ zero_page_list.page = ZERO_PAGE(0);
+
return 0;
}
@@ -322,7 +327,7 @@
dm_kcopyd_notify_fn fn = job->fn;
struct dm_kcopyd_client *kc = job->kc;
- if (job->pages)
+ if (job->pages && job->pages != &zero_page_list)
kcopyd_put_pages(kc, job->pages);
/*
* If this is the master job, the sub jobs have already
@@ -484,6 +489,8 @@
atomic_inc(&kc->nr_jobs);
if (unlikely(!job->source.count))
push(&kc->complete_jobs, job);
+ else if (job->pages == &zero_page_list)
+ push(&kc->io_jobs, job);
else
push(&kc->pages_jobs, job);
wake(kc);
@@ -592,14 +599,20 @@
job->flags = flags;
job->read_err = 0;
job->write_err = 0;
- job->rw = READ;
-
- job->source = *from;
job->num_dests = num_dests;
memcpy(&job->dests, dests, sizeof(*dests) * num_dests);
- job->pages = NULL;
+ if (from) {
+ job->source = *from;
+ job->pages = NULL;
+ job->rw = READ;
+ } else {
+ memset(&job->source, 0, sizeof job->source);
+ job->source.count = job->dests[0].count;
+ job->pages = &zero_page_list;
+ job->rw = WRITE;
+ }
job->fn = fn;
job->context = context;
@@ -617,6 +630,14 @@
}
EXPORT_SYMBOL(dm_kcopyd_copy);
+int dm_kcopyd_zero(struct dm_kcopyd_client *kc,
+ unsigned num_dests, struct dm_io_region *dests,
+ unsigned flags, dm_kcopyd_notify_fn fn, void *context)
+{
+ return dm_kcopyd_copy(kc, NULL, num_dests, dests, flags, fn, context);
+}
+EXPORT_SYMBOL(dm_kcopyd_zero);
+
void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
dm_kcopyd_notify_fn fn, void *context)
{