1 files changed, 14 insertions, 4 deletions

diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index bed444c93d8d..68c02673263b 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -349,7 +349,7 @@ static void complete_io(unsigned long error, void *context)
         struct dm_kcopyd_client *kc = job->kc;
 
         if (error) {
-                if (job->rw == WRITE)
+                if (job->rw & WRITE)
                         job->write_err |= error;
                 else
                         job->read_err = 1;
@@ -361,7 +361,7 @@ static void complete_io(unsigned long error, void *context)
                 }
         }
 
-        if (job->rw == WRITE)
+        if (job->rw & WRITE)
                 push(&kc->complete_jobs, job);
 
         else {
@@ -432,7 +432,7 @@ static int process_jobs(struct list_head *jobs, struct dm_kcopyd_client *kc,
 
                 if (r < 0) {
                         /* error this rogue job */
-                        if (job->rw == WRITE)
+                        if (job->rw & WRITE)
                                 job->write_err = (unsigned long) -1L;
                         else
                                 job->read_err = 1;
@@ -585,6 +585,7 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
                    unsigned int flags, dm_kcopyd_notify_fn fn, void *context)
 {
         struct kcopyd_job *job;
+        int i;
 
         /*
          * Allocate an array of jobs consisting of one master job
@@ -611,7 +612,16 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
                 memset(&job->source, 0, sizeof job->source);
                 job->source.count = job->dests[0].count;
                 job->pages = &zero_page_list;
-                job->rw = WRITE;
+
+                /*
+                 * Use WRITE SAME to optimize zeroing if all dests support it.
+                 */
+                job->rw = WRITE | REQ_WRITE_SAME;
+                for (i = 0; i < job->num_dests; i++)
+                        if (!bdev_write_same(job->dests[i].bdev)) {
+                                job->rw = WRITE;
+                                break;
+                        }
         }
 
         job->fn = fn;