dm: abstract clone_rq

This patch factors out the request cloning code in dm_prep_fn()
as clone_rq().  No functional change.

This patch is a preparation for a later patch in this series which needs to
make clones from an original barrier request.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 28 insertions, 17 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a42dfb7a718e..30f5dc8e52bc 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1445,6 +1445,32 @@ static int setup_clone(struct request *clone, struct request *rq,
         return 0;
 }
 
+static struct request *clone_rq(struct request *rq, struct mapped_device *md,
+                                gfp_t gfp_mask)
+{
+        struct request *clone;
+        struct dm_rq_target_io *tio;
+
+        tio = alloc_rq_tio(md, gfp_mask);
+        if (!tio)
+                return NULL;
+
+        tio->md = md;
+        tio->ti = NULL;
+        tio->orig = rq;
+        tio->error = 0;
+        memset(&tio->info, 0, sizeof(tio->info));
+
+        clone = &tio->clone;
+        if (setup_clone(clone, rq, tio)) {
+                /* -ENOMEM */
+                free_rq_tio(tio);
+                return NULL;
+        }
+
+        return clone;
+}
+
 static int dm_rq_flush_suspending(struct mapped_device *md)
 {
         return !md->suspend_rq.special;
@@ -1456,7 +1482,6 @@ static int dm_rq_flush_suspending(struct mapped_device *md)
 static int dm_prep_fn(struct request_queue *q, struct request *rq)
 {
         struct mapped_device *md = q->queuedata;
-        struct dm_rq_target_io *tio;
         struct request *clone;
 
         if (unlikely(rq == &md->suspend_rq)) {
@@ -1472,24 +1497,10 @@ static int dm_prep_fn(struct request_queue *q, struct request *rq)
                 return BLKPREP_KILL;
         }
 
-        tio = alloc_rq_tio(md, GFP_ATOMIC);
-        if (!tio)
-                /* -ENOMEM */
+        clone = clone_rq(rq, md, GFP_ATOMIC);
+        if (!clone)
                 return BLKPREP_DEFER;
 
-        tio->md = md;
-        tio->ti = NULL;
-        tio->orig = rq;
-        tio->error = 0;
-        memset(&tio->info, 0, sizeof(tio->info));
-
-        clone = &tio->clone;
-        if (setup_clone(clone, rq, tio)) {
-                /* -ENOMEM */
-                free_rq_tio(tio);
-                return BLKPREP_DEFER;
-        }
-
         rq->special = clone;
         rq->cmd_flags |= REQ_DONTPREP;