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>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a42dfb7..30f5dc8 100644 (file)
--- 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;