New function blk_req_append_bio

ll_back_merge_fn is currently exported to SCSI where is it used,
together with blk_rq_bio_prep, in exactly the same way these
functions are used in __blk_rq_map_user.

So move the common code into a new function (blk_rq_append_bio), and
don't export ll_back_merge_fn any longer.

Signed-off-by: Neil Brown <neilb@suse.de>

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

3 files changed, 25 insertions, 28 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 094c0fa5c405..2de9bad1d042 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1441,7 +1441,8 @@ static inline int ll_new_hw_segment(struct request_queue *q,
         return 1;
 }
 
-int ll_back_merge_fn(struct request_queue *q, struct request *req, struct bio *bio)
+static int ll_back_merge_fn(struct request_queue *q, struct request *req,
+                            struct bio *bio)
 {
         unsigned short max_sectors;
         int len;
@@ -1477,7 +1478,6 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req, struct bio *b
 
         return ll_new_hw_segment(q, req, bio);
 }
-EXPORT_SYMBOL(ll_back_merge_fn);
 
 static int ll_front_merge_fn(struct request_queue *q, struct request *req, 
                              struct bio *bio)
@@ -2367,6 +2367,23 @@ static int __blk_rq_unmap_user(struct bio *bio)
         return ret;
 }
 
+int blk_rq_append_bio(struct request_queue *q, struct request *rq,
+                      struct bio *bio)
+{
+        if (!rq->bio)
+                blk_rq_bio_prep(q, rq, bio);
+        else if (!ll_back_merge_fn(q, rq, bio))
+                return -EINVAL;
+        else {
+                rq->biotail->bi_next = bio;
+                rq->biotail = bio;
+
+                rq->data_len += bio->bi_size;
+        }
+        return 0;
+}
+EXPORT_SYMBOL(blk_rq_append_bio);
+
 static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
                              void __user *ubuf, unsigned int len)
 {
@@ -2398,21 +2415,10 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
          */
         bio_get(bio);
 
-        if (!rq->bio)
-                blk_rq_bio_prep(q, rq, bio);
-        else if (!ll_back_merge_fn(q, rq, bio)) {
-                ret = -EINVAL;
-                goto unmap_bio;
-        } else {
-                rq->biotail->bi_next = bio;
-                rq->biotail = bio;
-
-                rq->data_len += bio->bi_size;
-        }
-
-        return bio->bi_size;
+        ret = blk_rq_append_bio(q, rq, bio);
+        if (!ret)
+                return bio->bi_size;
 
-unmap_bio:
         /* if it was boucned we must call the end io function */
         bio_endio(bio, bio->bi_size, 0);
         __blk_rq_unmap_user(orig_bio);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a417a6ff9f97..59b398530295 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -263,16 +263,7 @@ static int scsi_merge_bio(struct request *rq, struct bio *bio)
                 bio->bi_rw |= (1 << BIO_RW);
         blk_queue_bounce(q, &bio);
 
-        if (!rq->bio)
-                blk_rq_bio_prep(q, rq, bio);
-        else if (!ll_back_merge_fn(q, rq, bio))
-                return -EINVAL;
-        else {
-                rq->biotail->bi_next = bio;
-                rq->biotail = bio;
-        }
-
-        return 0;
+        return blk_rq_append_bio(q, rq, bio);
 }
 
 static int scsi_bi_endio(struct bio *bio, unsigned int bytes_done, int error)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a4b13b8a9d09..3021a5b1d392 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -675,8 +675,8 @@ extern int sg_scsi_ioctl(struct file *, struct request_queue *,
 /*
  * Temporary export, until SCSI gets fixed up.
  */
-extern int ll_back_merge_fn(struct request_queue *, struct request *,
-                struct bio *);
+extern int blk_rq_append_bio(struct request_queue *q, struct request *rq,
+                             struct bio *bio);
 
 /*
  * A queue has just exitted congestion.  Note this in the global counter of