[PATCH]md:dm.c Fix warning: statement with no effect

["Justin P. Mattock" <justinmattock@gmail.com>]

Ive noticed that having CONFIG_BLK_DEV_INTEGRITY=n I get warning messages generated by GCC(below)
  CC      drivers/md/dm.o
drivers/md/dm.c: In function 'split_bvec':
drivers/md/dm.c:1117:3: warning: statement with no effect
drivers/md/dm.c: In function 'clone_bio':
drivers/md/dm.c:1145:3: warning: statement with no effect

adding in some #ifdef's fixes this warning if someone chooses not to have 
CONFIG_BLK_DEV_INTEGRITY turned on. but keep in mind not sure if this is the best approach
i.e. should something be done in bio.h? 
Also this patch fixes a comment which was hard to read at first. Anyways have a look 
when you have time, and let me know.

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>

---
 drivers/md/dm.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index d21e128..7c1cb04 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1091,7 +1091,7 @@ static void dm_bio_destructor(struct bio *bio)
 }
 
 /*
- * Creates a little bio that is just does part of a bvec.
+ * Create a little bio that just does part of a bvec.
  */
 static struct bio *split_bvec(struct bio *bio, sector_t sector,
 			      unsigned short idx, unsigned int offset,
@@ -1114,7 +1114,9 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector,
 	clone->bi_flags |= 1 << BIO_CLONED;
 
 	if (bio_integrity(bio)) {
+#ifdef CONFIG_BLK_DEV_INTEGRITY
 		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
+#endif
 		bio_integrity_trim(clone,
 				   bio_sector_offset(bio, idx, offset), len);
 	}
@@ -1142,7 +1144,9 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector,
 	clone->bi_flags &= ~(1 << BIO_SEG_VALID);
 
 	if (bio_integrity(bio)) {
+#ifdef CONFIG_BLK_DEV_INTEGRITY
 		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
+#endif
 
 		if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
 			bio_integrity_trim(clone,
-- 
1.7.1.rc1.21.gf3bd6