block: remove bio_disassociate_blkg

bio_disassociate_blkg has two callers, of which one immediately assigns
a new value to >bi_blkg.  Just open code the function in the two callers.

Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio.c

@@ -234,8 +234,12 @@ struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
 
 void bio_uninit(struct bio *bio)
 {
-	bio_disassociate_blkg(bio);
-
+#ifdef CONFIG_BLK_CGROUP
+	if (bio->bi_blkg) {
+		blkg_put(bio->bi_blkg);
+		bio->bi_blkg = NULL;
+	}
+#endif
 	if (bio_integrity(bio))
 		bio_integrity_free(bio);
 
@@ -1625,21 +1629,6 @@ EXPORT_SYMBOL(bioset_init_from_src);
 
 #ifdef CONFIG_BLK_CGROUP
 
-/**
- * bio_disassociate_blkg - puts back the blkg reference if associated
- * @bio: target bio
- *
- * Helper to disassociate the blkg from @bio if a blkg is associated.
- */
-void bio_disassociate_blkg(struct bio *bio)
-{
-	if (bio->bi_blkg) {
-		blkg_put(bio->bi_blkg);
-		bio->bi_blkg = NULL;
-	}
-}
-EXPORT_SYMBOL_GPL(bio_disassociate_blkg);
-
 /**
  * __bio_associate_blkg - associate a bio with the a blkg
  * @bio: target bio
@@ -1656,8 +1645,8 @@ EXPORT_SYMBOL_GPL(bio_disassociate_blkg);
  */
 static void __bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
 {
-	bio_disassociate_blkg(bio);
-
+	if (bio->bi_blkg)
+		blkg_put(bio->bi_blkg);
 	bio->bi_blkg = blkg_tryget_closest(blkg);
 }
 

include/linux/bio.h

@@ -497,13 +497,11 @@ static inline void bio_associate_blkg_from_page(struct bio *bio,
 #endif
 
 #ifdef CONFIG_BLK_CGROUP
-void bio_disassociate_blkg(struct bio *bio);
 void bio_associate_blkg(struct bio *bio);
 void bio_associate_blkg_from_css(struct bio *bio,
 				 struct cgroup_subsys_state *css);
 void bio_clone_blkg_association(struct bio *dst, struct bio *src);
 #else	/* CONFIG_BLK_CGROUP */
-static inline void bio_disassociate_blkg(struct bio *bio) { }
 static inline void bio_associate_blkg(struct bio *bio) { }
 static inline void bio_associate_blkg_from_css(struct bio *bio,
 					       struct cgroup_subsys_state *css)