md/raid5: call bio_endio() directly rather than queueing for later.

We currently gather bios that need to be returned into a bio_list
and call bio_endio() on them all together.
The original reason for this was to avoid making the calls while
holding a spinlock.
Locking has changed a lot since then, and that reason is no longer
valid.

So discard return_io() and various return_bi lists, and just call
bio_endio() directly as needed.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index 4f5a0f4..738930f 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -21,7 +21,7 @@
 extern void r5c_use_extra_page(struct stripe_head *sh);
 extern void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
 extern void r5c_handle_cached_data_endio(struct r5conf *conf,
-	struct stripe_head *sh, int disks, struct bio_list *return_bi);
+	struct stripe_head *sh, int disks);
 extern int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh);
 extern void r5c_make_stripe_write_out(struct stripe_head *sh);
 extern void r5c_flush_cache(struct r5conf *conf, int num);