[dm-devel] [PATCH v3 2/3] block: allow use of per-cpu bio alloc cache by block drivers

[Mike Snitzer]

Refine per-cpu bio alloc cache interfaces so that DM and other block
drivers can properly create and use the cache:

DM uses bioset_init_from_src() to do its final bioset initialization,
so must update bioset_init_from_src() to set BIOSET_PERCPU_CACHE if
%src bioset has a cache.

Also move bio_clear_polled() to include/linux/bio.h to allow users
outside of block core.

Signed-off-by: Mike Snitzer <snitzer at kernel.org>
---
 block/bio.c         | 2 ++
 block/blk.h         | 6 ------
 include/linux/bio.h | 6 ++++++
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 09b714469b06..859f728e42dc 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1769,6 +1769,8 @@ int bioset_init_from_src(struct bio_set *bs, struct bio_set *src)
 		flags |= BIOSET_NEED_BVECS;
 	if (src->rescue_workqueue)
 		flags |= BIOSET_NEED_RESCUER;
+	if (src->cache)
+		flags |= BIOSET_PERCPU_CACHE;
 
 	return bioset_init(bs, src->bio_pool.min_nr, src->front_pad, flags);
 }
diff --git a/block/blk.h b/block/blk.h
index 9cb04f24ba8a..4f6b172c3342 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -451,12 +451,6 @@ extern struct device_attribute dev_attr_events;
 extern struct device_attribute dev_attr_events_async;
 extern struct device_attribute dev_attr_events_poll_msecs;
 
-static inline void bio_clear_polled(struct bio *bio)
-{
-	/* can't support alloc cache if we turn off polling */
-	bio->bi_opf &= ~(REQ_POLLED | REQ_ALLOC_CACHE);
-}
-
 long blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg);
 long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg);
 
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 10406f57d339..a40a4ba2771f 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -783,6 +783,12 @@ static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
 		bio->bi_opf |= REQ_NOWAIT;
 }
 
+static inline void bio_clear_polled(struct bio *bio)
+{
+	/* can't support alloc cache if we turn off polling */
+	bio->bi_opf &= ~(REQ_POLLED | REQ_ALLOC_CACHE);
+}
+
 struct bio *blk_next_bio(struct bio *bio, struct block_device *bdev,
 		unsigned int nr_pages, unsigned int opf, gfp_t gfp);
 
-- 
2.15.0