block: allow use of per-cpu bio alloc cache by block drivers

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@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220324203526.62306-3-snitzer@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 0fe8a51a0778..8e87f3065042 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -780,6 +780,12 @@ 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);