Since what the bio splitting functions do is nontrivial, document these functions.
Cc: Christoph Hellwig <[email protected]> Cc: Ming Lei <[email protected]> Cc: Hannes Reinecke <[email protected]> Signed-off-by: Bart Van Assche <[email protected]> --- block/blk-merge.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/block/blk-merge.c b/block/blk-merge.c index 1ea00da12ca3..038eaee4438a 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -192,6 +192,23 @@ static bool bvec_split_segs(const struct request_queue *q, return !!len; } +/** + * blk_bio_segment_split - split a bio in two bios + * @q: [in] request queue pointer + * @bio: [in] bio to be split + * @bs: [in] bio set to allocate the clone from + * @segs: [out] number of segments in the bio with the first half of the sectors + * + * Clones @bio, updates the bi_iter of the clone to represent the first sectors + * of @bio and updates @bio->bi_iter to represent the remaining sectors. The + * following is guaranteed for the cloned bio: + * - That it has at most get_max_io_size(@q, @bio) sectors. + * - That it has at most queue_max_segments(@q) segments. + * + * Except for discard requests the cloned bio will point at the bi_io_vec of + * the original bio. It is the responsibility of the caller to ensure that the + * original bio is not freed before the cloned bio. + */ static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, @@ -248,6 +265,16 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, return bio_split(bio, sectors, GFP_NOIO, bs); } +/** + * __blk_queue_split - split a bio and submit the second half + * @q: [in] request queue pointer + * @bio: [in, out] bio to be split + * @nr_segs: [out] number of segments in the first bio + * + * Splits a bio into two bios, chains the two bios, submits the second half + * and stores a pointer to the first half in *@bio. If the second bio is still + * too big it will be split by a recursive call to this function. + */ void __blk_queue_split(struct request_queue *q, struct bio **bio, unsigned int *nr_segs) { @@ -292,6 +319,14 @@ void __blk_queue_split(struct request_queue *q, struct bio **bio, } } +/** + * blk_queue_split - split a bio and submit the second half + * @q: [in] request queue pointer + * @bio: [in, out] bio to be split + * + * Splits a bio into two bios, chains the two bios, submits the second half + * and stores a pointer to the first half in *@bio. + */ void blk_queue_split(struct request_queue *q, struct bio **bio) { unsigned int nr_segs; -- 2.22.0.410.gd8fdbe21b5-goog
