Commit cb6934f8 authored by Jens Axboe's avatar Jens Axboe
Browse files

block: add support for write hints in a bio 



No functional changes in this patch, we just use up some holes
in the bio and request structures to define a write hint that
we psas down the stack.

Ensure that we don't merge requests that have different life time
hints assigned to them, and that we inherit the write hint when
cloning a bio.

Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c75b1d94

block/bio.c

+2 −0
Original line number Diff line number Diff line
@@ -596,6 +596,7 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src) 
	bio->bi_bdev = bio_src->bi_bdev;

	bio_set_flag(bio, BIO_CLONED);

	bio->bi_opf = bio_src->bi_opf;

	bio->bi_write_hint = bio_src->bi_write_hint;

	bio->bi_iter = bio_src->bi_iter;

	bio->bi_io_vec = bio_src->bi_io_vec;
@@ -679,6 +680,7 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask, 
		return NULL;

	bio->bi_bdev		= bio_src->bi_bdev;

	bio->bi_opf		= bio_src->bi_opf;

	bio->bi_write_hint	= bio_src->bi_write_hint;

	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;

	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;

block/blk-core.c

+1 −0
Original line number Diff line number Diff line
@@ -1765,6 +1765,7 @@ void blk_init_request_from_bio(struct request *req, struct bio *bio) 
		req->ioprio = ioc->ioprio;

	else

		req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);

	req->write_hint = bio->bi_write_hint;

	blk_rq_bio_prep(req->q, req, bio);

}

EXPORT_SYMBOL_GPL(blk_init_request_from_bio);

block/blk-merge.c

+14 −0
Original line number Diff line number Diff line
@@ -672,6 +672,13 @@ static struct request *attempt_merge(struct request_queue *q, 
	    !blk_write_same_mergeable(req->bio, next->bio))

		return NULL;



	/*

	 * Don't allow merge of different write hints, or for a hint with

	 * non-hint IO.

	 */

	if (req->write_hint != next->write_hint)

		return NULL;



	/*

	 * If we are allowed to merge, then append bio list

	 * from next to rq and release next. merge_requests_fn
@@ -791,6 +798,13 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 
	    !blk_write_same_mergeable(rq->bio, bio))

		return false;



	/*

	 * Don't allow merge of different write hints, or for a hint with

	 * non-hint IO.

	 */

	if (rq->write_hint != bio->bi_write_hint)

		return false;



	return true;

}

include/linux/blk_types.h

+1 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ struct bio { 
						 */

	unsigned short		bi_flags;	/* status, etc and bvec pool number */

	unsigned short		bi_ioprio;

	unsigned short		bi_write_hint;



	struct bvec_iter	bi_iter;

include/linux/blkdev.h

+2 −0
Original line number Diff line number Diff line
@@ -225,6 +225,8 @@ struct request { 


	unsigned int extra_len;	/* length of alignment and padding */



	unsigned short write_hint;



	unsigned long deadline;

	struct list_head timeout_list;

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