Commit b372d360 authored by Mike Snitzer's avatar Mike Snitzer Committed by Jens Axboe
Browse files

dm: convey that all flushes are processed as empty 



Rename __clone_and_map_flush to __clone_and_map_empty_flush for added
clarity.

Simplify logic associated with REQ_FLUSH conditionals.

Introduce a BUG_ON() and add a few more helpful comments to the code
so that it is clear that all flushes are empty.

Cleanup __split_and_process_bio() so that an empty flush isn't processed
by a 'sector_count' focused while loop.

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 05447420

drivers/md/dm.c

+15 −19
Original line number Diff line number Diff line
@@ -621,16 +621,17 @@ static void dec_pending(struct dm_io *io, int error) 
		if (io_error == DM_ENDIO_REQUEUE)

			return;



		if (!(bio->bi_rw & REQ_FLUSH) || !bio->bi_size) {

			trace_block_bio_complete(md->queue, bio);

			bio_endio(bio, io_error);

		} else {

		if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {

			/*

			 * Preflush done for flush with data, reissue

			 * without REQ_FLUSH.

			 */

			bio->bi_rw &= ~REQ_FLUSH;

			queue_io(md, bio);

		} else {

			/* done with normal IO or empty flush */

			trace_block_bio_complete(md->queue, bio);

			bio_endio(bio, io_error);

		}

	}

}
@@ -1132,16 +1133,15 @@ static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti, 
		__issue_target_request(ci, ti, request_nr, len);

}



static int __clone_and_map_flush(struct clone_info *ci)

static int __clone_and_map_empty_flush(struct clone_info *ci)

{

	unsigned target_nr = 0;

	struct dm_target *ti;



	BUG_ON(bio_has_data(ci->bio));

	while ((ti = dm_table_get_target(ci->map, target_nr++)))

		__issue_target_requests(ci, ti, ti->num_flush_requests, 0);



	ci->sector_count = 0;



	return 0;

}
@@ -1282,7 +1282,6 @@ static int __clone_and_map(struct clone_info *ci) 
 */

static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)

{

	bool is_flush = bio->bi_rw & REQ_FLUSH;

	struct clone_info ci;

	int error = 0;
@@ -1302,20 +1301,17 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio) 
	ci.sector = bio->bi_sector;

	ci.idx = bio->bi_idx;



	if (!is_flush) {

	start_io_acct(ci.io);

	if (bio->bi_rw & REQ_FLUSH) {

		ci.bio = &ci.md->flush_bio;

		ci.sector_count = 0;

		error = __clone_and_map_empty_flush(&ci);

		/* dec_pending submits any data associated with flush */

	} else {

		ci.bio = bio;

		ci.sector_count = bio_sectors(bio);

	} else {

		ci.bio = &ci.md->flush_bio;

		ci.sector_count = 1;

	}



	start_io_acct(ci.io);

	while (ci.sector_count && !error) {

		if (!is_flush)

		while (ci.sector_count && !error)

			error = __clone_and_map(&ci);

		else

			error = __clone_and_map_flush(&ci);

	}



	/* drop the extra reference count */

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