Commit 4edadf6d authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: improve abnormal bio processing 



Read/write/flush are the most common operations, optimize switch in
is_abnormal_io() for those cases. Follows same pattern established in
block perf-wip commit ("block: optimise blk_may_split for normal rw")

Also, push is_abnormal_io() check and blk_queue_split() down from
dm_submit_bio() to dm_split_and_process_bio() and set new
'is_abnormal_io' flag in clone_info. Optimize __split_and_process_bio
and __process_abnormal_io by leveraging ci.is_abnormal_io flag.

Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 9d20653f

drivers/md/dm.c

+36 −31
Original line number Diff line number Diff line
@@ -84,7 +84,8 @@ struct clone_info { 
	struct dm_io *io;

	sector_t sector;

	unsigned sector_count;

	bool submit_as_polled;

	bool is_abnormal_io:1;

	bool submit_as_polled:1;

};



#define DM_TARGET_IO_BIO_OFFSET (offsetof(struct dm_target_io, clone))
@@ -1491,21 +1492,24 @@ static void __send_changing_extent_only(struct clone_info *ci, struct dm_target 


static bool is_abnormal_io(struct bio *bio)

{

	bool r = false;

	unsigned int op = bio_op(bio);



	switch (bio_op(bio)) {

	if (op != REQ_OP_READ && op != REQ_OP_WRITE && op != REQ_OP_FLUSH) {

		switch (op) {

		case REQ_OP_DISCARD:

		case REQ_OP_SECURE_ERASE:

		case REQ_OP_WRITE_ZEROES:

		r = true;

			return true;

		default:

			break;

		}

	}



	return r;

	return false;

}



static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti,

				  blk_status_t *status)

static blk_status_t __process_abnormal_io(struct clone_info *ci,

					  struct dm_target *ti)

{

	unsigned num_bios = 0;
@@ -1519,8 +1523,6 @@ static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti, 
	case REQ_OP_WRITE_ZEROES:

		num_bios = ti->num_write_zeroes_bios;

		break;

	default:

		return false;

	}



	/*
@@ -1530,12 +1532,10 @@ static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti, 
	 * check was performed.

	 */

	if (unlikely(!num_bios))

		*status = BLK_STS_NOTSUPP;

	else {

		return BLK_STS_NOTSUPP;



	__send_changing_extent_only(ci, ti, num_bios);

		*status = BLK_STS_OK;

	}

	return true;

	return BLK_STS_OK;

}



/*
@@ -1588,11 +1588,12 @@ static blk_status_t __split_and_process_bio(struct clone_info *ci) 
	struct bio *clone;

	struct dm_target *ti;

	unsigned len;

	blk_status_t error = BLK_STS_IOERR;



	ti = dm_table_find_target(ci->map, ci->sector);

	if (unlikely(!ti || __process_abnormal_io(ci, ti, &error)))

		return error;

	if (unlikely(!ti))

		return BLK_STS_IOERR;

	else if (unlikely(ci->is_abnormal_io))

		return __process_abnormal_io(ci, ti);



	/*

	 * Only support bio polling for normal IO, and the target io is
@@ -1612,11 +1613,12 @@ static blk_status_t __split_and_process_bio(struct clone_info *ci) 
}



static void init_clone_info(struct clone_info *ci, struct mapped_device *md,

			    struct dm_table *map, struct bio *bio)

			    struct dm_table *map, struct bio *bio, bool is_abnormal)

{

	ci->map = map;

	ci->io = alloc_io(md, bio);

	ci->bio = bio;

	ci->is_abnormal_io = is_abnormal;

	ci->submit_as_polled = false;

	ci->sector = bio->bi_iter.bi_sector;

	ci->sector_count = bio_sectors(bio);
@@ -1636,8 +1638,18 @@ static void dm_split_and_process_bio(struct mapped_device *md, 
	struct clone_info ci;

	struct dm_io *io;

	blk_status_t error = BLK_STS_OK;

	bool is_abnormal;



	is_abnormal = is_abnormal_io(bio);

	if (unlikely(is_abnormal)) {

		/*

		 * Use blk_queue_split() for abnormal IO (e.g. discard, etc)

		 * otherwise associated queue_limits won't be imposed.

		 */

		blk_queue_split(&bio);

	}



	init_clone_info(&ci, md, map, bio);

	init_clone_info(&ci, md, map, bio, is_abnormal);

	io = ci.io;



	if (bio->bi_opf & REQ_PREFLUSH) {
@@ -1697,13 +1709,6 @@ static void dm_submit_bio(struct bio *bio) 
		goto out;

	}



	/*

	 * Use blk_queue_split() for abnormal IO (e.g. discard, writesame, etc)

	 * otherwise associated queue_limits won't be imposed.

	 */

	if (unlikely(is_abnormal_io(bio)))

		blk_queue_split(&bio);



	dm_split_and_process_bio(md, map, bio);

out:

	dm_put_live_table_bio(md, srcu_idx, bio);