Commit 9d20653f authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: simplify bio-based IO accounting further 



Now that io splitting is recorded prior to, or during, ->map IO
accounting can happen immediately rather than defer until after
bio splitting in dm_split_and_process_bio().

Remove the DM_IO_START_ACCT flag and also remove dm_io's map_task
member because there is no longer any need to wait for splitting to
occur before accounting.

Also move dm_io struct's 'flags' member to consolidate struct holes.

Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent ec211631

drivers/md/dm-core.h

+1 −5
Original line number Diff line number Diff line
@@ -255,15 +255,12 @@ static inline bool dm_tio_is_normal(struct dm_target_io *tio) 
#define DM_IO_MAGIC 19577

struct dm_io {

	unsigned short magic;



	blk_short_t flags;

	spinlock_t lock;

	unsigned long start_time;

	void *data;

	struct dm_io *next;

	struct task_struct *map_task;

	struct dm_stats_aux stats_aux;



	blk_short_t flags;

	blk_status_t status;

	atomic_t io_count;

	struct mapped_device *md;
@@ -281,7 +278,6 @@ struct dm_io { 
 * dm_io flags

 */

enum {

	DM_IO_START_ACCT,

	DM_IO_ACCOUNTED,

	DM_IO_WAS_SPLIT

};

drivers/md/dm.c

+5 −29
Original line number Diff line number Diff line
@@ -596,7 +596,6 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio) 
	this_cpu_inc(*md->pending_io);

	io->orig_bio = bio;

	io->md = md;

	io->map_task = current;

	spin_lock_init(&io->lock);

	io->start_time = jiffies;

	io->flags = 0;
@@ -1241,13 +1240,6 @@ void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors) 
}

EXPORT_SYMBOL_GPL(dm_accept_partial_bio);



static inline void __dm_submit_bio_remap(struct bio *clone,

					 dev_t dev, sector_t old_sector)

{

	trace_block_bio_remap(clone, dev, old_sector);

	submit_bio_noacct(clone);

}



/*

 * @clone: clone bio that DM core passed to target's .map function

 * @tgt_clone: clone of @clone bio that target needs submitted
@@ -1262,8 +1254,6 @@ void dm_submit_bio_remap(struct bio *clone, struct bio *tgt_clone) 
	struct dm_target_io *tio = clone_to_tio(clone);

	struct dm_io *io = tio->io;



	WARN_ON_ONCE(!tio->ti->accounts_remapped_io);



	/* establish bio that will get submitted */

	if (!tgt_clone)

		tgt_clone = clone;
@@ -1272,15 +1262,11 @@ void dm_submit_bio_remap(struct bio *clone, struct bio *tgt_clone) 
	 * Account io->origin_bio to DM dev on behalf of target

	 * that took ownership of IO with DM_MAPIO_SUBMITTED.

	 */

	if (io->map_task == current) {

		/* Still in target's map function */

		dm_io_set_flag(io, DM_IO_START_ACCT);

	} else {

	dm_start_io_acct(io, clone);

	}



	__dm_submit_bio_remap(tgt_clone, disk_devt(io->md->disk),

	trace_block_bio_remap(tgt_clone, disk_devt(io->md->disk),

			      tio->old_sector);

	submit_bio_noacct(tgt_clone);

}

EXPORT_SYMBOL_GPL(dm_submit_bio_remap);
@@ -1340,16 +1326,10 @@ static void __map_bio(struct bio *clone) 
	case DM_MAPIO_SUBMITTED:

		/* target has assumed ownership of this io */

		if (!ti->accounts_remapped_io)

			dm_io_set_flag(io, DM_IO_START_ACCT);

			dm_start_io_acct(io, clone);

		break;

	case DM_MAPIO_REMAPPED:

		/*

		 * the bio has been remapped so dispatch it, but defer

		 * dm_start_io_acct() until after possible bio_split().

		 */

		__dm_submit_bio_remap(clone, disk_devt(md->disk),

				      tio->old_sector);

		dm_io_set_flag(io, DM_IO_START_ACCT);

		dm_submit_bio_remap(clone, NULL);

		break;

	case DM_MAPIO_KILL:

	case DM_MAPIO_REQUEUE:
@@ -1667,7 +1647,6 @@ static void dm_split_and_process_bio(struct mapped_device *md, 
	}



	error = __split_and_process_bio(&ci);

	io->map_task = NULL;

	if (error || !ci.sector_count)

		goto out;

	/*
@@ -1679,9 +1658,6 @@ static void dm_split_and_process_bio(struct mapped_device *md, 
	bio_inc_remaining(bio);

	submit_bio_noacct(bio);

out:

	if (dm_io_flagged(io, DM_IO_START_ACCT))

		dm_start_io_acct(io, NULL);



	/*

	 * Drop the extra reference count for non-POLLED bio, and hold one

	 * reference for POLLED bio, which will be released in dm_poll_bio