Commit 196d38bc authored by Kent Overstreet's avatar Kent Overstreet
Browse files

block: Generic bio chaining 



This adds a generic mechanism for chaining bio completions. This is
going to be used for a bio_split() replacement, and it turns out to be
very useful in a fair amount of driver code - a fair number of drivers
were implementing this in their own roundabout ways, often painfully.

Note that this means it's no longer to call bio_endio() more than once
on the same bio! This can cause problems for drivers that save/restore
bi_end_io. Arguably they shouldn't be saving/restoring bi_end_io at all
- in all but the simplest cases they'd be better off just cloning the
bio, and immutable biovecs is making bio cloning cheaper. But for now,
we add a bio_endio_nodec() for these cases.

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
parent e90abc8e

drivers/md/bcache/io.c

+1 −1
Original line number Diff line number Diff line
@@ -133,7 +133,7 @@ static void bch_bio_submit_split_done(struct closure *cl) 


	s->bio->bi_end_io = s->bi_end_io;

	s->bio->bi_private = s->bi_private;

	bio_endio(s->bio, 0);

	bio_endio_nodec(s->bio, 0);



	closure_debug_destroy(&s->cl);

	mempool_free(s, s->p->bio_split_hook);

drivers/md/dm-cache-target.c

+6 −0
Original line number Diff line number Diff line
@@ -765,6 +765,12 @@ static void writethrough_endio(struct bio *bio, int err) 


	dm_unhook_bio(&pb->hook_info, bio);



	/*

	 * Must bump bi_remaining to allow bio to complete with

	 * restored bi_end_io.

	 */

	atomic_inc(&bio->bi_remaining);



	if (err) {

		bio_endio(bio, err);

		return;

drivers/md/dm-snap.c

+1 −0
Original line number Diff line number Diff line
@@ -1415,6 +1415,7 @@ out: 
	if (full_bio) {

		full_bio->bi_end_io = pe->full_bio_end_io;

		full_bio->bi_private = pe->full_bio_private;

		atomic_inc(&full_bio->bi_remaining);

	}

	free_pending_exception(pe);

drivers/md/dm-thin.c

+6 −2
Original line number Diff line number Diff line
@@ -611,8 +611,10 @@ static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *c 


static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)

{

	if (m->bio)

	if (m->bio) {

		m->bio->bi_end_io = m->saved_bi_end_io;

		atomic_inc(&m->bio->bi_remaining);

	}

	cell_error(m->tc->pool, m->cell);

	list_del(&m->list);

	mempool_free(m, m->tc->pool->mapping_pool);
@@ -626,8 +628,10 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m) 
	int r;



	bio = m->bio;

	if (bio)

	if (bio) {

		bio->bi_end_io = m->saved_bi_end_io;

		atomic_inc(&bio->bi_remaining);

	}



	if (m->err) {

		cell_error(pool, m->cell);

drivers/md/dm-verity.c

+1 −1
Original line number Diff line number Diff line
@@ -385,7 +385,7 @@ static void verity_finish_io(struct dm_verity_io *io, int error) 
	bio->bi_end_io = io->orig_bi_end_io;

	bio->bi_private = io->orig_bi_private;



	bio_endio(bio, error);

	bio_endio_nodec(bio, error);

}



static void verity_work(struct work_struct *w)

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