Commit 7dd06a25 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: allow dm_accept_partial_bio() for dm_io without duplicate bios 



The intent behind commit e6fc9f62 ("dm: flag clones created by
__send_duplicate_bios") was to formally disallow the use of
dm_accept_partial_bio() where it simply isn't possible -- due to
constraint that multiple bios cannot meaningfully update a shared
tio->len_ptr.

But that commit went too far and disallowed the case where "abormal"
IO (e.g. WRITE_ZEROES) is only using a single bio.  Fix this by
not marking a dm_io with a single dm_target_io (and bio), that happens
to be created by __send_duplicate_bios, as DM_TIO_IS_DUPLICATE_BIO.
Also remove 'unsigned *len' parameter from alloc_multiple_bios().

This commit fixes a dm_accept_partial_bio() BUG_ON() with dm-zoned
when a WRITE_ZEROES bio is issued.

Fixes: 655f3aad ("dm: switch dm_target_io booleans over to proper flags")
Reported-by: default avatarShinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: default avatarDamien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 73d7b06e

drivers/md/dm.c

+6 −11
Original line number Diff line number Diff line
@@ -1323,8 +1323,7 @@ static void __map_bio(struct bio *clone) 
}



static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,

				struct dm_target *ti, unsigned num_bios,

				unsigned *len)

				struct dm_target *ti, unsigned num_bios)

{

	struct bio *bio;

	int try;
@@ -1335,7 +1334,7 @@ static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci, 
		if (try)

			mutex_lock(&ci->io->md->table_devices_lock);

		for (bio_nr = 0; bio_nr < num_bios; bio_nr++) {

			bio = alloc_tio(ci, ti, bio_nr, len,

			bio = alloc_tio(ci, ti, bio_nr, NULL,

					try ? GFP_NOIO : GFP_NOWAIT);

			if (!bio)

				break;
@@ -1363,11 +1362,11 @@ static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti, 
		break;

	case 1:

		clone = alloc_tio(ci, ti, 0, len, GFP_NOIO);

		dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO);

		__map_bio(clone);

		break;

	default:

		alloc_multiple_bios(&blist, ci, ti, num_bios, len);

		/* dm_accept_partial_bio() is not supported with shared tio->len_ptr */

		alloc_multiple_bios(&blist, ci, ti, num_bios);

		while ((clone = bio_list_pop(&blist))) {

			dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO);

			__map_bio(clone);
@@ -1407,14 +1406,10 @@ static void __send_changing_extent_only(struct clone_info *ci, struct dm_target 
	len = min_t(sector_t, ci->sector_count,

		    max_io_len_target_boundary(ti, dm_target_offset(ti, ci->sector)));



	/*

	 * dm_accept_partial_bio cannot be used with duplicate bios,

	 * so update clone_info cursor before __send_duplicate_bios().

	 */

	__send_duplicate_bios(ci, ti, num_bios, &len);



	ci->sector += len;

	ci->sector_count -= len;



	__send_duplicate_bios(ci, ti, num_bios, &len);

}



static bool is_abnormal_io(struct bio *bio)