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Commit 5037108a authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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dm: always allow one page in dm_merge_bvec 



Some callers assume they can always add at least one page to an empty bio,
so dm_merge_bvec should not return 0 in this case: we'll reject the I/O
later after the bio is submitted.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent d3a47e82

drivers/md/dm.c

+5 −4
Original line number Diff line number Diff line
@@ -837,10 +837,10 @@ static int dm_merge_bvec(struct request_queue *q, 
	struct dm_table *map = dm_get_table(md);

	struct dm_target *ti;

	sector_t max_sectors;

	int max_size;

	int max_size = 0;



	if (unlikely(!map))

		return 0;

		goto out;



	ti = dm_table_find_target(map, bvm->bi_sector);
@@ -861,14 +861,15 @@ static int dm_merge_bvec(struct request_queue *q, 
	if (max_size && ti->type->merge)

		max_size = ti->type->merge(ti, bvm, biovec, max_size);



	dm_table_put(map);



out:

	/*

	 * Always allow an entire first page

	 */

	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))

		max_size = biovec->bv_len;



	dm_table_put(map);



	return max_size;

}