[PATCH 5.13 070/266] dm: Fix dm_accept_partial_bio() relative to zone management commands

Greg Kroah-Hartman
2021-07-15T19:29:02Z

From: Damien Le Moal <damien.lemoal@wdc.com>

[ Upstream commit 6842d264aa5205da338b6dcc6acfa2a6732558f1 ]

Fix dm_accept_partial_bio() to actually check that zone management
commands are not passed as explained in the function documentation
comment. Also, since a zone append operation cannot be split, add
REQ_OP_ZONE_APPEND as a forbidden command.

White lines are added around the group of BUG_ON() calls to make the
code more legible.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ca2aedd8ee7d..11af20080639 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1237,8 +1237,8 @@ static int dm_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,

/*
* A target may call dm_accept_partial_bio only from the map routine. It is
- * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_RESET,
- * REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE and REQ_OP_ZONE_FINISH.
+ * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_* zone management
+ * operations and REQ_OP_ZONE_APPEND (zone append writes).
*
* dm_accept_partial_bio informs the dm that the target only wants to process
* additional n_sectors sectors of the bio and the rest of the data should be
@@ -1268,9 +1268,13 @@ void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors)
{
struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
unsigned bi_size = bio->bi_iter.bi_size >> SECTOR_SHIFT;
+
BUG_ON(bio->bi_opf & REQ_PREFLUSH);
+ BUG_ON(op_is_zone_mgmt(bio_op(bio)));
+ BUG_ON(bio_op(bio) == REQ_OP_ZONE_APPEND);
BUG_ON(bi_size > *tio->len_ptr);
BUG_ON(n_sectors > bi_size);
+
*tio->len_ptr -= bi_size - n_sectors;
bio->bi_iter.bi_size = n_sectors << SECTOR_SHIFT;
}
--
2.30.2