[dm-devel] [PATCH v4 04/11] dm: Fix dm_accept_partial_bio()

[Damien Le Moal]

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 at wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn at wdc.com>
Reviewed-by: Hannes Reinecke <hare at suse.de>
---
 drivers/md/dm.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ca2aedd8ee7d..a9211575bfed 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1237,8 +1237,9 @@ 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, zone management operations
+ * (REQ_OP_ZONE_RESET, REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE and
+ * REQ_OP_ZONE_FINISH) and 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 +1269,13 @@ 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;
 }
-- 
2.31.1