From: Mikulas Patocka mpatocka@redhat.com
stable inclusion from linux-4.19.193 commit 3fe7be3c1d77af7038ebb3d4972b00ebea5f8183
--------------------------------
commit 7e768532b2396bcb7fbf6f82384b85c0f1d2f197 upstream.
If an origin target has no snapshots, o->split_boundary is set to 0. This causes BUG_ON(sectors <= 0) in block/bio.c:bio_split().
Fix this by initializing chunk_size, and in turn split_boundary, to rounddown_pow_of_two(UINT_MAX) -- the largest power of two that fits into "unsigned" type.
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/md/dm-snap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 7d96836294713..52101e5c72588 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -794,7 +794,7 @@ static int dm_add_exception(void *context, chunk_t old, chunk_t new) static uint32_t __minimum_chunk_size(struct origin *o) { struct dm_snapshot *snap; - unsigned chunk_size = 0; + unsigned chunk_size = rounddown_pow_of_two(UINT_MAX);
if (o) list_for_each_entry(snap, &o->snapshots, list)