From: Mikulas Patocka mpatocka@redhat.com
commit 7ee06ddc4038f936b0d4459d37a7d4d844fb03db 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.
Reported-by: Michael Tokarev mjt@tls.msk.ru Tested-by: Michael Tokarev mjt@tls.msk.ru Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/dm-snap.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -854,12 +854,11 @@ static int dm_add_exception(void *contex 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) - chunk_size = min_not_zero(chunk_size, - snap->store->chunk_size); + chunk_size = min(chunk_size, snap->store->chunk_size);
return (uint32_t) chunk_size; }