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authorIlya Dryomov <ilya.dryomov@inktank.com>2014-06-10 13:53:29 +0400
committerIlya Dryomov <ilya.dryomov@inktank.com>2014-06-23 12:55:37 +0400
commit9638556a276125553549fdfe349c464481ec2f39 (patch)
treead8df9f63ce194d773efaa362b08d4e1177cb690
parenta497c3ba1d97fc69c1e78e7b96435ba8c2cb42ee (diff)
rbd: handle parent_overlap on writes correctly
The following check in rbd_img_obj_request_submit() rbd_dev->parent_overlap <= obj_request->img_offset allows the fall through to the non-layered write case even if both parent_overlap and obj_request->img_offset belong to the same RADOS object. This leads to data corruption, because the area to the left of parent_overlap ends up unconditionally zero-filled instead of being populated with parent data. Suppose we want to write 1M to offset 6M of image bar, which is a clone of foo@snap; object_size is 4M, parent_overlap is 5M: rbd_data.<id>.0000000000000001 ---------------------|----------------------|------------ | should be copyup'ed | should be zeroed out | write ... ---------------------|----------------------|------------ 4M 5M 6M parent_overlap obj_request->img_offset 4..5M should be copyup'ed from foo, yet it is zero-filled, just like 5..6M is. Given that the only striping mode kernel client currently supports is chunking (i.e. stripe_unit == object_size, stripe_count == 1), round parent_overlap up to the next object boundary for the purposes of the overlap check. Cc: stable@vger.kernel.org # 3.10+ Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
-rw-r--r--drivers/block/rbd.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index bbeb404b3a0..b2c98c1bc03 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1431,6 +1431,14 @@ static bool obj_request_exists_test(struct rbd_obj_request *obj_request)
return test_bit(OBJ_REQ_EXISTS, &obj_request->flags) != 0;
}
+static bool obj_request_overlaps_parent(struct rbd_obj_request *obj_request)
+{
+ struct rbd_device *rbd_dev = obj_request->img_request->rbd_dev;
+
+ return obj_request->img_offset <
+ round_up(rbd_dev->parent_overlap, rbd_obj_bytes(&rbd_dev->header));
+}
+
static void rbd_obj_request_get(struct rbd_obj_request *obj_request)
{
dout("%s: obj %p (was %d)\n", __func__, obj_request,
@@ -2748,7 +2756,7 @@ static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
*/
if (!img_request_write_test(img_request) ||
!img_request_layered_test(img_request) ||
- rbd_dev->parent_overlap <= obj_request->img_offset ||
+ !obj_request_overlaps_parent(obj_request) ||
((known = obj_request_known_test(obj_request)) &&
obj_request_exists_test(obj_request))) {