drbd: detect modification of in-flight buffers

With data-integrity digest enabled, double-check on the sending side
for modifications by upper layers of buffers under write back,
so we can tell it appart from corruption on the "wire".

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index d0e19a242af4..ca213c6e5f9d 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1281,7 +1281,8 @@ read_in_block(struct drbd_conf *mdev, u64 id, sector_t sector, int data_size) __
         if (dgs) {
                 drbd_csum_ee(mdev, mdev->integrity_r_tfm, e, dig_vv);
                 if (memcmp(dig_in, dig_vv, dgs)) {
-                        dev_err(DEV, "Digest integrity check FAILED.\n");
+                        dev_err(DEV, "Digest integrity check FAILED: %llus +%u\n",
+                                (unsigned long long)sector, data_size);
                         drbd_bcast_ee(mdev, "digest failed",
                                         dgs, dig_in, dig_vv, e);
                         drbd_free_ee(mdev, e);