drbd: fix potential data corruption and protocol error
We assumed only bios with bi_idx == 0 would end up
in drbd_make_request().
That is wrong.
At least device mapper, in __clone_and_map(), may submit
clones only covering a partial bio, but sharing
the original bvec, by adjusting bi_idx and relevant
other bio members of the clone.
We used __bio_for_each_segment() in various places,
even though that is documented as
* drivers should not use the __ version unless they _really_ want to
* run through the entire bio and not just pending pieces
Impact: we would send the full bio bvec, even for the clone
with bi_idx > 0, which will cause data corruption on the
peer (because we submit wrong data at the clone offset),
and will cause a DRBD protocol error, disconnect/reconnect
and resync (thus fixing the corruption),
because the next package header would be expected right
in the middle of the sent data, causing DRBD magic mismatch.
Fix: drop the assert, and use bio_for_each_segment()
instead of the __ version.
Conflicts:
drbd/drbd_tracing.c
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 8ca8925..f6cfc45 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2734,7 +2734,7 @@
struct bio_vec *bvec;
int i;
/* hint all but last page with MSG_MORE */
- __bio_for_each_segment(bvec, bio, i, 0) {
+ bio_for_each_segment(bvec, bio, i) {
if (!_drbd_no_send_page(mdev, bvec->bv_page,
bvec->bv_offset, bvec->bv_len,
i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
@@ -2748,7 +2748,7 @@
struct bio_vec *bvec;
int i;
/* hint all but last page with MSG_MORE */
- __bio_for_each_segment(bvec, bio, i, 0) {
+ bio_for_each_segment(bvec, bio, i) {
if (!_drbd_send_page(mdev, bvec->bv_page,
bvec->bv_offset, bvec->bv_len,
i == bio->bi_vcnt -1 ? 0 : MSG_MORE))