Commit Graph

140 Commits

Author SHA1 Message Date
Philipp Reisner
77e8fdfc18 drbd: Only print sanitize state's warnings, if the state change happens
The reason for this change is that, with when doing
'drbdadm invalidate' on a disconnected resource caused
an "implicitly set pdsk from UpToDate to DUnknown" message,
which was missleading.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2012-05-09 10:08:22 +02:00
Lars Ellenberg
07667347c8 drbd: downgraded error printk to info
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2012-05-09 10:05:25 +02:00
Rusty Russell
90ab5ee941 module_param: make bool parameters really bool (drivers & misc)
module_param(bool) used to counter-intuitively take an int.  In
fddd5201 (mid-2009) we allowed bool or int/unsigned int using a messy
trick.

It's time to remove the int/unsigned int option.  For this version
it'll simply give a warning, but it'll break next kernel version.

Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-13 09:32:20 +10:30
Bart Van Assche
24c4830c8e drbd: Fix spelling
Found these with the help of ispell -l.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
2011-05-24 10:21:29 +02:00
Philipp Reisner
99432fcc52 drbd: Take a more conservative approach when deciding max_bio_size
The old (optimistic) implementation could shrink the bio size
on an primary device.

Shrinking the bio size on a primary device is bad. Since there
we might get BIOs with the old (bigger) size shortly after
we published the new size.

The new implementation is more conservative, and eventually
increases the max_bio_size on a primary device (which is valid).
It does so, when it knows the local limit AND the remote limit.

 We cache the last seen max_bio_size of the peer in the meta
 data, and rely on that, to make the operation of single
 nodes more efficient.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-05-24 10:08:58 +02:00
Philipp Reisner
fa7d939663 drbd: Disallow the peer_disk_state to be D_OUTDATED while connected
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-05-24 10:07:50 +02:00
Philipp Reisner
738a84b25c drbd: Fix for application IO with the on-io-error=pass-on policy
In case a write failes on the local disk, go into D_INCONSISTENT
disk state. That causes future reads of that block to be shipped
to the peer.

Read retry remote was already in place.

Actually the documentation needs to get fixed now. Since the
application is still shielded from the error. (as long as we have
only a single disk failing) The difference to detach is that
we keep the disk. And therefore might keep all the other, still
working sectors up to date.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-05-24 09:59:49 +02:00
Lucas De Marchi
25985edced Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 11:26:23 -03:00
Philipp Reisner
7fde2be930 drbd: Implemented real timeout checking for request processing time
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:48:16 +01:00
Lars Ellenberg
e636db5b95 drbd: fix potential imbalance of ap_in_flight
When we receive a barrier ack, we walk the ring list of drbd requests
in the transfer log of the respective epoch, do some housekeeping,
and free those objects.

We tried to keep epochs of mirrored and unmirrored drbd requests
separate, and assert that no local-only requests are present in a
barrier_acked epoch.

It turns out that this has quite a number of corner cases and would
add bloated code without functional benefit.

We now revert the (insufficient) commits
 drbd: Fixed an issue with AHEAD -> SYNC_SOURCE transitions
 drbd: Ensure that an epoch contains only requests of one kind
and instead fix the processing of barrier acks to cope with
a mix of local-only and mirrored requests.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:48:06 +01:00
Lars Ellenberg
0ddc5549f8 drbd: silence some noisy log messages during disconnect
If we fail to send the information that we lost our disk,
we have no connection, and no disk: no access to data anymore.
That is either expected (deconfiguration), or there will be so much
noise in the logs that "Sending state failed" is not useful at all.
Drop it.

If the reason for a shorter than expected receive was a signal,
which we sent because we already decided to disconnect,
these additional log messages are confusing and useless.

This patch follows this pattern:
 - dev_warn(DEV, "short read expecting header on sock: r=%d\n", r);
 + if (!signal_pending(current))
 + 	dev_warn(DEV, "short read expecting header on sock: r=%d\n", r);

Also make them all dev_warn for consistency.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:48:04 +01:00
Lars Ellenberg
20ceb2b22e drbd: describe bitmap locking for bulk operation in finer detail
Now that we do no longer in-place endian-swap the bitmap, we allow
selected bitmap operations (testing bits, sometimes even settting bits)
during some bulk operations.

This caused us to hit a lot of FIXME asserts similar to
	FIXME asender in drbd_bm_count_bits,
	bitmap locked for 'write from resync_finished' by worker
Which now is nonsense: looking at the bitmap is perfectly legal
as long as it is not being resized.

This cosmetic patch defines some flags to describe expectations in finer
detail, so the asserts in e.g. bm_change_bits_to() can be skipped if
appropriate.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:48:02 +01:00
Lars Ellenberg
62b0da3a24 drbd: log UUIDs whenever they change
All decisions about sync, sync direction, and wether or not to
allow a connect or attach are based on our set of UUIDs to tag a
data generation.

Log changes to the UUIDs whenever they occur,
logging "new current UUID P:Q:R:S" is more useful
than "Creating new current UUID".

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:48:01 +01:00
Lars Ellenberg
79a30d2d71 drbd: queue bitmap writeout more intelligently
The "lazy writeout" of cleared bitmap pages happens during resync, and
should happen again once the resync finishes cleanly, or is aborted.

If resync finished cleanly, or was aborted because of peer disk
failure, we trigger the writeout from worker context in the after
state change work.

If resync was aborted because of connection failure, we should not
immediately trigger bitmap writeout, but rather postpone the
writeout to after the connection cleanup happened.  We now do it
in the receiver context from drbd_disconnect().

If resync was aborted because of local disk failure, well, there
is nothing to write to anymore.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:47:56 +01:00
Lars Ellenberg
54b956abef drbd: don't pointlessly queue bitmap send, if we lost connection
This is a minor optimization and cleanup,
and also considerably reduces some harmless (but noisy) race with
the connection cleanup code.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:47:55 +01:00
Philipp Reisner
6a35c45f89 drbd: Ensure that an epoch contains only requests of one kind
The assert in drbd_req.c:755 forces us to have only requests of
one kind in an epoch. The two kinds we distinguish here are:
local-only or mirrored.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:42 +01:00
Philipp Reisner
148efa165e drbd: Do not drop net config if sending in drbd_send_protocol() fails
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:37 +01:00
Philipp Reisner
370a43e798 drbd: Work on the Ahead -> SyncSource transition
The test if rs_pending_cnt == 0 was too weak. Using Test for
unacked_cnt == 0 instead. Moved that into the worker.

Since unacked_cnt gets already increased when an P_RS_DATA_REQ
comes in.

Also using a timer to make Ahead -> SyncSource -> Ahead cycles
slower...

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:36 +01:00
Philipp Reisner
4a23f26496 drbd: Do not full sync if a P_SYNC_UUID packet gets lost
See also commit from 2009-08-15
"drbd_uuid_compare(): Do not full sync in case a P_SYNC_UUID packet gets lost."

We saw cases where the History UUIDs where not as expected. So the
detection of the special case did not trigger. With the sync UUID
no longer being a random number, but deducible from the previous
bitmap UUID, the detection of this special case becomes more
reliable.

The SyncUUID now is the previous bitmap UUID + 0x1000000000000.

Rule 5a:
Cs = H1p & H1p + Offset = Bp
  Connection was lost before SyncUUID Packet came through.
  Corrent (peer) UUIDs:
   Bp = H1p
   H1p = H2p
   H2p = 0
  Become Sync target.

Rule 7a:
Cp = H1s & H1s + Offset = Bs
  Connection was lost before SyncUUID Packet came through.
  Correct (own) UUIDs:
   Bs = H1s
   H1s = H2s
   H2s = 0
  Become Sync source.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:32 +01:00
Philipp Reisner
2b8a90b555 drbd: Corrected off-by-one error in DRBD_MINOR_COUNT_MAX
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:31 +01:00
Philipp Reisner
794abb753e drbd: Cleaned up the resync timer logic
Besides removed a few lines of code, this moves the inspection
of the state from before the queuing process to after the queuing.
I.e. more closely to the actual invocation of the work.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:28 +01:00
Philipp Reisner
617049aa7d drbd: Fixed an issue with AHEAD -> SYNC_SOURCE transitions
Create a new barrier when leaving the AHEAD mode.

  Otherwise we trigger the assertion in req_mod(, barrier_acked)
  D_ASSERT(req->rq_state & RQ_NET_SENT);

The new barrier is created by recycling the newest existing one.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:23 +01:00
Philipp Reisner
3f98688afc drbd: There might be a resync after unfreezing IO due to no disk [Bugz 332]
When on-no-data-accessible is set to suspend-io, also consider that
a Primary, SyncTarget node losses its connection.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:45:20 +01:00
Lars Ellenberg
06d33e968d drbd: improve on bitmap write out timing
Even though we now track the need for bitmap writeout per bitmap page,
there is no need to trigger the writeout while a resync is going on.

Once the resync is finished (or aborted),
we trigger bitmap writeout anyways.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:43:40 +01:00
Lars Ellenberg
418e0a927d drbd: spelling fix in log message
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:43:38 +01:00
Lars Ellenberg
5a22db8968 drbd: serialize sending of resync uuid with pending w_send_oos
To improve the latency of IO requests during bitmap exchange,
we recently allowed writes while waiting for the bitmap, sending "set
out-of-sync" information packets for any newly dirtied bits.

We have to make sure that the new resync-uuid does not overtake
these "set oos" packets. Once the resync-uuid is received, the
sync target starts the resync process, and expects the bitmap to
only be cleared, not re-set.

If we use this protocol extension, we queue the generation and sending
of the resync-uuid on the worker, which naturally serializes with all
previously queued packets.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:43:35 +01:00
Lars Ellenberg
2265b473ae drbd: fix potential dereference of NULL pointer
If drbd used to have crypto digest algorithms configured, then is being
unconfigured (but not unloaded), it frees the algorithms, but does not
reset the config.  If it then is reconfigured to use the very same
algorithm, it "forgot" to re-allocate the algorithms, thinking that the
config has not changed in that aspect.
It will then Oops on the first attempt to actually use those algorithms.

Fix this by resetting the config to defaults after cleanup.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:43:30 +01:00
Lars Ellenberg
02851e9f00 drbd: move bitmap write from resync_finished to after_state_change
We must not call it directly from resync_finished,
as we may be in either receiver or worker context there.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:43:29 +01:00
Lars Ellenberg
19f843aa08 drbd: bitmap keep track of changes vs on-disk bitmap
When we set or clear bits in a bitmap page,
also set a flag in the page->private pointer.

This allows us to skip writes of unchanged pages.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:43:19 +01:00
Andreas Gruenbacher
1b881ef775 drbd: Rename __inc_ap_bio_cond to may_inc_ap_bio
The old name is confusing: the function does not increment anything.
Also rename _inc_ap_bio_cond to inc_ap_bio_cond: there is no need for
an underscore.
Finally, make it clear that these functions return boolean values.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:37 +01:00
Andreas Gruenbacher
f70af118e3 drbd: send_bitmap_rle_or_plain: Get rid of ugly and useless enum
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:32 +01:00
Andreas Gruenbacher
81e84650c2 drbd: Use the standard bool, true, and false keywords
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:24 +01:00
Andreas Gruenbacher
bf885f8a67 drbd: Be more explicit about functions that return an enum drbd_state_rv
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:19 +01:00
Andreas Gruenbacher
c8b325632f drbd: Rename enum drbd_state_ret_codes to enum drbd_state_rv
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:18 +01:00
Andreas Gruenbacher
116676ca62 drbd: Rename enum drbd_ret_codes to enum drbd_ret_code
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:16 +01:00
Andreas Gruenbacher
662d91a23a drbd: Get rid of unnecessary macros (1)
This macro doesn't save much code, but makes things a lot harder to read.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:13 +01:00
Andreas Gruenbacher
2f58dcfc85 drbd: Rename drbd_make_request_26 to drbd_make_request
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:36:11 +01:00
Andreas Gruenbacher
cab2f74b45 drbd: Make sure that drbd_send() has sent the right number of bytes
Reviewed-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
2011-03-10 11:36:08 +01:00
Lars Ellenberg
17a93f3007 drbd: remove /proc/drbd before unregistering from netlink
There still exists a (theoretical) race on module unload, where
/proc/drbd may still exist, but the netlink callback has been
unregistered already, allowing drbdsetup to shout without listeners,
and get no reply.

Reorder remove_proc_entry and unregister of netlink callback.
drbdsetup first checks for existence of the proc entry,
and if that is missing, won't even try to contact the module.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:35:12 +01:00
Philipp Reisner
1fc80cf378 drbd: Becoming sync target may not happen out of < C_WF_REPORT_PARAMS
This patch is acutally a necessary addendum to the patch
"fix for spurious full sync (becoming sync target looked like invalidate)"

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:35:07 +01:00
Philipp Reisner
3719094ec2 drbd: Starting with protocol 96 we can allow app-IO while receiving the bitmap
* C_STARTING_SYNC_S, C_STARTING_SYNC_T In these states the bitmap gets
  written to disk. Locking out of app-IO is done by using the
  drbd_queue_bitmap_io() and drbd_bitmap_io() functions these days.
  It is no longer necessary to lock out app-IO based on the connection
  state.
  App-IO that may come in after the BITMAP_IO flag got cleared before the
  state transition to C_SYNC_(SOURCE|TARGET) does not get mirrored, sets
  a bit in the local bitmap, that is already set, therefore changes nothing.

* C_WF_BITMAP_S In this state we send updates (P_OUT_OF_SYNC packets).
  With that we make sure they have the same number of bits when going
  into the C_SYNC_(SOURCE|TARGET) connection state.

* C_UNCONNECTED: The receiver starts, no need to lock out IO.

* C_DISCONNECTING: in drbd_disconnect() we had a wait_event()
  to wait until ap_bio_cnt reaches 0. Removed that.

* C_TIMEOUT, C_BROKEN_PIPE, C_NETWORK_FAILURE
  C_PROTOCOL_ERROR, C_TEAR_DOWN: Same as C_DISCONNECTING

* C_WF_REPORT_PARAMS: IO still possible since that is still
  like C_WF_CONNECTION.

And we do not need to send barriers in C_WF_BITMAP_S connection state.

Allow concurrent accesses to the bitmap when receiving the bitmap.
Everything gets ORed anyways.

A drbd_free_tl_hash() is in after_state_chg_work(). At that point
all the work items of the last connections must have been processed.

Introduced a call to drbd_free_tl_hash() into drbd_free_mdev()
for paranoia reasons.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:35:06 +01:00
Philipp Reisner
ab17b68f45 drbd: Improvements in sanitize_state()
The relevant change is that the state change to C_FW_BITMAP_S should
implicitly change pdsk to C_CONSISTENT. (Think of it as C_OUTDATED, only
without the guarantee that the peer has the outdated written to its
meta data)

At that opportunity I restructured the switch statement so that it
gets evaluated every time. (Has declarative character)

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:35:04 +01:00
Philipp Reisner
22afd7ee94 drbd: Fixed race condition in drbd_queue_bitmap_io
May only test for ap_bio_cnt == 0 under req_lock. It can increase
only under req_lock.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:35:03 +01:00
Philipp Reisner
127b317844 drbd: use test_and_set_bit() to decide if bm_io_work should be queued
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:34:59 +01:00
Philipp Reisner
c4752ef128 drbd: When proxy's buffer drained off go into regular resync mode
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:34:49 +01:00
Philipp Reisner
73a01a18b9 drbd: New packet for Ahead/Behind mode: P_OUT_OF_SYNC
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:34:48 +01:00
Philipp Reisner
67531718d8 drbd: Implemented two new connection states Ahead/Behind
In this connection mode, the ahead node no longer replicates
application IO. The behind's disk becomes out dated.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:34:46 +01:00
Philipp Reisner
759fbdfba6 drbd: Track the numbers of sectors in flight
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:34:43 +01:00
Lars Ellenberg
1816a2b47a drbd: properly use max_hw_sectors to limit the our bio size
To ease tracking of bios in some hash tables, we want it to
not cross certain boundaries (128k, used to be 32k).
We limit the maximum bio size using queue parameters.

Historically some defines and variables we use there have been named
max_segment_size, which was misguided. Rename them to max_bio_size,
and use [blk_]queue_max_hw_sectors where appropriate.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
2011-03-10 11:19:11 +01:00
Lars Ellenberg
470be44ab1 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>
2011-03-10 11:19:08 +01:00