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>
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>
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>
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>
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>
When the sync source node replies to a P_RS_DATA_REQUEST packet
when it is already in ahead mode. I.e. those two packets
crossed each other on the wire, that may lead to diverging
bitmaps.
This never happens in a well-tuned-system. In a well-tuned-
system the resync controller has reduced the resync speed
to zero long before we got into ahead-mode.
But we have to be prepared for the not-well-tuned-system
of course as well.
Because -> diverging bitmaps = non terminating resync.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
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>
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>
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>
* 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>
The condition must be checked after perpare_to_wait(). The old
implementaion could loose wakeup events. Never observed in real
life.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
We only issue resync requests if there is no significant application IO
going on. = Application IO has higher priority than resnyc IO.
If application IO can not be started because the resync process locked
an resync_lru entry, start the IO operations necessary to release the
lock ASAP.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
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>
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>
Lars Ellenberg
Philipp Reisner
Andreas Gruenbacher