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drbd: serialize sending of resync uuid with pending w_send_oos

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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>
This commit is contained in:
Lars Ellenberg 2010-12-17 21:14:23 +01:00 committed by Philipp Reisner
parent f735e36354
commit 5a22db8968
3 changed files with 34 additions and 17 deletions
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2
drivers/block/drbd/drbd_int.h
View File

@ -1204,7 +1204,7 @@ extern int drbd_send(struct drbd_conf *mdev, struct socket *sock,
extern int drbd_send_protocol(struct drbd_conf *mdev);
extern int drbd_send_uuids(struct drbd_conf *mdev);
extern int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev);
extern int drbd_send_sync_uuid(struct drbd_conf *mdev, u64 val);
extern int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev);
extern int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags flags);
extern int _drbd_send_state(struct drbd_conf *mdev);
extern int drbd_send_state(struct drbd_conf *mdev);

22
drivers/block/drbd/drbd_main.c
View File

@ -1387,6 +1387,17 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
spin_unlock_irq(&mdev->req_lock);
}
/* Became sync source. With protocol >= 96, we still need to send out
* the sync uuid now. Need to do that before any drbd_send_state, or
* the other side may go "paused sync" before receiving the sync uuids,
* which is unexpected. */
if ((os.conn != C_SYNC_SOURCE && os.conn != C_PAUSED_SYNC_S) &&
(ns.conn == C_SYNC_SOURCE || ns.conn == C_PAUSED_SYNC_S) &&
mdev->agreed_pro_version >= 96 && get_ldev(mdev)) {
drbd_gen_and_send_sync_uuid(mdev);
put_ldev(mdev);
}
/* Do not change the order of the if above and the two below... */
if (os.pdsk == D_DISKLESS && ns.pdsk > D_DISKLESS) { /* attach on the peer */
drbd_send_uuids(mdev);
@ -1980,12 +1991,17 @@ int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev)
return _drbd_send_uuids(mdev, 8);
}
int drbd_send_sync_uuid(struct drbd_conf *mdev, u64 val)
int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
{
struct p_rs_uuid p;
u64 uuid;
p.uuid = cpu_to_be64(val);
D_ASSERT(mdev->state.disk == D_UP_TO_DATE);
get_random_bytes(&uuid, sizeof(u64));
drbd_uuid_set(mdev, UI_BITMAP, uuid);
drbd_md_sync(mdev);
p.uuid = cpu_to_be64(uuid);
return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_SYNC_UUID,
(struct p_header80 *)&p, sizeof(p));

27
drivers/block/drbd/drbd_worker.c
View File

@ -1516,18 +1516,6 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
return;
}
if (side == C_SYNC_TARGET) {
mdev->bm_resync_fo = 0;
} else /* side == C_SYNC_SOURCE */ {
u64 uuid;
get_random_bytes(&uuid, sizeof(u64));
drbd_uuid_set(mdev, UI_BITMAP, uuid);
drbd_send_sync_uuid(mdev, uuid);
D_ASSERT(mdev->state.disk == D_UP_TO_DATE);
}
write_lock_irq(&global_state_lock);
ns = mdev->state;
@ -1565,7 +1553,19 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
_drbd_pause_after(mdev);
}
write_unlock_irq(&global_state_lock);
put_ldev(mdev);
if (side == C_SYNC_TARGET)
mdev->bm_resync_fo = 0;
/* Since protocol 96, we must serialize drbd_gen_and_send_sync_uuid
* with w_send_oos, or the sync target will get confused as to
* how much bits to resync. We cannot do that always, because for an
* empty resync and protocol < 95, we need to do it here, as we call
* drbd_resync_finished from here in that case.
* We drbd_gen_and_send_sync_uuid here for protocol < 96,
* and from after_state_ch otherwise. */
if (side == C_SYNC_SOURCE && mdev->agreed_pro_version < 96)
drbd_gen_and_send_sync_uuid(mdev);
if (r == SS_SUCCESS) {
dev_info(DEV, "Began resync as %s (will sync %lu KB [%lu bits set]).\n",
@ -1601,6 +1601,7 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
drbd_md_sync(mdev);
}
put_ldev(mdev);
drbd_state_unlock(mdev);
}