in drbd/drbd_receiver.c [3269:3482]
static int drbd_uuid_compare(struct drbd_device *const device, enum drbd_role const peer_role, int *rule_nr) __must_hold(local)
{
struct drbd_peer_device *const peer_device = first_peer_device(device);
struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL;
u64 self, peer;
int i, j;
self = device->ldev->md.uuid[UI_CURRENT] & ~((u64)1);
peer = device->p_uuid[UI_CURRENT] & ~((u64)1);
*rule_nr = 10;
if (self == UUID_JUST_CREATED && peer == UUID_JUST_CREATED)
return 0;
*rule_nr = 20;
if ((self == UUID_JUST_CREATED || self == (u64)0) &&
peer != UUID_JUST_CREATED)
return -2;
*rule_nr = 30;
if (self != UUID_JUST_CREATED &&
(peer == UUID_JUST_CREATED || peer == (u64)0))
return 2;
if (self == peer) {
int rct, dc; /* roles at crash time */
if (device->p_uuid[UI_BITMAP] == (u64)0 && device->ldev->md.uuid[UI_BITMAP] != (u64)0) {
if (connection->agreed_pro_version < 91)
return -1091;
if ((device->ldev->md.uuid[UI_BITMAP] & ~((u64)1)) == (device->p_uuid[UI_HISTORY_START] & ~((u64)1)) &&
(device->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1)) == (device->p_uuid[UI_HISTORY_START + 1] & ~((u64)1))) {
drbd_info(device, "was SyncSource, missed the resync finished event, corrected myself:\n");
drbd_uuid_move_history(device);
device->ldev->md.uuid[UI_HISTORY_START] = device->ldev->md.uuid[UI_BITMAP];
device->ldev->md.uuid[UI_BITMAP] = 0;
drbd_uuid_dump(device, "self", device->ldev->md.uuid,
device->state.disk >= D_NEGOTIATING ? drbd_bm_total_weight(device) : 0, 0);
*rule_nr = 34;
} else {
drbd_info(device, "was SyncSource (peer failed to write sync_uuid)\n");
*rule_nr = 36;
}
return 1;
}
if (device->ldev->md.uuid[UI_BITMAP] == (u64)0 && device->p_uuid[UI_BITMAP] != (u64)0) {
if (connection->agreed_pro_version < 91)
return -1091;
if ((device->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1)) == (device->p_uuid[UI_BITMAP] & ~((u64)1)) &&
(device->ldev->md.uuid[UI_HISTORY_START + 1] & ~((u64)1)) == (device->p_uuid[UI_HISTORY_START] & ~((u64)1))) {
drbd_info(device, "was SyncTarget, peer missed the resync finished event, corrected peer:\n");
device->p_uuid[UI_HISTORY_START + 1] = device->p_uuid[UI_HISTORY_START];
device->p_uuid[UI_HISTORY_START] = device->p_uuid[UI_BITMAP];
device->p_uuid[UI_BITMAP] = 0UL;
drbd_uuid_dump(device, "peer", device->p_uuid, device->p_uuid[UI_SIZE], device->p_uuid[UI_FLAGS]);
*rule_nr = 35;
} else {
drbd_info(device, "was SyncTarget (failed to write sync_uuid)\n");
*rule_nr = 37;
}
return -1;
}
/* Common power [off|failure] */
rct = (test_bit(CRASHED_PRIMARY, &device->flags) ? 1 : 0) +
(device->p_uuid[UI_FLAGS] & 2);
/* lowest bit is set when we were primary,
* next bit (weight 2) is set when peer was primary */
*rule_nr = 40;
/* Neither has the "crashed primary" flag set,
* only a replication link hickup. */
if (rct == 0)
return 0;
/* Current UUID equal and no bitmap uuid; does not necessarily
* mean this was a "simultaneous hard crash", maybe IO was
* frozen, so no UUID-bump happened.
* This is a protocol change, overload DRBD_FF_WSAME as flag
* for "new-enough" peer DRBD version. */
if (device->state.role == R_PRIMARY || peer_role == R_PRIMARY) {
*rule_nr = 41;
if (!(connection->agreed_features & DRBD_FF_WSAME)) {
drbd_warn(peer_device, "Equivalent unrotated UUIDs, but current primary present.\n");
return -(0x10000 | PRO_VERSION_MAX | (DRBD_FF_WSAME << 8));
}
if (device->state.role == R_PRIMARY && peer_role == R_PRIMARY) {
/* At least one has the "crashed primary" bit set,
* both are primary now, but neither has rotated its UUIDs?
* "Can not happen." */
drbd_err(peer_device, "Equivalent unrotated UUIDs, but both are primary. Can not resolve this.\n");
return -100;
}
if (device->state.role == R_PRIMARY)
return 1;
return -1;
}
/* Both are secondary.
* Really looks like recovery from simultaneous hard crash.
* Check which had been primary before, and arbitrate. */
switch (rct) {
case 0: /* !self_pri && !peer_pri */ return 0; /* already handled */
case 1: /* self_pri && !peer_pri */ return 1;
case 2: /* !self_pri && peer_pri */ return -1;
case 3: /* self_pri && peer_pri */
dc = test_bit(RESOLVE_CONFLICTS, &connection->flags);
return dc ? -1 : 1;
}
}
*rule_nr = 50;
peer = device->p_uuid[UI_BITMAP] & ~((u64)1);
if (self == peer)
return -1;
*rule_nr = 51;
peer = device->p_uuid[UI_HISTORY_START] & ~((u64)1);
if (self == peer) {
if (connection->agreed_pro_version < 96 ?
(device->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1)) ==
(device->p_uuid[UI_HISTORY_START + 1] & ~((u64)1)) :
peer + UUID_NEW_BM_OFFSET == (device->p_uuid[UI_BITMAP] & ~((u64)1))) {
/* The last P_SYNC_UUID did not get though. Undo the last start of
resync as sync source modifications of the peer's UUIDs. */
if (connection->agreed_pro_version < 91)
return -1091;
device->p_uuid[UI_BITMAP] = device->p_uuid[UI_HISTORY_START];
device->p_uuid[UI_HISTORY_START] = device->p_uuid[UI_HISTORY_START + 1];
drbd_info(device, "Lost last syncUUID packet, corrected:\n");
drbd_uuid_dump(device, "peer", device->p_uuid, device->p_uuid[UI_SIZE], device->p_uuid[UI_FLAGS]);
return -1;
}
}
*rule_nr = 60;
self = device->ldev->md.uuid[UI_CURRENT] & ~((u64)1);
for (i = UI_HISTORY_START; i <= UI_HISTORY_END; i++) {
peer = device->p_uuid[i] & ~((u64)1);
if (self == peer)
return -2;
}
*rule_nr = 70;
self = device->ldev->md.uuid[UI_BITMAP] & ~((u64)1);
peer = device->p_uuid[UI_CURRENT] & ~((u64)1);
if (self == peer)
return 1;
*rule_nr = 71;
self = device->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1);
if (self == peer) {
if (connection->agreed_pro_version < 96 ?
(device->ldev->md.uuid[UI_HISTORY_START + 1] & ~((u64)1)) ==
(device->p_uuid[UI_HISTORY_START] & ~((u64)1)) :
self + UUID_NEW_BM_OFFSET == (device->ldev->md.uuid[UI_BITMAP] & ~((u64)1))) {
/* The last P_SYNC_UUID did not get though. Undo the last start of
resync as sync source modifications of our UUIDs. */
if (connection->agreed_pro_version < 91)
return -1091;
__drbd_uuid_set(device, UI_BITMAP, device->ldev->md.uuid[UI_HISTORY_START]);
__drbd_uuid_set(device, UI_HISTORY_START, device->ldev->md.uuid[UI_HISTORY_START + 1]);
drbd_info(device, "Last syncUUID did not get through, corrected:\n");
drbd_uuid_dump(device, "self", device->ldev->md.uuid,
device->state.disk >= D_NEGOTIATING ? drbd_bm_total_weight(device) : 0, 0);
return 1;
}
}
*rule_nr = 80;
peer = device->p_uuid[UI_CURRENT] & ~((u64)1);
for (i = UI_HISTORY_START; i <= UI_HISTORY_END; i++) {
self = device->ldev->md.uuid[i] & ~((u64)1);
if (self == peer)
return 2;
}
*rule_nr = 90;
self = device->ldev->md.uuid[UI_BITMAP] & ~((u64)1);
peer = device->p_uuid[UI_BITMAP] & ~((u64)1);
if (self == peer && self != ((u64)0))
return 100;
*rule_nr = 100;
for (i = UI_HISTORY_START; i <= UI_HISTORY_END; i++) {
self = device->ldev->md.uuid[i] & ~((u64)1);
for (j = UI_HISTORY_START; j <= UI_HISTORY_END; j++) {
peer = device->p_uuid[j] & ~((u64)1);
if (self == peer)
return -100;
}
}
return -1000;
}