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>

drivers/block/drbd/drbd_int.h

@@ -1240,11 +1240,11 @@ extern int _drbd_send_bitmap(struct drbd_conf *mdev);
 extern int drbd_send_sr_reply(struct drbd_conf *mdev, enum drbd_state_rv retcode);
 extern void drbd_free_bc(struct drbd_backing_dev *ldev);
 extern void drbd_mdev_cleanup(struct drbd_conf *mdev);
+void drbd_print_uuids(struct drbd_conf *mdev, const char *text);
 
 /* drbd_meta-data.c (still in drbd_main.c) */
 extern void drbd_md_sync(struct drbd_conf *mdev);
 extern int  drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev);
-/* maybe define them below as inline? */
 extern void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);
 extern void _drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);
 extern void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local);
@@ -2360,9 +2360,11 @@ static inline void dec_ap_bio(struct drbd_conf *mdev)
 	}
 }
 
-static inline void drbd_set_ed_uuid(struct drbd_conf *mdev, u64 val)
+static inline int drbd_set_ed_uuid(struct drbd_conf *mdev, u64 val)
 {
+	int changed = mdev->ed_uuid != val;
 	mdev->ed_uuid = val;
+	return changed;
 }
 
 static inline int seq_cmp(u32 a, u32 b)

drivers/block/drbd/drbd_main.c

@@ -1159,6 +1159,10 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
 		atomic_inc(&mdev->local_cnt);
 
 	mdev->state = ns;
+
+	if (os.disk == D_ATTACHING && ns.disk >= D_NEGOTIATING)
+		drbd_print_uuids(mdev, "attached to UUIDs");
+
 	wake_up(&mdev->misc_wait);
 	wake_up(&mdev->state_wait);
 
@@ -2035,6 +2039,24 @@ int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev)
 	return _drbd_send_uuids(mdev, 8);
 }
 
+void drbd_print_uuids(struct drbd_conf *mdev, const char *text)
+{
+	if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
+		u64 *uuid = mdev->ldev->md.uuid;
+		dev_info(DEV, "%s %016llX:%016llX:%016llX:%016llX\n",
+		     text,
+		     (unsigned long long)uuid[UI_CURRENT],
+		     (unsigned long long)uuid[UI_BITMAP],
+		     (unsigned long long)uuid[UI_HISTORY_START],
+		     (unsigned long long)uuid[UI_HISTORY_END]);
+		put_ldev(mdev);
+	} else {
+		dev_info(DEV, "%s effective data uuid: %016llX\n",
+				text,
+				(unsigned long long)mdev->ed_uuid);
+	}
+}
+
 int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
 {
 	struct p_rs_uuid p;
@@ -2044,6 +2066,7 @@ int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
 
 	uuid = mdev->ldev->md.uuid[UI_BITMAP] + UUID_NEW_BM_OFFSET;
 	drbd_uuid_set(mdev, UI_BITMAP, uuid);
+	drbd_print_uuids(mdev, "updated sync UUID");
 	drbd_md_sync(mdev);
 	p.uuid = cpu_to_be64(uuid);
 
@@ -3749,28 +3772,6 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 	return rv;
 }
 
-static void debug_drbd_uuid(struct drbd_conf *mdev, enum drbd_uuid_index index)
-{
-	static char *uuid_str[UI_EXTENDED_SIZE] = {
-		[UI_CURRENT] = "CURRENT",
-		[UI_BITMAP] = "BITMAP",
-		[UI_HISTORY_START] = "HISTORY_START",
-		[UI_HISTORY_END] = "HISTORY_END",
-		[UI_SIZE] = "SIZE",
-		[UI_FLAGS] = "FLAGS",
-	};
-
-	if (index >= UI_EXTENDED_SIZE) {
-		dev_warn(DEV, " uuid_index >= EXTENDED_SIZE\n");
-		return;
-	}
-
-	dynamic_dev_dbg(DEV, " uuid[%s] now %016llX\n",
-		 uuid_str[index],
-		 (unsigned long long)mdev->ldev->md.uuid[index]);
-}
-
-
 /**
  * drbd_md_mark_dirty() - Mark meta data super block as dirty
  * @mdev:	DRBD device.
@@ -3800,10 +3801,8 @@ static void drbd_uuid_move_history(struct drbd_conf *mdev) __must_hold(local)
 {
 	int i;
 
-	for (i = UI_HISTORY_START; i < UI_HISTORY_END; i++) {
+	for (i = UI_HISTORY_START; i < UI_HISTORY_END; i++)
 		mdev->ldev->md.uuid[i+1] = mdev->ldev->md.uuid[i];
-		debug_drbd_uuid(mdev, i+1);
-	}
 }
 
 void _drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
@@ -3818,7 +3817,6 @@ void _drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
 	}
 
 	mdev->ldev->md.uuid[idx] = val;
-	debug_drbd_uuid(mdev, idx);
 	drbd_md_mark_dirty(mdev);
 }
 
@@ -3828,7 +3826,6 @@ void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
 	if (mdev->ldev->md.uuid[idx]) {
 		drbd_uuid_move_history(mdev);
 		mdev->ldev->md.uuid[UI_HISTORY_START] = mdev->ldev->md.uuid[idx];
-		debug_drbd_uuid(mdev, UI_HISTORY_START);
 	}
 	_drbd_uuid_set(mdev, idx, val);
 }
@@ -3843,14 +3840,16 @@ void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
 void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local)
 {
 	u64 val;
+	unsigned long long bm_uuid = mdev->ldev->md.uuid[UI_BITMAP];
+
+	if (bm_uuid)
+		dev_warn(DEV, "bm UUID was already set: %llX\n", bm_uuid);
 
-	dev_info(DEV, "Creating new current UUID\n");
-	D_ASSERT(mdev->ldev->md.uuid[UI_BITMAP] == 0);
 	mdev->ldev->md.uuid[UI_BITMAP] = mdev->ldev->md.uuid[UI_CURRENT];
-	debug_drbd_uuid(mdev, UI_BITMAP);
 
 	get_random_bytes(&val, sizeof(u64));
 	_drbd_uuid_set(mdev, UI_CURRENT, val);
+	drbd_print_uuids(mdev, "new current UUID");
 	/* get it to stable storage _now_ */
 	drbd_md_sync(mdev);
 }
@@ -3864,16 +3863,12 @@ void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local)
 		drbd_uuid_move_history(mdev);
 		mdev->ldev->md.uuid[UI_HISTORY_START] = mdev->ldev->md.uuid[UI_BITMAP];
 		mdev->ldev->md.uuid[UI_BITMAP] = 0;
-		debug_drbd_uuid(mdev, UI_HISTORY_START);
-		debug_drbd_uuid(mdev, UI_BITMAP);
 	} else {
-		if (mdev->ldev->md.uuid[UI_BITMAP])
-			dev_warn(DEV, "bm UUID already set");
-
-		mdev->ldev->md.uuid[UI_BITMAP] = val;
-		mdev->ldev->md.uuid[UI_BITMAP] &= ~((u64)1);
+		unsigned long long bm_uuid = mdev->ldev->md.uuid[UI_BITMAP];
+		if (bm_uuid)
+			dev_warn(DEV, "bm UUID was already set: %llX\n", bm_uuid);
 
-		debug_drbd_uuid(mdev, UI_BITMAP);
+		mdev->ldev->md.uuid[UI_BITMAP] = val & ~((u64)1);
 	}
 	drbd_md_mark_dirty(mdev);
 }

drivers/block/drbd/drbd_nl.c

@@ -2151,6 +2151,7 @@ static int drbd_nl_new_c_uuid(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nl
 		if (skip_initial_sync) {
 			drbd_send_uuids_skip_initial_sync(mdev);
 			_drbd_uuid_set(mdev, UI_BITMAP, 0);
+			drbd_print_uuids(mdev, "cleared bitmap UUID");
 			spin_lock_irq(&mdev->req_lock);
 			_drbd_set_state(_NS2(mdev, disk, D_UP_TO_DATE, pdsk, D_UP_TO_DATE),
 					CS_VERBOSE, NULL);

drivers/block/drbd/drbd_receiver.c

@@ -3024,7 +3024,7 @@ static int receive_uuids(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 {
 	struct p_uuids *p = &mdev->data.rbuf.uuids;
 	u64 *p_uuid;
-	int i;
+	int i, updated_uuids = 0;
 
 	p_uuid = kmalloc(sizeof(u64)*UI_EXTENDED_SIZE, GFP_NOIO);
 
@@ -3059,13 +3059,14 @@ static int receive_uuids(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 			_drbd_set_state(_NS2(mdev, disk, D_UP_TO_DATE, pdsk, D_UP_TO_DATE),
 					CS_VERBOSE, NULL);
 			drbd_md_sync(mdev);
+			updated_uuids = 1;
 		}
 		put_ldev(mdev);
 	} else if (mdev->state.disk < D_INCONSISTENT &&
 		   mdev->state.role == R_PRIMARY) {
 		/* I am a diskless primary, the peer just created a new current UUID
 		   for me. */
-		drbd_set_ed_uuid(mdev, p_uuid[UI_CURRENT]);
+		updated_uuids = drbd_set_ed_uuid(mdev, p_uuid[UI_CURRENT]);
 	}
 
 	/* Before we test for the disk state, we should wait until an eventually
@@ -3074,7 +3075,10 @@ static int receive_uuids(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 	   new disk state... */
 	wait_event(mdev->misc_wait, !test_bit(CLUSTER_ST_CHANGE, &mdev->flags));
 	if (mdev->state.conn >= C_CONNECTED && mdev->state.disk < D_INCONSISTENT)
-		drbd_set_ed_uuid(mdev, p_uuid[UI_CURRENT]);
+		updated_uuids |= drbd_set_ed_uuid(mdev, p_uuid[UI_CURRENT]);
+
+	if (updated_uuids)
+		drbd_print_uuids(mdev, "receiver updated UUIDs to");
 
 	return true;
 }
@@ -3305,6 +3309,7 @@ static int receive_sync_uuid(struct drbd_conf *mdev, enum drbd_packets cmd, unsi
 		_drbd_uuid_set(mdev, UI_CURRENT, be64_to_cpu(p->uuid));
 		_drbd_uuid_set(mdev, UI_BITMAP, 0UL);
 
+		drbd_print_uuids(mdev, "updated sync uuid");
 		drbd_start_resync(mdev, C_SYNC_TARGET);
 
 		put_ldev(mdev);

drivers/block/drbd/drbd_worker.c

@@ -871,8 +871,11 @@ int drbd_resync_finished(struct drbd_conf *mdev)
 			}
 		}
 
+		if (!(os.conn == C_VERIFY_S || os.conn == C_VERIFY_T)) {
+			/* for verify runs, we don't update uuids here,
+			 * so there would be nothing to report. */
 			drbd_uuid_set_bm(mdev, 0UL);
-
+			drbd_print_uuids(mdev, "updated UUIDs");
 			if (mdev->p_uuid) {
 				/* Now the two UUID sets are equal, update what we
 				 * know of the peer. */
@@ -881,6 +884,7 @@ int drbd_resync_finished(struct drbd_conf *mdev)
 					mdev->p_uuid[i] = mdev->ldev->md.uuid[i];
 			}
 		}
+	}
 
 	_drbd_set_state(mdev, ns, CS_VERBOSE, NULL);
 out_unlock: