---

yaml
---
r: 294605
b: refs/heads/master
c: 09a423a
h: refs/heads/master
i:
  294603: 127d427
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 70b5437653d9c6c8de287affd38836cce98ebde5
+refs/heads/master: 09a423a3d6c70905f1090f01aadb8e6abff527ce

trunk/fs/xfs/xfs_log.c

@@ -760,37 +760,35 @@ xfs_log_item_init(
 	INIT_LIST_HEAD(&item->li_cil);
 }
 
+/*
+ * Wake up processes waiting for log space after we have moved the log tail.
+ *
+ * If opportunistic is set wake up one waiter even if we do not have enough
+ * free space by our strict accounting.
+ */
 void
-xfs_log_move_tail(xfs_mount_t	*mp,
-		  xfs_lsn_t	tail_lsn)
+xfs_log_space_wake(
+	struct xfs_mount	*mp,
+	bool			opportunistic)
 {
-	xlog_ticket_t	*tic;
-	xlog_t		*log = mp->m_log;
-	int		need_bytes, free_bytes;
+	struct xlog_ticket	*tic;
+	struct log		*log = mp->m_log;
+	int			need_bytes, free_bytes;
 
 	if (XLOG_FORCED_SHUTDOWN(log))
 		return;
 
-	if (tail_lsn == 0)
-		tail_lsn = atomic64_read(&log->l_last_sync_lsn);
-
-	/* tail_lsn == 1 implies that we weren't passed a valid value.  */
-	if (tail_lsn != 1)
-		atomic64_set(&log->l_tail_lsn, tail_lsn);
-
 	if (!list_empty_careful(&log->l_writeq)) {
-#ifdef DEBUG
-		if (log->l_flags & XLOG_ACTIVE_RECOVERY)
-			panic("Recovery problem");
-#endif
+		ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+
 		spin_lock(&log->l_grant_write_lock);
 		free_bytes = xlog_space_left(log, &log->l_grant_write_head);
 		list_for_each_entry(tic, &log->l_writeq, t_queue) {
 			ASSERT(tic->t_flags & XLOG_TIC_PERM_RESERV);
 
-			if (free_bytes < tic->t_unit_res && tail_lsn != 1)
+			if (free_bytes < tic->t_unit_res && !opportunistic)
 				break;
-			tail_lsn = 0;
+			opportunistic = false;
 			free_bytes -= tic->t_unit_res;
 			trace_xfs_log_regrant_write_wake_up(log, tic);
 			wake_up(&tic->t_wait);
@@ -799,20 +797,18 @@ xfs_log_move_tail(xfs_mount_t	*mp,
 	}
 
 	if (!list_empty_careful(&log->l_reserveq)) {
-#ifdef DEBUG
-		if (log->l_flags & XLOG_ACTIVE_RECOVERY)
-			panic("Recovery problem");
-#endif
+		ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+
 		spin_lock(&log->l_grant_reserve_lock);
 		free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
 		list_for_each_entry(tic, &log->l_reserveq, t_queue) {
 			if (tic->t_flags & XLOG_TIC_PERM_RESERV)
 				need_bytes = tic->t_unit_res*tic->t_cnt;
 			else
 				need_bytes = tic->t_unit_res;
-			if (free_bytes < need_bytes && tail_lsn != 1)
+			if (free_bytes < need_bytes && !opportunistic)
 				break;
-			tail_lsn = 0;
+			opportunistic = false;
 			free_bytes -= need_bytes;
 			trace_xfs_log_grant_wake_up(log, tic);
 			wake_up(&tic->t_wait);
@@ -867,21 +863,7 @@ xfs_log_need_covered(xfs_mount_t *mp)
 	return needed;
 }
 
-/******************************************************************************
- *
- *	local routines
- *
- ******************************************************************************
- */
-
-/* xfs_trans_tail_ail returns 0 when there is nothing in the list.
- * The log manager must keep track of the last LR which was committed
- * to disk.  The lsn of this LR will become the new tail_lsn whenever
- * xfs_trans_tail_ail returns 0.  If we don't do this, we run into
- * the situation where stuff could be written into the log but nothing
- * was ever in the AIL when asked.  Eventually, we panic since the
- * tail hits the head.
- *
+/*
  * We may be holding the log iclog lock upon entering this routine.
  */
 xfs_lsn_t
@@ -891,10 +873,17 @@ xlog_assign_tail_lsn(
 	xfs_lsn_t		tail_lsn;
 	struct log		*log = mp->m_log;
 
+	/*
+	 * To make sure we always have a valid LSN for the log tail we keep
+	 * track of the last LSN which was committed in log->l_last_sync_lsn,
+	 * and use that when the AIL was empty and xfs_ail_min_lsn returns 0.
+	 *
+	 * If the AIL has been emptied we also need to wake any process
+	 * waiting for this condition.
+	 */
 	tail_lsn = xfs_ail_min_lsn(mp->m_ail);
 	if (!tail_lsn)
 		tail_lsn = atomic64_read(&log->l_last_sync_lsn);
-
 	atomic64_set(&log->l_tail_lsn, tail_lsn);
 	return tail_lsn;
 }
@@ -2759,9 +2748,8 @@ xlog_ungrant_log_space(xlog_t	     *log,
 
 	trace_xfs_log_ungrant_exit(log, ticket);
 
-	xfs_log_move_tail(log->l_mp, 1);
-}	/* xlog_ungrant_log_space */
-
+	xfs_log_space_wake(log->l_mp, true);
+}
 
 /*
  * Flush iclog to disk if this is the last reference to the given iclog and

trunk/fs/xfs/xfs_log.h

@@ -160,8 +160,9 @@ int	  xfs_log_mount(struct xfs_mount	*mp,
 			xfs_daddr_t		start_block,
 			int		 	num_bblocks);
 int	  xfs_log_mount_finish(struct xfs_mount *mp);
-void	  xfs_log_move_tail(struct xfs_mount	*mp,
-			    xfs_lsn_t		tail_lsn);
+xfs_lsn_t xlog_assign_tail_lsn(struct xfs_mount *mp);
+void	  xfs_log_space_wake(struct xfs_mount	*mp,
+			     bool		opportunistic);
 int	  xfs_log_notify(struct xfs_mount	*mp,
 			 struct xlog_in_core	*iclog,
 			 xfs_log_callback_t	*callback_entry);

trunk/fs/xfs/xfs_log_priv.h

@@ -545,7 +545,6 @@ typedef struct log {
 #define XLOG_FORCED_SHUTDOWN(log)	((log)->l_flags & XLOG_IO_ERROR)
 
 /* common routines */
-extern xfs_lsn_t xlog_assign_tail_lsn(struct xfs_mount *mp);
 extern int	 xlog_recover(xlog_t *log);
 extern int	 xlog_recover_finish(xlog_t *log);
 extern void	 xlog_pack_data(xlog_t *log, xlog_in_core_t *iclog, int);

trunk/fs/xfs/xfs_trans_ail.c

@@ -643,15 +643,15 @@ xfs_trans_unlocked_item(
 	 * at the tail, it doesn't matter what result we get back.  This
 	 * is slightly racy because since we were just unlocked, we could
 	 * go to sleep between the call to xfs_ail_min and the call to
-	 * xfs_log_move_tail, have someone else lock us, commit to us disk,
+	 * xfs_log_space_wake, have someone else lock us, commit to us disk,
 	 * move us out of the tail of the AIL, and then we wake up.  However,
-	 * the call to xfs_log_move_tail() doesn't do anything if there's
+	 * the call to xfs_log_space_wake() doesn't do anything if there's
 	 * not enough free space to wake people up so we're safe calling it.
 	 */
 	min_lip = xfs_ail_min(ailp);
 
 	if (min_lip == lip)
-		xfs_log_move_tail(ailp->xa_mount, 1);
+		xfs_log_space_wake(ailp->xa_mount, true);
 }	/* xfs_trans_unlocked_item */
 
 /*
@@ -685,7 +685,6 @@ xfs_trans_ail_update_bulk(
 	xfs_lsn_t		lsn) __releases(ailp->xa_lock)
 {
 	xfs_log_item_t		*mlip;
-	xfs_lsn_t		tail_lsn;
 	int			mlip_changed = 0;
 	int			i;
 	LIST_HEAD(tmp);
@@ -712,22 +711,12 @@ xfs_trans_ail_update_bulk(
 
 	if (!list_empty(&tmp))
 		xfs_ail_splice(ailp, cur, &tmp, lsn);
+	spin_unlock(&ailp->xa_lock);
 
-	if (!mlip_changed) {
-		spin_unlock(&ailp->xa_lock);
-		return;
+	if (mlip_changed && !XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
+		xlog_assign_tail_lsn(ailp->xa_mount);
+		xfs_log_space_wake(ailp->xa_mount, false);
 	}
-
-	/*
-	 * It is not safe to access mlip after the AIL lock is dropped, so we
-	 * must get a copy of li_lsn before we do so.  This is especially
-	 * important on 32-bit platforms where accessing and updating 64-bit
-	 * values like li_lsn is not atomic.
-	 */
-	mlip = xfs_ail_min(ailp);
-	tail_lsn = mlip->li_lsn;
-	spin_unlock(&ailp->xa_lock);
-	xfs_log_move_tail(ailp->xa_mount, tail_lsn);
 }
 
 /*
@@ -758,7 +747,6 @@ xfs_trans_ail_delete_bulk(
 	int			nr_items) __releases(ailp->xa_lock)
 {
 	xfs_log_item_t		*mlip;
-	xfs_lsn_t		tail_lsn;
 	int			mlip_changed = 0;
 	int			i;
 
@@ -785,23 +773,12 @@ xfs_trans_ail_delete_bulk(
 		if (mlip == lip)
 			mlip_changed = 1;
 	}
+	spin_unlock(&ailp->xa_lock);
 
-	if (!mlip_changed) {
-		spin_unlock(&ailp->xa_lock);
-		return;
+	if (mlip_changed && !XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
+		xlog_assign_tail_lsn(ailp->xa_mount);
+		xfs_log_space_wake(ailp->xa_mount, false);
 	}
-
-	/*
-	 * It is not safe to access mlip after the AIL lock is dropped, so we
-	 * must get a copy of li_lsn before we do so.  This is especially
-	 * important on 32-bit platforms where accessing and updating 64-bit
-	 * values like li_lsn is not atomic. It is possible we've emptied the
-	 * AIL here, so if that is the case, pass an LSN of 0 to the tail move.
-	 */
-	mlip = xfs_ail_min(ailp);
-	tail_lsn = mlip ? mlip->li_lsn : 0;
-	spin_unlock(&ailp->xa_lock);
-	xfs_log_move_tail(ailp->xa_mount, tail_lsn);
 }
 
 /*