1 files changed, 57 insertions, 72 deletions

diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index 0425ca1..49d9cde 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -364,29 +364,31 @@ xfsaild_push(
 	xfs_log_item_t		*lip;
 	xfs_lsn_t		lsn;
 	xfs_lsn_t		target;
-	long			tout = 10;
+	long			tout;
 	int			stuck = 0;
+	int			flushing = 0;
 	int			count = 0;
-	int			push_xfsbufd = 0;
 
 	/*
-	 * If last time we ran we encountered pinned items, force the log first
-	 * and wait for it before pushing again.
+	 * If we encountered pinned items or did not finish writing out all
+	 * buffers the last time we ran, force the log first and wait for it
+	 * before pushing again.
 	 */
-	spin_lock(&ailp->xa_lock);
-	if (ailp->xa_last_pushed_lsn == 0 && ailp->xa_log_flush &&
-	    !list_empty(&ailp->xa_ail)) {
+	if (ailp->xa_log_flush && ailp->xa_last_pushed_lsn == 0 &&
+	    (!list_empty_careful(&ailp->xa_buf_list) ||
+	     xfs_ail_min_lsn(ailp))) {
 		ailp->xa_log_flush = 0;
-		spin_unlock(&ailp->xa_lock);
+
 		XFS_STATS_INC(xs_push_ail_flush);
 		xfs_log_force(mp, XFS_LOG_SYNC);
-		spin_lock(&ailp->xa_lock);
 	}
 
+	spin_lock(&ailp->xa_lock);
 	lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->xa_last_pushed_lsn);
 	if (!lip) {
 		/*
-		 * AIL is empty or our push has reached the end.
+		 * If the AIL is empty or our push has reached the end we are
+		 * done now.
 		 */
 		xfs_trans_ail_cursor_done(ailp, &cur);
 		spin_unlock(&ailp->xa_lock);
@@ -395,55 +397,42 @@ xfsaild_push(
 
 	XFS_STATS_INC(xs_push_ail);
 
-	/*
-	 * While the item we are looking at is below the given threshold
-	 * try to flush it out. We'd like not to stop until we've at least
-	 * tried to push on everything in the AIL with an LSN less than
-	 * the given threshold.
-	 *
-	 * However, we will stop after a certain number of pushes and wait
-	 * for a reduced timeout to fire before pushing further. This
-	 * prevents use from spinning when we can't do anything or there is
-	 * lots of contention on the AIL lists.
-	 */
 	lsn = lip->li_lsn;
 	target = ailp->xa_target;
 	while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) {
 		int	lock_result;
+
 		/*
-		 * If we can lock the item without sleeping, unlock the AIL
-		 * lock and flush the item.  Then re-grab the AIL lock so we
-		 * can look for the next item on the AIL. List changes are
-		 * handled by the AIL lookup functions internally
-		 *
-		 * If we can't lock the item, either its holder will flush it
-		 * or it is already being flushed or it is being relogged.  In
-		 * any of these case it is being taken care of and we can just
-		 * skip to the next item in the list.
+		 * Note that IOP_PUSH may unlock and reacquire the AIL lock.  We
+		 * rely on the AIL cursor implementation to be able to deal with
+		 * the dropped lock.
 		 */
-		lock_result = IOP_TRYLOCK(lip);
-		spin_unlock(&ailp->xa_lock);
+		lock_result = IOP_PUSH(lip, &ailp->xa_buf_list);
 		switch (lock_result) {
 		case XFS_ITEM_SUCCESS:
 			XFS_STATS_INC(xs_push_ail_success);
 			trace_xfs_ail_push(lip);
 
-			IOP_PUSH(lip);
 			ailp->xa_last_pushed_lsn = lsn;
 			break;
 
-		case XFS_ITEM_PUSHBUF:
-			XFS_STATS_INC(xs_push_ail_pushbuf);
-			trace_xfs_ail_pushbuf(lip);
-
-			if (!IOP_PUSHBUF(lip)) {
-				trace_xfs_ail_pushbuf_pinned(lip);
-				stuck++;
-				ailp->xa_log_flush++;
-			} else {
-				ailp->xa_last_pushed_lsn = lsn;
-			}
-			push_xfsbufd = 1;
+		case XFS_ITEM_FLUSHING:
+			/*
+			 * The item or its backing buffer is already beeing
+			 * flushed.  The typical reason for that is that an
+			 * inode buffer is locked because we already pushed the
+			 * updates to it as part of inode clustering.
+			 *
+			 * We do not want to to stop flushing just because lots
+			 * of items are already beeing flushed, but we need to
+			 * re-try the flushing relatively soon if most of the
+			 * AIL is beeing flushed.
+			 */
+			XFS_STATS_INC(xs_push_ail_flushing);
+			trace_xfs_ail_flushing(lip);
+
+			flushing++;
+			ailp->xa_last_pushed_lsn = lsn;
 			break;
 
 		case XFS_ITEM_PINNED:
@@ -453,23 +442,22 @@ xfsaild_push(
 			stuck++;
 			ailp->xa_log_flush++;
 			break;
-
 		case XFS_ITEM_LOCKED:
 			XFS_STATS_INC(xs_push_ail_locked);
 			trace_xfs_ail_locked(lip);
+
 			stuck++;
 			break;
-
 		default:
 			ASSERT(0);
 			break;
 		}
 
-		spin_lock(&ailp->xa_lock);
 		count++;
 
 		/*
 		 * Are there too many items we can't do anything with?
+		 *
 		 * If we we are skipping too many items because we can't flush
 		 * them or they are already being flushed, we back off and
 		 * given them time to complete whatever operation is being
@@ -491,42 +479,36 @@ xfsaild_push(
 	xfs_trans_ail_cursor_done(ailp, &cur);
 	spin_unlock(&ailp->xa_lock);
 
-	if (push_xfsbufd) {
-		/* we've got delayed write buffers to flush */
-		wake_up_process(mp->m_ddev_targp->bt_task);
-	}
+	if (xfs_buf_delwri_submit_nowait(&ailp->xa_buf_list))
+		ailp->xa_log_flush++;
 
-	/* assume we have more work to do in a short while */
+	if (!count || XFS_LSN_CMP(lsn, target) >= 0) {
 out_done:
-	if (!count) {
-		/* We're past our target or empty, so idle */
-		ailp->xa_last_pushed_lsn = 0;
-		ailp->xa_log_flush = 0;
-
-		tout = 50;
-	} else if (XFS_LSN_CMP(lsn, target) >= 0) {
 		/*
-		 * We reached the target so wait a bit longer for I/O to
-		 * complete and remove pushed items from the AIL before we
-		 * start the next scan from the start of the AIL.
+		 * We reached the target or the AIL is empty, so wait a bit
+		 * longer for I/O to complete and remove pushed items from the
+		 * AIL before we start the next scan from the start of the AIL.
 		 */
 		tout = 50;
 		ailp->xa_last_pushed_lsn = 0;
-	} else if ((stuck * 100) / count > 90) {
+	} else if (((stuck + flushing) * 100) / count > 90) {
 		/*
-		 * Either there is a lot of contention on the AIL or we
-		 * are stuck due to operations in progress. "Stuck" in this
-		 * case is defined as >90% of the items we tried to push
-		 * were stuck.
+		 * Either there is a lot of contention on the AIL or we are
+		 * stuck due to operations in progress. "Stuck" in this case
+		 * is defined as >90% of the items we tried to push were stuck.
 		 *
 		 * Backoff a bit more to allow some I/O to complete before
-		 * restarting from the start of the AIL. This prevents us
-		 * from spinning on the same items, and if they are pinned will
-		 * all the restart to issue a log force to unpin the stuck
-		 * items.
+		 * restarting from the start of the AIL. This prevents us from
+		 * spinning on the same items, and if they are pinned will all
+		 * the restart to issue a log force to unpin the stuck items.
 		 */
 		tout = 20;
 		ailp->xa_last_pushed_lsn = 0;
+	} else {
+		/*
+		 * Assume we have more work to do in a short while.
+		 */
+		tout = 10;
 	}
 
 	return tout;
@@ -539,6 +521,8 @@ xfsaild(
 	struct xfs_ail	*ailp = data;
 	long		tout = 0;	/* milliseconds */
 
+	current->flags |= PF_MEMALLOC;
+
 	while (!kthread_should_stop()) {
 		if (tout && tout <= 20)
 			__set_current_state(TASK_KILLABLE);
@@ -794,6 +778,7 @@ xfs_trans_ail_init(
 	INIT_LIST_HEAD(&ailp->xa_ail);
 	INIT_LIST_HEAD(&ailp->xa_cursors);
 	spin_lock_init(&ailp->xa_lock);
+	INIT_LIST_HEAD(&ailp->xa_buf_list);
 	init_waitqueue_head(&ailp->xa_empty);
 
 	ailp->xa_task = kthread_run(xfsaild, ailp, "xfsaild/%s",