Re: [PATCH 7/7] xfs: force small EFIs for reaping btree extents

[Christoph Hellwig <hch@infradead.org>]

This generally looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

But as mentioned earlier I think it would be nice to share some
code between the normal xfs_defer_add and xfs_defer_add_barrier.

This would be the fold for this patch on top of the one previously
posted and a light merge fix for the pausing between:

diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index e70dc347074dc5..5d621e445e8ab9 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -753,6 +753,22 @@ xfs_defer_can_append(
 	return true;
 }
 
+/* Create a new pending item at the end of the intake list. */
+static struct xfs_defer_pending *
+xfs_defer_alloc(
+	struct xfs_trans		*tp,
+	enum xfs_defer_ops_type		type)
+{
+	struct xfs_defer_pending	*dfp;
+
+	dfp = kmem_cache_zalloc(xfs_defer_pending_cache,
+			GFP_NOFS | __GFP_NOFAIL);
+	dfp->dfp_type = type;
+	INIT_LIST_HEAD(&dfp->dfp_work);
+	list_add_tail(&dfp->dfp_list, &tp->t_dfops);
+	return dfp;
+};
+
 /* Add an item for later deferred processing. */
 struct xfs_defer_pending *
 xfs_defer_add(
@@ -760,29 +776,18 @@ xfs_defer_add(
 	enum xfs_defer_ops_type		type,
 	struct list_head		*li)
 {
-	struct xfs_defer_pending	*dfp = NULL;
 	const struct xfs_defer_op_type	*ops = defer_op_types[type];
+	struct xfs_defer_pending	*dfp;
 
 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
 	BUILD_BUG_ON(ARRAY_SIZE(defer_op_types) != XFS_DEFER_OPS_TYPE_MAX);
 
 	dfp = xfs_defer_find(tp, type);
-	if (!dfp || !xfs_defer_can_append(dfp, ops)) {
-		/* Create a new pending item at the end of the intake list. */
-		dfp = kmem_cache_zalloc(xfs_defer_pending_cache,
-				GFP_NOFS | __GFP_NOFAIL);
-		dfp->dfp_type = type;
-		dfp->dfp_intent = NULL;
-		dfp->dfp_done = NULL;
-		dfp->dfp_count = 0;
-		INIT_LIST_HEAD(&dfp->dfp_work);
-		list_add_tail(&dfp->dfp_list, &tp->t_dfops);
-	}
-
+	if (!dfp || !xfs_defer_can_append(dfp, ops))
+		dfp = xfs_defer_alloc(tp, type);
 	list_add_tail(li, &dfp->dfp_work);
 	trace_xfs_defer_add_item(tp->t_mountp, dfp, li);
 	dfp->dfp_count++;
-
 	return dfp;
 }
 
@@ -1106,19 +1111,10 @@ xfs_defer_add_barrier(
 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
 
 	/* If the last defer op added was a barrier, we're done. */
-	if (!list_empty(&tp->t_dfops)) {
-		dfp = list_last_entry(&tp->t_dfops,
-				struct xfs_defer_pending, dfp_list);
-		if (dfp->dfp_type == XFS_DEFER_OPS_TYPE_BARRIER)
-			return;
-	}
-
-	dfp = kmem_cache_zalloc(xfs_defer_pending_cache,
-			GFP_NOFS | __GFP_NOFAIL);
-	dfp->dfp_type = XFS_DEFER_OPS_TYPE_BARRIER;
-	INIT_LIST_HEAD(&dfp->dfp_work);
-	list_add_tail(&dfp->dfp_list, &tp->t_dfops);
-
+	dfp = xfs_defer_find(tp, XFS_DEFER_OPS_TYPE_BARRIER);
+	if (dfp)
+		return;
+	dfp = xfs_defer_alloc(tp, XFS_DEFER_OPS_TYPE_BARRIER);
 	trace_xfs_defer_add_item(tp->t_mountp, dfp, NULL);
 	dfp->dfp_count++;
 }