3 files changed, 20 insertions, 5 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 8d1364d385d6..b8cbc8d5c7f7 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -407,7 +407,8 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
 
 	WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
 	rb_erase(&em->rb_node, &tree->map);
-	list_del_init(&em->list);
+	if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
+		list_del_init(&em->list);
 	em->in_tree = 0;
 	return ret;
 }
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 8e6294b51357..679225555f7b 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -13,6 +13,7 @@
 #define EXTENT_FLAG_COMPRESSED 1
 #define EXTENT_FLAG_VACANCY 2 /* no file extent item found */
 #define EXTENT_FLAG_PREALLOC 3 /* pre-allocated extent */
+#define EXTENT_FLAG_LOGGING 4 /* Logging this extent */
 
 struct extent_map {
 	struct rb_node rb_node;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 038a5229404a..ed1f7ce7219a 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2945,6 +2945,9 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 		list_del_init(&em->list);
 		if (em->generation <= test_gen)
 			continue;
+		/* Need a ref to keep it from getting evicted from cache */
+		atomic_inc(&em->refs);
+		set_bit(EXTENT_FLAG_LOGGING, &em->flags);
 		list_add_tail(&em->list, &extents);
 	}
 
@@ -2954,13 +2957,18 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 		em = list_entry(extents.next, struct extent_map, list);
 
 		list_del_init(&em->list);
+		clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
 
 		/*
 		 * If we had an error we just need to delete everybody from our
 		 * private list.
 		 */
-		if (ret)
+		if (ret) {
+			free_extent_map(em);
 			continue;
+		}
+
+		write_unlock(&tree->lock);
 
 		/*
 		 * If the previous EM and the last extent we left off on aren't
@@ -2971,21 +2979,26 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 			ret = copy_items(trans, inode, dst_path, args.src,
 					 args.start_slot, args.nr,
 					 LOG_INODE_ALL);
-			if (ret)
+			if (ret) {
+				free_extent_map(em);
+				write_lock(&tree->lock);
 				continue;
+			}
 			btrfs_release_path(path);
 			args.nr = 0;
 		}
 
 		ret = log_one_extent(trans, inode, root, em, path, dst_path, &args);
+		free_extent_map(em);
+		write_lock(&tree->lock);
 	}
+	WARN_ON(!list_empty(&extents));
+	write_unlock(&tree->lock);
 
 	if (!ret && args.nr)
 		ret = copy_items(trans, inode, dst_path, args.src,
 				 args.start_slot, args.nr, LOG_INODE_ALL);
 	btrfs_release_path(path);
-	WARN_ON(!list_empty(&extents));
-	write_unlock(&tree->lock);
 	return ret;
 }