Btrfs: clean up code for merging extent maps
Li Zefan [Thu, 14 Jul 2011 03:18:33 +0000 (03:18 +0000)]
unpin_extent_cache() and add_extent_mapping() shares the same code
that merges extent maps.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/extent_map.c

index df7a803..7c97b33 100644 (file)
@@ -183,22 +183,10 @@ static int mergable_maps(struct extent_map *prev, struct extent_map *next)
        return 0;
 }
 
-int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
+static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
 {
-       int ret = 0;
        struct extent_map *merge = NULL;
        struct rb_node *rb;
-       struct extent_map *em;
-
-       write_lock(&tree->lock);
-       em = lookup_extent_mapping(tree, start, len);
-
-       WARN_ON(!em || em->start != start);
-
-       if (!em)
-               goto out;
-
-       clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 
        if (em->start != 0) {
                rb = rb_prev(&em->rb_node);
@@ -225,6 +213,24 @@ int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
                merge->in_tree = 0;
                free_extent_map(merge);
        }
+}
+
+int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
+{
+       int ret = 0;
+       struct extent_map *em;
+
+       write_lock(&tree->lock);
+       em = lookup_extent_mapping(tree, start, len);
+
+       WARN_ON(!em || em->start != start);
+
+       if (!em)
+               goto out;
+
+       clear_bit(EXTENT_FLAG_PINNED, &em->flags);
+
+       try_merge_map(tree, em);
 
        free_extent_map(em);
 out:
@@ -247,7 +253,6 @@ int add_extent_mapping(struct extent_map_tree *tree,
                       struct extent_map *em)
 {
        int ret = 0;
-       struct extent_map *merge = NULL;
        struct rb_node *rb;
        struct extent_map *exist;
 
@@ -263,30 +268,8 @@ int add_extent_mapping(struct extent_map_tree *tree,
                goto out;
        }
        atomic_inc(&em->refs);
-       if (em->start != 0) {
-               rb = rb_prev(&em->rb_node);
-               if (rb)
-                       merge = rb_entry(rb, struct extent_map, rb_node);
-               if (rb && mergable_maps(merge, em)) {
-                       em->start = merge->start;
-                       em->len += merge->len;
-                       em->block_len += merge->block_len;
-                       em->block_start = merge->block_start;
-                       merge->in_tree = 0;
-                       rb_erase(&merge->rb_node, &tree->map);
-                       free_extent_map(merge);
-               }
-        }
-       rb = rb_next(&em->rb_node);
-       if (rb)
-               merge = rb_entry(rb, struct extent_map, rb_node);
-       if (rb && mergable_maps(em, merge)) {
-               em->len += merge->len;
-               em->block_len += merge->len;
-               rb_erase(&merge->rb_node, &tree->map);
-               merge->in_tree = 0;
-               free_extent_map(merge);
-       }
+
+       try_merge_map(tree, em);
 out:
        return ret;
 }