Btrfs: clean up code for extent_map lookup

lookup_extent_map() and search_extent_map() can share most of code.

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

1 files changed, 29 insertions, 56 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 911a9db801e0..df7a803005fb 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -299,19 +299,8 @@ static u64 range_end(u64 start, u64 len)
         return start + len;
 }
 
-/**
- * lookup_extent_mapping - lookup extent_map
- * @tree:       tree to lookup in
- * @start:      byte offset to start the search
- * @len:        length of the lookup range
- *
- * Find and return the first extent_map struct in @tree that intersects the
- * [start, len] range.  There may be additional objects in the tree that
- * intersect, so check the object returned carefully to make sure that no
- * additional lookups are needed.
- */
-struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
-                                         u64 start, u64 len)
+struct extent_map *__lookup_extent_mapping(struct extent_map_tree *tree,
+                                           u64 start, u64 len, int strict)
 {
         struct extent_map *em;
         struct rb_node *rb_node;
@@ -320,38 +309,42 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
         u64 end = range_end(start, len);
 
         rb_node = __tree_search(&tree->map, start, &prev, &next);
-        if (!rb_node && prev) {
-                em = rb_entry(prev, struct extent_map, rb_node);
-                if (end > em->start && start < extent_map_end(em))
-                        goto found;
-        }
-        if (!rb_node && next) {
-                em = rb_entry(next, struct extent_map, rb_node);
-                if (end > em->start && start < extent_map_end(em))
-                        goto found;
-        }
         if (!rb_node) {
-                em = NULL;
-                goto out;
-        }
-        if (IS_ERR(rb_node)) {
-                em = ERR_CAST(rb_node);
-                goto out;
+                if (prev)
+                        rb_node = prev;
+                else if (next)
+                        rb_node = next;
+                else
+                        return NULL;
         }
+
         em = rb_entry(rb_node, struct extent_map, rb_node);
-        if (end > em->start && start < extent_map_end(em))
-                goto found;
 
-        em = NULL;
-        goto out;
+        if (strict && !(end > em->start && start < extent_map_end(em)))
+                return NULL;
 
-found:
         atomic_inc(&em->refs);
-out:
         return em;
 }
 
 /**
+ * lookup_extent_mapping - lookup extent_map
+ * @tree:       tree to lookup in
+ * @start:      byte offset to start the search
+ * @len:        length of the lookup range
+ *
+ * Find and return the first extent_map struct in @tree that intersects the
+ * [start, len] range.  There may be additional objects in the tree that
+ * intersect, so check the object returned carefully to make sure that no
+ * additional lookups are needed.
+ */
+struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
+                                         u64 start, u64 len)
+{
+        return __lookup_extent_mapping(tree, start, len, 1);
+}
+
+/**
  * search_extent_mapping - find a nearby extent map
  * @tree:       tree to lookup in
  * @start:      byte offset to start the search
@@ -365,27 +358,7 @@ out:
 struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
                                          u64 start, u64 len)
 {
-        struct extent_map *em;
-        struct rb_node *rb_node;
-        struct rb_node *prev = NULL;
-        struct rb_node *next = NULL;
-
-        rb_node = __tree_search(&tree->map, start, &prev, &next);
-        if (!rb_node && prev) {
-                em = rb_entry(prev, struct extent_map, rb_node);
-                goto found;
-        }
-        if (!rb_node && next) {
-                em = rb_entry(next, struct extent_map, rb_node);
-                goto found;
-        }
-        if (!rb_node)
-                return NULL;
-
-        em = rb_entry(rb_node, struct extent_map, rb_node);
-found:
-        atomic_inc(&em->refs);
-        return em;
+        return __lookup_extent_mapping(tree, start, len, 0);
 }
 
 /**