Btrfs: clean up code for merging extent maps

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>

1 files changed, 21 insertions, 38 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index df7a803005fb..7c97b3301459 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -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;
 }