1 files changed, 51 insertions, 4 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 30c9365861e6..5bc7a0d325e7 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -36,7 +36,7 @@ void extent_map_exit(void)
 void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
 {
         tree->map.rb_node = NULL;
-        spin_lock_init(&tree->lock);
+        rwlock_init(&tree->lock);
 }
 
 /**
@@ -198,6 +198,56 @@ 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)
+{
+        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->start != start || !em);
+
+        if (!em)
+                goto out;
+
+        clear_bit(EXTENT_FLAG_PINNED, &em->flags);
+
+        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);
+        }
+
+        free_extent_map(em);
+out:
+        write_unlock(&tree->lock);
+        return ret;
+
+}
+
 /**
  * add_extent_mapping - add new extent map to the extent tree
  * @tree:       tree to insert new map in
@@ -222,7 +272,6 @@ int add_extent_mapping(struct extent_map_tree *tree,
                 ret = -EEXIST;
                 goto out;
         }
-        assert_spin_locked(&tree->lock);
         rb = tree_insert(&tree->map, em->start, &em->rb_node);
         if (rb) {
                 ret = -EEXIST;
@@ -285,7 +334,6 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
         struct rb_node *next = NULL;
         u64 end = range_end(start, len);
 
-        assert_spin_locked(&tree->lock);
         rb_node = __tree_search(&tree->map, start, &prev, &next);
         if (!rb_node && prev) {
                 em = rb_entry(prev, struct extent_map, rb_node);
@@ -331,7 +379,6 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
         int ret = 0;
 
         WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
-        assert_spin_locked(&tree->lock);
         rb_erase(&em->rb_node, &tree->map);
         em->in_tree = 0;
         return ret;