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Diffstat (limited to 'fs/btrfs/extent_map.c')
-rw-r--r--fs/btrfs/extent_map.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 5bc7a0d325e7..2c726b7b9faa 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -367,6 +367,54 @@ out:
}
/**
+ * search_extent_mapping - find a nearby 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.
+ *
+ * If one can't be found, any nearby extent may be returned
+ */
+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) {
+ em = NULL;
+ goto out;
+ }
+ if (IS_ERR(rb_node)) {
+ em = ERR_PTR(PTR_ERR(rb_node));
+ goto out;
+ }
+ em = rb_entry(rb_node, struct extent_map, rb_node);
+ goto found;
+
+ em = NULL;
+ goto out;
+
+found:
+ atomic_inc(&em->refs);
+out:
+ return em;
+}
+
+/**
* remove_extent_mapping - removes an extent_map from the extent tree
* @tree: extent tree to remove from
* @em: extent map beeing removed