Btrfs: Allocator improvements

Reduce CPU time searching for free blocks by optimizing find_first_extent_bit

Fix find_free_extent to make better use of the last_alloc hint.  Before it
was often finding blocks just before the hint.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 151fdada4dc4..fcc4bb078c24 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -81,6 +81,15 @@ struct extent_buffer {
 
 struct extent_map_tree;
 
+static inline struct extent_state *extent_state_next(struct extent_state *state)
+{
+        struct rb_node *node;
+        node = rb_next(&state->rb_node);
+        if (!node)
+                return NULL;
+        return rb_entry(node, struct extent_state, rb_node);
+}
+
 typedef struct extent_map *(get_extent_t)(struct inode *inode,
                                           struct page *page,
                                           size_t page_offset,
@@ -122,6 +131,8 @@ int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
                      gfp_t mask);
 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
                           u64 *start_ret, u64 *end_ret, int bits);
+struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree,
+                                                 u64 start, int bits);
 int extent_invalidatepage(struct extent_io_tree *tree,
                           struct page *page, unsigned long offset);
 int extent_write_full_page(struct extent_io_tree *tree, struct page *page,