Btrfs: extent_map: use rb_first_cached
rb_first_cached() trades an extra pointer "leftmost" for doing the
same job as rb_first() but in O(1).
As evict_inode_truncate_pages() removes all extent mapping by always
looking for the first rb entry, it's helpful to use rb_first_cached
instead.
For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8ba7e5d..dd2140d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5222,10 +5222,10 @@ static void evict_inode_truncate_pages(struct inode *inode)
truncate_inode_pages_final(&inode->i_data);
write_lock(&map_tree->lock);
- while (!RB_EMPTY_ROOT(&map_tree->map)) {
+ while (!RB_EMPTY_ROOT(&map_tree->map.rb_root)) {
struct extent_map *em;
- node = rb_first(&map_tree->map);
+ node = rb_first_cached(&map_tree->map);
em = rb_entry(node, struct extent_map, rb_node);
clear_bit(EXTENT_FLAG_PINNED, &em->flags);
clear_bit(EXTENT_FLAG_LOGGING, &em->flags);