Btrfs: record first logical byte in memory

This'd save us a rbtree search which may become expensive in large filesystem.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 22f012d41fd0..9ee099f3f834 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1250,6 +1250,7 @@ struct btrfs_fs_info {
 
         /* block group cache stuff */
         spinlock_t block_group_cache_lock;
+        u64 first_logical_byte;
         struct rb_root block_group_cache_tree;
 
         /* keep track of unallocated space */