ext4: Use atomic_t's in struct flex_groups

Reduce pressure on the sb_bgl_lock family of locks by using atomic_t's
to track the number of free blocks and inodes in each flex_group.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 2 insertions, 3 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index b37b12875582..53c72ad85877 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -470,9 +470,8 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 
         if (sbi->s_log_groups_per_flex) {
                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
-                spin_lock(sb_bgl_lock(sbi, flex_group));
-                sbi->s_flex_groups[flex_group].free_blocks += blocks_freed;
-                spin_unlock(sb_bgl_lock(sbi, flex_group));
+                atomic_add(blocks_freed,
+                           &sbi->s_flex_groups[flex_group].free_blocks);
         }
         /*
          * request to reload the buddy with the