ext4: Use struct flex_groups to calculate get_orlov_stats()

Instead of looping over all of the block groups in a flex group
summing their summary statistics, start tracking used_dirs in struct
flex_groups, and use struct flex_groups instead.  This should save a
bit of CPU for mkdir-heavy workloads.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6b5d5c6399fa..b9aefceb41e7 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1634,6 +1634,8 @@ static int ext4_fill_flex_info(struct super_block *sb)
                            ext4_free_inodes_count(sb, gdp));
                 atomic_set(&sbi->s_flex_groups[flex_group].free_blocks,
                            ext4_free_blks_count(sb, gdp));
+                atomic_set(&sbi->s_flex_groups[flex_group].used_dirs,
+                           ext4_used_dirs_count(sb, gdp));
         }
 
         return 1;