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, 4 insertions, 4 deletions

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index c06886abd658..546c7dd869e1 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -938,10 +938,10 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
                 ext4_group_t flex_group;
                 flex_group = ext4_flex_group(sbi, input->group);
-                sbi->s_flex_groups[flex_group].free_blocks +=
-                        input->free_blocks_count;
-                sbi->s_flex_groups[flex_group].free_inodes +=
-                        EXT4_INODES_PER_GROUP(sb);
+                atomic_add(input->free_blocks_count,
+                           &sbi->s_flex_groups[flex_group].free_blocks);
+                atomic_add(EXT4_INODES_PER_GROUP(sb),
+                           &sbi->s_flex_groups[flex_group].free_inodes);
         }
 
         ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);