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>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c4c4309..e72c72a 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3044,9 +3044,8 @@
if (sbi->s_log_groups_per_flex) {
ext4_group_t flex_group = ext4_flex_group(sbi,
ac->ac_b_ex.fe_group);
- spin_lock(sb_bgl_lock(sbi, flex_group));
- sbi->s_flex_groups[flex_group].free_blocks -= ac->ac_b_ex.fe_len;
- spin_unlock(sb_bgl_lock(sbi, flex_group));
+ atomic_sub(ac->ac_b_ex.fe_len,
+ &sbi->s_flex_groups[flex_group].free_blocks);
}
err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
@@ -4884,9 +4883,7 @@
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 += count;
- spin_unlock(sb_bgl_lock(sbi, flex_group));
+ atomic_add(count, &sbi->s_flex_groups[flex_group].free_blocks);
}
ext4_mb_release_desc(&e4b);