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>

3 files changed, 31 insertions, 17 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index e52b48f86ed4..46aaaa2ed4c5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -172,6 +172,7 @@ struct ext4_group_desc
 struct flex_groups {
         atomic_t free_inodes;
         atomic_t free_blocks;
+        atomic_t used_dirs;
 };
 
 #define EXT4_BG_INODE_UNINIT    0x0001 /* Inode table/bitmap not in use */
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 5f393927fd25..47b84e8df568 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -267,6 +267,13 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
                         if (is_directory) {
                                 count = ext4_used_dirs_count(sb, gdp) - 1;
                                 ext4_used_dirs_set(sb, gdp, count);
+                                if (sbi->s_log_groups_per_flex) {
+                                        ext4_group_t f;
+
+                                        f = ext4_flex_group(sbi, block_group);
+                                        atomic_dec(&sbi->s_flex_groups[f].free_inodes);
+                                }
+
                         }
                         gdp->bg_checksum = ext4_group_desc_csum(sbi,
                                                         block_group, gdp);
@@ -424,25 +431,24 @@ void get_orlov_stats(struct super_block *sb, ext4_group_t g,
                        int flex_size, struct orlov_stats *stats)
 {
         struct ext4_group_desc *desc;
-        ext4_group_t            ngroups = EXT4_SB(sb)->s_groups_count;
-        int                     i;
-
-        stats->free_inodes = 0;
-        stats->free_blocks = 0;
-        stats->used_dirs = 0;
+        struct flex_groups *flex_group = EXT4_SB(sb)->s_flex_groups;
 
-        g *= flex_size;
-
-        for (i = 0; i < flex_size; i++) {
-                if (g >= ngroups)
-                        break;
-                desc = ext4_get_group_desc(sb, g++, NULL);
-                if (!desc)
-                        continue;
+        if (flex_size > 1) {
+                stats->free_inodes = atomic_read(&flex_group[g].free_inodes);
+                stats->free_blocks = atomic_read(&flex_group[g].free_blocks);
+                stats->used_dirs = atomic_read(&flex_group[g].used_dirs);
+                return;
+        }
 
-                stats->free_inodes += ext4_free_inodes_count(sb, desc);
-                stats->free_blocks += ext4_free_blks_count(sb, desc);
-                stats->used_dirs += ext4_used_dirs_count(sb, desc);
+        desc = ext4_get_group_desc(sb, g, NULL);
+        if (desc) {
+                stats->free_inodes = ext4_free_inodes_count(sb, desc);
+                stats->free_blocks = ext4_free_blks_count(sb, desc);
+                stats->used_dirs = ext4_used_dirs_count(sb, desc);
+        } else {
+                stats->free_inodes = 0;
+                stats->free_blocks = 0;
+                stats->used_dirs = 0;
         }
 }
 
@@ -765,6 +771,11 @@ static int ext4_claim_inode(struct super_block *sb,
         if (S_ISDIR(mode)) {
                 count = ext4_used_dirs_count(sb, gdp) + 1;
                 ext4_used_dirs_set(sb, gdp, count);
+                if (sbi->s_log_groups_per_flex) {
+                        ext4_group_t f = ext4_flex_group(sbi, group);
+
+                        atomic_inc(&sbi->s_flex_groups[f].free_inodes);
+                }
         }
         gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
 err_ret:
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;