ext4: add proc files to monitor new structures

This patch adds a new file "mb_structs_summary" which allows us to see
the summary of the new allocator structures added in this
series. Here's the sample output of file:

optimize_scan: 1
max_free_order_lists:
        list_order_0_groups: 0
        list_order_1_groups: 0
        list_order_2_groups: 0
        list_order_3_groups: 0
        list_order_4_groups: 0
        list_order_5_groups: 0
        list_order_6_groups: 0
        list_order_7_groups: 0
        list_order_8_groups: 0
        list_order_9_groups: 0
        list_order_10_groups: 0
        list_order_11_groups: 0
        list_order_12_groups: 0
        list_order_13_groups: 40
fragment_size_tree:
        tree_min: 16384
        tree_max: 32768
        tree_nodes: 40

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20210401172129.189766-7-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 42df628b35e5ac95d217fa34b2dd56662a1bf95d..369b2d2c8850e8ba1e97341e7fd328075b96c726 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2872,6 +2872,7 @@ int __init ext4_fc_init_dentry_cache(void);
 
 /* mballoc.c */
 extern const struct seq_operations ext4_mb_seq_groups_ops;
+extern const struct seq_operations ext4_mb_seq_structs_summary_ops;
 extern long ext4_mb_stats;
 extern long ext4_mb_max_to_scan;
 extern int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset);

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c62555598a8e0782c34ae374e2d0b8ca24c067af..bf180b9e90625f7d60d90240947b4c000eccd9a6 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2963,6 +2963,92 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
        return 0;
 }
 
+static void *ext4_mb_seq_structs_summary_start(struct seq_file *seq, loff_t *pos)
+{
+       struct super_block *sb = PDE_DATA(file_inode(seq->file));
+       unsigned long position;
+
+       read_lock(&EXT4_SB(sb)->s_mb_rb_lock);
+
+       if (*pos < 0 || *pos >= MB_NUM_ORDERS(sb) + 1)
+               return NULL;
+       position = *pos + 1;
+       return (void *) ((unsigned long) position);
+}
+
+static void *ext4_mb_seq_structs_summary_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       struct super_block *sb = PDE_DATA(file_inode(seq->file));
+       unsigned long position;
+
+       ++*pos;
+       if (*pos < 0 || *pos >= MB_NUM_ORDERS(sb) + 1)
+               return NULL;
+       position = *pos + 1;
+       return (void *) ((unsigned long) position);
+}
+
+static int ext4_mb_seq_structs_summary_show(struct seq_file *seq, void *v)
+{
+       struct super_block *sb = PDE_DATA(file_inode(seq->file));
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       unsigned long position = ((unsigned long) v);
+       struct ext4_group_info *grp;
+       struct rb_node *n;
+       unsigned int count, min, max;
+
+       position--;
+       if (position >= MB_NUM_ORDERS(sb)) {
+               seq_puts(seq, "fragment_size_tree:\n");
+               n = rb_first(&sbi->s_mb_avg_fragment_size_root);
+               if (!n) {
+                       seq_puts(seq, "\ttree_min: 0\n\ttree_max: 0\n\ttree_nodes: 0\n");
+                       return 0;
+               }
+               grp = rb_entry(n, struct ext4_group_info, bb_avg_fragment_size_rb);
+               min = grp->bb_fragments ? grp->bb_free / grp->bb_fragments : 0;
+               count = 1;
+               while (rb_next(n)) {
+                       count++;
+                       n = rb_next(n);
+               }
+               grp = rb_entry(n, struct ext4_group_info, bb_avg_fragment_size_rb);
+               max = grp->bb_fragments ? grp->bb_free / grp->bb_fragments : 0;
+
+               seq_printf(seq, "\ttree_min: %u\n\ttree_max: %u\n\ttree_nodes: %u\n",
+                          min, max, count);
+               return 0;
+       }
+
+       if (position == 0) {
+               seq_printf(seq, "optimize_scan: %d\n",
+                          test_opt2(sb, MB_OPTIMIZE_SCAN) ? 1 : 0);
+               seq_puts(seq, "max_free_order_lists:\n");
+       }
+       count = 0;
+       list_for_each_entry(grp, &sbi->s_mb_largest_free_orders[position],
+                           bb_largest_free_order_node)
+               count++;
+       seq_printf(seq, "\tlist_order_%u_groups: %u\n",
+                  (unsigned int)position, count);
+
+       return 0;
+}
+
+static void ext4_mb_seq_structs_summary_stop(struct seq_file *seq, void *v)
+{
+       struct super_block *sb = PDE_DATA(file_inode(seq->file));
+
+       read_unlock(&EXT4_SB(sb)->s_mb_rb_lock);
+}
+
+const struct seq_operations ext4_mb_seq_structs_summary_ops = {
+       .start  = ext4_mb_seq_structs_summary_start,
+       .next   = ext4_mb_seq_structs_summary_next,
+       .stop   = ext4_mb_seq_structs_summary_stop,
+       .show   = ext4_mb_seq_structs_summary_show,
+};
+
 static struct kmem_cache *get_groupinfo_cache(int blocksize_bits)
 {
        int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;

diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 8716790e7e21fbb0c4f6c694ea81df6ba1ee2c06..6f825dedc3d4257b389024167a434e9fe901be89 100644 (file)
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -534,6 +534,8 @@ int ext4_register_sysfs(struct super_block *sb)
                                &ext4_mb_seq_groups_ops, sb);
                proc_create_single_data("mb_stats", 0444, sbi->s_proc,
                                ext4_seq_mb_stats_show, sb);
+               proc_create_seq_data("mb_structs_summary", 0444, sbi->s_proc,
+                               &ext4_mb_seq_structs_summary_ops, sb);
        }
        return 0;
 }