With CONFIG_FS_IOSTATS, filesystem can attach an array of counters to
struct super_block by calling sb_iostats_init().
These counters will be used to collect per-sb I/O statistics and display
them in /proc/<pid>/mountstats.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/Kconfig | 8 +++
fs/super.c | 2 +
include/linux/fs.h | 10 ++-
include/linux/fs_iostats.h | 127 +++++++++++++++++++++++++++++++++++++
4 files changed, 145 insertions(+), 2 deletions(-)
create mode 100644 include/linux/fs_iostats.h
diff --git a/fs/Kconfig b/fs/Kconfig
index 6c7dc1387beb..394d9da6bda9 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -15,6 +15,14 @@ config VALIDATE_FS_PARSER
Enable this to perform validation of the parameter description for a
filesystem when it is registered.
+config FS_IOSTATS
+ bool "Enable generic filesystem I/O statistics"
+ help
+ Enable this to allow collecting filesystem I/O statistics and display
+ them in /proc/<pid>/mountstats.
+
+ Say N if unsure.
+
config FS_IOMAP
bool
diff --git a/fs/super.c b/fs/super.c
index f1d4a193602d..c447cadb402b 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -36,6 +36,7 @@
#include <linux/lockdep.h>
#include <linux/user_namespace.h>
#include <linux/fs_context.h>
+#include <linux/fs_iostats.h>
#include <uapi/linux/mount.h>
#include "internal.h"
@@ -290,6 +291,7 @@ static void __put_super(struct super_block *s)
WARN_ON(s->s_dentry_lru.node);
WARN_ON(s->s_inode_lru.node);
WARN_ON(!list_empty(&s->s_mounts));
+ sb_iostats_destroy(s);
security_sb_free(s);
fscrypt_sb_free(s);
put_user_ns(s->s_user_ns);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e2d892b201b0..a71c94cbb6c1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1454,6 +1454,8 @@ struct sb_writers {
struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
};
+struct sb_iostats;
+
struct super_block {
struct list_head s_list; /* Keep this first */
dev_t s_dev; /* search index; _not_ kdev_t */
@@ -1508,8 +1510,12 @@ struct super_block {
/* Granularity of c/m/atime in ns (cannot be worse than a second) */
u32 s_time_gran;
/* Time limits for c/m/atime in seconds */
- time64_t s_time_min;
- time64_t s_time_max;
+ time64_t s_time_min;
+ time64_t s_time_max;
+#ifdef CONFIG_FS_IOSTATS
+ /* Optional per-sb I/O stats */
+ struct sb_iostats *s_iostats;
+#endif
#ifdef CONFIG_FSNOTIFY
__u32 s_fsnotify_mask;
struct fsnotify_mark_connector __rcu *s_fsnotify_marks;
diff --git a/include/linux/fs_iostats.h b/include/linux/fs_iostats.h
new file mode 100644
index 000000000000..60d1efbea7d9
--- /dev/null
+++ b/include/linux/fs_iostats.h
@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_FS_IOSTATS_H
+#define _LINUX_FS_IOSTATS_H
+
+#include <linux/fs.h>
+#include <linux/percpu_counter.h>
+#include <linux/slab.h>
+
+/* Similar to task_io_accounting members */
+enum {
+ SB_IOSTATS_CHARS_RD, /* bytes read via syscalls */
+ SB_IOSTATS_CHARS_WR, /* bytes written via syscalls */
+ SB_IOSTATS_SYSCALLS_RD, /* # of read syscalls */
+ SB_IOSTATS_SYSCALLS_WR, /* # of write syscalls */
+ SB_IOSTATS_COUNTERS_NUM
+};
+
+struct sb_iostats {
+ time64_t start_time;
+ struct percpu_counter counter[SB_IOSTATS_COUNTERS_NUM];
+};
+
+#ifdef CONFIG_FS_IOSTATS
+static inline struct sb_iostats *sb_iostats(struct super_block *sb)
+{
+ return sb->s_iostats;
+}
+
+static inline bool sb_has_iostats(struct super_block *sb)
+{
+ return !!sb->s_iostats;
+}
+
+static inline void sb_iostats_destroy(struct super_block *sb)
+{
+ if (!sb->s_iostats)
+ return;
+
+ percpu_counters_destroy(sb->s_iostats->counter,
+ SB_IOSTATS_COUNTERS_NUM);
+ kfree(sb->s_iostats);
+ sb->s_iostats = NULL;
+}
+
+/* Initialize per-sb I/O stats */
+static inline int sb_iostats_init(struct super_block *sb)
+{
+ int err;
+
+ sb->s_iostats = kmalloc(sizeof(struct sb_iostats), GFP_KERNEL);
+ if (!sb->s_iostats)
+ return -ENOMEM;
+
+ err = percpu_counters_init(sb->s_iostats->counter,
+ SB_IOSTATS_COUNTERS_NUM, 0, GFP_KERNEL);
+ if (err) {
+ kfree(sb->s_iostats);
+ sb->s_iostats = NULL;
+ return err;
+ }
+
+ sb->s_iostats->start_time = ktime_get_seconds();
+ return 0;
+}
+
+static inline void sb_iostats_counter_inc(struct super_block *sb, int id)
+{
+ if (!sb->s_iostats)
+ return;
+
+ percpu_counter_inc(&sb->s_iostats->counter[id]);
+}
+
+static inline void sb_iostats_counter_add(struct super_block *sb, int id,
+ s64 amt)
+{
+ if (!sb->s_iostats)
+ return;
+
+ percpu_counter_add(&sb->s_iostats->counter[id], amt);
+}
+
+static inline s64 sb_iostats_counter_read(struct super_block *sb, int id)
+{
+ if (!sb->s_iostats)
+ return 0;
+
+ return percpu_counter_read_positive(&sb->s_iostats->counter[id]);
+}
+
+#else /* !CONFIG_FS_IOSTATS */
+
+static inline struct sb_iostats *sb_iostats(struct super_block *sb)
+{
+ return NULL;
+}
+
+static inline bool sb_has_iostats(struct super_block *sb)
+{
+ return false;
+}
+
+static inline int sb_iostats_init(struct super_block *sb)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline void sb_iostats_destroy(struct super_block *sb)
+{
+}
+
+static inline void sb_iostats_counter_inc(struct super_block *sb, int id)
+{
+}
+
+static inline void sb_iostats_counter_add(struct super_block *sb, int id,
+ s64 amt)
+{
+}
+
+static inline s64 sb_iostats_counter_read(struct super_block *sb, int id)
+{
+ return 0;
+}
+#endif
+
+#endif /* _LINUX_FS_IOSTATS_H */
--
2.25.1
