// SPDX-License-Identifier: GPL-2.0-or-later/* CacheFiles statistics * * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #include <linux/module.h>#include <linux/proc_fs.h>#include <linux/seq_file.h>#include "internal.h" atomic_t cachefiles_lookup_histogram[HZ];atomic_t cachefiles_mkdir_histogram[HZ];atomic_t cachefiles_create_histogram[HZ]; /* * display the latency histogram */static int cachefiles_histogram_show(struct seq_file *m, void *v){	unsigned long index;	unsigned x, y, z, t; 	switch ((unsigned long) v) {	case 1:		seq_puts(m, "JIFS  SECS  LOOKUPS   MKDIRS    CREATES\n");		return 0;	case 2:		seq_puts(m, "===== ===== ========= ========= =========\n");		return 0;	default:		index = (unsigned long) v - 3;		x = atomic_read(&cachefiles_lookup_histogram[index]);		y = atomic_read(&cachefiles_mkdir_histogram[index]);		z = atomic_read(&cachefiles_create_histogram[index]);		if (x == 0 && y == 0 && z == 0)			return 0; 		t = (index * 1000) / HZ; 		seq_printf(m, "%4lu  0.%03u %9u %9u %9u\n", index, t, x, y, z);		return 0;	}} /* * set up the iterator to start reading from the first line */static void *cachefiles_histogram_start(struct seq_file *m, loff_t *_pos){	if ((unsigned long long)*_pos >= HZ + 2)		return NULL;	if (*_pos == 0)		*_pos = 1;	return (void *)(unsigned long) *_pos;} /* * move to the next line */static void *cachefiles_histogram_next(struct seq_file *m, void *v, loff_t *pos){	(*pos)++;	return (unsigned long long)*pos > HZ + 2 ?		NULL : (void *)(unsigned long) *pos;} /* * clean up after reading */static void cachefiles_histogram_stop(struct seq_file *m, void *v){} static const struct seq_operations cachefiles_histogram_ops = {	.start		= cachefiles_histogram_start,	.stop		= cachefiles_histogram_stop,	.next		= cachefiles_histogram_next,	.show		= cachefiles_histogram_show,}; /* * initialise the /proc/fs/cachefiles/ directory */int __init cachefiles_proc_init(void){	_enter(""); 	if (!proc_mkdir("fs/cachefiles", NULL))		goto error_dir; 	if (!proc_create_seq("fs/cachefiles/histogram", S_IFREG | 0444, NULL,			 &cachefiles_histogram_ops))		goto error_histogram; 	_leave(" = 0");	return 0; error_histogram:	remove_proc_entry("fs/cachefiles", NULL);error_dir:	_leave(" = -ENOMEM");	return -ENOMEM;} /* * clean up the /proc/fs/cachefiles/ directory */void cachefiles_proc_cleanup(void){	remove_proc_entry("fs/cachefiles/histogram", NULL);	remove_proc_entry("fs/cachefiles", NULL);}