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FS-Cache: Add use of /proc and presentation of statistics

Make FS-Cache create its /proc interface and present various statistical
information through it.  Also provide the functions for updating this
information.

These features are enabled by:

	CONFIG_FSCACHE_PROC
	CONFIG_FSCACHE_STATS
	CONFIG_FSCACHE_HISTOGRAM

The /proc directory for FS-Cache is also exported so that caching modules can
add their own statistics there too.

The FS-Cache module is loadable at this point, and the statistics files can be
examined by userspace:

	cat /proc/fs/fscache/stats
	cat /proc/fs/fscache/histogram

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
This commit is contained in:
David Howells 2009-04-03 16:42:37 +01:00
parent 06b3db1b9b
commit 7394daa8c6
10 changed files with 566 additions and 17 deletions

View File

@ -100,12 +100,6 @@ A sysfs directory called /sys/fs/fscache/<cachetag>/ is created if CONFIG_SYSFS
is enabled. This is accessible through the kobject struct fscache_cache::kobj
and is for use by the cache as it sees fit.
The cache driver may create itself a directory named for the cache type in the
/proc/fs/fscache/ directory. This is available if CONFIG_FSCACHE_PROC is
enabled and is accessible through:
struct proc_dir_entry *proc_fscache;
========================
RELEVANT DATA STRUCTURES

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@ -195,7 +195,6 @@ STATISTICAL INFORMATION
If FS-Cache is compiled with the following options enabled:
CONFIG_FSCACHE_PROC=y (implied by the following two)
CONFIG_FSCACHE_STATS=y
CONFIG_FSCACHE_HISTOGRAM=y
@ -275,7 +274,7 @@ proc files.
(*) /proc/fs/fscache/histogram
cat /proc/fs/fscache/histogram
+HZ +TIME OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS
JIFS SECS OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS
===== ===== ========= ========= ========= ========= =========
This shows the breakdown of the number of times each amount of time
@ -291,16 +290,16 @@ proc files.
RETRIEVLS Time between beginning and end of a retrieval
Each row shows the number of events that took a particular range of times.
Each step is 1 jiffy in size. The +HZ column indicates the particular
jiffy range covered, and the +TIME field the equivalent number of seconds.
Each step is 1 jiffy in size. The JIFS column indicates the particular
jiffy range covered, and the SECS field the equivalent number of seconds.
=========
DEBUGGING
=========
The FS-Cache facility can have runtime debugging enabled by adjusting the value
in:
If CONFIG_FSCACHE_DEBUG is enabled, the FS-Cache facility can have runtime
debugging enabled by adjusting the value in:
/sys/module/fscache/parameters/debug
@ -327,4 +326,3 @@ the control file. For example:
echo $((1|8|64)) >/sys/module/fscache/parameters/debug
will turn on all function entry debugging.

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@ -11,6 +11,40 @@ config FSCACHE
See Documentation/filesystems/caching/fscache.txt for more information.
config FSCACHE_STATS
bool "Gather statistical information on local caching"
depends on FSCACHE && PROC_FS
help
This option causes statistical information to be gathered on local
caching and exported through file:
/proc/fs/fscache/stats
The gathering of statistics adds a certain amount of overhead to
execution as there are a quite a few stats gathered, and on a
multi-CPU system these may be on cachelines that keep bouncing
between CPUs. On the other hand, the stats are very useful for
debugging purposes. Saying 'Y' here is recommended.
See Documentation/filesystems/caching/fscache.txt for more information.
config FSCACHE_HISTOGRAM
bool "Gather latency information on local caching"
depends on FSCACHE && PROC_FS
help
This option causes latency information to be gathered on local
caching and exported through file:
/proc/fs/fscache/histogram
The generation of this histogram adds a certain amount of overhead to
execution as there are a number of points at which data is gathered,
and on a multi-CPU system these may be on cachelines that keep
bouncing between CPUs. On the other hand, the histogram may be
useful for debugging purposes. Saying 'N' here is recommended.
See Documentation/filesystems/caching/fscache.txt for more information.
config FSCACHE_DEBUG
bool "Debug FS-Cache"
depends on FSCACHE

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@ -5,4 +5,8 @@
fscache-y := \
main.o
fscache-$(CONFIG_PROC_FS) += proc.o
fscache-$(CONFIG_FSCACHE_STATS) += stats.o
fscache-$(CONFIG_FSCACHE_HISTOGRAM) += histogram.o
obj-$(CONFIG_FSCACHE) := fscache.o

109
fs/fscache/histogram.c Normal file
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@ -0,0 +1,109 @@
/* FS-Cache latency histogram
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL THREAD
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
atomic_t fscache_obj_instantiate_histogram[HZ];
atomic_t fscache_objs_histogram[HZ];
atomic_t fscache_ops_histogram[HZ];
atomic_t fscache_retrieval_delay_histogram[HZ];
atomic_t fscache_retrieval_histogram[HZ];
/*
* display the time-taken histogram
*/
static int fscache_histogram_show(struct seq_file *m, void *v)
{
unsigned long index;
unsigned n[5], t;
switch ((unsigned long) v) {
case 1:
seq_puts(m, "JIFS SECS OBJ INST OP RUNS OBJ RUNS "
" RETRV DLY RETRIEVLS\n");
return 0;
case 2:
seq_puts(m, "===== ===== ========= ========= ========="
" ========= =========\n");
return 0;
default:
index = (unsigned long) v - 3;
n[0] = atomic_read(&fscache_obj_instantiate_histogram[index]);
n[1] = atomic_read(&fscache_ops_histogram[index]);
n[2] = atomic_read(&fscache_objs_histogram[index]);
n[3] = atomic_read(&fscache_retrieval_delay_histogram[index]);
n[4] = atomic_read(&fscache_retrieval_histogram[index]);
if (!(n[0] | n[1] | n[2] | n[3] | n[4]))
return 0;
t = (index * 1000) / HZ;
seq_printf(m, "%4lu 0.%03u %9u %9u %9u %9u %9u\n",
index, t, n[0], n[1], n[2], n[3], n[4]);
return 0;
}
}
/*
* set up the iterator to start reading from the first line
*/
static void *fscache_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 *fscache_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 fscache_histogram_stop(struct seq_file *m, void *v)
{
}
static const struct seq_operations fscache_histogram_ops = {
.start = fscache_histogram_start,
.stop = fscache_histogram_stop,
.next = fscache_histogram_next,
.show = fscache_histogram_show,
};
/*
* open "/proc/fs/fscache/histogram" to provide latency data
*/
static int fscache_histogram_open(struct inode *inode, struct file *file)
{
return seq_open(file, &fscache_histogram_ops);
}
const struct file_operations fscache_histogram_fops = {
.owner = THIS_MODULE,
.open = fscache_histogram_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};

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@ -27,6 +27,30 @@
#define FSCACHE_MIN_THREADS 4
#define FSCACHE_MAX_THREADS 32
/*
* fsc-histogram.c
*/
#ifdef CONFIG_FSCACHE_HISTOGRAM
extern atomic_t fscache_obj_instantiate_histogram[HZ];
extern atomic_t fscache_objs_histogram[HZ];
extern atomic_t fscache_ops_histogram[HZ];
extern atomic_t fscache_retrieval_delay_histogram[HZ];
extern atomic_t fscache_retrieval_histogram[HZ];
static inline void fscache_hist(atomic_t histogram[], unsigned long start_jif)
{
unsigned long jif = jiffies - start_jif;
if (jif >= HZ)
jif = HZ - 1;
atomic_inc(&histogram[jif]);
}
extern const struct file_operations fscache_histogram_fops;
#else
#define fscache_hist(hist, start_jif) do {} while (0)
#endif
/*
* fsc-main.c
*/
@ -35,6 +59,109 @@ extern unsigned fscache_defer_create;
extern unsigned fscache_debug;
extern struct kobject *fscache_root;
/*
* fsc-proc.c
*/
#ifdef CONFIG_PROC_FS
extern int __init fscache_proc_init(void);
extern void fscache_proc_cleanup(void);
#else
#define fscache_proc_init() (0)
#define fscache_proc_cleanup() do {} while (0)
#endif
/*
* fsc-stats.c
*/
#ifdef CONFIG_FSCACHE_STATS
extern atomic_t fscache_n_ops_processed[FSCACHE_MAX_THREADS];
extern atomic_t fscache_n_objs_processed[FSCACHE_MAX_THREADS];
extern atomic_t fscache_n_op_pend;
extern atomic_t fscache_n_op_run;
extern atomic_t fscache_n_op_enqueue;
extern atomic_t fscache_n_op_deferred_release;
extern atomic_t fscache_n_op_release;
extern atomic_t fscache_n_op_gc;
extern atomic_t fscache_n_attr_changed;
extern atomic_t fscache_n_attr_changed_ok;
extern atomic_t fscache_n_attr_changed_nobufs;
extern atomic_t fscache_n_attr_changed_nomem;
extern atomic_t fscache_n_attr_changed_calls;
extern atomic_t fscache_n_allocs;
extern atomic_t fscache_n_allocs_ok;
extern atomic_t fscache_n_allocs_wait;
extern atomic_t fscache_n_allocs_nobufs;
extern atomic_t fscache_n_alloc_ops;
extern atomic_t fscache_n_alloc_op_waits;
extern atomic_t fscache_n_retrievals;
extern atomic_t fscache_n_retrievals_ok;
extern atomic_t fscache_n_retrievals_wait;
extern atomic_t fscache_n_retrievals_nodata;
extern atomic_t fscache_n_retrievals_nobufs;
extern atomic_t fscache_n_retrievals_intr;
extern atomic_t fscache_n_retrievals_nomem;
extern atomic_t fscache_n_retrieval_ops;
extern atomic_t fscache_n_retrieval_op_waits;
extern atomic_t fscache_n_stores;
extern atomic_t fscache_n_stores_ok;
extern atomic_t fscache_n_stores_again;
extern atomic_t fscache_n_stores_nobufs;
extern atomic_t fscache_n_stores_oom;
extern atomic_t fscache_n_store_ops;
extern atomic_t fscache_n_store_calls;
extern atomic_t fscache_n_marks;
extern atomic_t fscache_n_uncaches;
extern atomic_t fscache_n_acquires;
extern atomic_t fscache_n_acquires_null;
extern atomic_t fscache_n_acquires_no_cache;
extern atomic_t fscache_n_acquires_ok;
extern atomic_t fscache_n_acquires_nobufs;
extern atomic_t fscache_n_acquires_oom;
extern atomic_t fscache_n_updates;
extern atomic_t fscache_n_updates_null;
extern atomic_t fscache_n_updates_run;
extern atomic_t fscache_n_relinquishes;
extern atomic_t fscache_n_relinquishes_null;
extern atomic_t fscache_n_relinquishes_waitcrt;
extern atomic_t fscache_n_cookie_index;
extern atomic_t fscache_n_cookie_data;
extern atomic_t fscache_n_cookie_special;
extern atomic_t fscache_n_object_alloc;
extern atomic_t fscache_n_object_no_alloc;
extern atomic_t fscache_n_object_lookups;
extern atomic_t fscache_n_object_lookups_negative;
extern atomic_t fscache_n_object_lookups_positive;
extern atomic_t fscache_n_object_created;
extern atomic_t fscache_n_object_avail;
extern atomic_t fscache_n_object_dead;
extern atomic_t fscache_n_checkaux_none;
extern atomic_t fscache_n_checkaux_okay;
extern atomic_t fscache_n_checkaux_update;
extern atomic_t fscache_n_checkaux_obsolete;
static inline void fscache_stat(atomic_t *stat)
{
atomic_inc(stat);
}
extern const struct file_operations fscache_stats_fops;
#else
#define fscache_stat(stat) do {} while (0)
#endif
/*****************************************************************************/
/*
* debug tracing

View File

@ -52,9 +52,15 @@ static int __init fscache_init(void)
if (ret < 0)
goto error_slow_work;
ret = fscache_proc_init();
if (ret < 0)
goto error_proc;
printk(KERN_NOTICE "FS-Cache: Loaded\n");
return 0;
error_proc:
slow_work_unregister_user();
error_slow_work:
return ret;
}
@ -68,6 +74,7 @@ static void __exit fscache_exit(void)
{
_enter("");
fscache_proc_cleanup();
slow_work_unregister_user();
printk(KERN_NOTICE "FS-Cache: Unloaded\n");
}

68
fs/fscache/proc.c Normal file
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@ -0,0 +1,68 @@
/* FS-Cache statistics viewing interface
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL OPERATION
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
/*
* initialise the /proc/fs/fscache/ directory
*/
int __init fscache_proc_init(void)
{
_enter("");
if (!proc_mkdir("fs/fscache", NULL))
goto error_dir;
#ifdef CONFIG_FSCACHE_STATS
if (!proc_create("fs/fscache/stats", S_IFREG | 0444, NULL,
&fscache_stats_fops))
goto error_stats;
#endif
#ifdef CONFIG_FSCACHE_HISTOGRAM
if (!proc_create("fs/fscache/histogram", S_IFREG | 0444, NULL,
&fscache_histogram_fops))
goto error_histogram;
#endif
_leave(" = 0");
return 0;
#ifdef CONFIG_FSCACHE_HISTOGRAM
error_histogram:
#endif
#ifdef CONFIG_FSCACHE_STATS
remove_proc_entry("fs/fscache/stats", NULL);
error_stats:
#endif
remove_proc_entry("fs/fscache", NULL);
error_dir:
_leave(" = -ENOMEM");
return -ENOMEM;
}
/*
* clean up the /proc/fs/fscache/ directory
*/
void fscache_proc_cleanup(void)
{
#ifdef CONFIG_FSCACHE_HISTOGRAM
remove_proc_entry("fs/fscache/histogram", NULL);
#endif
#ifdef CONFIG_FSCACHE_STATS
remove_proc_entry("fs/fscache/stats", NULL);
#endif
remove_proc_entry("fs/fscache", NULL);
}

212
fs/fscache/stats.c Normal file
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@ -0,0 +1,212 @@
/* FS-Cache statistics
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL THREAD
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
/*
* operation counters
*/
atomic_t fscache_n_op_pend;
atomic_t fscache_n_op_run;
atomic_t fscache_n_op_enqueue;
atomic_t fscache_n_op_requeue;
atomic_t fscache_n_op_deferred_release;
atomic_t fscache_n_op_release;
atomic_t fscache_n_op_gc;
atomic_t fscache_n_attr_changed;
atomic_t fscache_n_attr_changed_ok;
atomic_t fscache_n_attr_changed_nobufs;
atomic_t fscache_n_attr_changed_nomem;
atomic_t fscache_n_attr_changed_calls;
atomic_t fscache_n_allocs;
atomic_t fscache_n_allocs_ok;
atomic_t fscache_n_allocs_wait;
atomic_t fscache_n_allocs_nobufs;
atomic_t fscache_n_alloc_ops;
atomic_t fscache_n_alloc_op_waits;
atomic_t fscache_n_retrievals;
atomic_t fscache_n_retrievals_ok;
atomic_t fscache_n_retrievals_wait;
atomic_t fscache_n_retrievals_nodata;
atomic_t fscache_n_retrievals_nobufs;
atomic_t fscache_n_retrievals_intr;
atomic_t fscache_n_retrievals_nomem;
atomic_t fscache_n_retrieval_ops;
atomic_t fscache_n_retrieval_op_waits;
atomic_t fscache_n_stores;
atomic_t fscache_n_stores_ok;
atomic_t fscache_n_stores_again;
atomic_t fscache_n_stores_nobufs;
atomic_t fscache_n_stores_oom;
atomic_t fscache_n_store_ops;
atomic_t fscache_n_store_calls;
atomic_t fscache_n_marks;
atomic_t fscache_n_uncaches;
atomic_t fscache_n_acquires;
atomic_t fscache_n_acquires_null;
atomic_t fscache_n_acquires_no_cache;
atomic_t fscache_n_acquires_ok;
atomic_t fscache_n_acquires_nobufs;
atomic_t fscache_n_acquires_oom;
atomic_t fscache_n_updates;
atomic_t fscache_n_updates_null;
atomic_t fscache_n_updates_run;
atomic_t fscache_n_relinquishes;
atomic_t fscache_n_relinquishes_null;
atomic_t fscache_n_relinquishes_waitcrt;
atomic_t fscache_n_cookie_index;
atomic_t fscache_n_cookie_data;
atomic_t fscache_n_cookie_special;
atomic_t fscache_n_object_alloc;
atomic_t fscache_n_object_no_alloc;
atomic_t fscache_n_object_lookups;
atomic_t fscache_n_object_lookups_negative;
atomic_t fscache_n_object_lookups_positive;
atomic_t fscache_n_object_created;
atomic_t fscache_n_object_avail;
atomic_t fscache_n_object_dead;
atomic_t fscache_n_checkaux_none;
atomic_t fscache_n_checkaux_okay;
atomic_t fscache_n_checkaux_update;
atomic_t fscache_n_checkaux_obsolete;
/*
* display the general statistics
*/
static int fscache_stats_show(struct seq_file *m, void *v)
{
seq_puts(m, "FS-Cache statistics\n");
seq_printf(m, "Cookies: idx=%u dat=%u spc=%u\n",
atomic_read(&fscache_n_cookie_index),
atomic_read(&fscache_n_cookie_data),
atomic_read(&fscache_n_cookie_special));
seq_printf(m, "Objects: alc=%u nal=%u avl=%u ded=%u\n",
atomic_read(&fscache_n_object_alloc),
atomic_read(&fscache_n_object_no_alloc),
atomic_read(&fscache_n_object_avail),
atomic_read(&fscache_n_object_dead));
seq_printf(m, "ChkAux : non=%u ok=%u upd=%u obs=%u\n",
atomic_read(&fscache_n_checkaux_none),
atomic_read(&fscache_n_checkaux_okay),
atomic_read(&fscache_n_checkaux_update),
atomic_read(&fscache_n_checkaux_obsolete));
seq_printf(m, "Pages : mrk=%u unc=%u\n",
atomic_read(&fscache_n_marks),
atomic_read(&fscache_n_uncaches));
seq_printf(m, "Acquire: n=%u nul=%u noc=%u ok=%u nbf=%u"
" oom=%u\n",
atomic_read(&fscache_n_acquires),
atomic_read(&fscache_n_acquires_null),
atomic_read(&fscache_n_acquires_no_cache),
atomic_read(&fscache_n_acquires_ok),
atomic_read(&fscache_n_acquires_nobufs),
atomic_read(&fscache_n_acquires_oom));
seq_printf(m, "Lookups: n=%u neg=%u pos=%u crt=%u\n",
atomic_read(&fscache_n_object_lookups),
atomic_read(&fscache_n_object_lookups_negative),
atomic_read(&fscache_n_object_lookups_positive),
atomic_read(&fscache_n_object_created));
seq_printf(m, "Updates: n=%u nul=%u run=%u\n",
atomic_read(&fscache_n_updates),
atomic_read(&fscache_n_updates_null),
atomic_read(&fscache_n_updates_run));
seq_printf(m, "Relinqs: n=%u nul=%u wcr=%u\n",
atomic_read(&fscache_n_relinquishes),
atomic_read(&fscache_n_relinquishes_null),
atomic_read(&fscache_n_relinquishes_waitcrt));
seq_printf(m, "AttrChg: n=%u ok=%u nbf=%u oom=%u run=%u\n",
atomic_read(&fscache_n_attr_changed),
atomic_read(&fscache_n_attr_changed_ok),
atomic_read(&fscache_n_attr_changed_nobufs),
atomic_read(&fscache_n_attr_changed_nomem),
atomic_read(&fscache_n_attr_changed_calls));
seq_printf(m, "Allocs : n=%u ok=%u wt=%u nbf=%u\n",
atomic_read(&fscache_n_allocs),
atomic_read(&fscache_n_allocs_ok),
atomic_read(&fscache_n_allocs_wait),
atomic_read(&fscache_n_allocs_nobufs));
seq_printf(m, "Allocs : ops=%u owt=%u\n",
atomic_read(&fscache_n_alloc_ops),
atomic_read(&fscache_n_alloc_op_waits));
seq_printf(m, "Retrvls: n=%u ok=%u wt=%u nod=%u nbf=%u"
" int=%u oom=%u\n",
atomic_read(&fscache_n_retrievals),
atomic_read(&fscache_n_retrievals_ok),
atomic_read(&fscache_n_retrievals_wait),
atomic_read(&fscache_n_retrievals_nodata),
atomic_read(&fscache_n_retrievals_nobufs),
atomic_read(&fscache_n_retrievals_intr),
atomic_read(&fscache_n_retrievals_nomem));
seq_printf(m, "Retrvls: ops=%u owt=%u\n",
atomic_read(&fscache_n_retrieval_ops),
atomic_read(&fscache_n_retrieval_op_waits));
seq_printf(m, "Stores : n=%u ok=%u agn=%u nbf=%u oom=%u\n",
atomic_read(&fscache_n_stores),
atomic_read(&fscache_n_stores_ok),
atomic_read(&fscache_n_stores_again),
atomic_read(&fscache_n_stores_nobufs),
atomic_read(&fscache_n_stores_oom));
seq_printf(m, "Stores : ops=%u run=%u\n",
atomic_read(&fscache_n_store_ops),
atomic_read(&fscache_n_store_calls));
seq_printf(m, "Ops : pend=%u run=%u enq=%u\n",
atomic_read(&fscache_n_op_pend),
atomic_read(&fscache_n_op_run),
atomic_read(&fscache_n_op_enqueue));
seq_printf(m, "Ops : dfr=%u rel=%u gc=%u\n",
atomic_read(&fscache_n_op_deferred_release),
atomic_read(&fscache_n_op_release),
atomic_read(&fscache_n_op_gc));
return 0;
}
/*
* open "/proc/fs/fscache/stats" allowing provision of a statistical summary
*/
static int fscache_stats_open(struct inode *inode, struct file *file)
{
return single_open(file, fscache_stats_show, NULL);
}
const struct file_operations fscache_stats_fops = {
.owner = THIS_MODULE,
.open = fscache_stats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};

View File

@ -29,10 +29,6 @@ struct fscache_cache_ops;
struct fscache_object;
struct fscache_operation;
#ifdef CONFIG_FSCACHE_PROC
extern struct proc_dir_entry *proc_fscache;
#endif
/*
* cache tag definition
*/