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>
diff --git a/fs/fscache/Kconfig b/fs/fscache/Kconfig
index 7c7bccd..9bbb8ce 100644
--- a/fs/fscache/Kconfig
+++ b/fs/fscache/Kconfig
@@ -11,6 +11,40 @@
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
diff --git a/fs/fscache/Makefile b/fs/fscache/Makefile
index f8038b8..1384823 100644
--- a/fs/fscache/Makefile
+++ b/fs/fscache/Makefile
@@ -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
diff --git a/fs/fscache/histogram.c b/fs/fscache/histogram.c
new file mode 100644
index 0000000..bad4967
--- /dev/null
+++ b/fs/fscache/histogram.c
@@ -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,
+};
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 95dc92d..16f9f1f4 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -28,6 +28,30 @@
#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
*/
extern unsigned fscache_defer_lookup;
@@ -35,6 +59,109 @@
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
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
index 76f7c69..7c734b7 100644
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -52,9 +52,15 @@
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 @@
{
_enter("");
+ fscache_proc_cleanup();
slow_work_unregister_user();
printk(KERN_NOTICE "FS-Cache: Unloaded\n");
}
diff --git a/fs/fscache/proc.c b/fs/fscache/proc.c
new file mode 100644
index 0000000..beeab44
--- /dev/null
+++ b/fs/fscache/proc.c
@@ -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);
+}
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
new file mode 100644
index 0000000..65deb99
--- /dev/null
+++ b/fs/fscache/stats.c
@@ -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,
+};