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Subject[RFC PATCH 48/76] fscache: Always create /proc/fs/fscache/stats if configured
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Split the fscache initialisation so that /proc/fs/fscache/stats is always
created, if FSCACHE_STATS=y, thereby allowing it to be used if the read
helper is enabled, but not the rest of the caching infrastructure.

Signed-off-by: David Howells <dhowells@redhat.com>
---

fs/fscache/Makefile | 3 +
fs/fscache/cache_init.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
fs/fscache/internal.h | 12 +++-
fs/fscache/main.c | 115 ++++-----------------------------------
fs/fscache/proc.c | 52 +-----------------
fs/fscache/stats.c | 8 +++
6 files changed, 174 insertions(+), 155 deletions(-)
create mode 100644 fs/fscache/cache_init.c

diff --git a/fs/fscache/Makefile b/fs/fscache/Makefile
index 3caf66810e7b..5d3284f6fe2d 100644
--- a/fs/fscache/Makefile
+++ b/fs/fscache/Makefile
@@ -5,6 +5,7 @@

fscache-y := \
cache.o \
+ cache_init.o \
cookie.o \
dispatcher.o \
fsdef.o \
@@ -15,8 +16,8 @@ fscache-y := \
object_bits.o

fscache-$(CONFIG_PROC_FS) += proc.o
-fscache-$(CONFIG_FSCACHE_STATS) += stats.o
fscache-$(CONFIG_FSCACHE_HISTOGRAM) += histogram.o
fscache-$(CONFIG_FSCACHE_OBJECT_LIST) += object-list.o
+fscache-$(CONFIG_FSCACHE_STATS) += stats.o

obj-$(CONFIG_FSCACHE) := fscache.o
diff --git a/fs/fscache/cache_init.c b/fs/fscache/cache_init.c
new file mode 100644
index 000000000000..8cade2e00050
--- /dev/null
+++ b/fs/fscache/cache_init.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* General filesystem local caching manager
+ *
+ * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL CACHE
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/completion.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#define CREATE_TRACE_POINTS
+#include "internal.h"
+
+struct kobject *fscache_root;
+struct workqueue_struct *fscache_op_wq;
+
+/* these values serve as lower bounds, will be adjusted in fscache_init() */
+static unsigned fscache_object_max_active = 4;
+static unsigned fscache_op_max_active = 2;
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table_header *fscache_sysctl_header;
+
+static int fscache_max_active_sysctl(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct workqueue_struct **wqp = table->extra1;
+ unsigned int *datap = table->data;
+ int ret;
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ if (ret == 0)
+ workqueue_set_max_active(*wqp, *datap);
+ return ret;
+}
+
+static struct ctl_table fscache_sysctls[] = {
+ {
+ .procname = "operation_max_active",
+ .data = &fscache_op_max_active,
+ .maxlen = sizeof(unsigned),
+ .mode = 0644,
+ .proc_handler = fscache_max_active_sysctl,
+ .extra1 = &fscache_op_wq,
+ },
+ {}
+};
+
+static struct ctl_table fscache_sysctls_root[] = {
+ {
+ .procname = "fscache",
+ .mode = 0555,
+ .child = fscache_sysctls,
+ },
+ {}
+};
+#endif
+
+/*
+ * Initialise the caching code.
+ */
+int __init fscache_init_caching(void)
+{
+ int ret;
+
+ fscache_op_max_active =
+ clamp_val(fscache_object_max_active / 2,
+ fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
+
+ ret = -ENOMEM;
+ fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
+ fscache_op_max_active);
+ if (!fscache_op_wq)
+ goto error_op_wq;
+
+ ret = fscache_init_dispatchers();
+ if (ret < 0)
+ goto error_dispatchers;
+
+ ret = fscache_proc_caching_init();
+ if (ret < 0)
+ goto error_proc;
+
+#ifdef CONFIG_SYSCTL
+ ret = -ENOMEM;
+ fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
+ if (!fscache_sysctl_header)
+ goto error_sysctl;
+#endif
+
+ fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
+ sizeof(struct fscache_cookie),
+ 0, 0, NULL);
+ if (!fscache_cookie_jar) {
+ pr_notice("Failed to allocate a cookie jar\n");
+ ret = -ENOMEM;
+ goto error_cookie_jar;
+ }
+
+ fscache_root = kobject_create_and_add("fscache", kernel_kobj);
+ if (!fscache_root)
+ goto error_kobj;
+
+ return 0;
+
+error_kobj:
+ kmem_cache_destroy(fscache_cookie_jar);
+error_cookie_jar:
+#ifdef CONFIG_SYSCTL
+ unregister_sysctl_table(fscache_sysctl_header);
+error_sysctl:
+#endif
+ fscache_kill_dispatchers();
+error_dispatchers:
+error_proc:
+ destroy_workqueue(fscache_op_wq);
+error_op_wq:
+ return ret;
+}
+
+/*
+ * clean up on module removal
+ */
+void __exit fscache_exit_caching(void)
+{
+ _enter("");
+
+ kobject_put(fscache_root);
+ kmem_cache_destroy(fscache_cookie_jar);
+#ifdef CONFIG_SYSCTL
+ unregister_sysctl_table(fscache_sysctl_header);
+#endif
+ fscache_kill_dispatchers();
+ destroy_workqueue(fscache_op_wq);
+}
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index ae05f636faac..1721823b8cac 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -56,6 +56,12 @@ static inline void fscache_put_cache_tag(struct fscache_cache_tag *tag)
kfree(tag);
}

+/*
+ * cache_init.c
+ */
+extern int __init fscache_init_caching(void);
+extern void __exit fscache_exit_caching(void);
+
/*
* cookie.c
*/
@@ -164,11 +170,9 @@ extern void fscache_objlist_remove(struct fscache_object *);
* proc.c
*/
#ifdef CONFIG_PROC_FS
-extern int __init fscache_proc_init(void);
-extern void fscache_proc_cleanup(void);
+extern int __init fscache_proc_caching_init(void);
#else
#define fscache_proc_init() (0)
-#define fscache_proc_cleanup() do {} while (0)
#endif

/*
@@ -230,11 +234,13 @@ static inline void fscache_stat_d(atomic_t *stat)
#define __fscache_stat(stat) (stat)

int fscache_stats_show(struct seq_file *m, void *v);
+extern int __init fscache_proc_stats_init(void);
#else

#define __fscache_stat(stat) (NULL)
#define fscache_stat(stat) do {} while (0)
#define fscache_stat_d(stat) do {} while (0)
+#define fscache_proc_stats_init(void) 0
#endif

static inline
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
index 003e53d17245..9bdcd9557aa6 100644
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -11,8 +11,7 @@
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
-#include <linux/seq_file.h>
-#define CREATE_TRACE_POINTS
+#include <linux/proc_fs.h>
#include "internal.h"

MODULE_DESCRIPTION("FS Cache Manager");
@@ -25,115 +24,31 @@ module_param_named(debug, fscache_debug, uint,
MODULE_PARM_DESC(fscache_debug,
"FS-Cache debugging mask");

-struct kobject *fscache_root;
-struct workqueue_struct *fscache_op_wq;
-
-/* these values serve as lower bounds, will be adjusted in fscache_init() */
-static unsigned fscache_object_max_active = 4;
-static unsigned fscache_op_max_active = 2;
-
-#ifdef CONFIG_SYSCTL
-static struct ctl_table_header *fscache_sysctl_header;
-
-static int fscache_max_active_sysctl(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
-{
- struct workqueue_struct **wqp = table->extra1;
- unsigned int *datap = table->data;
- int ret;
-
- ret = proc_dointvec(table, write, buffer, lenp, ppos);
- if (ret == 0)
- workqueue_set_max_active(*wqp, *datap);
- return ret;
-}
-
-static struct ctl_table fscache_sysctls[] = {
- {
- .procname = "operation_max_active",
- .data = &fscache_op_max_active,
- .maxlen = sizeof(unsigned),
- .mode = 0644,
- .proc_handler = fscache_max_active_sysctl,
- .extra1 = &fscache_op_wq,
- },
- {}
-};
-
-static struct ctl_table fscache_sysctls_root[] = {
- {
- .procname = "fscache",
- .mode = 0555,
- .child = fscache_sysctls,
- },
- {}
-};
-#endif
-
/*
- * initialise the fs caching module
+ * Initialise the module
*/
static int __init fscache_init(void)
{
int ret;

- fscache_op_max_active =
- clamp_val(fscache_object_max_active / 2,
- fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
-
- ret = -ENOMEM;
- fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
- fscache_op_max_active);
- if (!fscache_op_wq)
- goto error_op_wq;
+ if (!proc_mkdir("fs/fscache", NULL))
+ return -ENOMEM;

- ret = fscache_init_dispatchers();
+ ret = fscache_proc_stats_init();
if (ret < 0)
- goto error_dispatchers;
+ goto error;

- ret = fscache_proc_init();
+ ret = fscache_init_caching();
if (ret < 0)
- goto error_proc;
-
-#ifdef CONFIG_SYSCTL
- ret = -ENOMEM;
- fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
- if (!fscache_sysctl_header)
- goto error_sysctl;
-#endif
-
- fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
- sizeof(struct fscache_cookie),
- 0, 0, NULL);
- if (!fscache_cookie_jar) {
- pr_notice("Failed to allocate a cookie jar\n");
- ret = -ENOMEM;
- goto error_cookie_jar;
- }
-
- fscache_root = kobject_create_and_add("fscache", kernel_kobj);
- if (!fscache_root)
- goto error_kobj;
+ goto error;

pr_notice("Loaded\n");
return 0;

-error_kobj:
- kmem_cache_destroy(fscache_cookie_jar);
-error_cookie_jar:
-#ifdef CONFIG_SYSCTL
- unregister_sysctl_table(fscache_sysctl_header);
-error_sysctl:
-#endif
- fscache_kill_dispatchers();
-error_dispatchers:
- fscache_proc_cleanup();
-error_proc:
- destroy_workqueue(fscache_op_wq);
-error_op_wq:
+error:
+ remove_proc_subtree("fs/fscache", NULL);
return ret;
}
-
fs_initcall(fscache_init);

/*
@@ -143,14 +58,8 @@ static void __exit fscache_exit(void)
{
_enter("");

- kobject_put(fscache_root);
- kmem_cache_destroy(fscache_cookie_jar);
-#ifdef CONFIG_SYSCTL
- unregister_sysctl_table(fscache_sysctl_header);
-#endif
- fscache_proc_cleanup();
- fscache_kill_dispatchers();
- destroy_workqueue(fscache_op_wq);
+ remove_proc_subtree("fs/fscache", NULL);
+ fscache_exit_caching();
pr_notice("Unloaded\n");
}

diff --git a/fs/fscache/proc.c b/fs/fscache/proc.c
index 729d083f1e91..7e156b21bb1d 100644
--- a/fs/fscache/proc.c
+++ b/fs/fscache/proc.c
@@ -14,67 +14,23 @@
/*
* initialise the /proc/fs/fscache/ directory
*/
-int __init fscache_proc_init(void)
+int __init fscache_proc_caching_init(void)
{
- if (!proc_mkdir("fs/fscache", NULL))
- goto error_dir;
-
if (!proc_create_seq("fs/fscache/cookies", S_IFREG | 0444, NULL,
&fscache_cookies_seq_ops))
- goto error_cookies;
-
-#ifdef CONFIG_FSCACHE_STATS
- if (!proc_create_single("fs/fscache/stats", S_IFREG | 0444, NULL,
- fscache_stats_show))
- goto error_stats;
-#endif
+ return -ENOMEM;

#ifdef CONFIG_FSCACHE_HISTOGRAM
if (!proc_create_seq("fs/fscache/histogram", S_IFREG | 0444, NULL,
&fscache_histogram_ops))
- goto error_histogram;
+ return -ENOMEM;
#endif

#ifdef CONFIG_FSCACHE_OBJECT_LIST
if (!proc_create("fs/fscache/objects", S_IFREG | 0444, NULL,
&fscache_objlist_proc_ops))
- goto error_objects;
+ return -ENOMEM;
#endif

return 0;
-
-#ifdef CONFIG_FSCACHE_OBJECT_LIST
-error_objects:
-#endif
-#ifdef CONFIG_FSCACHE_HISTOGRAM
- remove_proc_entry("fs/fscache/histogram", NULL);
-error_histogram:
-#endif
-#ifdef CONFIG_FSCACHE_STATS
- remove_proc_entry("fs/fscache/stats", NULL);
-error_stats:
-#endif
- remove_proc_entry("fs/fscache/cookies", NULL);
-error_cookies:
- remove_proc_entry("fs/fscache", NULL);
-error_dir:
- return -ENOMEM;
-}
-
-/*
- * clean up the /proc/fs/fscache/ directory
- */
-void fscache_proc_cleanup(void)
-{
-#ifdef CONFIG_FSCACHE_OBJECT_LIST
- remove_proc_entry("fs/fscache/objects", NULL);
-#endif
-#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/cookies", NULL);
- remove_proc_entry("fs/fscache", NULL);
}
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index dffe6925aadb..bf2935571de5 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -115,3 +115,11 @@ int fscache_stats_show(struct seq_file *m, void *v)
atomic_read(&fscache_n_cache_culled_objects));
return 0;
}
+
+int __init fscache_proc_stats_init(void)
+{
+ if (!proc_create_single("fs/fscache/stats", S_IFREG | 0444, NULL,
+ fscache_stats_show))
+ return -ENOMEM;
+ return 0;
+}

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