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fscache: Introduce new driver

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Introduce basic skeleton of the new, rewritten fscache driver.

Changes
=======
ver #3:
 - Use remove_proc_subtree(), not remove_proc_entry() to remove a populated
   dir.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819584034.215744.4290533472390439030.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906887770.143852.3577888294989185666.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967080039.1823006.5702921801104057922.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021491014.640689.4292699878317589512.stgit@warthog.procyon.org.uk/ # v4
This commit is contained in:
David Howells 2021-10-20 14:34:41 +01:00
parent a39c41b853
commit 1e1236b841
10 changed files with 420 additions and 1 deletions
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1
fs/Makefile
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@ -67,6 +67,7 @@ obj-$(CONFIG_DLM) += dlm/
# Do not add any filesystems before this line
obj-$(CONFIG_NETFS_SUPPORT) += netfs/
obj-$(CONFIG_FSCACHE) += fscache/
obj-$(CONFIG_REISERFS_FS) += reiserfs/
obj-$(CONFIG_EXT4_FS) += ext4/
# We place ext4 before ext2 so that clean ext3 root fs's do NOT mount using the

39
fs/fscache/Kconfig
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@ -1,4 +1,43 @@
# SPDX-License-Identifier: GPL-2.0-only
config FSCACHE
tristate "General filesystem local caching manager"
select NETFS_SUPPORT
help
This option enables a generic filesystem caching manager that can be
used by various network and other filesystems to cache data locally.
Different sorts of caches can be plugged in, depending on the
resources available.
See Documentation/filesystems/caching/fscache.rst for more information.
config FSCACHE_STATS
bool "Gather statistical information on local caching"
depends on FSCACHE && PROC_FS
select NETFS_STATS
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.rst for more information.
config FSCACHE_DEBUG
bool "Debug FS-Cache"
depends on FSCACHE
help
This permits debugging to be dynamically enabled in the local caching
management module. If this is set, the debugging output may be
enabled by setting bits in /sys/modules/fscache/parameter/debug.
See Documentation/filesystems/caching/fscache.rst for more information.
config FSCACHE_OLD_API
bool

12
fs/fscache/Makefile Normal file
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@ -0,0 +1,12 @@
# SPDX-License-Identifier: GPL-2.0
#
# Makefile for general filesystem caching code
#
fscache-y := \
main.o
fscache-$(CONFIG_PROC_FS) += proc.o
fscache-$(CONFIG_FSCACHE_STATS) += stats.o
obj-$(CONFIG_FSCACHE) := fscache.o

183
fs/fscache/internal.h Normal file
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@ -0,0 +1,183 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Internal definitions for FS-Cache
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#ifdef pr_fmt
#undef pr_fmt
#endif
#define pr_fmt(fmt) "FS-Cache: " fmt
#include <linux/slab.h>
#include <linux/fscache-cache.h>
#include <trace/events/fscache.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
/*
* main.c
*/
extern unsigned fscache_debug;
/*
* 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
/*
* stats.c
*/
#ifdef CONFIG_FSCACHE_STATS
static inline void fscache_stat(atomic_t *stat)
{
atomic_inc(stat);
}
static inline void fscache_stat_d(atomic_t *stat)
{
atomic_dec(stat);
}
#define __fscache_stat(stat) (stat)
int fscache_stats_show(struct seq_file *m, void *v);
#else
#define __fscache_stat(stat) (NULL)
#define fscache_stat(stat) do {} while (0)
#define fscache_stat_d(stat) do {} while (0)
#endif
/*****************************************************************************/
/*
* debug tracing
*/
#define dbgprintk(FMT, ...) \
printk("[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
#define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)
#define kjournal(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
#ifdef __KDEBUG
#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)
#elif defined(CONFIG_FSCACHE_DEBUG)
#define _enter(FMT, ...) \
do { \
if (__do_kdebug(ENTER)) \
kenter(FMT, ##__VA_ARGS__); \
} while (0)
#define _leave(FMT, ...) \
do { \
if (__do_kdebug(LEAVE)) \
kleave(FMT, ##__VA_ARGS__); \
} while (0)
#define _debug(FMT, ...) \
do { \
if (__do_kdebug(DEBUG)) \
kdebug(FMT, ##__VA_ARGS__); \
} while (0)
#else
#define _enter(FMT, ...) no_printk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define _leave(FMT, ...) no_printk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define _debug(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
#endif
/*
* determine whether a particular optional debugging point should be logged
* - we need to go through three steps to persuade cpp to correctly join the
* shorthand in FSCACHE_DEBUG_LEVEL with its prefix
*/
#define ____do_kdebug(LEVEL, POINT) \
unlikely((fscache_debug & \
(FSCACHE_POINT_##POINT << (FSCACHE_DEBUG_ ## LEVEL * 3))))
#define ___do_kdebug(LEVEL, POINT) \
____do_kdebug(LEVEL, POINT)
#define __do_kdebug(POINT) \
___do_kdebug(FSCACHE_DEBUG_LEVEL, POINT)
#define FSCACHE_DEBUG_CACHE 0
#define FSCACHE_DEBUG_COOKIE 1
#define FSCACHE_DEBUG_OBJECT 2
#define FSCACHE_DEBUG_OPERATION 3
#define FSCACHE_POINT_ENTER 1
#define FSCACHE_POINT_LEAVE 2
#define FSCACHE_POINT_DEBUG 4
#ifndef FSCACHE_DEBUG_LEVEL
#define FSCACHE_DEBUG_LEVEL CACHE
#endif
/*
* assertions
*/
#if 1 /* defined(__KDEBUGALL) */
#define ASSERT(X) \
do { \
if (unlikely(!(X))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTCMP(X, OP, Y) \
do { \
if (unlikely(!((X) OP (Y)))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
pr_err("%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#define ASSERTIF(C, X) \
do { \
if (unlikely((C) && !(X))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTIFCMP(C, X, OP, Y) \
do { \
if (unlikely((C) && !((X) OP (Y)))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
pr_err("%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#else
#define ASSERT(X) do {} while (0)
#define ASSERTCMP(X, OP, Y) do {} while (0)
#define ASSERTIF(C, X) do {} while (0)
#define ASSERTIFCMP(C, X, OP, Y) do {} while (0)
#endif /* assert or not */

65
fs/fscache/main.c Normal file
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@ -0,0 +1,65 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/* General filesystem local caching manager
*
* Copyright (C) 2021 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>
#define CREATE_TRACE_POINTS
#include "internal.h"
MODULE_DESCRIPTION("FS Cache Manager");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");
unsigned fscache_debug;
module_param_named(debug, fscache_debug, uint,
S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(fscache_debug,
"FS-Cache debugging mask");
struct workqueue_struct *fscache_wq;
EXPORT_SYMBOL(fscache_wq);
/*
* initialise the fs caching module
*/
static int __init fscache_init(void)
{
int ret = -ENOMEM;
fscache_wq = alloc_workqueue("fscache", WQ_UNBOUND | WQ_FREEZABLE, 0);
if (!fscache_wq)
goto error_wq;
ret = fscache_proc_init();
if (ret < 0)
goto error_proc;
pr_notice("Loaded\n");
return 0;
error_proc:
destroy_workqueue(fscache_wq);
error_wq:
return ret;
}
fs_initcall(fscache_init);
/*
* clean up on module removal
*/
static void __exit fscache_exit(void)
{
_enter("");
fscache_proc_cleanup();
destroy_workqueue(fscache_wq);
pr_notice("Unloaded\n");
}
module_exit(fscache_exit);

42
fs/fscache/proc.c Normal file
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@ -0,0 +1,42 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/* FS-Cache statistics viewing interface
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#define FSCACHE_DEBUG_LEVEL CACHE
#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)
{
if (!proc_mkdir("fs/fscache", NULL))
goto error_dir;
#ifdef CONFIG_FSCACHE_STATS
if (!proc_create_single("fs/fscache/stats", S_IFREG | 0444, NULL,
fscache_stats_show))
goto error;
#endif
return 0;
error:
remove_proc_entry("fs/fscache", NULL);
error_dir:
return -ENOMEM;
}
/*
* clean up the /proc/fs/fscache/ directory
*/
void fscache_proc_cleanup(void)
{
remove_proc_subtree("fs/fscache", NULL);
}

22
fs/fscache/stats.c Normal file
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@ -0,0 +1,22 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/* FS-Cache statistics
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#define FSCACHE_DEBUG_LEVEL CACHE
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "internal.h"
/*
* display the general statistics
*/
int fscache_stats_show(struct seq_file *m, void *v)
{
seq_puts(m, "FS-Cache statistics\n");
netfs_stats_show(m);
return 0;
}

2
include/linux/fscache-cache.h
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@ -16,4 +16,6 @@
#include <linux/fscache.h>
extern struct workqueue_struct *fscache_wq;
#endif /* _LINUX_FSCACHE_CACHE_H */

6
include/linux/fscache.h
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@ -1,7 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
/* General filesystem caching interface
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* NOTE!!! See:
@ -18,9 +18,13 @@
#include <linux/netfs.h>
#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
#define __fscache_available (1)
#define fscache_available() (1)
#define fscache_cookie_valid(cookie) (cookie)
#define fscache_cookie_enabled(cookie) (cookie)
#else
#define __fscache_available (0)
#define fscache_available() (0)
#define fscache_cookie_valid(cookie) (0)
#define fscache_cookie_enabled(cookie) (0)
#endif

49
include/trace/events/fscache.h Normal file
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@ -0,0 +1,49 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
/* FS-Cache tracepoints
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#undef TRACE_SYSTEM
#define TRACE_SYSTEM fscache
#if !defined(_TRACE_FSCACHE_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_FSCACHE_H
#include <linux/fscache.h>
#include <linux/tracepoint.h>
/*
* Define enums for tracing information.
*/
#ifndef __FSCACHE_DECLARE_TRACE_ENUMS_ONCE_ONLY
#define __FSCACHE_DECLARE_TRACE_ENUMS_ONCE_ONLY
#endif
/*
* Declare tracing information enums and their string mappings for display.
*/
/*
* Export enum symbols via userspace.
*/
#undef EM
#undef E_
#define EM(a, b) TRACE_DEFINE_ENUM(a);
#define E_(a, b) TRACE_DEFINE_ENUM(a);
/*
* Now redefine the EM() and E_() macros to map the enums to the strings that
* will be printed in the output.
*/
#undef EM
#undef E_
#define EM(a, b) { a, b },
#define E_(a, b) { a, b }
#endif /* _TRACE_FSCACHE_H */
/* This part must be outside protection */
#include <trace/define_trace.h>