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cachefiles: Add some error injection support

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Add support for injecting ENOSPC or EIO errors.  This needs to be enabled
by CONFIG_CACHEFILES_ERROR_INJECTION=y.  Once enabled, ENOSPC on things
like write and mkdir can be triggered by:

        echo 1 >/proc/sys/cachefiles/error_injection

and EIO can be triggered on most operations by:

        echo 2 >/proc/sys/cachefiles/error_injection

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/163819624706.215744.6911916249119962943.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906925343.143852.5465695512984025812.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967134412.1823006.7354285948280296595.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021532340.640689.18209494225772443698.stgit@warthog.procyon.org.uk/ # v4
This commit is contained in:
David Howells 2021-10-21 08:15:26 +01:00
parent 8390fbc465
commit a70f652626
5 changed files with 108 additions and 1 deletions
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7
fs/cachefiles/Kconfig
View file

@ -19,3 +19,10 @@ config CACHEFILES_DEBUG
caching on files module. If this is set, the debugging output may be
enabled by setting bits in /sys/modules/cachefiles/parameter/debug or
by including a debugging specifier in /etc/cachefilesd.conf.
config CACHEFILES_ERROR_INJECTION
bool "Provide error injection for cachefiles"
depends on CACHEFILES && SYSCTL
help
This permits error injection to be enabled in cachefiles whilst a
cache is in service.

2
fs/cachefiles/Makefile
View file

@ -6,4 +6,6 @@
cachefiles-y := \
main.o
cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o
obj-$(CONFIG_CACHEFILES) := cachefiles.o

46
fs/cachefiles/error_inject.c Normal file
View file

@ -0,0 +1,46 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/* Error injection handling.
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/sysctl.h>
#include "internal.h"
unsigned int cachefiles_error_injection_state;
static struct ctl_table_header *cachefiles_sysctl;
static struct ctl_table cachefiles_sysctls[] = {
{
.procname = "error_injection",
.data = &cachefiles_error_injection_state,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_douintvec,
},
{}
};
static struct ctl_table cachefiles_sysctls_root[] = {
{
.procname = "cachefiles",
.mode = 0555,
.child = cachefiles_sysctls,
},
{}
};
int __init cachefiles_register_error_injection(void)
{
cachefiles_sysctl = register_sysctl_table(cachefiles_sysctls_root);
if (!cachefiles_sysctl)
return -ENOMEM;
return 0;
}
void cachefiles_unregister_error_injection(void)
{
unregister_sysctl_table(cachefiles_sysctl);
}

42
fs/cachefiles/internal.h
View file

@ -64,7 +64,47 @@ struct cachefiles_cache {
/*
* Debug tracing.
* error_inject.c
*/
#ifdef CONFIG_CACHEFILES_ERROR_INJECTION
extern unsigned int cachefiles_error_injection_state;
extern int cachefiles_register_error_injection(void);
extern void cachefiles_unregister_error_injection(void);
#else
#define cachefiles_error_injection_state 0
static inline int cachefiles_register_error_injection(void)
{
return 0;
}
static inline void cachefiles_unregister_error_injection(void)
{
}
#endif
static inline int cachefiles_inject_read_error(void)
{
return cachefiles_error_injection_state & 2 ? -EIO : 0;
}
static inline int cachefiles_inject_write_error(void)
{
return cachefiles_error_injection_state & 2 ? -EIO :
cachefiles_error_injection_state & 1 ? -ENOSPC :
0;
}
static inline int cachefiles_inject_remove_error(void)
{
return cachefiles_error_injection_state & 2 ? -EIO : 0;
}
/*
* Debug tracing
*/
extern unsigned cachefiles_debug;
#define CACHEFILES_DEBUG_KENTER 1

12
fs/cachefiles/main.c
View file

@ -36,8 +36,18 @@ MODULE_LICENSE("GPL");
*/
static int __init cachefiles_init(void)
{
int ret;
ret = cachefiles_register_error_injection();
if (ret < 0)
goto error_einj;
pr_info("Loaded\n");
return 0;
error_einj:
pr_err("failed to register: %d\n", ret);
return ret;
}
fs_initcall(cachefiles_init);
@ -48,6 +58,8 @@ fs_initcall(cachefiles_init);
static void __exit cachefiles_exit(void)
{
pr_info("Unloading\n");
cachefiles_unregister_error_injection();
}
module_exit(cachefiles_exit);