Commit a70f6526 authored by David Howells's avatar David Howells
Browse files

cachefiles: Add some error injection support 



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: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff 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
parent 8390fbc4

fs/cachefiles/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -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.

fs/cachefiles/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -6,4 +6,6 @@ 
cachefiles-y := \

	main.o



cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o



obj-$(CONFIG_CACHEFILES) := cachefiles.o

fs/cachefiles/error_inject.c

0 → 100644
+46 −0
Original line number Diff line number Diff line 
// 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);

}

fs/cachefiles/internal.h

+41 −1
Original line number Diff line number Diff line
@@ -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

fs/cachefiles/main.c

+12 −0
Original line number Diff line number Diff line
@@ -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);