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@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
Link: https://lore.kernel.org/r/163819624706.215744.6911916249119962943.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1
---
fs/cachefiles/Kconfig | 7 ++++++
fs/cachefiles/Makefile | 2 ++
fs/cachefiles/error_inject.c | 46 ++++++++++++++++++++++++++++++++++++++++++
fs/cachefiles/internal.h | 42 +++++++++++++++++++++++++++++++++++++-
fs/cachefiles/main.c | 12 +++++++++++
5 files changed, 108 insertions(+), 1 deletion(-)
create mode 100644 fs/cachefiles/error_inject.c
diff --git a/fs/cachefiles/Kconfig b/fs/cachefiles/Kconfig
index 6827b40f7ddc..719faeeda168 100644
--- a/fs/cachefiles/Kconfig
+++ b/fs/cachefiles/Kconfig
@@ -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.
diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile
index a7f3e982e249..183fb5f3b8b1 100644
--- a/fs/cachefiles/Makefile
+++ b/fs/cachefiles/Makefile
@@ -6,4 +6,6 @@
cachefiles-y := \
main.o
+cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o
+
obj-$(CONFIG_CACHEFILES) := cachefiles.o
diff --git a/fs/cachefiles/error_inject.c b/fs/cachefiles/error_inject.c
new file mode 100644
index 000000000000..58f8aec964e4
--- /dev/null
+++ b/fs/cachefiles/error_inject.c
@@ -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@xxxxxxxxxx)
+ */
+
+#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);
+}
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index cff4b2a5f928..1f2fea902d3e 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -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
diff --git a/fs/cachefiles/main.c b/fs/cachefiles/main.c
index 47bc1cc078de..387d42c7185f 100644
--- a/fs/cachefiles/main.c
+++ b/fs/cachefiles/main.c
@@ -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);
--
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