NFSD: Added fault injection

Fault injection on the NFS server makes it easier to test the client's
state manager and recovery threads.  Simulating errors on the server is
easier than finding the right conditions that cause them naturally.

This patch uses debugfs to add a simple framework for fault injection to
the server.  This framework is a config option, and can be enabled
through CONFIG_NFSD_FAULT_INJECTION.  Assuming you have debugfs mounted
to /sys/debug, a set of files will be created in /sys/debug/nfsd/.
Writing to any of these files will cause the corresponding action and
write a log entry to dmesg.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/fs/nfsd/fault_inject.c b/fs/nfsd/fault_inject.c
new file mode 100644
index 0000000..ce7f075
--- /dev/null
+++ b/fs/nfsd/fault_inject.c
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2011 Bryan Schumaker <bjschuma@netapp.com>
+ *
+ * Uses debugfs to create fault injection points for client testing
+ */
+
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+
+#include "state.h"
+#include "fault_inject.h"
+
+struct nfsd_fault_inject_op {
+	char *file;
+	void (*func)(u64);
+};
+
+static struct nfsd_fault_inject_op inject_ops[] = {
+	{
+		.file   = "forget_clients",
+		.func   = nfsd_forget_clients,
+	},
+	{
+		.file   = "forget_locks",
+		.func   = nfsd_forget_locks,
+	},
+	{
+		.file   = "forget_openowners",
+		.func   = nfsd_forget_openowners,
+	},
+	{
+		.file   = "forget_delegations",
+		.func   = nfsd_forget_delegations,
+	},
+	{
+		.file   = "recall_delegations",
+		.func   = nfsd_recall_delegations,
+	},
+};
+
+static long int NUM_INJECT_OPS = sizeof(inject_ops) / sizeof(struct nfsd_fault_inject_op);
+static struct dentry *debug_dir;
+
+static int nfsd_inject_set(void *op_ptr, u64 val)
+{
+	struct nfsd_fault_inject_op *op = op_ptr;
+
+	if (val == 0)
+		printk(KERN_INFO "NFSD Fault Injection: %s (all)", op->file);
+	else
+		printk(KERN_INFO "NFSD Fault Injection: %s (n = %llu)", op->file, val);
+
+	op->func(val);
+	return 0;
+}
+
+static int nfsd_inject_get(void *data, u64 *val)
+{
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_nfsd, nfsd_inject_get, nfsd_inject_set, "%llu\n");
+
+void nfsd_fault_inject_cleanup(void)
+{
+	debugfs_remove_recursive(debug_dir);
+}
+
+int nfsd_fault_inject_init(void)
+{
+	unsigned int i;
+	struct nfsd_fault_inject_op *op;
+	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+
+	debug_dir = debugfs_create_dir("nfsd", NULL);
+	if (!debug_dir)
+		goto fail;
+
+	for (i = 0; i < NUM_INJECT_OPS; i++) {
+		op = &inject_ops[i];
+		if (!debugfs_create_file(op->file, mode, debug_dir, op, &fops_nfsd))
+			goto fail;
+	}
+	return 0;
+
+fail:
+	nfsd_fault_inject_cleanup();
+	return -ENOMEM;
+}