nfsd: add a usermodehelper upcall for NFSv4 client ID tracking
Add a new client tracker upcall type that uses call_usermodehelper to
call out to a program. This seems to be the preferred method of
calling out to usermode these days for seldom-called upcalls. It's
simple and doesn't require a running daemon, so it should "just work"
as long as the binary is installed.
The client tracking exit operation is also changed to check for a
NULL pointer before running. The UMH upcall doesn't need to do anything
at module teardown time.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 151921b..2fc2f6c 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -927,6 +927,137 @@
.grace_done = nfsd4_cld_grace_done,
};
+/* upcall via usermodehelper */
+static char cltrack_prog[PATH_MAX] = "/sbin/nfsdcltrack";
+module_param_string(cltrack_prog, cltrack_prog, sizeof(cltrack_prog),
+ S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(cltrack_prog, "Path to the nfsdcltrack upcall program");
+
+static int
+nfsd4_umh_cltrack_upcall(char *cmd, char *arg)
+{
+ char *envp[] = { NULL };
+ char *argv[4];
+ int ret;
+
+ if (unlikely(!cltrack_prog[0])) {
+ dprintk("%s: cltrack_prog is disabled\n", __func__);
+ return -EACCES;
+ }
+
+ dprintk("%s: cmd: %s\n", __func__, cmd);
+ dprintk("%s: arg: %s\n", __func__, arg ? arg : "(null)");
+
+ argv[0] = (char *)cltrack_prog;
+ argv[1] = cmd;
+ argv[2] = arg;
+ argv[3] = NULL;
+
+ ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
+ /*
+ * Disable the upcall mechanism if we're getting an ENOENT or EACCES
+ * error. The admin can re-enable it on the fly by using sysfs
+ * once the problem has been fixed.
+ */
+ if (ret == -ENOENT || ret == -EACCES) {
+ dprintk("NFSD: %s was not found or isn't executable (%d). "
+ "Setting cltrack_prog to blank string!",
+ cltrack_prog, ret);
+ cltrack_prog[0] = '\0';
+ }
+ dprintk("%s: %s return value: %d\n", __func__, cltrack_prog, ret);
+
+ return ret;
+}
+
+static char *
+bin_to_hex_dup(const unsigned char *src, int srclen)
+{
+ int i;
+ char *buf, *hex;
+
+ /* +1 for terminating NULL */
+ buf = kmalloc((srclen * 2) + 1, GFP_KERNEL);
+ if (!buf)
+ return buf;
+
+ hex = buf;
+ for (i = 0; i < srclen; i++) {
+ sprintf(hex, "%2.2x", *src++);
+ hex += 2;
+ }
+ return buf;
+}
+
+static int
+nfsd4_umh_cltrack_init(struct net __attribute__((unused)) *net)
+{
+ return nfsd4_umh_cltrack_upcall("init", NULL);
+}
+
+static void
+nfsd4_umh_cltrack_create(struct nfs4_client *clp)
+{
+ char *hexid;
+
+ hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
+ if (!hexid) {
+ dprintk("%s: can't allocate memory for upcall!\n", __func__);
+ return;
+ }
+ nfsd4_umh_cltrack_upcall("create", hexid);
+ kfree(hexid);
+}
+
+static void
+nfsd4_umh_cltrack_remove(struct nfs4_client *clp)
+{
+ char *hexid;
+
+ hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
+ if (!hexid) {
+ dprintk("%s: can't allocate memory for upcall!\n", __func__);
+ return;
+ }
+ nfsd4_umh_cltrack_upcall("remove", hexid);
+ kfree(hexid);
+}
+
+static int
+nfsd4_umh_cltrack_check(struct nfs4_client *clp)
+{
+ int ret;
+ char *hexid;
+
+ hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
+ if (!hexid) {
+ dprintk("%s: can't allocate memory for upcall!\n", __func__);
+ return -ENOMEM;
+ }
+ ret = nfsd4_umh_cltrack_upcall("check", hexid);
+ kfree(hexid);
+ return ret;
+}
+
+static void
+nfsd4_umh_cltrack_grace_done(struct net __attribute__((unused)) *net,
+ time_t boot_time)
+{
+ char timestr[22]; /* FIXME: better way to determine max size? */
+
+ sprintf(timestr, "%ld", boot_time);
+ nfsd4_umh_cltrack_upcall("gracedone", timestr);
+}
+
+static struct nfsd4_client_tracking_ops nfsd4_umh_tracking_ops = {
+ .init = nfsd4_umh_cltrack_init,
+ .exit = NULL,
+ .create = nfsd4_umh_cltrack_create,
+ .remove = nfsd4_umh_cltrack_remove,
+ .check = nfsd4_umh_cltrack_check,
+ .grace_done = nfsd4_umh_cltrack_grace_done,
+};
+
int
nfsd4_client_tracking_init(struct net *net)
{
@@ -957,7 +1088,8 @@
nfsd4_client_tracking_exit(struct net *net)
{
if (client_tracking_ops) {
- client_tracking_ops->exit(net);
+ if (client_tracking_ops->exit)
+ client_tracking_ops->exit(net);
client_tracking_ops = NULL;
}
}