From:   Scott Mayhew <smayhew@redhat.com>
To:     steved@redhat.com
Cc:     jlayton@kernel.org, linux-nfs@vger.kernel.org
Subject: [nfs-utils PATCH v2 1/7] Revert "nfsdcltrack: remove the nfsdcld daemon"
Date:   Tue, 18 Dec 2018 09:30:12 -0500
Message-Id: <20181218143018.28575-2-smayhew@redhat.com>
In-Reply-To: <20181218143018.28575-1-smayhew@redhat.com>
References: <20181218143018.28575-1-smayhew@redhat.com>
Sender: linux-nfs-owner@vger.kernel.org
Precedence: bulk

This reverts commit 2cf11ec6ed261ef56bbd0d73ff404fe69f1fefb0.

nfsdcld was originally deprecated in favor of a usermodehelper, so as to
not require another running daemon.  But that turned out to make
namespaced nfsd's too difficult, so this commit brings back nfsdcld.

A few things have been changed since nfsdcld was removed in 2012:

- libnfs.a is now libnfs.la
- sqlite_insert_client and sqlite_check_client both take a bool
  has_session which is being hard-coded to false for now.
- sqlite_insert_client also takes a bool zerotime which is being
  hard-coded to false.
- an xlog() call whose arguments did not match the format string
  (and could crash nfsdcld) has been fixed
- cld_pipe_open() now calls event_initialized() rather than checking for
  EVLIST_INIT directly (which does not compile with newer versions
  of libevent).

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
 .gitignore                    |   1 +
 utils/nfsdcltrack/Makefile.am |   7 +-
 utils/nfsdcltrack/nfsdcld.c   | 611 ++++++++++++++++++++++++++++++++++
 utils/nfsdcltrack/nfsdcld.man | 185 ++++++++++
 4 files changed, 802 insertions(+), 2 deletions(-)
 create mode 100644 utils/nfsdcltrack/nfsdcld.c
 create mode 100644 utils/nfsdcltrack/nfsdcld.man

diff --git a/.gitignore b/.gitignore
index e91e7a2..d4f4f34 100644
--- a/.gitignore
+++ b/.gitignore
@@ -54,6 +54,7 @@ utils/rquotad/rquotad
 utils/rquotad/rquota.h
 utils/rquotad/rquota_xdr.c
 utils/showmount/showmount
+utils/nfsdcltrack/nfsdcld
 utils/nfsdcltrack/nfsdcltrack
 utils/statd/statd
 tools/locktest/testlk
diff --git a/utils/nfsdcltrack/Makefile.am b/utils/nfsdcltrack/Makefile.am
index 2f7fe3d..0f599c0 100644
--- a/utils/nfsdcltrack/Makefile.am
+++ b/utils/nfsdcltrack/Makefile.am
@@ -4,11 +4,14 @@
 # overridden at config time. The kernel "knows" the /sbin name.
 sbindir = /sbin
 
-man8_MANS	= nfsdcltrack.man
+man8_MANS	= nfsdcld.man nfsdcltrack.man
 EXTRA_DIST	= $(man8_MANS)
 
 AM_CFLAGS	+= -D_LARGEFILE64_SOURCE
-sbin_PROGRAMS	= nfsdcltrack
+sbin_PROGRAMS	= nfsdcld nfsdcltrack
+
+nfsdcld_SOURCES = nfsdcld.c sqlite.c
+nfsdcld_LDADD = ../../support/nfs/libnfs.la $(LIBEVENT) $(LIBSQLITE) $(LIBCAP)
 
 noinst_HEADERS	= sqlite.h
 
diff --git a/utils/nfsdcltrack/nfsdcld.c b/utils/nfsdcltrack/nfsdcld.c
new file mode 100644
index 0000000..082f3ab
--- /dev/null
+++ b/utils/nfsdcltrack/nfsdcld.c
@@ -0,0 +1,611 @@
+/*
+ * nfsdcld.c -- NFSv4 client name tracking daemon
+ *
+ * Copyright (C) 2011  Red Hat, Jeff Layton <jlayton@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif /* HAVE_CONFIG_H */
+
+#include <errno.h>
+#include <event.h>
+#include <stdbool.h>
+#include <getopt.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <libgen.h>
+#include <sys/inotify.h>
+#ifdef HAVE_SYS_CAPABILITY_H
+#include <sys/prctl.h>
+#include <sys/capability.h>
+#endif
+
+#include "xlog.h"
+#include "nfslib.h"
+#include "cld.h"
+#include "sqlite.h"
+
+#ifndef PIPEFS_DIR
+#define PIPEFS_DIR NFS_STATEDIR "/rpc_pipefs"
+#endif
+
+#define DEFAULT_CLD_PATH	PIPEFS_DIR "/nfsd/cld"
+
+#ifndef CLD_DEFAULT_STORAGEDIR
+#define CLD_DEFAULT_STORAGEDIR NFS_STATEDIR "/nfsdcld"
+#endif
+
+#define UPCALL_VERSION		1
+
+/* private data structures */
+struct cld_client {
+	int			cl_fd;
+	struct event		cl_event;
+	struct cld_msg	cl_msg;
+};
+
+/* global variables */
+static char *pipepath = DEFAULT_CLD_PATH;
+static int 		inotify_fd = -1;
+static struct event	pipedir_event;
+
+static struct option longopts[] =
+{
+	{ "help", 0, NULL, 'h' },
+	{ "foreground", 0, NULL, 'F' },
+	{ "debug", 0, NULL, 'd' },
+	{ "pipe", 1, NULL, 'p' },
+	{ "storagedir", 1, NULL, 's' },
+	{ NULL, 0, 0, 0 },
+};
+
+/* forward declarations */
+static void cldcb(int UNUSED(fd), short which, void *data);
+
+static void
+usage(char *progname)
+{
+	printf("%s [ -hFd ] [ -p pipe ] [ -s dir ]\n", progname);
+}
+
+static int
+cld_set_caps(void)
+{
+	int ret = 0;
+#ifdef HAVE_SYS_CAPABILITY_H
+	unsigned long i;
+	cap_t caps;
+
+	if (getuid() != 0) {
+		xlog(L_ERROR, "Not running as root. Daemon won't be able to "
+			      "open the pipe after dropping capabilities!");
+		return -EINVAL;
+	}
+
+	/* prune the bounding set to nothing */
+	for (i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0 ; ++i) {
+		ret = prctl(PR_CAPBSET_DROP, i, 0, 0, 0);
+		if (ret) {
+			xlog(L_ERROR, "Unable to prune capability %lu from "
+				      "bounding set: %m", i);
+			return -errno;
+		}
+	}
+
+	/* get a blank capset */
+	caps = cap_init();
+	if (caps == NULL) {
+		xlog(L_ERROR, "Unable to get blank capability set: %m");
+		return -errno;
+	}
+
+	/* reset the process capabilities */
+	if (cap_set_proc(caps) != 0) {
+		xlog(L_ERROR, "Unable to set process capabilities: %m");
+		ret = -errno;
+	}
+	cap_free(caps);
+#endif
+	return ret;
+}
+
+#define INOTIFY_EVENT_MAX (sizeof(struct inotify_event) + NAME_MAX)
+
+static int
+cld_pipe_open(struct cld_client *clnt)
+{
+	int fd;
+
+	xlog(D_GENERAL, "%s: opening upcall pipe %s", __func__, pipepath);
+	fd = open(pipepath, O_RDWR, 0);
+	if (fd < 0) {
+		xlog(D_GENERAL, "%s: open of %s failed: %m", __func__, pipepath);
+		return -errno;
+	}
+
+	if (event_initialized(&clnt->cl_event))
+		event_del(&clnt->cl_event);
+	if (clnt->cl_fd >= 0)
+		close(clnt->cl_fd);
+
+	clnt->cl_fd = fd;
+	event_set(&clnt->cl_event, clnt->cl_fd, EV_READ, cldcb, clnt);
+	/* event_add is done by the caller */
+	return 0;
+}
+
+static void
+cld_inotify_cb(int UNUSED(fd), short which, void *data)
+{
+	int ret;
+	size_t elen;
+	ssize_t rret;
+	char evbuf[INOTIFY_EVENT_MAX];
+	char *dirc = NULL, *pname;
+	struct inotify_event *event = (struct inotify_event *)evbuf;
+	struct cld_client *clnt = data;
+
+	if (which != EV_READ)
+		return;
+
+	xlog(D_GENERAL, "%s: called for EV_READ", __func__);
+
+	dirc = strndup(pipepath, PATH_MAX);
+	if (!dirc) {
+		xlog(L_ERROR, "%s: unable to allocate memory", __func__);
+		goto out;
+	}
+
+	rret = read(inotify_fd, evbuf, INOTIFY_EVENT_MAX);
+	if (rret < 0) {
+		xlog(L_ERROR, "%s: read from inotify fd failed: %m", __func__);
+		goto out;
+	}
+
+	/* check to see if we have a filename in the evbuf */
+	if (!event->len) {
+		xlog(D_GENERAL, "%s: no filename in inotify event", __func__);
+		goto out;
+	}
+
+	pname = basename(dirc);
+	elen = strnlen(event->name, event->len);
+
+	/* does the filename match our pipe? */
+	if (strlen(pname) != elen || memcmp(pname, event->name, elen)) {
+		xlog(D_GENERAL, "%s: wrong filename (%s)", __func__,
+				event->name);
+		goto out;
+	}
+
+	ret = cld_pipe_open(clnt);
+	switch (ret) {
+	case 0:
+		/* readd the event for the cl_event pipe */
+		event_add(&clnt->cl_event, NULL);
+		break;
+	case -ENOENT:
+		/* pipe must have disappeared, wait for it to come back */
+		goto out;
+	default:
+		/* anything else is fatal */
+		xlog(L_FATAL, "%s: unable to open new pipe (%d). Aborting.",
+			ret, __func__);
+		exit(ret);
+	}
+
+out:
+	event_add(&pipedir_event, NULL);
+	free(dirc);
+}
+
+static int
+cld_inotify_setup(void)
+{
+	int ret;
+	char *dirc, *dname;
+
+	dirc = strndup(pipepath, PATH_MAX);
+	if (!dirc) {
+		xlog_err("%s: unable to allocate memory", __func__);
+		ret = -ENOMEM;
+		goto out_free;
+	}
+
+	dname = dirname(dirc);
+
+	inotify_fd = inotify_init();
+	if (inotify_fd < 0) {
+		xlog_err("%s: inotify_init failed: %m", __func__);
+		ret = -errno;
+		goto out_free;
+	}
+
+	ret = inotify_add_watch(inotify_fd, dname, IN_CREATE);
+	if (ret < 0) {
+		xlog_err("%s: inotify_add_watch failed: %m", __func__);
+		ret = -errno;
+		goto out_err;
+	}
+
+out_free:
+	free(dirc);
+	return 0;
+out_err:
+	close(inotify_fd);
+	goto out_free;
+}
+
+/*
+ * Set an inotify watch on the directory that should contain the pipe, and then
+ * try to open it. If it fails with anything but -ENOENT, return the error
+ * immediately.
+ *
+ * If it succeeds, then set up the pipe event handler. At that point, set up
+ * the inotify event handler and go ahead and return success.
+ */
+static int
+cld_pipe_init(struct cld_client *clnt)
+{
+	int ret;
+
+	xlog(D_GENERAL, "%s: init pipe handlers", __func__);
+
+	ret = cld_inotify_setup();
+	if (ret != 0)
+		goto out;
+
+	clnt->cl_fd = -1;
+	ret = cld_pipe_open(clnt);
+	switch (ret) {
+	case 0:
+		/* add the event and we're good to go */
+		event_add(&clnt->cl_event, NULL);
+		break;
+	case -ENOENT:
+		/* ignore this error -- cld_inotify_cb will handle it */
+		ret = 0;
+		break;
+	default:
+		/* anything else is fatal */
+		close(inotify_fd);
+		goto out;
+	}
+
+	/* set event for inotify read */
+	event_set(&pipedir_event, inotify_fd, EV_READ, cld_inotify_cb, clnt);
+	event_add(&pipedir_event, NULL);
+out:
+	return ret;
+}
+
+static void
+cld_not_implemented(struct cld_client *clnt)
+{
+	int ret;
+	ssize_t bsize, wsize;
+	struct cld_msg *cmsg = &clnt->cl_msg;
+
+	xlog(D_GENERAL, "%s: downcalling with not implemented error", __func__);
+
+	/* set up reply */
+	cmsg->cm_status = -EOPNOTSUPP;
+
+	bsize = sizeof(*cmsg);
+
+	wsize = atomicio((void *)write, clnt->cl_fd, cmsg, bsize);
+	if (wsize != bsize)
+		xlog(L_ERROR, "%s: problem writing to cld pipe (%ld): %m",
+			 __func__, wsize);
+
+	/* reopen pipe, just to be sure */
+	ret = cld_pipe_open(clnt);
+	if (ret) {
+		xlog(L_FATAL, "%s: unable to reopen pipe: %d", __func__, ret);
+		exit(ret);
+	}
+}
+
+static void
+cld_create(struct cld_client *clnt)
+{
+	int ret;
+	ssize_t bsize, wsize;
+	struct cld_msg *cmsg = &clnt->cl_msg;
+
+	xlog(D_GENERAL, "%s: create client record.", __func__);
+
+
+	ret = sqlite_insert_client(cmsg->cm_u.cm_name.cn_id,
+				   cmsg->cm_u.cm_name.cn_len,
+				   false,
+				   false);
+
+	cmsg->cm_status = ret ? -EREMOTEIO : ret;
+
+	bsize = sizeof(*cmsg);
+
+	xlog(D_GENERAL, "Doing downcall with status %d", cmsg->cm_status);
+	wsize = atomicio((void *)write, clnt->cl_fd, cmsg, bsize);
+	if (wsize != bsize) {
+		xlog(L_ERROR, "%s: problem writing to cld pipe (%ld): %m",
+			 __func__, wsize);
+		ret = cld_pipe_open(clnt);
+		if (ret) {
+			xlog(L_FATAL, "%s: unable to reopen pipe: %d",
+					__func__, ret);
+			exit(ret);
+		}
+	}
+}
+
+static void
+cld_remove(struct cld_client *clnt)
+{
+	int ret;
+	ssize_t bsize, wsize;
+	struct cld_msg *cmsg = &clnt->cl_msg;
+
+	xlog(D_GENERAL, "%s: remove client record.", __func__);
+
+	ret = sqlite_remove_client(cmsg->cm_u.cm_name.cn_id,
+				   cmsg->cm_u.cm_name.cn_len);
+
+	cmsg->cm_status = ret ? -EREMOTEIO : ret;
+
+	bsize = sizeof(*cmsg);
+
+	xlog(D_GENERAL, "%s: downcall with status %d", __func__,
+			cmsg->cm_status);
+	wsize = atomicio((void *)write, clnt->cl_fd, cmsg, bsize);
+	if (wsize != bsize) {
+		xlog(L_ERROR, "%s: problem writing to cld pipe (%ld): %m",
+			 __func__, wsize);
+		ret = cld_pipe_open(clnt);
+		if (ret) {
+			xlog(L_FATAL, "%s: unable to reopen pipe: %d",
+					__func__, ret);
+			exit(ret);
+		}
+	}
+}
+
+static void
+cld_check(struct cld_client *clnt)
+{
+	int ret;
+	ssize_t bsize, wsize;
+	struct cld_msg *cmsg = &clnt->cl_msg;
+
+	xlog(D_GENERAL, "%s: check client record", __func__);
+
+	ret = sqlite_check_client(cmsg->cm_u.cm_name.cn_id,
+				  cmsg->cm_u.cm_name.cn_len,
+				  false);
+
+	/* set up reply */
+	cmsg->cm_status = ret ? -EACCES : ret;
+
+	bsize = sizeof(*cmsg);
+
+	xlog(D_GENERAL, "%s: downcall with status %d", __func__,
+			cmsg->cm_status);
+	wsize = atomicio((void *)write, clnt->cl_fd, cmsg, bsize);
+	if (wsize != bsize) {
+		xlog(L_ERROR, "%s: problem writing to cld pipe (%ld): %m",
+			 __func__, wsize);
+		ret = cld_pipe_open(clnt);
+		if (ret) {
+			xlog(L_FATAL, "%s: unable to reopen pipe: %d",
+					__func__, ret);
+			exit(ret);
+		}
+	}
+}
+
+static void
+cld_gracedone(struct cld_client *clnt)
+{
+	int ret;
+	ssize_t bsize, wsize;
+	struct cld_msg *cmsg = &clnt->cl_msg;
+
+	xlog(D_GENERAL, "%s: grace done. cm_gracetime=%ld", __func__,
+			cmsg->cm_u.cm_gracetime);
+
+	ret = sqlite_remove_unreclaimed(cmsg->cm_u.cm_gracetime);
+
+	/* set up reply: downcall with 0 status */
+	cmsg->cm_status = ret ? -EREMOTEIO : ret;
+
+	bsize = sizeof(*cmsg);
+
+	xlog(D_GENERAL, "Doing downcall with status %d", cmsg->cm_status);
+	wsize = atomicio((void *)write, clnt->cl_fd, cmsg, bsize);
+	if (wsize != bsize) {
+		xlog(L_ERROR, "%s: problem writing to cld pipe (%ld): %m",
+			 __func__, wsize);
+		ret = cld_pipe_open(clnt);
+		if (ret) {
+			xlog(L_FATAL, "%s: unable to reopen pipe: %d",
+					__func__, ret);
+			exit(ret);
+		}
+	}
+}
+
+static void
+cldcb(int UNUSED(fd), short which, void *data)
+{
+	ssize_t len;
+	struct cld_client *clnt = data;
+	struct cld_msg *cmsg = &clnt->cl_msg;
+
+	if (which != EV_READ)
+		goto out;
+
+	len = atomicio(read, clnt->cl_fd, cmsg, sizeof(*cmsg));
+	if (len <= 0) {
+		xlog(L_ERROR, "%s: pipe read failed: %m", __func__);
+		cld_pipe_open(clnt);
+		goto out;
+	}
+
+	if (cmsg->cm_vers > UPCALL_VERSION) {
+		xlog(L_ERROR, "%s: unsupported upcall version: %hu",
+				__func__, cmsg->cm_vers);
+		cld_pipe_open(clnt);
+		goto out;
+	}
+
+	switch(cmsg->cm_cmd) {
+	case Cld_Create:
+		cld_create(clnt);
+		break;
+	case Cld_Remove:
+		cld_remove(clnt);
+		break;
+	case Cld_Check:
+		cld_check(clnt);
+		break;
+	case Cld_GraceDone:
+		cld_gracedone(clnt);
+		break;
+	default:
+		xlog(L_WARNING, "%s: command %u is not yet implemented",
+				__func__, cmsg->cm_cmd);
+		cld_not_implemented(clnt);
+	}
+out:
+	event_add(&clnt->cl_event, NULL);
+}
+
+int
+main(int argc, char **argv)
+{
+	char arg;
+	int rc = 0;
+	bool foreground = false;
+	char *progname;
+	char *storagedir = CLD_DEFAULT_STORAGEDIR;
+	struct cld_client clnt;
+
+	memset(&clnt, 0, sizeof(clnt));
+
+	progname = strdup(basename(argv[0]));
+	if (!progname) {
+		fprintf(stderr, "%s: unable to allocate memory.\n", argv[0]);
+		return 1;
+	}
+
+	event_init();
+	xlog_syslog(0);
+	xlog_stderr(1);
+
+	/* process command-line options */
+	while ((arg = getopt_long(argc, argv, "hdFp:s:", longopts,
+				  NULL)) != EOF) {
+		switch (arg) {
+		case 'd':
+			xlog_config(D_ALL, 1);
+			break;
+		case 'F':
+			foreground = true;
+			break;
+		case 'p':
+			pipepath = optarg;
+			break;
+		case 's':
+			storagedir = optarg;
+			break;
+		default:
+			usage(progname);
+			return 0;
+		}
+	}
+
+
+	xlog_open(progname);
+	if (!foreground) {
+		xlog_syslog(1);
+		xlog_stderr(0);
+		rc = daemon(0, 0);
+		if (rc) {
+			xlog(L_ERROR, "Unable to daemonize: %m");
+			goto out;
+		}
+	}
+
+	/* drop all capabilities */
+	rc = cld_set_caps();
+	if (rc)
+		goto out;
+
+	/*
+	 * now see if the storagedir is writable by root w/o CAP_DAC_OVERRIDE.
+	 * If it isn't then give the user a warning but proceed as if
+	 * everything is OK. If the DB has already been created, then
+	 * everything might still work. If it doesn't exist at all, then
+	 * assume that the maindb init will be able to create it. Fail on
+	 * anything else.
+	 */
+	if (access(storagedir, W_OK) == -1) {
+		switch (errno) {
+		case EACCES:
+			xlog(L_WARNING, "Storage directory %s is not writable. "
+					"Should be owned by root and writable "
+					"by owner!", storagedir);
+			break;
+		case ENOENT:
+			/* ignore and assume that we can create dir as root */
+			break;
+		default:
+			xlog(L_ERROR, "Unexpected error when checking access "
+				      "on %s: %m", storagedir);
+			rc = -errno;
+			goto out;
+		}
+	}
+
+	/* set up storage db */
+	rc = sqlite_prepare_dbh(storagedir);
+	if (rc) {
+		xlog(L_ERROR, "Failed to open main database: %d", rc);
+		goto out;
+	}
+
+	/* set up event handler */
+	rc = cld_pipe_init(&clnt);
+	if (rc)
+		goto out;
+
+	xlog(D_GENERAL, "%s: Starting event dispatch handler.", __func__);
+	rc = event_dispatch();
+	if (rc < 0)
+		xlog(L_ERROR, "%s: event_dispatch failed: %m", __func__);
+
+	close(clnt.cl_fd);
+	close(inotify_fd);
+out:
+	free(progname);
+	return rc;
+}
diff --git a/utils/nfsdcltrack/nfsdcld.man b/utils/nfsdcltrack/nfsdcld.man
new file mode 100644
index 0000000..9ddaf64
--- /dev/null
+++ b/utils/nfsdcltrack/nfsdcld.man
@@ -0,0 +1,185 @@
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+.\" ========================================================================
+.\"
+.IX Title "NFSDCLD 8"
+.TH NFSDCLD 8 "2011-12-21" "" ""
+.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
+.\" way too many mistakes in technical documents.
+.if n .ad l
+.nh
+.SH "NAME"
+nfsdcld \- NFSv4 Client Tracking Daemon
+.SH "SYNOPSIS"
+.IX Header "SYNOPSIS"
+nfsdcld [\-d] [\-F] [\-p path] [\-s stable storage dir]
+.SH "DESCRIPTION"
+.IX Header "DESCRIPTION"
+nfsdcld is the NFSv4 client tracking daemon. It is not necessary to run
+this daemon on machines that are not acting as NFSv4 servers.
+.PP
+When a network partition is combined with a server reboot, there are
+edge conditions that can cause the server to grant lock reclaims when
+other clients have taken conflicting locks in the interim. A more detailed
+explanation of this issue is described in \s-1RFC\s0 3530, section 8.6.3.
+.PP
+In order to prevent these problems, the server must track a small amount
+of per-client information on stable storage. This daemon provides the
+userspace piece of that functionality.
+.SH "OPTIONS"
+.IX Header "OPTIONS"
+.IP "\fB\-d\fR, \fB\-\-debug\fR" 4
+.IX Item "-d, --debug"
+Enable debug level logging.
+.IP "\fB\-F\fR, \fB\-\-foreground\fR" 4
+.IX Item "-F, --foreground"
+Runs the daemon in the foreground and prints all output to stderr
+.IP "\fB\-p\fR \fIpipe\fR, \fB\-\-pipe\fR=\fIpipe\fR" 4
+.IX Item "-p pipe, --pipe=pipe"
+Location of the \*(L"cld\*(R" upcall pipe. The default value is
+\&\fI/var/lib/nfs/rpc_pipefs/nfsd/cld\fR. If the pipe does not exist when the
+daemon starts then it will wait for it to be created.
+.IP "\fB\-s\fR \fIstorage_dir\fR, \fB\-\-storagedir\fR=\fIstorage_dir\fR" 4
+.IX Item "-s storagedir, --storagedir=storage_dir"
+Directory where stable storage information should be kept. The default
+value is \fI/var/lib/nfs/nfsdcld\fR.
+.SH "NOTES"
+.IX Header "NOTES"
+The Linux kernel NFSv4 server has historically tracked this information
+on stable storage by manipulating information on the filesystem
+directly, in the directory to which \fI/proc/fs/nfsd/nfsv4recoverydir\fR
+points.
+.PP
+This daemon requires a kernel that supports the nfsdcld upcall. If the
+kernel does not support the new upcall, or is using the legacy client
+name tracking code then it will not create the pipe that nfsdcld uses to
+talk to the kernel.
+.PP
+This daemon should be run as root, as the pipe that it uses to communicate
+with the kernel is only accessable by root. The daemon however does drop all
+superuser capabilities after starting. Because of this, the \fIstoragedir\fR
+should be owned by root, and be readable and writable by owner.
+.SH "AUTHORS"
+.IX Header "AUTHORS"
+The nfsdcld daemon was developed by Jeff Layton <jlayton@redhat.com>.
-- 
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