File 0002-systemd-Add-a-generator-to-mount-sysroot-via-NFSv4-i.patch of Package nfs-utils
From 6cb1a43a10841aded94efcdb2ab4f2c2ed8450f2 Mon Sep 17 00:00:00 2001
Message-ID: <6cb1a43a10841aded94efcdb2ab4f2c2ed8450f2.1747753109.git.antonio.feijoo@suse.com>
In-Reply-To: <cover.1747753109.git.antonio.feijoo@suse.com>
References: <cover.1747753109.git.antonio.feijoo@suse.com>
From: Antonio Alvarez Feijoo <antonio.feijoo@suse.com>
Date: Tue, 20 May 2025 16:47:00 +0200
Subject: [PATCH 2/2] systemd: Add a generator to mount /sysroot via NFSv4 in
the initrd
This patch adds the nfsroot-generator to parse the following kernel
command line options in the initrd:
- root=/dev/nfs nfsroot=[<server>:]<path>[,<options>]
Defined in <kernel_source>/Documentation/admin-guide/nfs/nfsroot.rst
- root=nfs[4]:[<server>:]<path>[:<options>]
Defined in dracut.cmdline(7).
Since systemd does not create the sysroot.mount unit when nfsroot is
requested [1], this generator can create it so the real root will be
mounted in /sysroot, and also add the dependency to
initrd-root-fs.target to automatically continue the boot process.
[1] https://github.com/systemd/systemd/commit/77b8e92de8264c0b656a7d2fb437dd8d598ab597
Signed-off-by: Antonio Alvarez Feijoo <antonio.feijoo@suse.com>
---
.gitignore | 1 +
systemd/Makefile.am | 8 +-
systemd/nfs.systemd.man | 62 +++++++--
systemd/nfsroot-generator.c | 243 ++++++++++++++++++++++++++++++++++++
systemd/systemd.c | 16 ++-
systemd/systemd.h | 1 +
6 files changed, 320 insertions(+), 11 deletions(-)
create mode 100644 systemd/nfsroot-generator.c
diff --git a/.gitignore b/.gitignore
index 08ce7cdf..622134bb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -80,6 +80,7 @@ tests/nsm_client/nlm_sm_inter_svc.c
tests/nsm_client/nlm_sm_inter_xdr.c
utils/nfsidmap/nfsidmap
utils/nfsref/nfsref
+systemd/nfsroot-generator
systemd/nfs-server-generator
systemd/rpc-pipefs-generator
systemd/nfs-config.service
diff --git a/systemd/Makefile.am b/systemd/Makefile.am
index b4483222..5e481421 100644
--- a/systemd/Makefile.am
+++ b/systemd/Makefile.am
@@ -59,15 +59,19 @@ EXTRA_DIST = $(unit_files) $(udev_files) $(man5_MANS) $(man7_MANS)
generator_dir = $(unitdir)/../system-generators
-EXTRA_PROGRAMS = nfs-server-generator rpc-pipefs-generator
+EXTRA_PROGRAMS = nfsroot-generator nfs-server-generator rpc-pipefs-generator
genexecdir = $(generator_dir)
COMMON_SRCS = systemd.c systemd.h
+nfsroot_generator_SOURCES = $(COMMON_SRCS) nfsroot-generator.c
+
nfs_server_generator_SOURCES = $(COMMON_SRCS) nfs-server-generator.c
rpc_pipefs_generator_SOURCES = $(COMMON_SRCS) rpc-pipefs-generator.c
+nfsroot_generator_LDADD = ../support/nfs/libnfs.la
+
nfs_server_generator_LDADD = ../support/export/libexport.a \
../support/nfs/libnfs.la \
../support/misc/libmisc.a \
@@ -78,7 +82,7 @@ nfs_server_generator_LDADD = ../support/export/libexport.a \
rpc_pipefs_generator_LDADD = ../support/nfs/libnfs.la
if INSTALL_SYSTEMD
-genexec_PROGRAMS = nfs-server-generator rpc-pipefs-generator
+genexec_PROGRAMS = nfsroot-generator nfs-server-generator rpc-pipefs-generator
install-data-hook: $(unit_files) $(udev_files)
mkdir -p $(DESTDIR)/$(unitdir)
cp $(unit_files) $(DESTDIR)/$(unitdir)
diff --git a/systemd/nfs.systemd.man b/systemd/nfs.systemd.man
index f49e7776..a8476038 100644
--- a/systemd/nfs.systemd.man
+++ b/systemd/nfs.systemd.man
@@ -14,13 +14,13 @@ The
.I nfs-utils
package provides a suite of
.I systemd
-unit files which allow the various services to be started and
-managed. These unit files ensure that the services are started in the
-correct order, and the prerequisites are active before dependant
-services start. As there are quite few unit files, it is not
-immediately obvious how best to achieve certain results. The
-following subsections attempt to cover the issues that are most likely
-to come up.
+unit files and generators which allow the various services to be
+started and managed. These unit files and generators ensure that the
+services are started in the correct order, and the prerequisites are
+active before dependant services start. As there are quite a few unit
+files and generators, it is not immediately obvious how best to achieve
+certain results. The following subsections attempt to cover the issues
+that are most likely to come up.
.SS Configuration
The standard systemd unit files do not provide any easy way to pass
any command line arguments to daemons so as to configure their
@@ -166,6 +166,52 @@ file is present. If a site needs this file present but does not want
running, it can be masked with
.RS
.B systemctl mask rpc-gssd
+.SS Generators
+systemd unit generators are small executables placed in
+.I /usr/lib/systemd/system-generators/
+to dynamically extend the unit file hierarchy. The
+.I nfs-utils
+package provides three:
+.TP
+.B nfsroot-generator
+It creates the
+.B sysroot.mount
+unit to mount /sysroot via NFSv4 in the initrd, if it detects one the
+following options in the kernel command line:
+.PP
+.RS
+.B root=/dev/nfs nfsroot=[<server>:]<path>[,<options>]
+.PP
+.RS
+Defined in
+.I <kernel_source>/Documentation/admin-guide/nfs/nfsroot.rst
+.RE
+.RE
+.PP
+.RS
+.B root=nfs[4]:[<server>:]<path>[:<options>]
+.PP
+.RS
+Defined in
+.BR dracut.cmdline (7).
+.PP
+.B NOTE:
+Although "nfs" can be used as type indicator for the mountpoint, the
+mount unit will use always "nfs4".
+.RE
+.RE
+.TP
+.B nfs-server-generator
+It creates ordering dependencies between
+.I nfs-server.service
+and various filesystem mounts: it should start before any "nfs"
+mountpoints are mounted, in case they are loop-back mounts, and after
+all exported filesystems are mounted, so there is no risk of exporting
+the underlying directory.
+.TP
+.B rpc-pipefs-generator
+It creates ordering dependencies between NFS services and the
+rpc_pipefs mountpoint.
.RE
.SH FILES
/etc/nfs.conf
@@ -180,6 +226,8 @@ and in related
.I conf.d
drop-in directories.
.SH SEE ALSO
+.BR bootup (7),
+.BR systemd.generator (7),
.BR systemd.unit (5),
.BR nfs.conf (5),
.BR nfsmount.conf (5).
diff --git a/systemd/nfsroot-generator.c b/systemd/nfsroot-generator.c
new file mode 100644
index 00000000..52bd0752
--- /dev/null
+++ b/systemd/nfsroot-generator.c
@@ -0,0 +1,243 @@
+/*
+ * nfsroot-generator:
+ * systemd generator to mount /sysroot via NFSv4 in the initrd
+ */
+
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "nfslib.h"
+#include "systemd.h"
+
+struct nfsroot_info {
+ char *server;
+ char *path;
+ char *options;
+};
+
+/* Valid kernel command line options:
+ *
+ * - root=/dev/nfs nfsroot=[<server>:]<path>[,<options>]
+ *
+ * Defined in <kernel_source>/Documentation/admin-guide/nfs/nfsroot.rst
+ *
+ * - root=nfs[4]:[<server>:]<path>[:<options>]
+ *
+ * Defined in dracut.cmdline(7).
+ *
+ * Allow to use both "nfs" or "nfs4" as type indicator,
+ * although the mount unit will use always "nfs4".
+ *
+ * If <server> is not set, it is determined by the 2nd
+ * token of the ip parameter:
+ *
+ * ip=<client-ip>:<server-ip>:...
+ *
+ * <options> can be appended with the prefix ":" or ","
+ * and are separated by ",".
+ */
+static int get_nfsroot_info_from_cmdline(struct nfsroot_info *info)
+{
+ FILE *f;
+ char buf[4096], *p;
+ char *root = NULL, *nfsroot = NULL, *ip = NULL;
+ char *colon, *slash, *comma;
+ size_t size;
+
+ f = fopen("/proc/cmdline", "r");
+ if (!f)
+ return errno;
+
+ if (fgets(buf, sizeof(buf), f) == NULL)
+ return EIO;
+
+ fclose(f);
+
+ size = strlen(buf);
+ if (buf[size - 1] == '\n')
+ buf[size - 1] = '\0';
+ for (p = strtok(buf, " "); p; p = strtok(NULL, " ")) {
+ if (!strncmp(p, "root=", strlen("root=")))
+ root = p + strlen("root=");
+ else if (!strncmp(p, "nfsroot=", strlen("nfsroot=")))
+ nfsroot = p + strlen("nfsroot=");
+ else if (!strncmp(p, "ip=", strlen("ip=")))
+ ip = p + strlen("ip=");
+ }
+
+ if (!strcmp(root, "/dev/nfs")) {
+ /* Require the nfsroot parameter with the pseudo-NFS-device */
+ if (!nfsroot)
+ return EINVAL;
+
+ } else if (root) {
+ /* Mount type: "nfs" or "nfs4" */
+ colon = strchr(root, ':');
+ if (colon == NULL)
+ return EINVAL;
+ if (strncmp(root, "nfs:", strlen("nfs:")) &&
+ strncmp(root, "nfs4:", strlen("nfs4:")))
+ return EINVAL;
+
+ nfsroot = colon + 1;
+ }
+
+ slash = strchr(nfsroot, '/');
+ if (slash == NULL)
+ return EINVAL;
+
+ if (slash - nfsroot > 0) {
+ if ((slash - 1)[0] != ':')
+ return EINVAL;
+
+ info->server = strndup(nfsroot, slash - nfsroot - 1);
+ nfsroot = slash;
+ } else {
+ /* Require the ip parameter if <server> is unset */
+ if (!ip)
+ return EINVAL;
+
+ colon = strchr(ip, ':');
+ if (colon == NULL)
+ return EINVAL;
+ ip = colon + 1;
+ colon = strchr(ip, ':');
+ if (colon == NULL)
+ return EINVAL;
+ info->server = strndup(ip, colon - ip);
+ }
+ if (!info->server)
+ return ENOMEM;
+
+ colon = strchr(nfsroot, ':');
+ if (colon != NULL) {
+ info->path = strndup(nfsroot, colon - nfsroot);
+ nfsroot = colon + 1;
+ } else {
+ comma = strchr(nfsroot, ',');
+ if (comma == NULL) {
+ info->path = strdup(nfsroot);
+ } else {
+ info->path = strndup(nfsroot, comma - nfsroot);
+ nfsroot = comma + 1;
+ }
+ }
+ if (!info->path)
+ return ENOMEM;
+
+ if ((colon || comma) && strlen(nfsroot) > 0) {
+ /* Skip checking <options> format */
+ info->options = strdup(nfsroot);
+ if (!info->options)
+ return ENOMEM;
+ }
+
+ return 0;
+}
+
+static int generate_sysroot_mount_unit(const struct nfsroot_info *info,
+ const char *dirname)
+{
+ int ret = 0;
+ char *path, *rpath;
+ char dirbase[] = "/initrd-root-fs.target.requires";
+ char filebase[] = "/sysroot.mount";
+ FILE *f;
+
+ path = malloc(strlen(dirname) + 1 + sizeof(filebase));
+ if (!path)
+ return ENOMEM;
+ sprintf(path, "%s", dirname);
+ mkdir(path, 0755);
+ strcat(path, filebase);
+ f = fopen(path, "w");
+ if (!f) {
+ ret = errno;
+ goto cleanup;
+ }
+
+ fprintf(f, "# Automatically generated by nfsroot-generator\n\n[Unit]\n");
+ fprintf(f, "Description=NFSv4 Root File System\n");
+ fprintf(f, "SourcePath=/proc/cmdline\n");
+ fprintf(f, "Requires=modprobe@sunrpc.service rpc_pipefs.target\n");
+ fprintf(f, "Wants=nfs-idmapd.service network-online.target remote-fs-pre.target\n");
+ fprintf(f, "After=modprobe@sunrpc.service nfs-idmapd.service network-online.target remote-fs-pre.target rpc_pipefs.target\n");
+ fprintf(f, "Before=initrd-root-fs.target remote-fs.target\n");
+ fprintf(f, "\n[Mount]\n");
+ fprintf(f, "What=%s:%s\n", info->server, info->path);
+ fprintf(f, "Where=/sysroot\n");
+ fprintf(f, "Type=nfs4\n");
+ if (info->options)
+ fprintf(f, "Options=%s\n", info->options);
+
+ fclose(f);
+
+ rpath = malloc(strlen(dirname) + 1 + sizeof(dirbase) + sizeof(filebase));
+ if (!rpath) {
+ ret = ENOMEM;
+ goto cleanup;
+ }
+ sprintf(rpath, "%s%s", dirname, dirbase);
+ mkdir(rpath, 0755);
+ strcat(rpath, filebase);
+
+ if (symlink(path, rpath) < 0 && errno != EEXIST)
+ ret = errno;
+
+ free(rpath);
+cleanup:
+ free(path);
+
+ return ret;
+}
+
+int main(int argc, char *argv[])
+{
+ int ret;
+ struct nfsroot_info info = {
+ .server = NULL,
+ .path = NULL,
+ .options = NULL,
+ };
+
+ /* Avoid using any external services */
+ xlog_syslog(0);
+
+ if (argc != 4 || argv[1][0] != '/') {
+ fprintf(stderr, "nfsroot-generator: mount /sysroot via NFSv4 in the initrd\n");
+ fprintf(stderr, "Usage: normal-dir early-dir late-dir\n");
+ exit(1);
+ }
+
+ if (!systemd_in_initrd())
+ exit(0);
+
+ ret = get_nfsroot_info_from_cmdline(&info);
+ if (ret) {
+ fprintf(stderr, "nfsroot-generator: failed to get nfsroot from kernel command line: %s\n",
+ strerror(ret));
+ goto cleanup;
+ }
+
+ if (info.server && info.path) {
+ ret = generate_sysroot_mount_unit(&info, argv[1]);
+ if (ret) {
+ fprintf(stderr, "nfsroot-generator: failed to generate sysroot.mount unit: %s\n",
+ strerror(ret));
+ }
+ }
+
+cleanup:
+ if (info.server)
+ free(info.server);
+ if (info.path)
+ free(info.path);
+ if (info.options)
+ free(info.options);
+
+ exit(ret);
+}
diff --git a/systemd/systemd.c b/systemd/systemd.c
index c7bdb4d2..fe749a99 100644
--- a/systemd/systemd.c
+++ b/systemd/systemd.c
@@ -1,13 +1,12 @@
/*
* Helper functions for systemd generators in nfs-utils.
- *
- * Currently just systemd_escape().
*/
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
+#include <unistd.h>
#include "systemd.h"
static const char hex[16] =
@@ -132,3 +131,16 @@ out:
sprintf(p, "%s", suffix);
return result;
}
+
+/*
+ * check if the system is running in the initrd, following the same logic as
+ * systemd, described in os-release(5):
+ *
+ * In the initrd[2] and exitrd, /etc/initrd-release plays the same role as
+ * os-release in the main system. Additionally, the presence of that file
+ * means that the system is in the initrd/exitrd phase.
+ */
+int systemd_in_initrd(void)
+{
+ return (access("/etc/initrd-release", F_OK) >= 0);
+}
diff --git a/systemd/systemd.h b/systemd/systemd.h
index 25235ec8..72a04c86 100644
--- a/systemd/systemd.h
+++ b/systemd/systemd.h
@@ -2,5 +2,6 @@
#define SYSTEMD_H
char *systemd_escape(char *path, char *suffix);
+int systemd_in_initrd(void);
#endif /* SYSTEMD_H */
--
2.43.0
