[systemd-devel] [PATCH] fstab-generator: introduce rd.weak_sysroot to bypass failures in sysroot.mount

[WANG Chao]

If specified kernel command line rd.weak_sysroot, fstab-generate will
generate a weaker version of sysroot.mount:
 - It's not required by initrd-root-fs.target.
 - It's not before initrd-root-fs.target.

So that failure in the weaker sysroot.mount will not fail
initrd-root-fs.target. And systemd will try continue rather than
entering isolated emergency mode.

Signed-off-by: WANG Chao <chaowang at redhat.com>
---
 man/kernel-command-line.xml           | 10 ++++++++++
 man/systemd-fstab-generator.xml       | 10 ++++++++++
 src/fstab-generator/fstab-generator.c |  5 ++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/man/kernel-command-line.xml b/man/kernel-command-line.xml
index a4b7d13..0c2e97d 100644
--- a/man/kernel-command-line.xml
+++ b/man/kernel-command-line.xml
@@ -274,6 +274,16 @@
                         </varlistentry>
 
                         <varlistentry>
+                                <term><varname>rd.weak_sysroot</varname></term>
+
+                                <listitem>
+                                        <para>Configures the sysroot.mount
+                                        logic in initrd. For details, see
+                                        <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+                                </listitem>
+                        </varlistentry>
+
+                        <varlistentry>
                                 <term><varname>modules-load=</varname></term>
                                 <term><varname>rd.modules-load=</varname></term>
 
diff --git a/man/systemd-fstab-generator.xml b/man/systemd-fstab-generator.xml
index 4bd25bf..de0ed2f 100644
--- a/man/systemd-fstab-generator.xml
+++ b/man/systemd-fstab-generator.xml
@@ -101,6 +101,16 @@
                                 the initrd.  </para></listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><varname>rd.weak_sysroot</varname></term>
+
+                                <listitem><para>If specified, systemd will
+                                ingore failures in sysroot.mount and try to
+                                continue rather than enter emergency mode.
+                                It is honored only by initial RAM disk
+                                (initrd). </para></listitem>
+                        </varlistentry>
+
                 </variablelist>
         </refsect1>
 
diff --git a/src/fstab-generator/fstab-generator.c b/src/fstab-generator/fstab-generator.c
index c17299f..449e725 100644
--- a/src/fstab-generator/fstab-generator.c
+++ b/src/fstab-generator/fstab-generator.c
@@ -492,6 +492,7 @@ static int parse_new_root_from_proc_cmdline(void) {
         char *w, *state;
         int r;
         size_t l;
+        bool weak = false;
 
         r = read_one_line_file("/proc/cmdline", &line);
         if (r < 0) {
@@ -544,6 +545,8 @@ static int parse_new_root_from_proc_cmdline(void) {
 
                         free(opts);
                         opts = o;
+                } else if (streq(word, "rd.weak_sysroot")) {
+                        weak=true;
                 }
         }
 
@@ -558,7 +561,7 @@ static int parse_new_root_from_proc_cmdline(void) {
         }
 
         log_debug("Found entry what=%s where=/sysroot type=%s", what, type);
-        r = add_mount(what, "/sysroot", type, opts, 0, false, false, false,
+        r = add_mount(what, "/sysroot", type, opts, 0, false, weak, false,
                       false, NULL, NULL, NULL, SPECIAL_INITRD_ROOT_FS_TARGET, "/proc/cmdline");
 
         return (r < 0) ? r : 0;
-- 
1.8.3.1