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From 8f149756435998d009a8edc7206c5de038e5cbf1 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Mon, 18 May 2015 12:30:37 +0200
Subject: [PATCH] fstab-generator: add x-systemd.requires and
x-systemd.requires-mounts-for
Currently we have no way how to specify dependencies between fstab
entries (or another units) in the /etc/fstab. It means that users are
forced to bypass fstab and write .mount units manually.
The patch introduces new systemd fstab options:
x-systemd.requires=<PATH>
- to specify dependence an another mount (PATH is translated to unit name)
x-systemd.requires=<UNIT>
- to specify dependence on arbitrary UNIT
x-systemd.requires-mounts-for=<PATH ...>
- to specify dependence on another paths, implemented by
RequiresMountsFor=. The option may be specified more than once.
For example two bind mounts where B depends on A:
/mnt/test/A /mnt/test/A none bind,defaults
/mnt/test/A /mnt/test/B none bind,x-systemd.requires=/mnt/test/A
More complex example with overlay FS where one mount point depends on
"low" and "upper" directories:
/dev/sdc1 /mnt/low ext4 defaults
/dev/sdc2 /mnt/high ext4 defaults
overlay /mnt/merged overlay lowerdir=/mnt/low,upperdir=/mnt/high/data,workdir=/mnt/high/work,x-systemd.requires-mounts-for=/mnt/low,x-systemd.requires-mounts-for=mnt/high
https://bugzilla.redhat.com/show_bug.cgi?id=812826
https://bugzilla.redhat.com/show_bug.cgi?id=1164334
Conflicts:
src/fstab-generator/fstab-generator.c
Cherry-picked from: 3519d230c8bafe834b2dac26ace49fcfba139823
Resolves: #1164334
---
man/systemd.mount.xml | 30 ++++++++++++++
src/fstab-generator/fstab-generator.c | 76 +++++++++++++++++++++++++++++++++++
src/shared/fstab-util.c | 30 ++++++++++++++
src/shared/fstab-util.h | 2 +
4 files changed, 138 insertions(+)
diff --git a/man/systemd.mount.xml b/man/systemd.mount.xml
index fcb9a4416..8e652e133 100644
--- a/man/systemd.mount.xml
+++ b/man/systemd.mount.xml
@@ -138,6 +138,36 @@
<variablelist class='fstab-options'>
+ <varlistentry>
+ <term><option>x-systemd.requires=</option></term>
+
+ <listitem><para>Configures a <varname>Requires=</varname> and
+ an <varname>After=</varname> dependency between the created
+ mount unit and another systemd unit, such as a device or mount
+ unit. The argument should be a unit name, or an absolute path
+ to a device node or mount point. This option may be specified
+ more than once. This option is particularly useful for mount
+ point declarations that need an additional device to be around
+ (such as an external journal device for journal file systems)
+ or an additional mount to be in place (such as an overlay file
+ system that merges multiple mount points). See
+ <varname>After=</varname> and <varname>Requires=</varname> in
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>x-systemd.requires-mounts-for=</option></term>
+
+ <listitem><para>Configures a
+ <varname>RequiresMountsFor=</varname> dependency between the
+ created mount unit and other mount units. The argument must be
+ an absolute path. This option may be specified more than once.
+ See <varname>RequiresMountsFor=</varname> in
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>x-systemd.automount</option></term>
diff --git a/src/fstab-generator/fstab-generator.c b/src/fstab-generator/fstab-generator.c
index 8e2f522bd..65ed20579 100644
--- a/src/fstab-generator/fstab-generator.c
+++ b/src/fstab-generator/fstab-generator.c
@@ -155,6 +155,64 @@ static bool mount_in_initrd(struct mntent *me) {
streq(me->mnt_dir, "/usr");
}
+static int write_requires_after(FILE *f, const char *opts) {
+ _cleanup_strv_free_ char **names = NULL, **units = NULL;
+ _cleanup_free_ char *res = NULL;
+ char **s;
+ int r;
+
+ assert(f);
+ assert(opts);
+
+ r = fstab_extract_values(opts, "x-systemd.requires", &names);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to parse options: %m");
+ if (r == 0)
+ return 0;
+
+ STRV_FOREACH(s, names) {
+ char *x;
+
+ x = unit_name_mangle_with_suffix(*s, MANGLE_NOGLOB, ".mount");
+ if (!x)
+ return log_error_errno(r, "Failed to generate unit name: %m");
+ r = strv_consume(&units, x);
+ if (r < 0)
+ return log_oom();
+ }
+
+ if (units) {
+ res = strv_join(units, " ");
+ if (!res)
+ return log_oom();
+ fprintf(f, "After=%1$s\nRequires=%1$s\n", res);
+ }
+
+ return 0;
+}
+
+static int write_requires_mounts_for(FILE *f, const char *opts) {
+ _cleanup_strv_free_ char **paths = NULL;
+ _cleanup_free_ char *res = NULL;
+ int r;
+
+ assert(f);
+ assert(opts);
+
+ r = fstab_extract_values(opts, "x-systemd.requires-mounts-for", &paths);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to parse options: %m");
+ if (r == 0)
+ return 0;
+
+ res = strv_join(paths, " ");
+ if (!res)
+ return log_oom();
+
+ fprintf(f, "RequiresMountsFor=%s\n", res);
+
+ return 0;
+}
static int add_mount(
const char *what,
const char *where,
@@ -225,6 +283,15 @@ static int add_mount(
if (post && !noauto && !nofail && !automount)
fprintf(f, "Before=%s\n", post);
+ if (!automount && opts) {
+ r = write_requires_after(f, opts);
+ if (r < 0)
+ return r;
+ r = write_requires_mounts_for(f, opts);
+ if (r < 0)
+ return r;
+ }
+
if (passno != 0) {
r = generator_write_fsck_deps(f, arg_dest, what, where, fstype);
if (r < 0)
@@ -289,6 +356,15 @@ static int add_mount(
"Before=%s\n",
post);
+ if (opts) {
+ r = write_requires_after(f, opts);
+ if (r < 0)
+ return r;
+ r = write_requires_mounts_for(f, opts);
+ if (r < 0)
+ return r;
+ }
+
fprintf(f,
"[Automount]\n"
"Where=%s\n",
diff --git a/src/shared/fstab-util.c b/src/shared/fstab-util.c
index cf317e17b..e231a0ff8 100644
--- a/src/shared/fstab-util.c
+++ b/src/shared/fstab-util.c
@@ -125,6 +125,36 @@ answer:
return !!n;
}
+int fstab_extract_values(const char *opts, const char *name, char ***values) {
+ _cleanup_strv_free_ char **optsv = NULL, **res = NULL;
+ char **s;
+
+ assert(opts);
+ assert(name);
+ assert(values);
+
+ optsv = strv_split(opts, ",");
+ if (!optsv)
+ return -ENOMEM;
+
+ STRV_FOREACH(s, optsv) {
+ char *arg;
+ int r;
+
+ arg = startswith(*s, name);
+ if (!arg || *arg != '=')
+ continue;
+ r = strv_extend(&res, arg + 1);
+ if (r < 0)
+ return r;
+ }
+
+ *values = res;
+ res = NULL;
+
+ return !!*values;
+}
+
int fstab_find_pri(const char *options, int *ret) {
_cleanup_free_ char *opt = NULL;
int r;
diff --git a/src/shared/fstab-util.h b/src/shared/fstab-util.h
index 9f6b32eaf..387c562a9 100644
--- a/src/shared/fstab-util.h
+++ b/src/shared/fstab-util.h
@@ -28,6 +28,8 @@
int fstab_filter_options(const char *opts, const char *names,
const char **namefound, char **value, char **filtered);
+int fstab_extract_values(const char *opts, const char *name, char ***values);
+
static inline bool fstab_test_option(const char *opts, const char *names) {
return !!fstab_filter_options(opts, names, NULL, NULL, NULL);
}