daandemeyer / rpms / systemd

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From 8f149756435998d009a8edc7206c5de038e5cbf1 Mon Sep 17 00:00:00 2001
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From: Karel Zak <kzak@redhat.com>
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Date: Mon, 18 May 2015 12:30:37 +0200
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Subject: [PATCH] fstab-generator: add x-systemd.requires and
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 x-systemd.requires-mounts-for
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Currently we have no way how to specify dependencies between fstab
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entries (or another units) in the /etc/fstab. It means that users are
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forced to bypass fstab and write .mount units manually.
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The patch introduces new systemd fstab options:
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x-systemd.requires=<PATH>
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 - to specify dependence an another mount (PATH is translated to unit name)
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x-systemd.requires=<UNIT>
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 - to specify dependence on arbitrary UNIT
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x-systemd.requires-mounts-for=<PATH ...>
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 - to specify dependence on another paths, implemented by
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   RequiresMountsFor=. The option may be specified more than once.
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For example two bind mounts where B depends on A:
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 /mnt/test/A    /mnt/test/A     none    bind,defaults
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 /mnt/test/A    /mnt/test/B     none    bind,x-systemd.requires=/mnt/test/A
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More complex example with overlay FS where one mount point depends on
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"low" and "upper" directories:
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 /dev/sdc1   /mnt/low    ext4     defaults
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 /dev/sdc2   /mnt/high   ext4     defaults
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 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
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https://bugzilla.redhat.com/show_bug.cgi?id=812826
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https://bugzilla.redhat.com/show_bug.cgi?id=1164334
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Conflicts:
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	src/fstab-generator/fstab-generator.c
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Cherry-picked from: 3519d230c8bafe834b2dac26ace49fcfba139823
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Resolves: #1164334
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---
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 man/systemd.mount.xml                 | 30 +++++++++++
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 src/fstab-generator/fstab-generator.c | 76 +++++++++++++++++++++++++++
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 src/shared/fstab-util.c               | 30 +++++++++++
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 src/shared/fstab-util.h               |  2 +
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 4 files changed, 138 insertions(+)
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diff --git a/man/systemd.mount.xml b/man/systemd.mount.xml
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index fcb9a44161..8e652e1332 100644
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--- a/man/systemd.mount.xml
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+++ b/man/systemd.mount.xml
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@@ -138,6 +138,36 @@
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     <variablelist class='fstab-options'>
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+      <varlistentry>
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+        <term><option>x-systemd.requires=</option></term>
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+
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+        <listitem><para>Configures a <varname>Requires=</varname> and
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+        an <varname>After=</varname> dependency between the created
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+        mount unit and another systemd unit, such as a device or mount
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+        unit. The argument should be a unit name, or an absolute path
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+        to a device node or mount point.  This option may be specified
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+        more than once. This option is particularly useful for mount
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+        point declarations that need an additional device to be around
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+        (such as an external journal device for journal file systems)
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+        or an additional mount to be in place (such as an overlay file
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+        system that merges multiple mount points). See
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+        <varname>After=</varname> and <varname>Requires=</varname> in
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+        <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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+        for details.</para></listitem>
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+      </varlistentry>
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+
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+      <varlistentry>
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+        <term><option>x-systemd.requires-mounts-for=</option></term>
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+
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+        <listitem><para>Configures a
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+        <varname>RequiresMountsFor=</varname> dependency between the
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+        created mount unit and other mount units. The argument must be
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+        an absolute path. This option may be specified more than once.
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+        See <varname>RequiresMountsFor=</varname> in
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+        <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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+        for details.</para></listitem>
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+       </varlistentry>
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+
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       <varlistentry>
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         <term><option>x-systemd.automount</option></term>
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diff --git a/src/fstab-generator/fstab-generator.c b/src/fstab-generator/fstab-generator.c
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index 8e2f522bd0..65ed205799 100644
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--- a/src/fstab-generator/fstab-generator.c
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+++ b/src/fstab-generator/fstab-generator.c
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@@ -155,6 +155,64 @@ static bool mount_in_initrd(struct mntent *me) {
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                streq(me->mnt_dir, "/usr");
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 }
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+static int write_requires_after(FILE *f, const char *opts) {
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+        _cleanup_strv_free_ char **names = NULL, **units = NULL;
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+        _cleanup_free_ char *res = NULL;
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+        char **s;
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+        int r;
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+
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+        assert(f);
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+        assert(opts);
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+
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+        r = fstab_extract_values(opts, "x-systemd.requires", &names);
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+        if (r < 0)
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+                return log_warning_errno(r, "Failed to parse options: %m");
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+        if (r == 0)
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+                return 0;
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+
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+        STRV_FOREACH(s, names) {
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+                char *x;
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+
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+                x = unit_name_mangle_with_suffix(*s, MANGLE_NOGLOB, ".mount");
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+                if (!x)
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+                        return log_error_errno(r, "Failed to generate unit name: %m");
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+                r = strv_consume(&units, x);
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+                if (r < 0)
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+                        return log_oom();
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+        }
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+
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+        if (units) {
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+                res = strv_join(units, " ");
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+                if (!res)
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+                        return log_oom();
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+                fprintf(f, "After=%1$s\nRequires=%1$s\n", res);
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+        }
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+
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+        return 0;
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+}
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+
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+static int write_requires_mounts_for(FILE *f, const char *opts) {
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+        _cleanup_strv_free_ char **paths = NULL;
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+        _cleanup_free_ char *res = NULL;
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+        int r;
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+
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+        assert(f);
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+        assert(opts);
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+
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+        r = fstab_extract_values(opts, "x-systemd.requires-mounts-for", &paths);
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+        if (r < 0)
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+                return log_warning_errno(r, "Failed to parse options: %m");
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+        if (r == 0)
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+                return 0;
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+
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+        res = strv_join(paths, " ");
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+        if (!res)
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+                return log_oom();
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+
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+        fprintf(f, "RequiresMountsFor=%s\n", res);
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+
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+        return 0;
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+}
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 static int add_mount(
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                 const char *what,
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                 const char *where,
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@@ -225,6 +283,15 @@ static int add_mount(
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         if (post && !noauto && !nofail && !automount)
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                 fprintf(f, "Before=%s\n", post);
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+        if (!automount && opts) {
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+                 r = write_requires_after(f, opts);
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+                 if (r < 0)
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+                         return r;
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+                 r = write_requires_mounts_for(f, opts);
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+                 if (r < 0)
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+                         return r;
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+        }
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+
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         if (passno != 0) {
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                 r = generator_write_fsck_deps(f, arg_dest, what, where, fstype);
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                 if (r < 0)
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@@ -289,6 +356,15 @@ static int add_mount(
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                                 "Before=%s\n",
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                                 post);
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+                if (opts) {
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+                        r = write_requires_after(f, opts);
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+                        if (r < 0)
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+                                return r;
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+                        r = write_requires_mounts_for(f, opts);
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+                        if (r < 0)
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+                                return r;
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+                }
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+
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                 fprintf(f,
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                         "[Automount]\n"
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                         "Where=%s\n",
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diff --git a/src/shared/fstab-util.c b/src/shared/fstab-util.c
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index cf317e17bd..e231a0ff80 100644
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--- a/src/shared/fstab-util.c
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+++ b/src/shared/fstab-util.c
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@@ -125,6 +125,36 @@ answer:
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         return !!n;
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 }
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+int fstab_extract_values(const char *opts, const char *name, char ***values) {
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+        _cleanup_strv_free_ char **optsv = NULL, **res = NULL;
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+        char **s;
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+
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+        assert(opts);
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+        assert(name);
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+        assert(values);
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+
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+        optsv = strv_split(opts, ",");
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+        if (!optsv)
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+                return -ENOMEM;
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+
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+        STRV_FOREACH(s, optsv) {
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+                char *arg;
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+                int r;
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+
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+                arg = startswith(*s, name);
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+                if (!arg || *arg != '=')
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+                        continue;
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+                r = strv_extend(&res, arg + 1);
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+                if (r < 0)
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+                        return r;
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+        }
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+
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+        *values = res;
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+        res = NULL;
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+
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+        return !!*values;
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+}
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+
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 int fstab_find_pri(const char *options, int *ret) {
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         _cleanup_free_ char *opt = NULL;
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         int r;
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diff --git a/src/shared/fstab-util.h b/src/shared/fstab-util.h
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index 9f6b32eaf4..387c562a96 100644
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--- a/src/shared/fstab-util.h
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+++ b/src/shared/fstab-util.h
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@@ -28,6 +28,8 @@
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 int fstab_filter_options(const char *opts, const char *names,
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                          const char **namefound, char **value, char **filtered);
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+int fstab_extract_values(const char *opts, const char *name, char ***values);
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+
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 static inline bool fstab_test_option(const char *opts, const char *names) {
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         return !!fstab_filter_options(opts, names, NULL, NULL, NULL);
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 }