From 8f149756435998d009a8edc7206c5de038e5cbf1 Mon Sep 17 00:00:00 2001 From: Karel Zak 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= - to specify dependence an another mount (PATH is translated to unit name) x-systemd.requires= - to specify dependence on arbitrary UNIT x-systemd.requires-mounts-for= - 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 @@ + + + + Configures a Requires= and + an After= 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 + After= and Requires= in + systemd.unit5 + for details. + + + + + + Configures a + RequiresMountsFor= 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 RequiresMountsFor= in + systemd.unit5 + for details. + + 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); }