Control: forwarded -1 https://github.com/systemd/systemd/issues/4810

This was fixed upstream by
https://github.com/systemd/systemd/commit/ad2706db7cceba69203f3ac2b6ef65d7490c5f29

Attached is a backport of that patch for v215

It seems to fix the issue seen on jessie.
-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?
From: Lennart Poettering <lenn...@poettering.net>
Date: Tue, 29 Nov 2016 22:50:21 +0100
Subject: core: rework logic to determine when we decide to add automatic deps
 for mounts

This adds a concept of "extrinsic" mounts. If mounts are extrinsic we consider
them managed by something else and do not add automatic ordering against
umount.target, local-fs.target, remote-fs.target.

Extrinsic mounts are considered:

- All mounts if we are running in --user mode

- API mounts such as everything below /proc, /sys, /dev, which exist from
  earliest boot to latest shutdown.

- All mounts marked as initrd mounts, if we run on the host

- The initrd's private directory /run/initrams that should survive until last
  reboot.

This primarily merges a couple of different exclusion lists into a single
concept.

(cherry picked from commit ad2706db7cceba69203f3ac2b6ef65d7490c5f29)
---
 src/core/mount.c       | 62 +++++++++++++++++++++++++++++++-------------------
 src/shared/path-util.h | 25 ++++++++++++++++++++
 2 files changed, 64 insertions(+), 23 deletions(-)

diff --git a/src/core/mount.c b/src/core/mount.c
index 102bbef91..44f79ba8a 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -350,19 +350,35 @@ static int mount_add_quota_links(Mount *m) {
         return 0;
 }
 
-static bool should_umount(Mount *m) {
+static bool mount_is_extrinsic(Mount *m) {
         MountParameters *p;
+        assert(m);
 
-        if (path_equal(m->where, "/") ||
-            path_equal(m->where, "/usr"))
-                return false;
+        /* Returns true for all units that are "magic" and should be excluded from the usual start-up and shutdown
+         * dependencies. We call them "extrinsic" here, as they are generally mounted outside of the systemd dependency
+         * logic. We shouldn't attempt to manage them ourselves but it's fine if the user operates on them with us. */
+
+        if (UNIT(m)->manager->running_as != SYSTEMD_SYSTEM) /* We only automatically manage mounts if we are in system mode */
+                return true;
 
+        if (PATH_IN_SET(m->where,  /* Don't bother with the OS data itself */
+                        "/",
+                        "/usr"))
+                return true;
+
+        if (PATH_STARTSWITH_SET(m->where,
+                                "/run/initramfs",    /* This should stay around from before we boot until after we shutdown */
+                                "/proc",             /* All of this is API VFS */
+                                "/sys",              /* … dito … */
+                                "/dev"))             /* … dito … */
+                return true;
+
+        /* If this is an initrd mount, and we are not in the initrd, then leave this around forever, too. */
         p = get_mount_parameters(m);
-        if (p && mount_test_option(p->options, "x-initrd.mount") &&
-            !in_initrd())
-                return false;
+        if (p && mount_test_option(p->options, "x-initrd.mount") && !in_initrd())
+                return true;
 
-        return true;
+        return false;
 }
 
 static int mount_add_default_dependencies(Mount *m) {
@@ -375,14 +391,17 @@ static int mount_add_default_dependencies(Mount *m) {
         if (UNIT(m)->manager->running_as != SYSTEMD_SYSTEM)
                 return 0;
 
+        /* We do not add any default dependencies to /, /usr or /run/initramfs/, since they are guaranteed to stay
+         * mounted the whole time, since our system is on it.  Also, don't bother with anything mounted below virtual
+         * file systems, it's also going to be virtual, and hence not worth the effort. */
+        if (mount_is_extrinsic(m))
+                return 0;
+
         p = get_mount_parameters(m);
 
         if (!p)
                 return 0;
 
-        if (path_equal(m->where, "/"))
-                return 0;
-
         if (mount_is_network(p)) {
                 after = SPECIAL_REMOTE_FS_PRE_TARGET;
                 after2 = SPECIAL_NETWORK_TARGET;
@@ -409,11 +428,9 @@ static int mount_add_default_dependencies(Mount *m) {
                         return r;
         }
 
-        if (should_umount(m)) {
-                r = unit_add_two_dependencies_by_name(UNIT(m), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, NULL, true);
-                if (r < 0)
-                        return r;
-        }
+        r = unit_add_two_dependencies_by_name(UNIT(m), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, NULL, true);
+        if (r < 0)
+                return r;
 
         return 0;
 }
@@ -667,6 +684,7 @@ static void mount_dump(Unit *u, FILE *f, const char *prefix) {
                 "%sOptions: %s\n"
                 "%sFrom /proc/self/mountinfo: %s\n"
                 "%sFrom fragment: %s\n"
+                "%sExtrinsic: %s\n"
                 "%sDirectoryMode: %04o\n",
                 prefix, mount_state_to_string(m->state),
                 prefix, mount_result_to_string(m->result),
@@ -676,6 +694,7 @@ static void mount_dump(Unit *u, FILE *f, const char *prefix) {
                 prefix, p ? strna(p->options) : "n/a",
                 prefix, yes_no(m->from_proc_self_mountinfo),
                 prefix, yes_no(m->from_fragment),
+                prefix, yes_no(mount_is_extrinsic(m)),
                 prefix, m->directory_mode);
 
         if (m->control_pid > 0)
@@ -1374,8 +1393,7 @@ static int mount_add_one(
                         goto fail;
                 }
 
-
-                if (m->running_as == SYSTEMD_SYSTEM) {
+                if (!mount_is_extrinsic(MOUNT(u))) {
                         const char* target;
 
                         target = fstype_is_network(fstype) ? SPECIAL_REMOTE_FS_TARGET : SPECIAL_LOCAL_FS_TARGET;
@@ -1384,11 +1402,9 @@ static int mount_add_one(
                         if (r < 0)
                                 goto fail;
 
-                        if (should_umount(MOUNT(u))) {
-                                r = unit_add_dependency_by_name(u, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, NULL, true);
-                                if (r < 0)
-                                        goto fail;
-                        }
+                        r = unit_add_dependency_by_name(u, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, NULL, true);
+                        if (r < 0)
+                                goto fail;
                 }
 
                 unit_add_to_load_queue(u);
diff --git a/src/shared/path-util.h b/src/shared/path-util.h
index 54f00a8a8..6ac8eb9e2 100644
--- a/src/shared/path-util.h
+++ b/src/shared/path-util.h
@@ -70,3 +70,28 @@ int fsck_exists(const char *fstype);
 /* Same as PATH_FOREACH_PREFIX but also includes the specified path itself */
 #define PATH_FOREACH_PREFIX_MORE(prefix, path) \
         for (char *_slash = ({ path_kill_slashes(strcpy(prefix, path)); if (streq(prefix, "/")) prefix[0] = 0; strrchr(prefix, 0); }); _slash && !(*_slash = 0); _slash = strrchr((prefix), '/'))
+
+/* Note: the search terminates on the first NULL item. */
+#define PATH_IN_SET(p, ...)                                     \
+        ({                                                      \
+                char **s;                                       \
+                bool _found = false;                            \
+                STRV_FOREACH(s, STRV_MAKE(__VA_ARGS__))         \
+                        if (path_equal(p, *s)) {                \
+                               _found = true;                   \
+                               break;                           \
+                        }                                       \
+                _found;                                         \
+        })
+
+#define PATH_STARTSWITH_SET(p, ...)                             \
+        ({                                                      \
+                char **s;                                       \
+                bool _found = false;                            \
+                STRV_FOREACH(s, STRV_MAKE(__VA_ARGS__))         \
+                        if (path_startswith(p, *s)) {           \
+                               _found = true;                   \
+                               break;                           \
+                        }                                       \
+                _found;                                         \
+        })

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