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From 75b183700853e616362cf2f22831e1e9dc8a5515 Mon Sep 17 00:00:00 2001
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From: Harald Hoyer <harald@redhat.com>
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Date: Tue, 24 Nov 2015 09:41:26 +0100
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Subject: [PATCH] core: Do not bind a mount unit to a device, if it was from
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 mountinfo
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If a mount unit is bound to a device, systemd tries to umount the
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mount point, if it thinks the device has gone away.
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Due to the uevent queue and inotify of /proc/self/mountinfo being two
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different sources, systemd can never get the ordering reliably correct.
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It can happen, that in the uevent queue ADD,REMOVE,ADD is queued
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and an inotify of mountinfo (or libmount event) happend with the
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device in question.
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systemd cannot know, at which point of time the mount happend in the
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ADD,REMOVE,ADD sequence.
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The real ordering might have been ADD,REMOVE,ADD,mount
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and systemd might think ADD,mount,REMOVE,ADD and would umount the
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mountpoint.
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A test script which triggered this behaviour is:
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rm -f test-efi-disk.img
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dd if=/dev/null of=test-efi-disk.img bs=1M seek=512 count=1
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parted --script test-efi-disk.img \
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  "mklabel gpt" \
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  "mkpart ESP fat32 1MiB 511MiB" \
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  "set 1 boot on"
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LOOP=$(losetup --show -f -P test-efi-disk.img)
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udevadm settle
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mkfs.vfat -F32 ${LOOP}p1
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mkdir -p mnt
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mount ${LOOP}p1 mnt
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... <dostuffwith mnt>
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Without the "udevadm settle" systemd unmounted mnt while the script was
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operating on mnt.
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Of course the question is, why there was a REMOVE in the first place,
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but this is not part of this patch.
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Cherry-picked from: 9d06297e262966de71095debd1537fc223f940a3
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Resolves: #1283579
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---
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 src/core/mount.c  | 2 +-
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 src/core/socket.c | 2 +-
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 src/core/swap.c   | 2 +-
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 src/core/unit.c   | 4 ++--
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 src/core/unit.h   | 2 +-
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 5 files changed, 6 insertions(+), 6 deletions(-)
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diff --git a/src/core/mount.c b/src/core/mount.c
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index 1f1a41a..23f63ce 100644
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--- a/src/core/mount.c
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+++ b/src/core/mount.c
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@@ -321,7 +321,7 @@ static int mount_add_device_links(Mount *m) {
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         if (mount_is_auto(p) && UNIT(m)->manager->running_as == SYSTEMD_SYSTEM)
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                 device_wants_mount = true;
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-        r = unit_add_node_link(UNIT(m), p->what, device_wants_mount);
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+        r = unit_add_node_link(UNIT(m), p->what, device_wants_mount, m->from_fragment ? UNIT_BINDS_TO : UNIT_REQUIRES);
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         if (r < 0)
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                 return r;
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diff --git a/src/core/socket.c b/src/core/socket.c
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index 7022e77..bc677a2 100644
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--- a/src/core/socket.c
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+++ b/src/core/socket.c
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@@ -267,7 +267,7 @@ static int socket_add_device_link(Socket *s) {
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                 return 0;
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         t = strjoina("/sys/subsystem/net/devices/", s->bind_to_device);
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-        return unit_add_node_link(UNIT(s), t, false);
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+        return unit_add_node_link(UNIT(s), t, false, UNIT_BINDS_TO);
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 }
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 static int socket_add_default_dependencies(Socket *s) {
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diff --git a/src/core/swap.c b/src/core/swap.c
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index 369abf0..34a2c40 100644
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--- a/src/core/swap.c
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+++ b/src/core/swap.c
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@@ -201,7 +201,7 @@ static int swap_add_device_links(Swap *s) {
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                 return 0;
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         if (is_device_path(s->what))
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-                return unit_add_node_link(UNIT(s), s->what, UNIT(s)->manager->running_as == SYSTEMD_SYSTEM);
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+                return unit_add_node_link(UNIT(s), s->what, UNIT(s)->manager->running_as == SYSTEMD_SYSTEM, UNIT_BINDS_TO);
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         else
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                 /* File based swap devices need to be ordered after
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                  * systemd-remount-fs.service, since they might need a
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diff --git a/src/core/unit.c b/src/core/unit.c
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index fa17567..ae47a28 100644
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--- a/src/core/unit.c
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+++ b/src/core/unit.c
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@@ -2823,7 +2823,7 @@ int unit_deserialize(Unit *u, FILE *f, FDSet *fds) {
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         }
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 }
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-int unit_add_node_link(Unit *u, const char *what, bool wants) {
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+int unit_add_node_link(Unit *u, const char *what, bool wants, UnitDependency dep) {
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         Unit *device;
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         _cleanup_free_ char *e = NULL;
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         int r;
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@@ -2850,7 +2850,7 @@ int unit_add_node_link(Unit *u, const char *what, bool wants) {
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         if (r < 0)
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                 return r;
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-        r = unit_add_two_dependencies(u, UNIT_AFTER, u->manager->running_as == SYSTEMD_SYSTEM ? UNIT_BINDS_TO : UNIT_WANTS, device, true);
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+        r = unit_add_two_dependencies(u, UNIT_AFTER, u->manager->running_as == SYSTEMD_SYSTEM ? dep : UNIT_WANTS, device, true);
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         if (r < 0)
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                 return r;
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diff --git a/src/core/unit.h b/src/core/unit.h
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index 7ebc489..0eebc0b 100644
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--- a/src/core/unit.h
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+++ b/src/core/unit.h
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@@ -548,7 +548,7 @@ void unit_serialize_item_format(Unit *u, FILE *f, const char *key, const char *v
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 void unit_serialize_item(Unit *u, FILE *f, const char *key, const char *value);
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 int unit_deserialize(Unit *u, FILE *f, FDSet *fds);
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-int unit_add_node_link(Unit *u, const char *what, bool wants);
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+int unit_add_node_link(Unit *u, const char *what, bool wants, UnitDependency d);
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 int unit_coldplug(Unit *u, Hashmap *deferred_work);
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