umount: Don't use options from fstab on remount

The fstab entry may contain comment/application-specific options, like
for example x-systemd.automount or x-initrd.mount.

With the recent switch to libmount, the mount options during remount are
now gathered via mnt_fs_get_options(), which returns the merged fstab
options with the effective options in mountinfo.

Unfortunately if one of these application-specific options are set in
fstab, the remount will fail with -EINVAL.

In systemd 238:

  Remounting '/test-x-initrd-mount' read-only in with options
  'errors=continue,user_xattr,acl'.

In systemd 239:

  Remounting '/test-x-initrd-mount' read-only in with options
  'errors=continue,user_xattr,acl,x-initrd.mount'.
  Failed to remount '/test-x-initrd-mount' read-only: Invalid argument

So instead of using mnt_fs_get_options(), we're now using both
mnt_fs_get_fs_options() and mnt_fs_get_vfs_options() and merging the
results together so we don't get any non-relevant options from fstab.

Signed-off-by: aszlig <aszlig@nix.build>

1 files changed, 19 insertions, 2 deletions

diff --git a/src/core/umount.c b/src/core/umount.c
index 241fe6fc62..8ed1074073 100644
--- a/src/core/umount.c
+++ b/src/core/umount.c
@@ -72,7 +72,8 @@ int mount_points_list_get(const char *mountinfo, MountPoint **head) {
 
         for (;;) {
                 struct libmnt_fs *fs;
-                const char *path, *options, *fstype;
+                const char *path, *fstype;
+                _cleanup_free_ char *options = NULL;
                 _cleanup_free_ char *p = NULL;
                 unsigned long remount_flags = 0u;
                 _cleanup_free_ char *remount_options = NULL;
@@ -92,9 +93,25 @@ int mount_points_list_get(const char *mountinfo, MountPoint **head) {
                 if (cunescape(path, UNESCAPE_RELAX, &p) < 0)
                         return log_oom();
 
-                options = mnt_fs_get_options(fs);
                 fstype = mnt_fs_get_fstype(fs);
 
+                /* Combine the generic VFS options with the FS-specific
+                 * options. Duplicates are not a problem here, because the only
+                 * options that should come up twice are typically ro/rw, which
+                 * are turned into MS_RDONLY or the invertion of it.
+                 *
+                 * Even if there are duplicates later in mount_option_mangle()
+                 * it shouldn't hurt anyways as they override each other.
+                 */
+                if (!strextend_with_separator(&options, ",",
+                                              mnt_fs_get_vfs_options(fs),
+                                              NULL))
+                        return log_oom();
+                if (!strextend_with_separator(&options, ",",
+                                              mnt_fs_get_fs_options(fs),
+                                              NULL))
+                        return log_oom();
+
                 /* Ignore mount points we can't unmount because they
                  * are API or because we are keeping them open (like
                  * /dev/console). Also, ignore all mounts below API