umount: add info that --all-targets works with mtab symlink only

Reported-by: Ruediger Meier <sweet_f_a@gmx.de>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/umount.8 b/sys-utils/umount.8
index 94a13f77dbe20a46d90ec88402770ceef34e7ed0..c9e2aca960246bba957c9be077e3fe1648492ade 100644 (file)
--- a/sys-utils/umount.8
+++ b/sys-utils/umount.8
@@ -70,7 +70,9 @@ filesystem is not unmounted.)
 Unmount all mountpoints in the current namespace for the specified filesystem.
 The filesystem could be specified by one of the mountpoints or device name (or
 UUID, etc.). This option could be used together with \fB\-\-recursive\fR then
-all nested mounts within the filesystem are recursively unmounted.
+all nested mounts within the filesystem are recursively unmounted. The 
+\fB\-\-all-targets\fR is only supported on systems where /etc/mtab is a symlink
+to /proc/mounts.
 .TP
 \fB\-c\fR, \fB\-\-no\-canonicalize\fR
 Do not canonicalize paths.  For more details about this option see the

diff --git a/sys-utils/umount.c b/sys-utils/umount.c
index 0d576595b68351ade96105471659a50cafda7c2b..1ad9e6aeb990cc210efc12f7abc3d25b3d245b88 100644 (file)
--- a/sys-utils/umount.c
+++ b/sys-utils/umount.c
@@ -435,7 +435,9 @@ static int umount_alltargets(struct libmnt_context *cxt, const char *spec, int r
                return mk_exit_code(cxt, rc);           /* error */
 
        if (!mnt_fs_get_srcpath(fs) || !mnt_fs_get_devno(fs))
-               err(MOUNT_EX_USAGE, _("%s: failed to determine source"), spec);
+               errx(MOUNT_EX_USAGE, _("%s: failed to determine source "
+                               "(--all-targets is unsupported on systems with "
+                               "regular mtab file)."), spec);
 
        itr = mnt_new_iter(MNT_ITER_BACKWARD);
        if (!itr)