mount: cleanup "none" fstype usage

 * disable to call /sbin/mount.none
 * rewrite fstype to "none" for MS_BIND and MS_MOVE
 * add notes about "none" to fstab.5 and mount.8

Signed-off-by: Karel Zak <kzak@redhat.com>

4 files changed, 18 insertions, 4 deletions

diff --git a/mount/fstab.5 b/mount/fstab.5
index a7978b5f5..6109b5ee4 100644
--- a/mount/fstab.5
+++ b/mount/fstab.5
@@ -142,6 +142,9 @@ An entry
 .I ignore
 causes the line to be ignored.  This is useful
 to show disk partitions which are currently unused.
+An entry
+.I none
+is useful for bind or move mounts.
 
 The fourth field,
 .RI ( fs_mntops ),
diff --git a/mount/mount.8 b/mount/mount.8
index 01001ade5..54b11d469 100644
--- a/mount/mount.8
+++ b/mount/mount.8
@@ -108,6 +108,11 @@ file hierarchy somewhere else. The call is
 .br
 .B "mount --bind olddir newdir"
 .RE
+or fstab entry is:
+.RS
+.br
+.B "/olddir  /newdir  none  bind"
+.RE
 After this call the same contents is accessible in two places.
 One can also remount a single file (on a single file).
 
diff --git a/mount/mount.c b/mount/mount.c
index 5bc2b30c3..2e458cad0 100644
--- a/mount/mount.c
+++ b/mount/mount.c
@@ -624,7 +624,10 @@ check_special_mountprog(const char *spec, const char *node, const char *type, in
   if (!external_allowed)
       return 0;
 
-  if (type && strlen(type) < 100) {
+  if (type == NULL || strcmp(type, "none") == 0)
+	  return 0;
+
+  if (strlen(type) < 100) {
        sprintf(mountprog, "/sbin/mount.%s", type);
        if (stat(mountprog, &statbuf) == 0) {
 	    if (verbose)
@@ -719,8 +722,8 @@ guess_fstype_and_mount(const char *spec, const char *node, const char **types,
    if (*types && strcasecmp (*types, "auto") == 0)
       *types = NULL;
 
-   if (!*types && (flags & (MS_BIND | MS_MOVE)))
-      *types = "none";		/* random, but not "bind" */
+   if (flags & (MS_BIND | MS_MOVE))
+      *types = "none";
 
    if (!*types && !(flags & MS_REMOUNT)) {
       *types = guess_fstype_by_devname(spec);
diff --git a/mount/umount.c b/mount/umount.c
index 322161983..6af43546e 100644
--- a/mount/umount.c
+++ b/mount/umount.c
@@ -94,7 +94,10 @@ check_special_umountprog(const char *spec, const char *node,
 	if (!external_allowed)
 		return 0;
 
-	if (type && strlen(type) < 100) {
+	if (type == NULL || strcmp(type, "none") == 0)
+		return 0;
+
+	if (strlen(type) < 100) {
 		sprintf(umountprog, "/sbin/umount.%s", type);
 		if (stat(umountprog, &statbuf) == 0) {
 			res = fork();