Do not fail on ENOENT

Introduces a new mount option "nofail" which prevents mount
to fail if the device does not exist.

Signed-off-by: Matthias Koenig <mkoenig@suse.de>

Index: util-linux-ng-2.13-rc1/mount/mount.8
===================================================================
--- util-linux-ng-2.13-rc1.orig/mount/mount.8
+++ util-linux-ng-2.13-rc1/mount/mount.8
@@ -625,6 +625,9 @@ access on the news spool to speed up new
 .B nodiratime
 Do not update directory inode access times on this filesystem.
 .TP
+.B nofail
+Do not report errors for this device if it does not exist.
+.TP
 .B relatime
 Update inode access times relative to modify or change time.  Access
 time is only updated if the previous access time was earlier than the
Index: util-linux-ng-2.13-rc1/mount/mount.c
===================================================================
--- util-linux-ng-2.13-rc1.orig/mount/mount.c
+++ util-linux-ng-2.13-rc1/mount/mount.c
@@ -182,9 +182,12 @@ static const struct opt_map opt_map[] = 
   { "norelatime", 0, 1, MS_RELATIME }, /* Update access time without regard
 					  to mtime/ctime */
 #endif
+  { "nofail",	0, 0, MS_COMMENT},	/* Do not fail if ENOENT on dev */
   { NULL,	0, 0, 0		}
 };
 
+static int opt_nofail = 0;
+
 static const char *opt_loopdev, *opt_vfstype, *opt_offset, *opt_encryption,
 	*opt_speed, *opt_comment, *opt_uhelper;
 
@@ -389,6 +392,8 @@ parse_opt(char *opt, int *mask, char **e
 				verbose = 0;
 			}
 #endif
+			if (streq(opt, "nofail"))
+				opt_nofail = 1;
 			return;
 		}
 
@@ -1150,9 +1155,11 @@ try_mount_one (const char *spec0, const 
       else if (stat (node, &statbuf))
 	   error (_("mount: mount point %s is a symbolic link to nowhere"),
 		  node);
-      else if (stat (spec, &statbuf))
+      else if (stat (spec, &statbuf)) {
+	   if (opt_nofail)
+		goto out;
 	   error (_("mount: special device %s does not exist"), spec);
-      else {
+      } else {
 	   errno = mnt_err;
 	   perror("mount");
       }