1 files changed, 14 insertions, 8 deletions

diff --git a/util-linux/umount.c b/util-linux/umount.c
index 24c1d03a9..fabc3d049 100644
--- a/util-linux/umount.c
+++ b/util-linux/umount.c
@@ -78,6 +78,7 @@ int umount_main(int argc, char **argv)
         // Loop through everything we're supposed to umount, and do so.
         for (;;) {
                 int curstat;
+                char *zapit = *argv;
 
                 // Do we already know what to umount this time through the loop?
                 if (m) safe_strncpy(path, m->dir, PATH_MAX);
@@ -86,32 +87,37 @@ int umount_main(int argc, char **argv)
                 // Get next command line argument (and look it up in mtab list)
                 else if (!argc--) break;
                 else {
-                        realpath(*argv++, path);
+                        argv++;
+                        realpath(zapit, path);
                         for (m = mtl; m; m = m->next)
                                 if (!strcmp(path, m->dir) || !strcmp(path, m->device))
                                         break;
                 }
+                // If we couldn't find this sucker in /etc/mtab, punt by passing our
+                // command line argument straight to the umount syscall.  Otherwise,
+                // umount the directory even if we were given the block device.
+                if (m) zapit = m->dir;
 
                 // Let's ask the thing nicely to unmount.
-                curstat = umount(path);
+                curstat = umount(zapit);
 
                 // Force the unmount, if necessary.
                 if (curstat && doForce) {
-                        curstat = umount2(path, doForce);
+                        curstat = umount2(zapit, doForce);
                         if (curstat)
-                                bb_error_msg_and_die("forced umount of %s failed!", path);
+                                bb_error_msg_and_die("forced umount of %s failed!", zapit);
                 }
 
                 // If still can't umount, maybe remount read-only?
                 if (curstat && (opt & OPT_REMOUNT) && errno == EBUSY && m) {
-                        curstat = mount(m->device, path, NULL, MS_REMOUNT|MS_RDONLY, NULL);
+                        curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
                         bb_error_msg(curstat ? "Cannot remount %s read-only" :
                                                  "%s busy - remounted read-only", m->device);
                 }
 
                 if (curstat) {
                         status = EXIT_FAILURE;
-                        bb_perror_msg("Couldn't umount %s", path);
+                        bb_perror_msg("Couldn't umount %s", zapit);
                 } else {
                         /* De-allocate the loop device.  This ioctl should be ignored on
                          * any non-loop block devices. */
@@ -121,9 +127,9 @@ int umount_main(int argc, char **argv)
                                 erase_mtab(m->dir);
                 }
 
-
-
                 // Find next matching mtab entry for -a or umount /dev
+                // Note this means that "umount /dev/blah" will unmount all instances
+                // of /dev/blah, not just the most recent.
                 while (m && (m = m->next))
                         if ((opt & OPT_ALL) || !strcmp(path,m->device))
                                 break;