If we are mounting the root filesystem, and we're accessing it through

something that might refer to the compatability slice rather than the
correct slice entry, try all the possible slice entries first.

This is a compatability hack to deal with the case where the kernel has
correctly mounted the root filesystem out of its slice, but the user
has not updated their /etc/fstab file to reflect this.  A diagnostic
is emitted if the mount succeeds, indicating that the file should be
updated.

This is a prelude to fixing the kernel to behave as alluded to above.
Reviewed by:	(discussed with) julian, phk

2 files changed, 38 insertions, 3 deletions

diff --git a/sbin/mount_ifs/Makefile b/sbin/mount_ifs/Makefile
index df4ebcf..e899d4e 100644
--- a/sbin/mount_ifs/Makefile
+++ b/sbin/mount_ifs/Makefile
@@ -1,9 +1,12 @@
 #	@(#)Makefile	8.6 (Berkeley) 5/8/95
-#	$Id: Makefile,v 1.5 1997/08/25 20:38:35 bde Exp $
+#	$Id: Makefile,v 1.6 1998/01/20 10:39:57 bde Exp $
 
 PROG=	mount
 SRCS=	mount.c mount_ufs.c getmntopts.c vfslist.c
 MAN8=	mount.8
 # We do NOT install the getmntopts.3 man page.
 
+# We support the ROOTSLICE_HUNT hack
+CFLAGS+=-DROOTSLICE_HUNT
+
 .include <bsd.prog.mk>
diff --git a/sbin/mount_ifs/mount_ufs.c b/sbin/mount_ifs/mount_ufs.c
index f40fe32..cefdd96 100644
--- a/sbin/mount_ifs/mount_ufs.c
+++ b/sbin/mount_ifs/mount_ufs.c
@@ -42,7 +42,7 @@ static const char copyright[] =
 static char sccsid[] = "@(#)mount_ufs.c	8.4 (Berkeley) 4/26/95";
 #else
 static const char rcsid[] =
-	"$Id: mount_ufs.c,v 1.9 1997/08/24 21:02:50 steve Exp $";
+	"$Id: mount_ufs.c,v 1.10 1997/08/25 21:14:22 bde Exp $";
 #endif
 #endif /* not lint */
 
@@ -83,6 +83,10 @@ mount_ufs(argc, argv)
 	char *fs_name;
 	struct vfsconf vfc;
 	int error = 0;
+#ifdef ROOTSLICE_HUNT
+	int slice, part, result;
+	char devbuf[MAXPATHLEN], devpfx[MAXPATHLEN];
+#endif
 
 	mntflags = 0;
 	optind = optreset = 1;		/* Reset for parse of new argv. */
@@ -124,8 +128,36 @@ mount_ufs(argc, argv)
 		warnx("ufs filesystem is not available");
 		return (1);
 	}
-
+#ifdef ROOTSLICE_HUNT
+	result = -1;
+	/*
+	 * If we are mounting root, and we have a mount of something that
+	 * might be the compatability slice, try mounting other slices
+	 * first.  If the kernel has done the right thing and mounted
+	 * the slice because the disk is really sliced, this will find
+	 * the real root filesystem.  If not, we'll try what was supplied.
+	 */
+	if (!strcmp(fs_name, "/") &&
+	    (sscanf(args.fspec, "%[^0-9]%d%c", devpfx, &unit, &part) == 3) &&
+	    (part >= 'a') &&
+	    (part <= 'h')) {
+		for (slice = 1; (slice < 32) && (result < 0); slice++) {
+			sprintf(devbuf, "%s%ds%d%c",
+				devpfx, unit, slice, part);
+			args.fspec = devbuf;
+			result = mount(vfc.vfc_name, fs_name, mntflags, &args);
+		}
+		args.fspec = argv[0];
+	}
+	if (result == 0)
+		warnx("*** update /etc/fstab entry for %s to use %s ***",
+			fs_name, devbuf);
+	/* Try the mount as originally requested */
+	if ((result  < 0) &&
+	    (mount(vfc.vfc_name, fs_name, mntflags, &args < 0)) {
+#else
 	if (mount(vfc.vfc_name, fs_name, mntflags, &args) < 0) {
+#endif
 		(void)fprintf(stderr, "%s on %s: ", args.fspec, fs_name);
 		switch (errno) {
 		case EMFILE: