Add a -P option to allow skipping newfs when using a vnode-backed

disk. Apparently some people want to use mdmfs as mount_* as a
shortcut for mounting existing file-based file systems.

Note that unlike in the patches from the submitters, this option is
not available in compat mode. Compat mode was supposed to support only
things that mount_mfs used to support. To use this option from fstab,
mdmfs should be called mount_md, not mount_mfs. This distinction has
not always upkept for new options, and those can't be fixed now
without breaking people's systems, but new options should not usually
be allowed in compat mode. (Not sure why -F is allowed there at all.)

PR:		57641
Submitted by:	Ruben de Groot
Submitted independently by: Wojciech A. Koszek, for Urzad Miasta Czestochowa

2 files changed, 22 insertions, 6 deletions

diff --git a/sbin/mdmfs/mdmfs.8 b/sbin/mdmfs/mdmfs.8
index 39af0cb..3d42988 100644
--- a/sbin/mdmfs/mdmfs.8
+++ b/sbin/mdmfs/mdmfs.8
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 26, 2004
+.Dd January 2, 2006
 .Dt MDMFS 8
 .Os
 .Sh NAME
@@ -36,7 +36,7 @@
 driver
 .Sh SYNOPSIS
 .Nm
-.Op Fl DLlMNSUX
+.Op Fl DLlMNPSUX
 .Op Fl a Ar maxcontig
 .Op Fl b Ar block-size
 .Op Fl c Ar cylinders
@@ -197,6 +197,13 @@ Specify the mount options with which to mount the file system.
 See
 .Xr mount 8
 for more information.
+.It Fl P
+Preserve the existing filesystem;
+do not run
+.Xr newfs 8 .
+This only makes sense if
+.Fl F
+is specified to create a vnode-backed disk.
 .It Fl p Ar permissions
 Set the file (directory) permissions of the mount point
 .Ar mount-point
diff --git a/sbin/mdmfs/mdmfs.c b/sbin/mdmfs/mdmfs.c
index 9d4095c..33c35f9 100644
--- a/sbin/mdmfs/mdmfs.c
+++ b/sbin/mdmfs/mdmfs.c
@@ -89,7 +89,7 @@ main(int argc, char **argv)
 	    *mount_arg;
 	enum md_types mdtype;		/* The type of our memory disk. */
 	bool have_mdtype;
-	bool detach, softdep, autounit;
+	bool detach, softdep, autounit, newfs;
 	char *mtpoint, *unitstr;
 	char *p;
 	int ch;
@@ -101,6 +101,7 @@ main(int argc, char **argv)
 	detach = true;
 	softdep = true;
 	autounit = false;
+	newfs = true;
 	have_mdtype = false;
 	mdtype = MD_SWAP;
 	mdname = MD_NAME;
@@ -121,7 +122,7 @@ main(int argc, char **argv)
 		compat = true;
 
 	while ((ch = getopt(argc, argv,
-	    "a:b:Cc:Dd:e:F:f:hi:LlMm:Nn:O:o:p:Ss:t:Uv:w:X")) != -1)
+	    "a:b:Cc:Dd:e:F:f:hi:LlMm:Nn:O:o:p:PSs:t:Uv:w:X")) != -1)
 		switch (ch) {
 		case 'a':
 			argappend(&newfs_arg, "-a %s", optarg);
@@ -195,6 +196,11 @@ main(int argc, char **argv)
 		case 'o':
 			argappend(&mount_arg, "-o %s", optarg);
 			break;
+		case 'P':
+			if (compat)
+				usage();
+			newfs = false;
+			break;
 		case 'p':
 			if (compat)
 				usage();
@@ -263,6 +269,8 @@ main(int argc, char **argv)
 		mdtype = MD_SWAP;
 	if (softdep)
 		argappend(&newfs_arg, "-U");
+	if (mdtype != MD_VNODE && !newfs)
+		errx(1, "-P requires a vnode-backed disk");
 
 	/* Do the work. */
 	if (detach && !autounit)
@@ -271,7 +279,8 @@ main(int argc, char **argv)
 		do_mdconfig_attach_au(mdconfig_arg, mdtype);
 	else
 		do_mdconfig_attach(mdconfig_arg, mdtype);
-	do_newfs(newfs_arg);
+	if (newfs)
+		do_newfs(newfs_arg);
 	do_mount(mount_arg, mtpoint);
 	do_mtptsetup(mtpoint, &mi);
 
@@ -666,7 +675,7 @@ usage(void)
 		name = "mdmfs";
 	if (!compat)
 		fprintf(stderr,
-"usage: %s [-DLlMNSUX] [-a maxcontig] [-b block-size] [-c cylinders]\n"
+"usage: %s [-DLlMNPSUX] [-a maxcontig] [-b block-size] [-c cylinders]\n"
 "\t[-d rotdelay] [-e maxbpg] [-F file] [-f frag-size] [-i bytes]\n"
 "\t[-m percent-free] [-n rotational-positions] [-O optimization]\n"
 "\t[-o mount-options] [-p permissions] [-s size] [-v version]\n"