enhacement to mdmfs

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Date: Tue, 30 Nov 2004 12:21:35 +0100
To: freebsd-current@freebsd.org

Hello,

I've recently shot my foot with mdmfs. Of course it was a pilot error but
the funcioanility I was looking for might be usefull.

I want to mount vnode-backed md(4) on boot without formatting it (e.g. for a
jail). Is it possible with current boot scripts?

I wrote a simple patch to mdmfs so such md disk can be put in /etc/fstab. It
adds '-K' option do mdmfs(8) to Keep contents. The line to attach such disk
in fstab looks like this:

md /jail mfs rw,-K,-F=/var/jailfile 0 0

Comments welcome. If people find it usefull I'd like to have it commited. I
can fill the PR with enhancement request.

Patch attached.

-- 
Michal Mertl

Index: mdmfs.8
===================================================================
RCS file: /home/fcvs/cvs/src/sbin/mdmfs/mdmfs.8,v
retrieving revision 1.20
diff -u -3 -r1.20 mdmfs.8
--- mdmfs.8 17 May 2004 08:35:41 -0000 1.20
+++ mdmfs.8 30 Nov 2004 10:56:22 -0000
@@ -36,7 +36,7 @@
 driver
 .Sh SYNOPSIS
 .Nm
-.Op Fl DLlMNSUX
+.Op Fl DKLlMNSUX
 .Op Fl a Ar maxcontig
 .Op Fl b Ar block-size
 .Op Fl c Ar cylinders
@@ -57,7 +57,7 @@
 .Ar mount-point
 .Nm
 .Fl C
-.Op Fl lNU
+.Op Fl KlNU
 .Op Fl a Ar maxcontig
 .Op Fl b Ar block-size
 .Op Fl c Ar cylinders
@@ -162,6 +162,12 @@
 The fragment size of the file system in bytes.
 .It Fl i Ar bytes
 Number of bytes per inode.
+.It Fl K
+Preserve contents of vnode-backed
+.Pq Dv MD_VNODE
+memory disk.
+Must be used in conjunction with
+.Fl F .
 .It Fl l
 Enable multilabel MAC on the new file system.
 .It Fl L
Index: mdmfs.c
===================================================================
RCS file: /home/fcvs/cvs/src/sbin/mdmfs/mdmfs.c,v
retrieving revision 1.20
diff -u -3 -r1.20 mdmfs.c
--- mdmfs.c 17 May 2004 07:07:20 -0000 1.20
+++ mdmfs.c 30 Nov 2004 10:51:56 -0000
@@ -89,7 +89,7 @@
             *mount_arg;
         enum md_types mdtype; /* The type of our memory disk. */
         bool have_mdtype;
- bool detach, softdep, autounit;
+ bool detach, softdep, autounit, keepdata;
         char *mtpoint, *unitstr;
         char *p;
         int ch;
@@ -119,7 +119,7 @@
                 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:KLlMm:Nn:O:o:p:Ss:t:Uv:w:X")) != -1)
                 switch (ch) {
                 case 'a':
                         argappend(&newfs_arg, "-a %s", optarg);
@@ -167,6 +167,8 @@
                                 usage();
                         loudsubs = true;
                         break;
+ case 'K':
+ keepdata = true;
                 case 'l':
                         argappend(&newfs_arg, "-l");
                         break;
@@ -233,7 +235,6 @@
         argv += optind;
         if (argc < 2)
                 usage();
-
         /* Make compatibility assumptions. */
         if (compat) {
                 mi.mi_mode = 01777;
@@ -258,6 +259,11 @@
         mtpoint = argv[1];
         if (!have_mdtype)
                 mdtype = MD_SWAP;
+
+ /* If we want to use vnode backed file and don't newfs it */
+ if (keepdata && mdtype != MD_VNODE)
+ err(1, "Must specify -F with -K");
+
         if (softdep)
                 argappend(&newfs_arg, "-U");
 
@@ -268,7 +274,8 @@
                 do_mdconfig_attach_au(mdconfig_arg, mdtype);
         else
                 do_mdconfig_attach(mdconfig_arg, mdtype);
- do_newfs(newfs_arg);
+ if (!keepdata)
+ do_newfs(newfs_arg);
         do_mount(mount_arg, mtpoint);
         do_mtptsetup(mtpoint, &mi);
 
@@ -665,13 +672,13 @@
                 name = "mdmfs";
         if (!compat)
                 fprintf(stderr,
-"usage: %s [-DLlMNSUX] [-a maxcontig [-b block-size] [-c cylinders]\n"
+"usage: %s [-DKLlMNSUX] [-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] [-w user:group]\n"
 "\tmd-device mount-point\n", name);
         fprintf(stderr,
-"usage: %s -C [-lNU] [-a maxcontig] [-b block-size] [-c cylinders]\n"
+"usage: %s -C [-lKNU] [-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] [-s size] md-device mount-point\n", name);

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• Previous message: Andrew Turner: "Live FreeBSD CD"
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