Date: Fri, 03 Dec 2004 22:22:56 +0100 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: arch@freebsd.org Subject: [HEADSUP] omount/nmount migration and rootfs mounting Message-ID: <26127.1102108976@critter.freebsd.dk>
next in thread | raw e-mail | index | archive | help
Ok, here is the big picture:
All filesystems get a ->vfs_mount() which does the job.
Filesystems which have a ->vfs_omount() looses it and gets
a ->vfs_cmount() instead which after pulling compat args in
calls the nmount() stuff.
Here is my prototype for ffs:
+static int
+ffs_cmount(char *path, void *data, int flags, struct thread *td)
+{
+ struct ufs_args args;
+ struct iovec v[10];
+ int error;
+
+ if (data == NULL)
+ return (EINVAL);
+ error = copyin(data, &args, sizeof args);
+ if (error)
+ return (error);
+
+ v[0].iov_base = "fstype";
+ v[0].iov_len = strlen(v[0].iov_base) + 1;
+ v[1].iov_base = "ufs";
+ v[1].iov_len = strlen(v[1].iov_base) + 1;
+
+ v[2].iov_base = "fspath";
+ v[2].iov_len = strlen(v[2].iov_base) + 1;
+ v[3].iov_base = path;
+ v[3].iov_len = strlen(v[3].iov_base) + 1;
+
+ v[4].iov_base = "from";
+ v[4].iov_len = strlen(v[4].iov_base) + 1;
+ v[5].iov_base = args.fspec;
+ v[5].iov_len = strlen(v[5].iov_base) + 1;
+
+ v[6].iov_base = "export";
+ v[6].iov_len = strlen(v[6].iov_base) + 1;
+ v[7].iov_base = &args.export;
+ v[7].iov_len = sizeof(args.export);
+
+ v[8].iov_base = NULL;
+ v[8].iov_len = 0;
+
+ error = kernel_mount(v, 8, flags);
+
+ return (error);
+}
Root mounting will happen the following way:
create a mountpoint.
devfs->vfs_mount() on it.
set rootdir for proc0
create symlink: /dev -> /
Mount real root filesystem as / using normal ->vfs_mount() method.
(filesystem contains no magic for this)
Surgically move the devfs mount from / to /dev in the new rootfs.
Keep an eye on p4:phk_bufwork, it works for ffs and nfs already.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?26127.1102108976>