Split the root mount logic from the (generic) mount code and move

it (the root mount code) into a new file called vfs_mountroot.c

The split is almost trivial, as the code is almost perfectly
non-intertwined. The only adjustment needed was to move the UMA
zone allocation out of vfs_mountroot() [in vfs_mountroot.c] and
into vfs_mount.c, where it had to be done as a SYSINIT [see
vfs_mount_init()].

There are no functional changes with this commit.

1 files changed, 626 insertions, 0 deletions

diff --git a/sys/kern/vfs_mountroot.c b/sys/kern/vfs_mountroot.c
new file mode 100644
index 0000000..8685547
--- /dev/null
+++ b/sys/kern/vfs_mountroot.c
@@ -0,0 +1,626 @@
+/*-
+ * Copyright (c) 1999-2004 Poul-Henning Kamp
+ * Copyright (c) 1999 Michael Smith
+ * Copyright (c) 1989, 1993
+ *      The Regents of the University of California.  All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/conf.h>
+#include <sys/fcntl.h>
+#include <sys/jail.h>
+#include <sys/kernel.h>
+#include <sys/libkern.h>
+#include <sys/malloc.h>
+#include <sys/mount.h>
+#include <sys/mutex.h>
+#include <sys/namei.h>
+#include <sys/priv.h>
+#include <sys/proc.h>
+#include <sys/filedesc.h>
+#include <sys/reboot.h>
+#include <sys/syscallsubr.h>
+#include <sys/sysproto.h>
+#include <sys/sx.h>
+#include <sys/sysctl.h>
+#include <sys/sysent.h>
+#include <sys/systm.h>
+#include <sys/vnode.h>
+#include <vm/uma.h>
+
+#include <geom/geom.h>
+
+#include <machine/stdarg.h>
+
+#include "opt_rootdevname.h"
+
+#define	ROOTNAME		"root_device"
+
+static int	vfs_mountroot_ask(void);
+static int	vfs_mountroot_try(const char *mountfrom, const char *options);
+
+/*
+ * The vnode of the system's root (/ in the filesystem, without chroot
+ * active.)
+ */
+struct vnode	*rootvnode;
+
+/*
+ * The root filesystem is detailed in the kernel environment variable
+ * vfs.root.mountfrom, which is expected to be in the general format
+ *
+ * <vfsname>:[<path>][	<vfsname>:[<path>] ...]
+ * vfsname   := the name of a VFS known to the kernel and capable
+ *              of being mounted as root
+ * path      := disk device name or other data used by the filesystem
+ *              to locate its physical store
+ *
+ * If the environment variable vfs.root.mountfrom is a space separated list,
+ * each list element is tried in turn and the root filesystem will be mounted
+ * from the first one that suceeds.
+ *
+ * The environment variable vfs.root.mountfrom.options is a comma delimited
+ * set of string mount options.  These mount options must be parseable
+ * by nmount() in the kernel.
+ */
+
+/*
+ * The root specifiers we will try if RB_CDROM is specified.
+ */
+static char *cdrom_rootdevnames[] = {
+	"cd9660:cd0",
+	"cd9660:acd0",
+	NULL
+};
+
+/* legacy find-root code */
+char		*rootdevnames[2] = {NULL, NULL};
+#ifndef ROOTDEVNAME
+#  define ROOTDEVNAME NULL
+#endif
+static const char	*ctrootdevname = ROOTDEVNAME;
+
+struct root_hold_token {
+	const char			*who;
+	LIST_ENTRY(root_hold_token)	list;
+};
+
+static LIST_HEAD(, root_hold_token)	root_holds =
+    LIST_HEAD_INITIALIZER(root_holds);
+
+static int root_mount_complete;
+
+struct root_hold_token *
+root_mount_hold(const char *identifier)
+{
+	struct root_hold_token *h;
+
+	if (root_mounted())
+		return (NULL);
+
+	h = malloc(sizeof *h, M_DEVBUF, M_ZERO | M_WAITOK);
+	h->who = identifier;
+	mtx_lock(&mountlist_mtx);
+	LIST_INSERT_HEAD(&root_holds, h, list);
+	mtx_unlock(&mountlist_mtx);
+	return (h);
+}
+
+void
+root_mount_rel(struct root_hold_token *h)
+{
+
+	if (h == NULL)
+		return;
+	mtx_lock(&mountlist_mtx);
+	LIST_REMOVE(h, list);
+	wakeup(&root_holds);
+	mtx_unlock(&mountlist_mtx);
+	free(h, M_DEVBUF);
+}
+
+static void
+root_mount_prepare(void)
+{
+	struct root_hold_token *h;
+	struct timeval lastfail;
+	int curfail = 0;
+
+	for (;;) {
+		DROP_GIANT();
+		g_waitidle();
+		PICKUP_GIANT();
+		mtx_lock(&mountlist_mtx);
+		if (LIST_EMPTY(&root_holds)) {
+			mtx_unlock(&mountlist_mtx);
+			break;
+		}
+		if (ppsratecheck(&lastfail, &curfail, 1)) {
+			printf("Root mount waiting for:");
+			LIST_FOREACH(h, &root_holds, list)
+				printf(" %s", h->who);
+			printf("\n");
+		}
+		msleep(&root_holds, &mountlist_mtx, PZERO | PDROP, "roothold",
+		    hz);
+	}
+}
+
+static void
+root_mount_done(void)
+{
+
+	/* Keep prison0's root in sync with the global rootvnode. */
+	mtx_lock(&prison0.pr_mtx);
+	prison0.pr_root = rootvnode;
+	vref(prison0.pr_root);
+	mtx_unlock(&prison0.pr_mtx);
+	/*
+	 * Use a mutex to prevent the wakeup being missed and waiting for
+	 * an extra 1 second sleep.
+	 */
+	mtx_lock(&mountlist_mtx);
+	root_mount_complete = 1;
+	wakeup(&root_mount_complete);
+	mtx_unlock(&mountlist_mtx);
+}
+
+int
+root_mounted(void)
+{
+
+	/* No mutex is acquired here because int stores are atomic. */
+	return (root_mount_complete);
+}
+
+void
+root_mount_wait(void)
+{
+
+	/*
+	 * Panic on an obvious deadlock - the function can't be called from
+	 * a thread which is doing the whole SYSINIT stuff.
+	 */
+	KASSERT(curthread->td_proc->p_pid != 0,
+	    ("root_mount_wait: cannot be called from the swapper thread"));
+	mtx_lock(&mountlist_mtx);
+	while (!root_mount_complete) {
+		msleep(&root_mount_complete, &mountlist_mtx, PZERO, "rootwait",
+		    hz);
+	}
+	mtx_unlock(&mountlist_mtx);
+}
+
+static void
+set_rootvnode(void)
+{
+	struct proc *p;
+
+	if (VFS_ROOT(TAILQ_FIRST(&mountlist), LK_EXCLUSIVE, &rootvnode))
+		panic("Cannot find root vnode");
+
+	VOP_UNLOCK(rootvnode, 0);
+
+	p = curthread->td_proc;
+	FILEDESC_XLOCK(p->p_fd);
+
+	if (p->p_fd->fd_cdir != NULL)
+		vrele(p->p_fd->fd_cdir);
+	p->p_fd->fd_cdir = rootvnode;
+	VREF(rootvnode);
+
+	if (p->p_fd->fd_rdir != NULL)
+		vrele(p->p_fd->fd_rdir);
+	p->p_fd->fd_rdir = rootvnode;
+	VREF(rootvnode);
+
+	FILEDESC_XUNLOCK(p->p_fd);
+
+	EVENTHANDLER_INVOKE(mountroot);
+}
+
+static void
+devfs_first(void)
+{
+	struct thread *td = curthread;
+	struct vfsoptlist *opts;
+	struct vfsconf *vfsp;
+	struct mount *mp = NULL;
+	int error;
+
+	vfsp = vfs_byname("devfs");
+	KASSERT(vfsp != NULL, ("Could not find devfs by name"));
+	if (vfsp == NULL)
+		return;
+
+	mp = vfs_mount_alloc(NULLVP, vfsp, "/dev", td->td_ucred);
+
+	error = VFS_MOUNT(mp);
+	KASSERT(error == 0, ("VFS_MOUNT(devfs) failed %d", error));
+	if (error)
+		return;
+
+	opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK);
+	TAILQ_INIT(opts);
+	mp->mnt_opt = opts;
+
+	mtx_lock(&mountlist_mtx);
+	TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
+	mtx_unlock(&mountlist_mtx);
+
+	set_rootvnode();
+
+	error = kern_symlink(td, "/", "dev", UIO_SYSSPACE);
+	if (error)
+		printf("kern_symlink /dev -> / returns %d\n", error);
+}
+
+static void
+devfs_fixup(struct thread *td)
+{
+	struct nameidata nd;
+	struct vnode *vp, *dvp;
+	struct mount *mp;
+	int error;
+
+	/* Remove our devfs mount from the mountlist and purge the cache */
+	mtx_lock(&mountlist_mtx);
+	mp = TAILQ_FIRST(&mountlist);
+	TAILQ_REMOVE(&mountlist, mp, mnt_list);
+	mtx_unlock(&mountlist_mtx);
+	cache_purgevfs(mp);
+
+	VFS_ROOT(mp, LK_EXCLUSIVE, &dvp);
+	VI_LOCK(dvp);
+	dvp->v_iflag &= ~VI_MOUNT;
+	VI_UNLOCK(dvp);
+	dvp->v_mountedhere = NULL;
+
+	/* Set up the real rootvnode, and purge the cache */
+	TAILQ_FIRST(&mountlist)->mnt_vnodecovered = NULL;
+	set_rootvnode();
+	cache_purgevfs(rootvnode->v_mount);
+
+	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, "/dev", td);
+	error = namei(&nd);
+	if (error) {
+		printf("Lookup of /dev for devfs, error: %d\n", error);
+		vput(dvp);
+		vfs_unbusy(mp);
+		return;
+	}
+	NDFREE(&nd, NDF_ONLY_PNBUF);
+	vp = nd.ni_vp;
+	if (vp->v_type != VDIR) {
+		printf("/dev is not a directory\n");
+		vput(dvp);
+		vput(vp);
+		vfs_unbusy(mp);
+		return;
+	}
+	error = vinvalbuf(vp, V_SAVE, 0, 0);
+	if (error) {
+		printf("vinvalbuf() of /dev failed, error: %d\n", error);
+		vput(dvp);
+		vput(vp);
+		vfs_unbusy(mp);
+		return;
+	}
+	cache_purge(vp);
+	mp->mnt_vnodecovered = vp;
+	vp->v_mountedhere = mp;
+	mtx_lock(&mountlist_mtx);
+	TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
+	mtx_unlock(&mountlist_mtx);
+	VOP_UNLOCK(vp, 0);
+	vput(dvp);
+	vfs_unbusy(mp);
+
+	/* Unlink the no longer needed /dev/dev -> / symlink */
+	error = kern_unlink(td, "/dev/dev", UIO_SYSSPACE);
+	if (error)
+		printf("kern_unlink of /dev/dev failed, error: %d\n", error);
+}
+
+void
+vfs_mountroot(void)
+{
+	char *cp, *cpt, *options, *tmpdev;
+	int error, i, asked = 0;
+
+	options = NULL;
+
+	root_mount_prepare();
+
+	devfs_first();
+
+	/*
+	 * We are booted with instructions to prompt for the root filesystem.
+	 */
+	if (boothowto & RB_ASKNAME) {
+		if (!vfs_mountroot_ask())
+			goto mounted;
+		asked = 1;
+	}
+
+	options = getenv("vfs.root.mountfrom.options");
+
+	/*
+	 * The root filesystem information is compiled in, and we are
+	 * booted with instructions to use it.
+	 */
+	if (ctrootdevname != NULL && (boothowto & RB_DFLTROOT)) {
+		if (!vfs_mountroot_try(ctrootdevname, options))
+			goto mounted;
+		ctrootdevname = NULL;
+	}
+
+	/*
+	 * We've been given the generic "use CDROM as root" flag.  This is
+	 * necessary because one media may be used in many different
+	 * devices, so we need to search for them.
+	 */
+	if (boothowto & RB_CDROM) {
+		for (i = 0; cdrom_rootdevnames[i] != NULL; i++) {
+			if (!vfs_mountroot_try(cdrom_rootdevnames[i], options))
+				goto mounted;
+		}
+	}
+
+	/*
+	 * Try to use the value read by the loader from /etc/fstab, or
+	 * supplied via some other means.  This is the preferred
+	 * mechanism.
+	 */
+	cp = getenv("vfs.root.mountfrom");
+	if (cp != NULL) {
+		cpt = cp;
+		while ((tmpdev = strsep(&cpt, " \t")) != NULL) {
+			error = vfs_mountroot_try(tmpdev, options);
+			if (error == 0) {
+				freeenv(cp);
+				goto mounted;
+			}
+		}
+		freeenv(cp);
+	}
+
+	/*
+	 * Try values that may have been computed by code during boot
+	 */
+	if (!vfs_mountroot_try(rootdevnames[0], options))
+		goto mounted;
+	if (!vfs_mountroot_try(rootdevnames[1], options))
+		goto mounted;
+
+	/*
+	 * If we (still) have a compiled-in default, try it.
+	 */
+	if (ctrootdevname != NULL)
+		if (!vfs_mountroot_try(ctrootdevname, options))
+			goto mounted;
+	/*
+	 * Everything so far has failed, prompt on the console if we haven't
+	 * already tried that.
+	 */
+	if (!asked)
+		if (!vfs_mountroot_ask())
+			goto mounted;
+
+	panic("Root mount failed, startup aborted.");
+
+mounted:
+	root_mount_done();
+	freeenv(options);
+}
+
+static struct mntarg *
+parse_mountroot_options(struct mntarg *ma, const char *options)
+{
+	char *p;
+	char *name, *name_arg;
+	char *val, *val_arg;
+	char *opts;
+
+	if (options == NULL || options[0] == '\0')
+		return (ma);
+
+	p = opts = strdup(options, M_MOUNT);
+	if (opts == NULL) {
+		return (ma);
+	} 
+
+	while((name = strsep(&p, ",")) != NULL) {
+		if (name[0] == '\0')
+			break;
+
+		val = strchr(name, '=');
+		if (val != NULL) {
+			*val = '\0';
+			++val;
+		}
+		if( strcmp(name, "rw") == 0 ||
+		    strcmp(name, "noro") == 0) {
+			/*
+			 * The first time we mount the root file system,
+			 * we need to mount 'ro', so We need to ignore
+			 * 'rw' and 'noro' mount options.
+			 */
+			continue;
+		}
+		name_arg = strdup(name, M_MOUNT);
+		val_arg = NULL;
+		if (val != NULL) 
+			val_arg = strdup(val, M_MOUNT);
+
+		ma = mount_arg(ma, name_arg, val_arg,
+		    (val_arg != NULL ? -1 : 0));
+	}
+	free(opts, M_MOUNT);
+	return (ma);
+}
+
+/*
+ * Mount (mountfrom) as the root filesystem.
+ */
+static int
+vfs_mountroot_try(const char *mountfrom, const char *options)
+{
+	struct mount	*mp;
+	struct mntarg	*ma;
+	char		*vfsname, *path;
+	time_t		timebase;
+	int		error;
+	char		patt[32];
+	char		errmsg[255];
+
+	vfsname = NULL;
+	path    = NULL;
+	mp      = NULL;
+	ma	= NULL;
+	error   = EINVAL;
+	bzero(errmsg, sizeof(errmsg));
+
+	if (mountfrom == NULL)
+		return (error);		/* don't complain */
+	printf("Trying to mount root from %s\n", mountfrom);
+
+	/* parse vfs name and path */
+	vfsname = malloc(MFSNAMELEN, M_MOUNT, M_WAITOK);
+	path = malloc(MNAMELEN, M_MOUNT, M_WAITOK);
+	vfsname[0] = path[0] = 0;
+	sprintf(patt, "%%%d[a-z0-9]:%%%ds", MFSNAMELEN, MNAMELEN);
+	if (sscanf(mountfrom, patt, vfsname, path) < 1)
+		goto out;
+
+	if (path[0] == '\0')
+		strcpy(path, ROOTNAME);
+
+	ma = mount_arg(ma, "fstype", vfsname, -1);
+	ma = mount_arg(ma, "fspath", "/", -1);
+	ma = mount_arg(ma, "from", path, -1);
+	ma = mount_arg(ma, "errmsg", errmsg, sizeof(errmsg));
+	ma = mount_arg(ma, "ro", NULL, 0);
+	ma = parse_mountroot_options(ma, options);
+	error = kernel_mount(ma, MNT_ROOTFS);
+
+	if (error == 0) {
+		/*
+		 * We mount devfs prior to mounting the / FS, so the first
+		 * entry will typically be devfs.
+		 */
+		mp = TAILQ_FIRST(&mountlist);
+		KASSERT(mp != NULL, ("%s: mountlist is empty", __func__));
+
+		/*
+		 * Iterate over all currently mounted file systems and use
+		 * the time stamp found to check and/or initialize the RTC.
+		 * Typically devfs has no time stamp and the only other FS
+		 * is the actual / FS.
+		 * Call inittodr() only once and pass it the largest of the
+		 * timestamps we encounter.
+		 */
+		timebase = 0;
+		do {
+			if (mp->mnt_time > timebase)
+				timebase = mp->mnt_time;
+			mp = TAILQ_NEXT(mp, mnt_list);
+		} while (mp != NULL);
+		inittodr(timebase);
+
+		devfs_fixup(curthread);
+	}
+
+	if (error != 0 ) {
+		printf("ROOT MOUNT ERROR: %s\n", errmsg);
+		printf("If you have invalid mount options, reboot, and ");
+		printf("first try the following from\n");
+		printf("the loader prompt:\n\n");
+		printf("     set vfs.root.mountfrom.options=rw\n\n");
+		printf("and then remove invalid mount options from ");
+		printf("/etc/fstab.\n\n");
+	}
+out:
+	free(path, M_MOUNT);
+	free(vfsname, M_MOUNT);
+	return (error);
+}
+
+static int
+vfs_mountroot_ask(void)
+{
+	char name[128];
+	char *mountfrom;
+	char *options;
+
+	for(;;) {
+		printf("Loader variables:\n");
+		printf("vfs.root.mountfrom=");
+		mountfrom = getenv("vfs.root.mountfrom");
+		if (mountfrom != NULL) {
+			printf("%s", mountfrom);
+		}
+		printf("\n");
+		printf("vfs.root.mountfrom.options=");
+		options = getenv("vfs.root.mountfrom.options");
+		if (options != NULL) {
+			printf("%s", options);
+		}
+		printf("\n");
+		freeenv(mountfrom);
+		freeenv(options);
+		printf("\nManual root filesystem specification:\n");
+		printf("  <fstype>:<device>  Mount <device> using filesystem <fstype>\n");
+		printf("                       eg. zfs:tank\n");
+		printf("                       eg. ufs:/dev/da0s1a\n");
+		printf("                       eg. cd9660:/dev/acd0\n");
+		printf("                       This is equivalent to: ");
+		printf("mount -t cd9660 /dev/acd0 /\n"); 
+		printf("\n");
+		printf("  ?                  List valid disk boot devices\n");
+		printf("  <empty line>       Abort manual input\n");
+		printf("\nmountroot> ");
+		gets(name, sizeof(name), 1);
+		if (name[0] == '\0')
+			return (1);
+		if (name[0] == '?') {
+			printf("\nList of GEOM managed disk devices:\n  ");
+			g_dev_print();
+			continue;
+		}
+		if (!vfs_mountroot_try(name, NULL))
+			return (0);
+	}
+}