The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_mountroot.c

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    1 /*-
    2  * Copyright (c) 2010 Marcel Moolenaar
    3  * Copyright (c) 1999-2004 Poul-Henning Kamp
    4  * Copyright (c) 1999 Michael Smith
    5  * Copyright (c) 1989, 1993
    6  *      The Regents of the University of California.  All rights reserved.
    7  * (c) UNIX System Laboratories, Inc.
    8  * All or some portions of this file are derived from material licensed
    9  * to the University of California by American Telephone and Telegraph
   10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   11  * the permission of UNIX System Laboratories, Inc.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  */
   37 
   38 #include "opt_rootdevname.h"
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: stable/10/sys/kern/vfs_mountroot.c 331276 2018-03-20 22:57:14Z ian $");
   42 
   43 #include <sys/param.h>
   44 #include <sys/conf.h>
   45 #include <sys/cons.h>
   46 #include <sys/fcntl.h>
   47 #include <sys/jail.h>
   48 #include <sys/kernel.h>
   49 #include <sys/malloc.h>
   50 #include <sys/mdioctl.h>
   51 #include <sys/mount.h>
   52 #include <sys/mutex.h>
   53 #include <sys/namei.h>
   54 #include <sys/priv.h>
   55 #include <sys/proc.h>
   56 #include <sys/filedesc.h>
   57 #include <sys/reboot.h>
   58 #include <sys/sbuf.h>
   59 #include <sys/stat.h>
   60 #include <sys/syscallsubr.h>
   61 #include <sys/sysproto.h>
   62 #include <sys/sx.h>
   63 #include <sys/sysctl.h>
   64 #include <sys/sysent.h>
   65 #include <sys/systm.h>
   66 #include <sys/vnode.h>
   67 
   68 #include <geom/geom.h>
   69 
   70 /*
   71  * The root filesystem is detailed in the kernel environment variable
   72  * vfs.root.mountfrom, which is expected to be in the general format
   73  *
   74  * <vfsname>:[<path>][  <vfsname>:[<path>] ...]
   75  * vfsname   := the name of a VFS known to the kernel and capable
   76  *              of being mounted as root
   77  * path      := disk device name or other data used by the filesystem
   78  *              to locate its physical store
   79  *
   80  * If the environment variable vfs.root.mountfrom is a space separated list,
   81  * each list element is tried in turn and the root filesystem will be mounted
   82  * from the first one that succeeds.
   83  *
   84  * The environment variable vfs.root.mountfrom.options is a comma delimited
   85  * set of string mount options.  These mount options must be parseable
   86  * by nmount() in the kernel.
   87  */
   88 
   89 static int parse_mount(char **);
   90 static struct mntarg *parse_mountroot_options(struct mntarg *, const char *);
   91 
   92 /*
   93  * The vnode of the system's root (/ in the filesystem, without chroot
   94  * active.)
   95  */
   96 struct vnode *rootvnode;
   97 
   98 /*
   99  * Mount of the system's /dev.
  100  */
  101 struct mount *rootdevmp;
  102 
  103 char *rootdevnames[2] = {NULL, NULL};
  104 
  105 struct mtx root_holds_mtx;
  106 MTX_SYSINIT(root_holds, &root_holds_mtx, "root_holds", MTX_DEF);
  107 
  108 struct root_hold_token {
  109         const char                      *who;
  110         LIST_ENTRY(root_hold_token)     list;
  111 };
  112 
  113 static LIST_HEAD(, root_hold_token)     root_holds =
  114     LIST_HEAD_INITIALIZER(root_holds);
  115 
  116 enum action {
  117         A_CONTINUE,
  118         A_PANIC,
  119         A_REBOOT,
  120         A_RETRY
  121 };
  122 
  123 static enum action root_mount_onfail = A_CONTINUE;
  124 
  125 static int root_mount_mddev;
  126 static int root_mount_complete;
  127 
  128 /* By default wait up to 3 seconds for devices to appear. */
  129 static int root_mount_timeout = 3;
  130 TUNABLE_INT("vfs.mountroot.timeout", &root_mount_timeout);
  131 
  132 struct root_hold_token *
  133 root_mount_hold(const char *identifier)
  134 {
  135         struct root_hold_token *h;
  136 
  137         if (root_mounted())
  138                 return (NULL);
  139 
  140         h = malloc(sizeof *h, M_DEVBUF, M_ZERO | M_WAITOK);
  141         h->who = identifier;
  142         mtx_lock(&root_holds_mtx);
  143         LIST_INSERT_HEAD(&root_holds, h, list);
  144         mtx_unlock(&root_holds_mtx);
  145         return (h);
  146 }
  147 
  148 void
  149 root_mount_rel(struct root_hold_token *h)
  150 {
  151 
  152         if (h == NULL)
  153                 return;
  154         mtx_lock(&root_holds_mtx);
  155         LIST_REMOVE(h, list);
  156         wakeup(&root_holds);
  157         mtx_unlock(&root_holds_mtx);
  158         free(h, M_DEVBUF);
  159 }
  160 
  161 int
  162 root_mounted(void)
  163 {
  164 
  165         /* No mutex is acquired here because int stores are atomic. */
  166         return (root_mount_complete);
  167 }
  168 
  169 void
  170 root_mount_wait(void)
  171 {
  172 
  173         /*
  174          * Panic on an obvious deadlock - the function can't be called from
  175          * a thread which is doing the whole SYSINIT stuff.
  176          */
  177         KASSERT(curthread->td_proc->p_pid != 0,
  178             ("root_mount_wait: cannot be called from the swapper thread"));
  179         mtx_lock(&root_holds_mtx);
  180         while (!root_mount_complete) {
  181                 msleep(&root_mount_complete, &root_holds_mtx, PZERO, "rootwait",
  182                     hz);
  183         }
  184         mtx_unlock(&root_holds_mtx);
  185 }
  186 
  187 static void
  188 set_rootvnode(void)
  189 {
  190         struct proc *p;
  191 
  192         if (VFS_ROOT(TAILQ_FIRST(&mountlist), LK_EXCLUSIVE, &rootvnode))
  193                 panic("Cannot find root vnode");
  194 
  195         VOP_UNLOCK(rootvnode, 0);
  196 
  197         p = curthread->td_proc;
  198         FILEDESC_XLOCK(p->p_fd);
  199 
  200         if (p->p_fd->fd_cdir != NULL)
  201                 vrele(p->p_fd->fd_cdir);
  202         p->p_fd->fd_cdir = rootvnode;
  203         VREF(rootvnode);
  204 
  205         if (p->p_fd->fd_rdir != NULL)
  206                 vrele(p->p_fd->fd_rdir);
  207         p->p_fd->fd_rdir = rootvnode;
  208         VREF(rootvnode);
  209 
  210         FILEDESC_XUNLOCK(p->p_fd);
  211 }
  212 
  213 static int
  214 vfs_mountroot_devfs(struct thread *td, struct mount **mpp)
  215 {
  216         struct vfsoptlist *opts;
  217         struct vfsconf *vfsp;
  218         struct mount *mp;
  219         int error;
  220 
  221         *mpp = NULL;
  222 
  223         if (rootdevmp != NULL) {
  224                 /*
  225                  * Already have /dev; this happens during rerooting.
  226                  */
  227                 error = vfs_busy(rootdevmp, 0);
  228                 if (error != 0)
  229                         return (error);
  230                 *mpp = rootdevmp;
  231         } else {
  232                 vfsp = vfs_byname("devfs");
  233                 KASSERT(vfsp != NULL, ("Could not find devfs by name"));
  234                 if (vfsp == NULL)
  235                         return (ENOENT);
  236 
  237                 mp = vfs_mount_alloc(NULLVP, vfsp, "/dev", td->td_ucred);
  238 
  239                 error = VFS_MOUNT(mp);
  240                 KASSERT(error == 0, ("VFS_MOUNT(devfs) failed %d", error));
  241                 if (error)
  242                         return (error);
  243 
  244                 opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK);
  245                 TAILQ_INIT(opts);
  246                 mp->mnt_opt = opts;
  247 
  248                 mtx_lock(&mountlist_mtx);
  249                 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
  250                 mtx_unlock(&mountlist_mtx);
  251 
  252                 *mpp = mp;
  253                 rootdevmp = mp;
  254         }
  255 
  256         set_rootvnode();
  257 
  258         error = kern_symlink(td, "/", "dev", UIO_SYSSPACE);
  259         if (error)
  260                 printf("kern_symlink /dev -> / returns %d\n", error);
  261 
  262         return (error);
  263 }
  264 
  265 static void
  266 vfs_mountroot_shuffle(struct thread *td, struct mount *mpdevfs)
  267 {
  268         struct nameidata nd;
  269         struct mount *mporoot, *mpnroot;
  270         struct vnode *vp, *vporoot, *vpdevfs;
  271         char *fspath;
  272         int error;
  273 
  274         mpnroot = TAILQ_NEXT(mpdevfs, mnt_list);
  275 
  276         /* Shuffle the mountlist. */
  277         mtx_lock(&mountlist_mtx);
  278         mporoot = TAILQ_FIRST(&mountlist);
  279         TAILQ_REMOVE(&mountlist, mpdevfs, mnt_list);
  280         if (mporoot != mpdevfs) {
  281                 TAILQ_REMOVE(&mountlist, mpnroot, mnt_list);
  282                 TAILQ_INSERT_HEAD(&mountlist, mpnroot, mnt_list);
  283         }
  284         TAILQ_INSERT_TAIL(&mountlist, mpdevfs, mnt_list);
  285         mtx_unlock(&mountlist_mtx);
  286 
  287         cache_purgevfs(mporoot);
  288         if (mporoot != mpdevfs)
  289                 cache_purgevfs(mpdevfs);
  290 
  291         VFS_ROOT(mporoot, LK_EXCLUSIVE, &vporoot);
  292 
  293         VI_LOCK(vporoot);
  294         vporoot->v_iflag &= ~VI_MOUNT;
  295         VI_UNLOCK(vporoot);
  296         vporoot->v_mountedhere = NULL;
  297         mporoot->mnt_flag &= ~MNT_ROOTFS;
  298         mporoot->mnt_vnodecovered = NULL;
  299         vput(vporoot);
  300 
  301         /* Set up the new rootvnode, and purge the cache */
  302         mpnroot->mnt_vnodecovered = NULL;
  303         set_rootvnode();
  304         cache_purgevfs(rootvnode->v_mount);
  305 
  306         if (mporoot != mpdevfs) {
  307                 /* Remount old root under /.mount or /mnt */
  308                 fspath = "/.mount";
  309                 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
  310                     fspath, td);
  311                 error = namei(&nd);
  312                 if (error) {
  313                         NDFREE(&nd, NDF_ONLY_PNBUF);
  314                         fspath = "/mnt";
  315                         NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
  316                             fspath, td);
  317                         error = namei(&nd);
  318                 }
  319                 if (!error) {
  320                         vp = nd.ni_vp;
  321                         error = (vp->v_type == VDIR) ? 0 : ENOTDIR;
  322                         if (!error)
  323                                 error = vinvalbuf(vp, V_SAVE, 0, 0);
  324                         if (!error) {
  325                                 cache_purge(vp);
  326                                 mporoot->mnt_vnodecovered = vp;
  327                                 vp->v_mountedhere = mporoot;
  328                                 strlcpy(mporoot->mnt_stat.f_mntonname,
  329                                     fspath, MNAMELEN);
  330                                 VOP_UNLOCK(vp, 0);
  331                         } else
  332                                 vput(vp);
  333                 }
  334                 NDFREE(&nd, NDF_ONLY_PNBUF);
  335 
  336                 if (error && bootverbose)
  337                         printf("mountroot: unable to remount previous root "
  338                             "under /.mount or /mnt (error %d).\n", error);
  339         }
  340 
  341         /* Remount devfs under /dev */
  342         NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, "/dev", td);
  343         error = namei(&nd);
  344         if (!error) {
  345                 vp = nd.ni_vp;
  346                 error = (vp->v_type == VDIR) ? 0 : ENOTDIR;
  347                 if (!error)
  348                         error = vinvalbuf(vp, V_SAVE, 0, 0);
  349                 if (!error) {
  350                         vpdevfs = mpdevfs->mnt_vnodecovered;
  351                         if (vpdevfs != NULL) {
  352                                 cache_purge(vpdevfs);
  353                                 vpdevfs->v_mountedhere = NULL;
  354                                 vrele(vpdevfs);
  355                         }
  356                         mpdevfs->mnt_vnodecovered = vp;
  357                         vp->v_mountedhere = mpdevfs;
  358                         VOP_UNLOCK(vp, 0);
  359                 } else
  360                         vput(vp);
  361         }
  362         if (error && bootverbose)
  363                 printf("mountroot: unable to remount devfs under /dev "
  364                     "(error %d).\n", error);
  365         NDFREE(&nd, NDF_ONLY_PNBUF);
  366 
  367         if (mporoot == mpdevfs) {
  368                 vfs_unbusy(mpdevfs);
  369                 /* Unlink the no longer needed /dev/dev -> / symlink */
  370                 error = kern_unlink(td, "/dev/dev", UIO_SYSSPACE);
  371                 if (error && bootverbose)
  372                         printf("mountroot: unable to unlink /dev/dev "
  373                             "(error %d)\n", error);
  374         }
  375 }
  376 
  377 /*
  378  * Configuration parser.
  379  */
  380 
  381 /* Parser character classes. */
  382 #define CC_WHITESPACE           -1
  383 #define CC_NONWHITESPACE        -2
  384 
  385 /* Parse errors. */
  386 #define PE_EOF                  -1
  387 #define PE_EOL                  -2
  388 
  389 static __inline int
  390 parse_peek(char **conf)
  391 {
  392 
  393         return (**conf);
  394 }
  395 
  396 static __inline void
  397 parse_poke(char **conf, int c)
  398 {
  399 
  400         **conf = c;
  401 }
  402 
  403 static __inline void
  404 parse_advance(char **conf)
  405 {
  406 
  407         (*conf)++;
  408 }
  409 
  410 static int
  411 parse_skipto(char **conf, int mc)
  412 {
  413         int c, match;
  414 
  415         while (1) {
  416                 c = parse_peek(conf);
  417                 if (c == 0)
  418                         return (PE_EOF);
  419                 switch (mc) {
  420                 case CC_WHITESPACE:
  421                         match = (c == ' ' || c == '\t' || c == '\n') ? 1 : 0;
  422                         break;
  423                 case CC_NONWHITESPACE:
  424                         if (c == '\n')
  425                                 return (PE_EOL);
  426                         match = (c != ' ' && c != '\t') ? 1 : 0;
  427                         break;
  428                 default:
  429                         match = (c == mc) ? 1 : 0;
  430                         break;
  431                 }
  432                 if (match)
  433                         break;
  434                 parse_advance(conf);
  435         }
  436         return (0);
  437 }
  438 
  439 static int
  440 parse_token(char **conf, char **tok)
  441 {
  442         char *p;
  443         size_t len;
  444         int error;
  445 
  446         *tok = NULL;
  447         error = parse_skipto(conf, CC_NONWHITESPACE);
  448         if (error)
  449                 return (error);
  450         p = *conf;
  451         error = parse_skipto(conf, CC_WHITESPACE);
  452         len = *conf - p;
  453         *tok = malloc(len + 1, M_TEMP, M_WAITOK | M_ZERO);
  454         bcopy(p, *tok, len);
  455         return (0);
  456 }
  457 
  458 static void
  459 parse_dir_ask_printenv(const char *var)
  460 {
  461         char *val;
  462 
  463         val = getenv(var);
  464         if (val != NULL) {
  465                 printf("  %s=%s\n", var, val);
  466                 freeenv(val);
  467         }
  468 }
  469 
  470 static int
  471 parse_dir_ask(char **conf)
  472 {
  473         char name[80];
  474         char *mnt;
  475         int error;
  476 
  477         printf("\nLoader variables:\n");
  478         parse_dir_ask_printenv("vfs.root.mountfrom");
  479         parse_dir_ask_printenv("vfs.root.mountfrom.options");
  480 
  481         printf("\nManual root filesystem specification:\n");
  482         printf("  <fstype>:<device> [options]\n");
  483         printf("      Mount <device> using filesystem <fstype>\n");
  484         printf("      and with the specified (optional) option list.\n");
  485         printf("\n");
  486         printf("    eg. ufs:/dev/da0s1a\n");
  487         printf("        zfs:tank\n");
  488         printf("        cd9660:/dev/acd0 ro\n");
  489         printf("          (which is equivalent to: ");
  490         printf("mount -t cd9660 -o ro /dev/acd0 /)\n");
  491         printf("\n");
  492         printf("  ?               List valid disk boot devices\n");
  493         printf("  .               Yield 1 second (for background tasks)\n");
  494         printf("  <empty line>    Abort manual input\n");
  495 
  496         do {
  497                 error = EINVAL;
  498                 printf("\nmountroot> ");
  499                 cngets(name, sizeof(name), GETS_ECHO);
  500                 if (name[0] == '\0')
  501                         break;
  502                 if (name[0] == '?' && name[1] == '\0') {
  503                         printf("\nList of GEOM managed disk devices:\n  ");
  504                         g_dev_print();
  505                         continue;
  506                 }
  507                 if (name[0] == '.' && name[1] == '\0') {
  508                         pause("rmask", hz);
  509                         continue;
  510                 }
  511                 mnt = name;
  512                 error = parse_mount(&mnt);
  513                 if (error == -1)
  514                         printf("Invalid file system specification.\n");
  515         } while (error != 0);
  516 
  517         return (error);
  518 }
  519 
  520 static int
  521 parse_dir_md(char **conf)
  522 {
  523         struct stat sb;
  524         struct thread *td;
  525         struct md_ioctl *mdio;
  526         char *path, *tok;
  527         int error, fd, len;
  528 
  529         td = curthread;
  530 
  531         error = parse_token(conf, &tok);
  532         if (error)
  533                 return (error);
  534 
  535         len = strlen(tok);
  536         mdio = malloc(sizeof(*mdio) + len + 1, M_TEMP, M_WAITOK | M_ZERO);
  537         path = (void *)(mdio + 1);
  538         bcopy(tok, path, len);
  539         free(tok, M_TEMP);
  540 
  541         /* Get file status. */
  542         error = kern_stat(td, path, UIO_SYSSPACE, &sb);
  543         if (error)
  544                 goto out;
  545 
  546         /* Open /dev/mdctl so that we can attach/detach. */
  547         error = kern_open(td, "/dev/" MDCTL_NAME, UIO_SYSSPACE, O_RDWR, 0);
  548         if (error)
  549                 goto out;
  550 
  551         fd = td->td_retval[0];
  552         mdio->md_version = MDIOVERSION;
  553         mdio->md_type = MD_VNODE;
  554 
  555         if (root_mount_mddev != -1) {
  556                 mdio->md_unit = root_mount_mddev;
  557                 DROP_GIANT();
  558                 error = kern_ioctl(td, fd, MDIOCDETACH, (void *)mdio);
  559                 PICKUP_GIANT();
  560                 /* Ignore errors. We don't care. */
  561                 root_mount_mddev = -1;
  562         }
  563 
  564         mdio->md_file = (void *)(mdio + 1);
  565         mdio->md_options = MD_AUTOUNIT | MD_READONLY;
  566         mdio->md_mediasize = sb.st_size;
  567         mdio->md_unit = 0;
  568         DROP_GIANT();
  569         error = kern_ioctl(td, fd, MDIOCATTACH, (void *)mdio);
  570         PICKUP_GIANT();
  571         if (error)
  572                 goto out;
  573 
  574         if (mdio->md_unit > 9) {
  575                 printf("rootmount: too many md units\n");
  576                 mdio->md_file = NULL;
  577                 mdio->md_options = 0;
  578                 mdio->md_mediasize = 0;
  579                 DROP_GIANT();
  580                 error = kern_ioctl(td, fd, MDIOCDETACH, (void *)mdio);
  581                 PICKUP_GIANT();
  582                 /* Ignore errors. We don't care. */
  583                 error = ERANGE;
  584                 goto out;
  585         }
  586 
  587         root_mount_mddev = mdio->md_unit;
  588         printf(MD_NAME "%u attached to %s\n", root_mount_mddev, mdio->md_file);
  589 
  590         error = kern_close(td, fd);
  591 
  592  out:
  593         free(mdio, M_TEMP);
  594         return (error);
  595 }
  596 
  597 static int
  598 parse_dir_onfail(char **conf)
  599 {
  600         char *action;
  601         int error;
  602 
  603         error = parse_token(conf, &action);
  604         if (error)
  605                 return (error);
  606 
  607         if (!strcmp(action, "continue"))
  608                 root_mount_onfail = A_CONTINUE;
  609         else if (!strcmp(action, "panic"))
  610                 root_mount_onfail = A_PANIC;
  611         else if (!strcmp(action, "reboot"))
  612                 root_mount_onfail = A_REBOOT;
  613         else if (!strcmp(action, "retry"))
  614                 root_mount_onfail = A_RETRY;
  615         else {
  616                 printf("rootmount: %s: unknown action\n", action);
  617                 error = EINVAL;
  618         }
  619 
  620         free(action, M_TEMP);
  621         return (0);
  622 }
  623 
  624 static int
  625 parse_dir_timeout(char **conf)
  626 {
  627         char *tok, *endtok;
  628         long secs;
  629         int error;
  630 
  631         error = parse_token(conf, &tok);
  632         if (error)
  633                 return (error);
  634 
  635         secs = strtol(tok, &endtok, 0);
  636         error = (secs < 0 || *endtok != '\0') ? EINVAL : 0;
  637         if (!error)
  638                 root_mount_timeout = secs;
  639         free(tok, M_TEMP);
  640         return (error);
  641 }
  642 
  643 static int
  644 parse_directive(char **conf)
  645 {
  646         char *dir;
  647         int error;
  648 
  649         error = parse_token(conf, &dir);
  650         if (error)
  651                 return (error);
  652 
  653         if (strcmp(dir, ".ask") == 0)
  654                 error = parse_dir_ask(conf);
  655         else if (strcmp(dir, ".md") == 0)
  656                 error = parse_dir_md(conf);
  657         else if (strcmp(dir, ".onfail") == 0)
  658                 error = parse_dir_onfail(conf);
  659         else if (strcmp(dir, ".timeout") == 0)
  660                 error = parse_dir_timeout(conf);
  661         else {
  662                 printf("mountroot: invalid directive `%s'\n", dir);
  663                 /* Ignore the rest of the line. */
  664                 (void)parse_skipto(conf, '\n');
  665                 error = EINVAL;
  666         }
  667         free(dir, M_TEMP);
  668         return (error);
  669 }
  670 
  671 static int
  672 parse_mount_dev_present(const char *dev)
  673 {
  674         struct nameidata nd;
  675         int error;
  676 
  677         NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, dev, curthread);
  678         error = namei(&nd);
  679         if (!error)
  680                 vput(nd.ni_vp);
  681         NDFREE(&nd, NDF_ONLY_PNBUF);
  682         return (error != 0) ? 0 : 1;
  683 }
  684 
  685 #define ERRMSGL 255
  686 static int
  687 parse_mount(char **conf)
  688 {
  689         char *errmsg;
  690         struct mntarg *ma;
  691         char *dev, *fs, *opts, *tok;
  692         int delay, error, timeout;
  693 
  694         error = parse_token(conf, &tok);
  695         if (error)
  696                 return (error);
  697         fs = tok;
  698         error = parse_skipto(&tok, ':');
  699         if (error) {
  700                 free(fs, M_TEMP);
  701                 return (error);
  702         }
  703         parse_poke(&tok, '\0');
  704         parse_advance(&tok);
  705         dev = tok;
  706 
  707         if (root_mount_mddev != -1) {
  708                 /* Handle substitution for the md unit number. */
  709                 tok = strstr(dev, "md#");
  710                 if (tok != NULL)
  711                         tok[2] = '' + root_mount_mddev;
  712         }
  713 
  714         /* Parse options. */
  715         error = parse_token(conf, &tok);
  716         opts = (error == 0) ? tok : NULL;
  717 
  718         printf("Trying to mount root from %s:%s [%s]...\n", fs, dev,
  719             (opts != NULL) ? opts : "");
  720 
  721         errmsg = malloc(ERRMSGL, M_TEMP, M_WAITOK | M_ZERO);
  722 
  723         if (vfs_byname(fs) == NULL) {
  724                 strlcpy(errmsg, "unknown file system", ERRMSGL);
  725                 error = ENOENT;
  726                 goto out;
  727         }
  728 
  729         if (strcmp(fs, "zfs") != 0 && strstr(fs, "nfs") == NULL && 
  730             dev[0] != '\0' && !parse_mount_dev_present(dev)) {
  731                 printf("mountroot: waiting for device %s ...\n", dev);
  732                 delay = hz / 10;
  733                 timeout = root_mount_timeout * hz;
  734                 do {
  735                         pause("rmdev", delay);
  736                         timeout -= delay;
  737                 } while (timeout > 0 && !parse_mount_dev_present(dev));
  738                 if (timeout <= 0) {
  739                         error = ENODEV;
  740                         goto out;
  741                 }
  742         }
  743 
  744         delay = hz / 10;
  745         timeout = root_mount_timeout * hz;
  746 
  747         for (;;) {
  748                 ma = NULL;
  749                 ma = mount_arg(ma, "fstype", fs, -1);
  750                 ma = mount_arg(ma, "fspath", "/", -1);
  751                 ma = mount_arg(ma, "from", dev, -1);
  752                 ma = mount_arg(ma, "errmsg", errmsg, ERRMSGL);
  753                 ma = mount_arg(ma, "ro", NULL, 0);
  754                 ma = parse_mountroot_options(ma, opts);
  755 
  756                 error = kernel_mount(ma, MNT_ROOTFS);
  757                 if (error == 0 || timeout <= 0)
  758                         break;
  759 
  760                 if (root_mount_timeout * hz == timeout ||
  761                     (bootverbose && timeout % hz == 0)) {
  762                         printf("Mounting from %s:%s failed with error %d; "
  763                             "retrying for %d more second%s\n", fs, dev, error,
  764                             timeout / hz, (timeout / hz > 1) ? "s" : "");
  765                 }
  766                 pause("rmretry", delay);
  767                 timeout -= delay;
  768         }
  769  out:
  770         if (error) {
  771                 printf("Mounting from %s:%s failed with error %d",
  772                     fs, dev, error);
  773                 if (errmsg[0] != '\0')
  774                         printf(": %s", errmsg);
  775                 printf(".\n");
  776         }
  777         free(fs, M_TEMP);
  778         free(errmsg, M_TEMP);
  779         if (opts != NULL)
  780                 free(opts, M_TEMP);
  781         /* kernel_mount can return -1 on error. */
  782         return ((error < 0) ? EDOOFUS : error);
  783 }
  784 #undef ERRMSGL
  785 
  786 static int
  787 vfs_mountroot_parse(struct sbuf *sb, struct mount *mpdevfs)
  788 {
  789         struct mount *mp;
  790         char *conf;
  791         int error;
  792 
  793         root_mount_mddev = -1;
  794 
  795 retry:
  796         conf = sbuf_data(sb);
  797         mp = TAILQ_NEXT(mpdevfs, mnt_list);
  798         error = (mp == NULL) ? 0 : EDOOFUS;
  799         root_mount_onfail = A_CONTINUE;
  800         while (mp == NULL) {
  801                 error = parse_skipto(&conf, CC_NONWHITESPACE);
  802                 if (error == PE_EOL) {
  803                         parse_advance(&conf);
  804                         continue;
  805                 }
  806                 if (error < 0)
  807                         break;
  808                 switch (parse_peek(&conf)) {
  809                 case '#':
  810                         error = parse_skipto(&conf, '\n');
  811                         break;
  812                 case '.':
  813                         error = parse_directive(&conf);
  814                         break;
  815                 default:
  816                         error = parse_mount(&conf);
  817                         break;
  818                 }
  819                 if (error < 0)
  820                         break;
  821                 /* Ignore any trailing garbage on the line. */
  822                 if (parse_peek(&conf) != '\n') {
  823                         printf("mountroot: advancing to next directive...\n");
  824                         (void)parse_skipto(&conf, '\n');
  825                 }
  826                 mp = TAILQ_NEXT(mpdevfs, mnt_list);
  827         }
  828         if (mp != NULL)
  829                 return (0);
  830 
  831         /*
  832          * We failed to mount (a new) root.
  833          */
  834         switch (root_mount_onfail) {
  835         case A_CONTINUE:
  836                 break;
  837         case A_PANIC:
  838                 panic("mountroot: unable to (re-)mount root.");
  839                 /* NOTREACHED */
  840         case A_RETRY:
  841                 goto retry;
  842         case A_REBOOT:
  843                 kern_reboot(RB_NOSYNC);
  844                 /* NOTREACHED */
  845         }
  846 
  847         return (error);
  848 }
  849 
  850 static void
  851 vfs_mountroot_conf0(struct sbuf *sb)
  852 {
  853         char *s, *tok, *mnt, *opt;
  854         int error;
  855 
  856         sbuf_printf(sb, ".onfail panic\n");
  857         sbuf_printf(sb, ".timeout %d\n", root_mount_timeout);
  858         if (boothowto & RB_ASKNAME)
  859                 sbuf_printf(sb, ".ask\n");
  860 #ifdef ROOTDEVNAME
  861         if (boothowto & RB_DFLTROOT)
  862                 sbuf_printf(sb, "%s\n", ROOTDEVNAME);
  863 #endif
  864         if (boothowto & RB_CDROM) {
  865                 sbuf_printf(sb, "cd9660:/dev/cd0 ro\n");
  866                 sbuf_printf(sb, ".timeout 0\n");
  867                 sbuf_printf(sb, "cd9660:/dev/acd0 ro\n");
  868                 sbuf_printf(sb, ".timeout %d\n", root_mount_timeout);
  869         }
  870         s = getenv("vfs.root.mountfrom");
  871         if (s != NULL) {
  872                 opt = getenv("vfs.root.mountfrom.options");
  873                 tok = s;
  874                 error = parse_token(&tok, &mnt);
  875                 while (!error) {
  876                         sbuf_printf(sb, "%s %s\n", mnt,
  877                             (opt != NULL) ? opt : "");
  878                         free(mnt, M_TEMP);
  879                         error = parse_token(&tok, &mnt);
  880                 }
  881                 if (opt != NULL)
  882                         freeenv(opt);
  883                 freeenv(s);
  884         }
  885         if (rootdevnames[0] != NULL)
  886                 sbuf_printf(sb, "%s\n", rootdevnames[0]);
  887         if (rootdevnames[1] != NULL)
  888                 sbuf_printf(sb, "%s\n", rootdevnames[1]);
  889 #ifdef ROOTDEVNAME
  890         if (!(boothowto & RB_DFLTROOT))
  891                 sbuf_printf(sb, "%s\n", ROOTDEVNAME);
  892 #endif
  893         if (!(boothowto & RB_ASKNAME))
  894                 sbuf_printf(sb, ".ask\n");
  895 }
  896 
  897 static int
  898 vfs_mountroot_readconf(struct thread *td, struct sbuf *sb)
  899 {
  900         static char buf[128];
  901         struct nameidata nd;
  902         off_t ofs;
  903         ssize_t resid;
  904         int error, flags, len;
  905 
  906         NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, "/.mount.conf", td);
  907         flags = FREAD;
  908         error = vn_open(&nd, &flags, 0, NULL);
  909         if (error)
  910                 return (error);
  911 
  912         NDFREE(&nd, NDF_ONLY_PNBUF);
  913         ofs = 0;
  914         len = sizeof(buf) - 1;
  915         while (1) {
  916                 error = vn_rdwr(UIO_READ, nd.ni_vp, buf, len, ofs,
  917                     UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
  918                     NOCRED, &resid, td);
  919                 if (error)
  920                         break;
  921                 if (resid == len)
  922                         break;
  923                 buf[len - resid] = 0;
  924                 sbuf_printf(sb, "%s", buf);
  925                 ofs += len - resid;
  926         }
  927 
  928         VOP_UNLOCK(nd.ni_vp, 0);
  929         vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
  930         return (error);
  931 }
  932 
  933 static void
  934 vfs_mountroot_wait(void)
  935 {
  936         struct root_hold_token *h;
  937         struct timeval lastfail;
  938         int curfail;
  939 
  940         curfail = 0;
  941         while (1) {
  942                 DROP_GIANT();
  943                 g_waitidle();
  944                 PICKUP_GIANT();
  945                 mtx_lock(&root_holds_mtx);
  946                 if (LIST_EMPTY(&root_holds)) {
  947                         mtx_unlock(&root_holds_mtx);
  948                         break;
  949                 }
  950                 if (ppsratecheck(&lastfail, &curfail, 1)) {
  951                         printf("Root mount waiting for:");
  952                         LIST_FOREACH(h, &root_holds, list)
  953                                 printf(" %s", h->who);
  954                         printf("\n");
  955                 }
  956                 msleep(&root_holds, &root_holds_mtx, PZERO | PDROP, "roothold",
  957                     hz);
  958         }
  959 }
  960 
  961 void
  962 vfs_mountroot(void)
  963 {
  964         struct mount *mp;
  965         struct sbuf *sb;
  966         struct thread *td;
  967         time_t timebase;
  968         int error;
  969 
  970         td = curthread;
  971 
  972         vfs_mountroot_wait();
  973 
  974         sb = sbuf_new_auto();
  975         vfs_mountroot_conf0(sb);
  976         sbuf_finish(sb);
  977 
  978         error = vfs_mountroot_devfs(td, &mp);
  979         while (!error) {
  980                 error = vfs_mountroot_parse(sb, mp);
  981                 if (!error) {
  982                         vfs_mountroot_shuffle(td, mp);
  983                         sbuf_clear(sb);
  984                         error = vfs_mountroot_readconf(td, sb);
  985                         sbuf_finish(sb);
  986                 }
  987         }
  988 
  989         sbuf_delete(sb);
  990 
  991         /*
  992          * Iterate over all currently mounted file systems and use
  993          * the time stamp found to check and/or initialize the RTC.
  994          * Call inittodr() only once and pass it the largest of the
  995          * timestamps we encounter.
  996          */
  997         timebase = 0;
  998         mtx_lock(&mountlist_mtx);
  999         mp = TAILQ_FIRST(&mountlist);
 1000         while (mp != NULL) {
 1001                 if (mp->mnt_time > timebase)
 1002                         timebase = mp->mnt_time;
 1003                 mp = TAILQ_NEXT(mp, mnt_list);
 1004         }
 1005         mtx_unlock(&mountlist_mtx);
 1006         inittodr(timebase);
 1007 
 1008         /* Keep prison0's root in sync with the global rootvnode. */
 1009         mtx_lock(&prison0.pr_mtx);
 1010         prison0.pr_root = rootvnode;
 1011         vref(prison0.pr_root);
 1012         mtx_unlock(&prison0.pr_mtx);
 1013 
 1014         mtx_lock(&root_holds_mtx);
 1015         atomic_store_rel_int(&root_mount_complete, 1);
 1016         wakeup(&root_mount_complete);
 1017         mtx_unlock(&root_holds_mtx);
 1018 
 1019         EVENTHANDLER_INVOKE(mountroot);
 1020 }
 1021 
 1022 static struct mntarg *
 1023 parse_mountroot_options(struct mntarg *ma, const char *options)
 1024 {
 1025         char *p;
 1026         char *name, *name_arg;
 1027         char *val, *val_arg;
 1028         char *opts;
 1029 
 1030         if (options == NULL || options[0] == '\0')
 1031                 return (ma);
 1032 
 1033         p = opts = strdup(options, M_MOUNT);
 1034         if (opts == NULL) {
 1035                 return (ma);
 1036         }
 1037 
 1038         while((name = strsep(&p, ",")) != NULL) {
 1039                 if (name[0] == '\0')
 1040                         break;
 1041 
 1042                 val = strchr(name, '=');
 1043                 if (val != NULL) {
 1044                         *val = '\0';
 1045                         ++val;
 1046                 }
 1047                 if( strcmp(name, "rw") == 0 ||
 1048                     strcmp(name, "noro") == 0) {
 1049                         /*
 1050                          * The first time we mount the root file system,
 1051                          * we need to mount 'ro', so We need to ignore
 1052                          * 'rw' and 'noro' mount options.
 1053                          */
 1054                         continue;
 1055                 }
 1056                 name_arg = strdup(name, M_MOUNT);
 1057                 val_arg = NULL;
 1058                 if (val != NULL)
 1059                         val_arg = strdup(val, M_MOUNT);
 1060 
 1061                 ma = mount_arg(ma, name_arg, val_arg,
 1062                     (val_arg != NULL ? -1 : 0));
 1063         }
 1064         free(opts, M_MOUNT);
 1065         return (ma);
 1066 }

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