devfs_devs.c

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    1 #define DEBUG 1
    2 /*
    3  * Copyright (c) 2000
    4  *      Poul-Henning Kamp.  All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Neither the name of the University nor the names of its contributors
   12  *    may be used to endorse or promote products derived from this software
   13  *    without specific prior written permission.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  *
   27  * From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vfsops.c 1.36
   28  *
   29  * $FreeBSD: releng/5.0/sys/fs/devfs/devfs_devs.c 107698 2002-12-09 03:44:28Z rwatson $
   30  */
   31 
   32 #include "opt_devfs.h"
   33 #include "opt_mac.h"
   34 #ifndef NODEVFS
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/conf.h>
   39 #include <sys/dirent.h>
   40 #include <sys/kernel.h>
   41 #include <sys/lock.h>
   42 #include <sys/mac.h>
   43 #include <sys/malloc.h>
   44 #include <sys/proc.h>
   45 #include <sys/sysctl.h>
   46 #include <sys/vnode.h>
   47 
   48 #include <machine/atomic.h>
   49 
   50 #include <fs/devfs/devfs.h>
   51 
   52 static dev_t devfs_inot[NDEVFSINO];
   53 static dev_t *devfs_overflow;
   54 static int devfs_ref[NDEVFSINO];
   55 static int *devfs_refoverflow;
   56 static int devfs_nextino = 3;
   57 static int devfs_numino;
   58 static int devfs_topino;
   59 static int devfs_noverflowwant = NDEVFSOVERFLOW;
   60 static int devfs_noverflow;
   61 static unsigned devfs_generation;
   62 
   63 static void devfs_attemptoverflow(int insist);
   64 static struct devfs_dirent *devfs_find (struct devfs_dirent *dd, const char *name, int namelen);
   65 
   66 SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");
   67 SYSCTL_UINT(_vfs_devfs, OID_AUTO, noverflow, CTLFLAG_RW,
   68         &devfs_noverflowwant, 0, "Size of DEVFS overflow table");
   69 SYSCTL_UINT(_vfs_devfs, OID_AUTO, generation, CTLFLAG_RD,
   70         &devfs_generation, 0, "DEVFS generation number");
   71 SYSCTL_UINT(_vfs_devfs, OID_AUTO, inodes, CTLFLAG_RD,
   72         &devfs_numino, 0, "DEVFS inodes");
   73 SYSCTL_UINT(_vfs_devfs, OID_AUTO, topinode, CTLFLAG_RD,
   74         &devfs_topino, 0, "DEVFS highest inode#");
   75 
   76 static int *
   77 devfs_itor(int inode)
   78 {
   79         if (inode < NDEVFSINO)
   80                 return (&devfs_ref[inode]);
   81         else if (inode < NDEVFSINO + devfs_noverflow)
   82                 return (&devfs_refoverflow[inode - NDEVFSINO]);
   83         else
   84                 panic ("YRK!");
   85 }
   86 
   87 static void
   88 devfs_dropref(int inode)
   89 {
   90         int *ip;
   91 
   92         ip = devfs_itor(inode);
   93         atomic_add_int(ip, -1);
   94 }
   95 
   96 static int
   97 devfs_getref(int inode)
   98 {
   99         int *ip, i, j;
  100         dev_t *dp;
  101 
  102         ip = devfs_itor(inode);
  103         dp = devfs_itod(inode);
  104         for (;;) {
  105                 i = *ip;
  106                 j = i + 1;
  107                 if (!atomic_cmpset_int(ip, i, j))
  108                         continue;
  109                 if (*dp != NULL)
  110                         return (1);
  111                 atomic_add_int(ip, -1);
  112                 return(0);
  113         }
  114 }
  115 
  116 struct devfs_dirent **
  117 devfs_itode (struct devfs_mount *dm, int inode)
  118 {
  119 
  120         if (inode < NDEVFSINO)
  121                 return (&dm->dm_dirent[inode]);
  122         if (devfs_overflow == NULL)
  123                 return (NULL);
  124         if (inode < NDEVFSINO + devfs_noverflow)
  125                 return (&dm->dm_overflow[inode - NDEVFSINO]);
  126         return (NULL);
  127 }
  128 
  129 dev_t *
  130 devfs_itod (int inode)
  131 {
  132 
  133         if (inode < NDEVFSINO)
  134                 return (&devfs_inot[inode]);
  135         if (devfs_overflow == NULL)
  136                 return (NULL);
  137         if (inode < NDEVFSINO + devfs_noverflow)
  138                 return (&devfs_overflow[inode - NDEVFSINO]);
  139         return (NULL);
  140 }
  141 
  142 static void
  143 devfs_attemptoverflow(int insist)
  144 {
  145         dev_t **ot;
  146         int *or;
  147         int n, nb;
  148 
  149         /* Check if somebody beat us to it */
  150         if (devfs_overflow != NULL)
  151                 return;
  152         ot = NULL;
  153         or = NULL;
  154         n = devfs_noverflowwant;
  155         nb = sizeof (dev_t *) * n;
  156         MALLOC(ot, dev_t **, nb, M_DEVFS, (insist ? M_WAITOK : M_NOWAIT) | M_ZERO);
  157         if (ot == NULL)
  158                 goto bail;
  159         nb = sizeof (int) * n;
  160         MALLOC(or, int *, nb, M_DEVFS, (insist ? M_WAITOK : M_NOWAIT) | M_ZERO);
  161         if (or == NULL)
  162                 goto bail;
  163         if (!atomic_cmpset_ptr(&devfs_overflow, NULL, ot))
  164                 goto bail;
  165         devfs_refoverflow = or;
  166         devfs_noverflow = n;
  167         printf("DEVFS Overflow table with %d entries allocated when %d in use\n", n, devfs_numino);
  168         return;
  169 
  170 bail:
  171         /* Somebody beat us to it, or something went wrong. */
  172         if (ot != NULL)
  173                 FREE(ot, M_DEVFS);
  174         if (or != NULL)
  175                 FREE(or, M_DEVFS);
  176         return;
  177 }
  178 
  179 static struct devfs_dirent *
  180 devfs_find(struct devfs_dirent *dd, const char *name, int namelen)
  181 {
  182         struct devfs_dirent *de;
  183 
  184         TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
  185                 if (namelen != de->de_dirent->d_namlen)
  186                         continue;
  187                 if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
  188                         continue;
  189                 break;
  190         }
  191         return (de);
  192 }
  193 
  194 struct devfs_dirent *
  195 devfs_newdirent(char *name, int namelen)
  196 {
  197         int i;
  198         struct devfs_dirent *de;
  199         struct dirent d;
  200 
  201         d.d_namlen = namelen;
  202         i = sizeof (*de) + GENERIC_DIRSIZ(&d);
  203         MALLOC(de, struct devfs_dirent *, i, M_DEVFS, M_WAITOK | M_ZERO);
  204         de->de_dirent = (struct dirent *)(de + 1);
  205         de->de_dirent->d_namlen = namelen;
  206         de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
  207         bcopy(name, de->de_dirent->d_name, namelen);
  208         de->de_dirent->d_name[namelen] = '\0';
  209         vfs_timestamp(&de->de_ctime);
  210         de->de_mtime = de->de_atime = de->de_ctime;
  211         de->de_links = 1;
  212 #ifdef MAC
  213         mac_init_devfsdirent(de);
  214 #endif
  215         return (de);
  216 }
  217 
  218 struct devfs_dirent *
  219 devfs_vmkdir(char *name, int namelen, struct devfs_dirent *dotdot)
  220 {
  221         struct devfs_dirent *dd;
  222         struct devfs_dirent *de;
  223 
  224         dd = devfs_newdirent(name, namelen);
  225 
  226         TAILQ_INIT(&dd->de_dlist);
  227 
  228         dd->de_dirent->d_type = DT_DIR;
  229         dd->de_mode = 0555;
  230         dd->de_links = 2;
  231         dd->de_dir = dd;
  232 
  233         de = devfs_newdirent(".", 1);
  234         de->de_dirent->d_type = DT_DIR;
  235         de->de_dir = dd;
  236         de->de_flags |= DE_DOT;
  237         TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
  238 
  239         de = devfs_newdirent("..", 2);
  240         de->de_dirent->d_type = DT_DIR;
  241         if (dotdot == NULL)
  242                 de->de_dir = dd;
  243         else
  244                 de->de_dir = dotdot;
  245         de->de_flags |= DE_DOTDOT;
  246         TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
  247 
  248         return (dd);
  249 }
  250 
  251 static void
  252 devfs_delete(struct devfs_dirent *dd, struct devfs_dirent *de)
  253 {
  254 
  255         if (de->de_symlink) {
  256                 FREE(de->de_symlink, M_DEVFS);
  257                 de->de_symlink = NULL;
  258         }
  259         if (de->de_vnode)
  260                 de->de_vnode->v_data = NULL;
  261         TAILQ_REMOVE(&dd->de_dlist, de, de_list);
  262 #ifdef MAC
  263         mac_destroy_devfsdirent(de);
  264 #endif
  265         FREE(de, M_DEVFS);
  266 }
  267 
  268 void
  269 devfs_purge(struct devfs_dirent *dd)
  270 {
  271         struct devfs_dirent *de;
  272 
  273         for (;;) {
  274                 de = TAILQ_FIRST(&dd->de_dlist);
  275                 if (de == NULL)
  276                         break;
  277                 devfs_delete(dd, de);
  278         }
  279         FREE(dd, M_DEVFS);
  280 }
  281 
  282 
  283 int
  284 devfs_populate(struct devfs_mount *dm)
  285 {
  286         int i, j;
  287         dev_t dev, pdev;
  288         struct devfs_dirent *dd;
  289         struct devfs_dirent *de, **dep;
  290         char *q, *s;
  291 
  292         if (dm->dm_generation == devfs_generation)
  293                 return (0);
  294         lockmgr(&dm->dm_lock, LK_UPGRADE, 0, curthread);
  295         if (devfs_noverflow && dm->dm_overflow == NULL) {
  296                 i = devfs_noverflow * sizeof (struct devfs_dirent *);
  297                 MALLOC(dm->dm_overflow, struct devfs_dirent **, i,
  298                         M_DEVFS, M_WAITOK | M_ZERO);
  299         }
  300         while (dm->dm_generation != devfs_generation) {
  301                 dm->dm_generation = devfs_generation;
  302                 for (i = 0; i <= devfs_topino; i++) {
  303                         dev = *devfs_itod(i);
  304                         dep = devfs_itode(dm, i);
  305                         de = *dep;
  306                         if (dev == NULL && de == DE_DELETED) {
  307                                 *dep = NULL;
  308                                 continue;
  309                         }
  310                         if (dev == NULL && de != NULL) {
  311                                 dd = de->de_dir;
  312                                 *dep = NULL;
  313                                 TAILQ_REMOVE(&dd->de_dlist, de, de_list);
  314                                 if (de->de_vnode)
  315                                         de->de_vnode->v_data = NULL;
  316                                 FREE(de, M_DEVFS);
  317                                 devfs_dropref(i);
  318                                 continue;
  319                         }
  320                         if (dev == NULL)
  321                                 continue;
  322                         if (de != NULL)
  323                                 continue;
  324                         if (!devfs_getref(i))
  325                                 continue;
  326                         dd = dm->dm_basedir;
  327                         s = dev->si_name;
  328                         for (;;) {
  329                                 for (q = s; *q != '/' && *q != '\0'; q++)
  330                                         continue;
  331                                 if (*q != '/')
  332                                         break;
  333                                 de = devfs_find(dd, s, q - s);
  334                                 if (de == NULL) {
  335                                         de = devfs_vmkdir(s, q - s, dd);
  336 #ifdef MAC
  337                                         mac_create_devfs_directory(
  338                                             dm->dm_mount, s, q - s, de);
  339 #endif
  340                                         de->de_inode = dm->dm_inode++;
  341                                         TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
  342                                         dd->de_links++;
  343                                 }
  344                                 s = q + 1;
  345                                 dd = de;
  346                         }
  347                         de = devfs_newdirent(s, q - s);
  348                         if (dev->si_flags & SI_ALIAS) {
  349                                 de->de_inode = dm->dm_inode++;
  350                                 de->de_uid = 0;
  351                                 de->de_gid = 0;
  352                                 de->de_mode = 0755;
  353                                 de->de_dirent->d_type = DT_LNK;
  354                                 pdev = dev->si_parent;
  355                                 j = strlen(pdev->si_name) + 1;
  356                                 MALLOC(de->de_symlink, char *, j, M_DEVFS, M_WAITOK);
  357                                 bcopy(pdev->si_name, de->de_symlink, j);
  358                         } else {
  359                                 de->de_inode = i;
  360                                 de->de_uid = dev->si_uid;
  361                                 de->de_gid = dev->si_gid;
  362                                 de->de_mode = dev->si_mode;
  363                                 de->de_dirent->d_type = DT_CHR;
  364                         }
  365 #ifdef MAC
  366                         mac_create_devfs_device(dm->dm_mount, dev, de);
  367 #endif
  368                         *dep = de;
  369                         de->de_dir = dd;
  370                         devfs_rules_apply(dm, de);
  371                         TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
  372 #if 0
  373                         printf("Add ino%d %s\n", i, dev->si_name);
  374 #endif
  375                 }
  376         }
  377         lockmgr(&dm->dm_lock, LK_DOWNGRADE, 0, curthread);
  378         return (0);
  379 }
  380 
  381 static void
  382 devfs_create(dev_t dev)
  383 {
  384         int ino, i, *ip;
  385         dev_t *dp;
  386 
  387         for (;;) {
  388                 /* Grab the next inode number */
  389                 ino = devfs_nextino;
  390                 i = ino + 1;
  391                 /* wrap around when we reach the end */
  392                 if (i >= NDEVFSINO + devfs_noverflow)
  393                         i = 3;
  394                 if (!atomic_cmpset_int(&devfs_nextino, ino, i))
  395                         continue;
  396 
  397                 /* see if it was occupied */
  398                 dp = devfs_itod(ino);
  399                 if (dp == NULL)
  400                         Debugger("dp == NULL\n");
  401                 if (*dp != NULL)
  402                         continue;
  403                 ip = devfs_itor(ino);
  404                 if (ip == NULL)
  405                         Debugger("ip == NULL\n");
  406                 if (*ip != 0)
  407                         continue;
  408 
  409                 if (!atomic_cmpset_ptr(dp, NULL, dev))
  410                         continue;
  411 
  412                 dev->si_inode = ino;
  413                 for (;;) {
  414                         i = devfs_topino;
  415                         if (i >= ino)
  416                                 break;
  417                         if (atomic_cmpset_int(&devfs_topino, i, ino))
  418                                 break;
  419                         printf("failed topino %d %d\n", i, ino);
  420                 }
  421                 break;
  422         }
  423 
  424         atomic_add_int(&devfs_numino, 1);
  425         atomic_add_int(&devfs_generation, 1);
  426         if (devfs_overflow == NULL && devfs_numino + 100 > NDEVFSINO)
  427                 devfs_attemptoverflow(0);
  428 }
  429 
  430 static void
  431 devfs_destroy(dev_t dev)
  432 {
  433         int ino, i;
  434 
  435         ino = dev->si_inode;
  436         dev->si_inode = 0;
  437         if (ino == 0)
  438                 return;
  439         if (atomic_cmpset_ptr(devfs_itod(ino), dev, NULL)) {
  440                 atomic_add_int(&devfs_generation, 1);
  441                 atomic_add_int(&devfs_numino, -1);
  442                 i = devfs_nextino;
  443                 if (ino < i)
  444                         atomic_cmpset_int(&devfs_nextino, i, ino);
  445         }
  446 }
  447 
  448 static void
  449 devfs_init(void *junk)
  450 {
  451         devfs_create_hook = devfs_create;
  452         devfs_destroy_hook = devfs_destroy;
  453         devfs_present = 1;
  454         devfs_rules_init();
  455 }
  456 
  457 SYSINIT(devfs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_init, NULL);
  458 
  459 #endif
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FreeBSD/Linux Kernel Cross Reference sys/fs/devfs/devfs_devs.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/devfs/devfs_devs.c
