sys/miscfs/nullfs/null_vfsops.c

   1 /*      $NetBSD: null_vfsops.c,v 1.78 2008/12/05 13:05:37 ad Exp $      */
   2
   3 /*
   4  * Copyright (c) 1999 National Aeronautics & Space Administration
   5  * All rights reserved.
   6  *
   7  * This software was written by William Studenmund of the
   8  * Numerical Aerospace Simulation Facility, NASA Ames Research Center.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the National Aeronautics & Space Administration
  19  *    nor the names of its contributors may be used to endorse or promote
  20  *    products derived from this software without specific prior written
  21  *    permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
  24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  25  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  26  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB-
  27  * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  28  * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33  * POSSIBILITY OF SUCH DAMAGE.
  34  */
  35 /*
  36  * Copyright (c) 1992, 1993, 1995
  37  *      The Regents of the University of California.  All rights reserved.
  38  *
  39  * This code is derived from software donated to Berkeley by
  40  * Jan-Simon Pendry.
  41  *
  42  * Redistribution and use in source and binary forms, with or without
  43  * modification, are permitted provided that the following conditions
  44  * are met:
  45  * 1. Redistributions of source code must retain the above copyright
  46  *    notice, this list of conditions and the following disclaimer.
  47  * 2. Redistributions in binary form must reproduce the above copyright
  48  *    notice, this list of conditions and the following disclaimer in the
  49  *    documentation and/or other materials provided with the distribution.
  50  * 3. Neither the name of the University nor the names of its contributors
  51  *    may be used to endorse or promote products derived from this software
  52  *    without specific prior written permission.
  53  *
  54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  64  * SUCH DAMAGE.
  65  *
  66  *      from: Id: lofs_vfsops.c,v 1.9 1992/05/30 10:26:24 jsp Exp
  67  *      from: @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
  68  *      @(#)null_vfsops.c       8.7 (Berkeley) 5/14/95
  69  */
  70
  71 /*
  72  * Null Layer
  73  * (See null_vnops.c for a description of what this does.)
  74  */
  75
  76 #include <sys/cdefs.h>
  77 __KERNEL_RCSID(0, "$NetBSD: null_vfsops.c,v 1.78 2008/12/05 13:05:37 ad Exp $");
  78
  79 #include <sys/param.h>
  80 #include <sys/systm.h>
  81 #include <sys/sysctl.h>
  82 #include <sys/time.h>
  83 #include <sys/proc.h>
  84 #include <sys/vnode.h>
  85 #include <sys/mount.h>
  86 #include <sys/namei.h>
  87 #include <sys/malloc.h>
  88 #include <sys/module.h>
  89
  90 #include <miscfs/nullfs/null.h>
  91 #include <miscfs/genfs/layer_extern.h>
  92
  93 MODULE(MODULE_CLASS_VFS, nullfs, "layerfs");
  94
  95 VFS_PROTOS(nullfs);
  96
  97 static struct sysctllog *nullfs_sysctl_log;
  98
  99 /*
 100  * Mount null layer
 101  */
 102 int
 103 nullfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
 104 {
 105         struct lwp *l = curlwp;
 106         struct nameidata nd;
 107         struct null_args *args = data;
 108         struct vnode *lowerrootvp, *vp;
 109         struct null_mount *nmp;
 110         struct layer_mount *lmp;
 111         int error = 0;
 112
 113 #ifdef NULLFS_DIAGNOSTIC
 114         printf("nullfs_mount(mp = %p)\n", mp);
 115 #endif
 116
 117         if (*data_len < sizeof *args)
 118                 return EINVAL;
 119
 120         if (mp->mnt_flag & MNT_GETARGS) {
 121                 lmp = MOUNTTOLAYERMOUNT(mp);
 122                 if (lmp == NULL)
 123                         return EIO;
 124                 args->la.target = NULL;
 125                 *data_len = sizeof *args;
 126                 return 0;
 127         }
 128
 129         /*
 130          * Update is not supported
 131          */
 132         if (mp->mnt_flag & MNT_UPDATE)
 133                 return EOPNOTSUPP;
 134
 135         /*
 136          * Find lower node
 137          */
 138         NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, UIO_USERSPACE, args->la.target);
 139         if ((error = namei(&nd)) != 0)
 140                 return (error);
 141
 142         /*
 143          * Sanity check on lower vnode
 144          */
 145         lowerrootvp = nd.ni_vp;
 146
 147         /*
 148          * First cut at fixing up upper mount point
 149          */
 150         nmp = (struct null_mount *) malloc(sizeof(struct null_mount),
 151             M_UFSMNT, M_WAITOK);                /* XXX */
 152         memset(nmp, 0, sizeof(struct null_mount));
 153
 154         mp->mnt_data = nmp;
 155         nmp->nullm_vfs = lowerrootvp->v_mount;
 156         if (nmp->nullm_vfs->mnt_flag & MNT_LOCAL)
 157                 mp->mnt_flag |= MNT_LOCAL;
 158
 159         /*
 160          * Make sure that the mount point is sufficiently initialized
 161          * that the node create call will work.
 162          */
 163         vfs_getnewfsid(mp);
 164
 165         nmp->nullm_size = sizeof(struct null_node);
 166         nmp->nullm_tag = VT_NULL;
 167         nmp->nullm_bypass = layer_bypass;
 168         nmp->nullm_alloc = layer_node_alloc;    /* the default alloc is fine */
 169         nmp->nullm_vnodeop_p = null_vnodeop_p;
 170         mutex_init(&nmp->nullm_hashlock, MUTEX_DEFAULT, IPL_NONE);
 171         nmp->nullm_node_hashtbl = hashinit(desiredvnodes, HASH_LIST, true,
 172             &nmp->nullm_node_hash);
 173
 174         /*
 175          * Fix up null node for root vnode
 176          */
 177         error = layer_node_create(mp, lowerrootvp, &vp);
 178         /*
 179          * Make sure the fixup worked
 180          */
 181         if (error) {
 182                 vput(lowerrootvp);
 183                 hashdone(nmp->nullm_node_hashtbl, HASH_LIST,
 184                     nmp->nullm_node_hash);
 185                 free(nmp, M_UFSMNT);    /* XXX */
 186                 return (error);
 187         }
 188         /*
 189          * Keep a held reference to the root vnode.
 190          * It is vrele'd in nullfs_unmount.
 191          */
 192         vp->v_vflag |= VV_ROOT;
 193         nmp->nullm_rootvp = vp;
 194
 195         /* We don't need kernel_lock. */
 196         mp->mnt_iflag |= IMNT_MPSAFE;
 197
 198         /*
 199          * Unlock the node
 200          */
 201         VOP_UNLOCK(vp, 0);
 202
 203         error = set_statvfs_info(path, UIO_USERSPACE, args->la.target,
 204             UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
 205 #ifdef NULLFS_DIAGNOSTIC
 206         printf("nullfs_mount: lower %s, alias at %s\n",
 207             mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
 208 #endif
 209         return error;
 210 }
 211
 212 /*
 213  * Free reference to null layer
 214  */
 215 int
 216 nullfs_unmount(struct mount *mp, int mntflags)
 217 {
 218         struct null_mount *nmp = MOUNTTONULLMOUNT(mp);
 219         struct vnode *null_rootvp = nmp->nullm_rootvp;
 220         int error;
 221         int flags = 0;
 222
 223 #ifdef NULLFS_DIAGNOSTIC
 224         printf("nullfs_unmount(mp = %p)\n", mp);
 225 #endif
 226
 227         if (mntflags & MNT_FORCE)
 228                 flags |= FORCECLOSE;
 229
 230         if (null_rootvp->v_usecount > 1 && (mntflags & MNT_FORCE) == 0)
 231                 return (EBUSY);
 232         if ((error = vflush(mp, null_rootvp, flags)) != 0)
 233                 return (error);
 234
 235 #ifdef NULLFS_DIAGNOSTIC
 236         vprint("alias root of lower", null_rootvp);
 237 #endif
 238         /*
 239          * Blow it away for future re-use
 240          */
 241         vgone(null_rootvp);
 242
 243         /*
 244          * Finally, throw away the null_mount structure
 245          */
 246         hashdone(nmp->nullm_node_hashtbl, HASH_LIST, nmp->nullm_node_hash);
 247         mutex_destroy(&nmp->nullm_hashlock);
 248         free(mp->mnt_data, M_UFSMNT);   /* XXX */
 249         mp->mnt_data = NULL;
 250         return (0);
 251 }
 252
 253 extern const struct vnodeopv_desc null_vnodeop_opv_desc;
 254
 255 const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = {
 256         &null_vnodeop_opv_desc,
 257         NULL,
 258 };
 259
 260 struct vfsops nullfs_vfsops = {
 261         MOUNT_NULL,
 262         sizeof (struct null_args),
 263         nullfs_mount,
 264         layerfs_start,
 265         nullfs_unmount,
 266         layerfs_root,
 267         layerfs_quotactl,
 268         layerfs_statvfs,
 269         layerfs_sync,
 270         layerfs_vget,
 271         layerfs_fhtovp,
 272         layerfs_vptofh,
 273         layerfs_init,
 274         NULL,
 275         layerfs_done,
 276         NULL,                           /* vfs_mountroot */
 277         layerfs_snapshot,
 278         vfs_stdextattrctl,
 279         (void *)eopnotsupp,             /* vfs_suspendctl */
 280         layerfs_renamelock_enter,
 281         layerfs_renamelock_exit,
 282         (void *)eopnotsupp,
 283         nullfs_vnodeopv_descs,
 284         0,
 285         { NULL, NULL },
 286 };
 287
 288 static int
 289 nullfs_modcmd(modcmd_t cmd, void *arg)
 290 {
 291         int error;
 292
 293         switch (cmd) {
 294         case MODULE_CMD_INIT:
 295                 error = vfs_attach(&nullfs_vfsops);
 296                 if (error != 0)
 297                         break;
 298                 sysctl_createv(&nullfs_sysctl_log, 0, NULL, NULL,
 299                     CTLFLAG_PERMANENT,
 300                     CTLTYPE_NODE, "vfs", NULL,
 301                     NULL, 0, NULL, 0,
 302                     CTL_VFS, CTL_EOL);
 303                 sysctl_createv(&nullfs_sysctl_log, 0, NULL, NULL,
 304                     CTLFLAG_PERMANENT,
 305                     CTLTYPE_NODE, "null",
 306                     SYSCTL_DESCR("Loopback file system"),
 307                     NULL, 0, NULL, 0,
 308                     CTL_VFS, 9, CTL_EOL);
 309                 /*
 310                  * XXX the "9" above could be dynamic, thereby eliminating
 311                  * one more instance of the "number to vfs" mapping problem,
 312                  * but "9" is the order as taken from sys/mount.h
 313                  */
 314                 break;
 315         case MODULE_CMD_FINI:
 316                 error = vfs_detach(&nullfs_vfsops);
 317                 if (error != 0)
 318                         break;
 319                 sysctl_teardown(&nullfs_sysctl_log);
 320                 break;
 321         default:
 322                 error = ENOTTY;
 323                 break;
 324         }
 325
 326         return error;
 327 }