sys/kern/vfs_init.c

   1 /*-
   2  * Copyright (c) 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed
   6  * to Berkeley by John Heidemann of the UCLA Ficus project.
   7  *
   8  * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
   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  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)vfs_init.c  8.3 (Berkeley) 1/4/94
  35  */
  36
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD$");
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/kernel.h>
  43 #include <sys/linker.h>
  44 #include <sys/mount.h>
  45 #include <sys/proc.h>
  46 #include <sys/syscallsubr.h>
  47 #include <sys/sysctl.h>
  48 #include <sys/vnode.h>
  49 #include <sys/malloc.h>
  50
  51 static int      vfs_register(struct vfsconf *);
  52 static int      vfs_unregister(struct vfsconf *);
  53
  54 MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
  55
  56 /*
  57  * The highest defined VFS number.
  58  */
  59 int maxvfsconf = VFS_GENERIC + 1;
  60
  61 /*
  62  * Single-linked list of configured VFSes.
  63  * New entries are added/deleted by vfs_register()/vfs_unregister()
  64  */
  65 struct vfsconfhead vfsconf = TAILQ_HEAD_INITIALIZER(vfsconf);
  66
  67 /*
  68  * A Zen vnode attribute structure.
  69  *
  70  * Initialized when the first filesystem registers by vfs_register().
  71  */
  72 struct vattr va_null;
  73
  74 /*
  75  * vfs_init.c
  76  *
  77  * Allocate and fill in operations vectors.
  78  *
  79  * An undocumented feature of this approach to defining operations is that
  80  * there can be multiple entries in vfs_opv_descs for the same operations
  81  * vector. This allows third parties to extend the set of operations
  82  * supported by another layer in a binary compatibile way. For example,
  83  * assume that NFS needed to be modified to support Ficus. NFS has an entry
  84  * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
  85  * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
  86  * listing those new operations Ficus adds to NFS, all without modifying the
  87  * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
  88  * that is a(whole)nother story.) This is a feature.
  89  */
  90
  91 /*
  92  * Routines having to do with the management of the vnode table.
  93  */
  94
  95 struct vfsconf *
  96 vfs_byname(const char *name)
  97 {
  98         struct vfsconf *vfsp;
  99
 100         if (!strcmp(name, "ffs"))
 101                 name = "ufs";
 102         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
 103                 if (!strcmp(name, vfsp->vfc_name))
 104                         return (vfsp);
 105         return (NULL);
 106 }
 107
 108 struct vfsconf *
 109 vfs_byname_kld(const char *fstype, struct thread *td, int *error)
 110 {
 111         struct vfsconf *vfsp;
 112         int fileid;
 113
 114         vfsp = vfs_byname(fstype);
 115         if (vfsp != NULL)
 116                 return (vfsp);
 117
 118         /* Try to load the respective module. */
 119         *error = kern_kldload(td, fstype, &fileid);
 120         if (*error)
 121                 return (NULL);
 122
 123         /* Look up again to see if the VFS was loaded. */
 124         vfsp = vfs_byname(fstype);
 125         if (vfsp == NULL) {
 126                 (void)kern_kldunload(td, fileid, LINKER_UNLOAD_FORCE);
 127                 *error = ENODEV;
 128                 return (NULL);
 129         }
 130         return (vfsp);
 131 }
 132
 133
 134 /* Register a new filesystem type in the global table */
 135 static int
 136 vfs_register(struct vfsconf *vfc)
 137 {
 138         struct sysctl_oid *oidp;
 139         struct vfsops *vfsops;
 140         static int once;
 141
 142         if (!once) {
 143                 vattr_null(&va_null);
 144                 once = 1;
 145         }
 146
 147         if (vfc->vfc_version != VFS_VERSION) {
 148                 printf("ERROR: filesystem %s, unsupported ABI version %x\n",
 149                     vfc->vfc_name, vfc->vfc_version);
 150                 return (EINVAL);
 151         }
 152         if (vfs_byname(vfc->vfc_name) != NULL)
 153                 return EEXIST;
 154
 155         vfc->vfc_typenum = maxvfsconf++;
 156         TAILQ_INSERT_TAIL(&vfsconf, vfc, vfc_list);
 157
 158         /*
 159          * If this filesystem has a sysctl node under vfs
 160          * (i.e. vfs.xxfs), then change the oid number of that node to
 161          * match the filesystem's type number.  This allows user code
 162          * which uses the type number to read sysctl variables defined
 163          * by the filesystem to continue working. Since the oids are
 164          * in a sorted list, we need to make sure the order is
 165          * preserved by re-registering the oid after modifying its
 166          * number.
 167          */
 168         SLIST_FOREACH(oidp, &sysctl__vfs_children, oid_link)
 169                 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
 170                         sysctl_unregister_oid(oidp);
 171                         oidp->oid_number = vfc->vfc_typenum;
 172                         sysctl_register_oid(oidp);
 173                 }
 174
 175         /*
 176          * Initialise unused ``struct vfsops'' fields, to use
 177          * the vfs_std*() functions.  Note, we need the mount
 178          * and unmount operations, at the least.  The check
 179          * for vfsops available is just a debugging aid.
 180          */
 181         KASSERT(vfc->vfc_vfsops != NULL,
 182             ("Filesystem %s has no vfsops", vfc->vfc_name));
 183         /*
 184          * Check the mount and unmount operations.
 185          */
 186         vfsops = vfc->vfc_vfsops;
 187         KASSERT(vfsops->vfs_mount != NULL,
 188             ("Filesystem %s has no mount op", vfc->vfc_name));
 189         KASSERT(vfsops->vfs_unmount != NULL,
 190             ("Filesystem %s has no unmount op", vfc->vfc_name));
 191
 192         if (vfsops->vfs_root == NULL)
 193                 /* return file system's root vnode */
 194                 vfsops->vfs_root =      vfs_stdroot;
 195         if (vfsops->vfs_quotactl == NULL)
 196                 /* quota control */
 197                 vfsops->vfs_quotactl =  vfs_stdquotactl;
 198         if (vfsops->vfs_statfs == NULL)
 199                 /* return file system's status */
 200                 vfsops->vfs_statfs =    vfs_stdstatfs;
 201         if (vfsops->vfs_sync == NULL)
 202                 /*
 203                  * flush unwritten data (nosync)
 204                  * file systems can use vfs_stdsync
 205                  * explicitly by setting it in the
 206                  * vfsop vector.
 207                  */
 208                 vfsops->vfs_sync =      vfs_stdnosync;
 209         if (vfsops->vfs_vget == NULL)
 210                 /* convert an inode number to a vnode */
 211                 vfsops->vfs_vget =      vfs_stdvget;
 212         if (vfsops->vfs_fhtovp == NULL)
 213                 /* turn an NFS file handle into a vnode */
 214                 vfsops->vfs_fhtovp =    vfs_stdfhtovp;
 215         if (vfsops->vfs_checkexp == NULL)
 216                 /* check if file system is exported */
 217                 vfsops->vfs_checkexp =  vfs_stdcheckexp;
 218         if (vfsops->vfs_init == NULL)
 219                 /* file system specific initialisation */
 220                 vfsops->vfs_init =      vfs_stdinit;
 221         if (vfsops->vfs_uninit == NULL)
 222                 /* file system specific uninitialisation */
 223                 vfsops->vfs_uninit =    vfs_stduninit;
 224         if (vfsops->vfs_extattrctl == NULL)
 225                 /* extended attribute control */
 226                 vfsops->vfs_extattrctl = vfs_stdextattrctl;
 227         if (vfsops->vfs_sysctl == NULL)
 228                 vfsops->vfs_sysctl = vfs_stdsysctl;
 229
 230         /*
 231          * Call init function for this VFS...
 232          */
 233         (*(vfc->vfc_vfsops->vfs_init))(vfc);
 234
 235         return 0;
 236 }
 237
 238
 239 /* Remove registration of a filesystem type */
 240 static int
 241 vfs_unregister(struct vfsconf *vfc)
 242 {
 243         struct vfsconf *vfsp;
 244         int error, i, maxtypenum;
 245
 246         i = vfc->vfc_typenum;
 247
 248         vfsp = vfs_byname(vfc->vfc_name);
 249         if (vfsp == NULL)
 250                 return EINVAL;
 251         if (vfsp->vfc_refcount)
 252                 return EBUSY;
 253         if (vfc->vfc_vfsops->vfs_uninit != NULL) {
 254                 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
 255                 if (error)
 256                         return (error);
 257         }
 258         TAILQ_REMOVE(&vfsconf, vfsp, vfc_list);
 259         maxtypenum = VFS_GENERIC;
 260         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
 261                 if (maxtypenum < vfsp->vfc_typenum)
 262                         maxtypenum = vfsp->vfc_typenum;
 263         maxvfsconf = maxtypenum + 1;
 264         return 0;
 265 }
 266
 267 /*
 268  * Standard kernel module handling code for filesystem modules.
 269  * Referenced from VFS_SET().
 270  */
 271 int
 272 vfs_modevent(module_t mod, int type, void *data)
 273 {
 274         struct vfsconf *vfc;
 275         int error = 0;
 276
 277         vfc = (struct vfsconf *)data;
 278
 279         switch (type) {
 280         case MOD_LOAD:
 281                 if (vfc)
 282                         error = vfs_register(vfc);
 283                 break;
 284
 285         case MOD_UNLOAD:
 286                 if (vfc)
 287                         error = vfs_unregister(vfc);
 288                 break;
 289         default:
 290                 error = EOPNOTSUPP;
 291                 break;
 292         }
 293         return (error);
 294 }