vfs_init.c revision 267992
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: head/sys/kern/vfs_init.c 267992 2014-06-28 03:56:17Z hselasky $"); 39 40#include <sys/param.h> 41#include <sys/systm.h> 42#include <sys/fnv_hash.h> 43#include <sys/kernel.h> 44#include <sys/linker.h> 45#include <sys/mount.h> 46#include <sys/proc.h> 47#include <sys/syscallsubr.h> 48#include <sys/sysctl.h> 49#include <sys/vnode.h> 50#include <sys/malloc.h> 51 52static int vfs_register(struct vfsconf *); 53static int vfs_unregister(struct vfsconf *); 54 55MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes"); 56 57/* 58 * The highest defined VFS number. 59 */ 60int maxvfsconf = VFS_GENERIC + 1; 61 62/* 63 * Single-linked list of configured VFSes. 64 * New entries are added/deleted by vfs_register()/vfs_unregister() 65 */ 66struct vfsconfhead vfsconf = TAILQ_HEAD_INITIALIZER(vfsconf); 67 68/* 69 * Loader.conf variable vfs.typenumhash enables setting vfc_typenum using a hash 70 * calculation on vfc_name, so that it doesn't change when file systems are 71 * loaded in a different order. This will avoid the NFS server file handles from 72 * changing for file systems that use vfc_typenum in their fsid. 73 */ 74static int vfs_typenumhash = 1; 75SYSCTL_INT(_vfs, OID_AUTO, typenumhash, CTLFLAG_RDTUN, &vfs_typenumhash, 0, 76 "Set vfc_typenum using a hash calculation on vfc_name, so that it does not" 77 "change when file systems are loaded in a different order."); 78 79/* 80 * A Zen vnode attribute structure. 81 * 82 * Initialized when the first filesystem registers by vfs_register(). 83 */ 84struct vattr va_null; 85 86/* 87 * vfs_init.c 88 * 89 * Allocate and fill in operations vectors. 90 * 91 * An undocumented feature of this approach to defining operations is that 92 * there can be multiple entries in vfs_opv_descs for the same operations 93 * vector. This allows third parties to extend the set of operations 94 * supported by another layer in a binary compatibile way. For example, 95 * assume that NFS needed to be modified to support Ficus. NFS has an entry 96 * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by 97 * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions) 98 * listing those new operations Ficus adds to NFS, all without modifying the 99 * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but 100 * that is a(whole)nother story.) This is a feature. 101 */ 102 103/* 104 * Routines having to do with the management of the vnode table. 105 */ 106 107struct vfsconf * 108vfs_byname(const char *name) 109{ 110 struct vfsconf *vfsp; 111 112 if (!strcmp(name, "ffs")) 113 name = "ufs"; 114 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) 115 if (!strcmp(name, vfsp->vfc_name)) 116 return (vfsp); 117 return (NULL); 118} 119 120struct vfsconf * 121vfs_byname_kld(const char *fstype, struct thread *td, int *error) 122{ 123 struct vfsconf *vfsp; 124 int fileid, loaded; 125 126 vfsp = vfs_byname(fstype); 127 if (vfsp != NULL) 128 return (vfsp); 129 130 /* Try to load the respective module. */ 131 *error = kern_kldload(td, fstype, &fileid); 132 loaded = (*error == 0); 133 if (*error == EEXIST) 134 *error = 0; 135 if (*error) 136 return (NULL); 137 138 /* Look up again to see if the VFS was loaded. */ 139 vfsp = vfs_byname(fstype); 140 if (vfsp == NULL) { 141 if (loaded) 142 (void)kern_kldunload(td, fileid, LINKER_UNLOAD_FORCE); 143 *error = ENODEV; 144 return (NULL); 145 } 146 return (vfsp); 147} 148 149 150/* Register a new filesystem type in the global table */ 151static int 152vfs_register(struct vfsconf *vfc) 153{ 154 struct sysctl_oid *oidp; 155 struct vfsops *vfsops; 156 static int once; 157 struct vfsconf *tvfc; 158 uint32_t hashval; 159 int secondpass; 160 161 if (!once) { 162 vattr_null(&va_null); 163 once = 1; 164 } 165 166 if (vfc->vfc_version != VFS_VERSION) { 167 printf("ERROR: filesystem %s, unsupported ABI version %x\n", 168 vfc->vfc_name, vfc->vfc_version); 169 return (EINVAL); 170 } 171 if (vfs_byname(vfc->vfc_name) != NULL) 172 return (EEXIST); 173 174 if (vfs_typenumhash != 0) { 175 /* 176 * Calculate a hash on vfc_name to use for vfc_typenum. Unless 177 * all of 1<->255 are assigned, it is limited to 8bits since 178 * that is what ZFS uses from vfc_typenum and is also the 179 * preferred range for vfs_getnewfsid(). 180 */ 181 hashval = fnv_32_str(vfc->vfc_name, FNV1_32_INIT); 182 hashval &= 0xff; 183 secondpass = 0; 184 do { 185 /* Look for and fix any collision. */ 186 TAILQ_FOREACH(tvfc, &vfsconf, vfc_list) { 187 if (hashval == tvfc->vfc_typenum) { 188 if (hashval == 255 && secondpass == 0) { 189 hashval = 1; 190 secondpass = 1; 191 } else 192 hashval++; 193 break; 194 } 195 } 196 } while (tvfc != NULL); 197 vfc->vfc_typenum = hashval; 198 if (vfc->vfc_typenum >= maxvfsconf) 199 maxvfsconf = vfc->vfc_typenum + 1; 200 } else 201 vfc->vfc_typenum = maxvfsconf++; 202 TAILQ_INSERT_TAIL(&vfsconf, vfc, vfc_list); 203 204 /* 205 * If this filesystem has a sysctl node under vfs 206 * (i.e. vfs.xxfs), then change the oid number of that node to 207 * match the filesystem's type number. This allows user code 208 * which uses the type number to read sysctl variables defined 209 * by the filesystem to continue working. Since the oids are 210 * in a sorted list, we need to make sure the order is 211 * preserved by re-registering the oid after modifying its 212 * number. 213 */ 214 sysctl_lock(); 215 SLIST_FOREACH(oidp, SYSCTL_CHILDREN(&sysctl___vfs), oid_link) 216 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) { 217 sysctl_unregister_oid(oidp); 218 oidp->oid_number = vfc->vfc_typenum; 219 sysctl_register_oid(oidp); 220 break; 221 } 222 sysctl_unlock(); 223 224 /* 225 * Initialise unused ``struct vfsops'' fields, to use 226 * the vfs_std*() functions. Note, we need the mount 227 * and unmount operations, at the least. The check 228 * for vfsops available is just a debugging aid. 229 */ 230 KASSERT(vfc->vfc_vfsops != NULL, 231 ("Filesystem %s has no vfsops", vfc->vfc_name)); 232 /* 233 * Check the mount and unmount operations. 234 */ 235 vfsops = vfc->vfc_vfsops; 236 KASSERT(vfsops->vfs_mount != NULL, 237 ("Filesystem %s has no mount op", vfc->vfc_name)); 238 KASSERT(vfsops->vfs_unmount != NULL, 239 ("Filesystem %s has no unmount op", vfc->vfc_name)); 240 241 if (vfsops->vfs_root == NULL) 242 /* return file system's root vnode */ 243 vfsops->vfs_root = vfs_stdroot; 244 if (vfsops->vfs_quotactl == NULL) 245 /* quota control */ 246 vfsops->vfs_quotactl = vfs_stdquotactl; 247 if (vfsops->vfs_statfs == NULL) 248 /* return file system's status */ 249 vfsops->vfs_statfs = vfs_stdstatfs; 250 if (vfsops->vfs_sync == NULL) 251 /* 252 * flush unwritten data (nosync) 253 * file systems can use vfs_stdsync 254 * explicitly by setting it in the 255 * vfsop vector. 256 */ 257 vfsops->vfs_sync = vfs_stdnosync; 258 if (vfsops->vfs_vget == NULL) 259 /* convert an inode number to a vnode */ 260 vfsops->vfs_vget = vfs_stdvget; 261 if (vfsops->vfs_fhtovp == NULL) 262 /* turn an NFS file handle into a vnode */ 263 vfsops->vfs_fhtovp = vfs_stdfhtovp; 264 if (vfsops->vfs_checkexp == NULL) 265 /* check if file system is exported */ 266 vfsops->vfs_checkexp = vfs_stdcheckexp; 267 if (vfsops->vfs_init == NULL) 268 /* file system specific initialisation */ 269 vfsops->vfs_init = vfs_stdinit; 270 if (vfsops->vfs_uninit == NULL) 271 /* file system specific uninitialisation */ 272 vfsops->vfs_uninit = vfs_stduninit; 273 if (vfsops->vfs_extattrctl == NULL) 274 /* extended attribute control */ 275 vfsops->vfs_extattrctl = vfs_stdextattrctl; 276 if (vfsops->vfs_sysctl == NULL) 277 vfsops->vfs_sysctl = vfs_stdsysctl; 278 279 /* 280 * Call init function for this VFS... 281 */ 282 (*(vfc->vfc_vfsops->vfs_init))(vfc); 283 284 return 0; 285} 286 287 288/* Remove registration of a filesystem type */ 289static int 290vfs_unregister(struct vfsconf *vfc) 291{ 292 struct vfsconf *vfsp; 293 int error, i, maxtypenum; 294 295 i = vfc->vfc_typenum; 296 297 vfsp = vfs_byname(vfc->vfc_name); 298 if (vfsp == NULL) 299 return EINVAL; 300 if (vfsp->vfc_refcount) 301 return EBUSY; 302 if (vfc->vfc_vfsops->vfs_uninit != NULL) { 303 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp); 304 if (error) 305 return (error); 306 } 307 TAILQ_REMOVE(&vfsconf, vfsp, vfc_list); 308 maxtypenum = VFS_GENERIC; 309 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) 310 if (maxtypenum < vfsp->vfc_typenum) 311 maxtypenum = vfsp->vfc_typenum; 312 maxvfsconf = maxtypenum + 1; 313 return 0; 314} 315 316/* 317 * Standard kernel module handling code for filesystem modules. 318 * Referenced from VFS_SET(). 319 */ 320int 321vfs_modevent(module_t mod, int type, void *data) 322{ 323 struct vfsconf *vfc; 324 int error = 0; 325 326 vfc = (struct vfsconf *)data; 327 328 switch (type) { 329 case MOD_LOAD: 330 if (vfc) 331 error = vfs_register(vfc); 332 break; 333 334 case MOD_UNLOAD: 335 if (vfc) 336 error = vfs_unregister(vfc); 337 break; 338 default: 339 error = EOPNOTSUPP; 340 break; 341 } 342 return (error); 343} 344