FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_init.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed
8 * to Berkeley by John Heidemann of the UCLA Ficus project.
9 *
10 * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * @(#)vfs_init.c 8.3 (Berkeley) 1/4/94
37 */
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/fnv_hash.h>
45 #include <sys/jail.h>
46 #include <sys/kernel.h>
47 #include <sys/linker.h>
48 #include <sys/mount.h>
49 #include <sys/proc.h>
50 #include <sys/sx.h>
51 #include <sys/syscallsubr.h>
52 #include <sys/sysctl.h>
53 #include <sys/vnode.h>
54 #include <sys/malloc.h>
55
56 static int vfs_register(struct vfsconf *);
57 static int vfs_unregister(struct vfsconf *);
58
59 MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
60
61 /*
62 * The highest defined VFS number.
63 */
64 int maxvfsconf = VFS_GENERIC + 1;
65
66 /*
67 * Single-linked list of configured VFSes.
68 * New entries are added/deleted by vfs_register()/vfs_unregister()
69 */
70 struct vfsconfhead vfsconf = TAILQ_HEAD_INITIALIZER(vfsconf);
71 struct sx vfsconf_sx;
72 SX_SYSINIT(vfsconf, &vfsconf_sx, "vfsconf");
73
74 /*
75 * Loader.conf variable vfs.typenumhash enables setting vfc_typenum using a hash
76 * calculation on vfc_name, so that it doesn't change when file systems are
77 * loaded in a different order. This will avoid the NFS server file handles from
78 * changing for file systems that use vfc_typenum in their fsid.
79 */
80 static int vfs_typenumhash = 1;
81 SYSCTL_INT(_vfs, OID_AUTO, typenumhash, CTLFLAG_RDTUN, &vfs_typenumhash, 0,
82 "Set vfc_typenum using a hash calculation on vfc_name, so that it does not"
83 "change when file systems are loaded in a different order.");
84
85 /*
86 * A Zen vnode attribute structure.
87 *
88 * Initialized when the first filesystem registers by vfs_register().
89 */
90 struct vattr va_null;
91
92 /*
93 * vfs_init.c
94 *
95 * Allocate and fill in operations vectors.
96 *
97 * An undocumented feature of this approach to defining operations is that
98 * there can be multiple entries in vfs_opv_descs for the same operations
99 * vector. This allows third parties to extend the set of operations
100 * supported by another layer in a binary compatibile way. For example,
101 * assume that NFS needed to be modified to support Ficus. NFS has an entry
102 * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
103 * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
104 * listing those new operations Ficus adds to NFS, all without modifying the
105 * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
106 * that is a(whole)nother story.) This is a feature.
107 */
108
109 /*
110 * Routines having to do with the management of the vnode table.
111 */
112
113 static struct vfsconf *
114 vfs_byname_locked(const char *name)
115 {
116 struct vfsconf *vfsp;
117
118 sx_assert(&vfsconf_sx, SA_LOCKED);
119 if (!strcmp(name, "ffs"))
120 name = "ufs";
121 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
122 if (!strcmp(name, vfsp->vfc_name))
123 return (vfsp);
124 }
125 return (NULL);
126 }
127
128 struct vfsconf *
129 vfs_byname(const char *name)
130 {
131 struct vfsconf *vfsp;
132
133 vfsconf_slock();
134 vfsp = vfs_byname_locked(name);
135 vfsconf_sunlock();
136 return (vfsp);
137 }
138
139 struct vfsconf *
140 vfs_byname_kld(const char *fstype, struct thread *td, int *error)
141 {
142 struct vfsconf *vfsp;
143 int fileid, loaded;
144
145 vfsp = vfs_byname(fstype);
146 if (vfsp != NULL)
147 return (vfsp);
148
149 /* Try to load the respective module. */
150 *error = kern_kldload(td, fstype, &fileid);
151 loaded = (*error == 0);
152 if (*error == EEXIST)
153 *error = 0;
154 if (*error)
155 return (NULL);
156
157 /* Look up again to see if the VFS was loaded. */
158 vfsp = vfs_byname(fstype);
159 if (vfsp == NULL) {
160 if (loaded)
161 (void)kern_kldunload(td, fileid, LINKER_UNLOAD_FORCE);
162 *error = ENODEV;
163 return (NULL);
164 }
165 return (vfsp);
166 }
167
168
169 /* Register a new filesystem type in the global table */
170 static int
171 vfs_register(struct vfsconf *vfc)
172 {
173 struct sysctl_oid *oidp;
174 struct vfsops *vfsops;
175 static int once;
176 struct vfsconf *tvfc;
177 uint32_t hashval;
178 int secondpass;
179
180 if (!once) {
181 vattr_null(&va_null);
182 once = 1;
183 }
184
185 if (vfc->vfc_version != VFS_VERSION) {
186 printf("ERROR: filesystem %s, unsupported ABI version %x\n",
187 vfc->vfc_name, vfc->vfc_version);
188 return (EINVAL);
189 }
190 vfsconf_lock();
191 if (vfs_byname_locked(vfc->vfc_name) != NULL) {
192 vfsconf_unlock();
193 return (EEXIST);
194 }
195
196 if (vfs_typenumhash != 0) {
197 /*
198 * Calculate a hash on vfc_name to use for vfc_typenum. Unless
199 * all of 1<->255 are assigned, it is limited to 8bits since
200 * that is what ZFS uses from vfc_typenum and is also the
201 * preferred range for vfs_getnewfsid().
202 */
203 hashval = fnv_32_str(vfc->vfc_name, FNV1_32_INIT);
204 hashval &= 0xff;
205 secondpass = 0;
206 do {
207 /* Look for and fix any collision. */
208 TAILQ_FOREACH(tvfc, &vfsconf, vfc_list) {
209 if (hashval == tvfc->vfc_typenum) {
210 if (hashval == 255 && secondpass == 0) {
211 hashval = 1;
212 secondpass = 1;
213 } else
214 hashval++;
215 break;
216 }
217 }
218 } while (tvfc != NULL);
219 vfc->vfc_typenum = hashval;
220 if (vfc->vfc_typenum >= maxvfsconf)
221 maxvfsconf = vfc->vfc_typenum + 1;
222 } else
223 vfc->vfc_typenum = maxvfsconf++;
224 TAILQ_INSERT_TAIL(&vfsconf, vfc, vfc_list);
225
226 /*
227 * Initialise unused ``struct vfsops'' fields, to use
228 * the vfs_std*() functions. Note, we need the mount
229 * and unmount operations, at the least. The check
230 * for vfsops available is just a debugging aid.
231 */
232 KASSERT(vfc->vfc_vfsops != NULL,
233 ("Filesystem %s has no vfsops", vfc->vfc_name));
234 /*
235 * Check the mount and unmount operations.
236 */
237 vfsops = vfc->vfc_vfsops;
238 KASSERT(vfsops->vfs_mount != NULL,
239 ("Filesystem %s has no mount op", vfc->vfc_name));
240 KASSERT(vfsops->vfs_unmount != NULL,
241 ("Filesystem %s has no unmount op", vfc->vfc_name));
242
243 if (vfsops->vfs_root == NULL)
244 /* return file system's root vnode */
245 vfsops->vfs_root = vfs_stdroot;
246 if (vfsops->vfs_quotactl == NULL)
247 /* quota control */
248 vfsops->vfs_quotactl = vfs_stdquotactl;
249 if (vfsops->vfs_statfs == NULL)
250 /* return file system's status */
251 vfsops->vfs_statfs = vfs_stdstatfs;
252 if (vfsops->vfs_sync == NULL)
253 /*
254 * flush unwritten data (nosync)
255 * file systems can use vfs_stdsync
256 * explicitly by setting it in the
257 * vfsop vector.
258 */
259 vfsops->vfs_sync = vfs_stdnosync;
260 if (vfsops->vfs_vget == NULL)
261 /* convert an inode number to a vnode */
262 vfsops->vfs_vget = vfs_stdvget;
263 if (vfsops->vfs_fhtovp == NULL)
264 /* turn an NFS file handle into a vnode */
265 vfsops->vfs_fhtovp = vfs_stdfhtovp;
266 if (vfsops->vfs_checkexp == NULL)
267 /* check if file system is exported */
268 vfsops->vfs_checkexp = vfs_stdcheckexp;
269 if (vfsops->vfs_init == NULL)
270 /* file system specific initialisation */
271 vfsops->vfs_init = vfs_stdinit;
272 if (vfsops->vfs_uninit == NULL)
273 /* file system specific uninitialisation */
274 vfsops->vfs_uninit = vfs_stduninit;
275 if (vfsops->vfs_extattrctl == NULL)
276 /* extended attribute control */
277 vfsops->vfs_extattrctl = vfs_stdextattrctl;
278 if (vfsops->vfs_sysctl == NULL)
279 vfsops->vfs_sysctl = vfs_stdsysctl;
280
281 if (vfc->vfc_flags & VFCF_JAIL)
282 prison_add_vfs(vfc);
283
284 /*
285 * Call init function for this VFS...
286 */
287 (*(vfc->vfc_vfsops->vfs_init))(vfc);
288 vfsconf_unlock();
289
290 /*
291 * If this filesystem has a sysctl node under vfs
292 * (i.e. vfs.xxfs), then change the oid number of that node to
293 * match the filesystem's type number. This allows user code
294 * which uses the type number to read sysctl variables defined
295 * by the filesystem to continue working. Since the oids are
296 * in a sorted list, we need to make sure the order is
297 * preserved by re-registering the oid after modifying its
298 * number.
299 */
300 sysctl_wlock();
301 SLIST_FOREACH(oidp, SYSCTL_CHILDREN(&sysctl___vfs), oid_link) {
302 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
303 sysctl_unregister_oid(oidp);
304 oidp->oid_number = vfc->vfc_typenum;
305 sysctl_register_oid(oidp);
306 break;
307 }
308 }
309 sysctl_wunlock();
310
311 return (0);
312 }
313
314
315 /* Remove registration of a filesystem type */
316 static int
317 vfs_unregister(struct vfsconf *vfc)
318 {
319 struct vfsconf *vfsp;
320 int error, maxtypenum;
321
322 vfsconf_lock();
323 vfsp = vfs_byname_locked(vfc->vfc_name);
324 if (vfsp == NULL) {
325 vfsconf_unlock();
326 return (EINVAL);
327 }
328 if (vfsp->vfc_refcount != 0) {
329 vfsconf_unlock();
330 return (EBUSY);
331 }
332 if (vfc->vfc_vfsops->vfs_uninit != NULL) {
333 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
334 if (error != 0) {
335 vfsconf_unlock();
336 return (error);
337 }
338 }
339 TAILQ_REMOVE(&vfsconf, vfsp, vfc_list);
340 maxtypenum = VFS_GENERIC;
341 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
342 if (maxtypenum < vfsp->vfc_typenum)
343 maxtypenum = vfsp->vfc_typenum;
344 maxvfsconf = maxtypenum + 1;
345 vfsconf_unlock();
346 return (0);
347 }
348
349 /*
350 * Standard kernel module handling code for filesystem modules.
351 * Referenced from VFS_SET().
352 */
353 int
354 vfs_modevent(module_t mod, int type, void *data)
355 {
356 struct vfsconf *vfc;
357 int error = 0;
358
359 vfc = (struct vfsconf *)data;
360
361 switch (type) {
362 case MOD_LOAD:
363 if (vfc)
364 error = vfs_register(vfc);
365 break;
366
367 case MOD_UNLOAD:
368 if (vfc)
369 error = vfs_unregister(vfc);
370 break;
371 default:
372 error = EOPNOTSUPP;
373 break;
374 }
375 return (error);
376 }
Cache object: 695c391952a3944f33486d007e29c413
|