FreeBSD/Linux Kernel Cross Reference
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/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/sx.h>
48 #include <sys/syscallsubr.h>
49 #include <sys/sysctl.h>
50 #include <sys/vnode.h>
51 #include <sys/malloc.h>
52
53 static int vfs_register(struct vfsconf *);
54 static int vfs_unregister(struct vfsconf *);
55
56 MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
57
58 /*
59 * The highest defined VFS number.
60 */
61 int maxvfsconf = VFS_GENERIC + 1;
62
63 /*
64 * Single-linked list of configured VFSes.
65 * New entries are added/deleted by vfs_register()/vfs_unregister()
66 */
67 struct vfsconfhead vfsconf = TAILQ_HEAD_INITIALIZER(vfsconf);
68 struct sx vfsconf_sx;
69 SX_SYSINIT(vfsconf, &vfsconf_sx, "vfsconf");
70
71 /*
72 * Loader.conf variable vfs.typenumhash enables setting vfc_typenum using a hash
73 * calculation on vfc_name, so that it doesn't change when file systems are
74 * loaded in a different order. This will avoid the NFS server file handles from
75 * changing for file systems that use vfc_typenum in their fsid.
76 */
77 static int vfs_typenumhash = 1;
78 SYSCTL_INT(_vfs, OID_AUTO, typenumhash, CTLFLAG_RDTUN, &vfs_typenumhash, 0,
79 "Set vfc_typenum using a hash calculation on vfc_name, so that it does not"
80 "change when file systems are loaded in a different order.");
81
82 /*
83 * A Zen vnode attribute structure.
84 *
85 * Initialized when the first filesystem registers by vfs_register().
86 */
87 struct vattr va_null;
88
89 /*
90 * vfs_init.c
91 *
92 * Allocate and fill in operations vectors.
93 *
94 * An undocumented feature of this approach to defining operations is that
95 * there can be multiple entries in vfs_opv_descs for the same operations
96 * vector. This allows third parties to extend the set of operations
97 * supported by another layer in a binary compatibile way. For example,
98 * assume that NFS needed to be modified to support Ficus. NFS has an entry
99 * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
100 * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
101 * listing those new operations Ficus adds to NFS, all without modifying the
102 * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
103 * that is a(whole)nother story.) This is a feature.
104 */
105
106 /*
107 * Routines having to do with the management of the vnode table.
108 */
109
110 static struct vfsconf *
111 vfs_byname_locked(const char *name)
112 {
113 struct vfsconf *vfsp;
114
115 sx_assert(&vfsconf_sx, SA_LOCKED);
116 if (!strcmp(name, "ffs"))
117 name = "ufs";
118 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
119 if (!strcmp(name, vfsp->vfc_name))
120 return (vfsp);
121 }
122 return (NULL);
123 }
124
125 struct vfsconf *
126 vfs_byname(const char *name)
127 {
128 struct vfsconf *vfsp;
129
130 vfsconf_slock();
131 vfsp = vfs_byname_locked(name);
132 vfsconf_sunlock();
133 return (vfsp);
134 }
135
136 struct vfsconf *
137 vfs_byname_kld(const char *fstype, struct thread *td, int *error)
138 {
139 struct vfsconf *vfsp;
140 int fileid, loaded;
141
142 vfsp = vfs_byname(fstype);
143 if (vfsp != NULL)
144 return (vfsp);
145
146 /* Try to load the respective module. */
147 *error = kern_kldload(td, fstype, &fileid);
148 loaded = (*error == 0);
149 if (*error == EEXIST)
150 *error = 0;
151 if (*error)
152 return (NULL);
153
154 /* Look up again to see if the VFS was loaded. */
155 vfsp = vfs_byname(fstype);
156 if (vfsp == NULL) {
157 if (loaded)
158 (void)kern_kldunload(td, fileid, LINKER_UNLOAD_FORCE);
159 *error = ENODEV;
160 return (NULL);
161 }
162 return (vfsp);
163 }
164
165
166 /* Register a new filesystem type in the global table */
167 static int
168 vfs_register(struct vfsconf *vfc)
169 {
170 struct sysctl_oid *oidp;
171 struct vfsops *vfsops;
172 static int once;
173 struct vfsconf *tvfc;
174 uint32_t hashval;
175 int secondpass;
176
177 if (!once) {
178 vattr_null(&va_null);
179 once = 1;
180 }
181
182 if (vfc->vfc_version != VFS_VERSION) {
183 printf("ERROR: filesystem %s, unsupported ABI version %x\n",
184 vfc->vfc_name, vfc->vfc_version);
185 return (EINVAL);
186 }
187 vfsconf_lock();
188 if (vfs_byname_locked(vfc->vfc_name) != NULL) {
189 vfsconf_unlock();
190 return (EEXIST);
191 }
192
193 if (vfs_typenumhash != 0) {
194 /*
195 * Calculate a hash on vfc_name to use for vfc_typenum. Unless
196 * all of 1<->255 are assigned, it is limited to 8bits since
197 * that is what ZFS uses from vfc_typenum and is also the
198 * preferred range for vfs_getnewfsid().
199 */
200 hashval = fnv_32_str(vfc->vfc_name, FNV1_32_INIT);
201 hashval &= 0xff;
202 secondpass = 0;
203 do {
204 /* Look for and fix any collision. */
205 TAILQ_FOREACH(tvfc, &vfsconf, vfc_list) {
206 if (hashval == tvfc->vfc_typenum) {
207 if (hashval == 255 && secondpass == 0) {
208 hashval = 1;
209 secondpass = 1;
210 } else
211 hashval++;
212 break;
213 }
214 }
215 } while (tvfc != NULL);
216 vfc->vfc_typenum = hashval;
217 if (vfc->vfc_typenum >= maxvfsconf)
218 maxvfsconf = vfc->vfc_typenum + 1;
219 } else
220 vfc->vfc_typenum = maxvfsconf++;
221 TAILQ_INSERT_TAIL(&vfsconf, vfc, vfc_list);
222
223 /*
224 * Initialise unused ``struct vfsops'' fields, to use
225 * the vfs_std*() functions. Note, we need the mount
226 * and unmount operations, at the least. The check
227 * for vfsops available is just a debugging aid.
228 */
229 KASSERT(vfc->vfc_vfsops != NULL,
230 ("Filesystem %s has no vfsops", vfc->vfc_name));
231 /*
232 * Check the mount and unmount operations.
233 */
234 vfsops = vfc->vfc_vfsops;
235 KASSERT(vfsops->vfs_mount != NULL,
236 ("Filesystem %s has no mount op", vfc->vfc_name));
237 KASSERT(vfsops->vfs_unmount != NULL,
238 ("Filesystem %s has no unmount op", vfc->vfc_name));
239
240 if (vfsops->vfs_root == NULL)
241 /* return file system's root vnode */
242 vfsops->vfs_root = vfs_stdroot;
243 if (vfsops->vfs_quotactl == NULL)
244 /* quota control */
245 vfsops->vfs_quotactl = vfs_stdquotactl;
246 if (vfsops->vfs_statfs == NULL)
247 /* return file system's status */
248 vfsops->vfs_statfs = vfs_stdstatfs;
249 if (vfsops->vfs_sync == NULL)
250 /*
251 * flush unwritten data (nosync)
252 * file systems can use vfs_stdsync
253 * explicitly by setting it in the
254 * vfsop vector.
255 */
256 vfsops->vfs_sync = vfs_stdnosync;
257 if (vfsops->vfs_vget == NULL)
258 /* convert an inode number to a vnode */
259 vfsops->vfs_vget = vfs_stdvget;
260 if (vfsops->vfs_fhtovp == NULL)
261 /* turn an NFS file handle into a vnode */
262 vfsops->vfs_fhtovp = vfs_stdfhtovp;
263 if (vfsops->vfs_checkexp == NULL)
264 /* check if file system is exported */
265 vfsops->vfs_checkexp = vfs_stdcheckexp;
266 if (vfsops->vfs_init == NULL)
267 /* file system specific initialisation */
268 vfsops->vfs_init = vfs_stdinit;
269 if (vfsops->vfs_uninit == NULL)
270 /* file system specific uninitialisation */
271 vfsops->vfs_uninit = vfs_stduninit;
272 if (vfsops->vfs_extattrctl == NULL)
273 /* extended attribute control */
274 vfsops->vfs_extattrctl = vfs_stdextattrctl;
275 if (vfsops->vfs_sysctl == NULL)
276 vfsops->vfs_sysctl = vfs_stdsysctl;
277
278 /*
279 * Call init function for this VFS...
280 */
281 (*(vfc->vfc_vfsops->vfs_init))(vfc);
282 vfsconf_unlock();
283
284 /*
285 * If this filesystem has a sysctl node under vfs
286 * (i.e. vfs.xxfs), then change the oid number of that node to
287 * match the filesystem's type number. This allows user code
288 * which uses the type number to read sysctl variables defined
289 * by the filesystem to continue working. Since the oids are
290 * in a sorted list, we need to make sure the order is
291 * preserved by re-registering the oid after modifying its
292 * number.
293 */
294 sysctl_wlock();
295 SLIST_FOREACH(oidp, SYSCTL_CHILDREN(&sysctl___vfs), oid_link) {
296 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
297 sysctl_unregister_oid(oidp);
298 oidp->oid_number = vfc->vfc_typenum;
299 sysctl_register_oid(oidp);
300 break;
301 }
302 }
303 sysctl_wunlock();
304
305 return (0);
306 }
307
308
309 /* Remove registration of a filesystem type */
310 static int
311 vfs_unregister(struct vfsconf *vfc)
312 {
313 struct vfsconf *vfsp;
314 int error, maxtypenum;
315
316 vfsconf_lock();
317 vfsp = vfs_byname_locked(vfc->vfc_name);
318 if (vfsp == NULL) {
319 vfsconf_unlock();
320 return (EINVAL);
321 }
322 if (vfsp->vfc_refcount != 0) {
323 vfsconf_unlock();
324 return (EBUSY);
325 }
326 if (vfc->vfc_vfsops->vfs_uninit != NULL) {
327 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
328 if (error != 0) {
329 vfsconf_unlock();
330 return (error);
331 }
332 }
333 TAILQ_REMOVE(&vfsconf, vfsp, vfc_list);
334 maxtypenum = VFS_GENERIC;
335 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
336 if (maxtypenum < vfsp->vfc_typenum)
337 maxtypenum = vfsp->vfc_typenum;
338 maxvfsconf = maxtypenum + 1;
339 vfsconf_unlock();
340 return (0);
341 }
342
343 /*
344 * Standard kernel module handling code for filesystem modules.
345 * Referenced from VFS_SET().
346 */
347 int
348 vfs_modevent(module_t mod, int type, void *data)
349 {
350 struct vfsconf *vfc;
351 int error = 0;
352
353 vfc = (struct vfsconf *)data;
354
355 switch (type) {
356 case MOD_LOAD:
357 if (vfc)
358 error = vfs_register(vfc);
359 break;
360
361 case MOD_UNLOAD:
362 if (vfc)
363 error = vfs_unregister(vfc);
364 break;
365 default:
366 error = EOPNOTSUPP;
367 break;
368 }
369 return (error);
370 }
Cache object: bee662b379c06336ba343b1d8b55abeb
|