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/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 sysctl_lock();
169 SLIST_FOREACH(oidp, &sysctl__vfs_children, oid_link)
170 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
171 sysctl_unregister_oid(oidp);
172 oidp->oid_number = vfc->vfc_typenum;
173 sysctl_register_oid(oidp);
174 break;
175 }
176 sysctl_unlock();
177
178 /*
179 * Initialise unused ``struct vfsops'' fields, to use
180 * the vfs_std*() functions. Note, we need the mount
181 * and unmount operations, at the least. The check
182 * for vfsops available is just a debugging aid.
183 */
184 KASSERT(vfc->vfc_vfsops != NULL,
185 ("Filesystem %s has no vfsops", vfc->vfc_name));
186 /*
187 * Check the mount and unmount operations.
188 */
189 vfsops = vfc->vfc_vfsops;
190 KASSERT(vfsops->vfs_mount != NULL,
191 ("Filesystem %s has no mount op", vfc->vfc_name));
192 KASSERT(vfsops->vfs_unmount != NULL,
193 ("Filesystem %s has no unmount op", vfc->vfc_name));
194
195 if (vfsops->vfs_root == NULL)
196 /* return file system's root vnode */
197 vfsops->vfs_root = vfs_stdroot;
198 if (vfsops->vfs_quotactl == NULL)
199 /* quota control */
200 vfsops->vfs_quotactl = vfs_stdquotactl;
201 if (vfsops->vfs_statfs == NULL)
202 /* return file system's status */
203 vfsops->vfs_statfs = vfs_stdstatfs;
204 if (vfsops->vfs_sync == NULL)
205 /*
206 * flush unwritten data (nosync)
207 * file systems can use vfs_stdsync
208 * explicitly by setting it in the
209 * vfsop vector.
210 */
211 vfsops->vfs_sync = vfs_stdnosync;
212 if (vfsops->vfs_vget == NULL)
213 /* convert an inode number to a vnode */
214 vfsops->vfs_vget = vfs_stdvget;
215 if (vfsops->vfs_fhtovp == NULL)
216 /* turn an NFS file handle into a vnode */
217 vfsops->vfs_fhtovp = vfs_stdfhtovp;
218 if (vfsops->vfs_checkexp == NULL)
219 /* check if file system is exported */
220 vfsops->vfs_checkexp = vfs_stdcheckexp;
221 if (vfsops->vfs_init == NULL)
222 /* file system specific initialisation */
223 vfsops->vfs_init = vfs_stdinit;
224 if (vfsops->vfs_uninit == NULL)
225 /* file system specific uninitialisation */
226 vfsops->vfs_uninit = vfs_stduninit;
227 if (vfsops->vfs_extattrctl == NULL)
228 /* extended attribute control */
229 vfsops->vfs_extattrctl = vfs_stdextattrctl;
230 if (vfsops->vfs_sysctl == NULL)
231 vfsops->vfs_sysctl = vfs_stdsysctl;
232
233 /*
234 * Call init function for this VFS...
235 */
236 (*(vfc->vfc_vfsops->vfs_init))(vfc);
237
238 return 0;
239 }
240
241
242 /* Remove registration of a filesystem type */
243 static int
244 vfs_unregister(struct vfsconf *vfc)
245 {
246 struct vfsconf *vfsp;
247 int error, i, maxtypenum;
248
249 i = vfc->vfc_typenum;
250
251 vfsp = vfs_byname(vfc->vfc_name);
252 if (vfsp == NULL)
253 return EINVAL;
254 if (vfsp->vfc_refcount)
255 return EBUSY;
256 if (vfc->vfc_vfsops->vfs_uninit != NULL) {
257 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
258 if (error)
259 return (error);
260 }
261 TAILQ_REMOVE(&vfsconf, vfsp, vfc_list);
262 maxtypenum = VFS_GENERIC;
263 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
264 if (maxtypenum < vfsp->vfc_typenum)
265 maxtypenum = vfsp->vfc_typenum;
266 maxvfsconf = maxtypenum + 1;
267 return 0;
268 }
269
270 /*
271 * Standard kernel module handling code for filesystem modules.
272 * Referenced from VFS_SET().
273 */
274 int
275 vfs_modevent(module_t mod, int type, void *data)
276 {
277 struct vfsconf *vfc;
278 int error = 0;
279
280 vfc = (struct vfsconf *)data;
281
282 switch (type) {
283 case MOD_LOAD:
284 if (vfc)
285 error = vfs_register(vfc);
286 break;
287
288 case MOD_UNLOAD:
289 if (vfc)
290 error = vfs_unregister(vfc);
291 break;
292 default:
293 error = EOPNOTSUPP;
294 break;
295 }
296 return (error);
297 }
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