xref: /xnu-8796.101.5/bsd/vfs/vfs_init.c (revision aca3beaa3dfbd42498b42c5e5ce20a938e6554e5)
1 /*
2  * Copyright (c) 2000-2010 Apple Inc. All rights reserved.
3  *
4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5  *
6  * This file contains Original Code and/or Modifications of Original Code
7  * as defined in and that are subject to the Apple Public Source License
8  * Version 2.0 (the 'License'). You may not use this file except in
9  * compliance with the License. The rights granted to you under the License
10  * may not be used to create, or enable the creation or redistribution of,
11  * unlawful or unlicensed copies of an Apple operating system, or to
12  * circumvent, violate, or enable the circumvention or violation of, any
13  * terms of an Apple operating system software license agreement.
14  *
15  * Please obtain a copy of the License at
16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
17  *
18  * The Original Code and all software distributed under the License are
19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23  * Please see the License for the specific language governing rights and
24  * limitations under the License.
25  *
26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27  */
28 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
29 /*
30  * Copyright (c) 1989, 1993
31  *	The Regents of the University of California.  All rights reserved.
32  *
33  * This code is derived from software contributed
34  * to Berkeley by John Heidemann of the UCLA Ficus project.
35  *
36  * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
37  *
38  * Redistribution and use in source and binary forms, with or without
39  * modification, are permitted provided that the following conditions
40  * are met:
41  * 1. Redistributions of source code must retain the above copyright
42  *    notice, this list of conditions and the following disclaimer.
43  * 2. Redistributions in binary form must reproduce the above copyright
44  *    notice, this list of conditions and the following disclaimer in the
45  *    documentation and/or other materials provided with the distribution.
46  * 3. All advertising materials mentioning features or use of this software
47  *    must display the following acknowledgement:
48  *	This product includes software developed by the University of
49  *	California, Berkeley and its contributors.
50  * 4. Neither the name of the University nor the names of its contributors
51  *    may be used to endorse or promote products derived from this software
52  *    without specific prior written permission.
53  *
54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64  * SUCH DAMAGE.
65  *
66  *	@(#)vfs_init.c	8.5 (Berkeley) 5/11/95
67  */
68 /*
69  * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
70  * support for mandatory and extensible security protections.  This notice
71  * is included in support of clause 2.2 (b) of the Apple Public License,
72  * Version 2.0.
73  */
74 
75 
76 #include <sys/param.h>
77 #include <sys/mount_internal.h>
78 #include <sys/time.h>
79 #include <sys/vm.h>
80 #include <sys/vnode_internal.h>
81 #include <sys/stat.h>
82 #include <sys/namei.h>
83 #include <sys/ucred.h>
84 #include <sys/errno.h>
85 #include <kern/kalloc.h>
86 #include <kern/smr.h>
87 #include <sys/decmpfs.h>
88 
89 #if CONFIG_MACF
90 #include <security/mac_framework.h>
91 #include <sys/kauth.h>
92 #endif
93 #if QUOTA
94 #include <sys/quota.h>
95 #endif
96 
97 /*
98  * Sigh, such primitive tools are these...
99  */
100 #if 0
101 #define DODEBUG(A) A
102 #else
103 #define DODEBUG(A)
104 #endif
105 
106 KALLOC_TYPE_DEFINE(mount_zone, struct mount, KT_DEFAULT);
107 
108 SMR_DEFINE(_vfs_smr);
109 const smr_t vfs_smr = &_vfs_smr;
110 
111 __private_extern__ void vntblinit(void);
112 
113 extern const struct vnodeopv_desc *vfs_opv_descs[];
114 /* a list of lists of vnodeops defns */
115 extern struct vnodeop_desc *vfs_op_descs[];
116 /* and the operations they perform */
117 /*
118  * This code doesn't work if the defn is **vnodop_defns with cc.
119  * The problem is because of the compiler sometimes putting in an
120  * extra level of indirection for arrays.  It's an interesting
121  * "feature" of C.
122  */
123 int vfs_opv_numops;
124 
125 typedef int (*PFIvp)(void *);
126 
127 /*
128  * A miscellaneous routine.
129  * A generic "default" routine that just returns an error.
130  */
131 int
vn_default_error(void)132 vn_default_error(void)
133 {
134 	return ENOTSUP;
135 }
136 
137 /*
138  * vfs_init.c
139  *
140  * Allocate and fill in operations vectors.
141  *
142  * An undocumented feature of this approach to defining operations is that
143  * there can be multiple entries in vfs_opv_descs for the same operations
144  * vector. This allows third parties to extend the set of operations
145  * supported by another layer in a binary compatibile way. For example,
146  * assume that NFS needed to be modified to support Ficus. NFS has an entry
147  * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
148  * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
149  * listing those new operations Ficus adds to NFS, all without modifying the
150  * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
151  * that is a(whole)nother story.) This is a feature.
152  */
153 void
vfs_opv_init(void)154 vfs_opv_init(void)
155 {
156 	int i, j, k;
157 	int(***opv_desc_vector_p)(void *);
158 	int(**opv_desc_vector)(void *);
159 	const struct vnodeopv_entry_desc *opve_descp;
160 
161 	/*
162 	 * Allocate the dynamic vectors and fill them in.
163 	 */
164 	for (i = 0; vfs_opv_descs[i]; i++) {
165 		opv_desc_vector_p = vfs_opv_descs[i]->opv_desc_vector_p;
166 		/*
167 		 * Allocate and init the vector, if it needs it.
168 		 * Also handle backwards compatibility.
169 		 */
170 		if (*opv_desc_vector_p == NULL) {
171 			*opv_desc_vector_p = zalloc_permanent(vfs_opv_numops * sizeof(PFIvp),
172 			    ZALIGN(PFIvp));
173 			DODEBUG(printf("vector at %x allocated\n",
174 			    opv_desc_vector_p));
175 		}
176 		opv_desc_vector = *opv_desc_vector_p;
177 		for (j = 0; vfs_opv_descs[i]->opv_desc_ops[j].opve_op; j++) {
178 			opve_descp = &(vfs_opv_descs[i]->opv_desc_ops[j]);
179 
180 			/* Silently skip known-disabled operations */
181 			if (opve_descp->opve_op->vdesc_flags & VDESC_DISABLED) {
182 				printf("vfs_fsadd: Ignoring reference in %p to disabled operation %s.\n",
183 				    vfs_opv_descs[i], opve_descp->opve_op->vdesc_name);
184 				continue;
185 			}
186 
187 			/*
188 			 * Sanity check:  is this operation listed
189 			 * in the list of operations?  We check this
190 			 * by seeing if its offest is zero.  Since
191 			 * the default routine should always be listed
192 			 * first, it should be the only one with a zero
193 			 * offset.  Any other operation with a zero
194 			 * offset is probably not listed in
195 			 * vfs_op_descs, and so is probably an error.
196 			 *
197 			 * A panic here means the layer programmer
198 			 * has committed the all-too common bug
199 			 * of adding a new operation to the layer's
200 			 * list of vnode operations but
201 			 * not adding the operation to the system-wide
202 			 * list of supported operations.
203 			 */
204 			if (opve_descp->opve_op->vdesc_offset == 0 &&
205 			    opve_descp->opve_op !=
206 			    VDESC(vnop_default)) {
207 				printf("operation %s not listed in %s.\n",
208 				    opve_descp->opve_op->vdesc_name,
209 				    "vfs_op_descs");
210 				panic("vfs_opv_init: bad operation");
211 			}
212 			/*
213 			 * Fill in this entry.
214 			 */
215 			opv_desc_vector[opve_descp->opve_op->vdesc_offset] =
216 			    opve_descp->opve_impl;
217 		}
218 	}
219 	/*
220 	 * Finally, go back and replace unfilled routines
221 	 * with their default.  (Sigh, an O(n^3) algorithm.  I
222 	 * could make it better, but that'd be work, and n is small.)
223 	 */
224 	for (i = 0; vfs_opv_descs[i]; i++) {
225 		opv_desc_vector = *(vfs_opv_descs[i]->opv_desc_vector_p);
226 		/*
227 		 * Force every operations vector to have a default routine.
228 		 */
229 		if (opv_desc_vector[VOFFSET(vnop_default)] == NULL) {
230 			panic("vfs_opv_init: operation vector without default routine.");
231 		}
232 		for (k = 0; k < vfs_opv_numops; k++) {
233 			if (opv_desc_vector[k] == NULL) {
234 				opv_desc_vector[k] =
235 				    opv_desc_vector[VOFFSET(vnop_default)];
236 			}
237 		}
238 	}
239 }
240 
241 /*
242  * Initialize known vnode operations vectors.
243  */
244 void
vfs_op_init(void)245 vfs_op_init(void)
246 {
247 	int i;
248 
249 	DODEBUG(printf("Vnode_interface_init.\n"));
250 	/*
251 	 * Set all vnode vectors to a well known value.
252 	 */
253 	for (i = 0; vfs_opv_descs[i]; i++) {
254 		*(vfs_opv_descs[i]->opv_desc_vector_p) = NULL;
255 	}
256 	/*
257 	 * Figure out how many ops there are by counting the table,
258 	 * and assign each its offset.
259 	 */
260 	for (vfs_opv_numops = 0, i = 0; vfs_op_descs[i]; i++) {
261 		/* Silently skip known-disabled operations */
262 		if (vfs_op_descs[i]->vdesc_flags & VDESC_DISABLED) {
263 			continue;
264 		}
265 		vfs_op_descs[i]->vdesc_offset = vfs_opv_numops;
266 		vfs_opv_numops++;
267 	}
268 	DODEBUG(printf("vfs_opv_numops=%d\n", vfs_opv_numops));
269 }
270 
271 /*
272  * Routines having to do with the management of the vnode table.
273  */
274 extern struct vnodeops dead_vnodeops;
275 extern struct vnodeops spec_vnodeops;
276 
277 /* vars for vnode list lock */
278 static LCK_GRP_DECLARE(vnode_list_lck_grp, "vnode list");
279 static LCK_ATTR_DECLARE(vnode_list_lck_attr, 0, 0);
280 static LCK_SPIN_DECLARE_ATTR(vnode_list_spin_lock,
281     &vnode_list_lck_grp, &vnode_list_lck_attr);
282 static LCK_MTX_DECLARE_ATTR(spechash_mtx_lock,
283     &vnode_list_lck_grp, &vnode_list_lck_attr);
284 LCK_MTX_DECLARE_ATTR(pkg_extensions_lck,
285     &vnode_list_lck_grp, &vnode_list_lck_attr);
286 
287 /* vars for mount lock */
288 static LCK_GRP_DECLARE(mnt_lck_grp, "mount");
289 static LCK_ATTR_DECLARE(mnt_lck_attr, 0, 0);
290 
291 /* vars for mount list lock */
292 static LCK_GRP_DECLARE(mnt_list_lck_grp, "mount list");
293 LCK_MTX_DECLARE(mnt_list_mtx_lock, &mnt_list_lck_grp);
294 
295 /*
296  * We want dead_mountp to be a constant pointer, but vfsinit() runs
297  * pretty late, so we'll allocate the dead_mount statically and
298  * statically-initialized dead_mountp.
299  */
300 static struct mount dead_mount_store;
301 struct mount * const dead_mountp = &dead_mount_store;
302 
303 /*
304  * Initialize the vnode structures and initialize each file system type.
305  */
306 void
vfsinit(void)307 vfsinit(void)
308 {
309 	struct vfstable *vfsp;
310 	int i, maxtypenum;
311 	struct mount * mp;
312 
313 	/*
314 	 * Initialize the vnode table
315 	 */
316 	vntblinit();
317 	/*
318 	 * Initialize the filesystem event mechanism.
319 	 */
320 	vfs_event_init();
321 	/*
322 	 * Initialize the vnode name cache
323 	 */
324 	nchinit();
325 
326 	/*
327 	 * Build vnode operation vectors.
328 	 */
329 	vfs_op_init();
330 	vfs_opv_init();   /* finish the job */
331 	/*
332 	 * Initialize each file system type in the static list,
333 	 * until the first NULL ->vfs_vfsops is encountered.
334 	 */
335 	maxtypenum = VT_NON;
336 	for (vfsp = vfsconf, i = 0; i < maxvfsslots; i++, vfsp++) {
337 		struct vfsconf vfsc;
338 		if (vfsp->vfc_vfsops == (struct vfsops *)0) {
339 			break;
340 		}
341 		if (i) {
342 			vfsconf[i - 1].vfc_next = vfsp;
343 		}
344 		if (maxtypenum <= vfsp->vfc_typenum) {
345 			maxtypenum = vfsp->vfc_typenum + 1;
346 		}
347 
348 		bzero(&vfsc, sizeof(struct vfsconf));
349 		vfsc.vfc_reserved1 = 0;
350 		bcopy(vfsp->vfc_name, vfsc.vfc_name, sizeof(vfsc.vfc_name));
351 		vfsc.vfc_typenum = vfsp->vfc_typenum;
352 		vfsc.vfc_refcount = vfsp->vfc_refcount;
353 		vfsc.vfc_flags = vfsp->vfc_flags;
354 		vfsc.vfc_reserved2 = 0;
355 		vfsc.vfc_reserved3 = 0;
356 
357 		if (vfsp->vfc_vfsops->vfs_sysctl) {
358 			struct sysctl_oid *oidp = NULL;
359 			struct sysctl_oid oid = SYSCTL_STRUCT_INIT(_vfs, vfsp->vfc_typenum, , CTLTYPE_NODE | CTLFLAG_KERN | CTLFLAG_RW | CTLFLAG_LOCKED, NULL, 0, vfs_sysctl_node, "-", "");
360 
361 			oidp = kalloc_type(struct sysctl_oid, Z_WAITOK);
362 			*oidp = oid;
363 
364 			/* Memory for VFS oid held by vfsentry forever */
365 			vfsp->vfc_sysctl = oidp;
366 			oidp->oid_name = vfsp->vfc_name;
367 			sysctl_register_oid(vfsp->vfc_sysctl);
368 		}
369 
370 		(*vfsp->vfc_vfsops->vfs_init)(&vfsc);
371 
372 		numused_vfsslots++;
373 		numregistered_fses++;
374 	}
375 	/* next vfc_typenum to be used */
376 	maxvfstypenum = maxtypenum;
377 
378 	/*
379 	 * Initialize the vnop authorization scope.
380 	 */
381 	vnode_authorize_init();
382 
383 	/*
384 	 * create a mount point for dead vnodes
385 	 */
386 	mp = &dead_mount_store;
387 	/* Initialize the default IO constraints */
388 	mp->mnt_maxreadcnt = mp->mnt_maxwritecnt = MAXPHYS;
389 	mp->mnt_segreadcnt = mp->mnt_segwritecnt = 32;
390 	mp->mnt_maxsegreadsize = mp->mnt_maxreadcnt;
391 	mp->mnt_maxsegwritesize = mp->mnt_maxwritecnt;
392 	mp->mnt_devblocksize = DEV_BSIZE;
393 	mp->mnt_alignmentmask = PAGE_MASK;
394 	mp->mnt_ioqueue_depth = MNT_DEFAULT_IOQUEUE_DEPTH;
395 	mp->mnt_ioscale = 1;
396 	mp->mnt_ioflags = 0;
397 	mp->mnt_realrootvp = NULLVP;
398 	mp->mnt_authcache_ttl = CACHED_LOOKUP_RIGHT_TTL;
399 
400 	TAILQ_INIT(&mp->mnt_vnodelist);
401 	TAILQ_INIT(&mp->mnt_workerqueue);
402 	TAILQ_INIT(&mp->mnt_newvnodes);
403 	mp->mnt_flag = MNT_LOCAL;
404 	mp->mnt_lflag = MNT_LDEAD;
405 	mount_lock_init(mp);
406 
407 #if CONFIG_MACF
408 	mac_mount_label_init(mp);
409 	mac_mount_label_associate(vfs_context_kernel(), mp);
410 #endif
411 	/*
412 	 * dead_mountp is a statically-initialized constant pointer
413 	 * to dead_mount_store.
414 	 */
415 
416 #if FS_COMPRESSION
417 	decmpfs_init();
418 #endif
419 
420 	nspace_resolver_init();
421 }
422 
423 void
vnode_list_lock(void)424 vnode_list_lock(void)
425 {
426 	lck_spin_lock_grp(&vnode_list_spin_lock, &vnode_list_lck_grp);
427 }
428 
429 void
vnode_list_unlock(void)430 vnode_list_unlock(void)
431 {
432 	lck_spin_unlock(&vnode_list_spin_lock);
433 }
434 
435 void
mount_list_lock(void)436 mount_list_lock(void)
437 {
438 	lck_mtx_lock(&mnt_list_mtx_lock);
439 }
440 
441 void
mount_list_unlock(void)442 mount_list_unlock(void)
443 {
444 	lck_mtx_unlock(&mnt_list_mtx_lock);
445 }
446 
447 void
mount_lock_init(mount_t mp)448 mount_lock_init(mount_t mp)
449 {
450 	lck_mtx_init(&mp->mnt_mlock, &mnt_lck_grp, &mnt_lck_attr);
451 	lck_mtx_init(&mp->mnt_iter_lock, &mnt_lck_grp, &mnt_lck_attr);
452 	lck_mtx_init(&mp->mnt_renamelock, &mnt_lck_grp, &mnt_lck_attr);
453 	lck_rw_init(&mp->mnt_rwlock, &mnt_lck_grp, &mnt_lck_attr);
454 }
455 
456 void
mount_lock_destroy(mount_t mp)457 mount_lock_destroy(mount_t mp)
458 {
459 	lck_mtx_destroy(&mp->mnt_mlock, &mnt_lck_grp);
460 	lck_mtx_destroy(&mp->mnt_iter_lock, &mnt_lck_grp);
461 	lck_mtx_destroy(&mp->mnt_renamelock, &mnt_lck_grp);
462 	lck_rw_destroy(&mp->mnt_rwlock, &mnt_lck_grp);
463 }
464 
465 
466 /*
467  * Name:	vfstable_add
468  *
469  * Description:	Add a filesystem to the vfsconf list at the first
470  *		unused slot.  If no slots are available, return an
471  *		error.
472  *
473  * Parameter:	nvfsp		vfsconf for VFS to add
474  *
475  * Returns:	0		Success
476  *		-1		Failure
477  *
478  * Notes:	The vfsconf should be treated as a linked list by
479  *		all external references, as the implementation is
480  *		expected to change in the future.  The linkage is
481  *		through ->vfc_next, and the list is NULL terminated.
482  *
483  * Warning:	This code assumes that vfsconf[0] is non-empty.
484  */
485 struct vfstable *
vfstable_add(struct vfstable * nvfsp)486 vfstable_add(struct vfstable  *nvfsp)
487 {
488 	int slot;
489 	struct vfstable *slotp, *allocated = NULL;
490 	struct sysctl_oid *oidp = NULL;
491 
492 
493 	if (nvfsp->vfc_vfsops->vfs_sysctl) {
494 		struct sysctl_oid oid = SYSCTL_STRUCT_INIT(_vfs, nvfsp->vfc_typenum, , CTLTYPE_NODE | CTLFLAG_KERN | CTLFLAG_RW | CTLFLAG_LOCKED, NULL, 0, vfs_sysctl_node, "-", "");
495 
496 		oidp = kalloc_type(struct sysctl_oid, Z_WAITOK);
497 		*oidp = oid;
498 	}
499 
500 	/*
501 	 * Find the next empty slot; we recognize an empty slot by a
502 	 * NULL-valued ->vfc_vfsops, so if we delete a VFS, we must
503 	 * ensure we set the entry back to NULL.
504 	 */
505 findslot:
506 	mount_list_lock();
507 	for (slot = 0; slot < maxvfsslots; slot++) {
508 		if (vfsconf[slot].vfc_vfsops == NULL) {
509 			break;
510 		}
511 	}
512 	if (slot == maxvfsslots) {
513 		if (allocated == NULL) {
514 			mount_list_unlock();
515 			/* out of static slots; allocate one instead */
516 			allocated = kalloc_type(struct vfstable, Z_WAITOK);
517 			goto findslot;
518 		} else {
519 			slotp = allocated;
520 		}
521 	} else {
522 		slotp = &vfsconf[slot];
523 	}
524 
525 	/*
526 	 * Replace the contents of the next empty slot with the contents
527 	 * of the provided nvfsp.
528 	 *
529 	 * Note; Takes advantage of the fact that 'slot' was left
530 	 * with the value of 'maxvfslots' in the allocation case.
531 	 */
532 	bcopy(nvfsp, slotp, sizeof(struct vfstable));
533 	if (slot != 0) {
534 		slotp->vfc_next = vfsconf[slot - 1].vfc_next;
535 		vfsconf[slot - 1].vfc_next = slotp;
536 	} else {
537 		slotp->vfc_next = NULL;
538 	}
539 
540 	if (slotp != allocated) {
541 		/* used a statically allocated slot */
542 		numused_vfsslots++;
543 	}
544 	numregistered_fses++;
545 
546 	if (oidp) {
547 		/* Memory freed in vfstable_del after unregistration */
548 		slotp->vfc_sysctl = oidp;
549 		oidp->oid_name = slotp->vfc_name;
550 		sysctl_register_oid(slotp->vfc_sysctl);
551 	}
552 
553 	mount_list_unlock();
554 
555 	if (allocated && allocated != slotp) {
556 		/* did allocation, but ended up using static slot */
557 		kfree_type(struct vfstable, allocated);
558 	}
559 
560 	return slotp;
561 }
562 
563 /*
564  * Name:	vfstable_del
565  *
566  * Description:	Remove a filesystem from the vfsconf list by name.
567  *		If no such filesystem exists, return an error.
568  *
569  * Parameter:	fs_name		name of VFS to remove
570  *
571  * Returns:	0		Success
572  *		-1		Failure
573  *
574  * Notes:	Hopefully all filesystems have unique names.
575  */
576 int
vfstable_del(struct vfstable * vtbl)577 vfstable_del(struct vfstable  * vtbl)
578 {
579 	struct vfstable **vcpp;
580 	struct vfstable *vcdelp;
581 
582 #if DEBUG
583 	lck_mtx_assert(&mnt_list_mtx_lock, LCK_MTX_ASSERT_OWNED);
584 #endif /* DEBUG */
585 
586 	/*
587 	 * Traverse the list looking for vtbl; if found, *vcpp
588 	 * will contain the address of the pointer to the entry to
589 	 * be removed.
590 	 */
591 	for (vcpp = &vfsconf; *vcpp; vcpp = &(*vcpp)->vfc_next) {
592 		if (*vcpp == vtbl) {
593 			break;
594 		}
595 	}
596 
597 	if (*vcpp == NULL) {
598 		return ESRCH; /* vtbl not on vfsconf list */
599 	}
600 	if ((*vcpp)->vfc_sysctl) {
601 		sysctl_unregister_oid((*vcpp)->vfc_sysctl);
602 		(*vcpp)->vfc_sysctl->oid_name = NULL;
603 		kfree_type(struct sysctl_oid, (*vcpp)->vfc_sysctl);
604 	}
605 
606 	/* Unlink entry */
607 	vcdelp = *vcpp;
608 	*vcpp = (*vcpp)->vfc_next;
609 
610 	/*
611 	 * Is this an entry from our static table?  We find out by
612 	 * seeing if the pointer to the object to be deleted places
613 	 * the object in the address space containing the table (or not).
614 	 */
615 	if (vcdelp >= vfsconf && vcdelp < (vfsconf + maxvfsslots)) {    /* Y */
616 		/* Mark as empty for vfscon_add() */
617 		bzero(vcdelp, sizeof(struct vfstable));
618 		numregistered_fses--;
619 		numused_vfsslots--;
620 	} else {                                                        /* N */
621 		/*
622 		 * This entry was dynamically allocated; we must free it;
623 		 * we would prefer to have just linked the caller's
624 		 * vfsconf onto our list, but it may not be persistent
625 		 * because of the previous (copying) implementation.
626 		 */
627 		numregistered_fses--;
628 		mount_list_unlock();
629 		kfree_type(struct vfstable, vcdelp);
630 		mount_list_lock();
631 	}
632 
633 #if DEBUG
634 	lck_mtx_assert(&mnt_list_mtx_lock, LCK_MTX_ASSERT_OWNED);
635 #endif /* DEBUG */
636 
637 	return 0;
638 }
639 
640 void
SPECHASH_LOCK(void)641 SPECHASH_LOCK(void)
642 {
643 	lck_mtx_lock(&spechash_mtx_lock);
644 }
645 
646 void
SPECHASH_UNLOCK(void)647 SPECHASH_UNLOCK(void)
648 {
649 	lck_mtx_unlock(&spechash_mtx_lock);
650 }
651