xref: /freebsd/sys/fs/pseudofs/pseudofs.c (revision 2b833162) 
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer
12  *    in this position and unchanged.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. The name of the author may not be used to endorse or promote products
17  *    derived from this software without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33 
34 #include "opt_pseudofs.h"
35 
36 #include <sys/param.h>
37 #include <sys/kernel.h>
38 #include <sys/systm.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/module.h>
42 #include <sys/mount.h>
43 #include <sys/mutex.h>
44 #include <sys/proc.h>
45 #include <sys/sbuf.h>
46 #include <sys/sysctl.h>
47 #include <sys/vnode.h>
48 
49 #include <fs/pseudofs/pseudofs.h>
50 #include <fs/pseudofs/pseudofs_internal.h>
51 
52 static MALLOC_DEFINE(M_PFSNODES, "pfs_nodes", "pseudofs nodes");
53 
54 SYSCTL_NODE(_vfs, OID_AUTO, pfs, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
55     "pseudofs");
56 
57 #ifdef PSEUDOFS_TRACE
58 int pfs_trace;
59 SYSCTL_INT(_vfs_pfs, OID_AUTO, trace, CTLFLAG_RW, &pfs_trace, 0,
60     "enable tracing of pseudofs vnode operations");
61 #endif
62 
63 #if PFS_FSNAMELEN != MFSNAMELEN
64 #error "PFS_FSNAMELEN is not equal to MFSNAMELEN"
65 #endif
66 
67 /*
68  * Allocate and initialize a node
69  */
70 static struct pfs_node *
71 pfs_alloc_node_flags(struct pfs_info *pi, const char *name, pfs_type_t type, int flags)
72 {
73 	struct pfs_node *pn;
74 	int malloc_flags;
75 	size_t len;
76 
77 	len = strlen(name);
78 	KASSERT(len < PFS_NAMELEN,
79 	    ("%s(): node name is too long", __func__));
80 	if (flags & PFS_NOWAIT)
81 		malloc_flags = M_NOWAIT | M_ZERO;
82 	else
83 		malloc_flags = M_WAITOK | M_ZERO;
84 	pn = malloc(sizeof(*pn) + len + 1, M_PFSNODES, malloc_flags);
85 	if (pn == NULL)
86 		return (NULL);
87 	mtx_init(&pn->pn_mutex, "pfs_node", NULL, MTX_DEF | MTX_DUPOK);
88 	memcpy(pn->pn_name, name, len);
89 	pn->pn_type = type;
90 	pn->pn_info = pi;
91 	return (pn);
92 }
93 
94 static struct pfs_node *
95 pfs_alloc_node(struct pfs_info *pi, const char *name, pfs_type_t type)
96 {
97 	return (pfs_alloc_node_flags(pi, name, type, 0));
98 }
99 
100 /*
101  * Add a node to a directory
102  */
103 static void
104 pfs_add_node(struct pfs_node *parent, struct pfs_node *pn)
105 {
106 #ifdef INVARIANTS
107 	struct pfs_node *iter;
108 #endif
109 
110 	KASSERT(parent != NULL,
111 	    ("%s(): parent is NULL", __func__));
112 	KASSERT(pn->pn_parent == NULL,
113 	    ("%s(): node already has a parent", __func__));
114 	KASSERT(parent->pn_info != NULL,
115 	    ("%s(): parent has no pn_info", __func__));
116 	KASSERT(parent->pn_type == pfstype_dir ||
117 	    parent->pn_type == pfstype_procdir ||
118 	    parent->pn_type == pfstype_root,
119 	    ("%s(): parent is not a directory", __func__));
120 
121 #ifdef INVARIANTS
122 	/* XXX no locking! */
123 	if (pn->pn_type == pfstype_procdir)
124 		for (iter = parent; iter != NULL; iter = iter->pn_parent)
125 			KASSERT(iter->pn_type != pfstype_procdir,
126 			    ("%s(): nested process directories", __func__));
127 	for (iter = parent->pn_nodes; iter != NULL; iter = iter->pn_next) {
128 		KASSERT(strcmp(pn->pn_name, iter->pn_name) != 0,
129 		    ("%s(): homonymous siblings", __func__));
130 		if (pn->pn_type == pfstype_procdir)
131 			KASSERT(iter->pn_type != pfstype_procdir,
132 			    ("%s(): sibling process directories", __func__));
133 	}
134 #endif
135 
136 	pn->pn_parent = parent;
137 	pfs_fileno_alloc(pn);
138 
139 	pfs_lock(parent);
140 	if ((parent->pn_flags & PFS_PROCDEP) != 0)
141 		pn->pn_flags |= PFS_PROCDEP;
142 	if (parent->pn_nodes == NULL) {
143 		KASSERT(parent->pn_last_node == NULL,
144 		    ("%s(): pn_last_node not NULL", __func__));
145 		parent->pn_nodes = pn;
146 		parent->pn_last_node = pn;
147 	} else {
148 		KASSERT(parent->pn_last_node != NULL,
149 		    ("%s(): pn_last_node is NULL", __func__));
150 		KASSERT(parent->pn_last_node->pn_next == NULL,
151 		    ("%s(): pn_last_node->pn_next not NULL", __func__));
152 		parent->pn_last_node->pn_next = pn;
153 		parent->pn_last_node = pn;
154 	}
155 	pfs_unlock(parent);
156 }
157 
158 /*
159  * Detach a node from its aprent
160  */
161 static void
162 pfs_detach_node(struct pfs_node *pn)
163 {
164 	struct pfs_node *node, *parent = pn->pn_parent;
165 	struct pfs_node **iter;
166 
167 	KASSERT(parent != NULL, ("%s(): node has no parent", __func__));
168 	KASSERT(parent->pn_info == pn->pn_info,
169 	    ("%s(): parent has different pn_info", __func__));
170 
171 	pfs_lock(parent);
172 	if (pn == parent->pn_last_node) {
173 		if (pn == pn->pn_nodes) {
174 			parent->pn_last_node = NULL;
175 		} else {
176 			for (node = parent->pn_nodes;
177 			    node->pn_next != pn; node = node->pn_next)
178 				continue;
179 			parent->pn_last_node = node;
180 		}
181 	}
182 	iter = &parent->pn_nodes;
183 	while (*iter != NULL) {
184 		if (*iter == pn) {
185 			*iter = pn->pn_next;
186 			break;
187 		}
188 		iter = &(*iter)->pn_next;
189 	}
190 	pn->pn_parent = NULL;
191 	pfs_unlock(parent);
192 }
193 
194 /*
195  * Add . and .. to a directory
196  */
197 static int
198 pfs_fixup_dir_flags(struct pfs_node *parent, int flags)
199 {
200 	struct pfs_node *dot, *dotdot;
201 
202 	dot = pfs_alloc_node_flags(parent->pn_info, ".", pfstype_this, flags);
203 	if (dot == NULL)
204 		return (ENOMEM);
205 	dotdot = pfs_alloc_node_flags(parent->pn_info, "..", pfstype_parent, flags);
206 	if (dotdot == NULL) {
207 		pfs_destroy(dot);
208 		return (ENOMEM);
209 	}
210 	pfs_add_node(parent, dot);
211 	pfs_add_node(parent, dotdot);
212 	return (0);
213 }
214 
215 static void
216 pfs_fixup_dir(struct pfs_node *parent)
217 {
218 
219 	pfs_fixup_dir_flags(parent, 0);
220 }
221 
222 /*
223  * Create a directory
224  */
225 struct pfs_node	*
226 pfs_create_dir(struct pfs_node *parent, const char *name,
227 	       pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
228 	       int flags)
229 {
230 	struct pfs_node *pn;
231 	int rc;
232 
233 	pn = pfs_alloc_node_flags(parent->pn_info, name,
234 			 (flags & PFS_PROCDEP) ? pfstype_procdir : pfstype_dir, flags);
235 	if (pn == NULL)
236 		return (NULL);
237 	pn->pn_attr = attr;
238 	pn->pn_vis = vis;
239 	pn->pn_destroy = destroy;
240 	pn->pn_flags = flags;
241 	pfs_add_node(parent, pn);
242 	rc = pfs_fixup_dir_flags(pn, flags);
243 	if (rc) {
244 		pfs_destroy(pn);
245 		return (NULL);
246 	}
247 	return (pn);
248 }
249 
250 /*
251  * Create a file
252  */
253 struct pfs_node	*
254 pfs_create_file(struct pfs_node *parent, const char *name, pfs_fill_t fill,
255 		pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
256 		int flags)
257 {
258 	struct pfs_node *pn;
259 
260 	pn = pfs_alloc_node_flags(parent->pn_info, name, pfstype_file, flags);
261 	if (pn == NULL)
262 		return (NULL);
263 	pn->pn_fill = fill;
264 	pn->pn_attr = attr;
265 	pn->pn_vis = vis;
266 	pn->pn_destroy = destroy;
267 	pn->pn_flags = flags;
268 	pfs_add_node(parent, pn);
269 
270 	return (pn);
271 }
272 
273 /*
274  * Create a symlink
275  */
276 struct pfs_node	*
277 pfs_create_link(struct pfs_node *parent, const char *name, pfs_fill_t fill,
278 		pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
279 		int flags)
280 {
281 	struct pfs_node *pn;
282 
283 	pn = pfs_alloc_node_flags(parent->pn_info, name, pfstype_symlink, flags);
284 	if (pn == NULL)
285 		return (NULL);
286 	pn->pn_fill = fill;
287 	pn->pn_attr = attr;
288 	pn->pn_vis = vis;
289 	pn->pn_destroy = destroy;
290 	pn->pn_flags = flags;
291 	pfs_add_node(parent, pn);
292 
293 	return (pn);
294 }
295 
296 /*
297  * Locate a node by name
298  */
299 struct pfs_node *
300 pfs_find_node(struct pfs_node *parent, const char *name)
301 {
302 	struct pfs_node *pn;
303 
304 	pfs_lock(parent);
305 	for (pn = parent->pn_nodes; pn != NULL; pn = pn->pn_next)
306 		if (strcmp(pn->pn_name, name) == 0)
307 			break;
308 	pfs_unlock(parent);
309 	return (pn);
310 }
311 
312 /*
313  * Destroy a node and all its descendants.  If the node to be destroyed
314  * has a parent, the parent's mutex must be held.
315  */
316 int
317 pfs_destroy(struct pfs_node *pn)
318 {
319 	struct pfs_node *iter;
320 
321 	KASSERT(pn != NULL,
322 	    ("%s(): node is NULL", __func__));
323 	KASSERT(pn->pn_info != NULL,
324 	    ("%s(): node has no pn_info", __func__));
325 
326 	if (pn->pn_parent)
327 		pfs_detach_node(pn);
328 
329 	/* destroy children */
330 	if (pn->pn_type == pfstype_dir ||
331 	    pn->pn_type == pfstype_procdir ||
332 	    pn->pn_type == pfstype_root) {
333 		pfs_lock(pn);
334 		while (pn->pn_nodes != NULL) {
335 			iter = pn->pn_nodes;
336 			pn->pn_nodes = iter->pn_next;
337 			iter->pn_parent = NULL;
338 			pfs_unlock(pn);
339 			pfs_destroy(iter);
340 			pfs_lock(pn);
341 		}
342 		pfs_unlock(pn);
343 	}
344 
345 	/* revoke vnodes and fileno */
346 	pfs_purge(pn);
347 
348 	/* callback to free any private resources */
349 	if (pn->pn_destroy != NULL)
350 		pn_destroy(pn);
351 
352 	/* destroy the node */
353 	pfs_fileno_free(pn);
354 	mtx_destroy(&pn->pn_mutex);
355 	free(pn, M_PFSNODES);
356 
357 	return (0);
358 }
359 
360 /*
361  * Mount a pseudofs instance
362  */
363 int
364 pfs_mount(struct pfs_info *pi, struct mount *mp)
365 {
366 	struct statfs *sbp;
367 
368 	if (mp->mnt_flag & MNT_UPDATE)
369 		return (EOPNOTSUPP);
370 
371 	MNT_ILOCK(mp);
372 	mp->mnt_flag |= MNT_LOCAL;
373 	mp->mnt_kern_flag |= MNTK_NOMSYNC;
374 	MNT_IUNLOCK(mp);
375 	mp->mnt_data = pi;
376 	vfs_getnewfsid(mp);
377 
378 	sbp = &mp->mnt_stat;
379 	vfs_mountedfrom(mp, pi->pi_name);
380 	sbp->f_bsize = PAGE_SIZE;
381 	sbp->f_iosize = PAGE_SIZE;
382 	sbp->f_blocks = 1;
383 	sbp->f_bfree = 0;
384 	sbp->f_bavail = 0;
385 	sbp->f_files = 1;
386 	sbp->f_ffree = 0;
387 
388 	return (0);
389 }
390 
391 /*
392  * Compatibility shim for old mount(2) system call
393  */
394 int
395 pfs_cmount(struct mntarg *ma, void *data, uint64_t flags)
396 {
397 	int error;
398 
399 	error = kernel_mount(ma, flags);
400 	return (error);
401 }
402 
403 /*
404  * Unmount a pseudofs instance
405  */
406 int
407 pfs_unmount(struct mount *mp, int mntflags)
408 {
409 	int error;
410 
411 	error = vflush(mp, 0, (mntflags & MNT_FORCE) ?  FORCECLOSE : 0,
412 	    curthread);
413 	return (error);
414 }
415 
416 /*
417  * Return a root vnode
418  */
419 int
420 pfs_root(struct mount *mp, int flags, struct vnode **vpp)
421 {
422 	struct pfs_info *pi;
423 
424 	pi = (struct pfs_info *)mp->mnt_data;
425 	return (pfs_vncache_alloc(mp, vpp, pi->pi_root, NO_PID));
426 }
427 
428 /*
429  * Return filesystem stats
430  */
431 int
432 pfs_statfs(struct mount *mp, struct statfs *sbp)
433 {
434 	/* no-op:  always called with mp->mnt_stat */
435 	return (0);
436 }
437 
438 /*
439  * Initialize a pseudofs instance
440  */
441 int
442 pfs_init(struct pfs_info *pi, struct vfsconf *vfc)
443 {
444 	struct pfs_node *root;
445 	int error;
446 
447 	pfs_fileno_init(pi);
448 
449 	/* set up the root directory */
450 	root = pfs_alloc_node(pi, "/", pfstype_root);
451 	pi->pi_root = root;
452 	pfs_fileno_alloc(root);
453 	pfs_fixup_dir(root);
454 
455 	/* construct file hierarchy */
456 	error = (pi->pi_init)(pi, vfc);
457 	if (error) {
458 		pfs_destroy(root);
459 		pi->pi_root = NULL;
460 		return (error);
461 	}
462 
463 	if (bootverbose)
464 		printf("%s registered\n", pi->pi_name);
465 	return (0);
466 }
467 
468 /*
469  * Destroy a pseudofs instance
470  */
471 int
472 pfs_uninit(struct pfs_info *pi, struct vfsconf *vfc)
473 {
474 	int error;
475 
476 	pfs_destroy(pi->pi_root);
477 	pi->pi_root = NULL;
478 	pfs_fileno_uninit(pi);
479 	if (bootverbose)
480 		printf("%s unregistered\n", pi->pi_name);
481 	error = (pi->pi_uninit)(pi, vfc);
482 	return (error);
483 }
484 
485 /*
486  * Handle load / unload events
487  */
488 static int
489 pfs_modevent(module_t mod, int evt, void *arg)
490 {
491 	switch (evt) {
492 	case MOD_LOAD:
493 		pfs_vncache_load();
494 		break;
495 	case MOD_UNLOAD:
496 	case MOD_SHUTDOWN:
497 		pfs_vncache_unload();
498 		break;
499 	default:
500 		return EOPNOTSUPP;
501 		break;
502 	}
503 	return 0;
504 }
505 
506 /*
507  * Module declaration
508  */
509 static moduledata_t pseudofs_data = {
510 	"pseudofs",
511 	pfs_modevent,
512 	NULL
513 };
514 DECLARE_MODULE(pseudofs, pseudofs_data, SI_SUB_EXEC, SI_ORDER_FIRST);
515 MODULE_VERSION(pseudofs, 1);
516