xref: /freebsd/sys/fs/pseudofs/pseudofs.c (revision 62cfcf62f627e5093fb37026a6d8c98e4d2ef04c) 
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 
76 	KASSERT(strlen(name) < PFS_NAMELEN,
77 	    ("%s(): node name is too long", __func__));
78 	if (flags & PFS_NOWAIT)
79 		malloc_flags = M_NOWAIT | M_ZERO;
80 	else
81 		malloc_flags = M_WAITOK | M_ZERO;
82 	pn = malloc(sizeof *pn, M_PFSNODES, malloc_flags);
83 	if (pn == NULL)
84 		return (NULL);
85 	mtx_init(&pn->pn_mutex, "pfs_node", NULL, MTX_DEF | MTX_DUPOK);
86 	strlcpy(pn->pn_name, name, sizeof pn->pn_name);
87 	pn->pn_type = type;
88 	pn->pn_info = pi;
89 	return (pn);
90 }
91 
92 static struct pfs_node *
93 pfs_alloc_node(struct pfs_info *pi, const char *name, pfs_type_t type)
94 {
95 	return (pfs_alloc_node_flags(pi, name, type, 0));
96 }
97 
98 /*
99  * Add a node to a directory
100  */
101 static void
102 pfs_add_node(struct pfs_node *parent, struct pfs_node *pn)
103 {
104 #ifdef INVARIANTS
105 	struct pfs_node *iter;
106 #endif
107 
108 	KASSERT(parent != NULL,
109 	    ("%s(): parent is NULL", __func__));
110 	KASSERT(pn->pn_parent == NULL,
111 	    ("%s(): node already has a parent", __func__));
112 	KASSERT(parent->pn_info != NULL,
113 	    ("%s(): parent has no pn_info", __func__));
114 	KASSERT(parent->pn_type == pfstype_dir ||
115 	    parent->pn_type == pfstype_procdir ||
116 	    parent->pn_type == pfstype_root,
117 	    ("%s(): parent is not a directory", __func__));
118 
119 #ifdef INVARIANTS
120 	/* XXX no locking! */
121 	if (pn->pn_type == pfstype_procdir)
122 		for (iter = parent; iter != NULL; iter = iter->pn_parent)
123 			KASSERT(iter->pn_type != pfstype_procdir,
124 			    ("%s(): nested process directories", __func__));
125 	for (iter = parent->pn_nodes; iter != NULL; iter = iter->pn_next) {
126 		KASSERT(strcmp(pn->pn_name, iter->pn_name) != 0,
127 		    ("%s(): homonymous siblings", __func__));
128 		if (pn->pn_type == pfstype_procdir)
129 			KASSERT(iter->pn_type != pfstype_procdir,
130 			    ("%s(): sibling process directories", __func__));
131 	}
132 #endif
133 
134 	pn->pn_parent = parent;
135 	pfs_fileno_alloc(pn);
136 
137 	pfs_lock(parent);
138 	if ((parent->pn_flags & PFS_PROCDEP) != 0)
139 		pn->pn_flags |= PFS_PROCDEP;
140 	if (parent->pn_nodes == NULL) {
141 		KASSERT(parent->pn_last_node == NULL,
142 		    ("%s(): pn_last_node not NULL", __func__));
143 		parent->pn_nodes = pn;
144 		parent->pn_last_node = pn;
145 	} else {
146 		KASSERT(parent->pn_last_node != NULL,
147 		    ("%s(): pn_last_node is NULL", __func__));
148 		KASSERT(parent->pn_last_node->pn_next == NULL,
149 		    ("%s(): pn_last_node->pn_next not NULL", __func__));
150 		parent->pn_last_node->pn_next = pn;
151 		parent->pn_last_node = pn;
152 	}
153 	pfs_unlock(parent);
154 }
155 
156 /*
157  * Detach a node from its aprent
158  */
159 static void
160 pfs_detach_node(struct pfs_node *pn)
161 {
162 	struct pfs_node *node, *parent = pn->pn_parent;
163 	struct pfs_node **iter;
164 
165 	KASSERT(parent != NULL, ("%s(): node has no parent", __func__));
166 	KASSERT(parent->pn_info == pn->pn_info,
167 	    ("%s(): parent has different pn_info", __func__));
168 
169 	pfs_lock(parent);
170 	if (pn == parent->pn_last_node) {
171 		if (pn == pn->pn_nodes) {
172 			parent->pn_last_node = NULL;
173 		} else {
174 			for (node = parent->pn_nodes;
175 			    node->pn_next != pn; node = node->pn_next)
176 				continue;
177 			parent->pn_last_node = node;
178 		}
179 	}
180 	iter = &parent->pn_nodes;
181 	while (*iter != NULL) {
182 		if (*iter == pn) {
183 			*iter = pn->pn_next;
184 			break;
185 		}
186 		iter = &(*iter)->pn_next;
187 	}
188 	pn->pn_parent = NULL;
189 	pfs_unlock(parent);
190 }
191 
192 /*
193  * Add . and .. to a directory
194  */
195 static int
196 pfs_fixup_dir_flags(struct pfs_node *parent, int flags)
197 {
198 	struct pfs_node *dot, *dotdot;
199 
200 	dot = pfs_alloc_node_flags(parent->pn_info, ".", pfstype_this, flags);
201 	if (dot == NULL)
202 		return (ENOMEM);
203 	dotdot = pfs_alloc_node_flags(parent->pn_info, "..", pfstype_parent, flags);
204 	if (dotdot == NULL) {
205 		pfs_destroy(dot);
206 		return (ENOMEM);
207 	}
208 	pfs_add_node(parent, dot);
209 	pfs_add_node(parent, dotdot);
210 	return (0);
211 }
212 
213 static void
214 pfs_fixup_dir(struct pfs_node *parent)
215 {
216 
217 	pfs_fixup_dir_flags(parent, 0);
218 }
219 
220 /*
221  * Create a directory
222  */
223 struct pfs_node	*
224 pfs_create_dir(struct pfs_node *parent, const char *name,
225 	       pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
226 	       int flags)
227 {
228 	struct pfs_node *pn;
229 	int rc;
230 
231 	pn = pfs_alloc_node_flags(parent->pn_info, name,
232 			 (flags & PFS_PROCDEP) ? pfstype_procdir : pfstype_dir, flags);
233 	if (pn == NULL)
234 		return (NULL);
235 	pn->pn_attr = attr;
236 	pn->pn_vis = vis;
237 	pn->pn_destroy = destroy;
238 	pn->pn_flags = flags;
239 	pfs_add_node(parent, pn);
240 	rc = pfs_fixup_dir_flags(pn, flags);
241 	if (rc) {
242 		pfs_destroy(pn);
243 		return (NULL);
244 	}
245 	return (pn);
246 }
247 
248 /*
249  * Create a file
250  */
251 struct pfs_node	*
252 pfs_create_file(struct pfs_node *parent, const char *name, pfs_fill_t fill,
253 		pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
254 		int flags)
255 {
256 	struct pfs_node *pn;
257 
258 	pn = pfs_alloc_node_flags(parent->pn_info, name, pfstype_file, flags);
259 	if (pn == NULL)
260 		return (NULL);
261 	pn->pn_fill = fill;
262 	pn->pn_attr = attr;
263 	pn->pn_vis = vis;
264 	pn->pn_destroy = destroy;
265 	pn->pn_flags = flags;
266 	pfs_add_node(parent, pn);
267 
268 	return (pn);
269 }
270 
271 /*
272  * Create a symlink
273  */
274 struct pfs_node	*
275 pfs_create_link(struct pfs_node *parent, const char *name, pfs_fill_t fill,
276 		pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
277 		int flags)
278 {
279 	struct pfs_node *pn;
280 
281 	pn = pfs_alloc_node_flags(parent->pn_info, name, pfstype_symlink, flags);
282 	if (pn == NULL)
283 		return (NULL);
284 	pn->pn_fill = fill;
285 	pn->pn_attr = attr;
286 	pn->pn_vis = vis;
287 	pn->pn_destroy = destroy;
288 	pn->pn_flags = flags;
289 	pfs_add_node(parent, pn);
290 
291 	return (pn);
292 }
293 
294 /*
295  * Locate a node by name
296  */
297 struct pfs_node *
298 pfs_find_node(struct pfs_node *parent, const char *name)
299 {
300 	struct pfs_node *pn;
301 
302 	pfs_lock(parent);
303 	for (pn = parent->pn_nodes; pn != NULL; pn = pn->pn_next)
304 		if (strcmp(pn->pn_name, name) == 0)
305 			break;
306 	pfs_unlock(parent);
307 	return (pn);
308 }
309 
310 /*
311  * Destroy a node and all its descendants.  If the node to be destroyed
312  * has a parent, the parent's mutex must be held.
313  */
314 int
315 pfs_destroy(struct pfs_node *pn)
316 {
317 	struct pfs_node *iter;
318 
319 	KASSERT(pn != NULL,
320 	    ("%s(): node is NULL", __func__));
321 	KASSERT(pn->pn_info != NULL,
322 	    ("%s(): node has no pn_info", __func__));
323 
324 	if (pn->pn_parent)
325 		pfs_detach_node(pn);
326 
327 	/* destroy children */
328 	if (pn->pn_type == pfstype_dir ||
329 	    pn->pn_type == pfstype_procdir ||
330 	    pn->pn_type == pfstype_root) {
331 		pfs_lock(pn);
332 		while (pn->pn_nodes != NULL) {
333 			iter = pn->pn_nodes;
334 			pn->pn_nodes = iter->pn_next;
335 			iter->pn_parent = NULL;
336 			pfs_unlock(pn);
337 			pfs_destroy(iter);
338 			pfs_lock(pn);
339 		}
340 		pfs_unlock(pn);
341 	}
342 
343 	/* revoke vnodes and fileno */
344 	pfs_purge(pn);
345 
346 	/* callback to free any private resources */
347 	if (pn->pn_destroy != NULL)
348 		pn_destroy(pn);
349 
350 	/* destroy the node */
351 	pfs_fileno_free(pn);
352 	mtx_destroy(&pn->pn_mutex);
353 	free(pn, M_PFSNODES);
354 
355 	return (0);
356 }
357 
358 /*
359  * Mount a pseudofs instance
360  */
361 int
362 pfs_mount(struct pfs_info *pi, struct mount *mp)
363 {
364 	struct statfs *sbp;
365 
366 	if (mp->mnt_flag & MNT_UPDATE)
367 		return (EOPNOTSUPP);
368 
369 	MNT_ILOCK(mp);
370 	mp->mnt_flag |= MNT_LOCAL;
371 	mp->mnt_kern_flag |= MNTK_NOMSYNC;
372 	MNT_IUNLOCK(mp);
373 	mp->mnt_data = pi;
374 	vfs_getnewfsid(mp);
375 
376 	sbp = &mp->mnt_stat;
377 	vfs_mountedfrom(mp, pi->pi_name);
378 	sbp->f_bsize = PAGE_SIZE;
379 	sbp->f_iosize = PAGE_SIZE;
380 	sbp->f_blocks = 1;
381 	sbp->f_bfree = 0;
382 	sbp->f_bavail = 0;
383 	sbp->f_files = 1;
384 	sbp->f_ffree = 0;
385 
386 	return (0);
387 }
388 
389 /*
390  * Compatibility shim for old mount(2) system call
391  */
392 int
393 pfs_cmount(struct mntarg *ma, void *data, uint64_t flags)
394 {
395 	int error;
396 
397 	error = kernel_mount(ma, flags);
398 	return (error);
399 }
400 
401 /*
402  * Unmount a pseudofs instance
403  */
404 int
405 pfs_unmount(struct mount *mp, int mntflags)
406 {
407 	int error;
408 
409 	error = vflush(mp, 0, (mntflags & MNT_FORCE) ?  FORCECLOSE : 0,
410 	    curthread);
411 	return (error);
412 }
413 
414 /*
415  * Return a root vnode
416  */
417 int
418 pfs_root(struct mount *mp, int flags, struct vnode **vpp)
419 {
420 	struct pfs_info *pi;
421 
422 	pi = (struct pfs_info *)mp->mnt_data;
423 	return (pfs_vncache_alloc(mp, vpp, pi->pi_root, NO_PID));
424 }
425 
426 /*
427  * Return filesystem stats
428  */
429 int
430 pfs_statfs(struct mount *mp, struct statfs *sbp)
431 {
432 	/* no-op:  always called with mp->mnt_stat */
433 	return (0);
434 }
435 
436 /*
437  * Initialize a pseudofs instance
438  */
439 int
440 pfs_init(struct pfs_info *pi, struct vfsconf *vfc)
441 {
442 	struct pfs_node *root;
443 	int error;
444 
445 	pfs_fileno_init(pi);
446 
447 	/* set up the root directory */
448 	root = pfs_alloc_node(pi, "/", pfstype_root);
449 	pi->pi_root = root;
450 	pfs_fileno_alloc(root);
451 	pfs_fixup_dir(root);
452 
453 	/* construct file hierarchy */
454 	error = (pi->pi_init)(pi, vfc);
455 	if (error) {
456 		pfs_destroy(root);
457 		pi->pi_root = NULL;
458 		return (error);
459 	}
460 
461 	if (bootverbose)
462 		printf("%s registered\n", pi->pi_name);
463 	return (0);
464 }
465 
466 /*
467  * Destroy a pseudofs instance
468  */
469 int
470 pfs_uninit(struct pfs_info *pi, struct vfsconf *vfc)
471 {
472 	int error;
473 
474 	pfs_destroy(pi->pi_root);
475 	pi->pi_root = NULL;
476 	pfs_fileno_uninit(pi);
477 	if (bootverbose)
478 		printf("%s unregistered\n", pi->pi_name);
479 	error = (pi->pi_uninit)(pi, vfc);
480 	return (error);
481 }
482 
483 /*
484  * Handle load / unload events
485  */
486 static int
487 pfs_modevent(module_t mod, int evt, void *arg)
488 {
489 	switch (evt) {
490 	case MOD_LOAD:
491 		pfs_vncache_load();
492 		break;
493 	case MOD_UNLOAD:
494 	case MOD_SHUTDOWN:
495 		pfs_vncache_unload();
496 		break;
497 	default:
498 		return EOPNOTSUPP;
499 		break;
500 	}
501 	return 0;
502 }
503 
504 /*
505  * Module declaration
506  */
507 static moduledata_t pseudofs_data = {
508 	"pseudofs",
509 	pfs_modevent,
510 	NULL
511 };
512 DECLARE_MODULE(pseudofs, pseudofs_data, SI_SUB_EXEC, SI_ORDER_FIRST);
513 MODULE_VERSION(pseudofs, 1);
514