devfs_devs.c revision 85979 
1#define DEBUG 1
2/*
3 * Copyright (c) 2000
4 *	Poul-Henning Kamp.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Neither the name of the University nor the names of its contributors
12 *    may be used to endorse or promote products derived from this software
13 *    without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vfsops.c 1.36
28 *
29 * $FreeBSD: head/sys/fs/devfs/devfs_devs.c 85979 2001-11-03 16:53:24Z phk $
30 */
31
32#include "opt_devfs.h"
33#ifndef NODEVFS
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/conf.h>
38#include <sys/dirent.h>
39#include <sys/kernel.h>
40#include <sys/lock.h>
41#include <sys/malloc.h>
42#include <sys/proc.h>
43#include <sys/sysctl.h>
44#include <sys/vnode.h>
45
46#include <machine/atomic.h>
47
48#include <fs/devfs/devfs.h>
49
50static dev_t devfs_inot[NDEVFSINO];
51static dev_t *devfs_overflow;
52static int devfs_ref[NDEVFSINO];
53static int *devfs_refoverflow;
54static int devfs_nextino = 3;
55static int devfs_numino;
56static int devfs_topino;
57static int devfs_noverflowwant = NDEVFSOVERFLOW;
58static int devfs_noverflow;
59static unsigned devfs_generation;
60
61static void devfs_attemptoverflow(int insist);
62static struct devfs_dirent *devfs_find (struct devfs_dirent *dd, const char *name, int namelen);
63
64SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");
65SYSCTL_UINT(_vfs_devfs, OID_AUTO, noverflow, CTLFLAG_RW,
66	&devfs_noverflowwant, 0, "Size of DEVFS overflow table");
67SYSCTL_UINT(_vfs_devfs, OID_AUTO, generation, CTLFLAG_RD,
68	&devfs_generation, 0, "DEVFS generation number");
69SYSCTL_UINT(_vfs_devfs, OID_AUTO, inodes, CTLFLAG_RD,
70	&devfs_numino, 0, "DEVFS inodes");
71SYSCTL_UINT(_vfs_devfs, OID_AUTO, topinode, CTLFLAG_RD,
72	&devfs_topino, 0, "DEVFS highest inode#");
73
74static int *
75devfs_itor(int inode)
76{
77	if (inode < NDEVFSINO)
78		return (&devfs_ref[inode]);
79	else if (inode < NDEVFSINO + devfs_noverflow)
80		return (&devfs_refoverflow[inode - NDEVFSINO]);
81	else
82		panic ("YRK!");
83}
84
85static void
86devfs_dropref(int inode)
87{
88	int *ip;
89
90	ip = devfs_itor(inode);
91	atomic_add_int(ip, -1);
92}
93
94static int
95devfs_getref(int inode)
96{
97	int *ip, i, j;
98	dev_t *dp;
99
100	ip = devfs_itor(inode);
101	dp = devfs_itod(inode);
102	for (;;) {
103		i = *ip;
104		j = i + 1;
105		if (!atomic_cmpset_int(ip, i, j))
106			continue;
107		if (*dp != NULL)
108			return (1);
109		atomic_add_int(ip, -1);
110		return(0);
111	}
112}
113
114struct devfs_dirent **
115devfs_itode (struct devfs_mount *dm, int inode)
116{
117
118	if (inode < NDEVFSINO)
119		return (&dm->dm_dirent[inode]);
120	if (devfs_overflow == NULL)
121		return (NULL);
122	if (inode < NDEVFSINO + devfs_noverflow)
123		return (&dm->dm_overflow[inode - NDEVFSINO]);
124	return (NULL);
125}
126
127dev_t *
128devfs_itod (int inode)
129{
130
131	if (inode < NDEVFSINO)
132		return (&devfs_inot[inode]);
133	if (devfs_overflow == NULL)
134		return (NULL);
135	if (inode < NDEVFSINO + devfs_noverflow)
136		return (&devfs_overflow[inode - NDEVFSINO]);
137	return (NULL);
138}
139
140static void
141devfs_attemptoverflow(int insist)
142{
143	dev_t **ot;
144	int *or;
145	int n, nb;
146
147	/* Check if somebody beat us to it */
148	if (devfs_overflow != NULL)
149		return;
150	ot = NULL;
151	or = NULL;
152	n = devfs_noverflowwant;
153	nb = sizeof (struct dev_t *) * n;
154	MALLOC(ot, dev_t **, nb, M_DEVFS, (insist ? M_WAITOK : M_NOWAIT) | M_ZERO);
155	if (ot == NULL)
156		goto bail;
157	nb = sizeof (int) * n;
158	MALLOC(or, int *, nb, M_DEVFS, (insist ? M_WAITOK : M_NOWAIT) | M_ZERO);
159	if (or == NULL)
160		goto bail;
161	if (!atomic_cmpset_ptr(&devfs_overflow, NULL, ot))
162		goto bail;
163	devfs_refoverflow = or;
164	devfs_noverflow = n;
165	printf("DEVFS Overflow table with %d entries allocated when %d in use\n", n, devfs_numino);
166	return;
167
168bail:
169	/* Somebody beat us to it, or something went wrong. */
170	if (ot != NULL)
171		FREE(ot, M_DEVFS);
172	if (or != NULL)
173		FREE(or, M_DEVFS);
174	return;
175}
176
177static struct devfs_dirent *
178devfs_find(struct devfs_dirent *dd, const char *name, int namelen)
179{
180	struct devfs_dirent *de;
181
182	TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
183		if (namelen != de->de_dirent->d_namlen)
184			continue;
185		if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
186			continue;
187		break;
188	}
189	return (de);
190}
191
192struct devfs_dirent *
193devfs_newdirent(char *name, int namelen)
194{
195	int i;
196	struct devfs_dirent *de;
197	struct dirent d;
198
199	d.d_namlen = namelen;
200	i = sizeof (*de) + GENERIC_DIRSIZ(&d);
201	MALLOC(de, struct devfs_dirent *, i, M_DEVFS, M_WAITOK | M_ZERO);
202	de->de_dirent = (struct dirent *)(de + 1);
203	de->de_dirent->d_namlen = namelen;
204	de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
205	bcopy(name, de->de_dirent->d_name, namelen);
206	de->de_dirent->d_name[namelen] = '\0';
207	vfs_timestamp(&de->de_ctime);
208	de->de_mtime = de->de_atime = de->de_ctime;
209	de->de_links = 1;
210	return (de);
211}
212
213struct devfs_dirent *
214devfs_vmkdir(char *name, int namelen, struct devfs_dirent *dotdot)
215{
216	struct devfs_dirent *dd;
217	struct devfs_dirent *de;
218
219	dd = devfs_newdirent(name, namelen);
220
221	TAILQ_INIT(&dd->de_dlist);
222
223	dd->de_dirent->d_type = DT_DIR;
224	dd->de_mode = 0555;
225	dd->de_links = 2;
226	dd->de_dir = dd;
227
228	de = devfs_newdirent(".", 1);
229	de->de_dirent->d_type = DT_DIR;
230	de->de_dir = dd;
231	de->de_flags |= DE_DOT;
232	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
233
234	de = devfs_newdirent("..", 2);
235	de->de_dirent->d_type = DT_DIR;
236	if (dotdot == NULL)
237		de->de_dir = dd;
238	else
239		de->de_dir = dotdot;
240	de->de_flags |= DE_DOTDOT;
241	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
242
243	return (dd);
244}
245
246static void
247devfs_delete(struct devfs_dirent *dd, struct devfs_dirent *de)
248{
249
250	if (de->de_symlink) {
251		FREE(de->de_symlink, M_DEVFS);
252		de->de_symlink = NULL;
253	}
254	if (de->de_vnode)
255		de->de_vnode->v_data = NULL;
256	TAILQ_REMOVE(&dd->de_dlist, de, de_list);
257	FREE(de, M_DEVFS);
258}
259
260void
261devfs_purge(struct devfs_dirent *dd)
262{
263	struct devfs_dirent *de;
264
265	for (;;) {
266		de = TAILQ_FIRST(&dd->de_dlist);
267		if (de == NULL)
268			break;
269		devfs_delete(dd, de);
270	}
271	FREE(dd, M_DEVFS);
272}
273
274
275int
276devfs_populate(struct devfs_mount *dm)
277{
278	int i, j;
279	dev_t dev, pdev;
280	struct devfs_dirent *dd;
281	struct devfs_dirent *de, **dep;
282	char *q, *s;
283
284	if (dm->dm_generation == devfs_generation)
285		return (0);
286	lockmgr(&dm->dm_lock, LK_UPGRADE, 0, curthread);
287	if (devfs_noverflow && dm->dm_overflow == NULL) {
288		i = devfs_noverflow * sizeof (struct devfs_dirent *);
289		MALLOC(dm->dm_overflow, struct devfs_dirent **, i,
290			M_DEVFS, M_WAITOK | M_ZERO);
291	}
292	while (dm->dm_generation != devfs_generation) {
293		dm->dm_generation = devfs_generation;
294		for (i = 0; i <= devfs_topino; i++) {
295			dev = *devfs_itod(i);
296			dep = devfs_itode(dm, i);
297			de = *dep;
298			if (dev == NULL && de == DE_DELETED) {
299				*dep = NULL;
300				continue;
301			}
302			if (dev == NULL && de != NULL) {
303				dd = de->de_dir;
304				*dep = NULL;
305				TAILQ_REMOVE(&dd->de_dlist, de, de_list);
306				if (de->de_vnode)
307					de->de_vnode->v_data = NULL;
308				FREE(de, M_DEVFS);
309				devfs_dropref(i);
310				continue;
311			}
312			if (dev == NULL)
313				continue;
314			if (de != NULL)
315				continue;
316			if (!devfs_getref(i))
317				continue;
318			dd = dm->dm_basedir;
319			s = dev->si_name;
320			for (;;) {
321				for (q = s; *q != '/' && *q != '\0'; q++)
322					continue;
323				if (*q != '/')
324					break;
325				de = devfs_find(dd, s, q - s);
326				if (de == NULL) {
327					de = devfs_vmkdir(s, q - s, dd);
328					de->de_inode = dm->dm_inode++;
329					TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
330					dd->de_links++;
331				}
332				s = q + 1;
333				dd = de;
334			}
335			de = devfs_newdirent(s, q - s);
336			if (dev->si_flags & SI_ALIAS) {
337				de->de_inode = dm->dm_inode++;
338				de->de_uid = 0;
339				de->de_gid = 0;
340				de->de_mode = 0755;
341				de->de_dirent->d_type = DT_LNK;
342				pdev = dev->si_parent;
343				j = strlen(pdev->si_name) + 1;
344				MALLOC(de->de_symlink, char *, j, M_DEVFS, M_WAITOK);
345				bcopy(pdev->si_name, de->de_symlink, j);
346			} else {
347				de->de_inode = i;
348				de->de_uid = dev->si_uid;
349				de->de_gid = dev->si_gid;
350				de->de_mode = dev->si_mode;
351				de->de_dirent->d_type = DT_CHR;
352			}
353			*dep = de;
354			de->de_dir = dd;
355			TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
356#if 0
357			printf("Add ino%d %s\n", i, dev->si_name);
358#endif
359		}
360	}
361	lockmgr(&dm->dm_lock, LK_DOWNGRADE, 0, curthread);
362	return (0);
363}
364
365static void
366devfs_create(dev_t dev)
367{
368	int ino, i, *ip;
369	dev_t *dp;
370
371	for (;;) {
372		/* Grab the next inode number */
373		ino = devfs_nextino;
374		i = ino + 1;
375		/* wrap around when we reach the end */
376		if (i >= NDEVFSINO + devfs_noverflow)
377			i = 3;
378		if (!atomic_cmpset_int(&devfs_nextino, ino, i))
379			continue;
380
381		/* see if it was occupied */
382		dp = devfs_itod(ino);
383		if (dp == NULL)
384			Debugger("dp == NULL\n");
385		if (*dp != NULL)
386			continue;
387		ip = devfs_itor(ino);
388		if (ip == NULL)
389			Debugger("ip == NULL\n");
390		if (*ip != 0)
391			continue;
392
393		if (!atomic_cmpset_ptr(dp, NULL, dev))
394			continue;
395
396		dev->si_inode = ino;
397		for (;;) {
398			i = devfs_topino;
399			if (i >= ino)
400				break;
401			if (atomic_cmpset_int(&devfs_topino, i, ino))
402				break;
403			printf("failed topino %d %d\n", i, ino);
404		}
405		break;
406	}
407
408	atomic_add_int(&devfs_numino, 1);
409	atomic_add_int(&devfs_generation, 1);
410	if (devfs_overflow == NULL && devfs_numino + 100 > NDEVFSINO)
411		devfs_attemptoverflow(0);
412}
413
414static void
415devfs_destroy(dev_t dev)
416{
417	int ino, i;
418
419	ino = dev->si_inode;
420	dev->si_inode = 0;
421	if (ino == 0)
422		return;
423	if (atomic_cmpset_ptr(devfs_itod(ino), dev, NULL)) {
424		atomic_add_int(&devfs_generation, 1);
425		atomic_add_int(&devfs_numino, -1);
426		i = devfs_nextino;
427		if (ino < i)
428			atomic_cmpset_int(&devfs_nextino, i, ino);
429	}
430}
431
432devfs_create_t *devfs_create_hook = devfs_create;
433devfs_destroy_t *devfs_destroy_hook = devfs_destroy;
434int devfs_present = 1;
435#endif
436