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305136ba74b64109812cd297085f97a5e136053f
[deliverable/linux.git] / fs / autofs4 / root.c
1 /* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/root.c
4 *
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
7 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
8 *
9 * This file is part of the Linux kernel and is made available under
10 * the terms of the GNU General Public License, version 2, or at your
11 * option, any later version, incorporated herein by reference.
12 *
13 * ------------------------------------------------------------------------- */
14
15 #include <linux/capability.h>
16 #include <linux/errno.h>
17 #include <linux/stat.h>
18 #include <linux/param.h>
19 #include <linux/time.h>
20 #include "autofs_i.h"
21
22 static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
23 static int autofs4_dir_unlink(struct inode *,struct dentry *);
24 static int autofs4_dir_rmdir(struct inode *,struct dentry *);
25 static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
26 static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
27 static int autofs4_dir_open(struct inode *inode, struct file *file);
28 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
29 static void *autofs4_follow_link(struct dentry *, struct nameidata *);
30
31 #define TRIGGER_FLAGS (LOOKUP_CONTINUE | LOOKUP_DIRECTORY)
32 #define TRIGGER_INTENTS (LOOKUP_OPEN | LOOKUP_CREATE)
33
34 const struct file_operations autofs4_root_operations = {
35 .open = dcache_dir_open,
36 .release = dcache_dir_close,
37 .read = generic_read_dir,
38 .readdir = dcache_readdir,
39 .llseek = dcache_dir_lseek,
40 .ioctl = autofs4_root_ioctl,
41 };
42
43 const struct file_operations autofs4_dir_operations = {
44 .open = autofs4_dir_open,
45 .release = dcache_dir_close,
46 .read = generic_read_dir,
47 .readdir = dcache_readdir,
48 .llseek = dcache_dir_lseek,
49 };
50
51 const struct inode_operations autofs4_indirect_root_inode_operations = {
52 .lookup = autofs4_lookup,
53 .unlink = autofs4_dir_unlink,
54 .symlink = autofs4_dir_symlink,
55 .mkdir = autofs4_dir_mkdir,
56 .rmdir = autofs4_dir_rmdir,
57 };
58
59 const struct inode_operations autofs4_direct_root_inode_operations = {
60 .lookup = autofs4_lookup,
61 .unlink = autofs4_dir_unlink,
62 .mkdir = autofs4_dir_mkdir,
63 .rmdir = autofs4_dir_rmdir,
64 .follow_link = autofs4_follow_link,
65 };
66
67 const struct inode_operations autofs4_dir_inode_operations = {
68 .lookup = autofs4_lookup,
69 .unlink = autofs4_dir_unlink,
70 .symlink = autofs4_dir_symlink,
71 .mkdir = autofs4_dir_mkdir,
72 .rmdir = autofs4_dir_rmdir,
73 };
74
75 static void autofs4_add_active(struct dentry *dentry)
76 {
77 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
78 struct autofs_info *ino = autofs4_dentry_ino(dentry);
79 if (ino) {
80 spin_lock(&sbi->lookup_lock);
81 if (!ino->active_count) {
82 if (list_empty(&ino->active))
83 list_add(&ino->active, &sbi->active_list);
84 }
85 ino->active_count++;
86 spin_unlock(&sbi->lookup_lock);
87 }
88 return;
89 }
90
91 static void autofs4_del_active(struct dentry *dentry)
92 {
93 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
94 struct autofs_info *ino = autofs4_dentry_ino(dentry);
95 if (ino) {
96 spin_lock(&sbi->lookup_lock);
97 ino->active_count--;
98 if (!ino->active_count) {
99 if (!list_empty(&ino->active))
100 list_del_init(&ino->active);
101 }
102 spin_unlock(&sbi->lookup_lock);
103 }
104 return;
105 }
106
107 static unsigned int autofs4_need_mount(unsigned int flags)
108 {
109 unsigned int res = 0;
110 if (flags & (TRIGGER_FLAGS | TRIGGER_INTENTS))
111 res = 1;
112 return res;
113 }
114
115 static int autofs4_dir_open(struct inode *inode, struct file *file)
116 {
117 struct dentry *dentry = file->f_path.dentry;
118 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
119
120 DPRINTK("file=%p dentry=%p %.*s",
121 file, dentry, dentry->d_name.len, dentry->d_name.name);
122
123 if (autofs4_oz_mode(sbi))
124 goto out;
125
126 /*
127 * An empty directory in an autofs file system is always a
128 * mount point. The daemon must have failed to mount this
129 * during lookup so it doesn't exist. This can happen, for
130 * example, if user space returns an incorrect status for a
131 * mount request. Otherwise we're doing a readdir on the
132 * autofs file system so just let the libfs routines handle
133 * it.
134 */
135 spin_lock(&dcache_lock);
136 if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
137 spin_unlock(&dcache_lock);
138 return -ENOENT;
139 }
140 spin_unlock(&dcache_lock);
141
142 out:
143 return dcache_dir_open(inode, file);
144 }
145
146 static int try_to_fill_dentry(struct dentry *dentry, int flags)
147 {
148 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
149 struct autofs_info *ino = autofs4_dentry_ino(dentry);
150 int status;
151
152 DPRINTK("dentry=%p %.*s ino=%p",
153 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
154
155 /*
156 * Wait for a pending mount, triggering one if there
157 * isn't one already
158 */
159 if (dentry->d_inode == NULL) {
160 DPRINTK("waiting for mount name=%.*s",
161 dentry->d_name.len, dentry->d_name.name);
162
163 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
164
165 DPRINTK("mount done status=%d", status);
166
167 /* Turn this into a real negative dentry? */
168 if (status == -ENOENT) {
169 spin_lock(&sbi->fs_lock);
170 ino->flags &= ~AUTOFS_INF_PENDING;
171 spin_unlock(&sbi->fs_lock);
172 return status;
173 } else if (status) {
174 /* Return a negative dentry, but leave it "pending" */
175 return status;
176 }
177 /* Trigger mount for path component or follow link */
178 } else if (ino->flags & AUTOFS_INF_PENDING ||
179 autofs4_need_mount(flags) ||
180 current->link_count) {
181 DPRINTK("waiting for mount name=%.*s",
182 dentry->d_name.len, dentry->d_name.name);
183
184 spin_lock(&sbi->fs_lock);
185 ino->flags |= AUTOFS_INF_PENDING;
186 spin_unlock(&sbi->fs_lock);
187 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
188
189 DPRINTK("mount done status=%d", status);
190
191 if (status) {
192 spin_lock(&sbi->fs_lock);
193 ino->flags &= ~AUTOFS_INF_PENDING;
194 spin_unlock(&sbi->fs_lock);
195 return status;
196 }
197 }
198
199 /* Initialize expiry counter after successful mount */
200 if (ino)
201 ino->last_used = jiffies;
202
203 spin_lock(&sbi->fs_lock);
204 ino->flags &= ~AUTOFS_INF_PENDING;
205 spin_unlock(&sbi->fs_lock);
206
207 return 0;
208 }
209
210 /* For autofs direct mounts the follow link triggers the mount */
211 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
212 {
213 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
214 struct autofs_info *ino = autofs4_dentry_ino(dentry);
215 int oz_mode = autofs4_oz_mode(sbi);
216 unsigned int lookup_type;
217 int status;
218
219 DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
220 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
221 nd->flags);
222 /*
223 * For an expire of a covered direct or offset mount we need
224 * to break out of follow_down() at the autofs mount trigger
225 * (d_mounted--), so we can see the expiring flag, and manage
226 * the blocking and following here until the expire is completed.
227 */
228 if (oz_mode) {
229 spin_lock(&sbi->fs_lock);
230 if (ino->flags & AUTOFS_INF_EXPIRING) {
231 spin_unlock(&sbi->fs_lock);
232 /* Follow down to our covering mount. */
233 if (!follow_down(&nd->path))
234 goto done;
235 goto follow;
236 }
237 spin_unlock(&sbi->fs_lock);
238 goto done;
239 }
240
241 /* If an expire request is pending everyone must wait. */
242 autofs4_expire_wait(dentry);
243
244 /* We trigger a mount for almost all flags */
245 lookup_type = autofs4_need_mount(nd->flags);
246 spin_lock(&sbi->fs_lock);
247 spin_lock(&dcache_lock);
248 if (!(lookup_type || ino->flags & AUTOFS_INF_PENDING)) {
249 spin_unlock(&dcache_lock);
250 spin_unlock(&sbi->fs_lock);
251 goto follow;
252 }
253
254 /*
255 * If the dentry contains directories then it is an autofs
256 * multi-mount with no root mount offset. So don't try to
257 * mount it again.
258 */
259 if (ino->flags & AUTOFS_INF_PENDING ||
260 (!d_mountpoint(dentry) && __simple_empty(dentry))) {
261 spin_unlock(&dcache_lock);
262 spin_unlock(&sbi->fs_lock);
263
264 status = try_to_fill_dentry(dentry, 0);
265 if (status)
266 goto out_error;
267
268 goto follow;
269 }
270 spin_unlock(&dcache_lock);
271 spin_unlock(&sbi->fs_lock);
272 follow:
273 /*
274 * If there is no root mount it must be an autofs
275 * multi-mount with no root offset so we don't need
276 * to follow it.
277 */
278 if (d_mountpoint(dentry)) {
279 if (!autofs4_follow_mount(&nd->path)) {
280 status = -ENOENT;
281 goto out_error;
282 }
283 }
284
285 done:
286 return NULL;
287
288 out_error:
289 path_put(&nd->path);
290 return ERR_PTR(status);
291 }
292
293 /*
294 * Revalidate is called on every cache lookup. Some of those
295 * cache lookups may actually happen while the dentry is not
296 * yet completely filled in, and revalidate has to delay such
297 * lookups..
298 */
299 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
300 {
301 struct inode *dir = dentry->d_parent->d_inode;
302 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
303 int oz_mode = autofs4_oz_mode(sbi);
304 int flags = nd ? nd->flags : 0;
305 int status = 1;
306
307 /* Pending dentry */
308 spin_lock(&sbi->fs_lock);
309 if (autofs4_ispending(dentry)) {
310 /* The daemon never causes a mount to trigger */
311 spin_unlock(&sbi->fs_lock);
312
313 if (oz_mode)
314 return 1;
315
316 /*
317 * If the directory has gone away due to an expire
318 * we have been called as ->d_revalidate() and so
319 * we need to return false and proceed to ->lookup().
320 */
321 if (autofs4_expire_wait(dentry) == -EAGAIN)
322 return 0;
323
324 /*
325 * A zero status is success otherwise we have a
326 * negative error code.
327 */
328 status = try_to_fill_dentry(dentry, flags);
329 if (status == 0)
330 return 1;
331
332 return status;
333 }
334 spin_unlock(&sbi->fs_lock);
335
336 /* Negative dentry.. invalidate if "old" */
337 if (dentry->d_inode == NULL)
338 return 0;
339
340 /* Check for a non-mountpoint directory with no contents */
341 spin_lock(&dcache_lock);
342 if (S_ISDIR(dentry->d_inode->i_mode) &&
343 !d_mountpoint(dentry) &&
344 __simple_empty(dentry)) {
345 DPRINTK("dentry=%p %.*s, emptydir",
346 dentry, dentry->d_name.len, dentry->d_name.name);
347 spin_unlock(&dcache_lock);
348
349 /* The daemon never causes a mount to trigger */
350 if (oz_mode)
351 return 1;
352
353 /*
354 * A zero status is success otherwise we have a
355 * negative error code.
356 */
357 status = try_to_fill_dentry(dentry, flags);
358 if (status == 0)
359 return 1;
360
361 return status;
362 }
363 spin_unlock(&dcache_lock);
364
365 return 1;
366 }
367
368 void autofs4_dentry_release(struct dentry *de)
369 {
370 struct autofs_info *inf;
371
372 DPRINTK("releasing %p", de);
373
374 inf = autofs4_dentry_ino(de);
375 de->d_fsdata = NULL;
376
377 if (inf) {
378 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
379
380 if (sbi) {
381 spin_lock(&sbi->lookup_lock);
382 if (!list_empty(&inf->active))
383 list_del(&inf->active);
384 if (!list_empty(&inf->expiring))
385 list_del(&inf->expiring);
386 spin_unlock(&sbi->lookup_lock);
387 }
388
389 inf->dentry = NULL;
390 inf->inode = NULL;
391
392 autofs4_free_ino(inf);
393 }
394 }
395
396 /* For dentries of directories in the root dir */
397 static const struct dentry_operations autofs4_root_dentry_operations = {
398 .d_revalidate = autofs4_revalidate,
399 .d_release = autofs4_dentry_release,
400 };
401
402 /* For other dentries */
403 static const struct dentry_operations autofs4_dentry_operations = {
404 .d_revalidate = autofs4_revalidate,
405 .d_release = autofs4_dentry_release,
406 };
407
408 static struct dentry *autofs4_lookup_active(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
409 {
410 unsigned int len = name->len;
411 unsigned int hash = name->hash;
412 const unsigned char *str = name->name;
413 struct list_head *p, *head;
414
415 spin_lock(&dcache_lock);
416 spin_lock(&sbi->lookup_lock);
417 head = &sbi->active_list;
418 list_for_each(p, head) {
419 struct autofs_info *ino;
420 struct dentry *dentry;
421 struct qstr *qstr;
422
423 ino = list_entry(p, struct autofs_info, active);
424 dentry = ino->dentry;
425
426 spin_lock(&dentry->d_lock);
427
428 /* Already gone? */
429 if (atomic_read(&dentry->d_count) == 0)
430 goto next;
431
432 qstr = &dentry->d_name;
433
434 if (dentry->d_name.hash != hash)
435 goto next;
436 if (dentry->d_parent != parent)
437 goto next;
438
439 if (qstr->len != len)
440 goto next;
441 if (memcmp(qstr->name, str, len))
442 goto next;
443
444 if (d_unhashed(dentry)) {
445 dget(dentry);
446 spin_unlock(&dentry->d_lock);
447 spin_unlock(&sbi->lookup_lock);
448 spin_unlock(&dcache_lock);
449 return dentry;
450 }
451 next:
452 spin_unlock(&dentry->d_lock);
453 }
454 spin_unlock(&sbi->lookup_lock);
455 spin_unlock(&dcache_lock);
456
457 return NULL;
458 }
459
460 static struct dentry *autofs4_lookup_expiring(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
461 {
462 unsigned int len = name->len;
463 unsigned int hash = name->hash;
464 const unsigned char *str = name->name;
465 struct list_head *p, *head;
466
467 spin_lock(&dcache_lock);
468 spin_lock(&sbi->lookup_lock);
469 head = &sbi->expiring_list;
470 list_for_each(p, head) {
471 struct autofs_info *ino;
472 struct dentry *dentry;
473 struct qstr *qstr;
474
475 ino = list_entry(p, struct autofs_info, expiring);
476 dentry = ino->dentry;
477
478 spin_lock(&dentry->d_lock);
479
480 /* Bad luck, we've already been dentry_iput */
481 if (!dentry->d_inode)
482 goto next;
483
484 qstr = &dentry->d_name;
485
486 if (dentry->d_name.hash != hash)
487 goto next;
488 if (dentry->d_parent != parent)
489 goto next;
490
491 if (qstr->len != len)
492 goto next;
493 if (memcmp(qstr->name, str, len))
494 goto next;
495
496 if (d_unhashed(dentry)) {
497 dget(dentry);
498 spin_unlock(&dentry->d_lock);
499 spin_unlock(&sbi->lookup_lock);
500 spin_unlock(&dcache_lock);
501 return dentry;
502 }
503 next:
504 spin_unlock(&dentry->d_lock);
505 }
506 spin_unlock(&sbi->lookup_lock);
507 spin_unlock(&dcache_lock);
508
509 return NULL;
510 }
511
512 /* Lookups in the root directory */
513 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
514 {
515 struct autofs_sb_info *sbi;
516 struct autofs_info *ino;
517 struct dentry *expiring, *unhashed;
518 int oz_mode;
519
520 DPRINTK("name = %.*s",
521 dentry->d_name.len, dentry->d_name.name);
522
523 /* File name too long to exist */
524 if (dentry->d_name.len > NAME_MAX)
525 return ERR_PTR(-ENAMETOOLONG);
526
527 sbi = autofs4_sbi(dir->i_sb);
528 oz_mode = autofs4_oz_mode(sbi);
529
530 DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
531 current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
532
533 unhashed = autofs4_lookup_active(sbi, dentry->d_parent, &dentry->d_name);
534 if (unhashed) {
535 dentry = unhashed;
536 ino = autofs4_dentry_ino(dentry);
537 } else {
538 /*
539 * Mark the dentry incomplete but don't hash it. We do this
540 * to serialize our inode creation operations (symlink and
541 * mkdir) which prevents deadlock during the callback to
542 * the daemon. Subsequent user space lookups for the same
543 * dentry are placed on the wait queue while the daemon
544 * itself is allowed passage unresticted so the create
545 * operation itself can then hash the dentry. Finally,
546 * we check for the hashed dentry and return the newly
547 * hashed dentry.
548 */
549 dentry->d_op = &autofs4_root_dentry_operations;
550
551 /*
552 * And we need to ensure that the same dentry is used for
553 * all following lookup calls until it is hashed so that
554 * the dentry flags are persistent throughout the request.
555 */
556 ino = autofs4_init_ino(NULL, sbi, 0555);
557 if (!ino)
558 return ERR_PTR(-ENOMEM);
559
560 dentry->d_fsdata = ino;
561 ino->dentry = dentry;
562
563 autofs4_add_active(dentry);
564
565 d_instantiate(dentry, NULL);
566 }
567
568 if (!oz_mode) {
569 mutex_unlock(&dir->i_mutex);
570 expiring = autofs4_lookup_expiring(sbi,
571 dentry->d_parent,
572 &dentry->d_name);
573 if (expiring) {
574 /*
575 * If we are racing with expire the request might not
576 * be quite complete but the directory has been removed
577 * so it must have been successful, so just wait for it.
578 */
579 autofs4_expire_wait(expiring);
580 autofs4_del_expiring(expiring);
581 dput(expiring);
582 }
583
584 spin_lock(&sbi->fs_lock);
585 ino->flags |= AUTOFS_INF_PENDING;
586 spin_unlock(&sbi->fs_lock);
587 if (dentry->d_op && dentry->d_op->d_revalidate)
588 (dentry->d_op->d_revalidate)(dentry, nd);
589 mutex_lock(&dir->i_mutex);
590 }
591
592 /*
593 * If we are still pending, check if we had to handle
594 * a signal. If so we can force a restart..
595 */
596 if (ino->flags & AUTOFS_INF_PENDING) {
597 /* See if we were interrupted */
598 if (signal_pending(current)) {
599 sigset_t *sigset = &current->pending.signal;
600 if (sigismember (sigset, SIGKILL) ||
601 sigismember (sigset, SIGQUIT) ||
602 sigismember (sigset, SIGINT)) {
603 if (unhashed)
604 dput(unhashed);
605 return ERR_PTR(-ERESTARTNOINTR);
606 }
607 }
608 if (!oz_mode) {
609 spin_lock(&sbi->fs_lock);
610 ino->flags &= ~AUTOFS_INF_PENDING;
611 spin_unlock(&sbi->fs_lock);
612 }
613 }
614
615 /*
616 * If this dentry is unhashed, then we shouldn't honour this
617 * lookup. Returning ENOENT here doesn't do the right thing
618 * for all system calls, but it should be OK for the operations
619 * we permit from an autofs.
620 */
621 if (!oz_mode && d_unhashed(dentry)) {
622 /*
623 * A user space application can (and has done in the past)
624 * remove and re-create this directory during the callback.
625 * This can leave us with an unhashed dentry, but a
626 * successful mount! So we need to perform another
627 * cached lookup in case the dentry now exists.
628 */
629 struct dentry *parent = dentry->d_parent;
630 struct dentry *new = d_lookup(parent, &dentry->d_name);
631 if (new != NULL)
632 dentry = new;
633 else
634 dentry = ERR_PTR(-ENOENT);
635
636 if (unhashed)
637 dput(unhashed);
638
639 return dentry;
640 }
641
642 if (unhashed)
643 return unhashed;
644
645 return NULL;
646 }
647
648 static int autofs4_dir_symlink(struct inode *dir,
649 struct dentry *dentry,
650 const char *symname)
651 {
652 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
653 struct autofs_info *ino = autofs4_dentry_ino(dentry);
654 struct autofs_info *p_ino;
655 struct inode *inode;
656 char *cp;
657
658 DPRINTK("%s <- %.*s", symname,
659 dentry->d_name.len, dentry->d_name.name);
660
661 if (!autofs4_oz_mode(sbi))
662 return -EACCES;
663
664 ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
665 if (!ino)
666 return -ENOMEM;
667
668 autofs4_del_active(dentry);
669
670 ino->size = strlen(symname);
671 cp = kmalloc(ino->size + 1, GFP_KERNEL);
672 if (!cp) {
673 if (!dentry->d_fsdata)
674 kfree(ino);
675 return -ENOMEM;
676 }
677
678 strcpy(cp, symname);
679
680 inode = autofs4_get_inode(dir->i_sb, ino);
681 if (!inode) {
682 kfree(cp);
683 if (!dentry->d_fsdata)
684 kfree(ino);
685 return -ENOMEM;
686 }
687 d_add(dentry, inode);
688
689 if (dir == dir->i_sb->s_root->d_inode)
690 dentry->d_op = &autofs4_root_dentry_operations;
691 else
692 dentry->d_op = &autofs4_dentry_operations;
693
694 dentry->d_fsdata = ino;
695 ino->dentry = dget(dentry);
696 atomic_inc(&ino->count);
697 p_ino = autofs4_dentry_ino(dentry->d_parent);
698 if (p_ino && dentry->d_parent != dentry)
699 atomic_inc(&p_ino->count);
700 ino->inode = inode;
701
702 ino->u.symlink = cp;
703 dir->i_mtime = CURRENT_TIME;
704
705 return 0;
706 }
707
708 /*
709 * NOTE!
710 *
711 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
712 * that the file no longer exists. However, doing that means that the
713 * VFS layer can turn the dentry into a negative dentry. We don't want
714 * this, because the unlink is probably the result of an expire.
715 * We simply d_drop it and add it to a expiring list in the super block,
716 * which allows the dentry lookup to check for an incomplete expire.
717 *
718 * If a process is blocked on the dentry waiting for the expire to finish,
719 * it will invalidate the dentry and try to mount with a new one.
720 *
721 * Also see autofs4_dir_rmdir()..
722 */
723 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
724 {
725 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
726 struct autofs_info *ino = autofs4_dentry_ino(dentry);
727 struct autofs_info *p_ino;
728
729 /* This allows root to remove symlinks */
730 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
731 return -EACCES;
732
733 if (atomic_dec_and_test(&ino->count)) {
734 p_ino = autofs4_dentry_ino(dentry->d_parent);
735 if (p_ino && dentry->d_parent != dentry)
736 atomic_dec(&p_ino->count);
737 }
738 dput(ino->dentry);
739
740 dentry->d_inode->i_size = 0;
741 clear_nlink(dentry->d_inode);
742
743 dir->i_mtime = CURRENT_TIME;
744
745 spin_lock(&dcache_lock);
746 autofs4_add_expiring(dentry);
747 spin_lock(&dentry->d_lock);
748 __d_drop(dentry);
749 spin_unlock(&dentry->d_lock);
750 spin_unlock(&dcache_lock);
751
752 return 0;
753 }
754
755 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
756 {
757 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
758 struct autofs_info *ino = autofs4_dentry_ino(dentry);
759 struct autofs_info *p_ino;
760
761 DPRINTK("dentry %p, removing %.*s",
762 dentry, dentry->d_name.len, dentry->d_name.name);
763
764 if (!autofs4_oz_mode(sbi))
765 return -EACCES;
766
767 spin_lock(&dcache_lock);
768 if (!list_empty(&dentry->d_subdirs)) {
769 spin_unlock(&dcache_lock);
770 return -ENOTEMPTY;
771 }
772 autofs4_add_expiring(dentry);
773 spin_lock(&dentry->d_lock);
774 __d_drop(dentry);
775 spin_unlock(&dentry->d_lock);
776 spin_unlock(&dcache_lock);
777
778 if (atomic_dec_and_test(&ino->count)) {
779 p_ino = autofs4_dentry_ino(dentry->d_parent);
780 if (p_ino && dentry->d_parent != dentry)
781 atomic_dec(&p_ino->count);
782 }
783 dput(ino->dentry);
784 dentry->d_inode->i_size = 0;
785 clear_nlink(dentry->d_inode);
786
787 if (dir->i_nlink)
788 drop_nlink(dir);
789
790 return 0;
791 }
792
793 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
794 {
795 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
796 struct autofs_info *ino = autofs4_dentry_ino(dentry);
797 struct autofs_info *p_ino;
798 struct inode *inode;
799
800 if (!autofs4_oz_mode(sbi))
801 return -EACCES;
802
803 DPRINTK("dentry %p, creating %.*s",
804 dentry, dentry->d_name.len, dentry->d_name.name);
805
806 ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
807 if (!ino)
808 return -ENOMEM;
809
810 autofs4_del_active(dentry);
811
812 inode = autofs4_get_inode(dir->i_sb, ino);
813 if (!inode) {
814 if (!dentry->d_fsdata)
815 kfree(ino);
816 return -ENOMEM;
817 }
818 d_add(dentry, inode);
819
820 if (dir == dir->i_sb->s_root->d_inode)
821 dentry->d_op = &autofs4_root_dentry_operations;
822 else
823 dentry->d_op = &autofs4_dentry_operations;
824
825 dentry->d_fsdata = ino;
826 ino->dentry = dget(dentry);
827 atomic_inc(&ino->count);
828 p_ino = autofs4_dentry_ino(dentry->d_parent);
829 if (p_ino && dentry->d_parent != dentry)
830 atomic_inc(&p_ino->count);
831 ino->inode = inode;
832 inc_nlink(dir);
833 dir->i_mtime = CURRENT_TIME;
834
835 return 0;
836 }
837
838 /* Get/set timeout ioctl() operation */
839 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
840 unsigned long __user *p)
841 {
842 int rv;
843 unsigned long ntimeout;
844
845 if ((rv = get_user(ntimeout, p)) ||
846 (rv = put_user(sbi->exp_timeout/HZ, p)))
847 return rv;
848
849 if (ntimeout > ULONG_MAX/HZ)
850 sbi->exp_timeout = 0;
851 else
852 sbi->exp_timeout = ntimeout * HZ;
853
854 return 0;
855 }
856
857 /* Return protocol version */
858 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
859 {
860 return put_user(sbi->version, p);
861 }
862
863 /* Return protocol sub version */
864 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
865 {
866 return put_user(sbi->sub_version, p);
867 }
868
869 /*
870 * Tells the daemon whether it can umount the autofs mount.
871 */
872 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
873 {
874 int status = 0;
875
876 if (may_umount(mnt))
877 status = 1;
878
879 DPRINTK("returning %d", status);
880
881 status = put_user(status, p);
882
883 return status;
884 }
885
886 /* Identify autofs4_dentries - this is so we can tell if there's
887 an extra dentry refcount or not. We only hold a refcount on the
888 dentry if its non-negative (ie, d_inode != NULL)
889 */
890 int is_autofs4_dentry(struct dentry *dentry)
891 {
892 return dentry && dentry->d_inode &&
893 (dentry->d_op == &autofs4_root_dentry_operations ||
894 dentry->d_op == &autofs4_dentry_operations) &&
895 dentry->d_fsdata != NULL;
896 }
897
898 /*
899 * ioctl()'s on the root directory is the chief method for the daemon to
900 * generate kernel reactions
901 */
902 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
903 unsigned int cmd, unsigned long arg)
904 {
905 struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
906 void __user *p = (void __user *)arg;
907
908 DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
909 cmd,arg,sbi,task_pgrp_nr(current));
910
911 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
912 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
913 return -ENOTTY;
914
915 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
916 return -EPERM;
917
918 switch(cmd) {
919 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
920 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
921 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
922 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
923 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
924 autofs4_catatonic_mode(sbi);
925 return 0;
926 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
927 return autofs4_get_protover(sbi, p);
928 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
929 return autofs4_get_protosubver(sbi, p);
930 case AUTOFS_IOC_SETTIMEOUT:
931 return autofs4_get_set_timeout(sbi, p);
932
933 case AUTOFS_IOC_ASKUMOUNT:
934 return autofs4_ask_umount(filp->f_path.mnt, p);
935
936 /* return a single thing to expire */
937 case AUTOFS_IOC_EXPIRE:
938 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
939 /* same as above, but can send multiple expires through pipe */
940 case AUTOFS_IOC_EXPIRE_MULTI:
941 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
942
943 default:
944 return -ENOSYS;
945 }
946 }
Linux kernel - Deliverables
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