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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/slab.h>
19#include <linux/param.h>
20#include <linux/time.h>
21#include <linux/compat.h>
22#include <linux/mutex.h>
23
24#include "autofs_i.h"
25
26static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
27static int autofs4_dir_unlink(struct inode *,struct dentry *);
28static int autofs4_dir_rmdir(struct inode *,struct dentry *);
29static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
30static long autofs4_root_ioctl(struct file *,unsigned int,unsigned long);
31#ifdef CONFIG_COMPAT
32static long autofs4_root_compat_ioctl(struct file *,unsigned int,unsigned long);
33#endif
34static int autofs4_dir_open(struct inode *inode, struct file *file);
35static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
36static struct vfsmount *autofs4_d_automount(struct path *);
37static int autofs4_d_manage(struct dentry *, bool);
38static void autofs4_dentry_release(struct dentry *);
39
40const struct file_operations autofs4_root_operations = {
41 .open = dcache_dir_open,
42 .release = dcache_dir_close,
43 .read = generic_read_dir,
44 .readdir = dcache_readdir,
45 .llseek = dcache_dir_lseek,
46 .unlocked_ioctl = autofs4_root_ioctl,
47#ifdef CONFIG_COMPAT
48 .compat_ioctl = autofs4_root_compat_ioctl,
49#endif
50};
51
52const struct file_operations autofs4_dir_operations = {
53 .open = autofs4_dir_open,
54 .release = dcache_dir_close,
55 .read = generic_read_dir,
56 .readdir = dcache_readdir,
57 .llseek = dcache_dir_lseek,
58};
59
60const struct inode_operations autofs4_dir_inode_operations = {
61 .lookup = autofs4_lookup,
62 .unlink = autofs4_dir_unlink,
63 .symlink = autofs4_dir_symlink,
64 .mkdir = autofs4_dir_mkdir,
65 .rmdir = autofs4_dir_rmdir,
66};
67
68const struct dentry_operations autofs4_dentry_operations = {
69 .d_automount = autofs4_d_automount,
70 .d_manage = autofs4_d_manage,
71 .d_release = autofs4_dentry_release,
72};
73
74static void autofs4_add_active(struct dentry *dentry)
75{
76 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
77 struct autofs_info *ino = autofs4_dentry_ino(dentry);
78 if (ino) {
79 spin_lock(&sbi->lookup_lock);
80 if (!ino->active_count) {
81 if (list_empty(&ino->active))
82 list_add(&ino->active, &sbi->active_list);
83 }
84 ino->active_count++;
85 spin_unlock(&sbi->lookup_lock);
86 }
87 return;
88}
89
90static void autofs4_del_active(struct dentry *dentry)
91{
92 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
93 struct autofs_info *ino = autofs4_dentry_ino(dentry);
94 if (ino) {
95 spin_lock(&sbi->lookup_lock);
96 ino->active_count--;
97 if (!ino->active_count) {
98 if (!list_empty(&ino->active))
99 list_del_init(&ino->active);
100 }
101 spin_unlock(&sbi->lookup_lock);
102 }
103 return;
104}
105
106static int autofs4_dir_open(struct inode *inode, struct file *file)
107{
108 struct dentry *dentry = file->f_path.dentry;
109 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
110
111 DPRINTK("file=%p dentry=%p %.*s",
112 file, dentry, dentry->d_name.len, dentry->d_name.name);
113
114 if (autofs4_oz_mode(sbi))
115 goto out;
116
117 /*
118 * An empty directory in an autofs file system is always a
119 * mount point. The daemon must have failed to mount this
120 * during lookup so it doesn't exist. This can happen, for
121 * example, if user space returns an incorrect status for a
122 * mount request. Otherwise we're doing a readdir on the
123 * autofs file system so just let the libfs routines handle
124 * it.
125 */
126 spin_lock(&sbi->lookup_lock);
127 spin_lock(&dentry->d_lock);
128 if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
129 spin_unlock(&dentry->d_lock);
130 spin_unlock(&sbi->lookup_lock);
131 return -ENOENT;
132 }
133 spin_unlock(&dentry->d_lock);
134 spin_unlock(&sbi->lookup_lock);
135
136out:
137 return dcache_dir_open(inode, file);
138}
139
140static void autofs4_dentry_release(struct dentry *de)
141{
142 struct autofs_info *ino = autofs4_dentry_ino(de);
143 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
144
145 DPRINTK("releasing %p", de);
146
147 if (!ino)
148 return;
149
150 if (sbi) {
151 spin_lock(&sbi->lookup_lock);
152 if (!list_empty(&ino->active))
153 list_del(&ino->active);
154 if (!list_empty(&ino->expiring))
155 list_del(&ino->expiring);
156 spin_unlock(&sbi->lookup_lock);
157 }
158
159 autofs4_free_ino(ino);
160}
161
162static struct dentry *autofs4_lookup_active(struct dentry *dentry)
163{
164 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
165 struct dentry *parent = dentry->d_parent;
166 struct qstr *name = &dentry->d_name;
167 unsigned int len = name->len;
168 unsigned int hash = name->hash;
169 const unsigned char *str = name->name;
170 struct list_head *p, *head;
171
172 spin_lock(&sbi->lookup_lock);
173 head = &sbi->active_list;
174 list_for_each(p, head) {
175 struct autofs_info *ino;
176 struct dentry *active;
177 struct qstr *qstr;
178
179 ino = list_entry(p, struct autofs_info, active);
180 active = ino->dentry;
181
182 spin_lock(&active->d_lock);
183
184 /* Already gone? */
185 if (active->d_count == 0)
186 goto next;
187
188 qstr = &active->d_name;
189
190 if (active->d_name.hash != hash)
191 goto next;
192 if (active->d_parent != parent)
193 goto next;
194
195 if (qstr->len != len)
196 goto next;
197 if (memcmp(qstr->name, str, len))
198 goto next;
199
200 if (d_unhashed(active)) {
201 dget_dlock(active);
202 spin_unlock(&active->d_lock);
203 spin_unlock(&sbi->lookup_lock);
204 return active;
205 }
206next:
207 spin_unlock(&active->d_lock);
208 }
209 spin_unlock(&sbi->lookup_lock);
210
211 return NULL;
212}
213
214static struct dentry *autofs4_lookup_expiring(struct dentry *dentry)
215{
216 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
217 struct dentry *parent = dentry->d_parent;
218 struct qstr *name = &dentry->d_name;
219 unsigned int len = name->len;
220 unsigned int hash = name->hash;
221 const unsigned char *str = name->name;
222 struct list_head *p, *head;
223
224 spin_lock(&sbi->lookup_lock);
225 head = &sbi->expiring_list;
226 list_for_each(p, head) {
227 struct autofs_info *ino;
228 struct dentry *expiring;
229 struct qstr *qstr;
230
231 ino = list_entry(p, struct autofs_info, expiring);
232 expiring = ino->dentry;
233
234 spin_lock(&expiring->d_lock);
235
236 /* Bad luck, we've already been dentry_iput */
237 if (!expiring->d_inode)
238 goto next;
239
240 qstr = &expiring->d_name;
241
242 if (expiring->d_name.hash != hash)
243 goto next;
244 if (expiring->d_parent != parent)
245 goto next;
246
247 if (qstr->len != len)
248 goto next;
249 if (memcmp(qstr->name, str, len))
250 goto next;
251
252 if (d_unhashed(expiring)) {
253 dget_dlock(expiring);
254 spin_unlock(&expiring->d_lock);
255 spin_unlock(&sbi->lookup_lock);
256 return expiring;
257 }
258next:
259 spin_unlock(&expiring->d_lock);
260 }
261 spin_unlock(&sbi->lookup_lock);
262
263 return NULL;
264}
265
266static int autofs4_mount_wait(struct dentry *dentry)
267{
268 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
269 struct autofs_info *ino = autofs4_dentry_ino(dentry);
270 int status = 0;
271
272 if (ino->flags & AUTOFS_INF_PENDING) {
273 DPRINTK("waiting for mount name=%.*s",
274 dentry->d_name.len, dentry->d_name.name);
275 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
276 DPRINTK("mount wait done status=%d", status);
277 }
278 ino->last_used = jiffies;
279 return status;
280}
281
282static int do_expire_wait(struct dentry *dentry)
283{
284 struct dentry *expiring;
285
286 expiring = autofs4_lookup_expiring(dentry);
287 if (!expiring)
288 return autofs4_expire_wait(dentry);
289 else {
290 /*
291 * If we are racing with expire the request might not
292 * be quite complete, but the directory has been removed
293 * so it must have been successful, just wait for it.
294 */
295 autofs4_expire_wait(expiring);
296 autofs4_del_expiring(expiring);
297 dput(expiring);
298 }
299 return 0;
300}
301
302static struct dentry *autofs4_mountpoint_changed(struct path *path)
303{
304 struct dentry *dentry = path->dentry;
305 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
306
307 /*
308 * If this is an indirect mount the dentry could have gone away
309 * as a result of an expire and a new one created.
310 */
311 if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
312 struct dentry *parent = dentry->d_parent;
313 struct autofs_info *ino;
314 struct dentry *new = d_lookup(parent, &dentry->d_name);
315 if (!new)
316 return NULL;
317 ino = autofs4_dentry_ino(new);
318 ino->last_used = jiffies;
319 dput(path->dentry);
320 path->dentry = new;
321 }
322 return path->dentry;
323}
324
325static struct vfsmount *autofs4_d_automount(struct path *path)
326{
327 struct dentry *dentry = path->dentry;
328 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
329 struct autofs_info *ino = autofs4_dentry_ino(dentry);
330 int status;
331
332 DPRINTK("dentry=%p %.*s",
333 dentry, dentry->d_name.len, dentry->d_name.name);
334
335 /* The daemon never triggers a mount. */
336 if (autofs4_oz_mode(sbi))
337 return NULL;
338
339 /*
340 * If an expire request is pending everyone must wait.
341 * If the expire fails we're still mounted so continue
342 * the follow and return. A return of -EAGAIN (which only
343 * happens with indirect mounts) means the expire completed
344 * and the directory was removed, so just go ahead and try
345 * the mount.
346 */
347 status = do_expire_wait(dentry);
348 if (status && status != -EAGAIN)
349 return NULL;
350
351 /* Callback to the daemon to perform the mount or wait */
352 spin_lock(&sbi->fs_lock);
353 if (ino->flags & AUTOFS_INF_PENDING) {
354 spin_unlock(&sbi->fs_lock);
355 status = autofs4_mount_wait(dentry);
356 if (status)
357 return ERR_PTR(status);
358 spin_lock(&sbi->fs_lock);
359 goto done;
360 }
361
362 /*
363 * If the dentry is a symlink it's equivalent to a directory
364 * having d_mountpoint() true, so there's no need to call back
365 * to the daemon.
366 */
367 if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode))
368 goto done;
369 if (!d_mountpoint(dentry)) {
370 /*
371 * It's possible that user space hasn't removed directories
372 * after umounting a rootless multi-mount, although it
373 * should. For v5 have_submounts() is sufficient to handle
374 * this because the leaves of the directory tree under the
375 * mount never trigger mounts themselves (they have an autofs
376 * trigger mount mounted on them). But v4 pseudo direct mounts
377 * do need the leaves to to trigger mounts. In this case we
378 * have no choice but to use the list_empty() check and
379 * require user space behave.
380 */
381 if (sbi->version > 4) {
382 if (have_submounts(dentry))
383 goto done;
384 } else {
385 spin_lock(&dentry->d_lock);
386 if (!list_empty(&dentry->d_subdirs)) {
387 spin_unlock(&dentry->d_lock);
388 goto done;
389 }
390 spin_unlock(&dentry->d_lock);
391 }
392 ino->flags |= AUTOFS_INF_PENDING;
393 spin_unlock(&sbi->fs_lock);
394 status = autofs4_mount_wait(dentry);
395 if (status)
396 return ERR_PTR(status);
397 spin_lock(&sbi->fs_lock);
398 ino->flags &= ~AUTOFS_INF_PENDING;
399 }
400done:
401 if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
402 /*
403 * Any needed mounting has been completed and the path
404 * updated so clear DCACHE_NEED_AUTOMOUNT so we don't
405 * call ->d_automount() on rootless multi-mounts since
406 * it can lead to an incorrect ELOOP error return.
407 *
408 * Only clear DMANAGED_AUTOMOUNT for rootless multi-mounts and
409 * symlinks as in all other cases the dentry will be covered by
410 * an actual mount so ->d_automount() won't be called during
411 * the follow.
412 */
413 spin_lock(&dentry->d_lock);
414 if ((!d_mountpoint(dentry) &&
415 !list_empty(&dentry->d_subdirs)) ||
416 (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)))
417 __managed_dentry_clear_automount(dentry);
418 spin_unlock(&dentry->d_lock);
419 }
420 spin_unlock(&sbi->fs_lock);
421
422 /* Mount succeeded, check if we ended up with a new dentry */
423 dentry = autofs4_mountpoint_changed(path);
424 if (!dentry)
425 return ERR_PTR(-ENOENT);
426
427 return NULL;
428}
429
430int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
431{
432 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
433
434 DPRINTK("dentry=%p %.*s",
435 dentry, dentry->d_name.len, dentry->d_name.name);
436
437 /* The daemon never waits. */
438 if (autofs4_oz_mode(sbi)) {
439 if (rcu_walk)
440 return 0;
441 if (!d_mountpoint(dentry))
442 return -EISDIR;
443 return 0;
444 }
445
446 /* We need to sleep, so we need pathwalk to be in ref-mode */
447 if (rcu_walk)
448 return -ECHILD;
449
450 /* Wait for pending expires */
451 do_expire_wait(dentry);
452
453 /*
454 * This dentry may be under construction so wait on mount
455 * completion.
456 */
457 return autofs4_mount_wait(dentry);
458}
459
460/* Lookups in the root directory */
461static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
462{
463 struct autofs_sb_info *sbi;
464 struct autofs_info *ino;
465 struct dentry *active;
466
467 DPRINTK("name = %.*s", dentry->d_name.len, dentry->d_name.name);
468
469 /* File name too long to exist */
470 if (dentry->d_name.len > NAME_MAX)
471 return ERR_PTR(-ENAMETOOLONG);
472
473 sbi = autofs4_sbi(dir->i_sb);
474
475 DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
476 current->pid, task_pgrp_nr(current), sbi->catatonic,
477 autofs4_oz_mode(sbi));
478
479 active = autofs4_lookup_active(dentry);
480 if (active) {
481 return active;
482 } else {
483 /*
484 * A dentry that is not within the root can never trigger a
485 * mount operation, unless the directory already exists, so we
486 * can return fail immediately. The daemon however does need
487 * to create directories within the file system.
488 */
489 if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
490 return ERR_PTR(-ENOENT);
491
492 /* Mark entries in the root as mount triggers */
493 if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent))
494 __managed_dentry_set_managed(dentry);
495
496 ino = autofs4_new_ino(sbi);
497 if (!ino)
498 return ERR_PTR(-ENOMEM);
499
500 dentry->d_fsdata = ino;
501 ino->dentry = dentry;
502
503 autofs4_add_active(dentry);
504
505 d_instantiate(dentry, NULL);
506 }
507 return NULL;
508}
509
510static int autofs4_dir_symlink(struct inode *dir,
511 struct dentry *dentry,
512 const char *symname)
513{
514 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
515 struct autofs_info *ino = autofs4_dentry_ino(dentry);
516 struct autofs_info *p_ino;
517 struct inode *inode;
518 size_t size = strlen(symname);
519 char *cp;
520
521 DPRINTK("%s <- %.*s", symname,
522 dentry->d_name.len, dentry->d_name.name);
523
524 if (!autofs4_oz_mode(sbi))
525 return -EACCES;
526
527 BUG_ON(!ino);
528
529 autofs4_clean_ino(ino);
530
531 autofs4_del_active(dentry);
532
533 cp = kmalloc(size + 1, GFP_KERNEL);
534 if (!cp)
535 return -ENOMEM;
536
537 strcpy(cp, symname);
538
539 inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555);
540 if (!inode) {
541 kfree(cp);
542 if (!dentry->d_fsdata)
543 kfree(ino);
544 return -ENOMEM;
545 }
546 inode->i_private = cp;
547 inode->i_size = size;
548 d_add(dentry, inode);
549
550 dget(dentry);
551 atomic_inc(&ino->count);
552 p_ino = autofs4_dentry_ino(dentry->d_parent);
553 if (p_ino && dentry->d_parent != dentry)
554 atomic_inc(&p_ino->count);
555
556 dir->i_mtime = CURRENT_TIME;
557
558 return 0;
559}
560
561/*
562 * NOTE!
563 *
564 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
565 * that the file no longer exists. However, doing that means that the
566 * VFS layer can turn the dentry into a negative dentry. We don't want
567 * this, because the unlink is probably the result of an expire.
568 * We simply d_drop it and add it to a expiring list in the super block,
569 * which allows the dentry lookup to check for an incomplete expire.
570 *
571 * If a process is blocked on the dentry waiting for the expire to finish,
572 * it will invalidate the dentry and try to mount with a new one.
573 *
574 * Also see autofs4_dir_rmdir()..
575 */
576static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
577{
578 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
579 struct autofs_info *ino = autofs4_dentry_ino(dentry);
580 struct autofs_info *p_ino;
581
582 /* This allows root to remove symlinks */
583 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
584 return -EACCES;
585
586 if (atomic_dec_and_test(&ino->count)) {
587 p_ino = autofs4_dentry_ino(dentry->d_parent);
588 if (p_ino && dentry->d_parent != dentry)
589 atomic_dec(&p_ino->count);
590 }
591 dput(ino->dentry);
592
593 dentry->d_inode->i_size = 0;
594 clear_nlink(dentry->d_inode);
595
596 dir->i_mtime = CURRENT_TIME;
597
598 spin_lock(&sbi->lookup_lock);
599 __autofs4_add_expiring(dentry);
600 spin_lock(&dentry->d_lock);
601 __d_drop(dentry);
602 spin_unlock(&dentry->d_lock);
603 spin_unlock(&sbi->lookup_lock);
604
605 return 0;
606}
607
608/*
609 * Version 4 of autofs provides a pseudo direct mount implementation
610 * that relies on directories at the leaves of a directory tree under
611 * an indirect mount to trigger mounts. To allow for this we need to
612 * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
613 * of the directory tree. There is no need to clear the automount flag
614 * following a mount or restore it after an expire because these mounts
615 * are always covered. However, it is necessary to ensure that these
616 * flags are clear on non-empty directories to avoid unnecessary calls
617 * during path walks.
618 */
619static void autofs_set_leaf_automount_flags(struct dentry *dentry)
620{
621 struct dentry *parent;
622
623 /* root and dentrys in the root are already handled */
624 if (IS_ROOT(dentry->d_parent))
625 return;
626
627 managed_dentry_set_managed(dentry);
628
629 parent = dentry->d_parent;
630 /* only consider parents below dentrys in the root */
631 if (IS_ROOT(parent->d_parent))
632 return;
633 managed_dentry_clear_managed(parent);
634 return;
635}
636
637static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
638{
639 struct list_head *d_child;
640 struct dentry *parent;
641
642 /* flags for dentrys in the root are handled elsewhere */
643 if (IS_ROOT(dentry->d_parent))
644 return;
645
646 managed_dentry_clear_managed(dentry);
647
648 parent = dentry->d_parent;
649 /* only consider parents below dentrys in the root */
650 if (IS_ROOT(parent->d_parent))
651 return;
652 d_child = &dentry->d_u.d_child;
653 /* Set parent managed if it's becoming empty */
654 if (d_child->next == &parent->d_subdirs &&
655 d_child->prev == &parent->d_subdirs)
656 managed_dentry_set_managed(parent);
657 return;
658}
659
660static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
661{
662 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
663 struct autofs_info *ino = autofs4_dentry_ino(dentry);
664 struct autofs_info *p_ino;
665
666 DPRINTK("dentry %p, removing %.*s",
667 dentry, dentry->d_name.len, dentry->d_name.name);
668
669 if (!autofs4_oz_mode(sbi))
670 return -EACCES;
671
672 spin_lock(&sbi->lookup_lock);
673 spin_lock(&dentry->d_lock);
674 if (!list_empty(&dentry->d_subdirs)) {
675 spin_unlock(&dentry->d_lock);
676 spin_unlock(&sbi->lookup_lock);
677 return -ENOTEMPTY;
678 }
679 __autofs4_add_expiring(dentry);
680 __d_drop(dentry);
681 spin_unlock(&dentry->d_lock);
682 spin_unlock(&sbi->lookup_lock);
683
684 if (sbi->version < 5)
685 autofs_clear_leaf_automount_flags(dentry);
686
687 if (atomic_dec_and_test(&ino->count)) {
688 p_ino = autofs4_dentry_ino(dentry->d_parent);
689 if (p_ino && dentry->d_parent != dentry)
690 atomic_dec(&p_ino->count);
691 }
692 dput(ino->dentry);
693 dentry->d_inode->i_size = 0;
694 clear_nlink(dentry->d_inode);
695
696 if (dir->i_nlink)
697 drop_nlink(dir);
698
699 return 0;
700}
701
702static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
703{
704 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
705 struct autofs_info *ino = autofs4_dentry_ino(dentry);
706 struct autofs_info *p_ino;
707 struct inode *inode;
708
709 if (!autofs4_oz_mode(sbi))
710 return -EACCES;
711
712 DPRINTK("dentry %p, creating %.*s",
713 dentry, dentry->d_name.len, dentry->d_name.name);
714
715 BUG_ON(!ino);
716
717 autofs4_clean_ino(ino);
718
719 autofs4_del_active(dentry);
720
721 inode = autofs4_get_inode(dir->i_sb, S_IFDIR | 0555);
722 if (!inode)
723 return -ENOMEM;
724 d_add(dentry, inode);
725
726 if (sbi->version < 5)
727 autofs_set_leaf_automount_flags(dentry);
728
729 dget(dentry);
730 atomic_inc(&ino->count);
731 p_ino = autofs4_dentry_ino(dentry->d_parent);
732 if (p_ino && dentry->d_parent != dentry)
733 atomic_inc(&p_ino->count);
734 inc_nlink(dir);
735 dir->i_mtime = CURRENT_TIME;
736
737 return 0;
738}
739
740/* Get/set timeout ioctl() operation */
741#ifdef CONFIG_COMPAT
742static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi,
743 compat_ulong_t __user *p)
744{
745 int rv;
746 unsigned long ntimeout;
747
748 if ((rv = get_user(ntimeout, p)) ||
749 (rv = put_user(sbi->exp_timeout/HZ, p)))
750 return rv;
751
752 if (ntimeout > UINT_MAX/HZ)
753 sbi->exp_timeout = 0;
754 else
755 sbi->exp_timeout = ntimeout * HZ;
756
757 return 0;
758}
759#endif
760
761static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
762 unsigned long __user *p)
763{
764 int rv;
765 unsigned long ntimeout;
766
767 if ((rv = get_user(ntimeout, p)) ||
768 (rv = put_user(sbi->exp_timeout/HZ, p)))
769 return rv;
770
771 if (ntimeout > ULONG_MAX/HZ)
772 sbi->exp_timeout = 0;
773 else
774 sbi->exp_timeout = ntimeout * HZ;
775
776 return 0;
777}
778
779/* Return protocol version */
780static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
781{
782 return put_user(sbi->version, p);
783}
784
785/* Return protocol sub version */
786static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
787{
788 return put_user(sbi->sub_version, p);
789}
790
791/*
792* Tells the daemon whether it can umount the autofs mount.
793*/
794static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
795{
796 int status = 0;
797
798 if (may_umount(mnt))
799 status = 1;
800
801 DPRINTK("returning %d", status);
802
803 status = put_user(status, p);
804
805 return status;
806}
807
808/* Identify autofs4_dentries - this is so we can tell if there's
809 an extra dentry refcount or not. We only hold a refcount on the
810 dentry if its non-negative (ie, d_inode != NULL)
811*/
812int is_autofs4_dentry(struct dentry *dentry)
813{
814 return dentry && dentry->d_inode &&
815 dentry->d_op == &autofs4_dentry_operations &&
816 dentry->d_fsdata != NULL;
817}
818
819/*
820 * ioctl()'s on the root directory is the chief method for the daemon to
821 * generate kernel reactions
822 */
823static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
824 unsigned int cmd, unsigned long arg)
825{
826 struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
827 void __user *p = (void __user *)arg;
828
829 DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
830 cmd,arg,sbi,task_pgrp_nr(current));
831
832 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
833 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
834 return -ENOTTY;
835
836 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
837 return -EPERM;
838
839 switch(cmd) {
840 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
841 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
842 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
843 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
844 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
845 autofs4_catatonic_mode(sbi);
846 return 0;
847 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
848 return autofs4_get_protover(sbi, p);
849 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
850 return autofs4_get_protosubver(sbi, p);
851 case AUTOFS_IOC_SETTIMEOUT:
852 return autofs4_get_set_timeout(sbi, p);
853#ifdef CONFIG_COMPAT
854 case AUTOFS_IOC_SETTIMEOUT32:
855 return autofs4_compat_get_set_timeout(sbi, p);
856#endif
857
858 case AUTOFS_IOC_ASKUMOUNT:
859 return autofs4_ask_umount(filp->f_path.mnt, p);
860
861 /* return a single thing to expire */
862 case AUTOFS_IOC_EXPIRE:
863 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
864 /* same as above, but can send multiple expires through pipe */
865 case AUTOFS_IOC_EXPIRE_MULTI:
866 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
867
868 default:
869 return -ENOSYS;
870 }
871}
872
873static long autofs4_root_ioctl(struct file *filp,
874 unsigned int cmd, unsigned long arg)
875{
876 struct inode *inode = filp->f_dentry->d_inode;
877 return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
878}
879
880#ifdef CONFIG_COMPAT
881static long autofs4_root_compat_ioctl(struct file *filp,
882 unsigned int cmd, unsigned long arg)
883{
884 struct inode *inode = filp->f_path.dentry->d_inode;
885 int ret;
886
887 if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
888 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
889 else
890 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd,
891 (unsigned long)compat_ptr(arg));
892
893 return ret;
894}
895#endif
1/*
2 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
3 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
4 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
5 *
6 * This file is part of the Linux kernel and is made available under
7 * the terms of the GNU General Public License, version 2, or at your
8 * option, any later version, incorporated herein by reference.
9 */
10
11#include <linux/capability.h>
12#include <linux/errno.h>
13#include <linux/stat.h>
14#include <linux/slab.h>
15#include <linux/param.h>
16#include <linux/time.h>
17#include <linux/compat.h>
18#include <linux/mutex.h>
19
20#include "autofs_i.h"
21
22static int autofs4_dir_symlink(struct inode *, struct dentry *, const char *);
23static int autofs4_dir_unlink(struct inode *, struct dentry *);
24static int autofs4_dir_rmdir(struct inode *, struct dentry *);
25static int autofs4_dir_mkdir(struct inode *, struct dentry *, umode_t);
26static long autofs4_root_ioctl(struct file *, unsigned int, unsigned long);
27#ifdef CONFIG_COMPAT
28static long autofs4_root_compat_ioctl(struct file *,
29 unsigned int, unsigned long);
30#endif
31static int autofs4_dir_open(struct inode *inode, struct file *file);
32static struct dentry *autofs4_lookup(struct inode *,
33 struct dentry *, unsigned int);
34static struct vfsmount *autofs4_d_automount(struct path *);
35static int autofs4_d_manage(struct dentry *, bool);
36static void autofs4_dentry_release(struct dentry *);
37
38const struct file_operations autofs4_root_operations = {
39 .open = dcache_dir_open,
40 .release = dcache_dir_close,
41 .read = generic_read_dir,
42 .iterate = dcache_readdir,
43 .llseek = dcache_dir_lseek,
44 .unlocked_ioctl = autofs4_root_ioctl,
45#ifdef CONFIG_COMPAT
46 .compat_ioctl = autofs4_root_compat_ioctl,
47#endif
48};
49
50const struct file_operations autofs4_dir_operations = {
51 .open = autofs4_dir_open,
52 .release = dcache_dir_close,
53 .read = generic_read_dir,
54 .iterate = dcache_readdir,
55 .llseek = dcache_dir_lseek,
56};
57
58const struct inode_operations autofs4_dir_inode_operations = {
59 .lookup = autofs4_lookup,
60 .unlink = autofs4_dir_unlink,
61 .symlink = autofs4_dir_symlink,
62 .mkdir = autofs4_dir_mkdir,
63 .rmdir = autofs4_dir_rmdir,
64};
65
66const struct dentry_operations autofs4_dentry_operations = {
67 .d_automount = autofs4_d_automount,
68 .d_manage = autofs4_d_manage,
69 .d_release = autofs4_dentry_release,
70};
71
72static void autofs4_add_active(struct dentry *dentry)
73{
74 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
75 struct autofs_info *ino;
76
77 ino = autofs4_dentry_ino(dentry);
78 if (ino) {
79 spin_lock(&sbi->lookup_lock);
80 if (!ino->active_count) {
81 if (list_empty(&ino->active))
82 list_add(&ino->active, &sbi->active_list);
83 }
84 ino->active_count++;
85 spin_unlock(&sbi->lookup_lock);
86 }
87}
88
89static void autofs4_del_active(struct dentry *dentry)
90{
91 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
92 struct autofs_info *ino;
93
94 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}
105
106static int autofs4_dir_open(struct inode *inode, struct file *file)
107{
108 struct dentry *dentry = file->f_path.dentry;
109 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
110
111 pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
112
113 if (autofs4_oz_mode(sbi))
114 goto out;
115
116 /*
117 * An empty directory in an autofs file system is always a
118 * mount point. The daemon must have failed to mount this
119 * during lookup so it doesn't exist. This can happen, for
120 * example, if user space returns an incorrect status for a
121 * mount request. Otherwise we're doing a readdir on the
122 * autofs file system so just let the libfs routines handle
123 * it.
124 */
125 spin_lock(&sbi->lookup_lock);
126 if (!d_mountpoint(dentry) && simple_empty(dentry)) {
127 spin_unlock(&sbi->lookup_lock);
128 return -ENOENT;
129 }
130 spin_unlock(&sbi->lookup_lock);
131
132out:
133 return dcache_dir_open(inode, file);
134}
135
136static void autofs4_dentry_release(struct dentry *de)
137{
138 struct autofs_info *ino = autofs4_dentry_ino(de);
139 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
140
141 pr_debug("releasing %p\n", de);
142
143 if (!ino)
144 return;
145
146 if (sbi) {
147 spin_lock(&sbi->lookup_lock);
148 if (!list_empty(&ino->active))
149 list_del(&ino->active);
150 if (!list_empty(&ino->expiring))
151 list_del(&ino->expiring);
152 spin_unlock(&sbi->lookup_lock);
153 }
154
155 autofs4_free_ino(ino);
156}
157
158static struct dentry *autofs4_lookup_active(struct dentry *dentry)
159{
160 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
161 struct dentry *parent = dentry->d_parent;
162 struct qstr *name = &dentry->d_name;
163 unsigned int len = name->len;
164 unsigned int hash = name->hash;
165 const unsigned char *str = name->name;
166 struct list_head *p, *head;
167
168 head = &sbi->active_list;
169 if (list_empty(head))
170 return NULL;
171 spin_lock(&sbi->lookup_lock);
172 list_for_each(p, head) {
173 struct autofs_info *ino;
174 struct dentry *active;
175 struct qstr *qstr;
176
177 ino = list_entry(p, struct autofs_info, active);
178 active = ino->dentry;
179
180 spin_lock(&active->d_lock);
181
182 /* Already gone? */
183 if ((int) d_count(active) <= 0)
184 goto next;
185
186 qstr = &active->d_name;
187
188 if (active->d_name.hash != hash)
189 goto next;
190 if (active->d_parent != parent)
191 goto next;
192
193 if (qstr->len != len)
194 goto next;
195 if (memcmp(qstr->name, str, len))
196 goto next;
197
198 if (d_unhashed(active)) {
199 dget_dlock(active);
200 spin_unlock(&active->d_lock);
201 spin_unlock(&sbi->lookup_lock);
202 return active;
203 }
204next:
205 spin_unlock(&active->d_lock);
206 }
207 spin_unlock(&sbi->lookup_lock);
208
209 return NULL;
210}
211
212static struct dentry *autofs4_lookup_expiring(struct dentry *dentry,
213 bool rcu_walk)
214{
215 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
216 struct dentry *parent = dentry->d_parent;
217 struct qstr *name = &dentry->d_name;
218 unsigned int len = name->len;
219 unsigned int hash = name->hash;
220 const unsigned char *str = name->name;
221 struct list_head *p, *head;
222
223 head = &sbi->expiring_list;
224 if (list_empty(head))
225 return NULL;
226 spin_lock(&sbi->lookup_lock);
227 list_for_each(p, head) {
228 struct autofs_info *ino;
229 struct dentry *expiring;
230 struct qstr *qstr;
231
232 if (rcu_walk) {
233 spin_unlock(&sbi->lookup_lock);
234 return ERR_PTR(-ECHILD);
235 }
236
237 ino = list_entry(p, struct autofs_info, expiring);
238 expiring = ino->dentry;
239
240 spin_lock(&expiring->d_lock);
241
242 /* We've already been dentry_iput or unlinked */
243 if (d_really_is_negative(expiring))
244 goto next;
245
246 qstr = &expiring->d_name;
247
248 if (expiring->d_name.hash != hash)
249 goto next;
250 if (expiring->d_parent != parent)
251 goto next;
252
253 if (qstr->len != len)
254 goto next;
255 if (memcmp(qstr->name, str, len))
256 goto next;
257
258 if (d_unhashed(expiring)) {
259 dget_dlock(expiring);
260 spin_unlock(&expiring->d_lock);
261 spin_unlock(&sbi->lookup_lock);
262 return expiring;
263 }
264next:
265 spin_unlock(&expiring->d_lock);
266 }
267 spin_unlock(&sbi->lookup_lock);
268
269 return NULL;
270}
271
272static int autofs4_mount_wait(struct dentry *dentry, bool rcu_walk)
273{
274 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
275 struct autofs_info *ino = autofs4_dentry_ino(dentry);
276 int status = 0;
277
278 if (ino->flags & AUTOFS_INF_PENDING) {
279 if (rcu_walk)
280 return -ECHILD;
281 pr_debug("waiting for mount name=%pd\n", dentry);
282 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
283 pr_debug("mount wait done status=%d\n", status);
284 }
285 ino->last_used = jiffies;
286 return status;
287}
288
289static int do_expire_wait(struct dentry *dentry, bool rcu_walk)
290{
291 struct dentry *expiring;
292
293 expiring = autofs4_lookup_expiring(dentry, rcu_walk);
294 if (IS_ERR(expiring))
295 return PTR_ERR(expiring);
296 if (!expiring)
297 return autofs4_expire_wait(dentry, rcu_walk);
298 else {
299 /*
300 * If we are racing with expire the request might not
301 * be quite complete, but the directory has been removed
302 * so it must have been successful, just wait for it.
303 */
304 autofs4_expire_wait(expiring, 0);
305 autofs4_del_expiring(expiring);
306 dput(expiring);
307 }
308 return 0;
309}
310
311static struct dentry *autofs4_mountpoint_changed(struct path *path)
312{
313 struct dentry *dentry = path->dentry;
314 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
315
316 /*
317 * If this is an indirect mount the dentry could have gone away
318 * as a result of an expire and a new one created.
319 */
320 if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
321 struct dentry *parent = dentry->d_parent;
322 struct autofs_info *ino;
323 struct dentry *new;
324
325 new = d_lookup(parent, &dentry->d_name);
326 if (!new)
327 return NULL;
328 ino = autofs4_dentry_ino(new);
329 ino->last_used = jiffies;
330 dput(path->dentry);
331 path->dentry = new;
332 }
333 return path->dentry;
334}
335
336static struct vfsmount *autofs4_d_automount(struct path *path)
337{
338 struct dentry *dentry = path->dentry;
339 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
340 struct autofs_info *ino = autofs4_dentry_ino(dentry);
341 int status;
342
343 pr_debug("dentry=%p %pd\n", dentry, dentry);
344
345 /* The daemon never triggers a mount. */
346 if (autofs4_oz_mode(sbi))
347 return NULL;
348
349 /*
350 * If an expire request is pending everyone must wait.
351 * If the expire fails we're still mounted so continue
352 * the follow and return. A return of -EAGAIN (which only
353 * happens with indirect mounts) means the expire completed
354 * and the directory was removed, so just go ahead and try
355 * the mount.
356 */
357 status = do_expire_wait(dentry, 0);
358 if (status && status != -EAGAIN)
359 return NULL;
360
361 /* Callback to the daemon to perform the mount or wait */
362 spin_lock(&sbi->fs_lock);
363 if (ino->flags & AUTOFS_INF_PENDING) {
364 spin_unlock(&sbi->fs_lock);
365 status = autofs4_mount_wait(dentry, 0);
366 if (status)
367 return ERR_PTR(status);
368 goto done;
369 }
370
371 /*
372 * If the dentry is a symlink it's equivalent to a directory
373 * having d_mountpoint() true, so there's no need to call back
374 * to the daemon.
375 */
376 if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
377 spin_unlock(&sbi->fs_lock);
378 goto done;
379 }
380
381 if (!d_mountpoint(dentry)) {
382 /*
383 * It's possible that user space hasn't removed directories
384 * after umounting a rootless multi-mount, although it
385 * should. For v5 have_submounts() is sufficient to handle
386 * this because the leaves of the directory tree under the
387 * mount never trigger mounts themselves (they have an autofs
388 * trigger mount mounted on them). But v4 pseudo direct mounts
389 * do need the leaves to trigger mounts. In this case we
390 * have no choice but to use the list_empty() check and
391 * require user space behave.
392 */
393 if (sbi->version > 4) {
394 if (have_submounts(dentry)) {
395 spin_unlock(&sbi->fs_lock);
396 goto done;
397 }
398 } else {
399 if (!simple_empty(dentry)) {
400 spin_unlock(&sbi->fs_lock);
401 goto done;
402 }
403 }
404 ino->flags |= AUTOFS_INF_PENDING;
405 spin_unlock(&sbi->fs_lock);
406 status = autofs4_mount_wait(dentry, 0);
407 spin_lock(&sbi->fs_lock);
408 ino->flags &= ~AUTOFS_INF_PENDING;
409 if (status) {
410 spin_unlock(&sbi->fs_lock);
411 return ERR_PTR(status);
412 }
413 }
414 spin_unlock(&sbi->fs_lock);
415done:
416 /* Mount succeeded, check if we ended up with a new dentry */
417 dentry = autofs4_mountpoint_changed(path);
418 if (!dentry)
419 return ERR_PTR(-ENOENT);
420
421 return NULL;
422}
423
424static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
425{
426 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
427 struct autofs_info *ino = autofs4_dentry_ino(dentry);
428 int status;
429
430 pr_debug("dentry=%p %pd\n", dentry, dentry);
431
432 /* The daemon never waits. */
433 if (autofs4_oz_mode(sbi)) {
434 if (!d_mountpoint(dentry))
435 return -EISDIR;
436 return 0;
437 }
438
439 /* Wait for pending expires */
440 if (do_expire_wait(dentry, rcu_walk) == -ECHILD)
441 return -ECHILD;
442
443 /*
444 * This dentry may be under construction so wait on mount
445 * completion.
446 */
447 status = autofs4_mount_wait(dentry, rcu_walk);
448 if (status)
449 return status;
450
451 if (rcu_walk) {
452 /* We don't need fs_lock in rcu_walk mode,
453 * just testing 'AUTOFS_INFO_NO_RCU' is enough.
454 * simple_empty() takes a spinlock, so leave it
455 * to last.
456 * We only return -EISDIR when certain this isn't
457 * a mount-trap.
458 */
459 struct inode *inode;
460
461 if (ino->flags & (AUTOFS_INF_EXPIRING | AUTOFS_INF_NO_RCU))
462 return 0;
463 if (d_mountpoint(dentry))
464 return 0;
465 inode = d_inode_rcu(dentry);
466 if (inode && S_ISLNK(inode->i_mode))
467 return -EISDIR;
468 if (list_empty(&dentry->d_subdirs))
469 return 0;
470 if (!simple_empty(dentry))
471 return -EISDIR;
472 return 0;
473 }
474
475 spin_lock(&sbi->fs_lock);
476 /*
477 * If the dentry has been selected for expire while we slept
478 * on the lock then it might go away. We'll deal with that in
479 * ->d_automount() and wait on a new mount if the expire
480 * succeeds or return here if it doesn't (since there's no
481 * mount to follow with a rootless multi-mount).
482 */
483 if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
484 /*
485 * Any needed mounting has been completed and the path
486 * updated so check if this is a rootless multi-mount so
487 * we can avoid needless calls ->d_automount() and avoid
488 * an incorrect ELOOP error return.
489 */
490 if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
491 (d_really_is_positive(dentry) && d_is_symlink(dentry)))
492 status = -EISDIR;
493 }
494 spin_unlock(&sbi->fs_lock);
495
496 return status;
497}
498
499/* Lookups in the root directory */
500static struct dentry *autofs4_lookup(struct inode *dir,
501 struct dentry *dentry, unsigned int flags)
502{
503 struct autofs_sb_info *sbi;
504 struct autofs_info *ino;
505 struct dentry *active;
506
507 pr_debug("name = %pd\n", dentry);
508
509 /* File name too long to exist */
510 if (dentry->d_name.len > NAME_MAX)
511 return ERR_PTR(-ENAMETOOLONG);
512
513 sbi = autofs4_sbi(dir->i_sb);
514
515 pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
516 current->pid, task_pgrp_nr(current), sbi->catatonic,
517 autofs4_oz_mode(sbi));
518
519 active = autofs4_lookup_active(dentry);
520 if (active)
521 return active;
522 else {
523 /*
524 * A dentry that is not within the root can never trigger a
525 * mount operation, unless the directory already exists, so we
526 * can return fail immediately. The daemon however does need
527 * to create directories within the file system.
528 */
529 if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
530 return ERR_PTR(-ENOENT);
531
532 /* Mark entries in the root as mount triggers */
533 if (IS_ROOT(dentry->d_parent) &&
534 autofs_type_indirect(sbi->type))
535 __managed_dentry_set_managed(dentry);
536
537 ino = autofs4_new_ino(sbi);
538 if (!ino)
539 return ERR_PTR(-ENOMEM);
540
541 dentry->d_fsdata = ino;
542 ino->dentry = dentry;
543
544 autofs4_add_active(dentry);
545 }
546 return NULL;
547}
548
549static int autofs4_dir_symlink(struct inode *dir,
550 struct dentry *dentry,
551 const char *symname)
552{
553 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
554 struct autofs_info *ino = autofs4_dentry_ino(dentry);
555 struct autofs_info *p_ino;
556 struct inode *inode;
557 size_t size = strlen(symname);
558 char *cp;
559
560 pr_debug("%s <- %pd\n", symname, dentry);
561
562 if (!autofs4_oz_mode(sbi))
563 return -EACCES;
564
565 BUG_ON(!ino);
566
567 autofs4_clean_ino(ino);
568
569 autofs4_del_active(dentry);
570
571 cp = kmalloc(size + 1, GFP_KERNEL);
572 if (!cp)
573 return -ENOMEM;
574
575 strcpy(cp, symname);
576
577 inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555);
578 if (!inode) {
579 kfree(cp);
580 if (!dentry->d_fsdata)
581 kfree(ino);
582 return -ENOMEM;
583 }
584 inode->i_private = cp;
585 inode->i_size = size;
586 d_add(dentry, inode);
587
588 dget(dentry);
589 atomic_inc(&ino->count);
590 p_ino = autofs4_dentry_ino(dentry->d_parent);
591 if (p_ino && !IS_ROOT(dentry))
592 atomic_inc(&p_ino->count);
593
594 dir->i_mtime = CURRENT_TIME;
595
596 return 0;
597}
598
599/*
600 * NOTE!
601 *
602 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
603 * that the file no longer exists. However, doing that means that the
604 * VFS layer can turn the dentry into a negative dentry. We don't want
605 * this, because the unlink is probably the result of an expire.
606 * We simply d_drop it and add it to a expiring list in the super block,
607 * which allows the dentry lookup to check for an incomplete expire.
608 *
609 * If a process is blocked on the dentry waiting for the expire to finish,
610 * it will invalidate the dentry and try to mount with a new one.
611 *
612 * Also see autofs4_dir_rmdir()..
613 */
614static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
615{
616 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
617 struct autofs_info *ino = autofs4_dentry_ino(dentry);
618 struct autofs_info *p_ino;
619
620 /* This allows root to remove symlinks */
621 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
622 return -EPERM;
623
624 if (atomic_dec_and_test(&ino->count)) {
625 p_ino = autofs4_dentry_ino(dentry->d_parent);
626 if (p_ino && !IS_ROOT(dentry))
627 atomic_dec(&p_ino->count);
628 }
629 dput(ino->dentry);
630
631 d_inode(dentry)->i_size = 0;
632 clear_nlink(d_inode(dentry));
633
634 dir->i_mtime = CURRENT_TIME;
635
636 spin_lock(&sbi->lookup_lock);
637 __autofs4_add_expiring(dentry);
638 d_drop(dentry);
639 spin_unlock(&sbi->lookup_lock);
640
641 return 0;
642}
643
644/*
645 * Version 4 of autofs provides a pseudo direct mount implementation
646 * that relies on directories at the leaves of a directory tree under
647 * an indirect mount to trigger mounts. To allow for this we need to
648 * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
649 * of the directory tree. There is no need to clear the automount flag
650 * following a mount or restore it after an expire because these mounts
651 * are always covered. However, it is necessary to ensure that these
652 * flags are clear on non-empty directories to avoid unnecessary calls
653 * during path walks.
654 */
655static void autofs_set_leaf_automount_flags(struct dentry *dentry)
656{
657 struct dentry *parent;
658
659 /* root and dentrys in the root are already handled */
660 if (IS_ROOT(dentry->d_parent))
661 return;
662
663 managed_dentry_set_managed(dentry);
664
665 parent = dentry->d_parent;
666 /* only consider parents below dentrys in the root */
667 if (IS_ROOT(parent->d_parent))
668 return;
669 managed_dentry_clear_managed(parent);
670}
671
672static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
673{
674 struct list_head *d_child;
675 struct dentry *parent;
676
677 /* flags for dentrys in the root are handled elsewhere */
678 if (IS_ROOT(dentry->d_parent))
679 return;
680
681 managed_dentry_clear_managed(dentry);
682
683 parent = dentry->d_parent;
684 /* only consider parents below dentrys in the root */
685 if (IS_ROOT(parent->d_parent))
686 return;
687 d_child = &dentry->d_child;
688 /* Set parent managed if it's becoming empty */
689 if (d_child->next == &parent->d_subdirs &&
690 d_child->prev == &parent->d_subdirs)
691 managed_dentry_set_managed(parent);
692}
693
694static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
695{
696 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
697 struct autofs_info *ino = autofs4_dentry_ino(dentry);
698 struct autofs_info *p_ino;
699
700 pr_debug("dentry %p, removing %pd\n", dentry, dentry);
701
702 if (!autofs4_oz_mode(sbi))
703 return -EACCES;
704
705 spin_lock(&sbi->lookup_lock);
706 if (!simple_empty(dentry)) {
707 spin_unlock(&sbi->lookup_lock);
708 return -ENOTEMPTY;
709 }
710 __autofs4_add_expiring(dentry);
711 d_drop(dentry);
712 spin_unlock(&sbi->lookup_lock);
713
714 if (sbi->version < 5)
715 autofs_clear_leaf_automount_flags(dentry);
716
717 if (atomic_dec_and_test(&ino->count)) {
718 p_ino = autofs4_dentry_ino(dentry->d_parent);
719 if (p_ino && dentry->d_parent != dentry)
720 atomic_dec(&p_ino->count);
721 }
722 dput(ino->dentry);
723 d_inode(dentry)->i_size = 0;
724 clear_nlink(d_inode(dentry));
725
726 if (dir->i_nlink)
727 drop_nlink(dir);
728
729 return 0;
730}
731
732static int autofs4_dir_mkdir(struct inode *dir,
733 struct dentry *dentry, umode_t mode)
734{
735 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
736 struct autofs_info *ino = autofs4_dentry_ino(dentry);
737 struct autofs_info *p_ino;
738 struct inode *inode;
739
740 if (!autofs4_oz_mode(sbi))
741 return -EACCES;
742
743 pr_debug("dentry %p, creating %pd\n", dentry, dentry);
744
745 BUG_ON(!ino);
746
747 autofs4_clean_ino(ino);
748
749 autofs4_del_active(dentry);
750
751 inode = autofs4_get_inode(dir->i_sb, S_IFDIR | 0555);
752 if (!inode)
753 return -ENOMEM;
754 d_add(dentry, inode);
755
756 if (sbi->version < 5)
757 autofs_set_leaf_automount_flags(dentry);
758
759 dget(dentry);
760 atomic_inc(&ino->count);
761 p_ino = autofs4_dentry_ino(dentry->d_parent);
762 if (p_ino && !IS_ROOT(dentry))
763 atomic_inc(&p_ino->count);
764 inc_nlink(dir);
765 dir->i_mtime = CURRENT_TIME;
766
767 return 0;
768}
769
770/* Get/set timeout ioctl() operation */
771#ifdef CONFIG_COMPAT
772static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi,
773 compat_ulong_t __user *p)
774{
775 unsigned long ntimeout;
776 int rv;
777
778 rv = get_user(ntimeout, p);
779 if (rv)
780 goto error;
781
782 rv = put_user(sbi->exp_timeout/HZ, p);
783 if (rv)
784 goto error;
785
786 if (ntimeout > UINT_MAX/HZ)
787 sbi->exp_timeout = 0;
788 else
789 sbi->exp_timeout = ntimeout * HZ;
790
791 return 0;
792error:
793 return rv;
794}
795#endif
796
797static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
798 unsigned long __user *p)
799{
800 unsigned long ntimeout;
801 int rv;
802
803 rv = get_user(ntimeout, p);
804 if (rv)
805 goto error;
806
807 rv = put_user(sbi->exp_timeout/HZ, p);
808 if (rv)
809 goto error;
810
811 if (ntimeout > ULONG_MAX/HZ)
812 sbi->exp_timeout = 0;
813 else
814 sbi->exp_timeout = ntimeout * HZ;
815
816 return 0;
817error:
818 return rv;
819}
820
821/* Return protocol version */
822static inline int autofs4_get_protover(struct autofs_sb_info *sbi,
823 int __user *p)
824{
825 return put_user(sbi->version, p);
826}
827
828/* Return protocol sub version */
829static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi,
830 int __user *p)
831{
832 return put_user(sbi->sub_version, p);
833}
834
835/*
836* Tells the daemon whether it can umount the autofs mount.
837*/
838static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
839{
840 int status = 0;
841
842 if (may_umount(mnt))
843 status = 1;
844
845 pr_debug("returning %d\n", status);
846
847 status = put_user(status, p);
848
849 return status;
850}
851
852/* Identify autofs4_dentries - this is so we can tell if there's
853 * an extra dentry refcount or not. We only hold a refcount on the
854 * dentry if its non-negative (ie, d_inode != NULL)
855 */
856int is_autofs4_dentry(struct dentry *dentry)
857{
858 return dentry && d_really_is_positive(dentry) &&
859 dentry->d_op == &autofs4_dentry_operations &&
860 dentry->d_fsdata != NULL;
861}
862
863/*
864 * ioctl()'s on the root directory is the chief method for the daemon to
865 * generate kernel reactions
866 */
867static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
868 unsigned int cmd, unsigned long arg)
869{
870 struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
871 void __user *p = (void __user *)arg;
872
873 pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
874 cmd, arg, sbi, task_pgrp_nr(current));
875
876 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
877 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
878 return -ENOTTY;
879
880 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
881 return -EPERM;
882
883 switch (cmd) {
884 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
885 return autofs4_wait_release(sbi, (autofs_wqt_t) arg, 0);
886 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
887 return autofs4_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
888 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
889 autofs4_catatonic_mode(sbi);
890 return 0;
891 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
892 return autofs4_get_protover(sbi, p);
893 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
894 return autofs4_get_protosubver(sbi, p);
895 case AUTOFS_IOC_SETTIMEOUT:
896 return autofs4_get_set_timeout(sbi, p);
897#ifdef CONFIG_COMPAT
898 case AUTOFS_IOC_SETTIMEOUT32:
899 return autofs4_compat_get_set_timeout(sbi, p);
900#endif
901
902 case AUTOFS_IOC_ASKUMOUNT:
903 return autofs4_ask_umount(filp->f_path.mnt, p);
904
905 /* return a single thing to expire */
906 case AUTOFS_IOC_EXPIRE:
907 return autofs4_expire_run(inode->i_sb,
908 filp->f_path.mnt, sbi, p);
909 /* same as above, but can send multiple expires through pipe */
910 case AUTOFS_IOC_EXPIRE_MULTI:
911 return autofs4_expire_multi(inode->i_sb,
912 filp->f_path.mnt, sbi, p);
913
914 default:
915 return -EINVAL;
916 }
917}
918
919static long autofs4_root_ioctl(struct file *filp,
920 unsigned int cmd, unsigned long arg)
921{
922 struct inode *inode = file_inode(filp);
923
924 return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
925}
926
927#ifdef CONFIG_COMPAT
928static long autofs4_root_compat_ioctl(struct file *filp,
929 unsigned int cmd, unsigned long arg)
930{
931 struct inode *inode = file_inode(filp);
932 int ret;
933
934 if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
935 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
936 else
937 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd,
938 (unsigned long) compat_ptr(arg));
939
940 return ret;
941}
942#endif