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Linux 2.6.26-rc5
[linux-2.6/openmoko-kernel/knife-kernel.git] / fs / autofs4 / root.c
blobedf5b6bddb528a43bb85e51eb834ecbdb14a7877
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 int autofs4_dir_close(struct inode *inode, struct file *file);
29 static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
30 static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
31 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
32 static void *autofs4_follow_link(struct dentry *, struct nameidata *);
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 = autofs4_root_readdir,
39 .ioctl = autofs4_root_ioctl,
40 };
41
42 const struct file_operations autofs4_dir_operations = {
43 .open = autofs4_dir_open,
44 .release = autofs4_dir_close,
45 .read = generic_read_dir,
46 .readdir = autofs4_dir_readdir,
47 };
48
49 const struct inode_operations autofs4_indirect_root_inode_operations = {
50 .lookup = autofs4_lookup,
51 .unlink = autofs4_dir_unlink,
52 .symlink = autofs4_dir_symlink,
53 .mkdir = autofs4_dir_mkdir,
54 .rmdir = autofs4_dir_rmdir,
55 };
56
57 const struct inode_operations autofs4_direct_root_inode_operations = {
58 .lookup = autofs4_lookup,
59 .unlink = autofs4_dir_unlink,
60 .mkdir = autofs4_dir_mkdir,
61 .rmdir = autofs4_dir_rmdir,
62 .follow_link = autofs4_follow_link,
63 };
64
65 const struct inode_operations autofs4_dir_inode_operations = {
66 .lookup = autofs4_lookup,
67 .unlink = autofs4_dir_unlink,
68 .symlink = autofs4_dir_symlink,
69 .mkdir = autofs4_dir_mkdir,
70 .rmdir = autofs4_dir_rmdir,
71 };
72
73 static int autofs4_root_readdir(struct file *file, void *dirent,
74 filldir_t filldir)
75 {
76 struct autofs_sb_info *sbi = autofs4_sbi(file->f_path.dentry->d_sb);
77 int oz_mode = autofs4_oz_mode(sbi);
78
79 DPRINTK("called, filp->f_pos = %lld", file->f_pos);
80
81 /*
82 * Don't set reghost flag if:
83 * 1) f_pos is larger than zero -- we've already been here.
84 * 2) we haven't even enabled reghosting in the 1st place.
85 * 3) this is the daemon doing a readdir
86 */
87 if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
88 sbi->needs_reghost = 1;
89
90 DPRINTK("needs_reghost = %d", sbi->needs_reghost);
91
92 return dcache_readdir(file, dirent, filldir);
93 }
94
95 static int autofs4_dir_open(struct inode *inode, struct file *file)
96 {
97 struct dentry *dentry = file->f_path.dentry;
98 struct vfsmount *mnt = file->f_path.mnt;
99 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
100 struct dentry *cursor;
101 int status;
102
103 status = dcache_dir_open(inode, file);
104 if (status)
105 goto out;
106
107 cursor = file->private_data;
108 cursor->d_fsdata = NULL;
109
110 DPRINTK("file=%p dentry=%p %.*s",
111 file, dentry, dentry->d_name.len, dentry->d_name.name);
112
113 if (autofs4_oz_mode(sbi))
114 goto out;
115
116 if (autofs4_ispending(dentry)) {
117 DPRINTK("dentry busy");
118 dcache_dir_close(inode, file);
119 status = -EBUSY;
120 goto out;
121 }
122
123 status = -ENOENT;
124 if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
125 struct nameidata nd;
126 int empty, ret;
127
128 /* In case there are stale directory dentrys from a failed mount */
129 spin_lock(&dcache_lock);
130 empty = list_empty(&dentry->d_subdirs);
131 spin_unlock(&dcache_lock);
132
133 if (!empty)
134 d_invalidate(dentry);
135
136 nd.flags = LOOKUP_DIRECTORY;
137 ret = (dentry->d_op->d_revalidate)(dentry, &nd);
138
139 if (ret <= 0) {
140 if (ret < 0)
141 status = ret;
142 dcache_dir_close(inode, file);
143 goto out;
144 }
145 }
146
147 if (d_mountpoint(dentry)) {
148 struct file *fp = NULL;
149 struct path fp_path = { .dentry = dentry, .mnt = mnt };
150
151 path_get(&fp_path);
152
153 if (!autofs4_follow_mount(&fp_path.mnt, &fp_path.dentry)) {
154 path_put(&fp_path);
155 dcache_dir_close(inode, file);
156 goto out;
157 }
158
159 fp = dentry_open(fp_path.dentry, fp_path.mnt, file->f_flags);
160 status = PTR_ERR(fp);
161 if (IS_ERR(fp)) {
162 dcache_dir_close(inode, file);
163 goto out;
164 }
165 cursor->d_fsdata = fp;
166 }
167 return 0;
168 out:
169 return status;
170 }
171
172 static int autofs4_dir_close(struct inode *inode, struct file *file)
173 {
174 struct dentry *dentry = file->f_path.dentry;
175 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
176 struct dentry *cursor = file->private_data;
177 int status = 0;
178
179 DPRINTK("file=%p dentry=%p %.*s",
180 file, dentry, dentry->d_name.len, dentry->d_name.name);
181
182 if (autofs4_oz_mode(sbi))
183 goto out;
184
185 if (autofs4_ispending(dentry)) {
186 DPRINTK("dentry busy");
187 status = -EBUSY;
188 goto out;
189 }
190
191 if (d_mountpoint(dentry)) {
192 struct file *fp = cursor->d_fsdata;
193 if (!fp) {
194 status = -ENOENT;
195 goto out;
196 }
197 filp_close(fp, current->files);
198 }
199 out:
200 dcache_dir_close(inode, file);
201 return status;
202 }
203
204 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
205 {
206 struct dentry *dentry = file->f_path.dentry;
207 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
208 struct dentry *cursor = file->private_data;
209 int status;
210
211 DPRINTK("file=%p dentry=%p %.*s",
212 file, dentry, dentry->d_name.len, dentry->d_name.name);
213
214 if (autofs4_oz_mode(sbi))
215 goto out;
216
217 if (autofs4_ispending(dentry)) {
218 DPRINTK("dentry busy");
219 return -EBUSY;
220 }
221
222 if (d_mountpoint(dentry)) {
223 struct file *fp = cursor->d_fsdata;
224
225 if (!fp)
226 return -ENOENT;
227
228 if (!fp->f_op || !fp->f_op->readdir)
229 goto out;
230
231 status = vfs_readdir(fp, filldir, dirent);
232 file->f_pos = fp->f_pos;
233 if (status)
234 autofs4_copy_atime(file, fp);
235 return status;
236 }
237 out:
238 return dcache_readdir(file, dirent, filldir);
239 }
240
241 static int try_to_fill_dentry(struct dentry *dentry, int flags)
242 {
243 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
244 struct autofs_info *ino = autofs4_dentry_ino(dentry);
245 struct dentry *new;
246 int status;
247
248 /* Block on any pending expiry here; invalidate the dentry
249 when expiration is done to trigger mount request with a new
250 dentry */
251 if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
252 DPRINTK("waiting for expire %p name=%.*s",
253 dentry, dentry->d_name.len, dentry->d_name.name);
254
255 status = autofs4_wait(sbi, dentry, NFY_NONE);
256
257 DPRINTK("expire done status=%d", status);
258
259 /*
260 * If the directory still exists the mount request must
261 * continue otherwise it can't be followed at the right
262 * time during the walk.
263 */
264 status = d_invalidate(dentry);
265 if (status != -EBUSY)
266 return -EAGAIN;
267 }
268
269 DPRINTK("dentry=%p %.*s ino=%p",
270 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
271
272 /*
273 * Wait for a pending mount, triggering one if there
274 * isn't one already
275 */
276 if (dentry->d_inode == NULL) {
277 DPRINTK("waiting for mount name=%.*s",
278 dentry->d_name.len, dentry->d_name.name);
279
280 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
281
282 DPRINTK("mount done status=%d", status);
283
284 /* Turn this into a real negative dentry? */
285 if (status == -ENOENT) {
286 spin_lock(&dentry->d_lock);
287 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
288 spin_unlock(&dentry->d_lock);
289 return status;
290 } else if (status) {
291 /* Return a negative dentry, but leave it "pending" */
292 return status;
293 }
294 /* Trigger mount for path component or follow link */
295 } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
296 current->link_count) {
297 DPRINTK("waiting for mount name=%.*s",
298 dentry->d_name.len, dentry->d_name.name);
299
300 spin_lock(&dentry->d_lock);
301 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
302 spin_unlock(&dentry->d_lock);
303 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
304
305 DPRINTK("mount done status=%d", status);
306
307 if (status) {
308 spin_lock(&dentry->d_lock);
309 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
310 spin_unlock(&dentry->d_lock);
311 return status;
312 }
313 }
314
315 /* Initialize expiry counter after successful mount */
316 if (ino)
317 ino->last_used = jiffies;
318
319 spin_lock(&dentry->d_lock);
320 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
321 spin_unlock(&dentry->d_lock);
322
323 /*
324 * The dentry that is passed in from lookup may not be the one
325 * we end up using, as mkdir can create a new one. If this
326 * happens, and another process tries the lookup at the same time,
327 * it will set the PENDING flag on this new dentry, but add itself
328 * to our waitq. Then, if after the lookup succeeds, the first
329 * process that requested the mount performs another lookup of the
330 * same directory, it will show up as still pending! So, we need
331 * to redo the lookup here and clear pending on that dentry.
332 */
333 if (d_unhashed(dentry)) {
334 new = d_lookup(dentry->d_parent, &dentry->d_name);
335 if (new) {
336 spin_lock(&new->d_lock);
337 new->d_flags &= ~DCACHE_AUTOFS_PENDING;
338 spin_unlock(&new->d_lock);
339 dput(new);
340 }
341 }
342
343 return 0;
344 }
345
346 /* For autofs direct mounts the follow link triggers the mount */
347 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
348 {
349 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
350 struct autofs_info *ino = autofs4_dentry_ino(dentry);
351 int oz_mode = autofs4_oz_mode(sbi);
352 unsigned int lookup_type;
353 int status;
354
355 DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
356 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
357 nd->flags);
358
359 /* If it's our master or we shouldn't trigger a mount we're done */
360 lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
361 if (oz_mode || !lookup_type)
362 goto done;
363
364 /* If an expire request is pending wait for it. */
365 if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
366 DPRINTK("waiting for active request %p name=%.*s",
367 dentry, dentry->d_name.len, dentry->d_name.name);
368
369 status = autofs4_wait(sbi, dentry, NFY_NONE);
370
371 DPRINTK("request done status=%d", status);
372 }
373
374 /*
375 * If the dentry contains directories then it is an
376 * autofs multi-mount with no root mount offset. So
377 * don't try to mount it again.
378 */
379 spin_lock(&dcache_lock);
380 if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
381 spin_unlock(&dcache_lock);
382
383 status = try_to_fill_dentry(dentry, 0);
384 if (status)
385 goto out_error;
386
387 /*
388 * The mount succeeded but if there is no root mount
389 * it must be an autofs multi-mount with no root offset
390 * so we don't need to follow the mount.
391 */
392 if (d_mountpoint(dentry)) {
393 if (!autofs4_follow_mount(&nd->path.mnt,
394 &nd->path.dentry)) {
395 status = -ENOENT;
396 goto out_error;
397 }
398 }
399
400 goto done;
401 }
402 spin_unlock(&dcache_lock);
403
404 done:
405 return NULL;
406
407 out_error:
408 path_put(&nd->path);
409 return ERR_PTR(status);
410 }
411
412 /*
413 * Revalidate is called on every cache lookup. Some of those
414 * cache lookups may actually happen while the dentry is not
415 * yet completely filled in, and revalidate has to delay such
416 * lookups..
417 */
418 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
419 {
420 struct inode *dir = dentry->d_parent->d_inode;
421 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
422 int oz_mode = autofs4_oz_mode(sbi);
423 int flags = nd ? nd->flags : 0;
424 int status = 1;
425
426 /* Pending dentry */
427 if (autofs4_ispending(dentry)) {
428 /* The daemon never causes a mount to trigger */
429 if (oz_mode)
430 return 1;
431
432 /*
433 * A zero status is success otherwise we have a
434 * negative error code.
435 */
436 status = try_to_fill_dentry(dentry, flags);
437 if (status == 0)
438 return 1;
439
440 /*
441 * A status of EAGAIN here means that the dentry has gone
442 * away while waiting for an expire to complete. If we are
443 * racing with expire lookup will wait for it so this must
444 * be a revalidate and we need to send it to lookup.
445 */
446 if (status == -EAGAIN)
447 return 0;
448
449 return status;
450 }
451
452 /* Negative dentry.. invalidate if "old" */
453 if (dentry->d_inode == NULL)
454 return 0;
455
456 /* Check for a non-mountpoint directory with no contents */
457 spin_lock(&dcache_lock);
458 if (S_ISDIR(dentry->d_inode->i_mode) &&
459 !d_mountpoint(dentry) &&
460 __simple_empty(dentry)) {
461 DPRINTK("dentry=%p %.*s, emptydir",
462 dentry, dentry->d_name.len, dentry->d_name.name);
463 spin_unlock(&dcache_lock);
464 /* The daemon never causes a mount to trigger */
465 if (oz_mode)
466 return 1;
467
468 /*
469 * A zero status is success otherwise we have a
470 * negative error code.
471 */
472 status = try_to_fill_dentry(dentry, flags);
473 if (status == 0)
474 return 1;
475
476 return status;
477 }
478 spin_unlock(&dcache_lock);
479
480 return 1;
481 }
482
483 void autofs4_dentry_release(struct dentry *de)
484 {
485 struct autofs_info *inf;
486
487 DPRINTK("releasing %p", de);
488
489 inf = autofs4_dentry_ino(de);
490 de->d_fsdata = NULL;
491
492 if (inf) {
493 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
494
495 if (sbi) {
496 spin_lock(&sbi->rehash_lock);
497 if (!list_empty(&inf->rehash))
498 list_del(&inf->rehash);
499 spin_unlock(&sbi->rehash_lock);
500 }
501
502 inf->dentry = NULL;
503 inf->inode = NULL;
504
505 autofs4_free_ino(inf);
506 }
507 }
508
509 /* For dentries of directories in the root dir */
510 static struct dentry_operations autofs4_root_dentry_operations = {
511 .d_revalidate = autofs4_revalidate,
512 .d_release = autofs4_dentry_release,
513 };
514
515 /* For other dentries */
516 static struct dentry_operations autofs4_dentry_operations = {
517 .d_revalidate = autofs4_revalidate,
518 .d_release = autofs4_dentry_release,
519 };
520
521 static struct dentry *autofs4_lookup_unhashed(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
522 {
523 unsigned int len = name->len;
524 unsigned int hash = name->hash;
525 const unsigned char *str = name->name;
526 struct list_head *p, *head;
527
528 spin_lock(&dcache_lock);
529 spin_lock(&sbi->rehash_lock);
530 head = &sbi->rehash_list;
531 list_for_each(p, head) {
532 struct autofs_info *ino;
533 struct dentry *dentry;
534 struct qstr *qstr;
535
536 ino = list_entry(p, struct autofs_info, rehash);
537 dentry = ino->dentry;
538
539 spin_lock(&dentry->d_lock);
540
541 /* Bad luck, we've already been dentry_iput */
542 if (!dentry->d_inode)
543 goto next;
544
545 qstr = &dentry->d_name;
546
547 if (dentry->d_name.hash != hash)
548 goto next;
549 if (dentry->d_parent != parent)
550 goto next;
551
552 if (qstr->len != len)
553 goto next;
554 if (memcmp(qstr->name, str, len))
555 goto next;
556
557 if (d_unhashed(dentry)) {
558 struct inode *inode = dentry->d_inode;
559
560 ino = autofs4_dentry_ino(dentry);
561 list_del_init(&ino->rehash);
562 dget(dentry);
563 /*
564 * Make the rehashed dentry negative so the VFS
565 * behaves as it should.
566 */
567 if (inode) {
568 dentry->d_inode = NULL;
569 list_del_init(&dentry->d_alias);
570 spin_unlock(&dentry->d_lock);
571 spin_unlock(&sbi->rehash_lock);
572 spin_unlock(&dcache_lock);
573 iput(inode);
574 return dentry;
575 }
576 spin_unlock(&dentry->d_lock);
577 spin_unlock(&sbi->rehash_lock);
578 spin_unlock(&dcache_lock);
579 return dentry;
580 }
581 next:
582 spin_unlock(&dentry->d_lock);
583 }
584 spin_unlock(&sbi->rehash_lock);
585 spin_unlock(&dcache_lock);
586
587 return NULL;
588 }
589
590 /* Lookups in the root directory */
591 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
592 {
593 struct autofs_sb_info *sbi;
594 struct dentry *unhashed;
595 int oz_mode;
596
597 DPRINTK("name = %.*s",
598 dentry->d_name.len, dentry->d_name.name);
599
600 /* File name too long to exist */
601 if (dentry->d_name.len > NAME_MAX)
602 return ERR_PTR(-ENAMETOOLONG);
603
604 sbi = autofs4_sbi(dir->i_sb);
605 oz_mode = autofs4_oz_mode(sbi);
606
607 DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
608 current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
609
610 unhashed = autofs4_lookup_unhashed(sbi, dentry->d_parent, &dentry->d_name);
611 if (!unhashed) {
612 /*
613 * Mark the dentry incomplete but don't hash it. We do this
614 * to serialize our inode creation operations (symlink and
615 * mkdir) which prevents deadlock during the callback to
616 * the daemon. Subsequent user space lookups for the same
617 * dentry are placed on the wait queue while the daemon
618 * itself is allowed passage unresticted so the create
619 * operation itself can then hash the dentry. Finally,
620 * we check for the hashed dentry and return the newly
621 * hashed dentry.
622 */
623 dentry->d_op = &autofs4_root_dentry_operations;
624
625 dentry->d_fsdata = NULL;
626 d_instantiate(dentry, NULL);
627 } else {
628 struct autofs_info *ino = autofs4_dentry_ino(unhashed);
629 DPRINTK("rehash %p with %p", dentry, unhashed);
630 /*
631 * If we are racing with expire the request might not
632 * be quite complete but the directory has been removed
633 * so it must have been successful, so just wait for it.
634 * We need to ensure the AUTOFS_INF_EXPIRING flag is clear
635 * before continuing as revalidate may fail when calling
636 * try_to_fill_dentry (returning EAGAIN) if we don't.
637 */
638 while (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
639 DPRINTK("wait for incomplete expire %p name=%.*s",
640 unhashed, unhashed->d_name.len,
641 unhashed->d_name.name);
642 autofs4_wait(sbi, unhashed, NFY_NONE);
643 DPRINTK("request completed");
644 }
645 dentry = unhashed;
646 }
647
648 if (!oz_mode) {
649 spin_lock(&dentry->d_lock);
650 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
651 spin_unlock(&dentry->d_lock);
652 }
653
654 if (dentry->d_op && dentry->d_op->d_revalidate) {
655 mutex_unlock(&dir->i_mutex);
656 (dentry->d_op->d_revalidate)(dentry, nd);
657 mutex_lock(&dir->i_mutex);
658 }
659
660 /*
661 * If we are still pending, check if we had to handle
662 * a signal. If so we can force a restart..
663 */
664 if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
665 /* See if we were interrupted */
666 if (signal_pending(current)) {
667 sigset_t *sigset = &current->pending.signal;
668 if (sigismember (sigset, SIGKILL) ||
669 sigismember (sigset, SIGQUIT) ||
670 sigismember (sigset, SIGINT)) {
671 if (unhashed)
672 dput(unhashed);
673 return ERR_PTR(-ERESTARTNOINTR);
674 }
675 }
676 spin_lock(&dentry->d_lock);
677 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
678 spin_unlock(&dentry->d_lock);
679 }
680
681 /*
682 * If this dentry is unhashed, then we shouldn't honour this
683 * lookup. Returning ENOENT here doesn't do the right thing
684 * for all system calls, but it should be OK for the operations
685 * we permit from an autofs.
686 */
687 if (!oz_mode && d_unhashed(dentry)) {
688 /*
689 * A user space application can (and has done in the past)
690 * remove and re-create this directory during the callback.
691 * This can leave us with an unhashed dentry, but a
692 * successful mount! So we need to perform another
693 * cached lookup in case the dentry now exists.
694 */
695 struct dentry *parent = dentry->d_parent;
696 struct dentry *new = d_lookup(parent, &dentry->d_name);
697 if (new != NULL)
698 dentry = new;
699 else
700 dentry = ERR_PTR(-ENOENT);
701
702 if (unhashed)
703 dput(unhashed);
704
705 return dentry;
706 }
707
708 if (unhashed)
709 return dentry;
710
711 return NULL;
712 }
713
714 static int autofs4_dir_symlink(struct inode *dir,
715 struct dentry *dentry,
716 const char *symname)
717 {
718 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
719 struct autofs_info *ino = autofs4_dentry_ino(dentry);
720 struct autofs_info *p_ino;
721 struct inode *inode;
722 char *cp;
723
724 DPRINTK("%s <- %.*s", symname,
725 dentry->d_name.len, dentry->d_name.name);
726
727 if (!autofs4_oz_mode(sbi))
728 return -EACCES;
729
730 ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
731 if (ino == NULL)
732 return -ENOSPC;
733
734 ino->size = strlen(symname);
735 ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
736
737 if (cp == NULL) {
738 kfree(ino);
739 return -ENOSPC;
740 }
741
742 strcpy(cp, symname);
743
744 inode = autofs4_get_inode(dir->i_sb, ino);
745 d_add(dentry, inode);
746
747 if (dir == dir->i_sb->s_root->d_inode)
748 dentry->d_op = &autofs4_root_dentry_operations;
749 else
750 dentry->d_op = &autofs4_dentry_operations;
751
752 dentry->d_fsdata = ino;
753 ino->dentry = dget(dentry);
754 atomic_inc(&ino->count);
755 p_ino = autofs4_dentry_ino(dentry->d_parent);
756 if (p_ino && dentry->d_parent != dentry)
757 atomic_inc(&p_ino->count);
758 ino->inode = inode;
759
760 dir->i_mtime = CURRENT_TIME;
761
762 return 0;
763 }
764
765 /*
766 * NOTE!
767 *
768 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
769 * that the file no longer exists. However, doing that means that the
770 * VFS layer can turn the dentry into a negative dentry. We don't want
771 * this, because the unlink is probably the result of an expire.
772 * We simply d_drop it and add it to a rehash candidates list in the
773 * super block, which allows the dentry lookup to reuse it retaining
774 * the flags, such as expire in progress, in case we're racing with expire.
775 *
776 * If a process is blocked on the dentry waiting for the expire to finish,
777 * it will invalidate the dentry and try to mount with a new one.
778 *
779 * Also see autofs4_dir_rmdir()..
780 */
781 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
782 {
783 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
784 struct autofs_info *ino = autofs4_dentry_ino(dentry);
785 struct autofs_info *p_ino;
786
787 /* This allows root to remove symlinks */
788 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
789 return -EACCES;
790
791 if (atomic_dec_and_test(&ino->count)) {
792 p_ino = autofs4_dentry_ino(dentry->d_parent);
793 if (p_ino && dentry->d_parent != dentry)
794 atomic_dec(&p_ino->count);
795 }
796 dput(ino->dentry);
797
798 dentry->d_inode->i_size = 0;
799 clear_nlink(dentry->d_inode);
800
801 dir->i_mtime = CURRENT_TIME;
802
803 spin_lock(&dcache_lock);
804 spin_lock(&sbi->rehash_lock);
805 list_add(&ino->rehash, &sbi->rehash_list);
806 spin_unlock(&sbi->rehash_lock);
807 spin_lock(&dentry->d_lock);
808 __d_drop(dentry);
809 spin_unlock(&dentry->d_lock);
810 spin_unlock(&dcache_lock);
811
812 return 0;
813 }
814
815 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
816 {
817 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
818 struct autofs_info *ino = autofs4_dentry_ino(dentry);
819 struct autofs_info *p_ino;
820
821 DPRINTK("dentry %p, removing %.*s",
822 dentry, dentry->d_name.len, dentry->d_name.name);
823
824 if (!autofs4_oz_mode(sbi))
825 return -EACCES;
826
827 spin_lock(&dcache_lock);
828 if (!list_empty(&dentry->d_subdirs)) {
829 spin_unlock(&dcache_lock);
830 return -ENOTEMPTY;
831 }
832 spin_lock(&sbi->rehash_lock);
833 list_add(&ino->rehash, &sbi->rehash_list);
834 spin_unlock(&sbi->rehash_lock);
835 spin_lock(&dentry->d_lock);
836 __d_drop(dentry);
837 spin_unlock(&dentry->d_lock);
838 spin_unlock(&dcache_lock);
839
840 if (atomic_dec_and_test(&ino->count)) {
841 p_ino = autofs4_dentry_ino(dentry->d_parent);
842 if (p_ino && dentry->d_parent != dentry)
843 atomic_dec(&p_ino->count);
844 }
845 dput(ino->dentry);
846 dentry->d_inode->i_size = 0;
847 clear_nlink(dentry->d_inode);
848
849 if (dir->i_nlink)
850 drop_nlink(dir);
851
852 return 0;
853 }
854
855 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
856 {
857 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
858 struct autofs_info *ino = autofs4_dentry_ino(dentry);
859 struct autofs_info *p_ino;
860 struct inode *inode;
861
862 if (!autofs4_oz_mode(sbi))
863 return -EACCES;
864
865 DPRINTK("dentry %p, creating %.*s",
866 dentry, dentry->d_name.len, dentry->d_name.name);
867
868 ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
869 if (ino == NULL)
870 return -ENOSPC;
871
872 inode = autofs4_get_inode(dir->i_sb, ino);
873 d_add(dentry, inode);
874
875 if (dir == dir->i_sb->s_root->d_inode)
876 dentry->d_op = &autofs4_root_dentry_operations;
877 else
878 dentry->d_op = &autofs4_dentry_operations;
879
880 dentry->d_fsdata = ino;
881 ino->dentry = dget(dentry);
882 atomic_inc(&ino->count);
883 p_ino = autofs4_dentry_ino(dentry->d_parent);
884 if (p_ino && dentry->d_parent != dentry)
885 atomic_inc(&p_ino->count);
886 ino->inode = inode;
887 inc_nlink(dir);
888 dir->i_mtime = CURRENT_TIME;
889
890 return 0;
891 }
892
893 /* Get/set timeout ioctl() operation */
894 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
895 unsigned long __user *p)
896 {
897 int rv;
898 unsigned long ntimeout;
899
900 if ((rv = get_user(ntimeout, p)) ||
901 (rv = put_user(sbi->exp_timeout/HZ, p)))
902 return rv;
903
904 if (ntimeout > ULONG_MAX/HZ)
905 sbi->exp_timeout = 0;
906 else
907 sbi->exp_timeout = ntimeout * HZ;
908
909 return 0;
910 }
911
912 /* Return protocol version */
913 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
914 {
915 return put_user(sbi->version, p);
916 }
917
918 /* Return protocol sub version */
919 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
920 {
921 return put_user(sbi->sub_version, p);
922 }
923
924 /*
925 * Tells the daemon whether we need to reghost or not. Also, clears
926 * the reghost_needed flag.
927 */
928 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
929 {
930 int status;
931
932 DPRINTK("returning %d", sbi->needs_reghost);
933
934 status = put_user(sbi->needs_reghost, p);
935 if (status)
936 return status;
937
938 sbi->needs_reghost = 0;
939 return 0;
940 }
941
942 /*
943 * Enable / Disable reghosting ioctl() operation
944 */
945 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
946 {
947 int status;
948 int val;
949
950 status = get_user(val, p);
951
952 DPRINTK("reghost = %d", val);
953
954 if (status)
955 return status;
956
957 /* turn on/off reghosting, with the val */
958 sbi->reghost_enabled = val;
959 return 0;
960 }
961
962 /*
963 * Tells the daemon whether it can umount the autofs mount.
964 */
965 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
966 {
967 int status = 0;
968
969 if (may_umount(mnt))
970 status = 1;
971
972 DPRINTK("returning %d", status);
973
974 status = put_user(status, p);
975
976 return status;
977 }
978
979 /* Identify autofs4_dentries - this is so we can tell if there's
980 an extra dentry refcount or not. We only hold a refcount on the
981 dentry if its non-negative (ie, d_inode != NULL)
982 */
983 int is_autofs4_dentry(struct dentry *dentry)
984 {
985 return dentry && dentry->d_inode &&
986 (dentry->d_op == &autofs4_root_dentry_operations ||
987 dentry->d_op == &autofs4_dentry_operations) &&
988 dentry->d_fsdata != NULL;
989 }
990
991 /*
992 * ioctl()'s on the root directory is the chief method for the daemon to
993 * generate kernel reactions
994 */
995 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
996 unsigned int cmd, unsigned long arg)
997 {
998 struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
999 void __user *p = (void __user *)arg;
1000
1001 DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
1002 cmd,arg,sbi,task_pgrp_nr(current));
1003
1004 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
1005 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
1006 return -ENOTTY;
1007
1008 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
1009 return -EPERM;
1010
1011 switch(cmd) {
1012 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
1013 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
1014 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
1015 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
1016 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
1017 autofs4_catatonic_mode(sbi);
1018 return 0;
1019 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
1020 return autofs4_get_protover(sbi, p);
1021 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
1022 return autofs4_get_protosubver(sbi, p);
1023 case AUTOFS_IOC_SETTIMEOUT:
1024 return autofs4_get_set_timeout(sbi, p);
1025
1026 case AUTOFS_IOC_TOGGLEREGHOST:
1027 return autofs4_toggle_reghost(sbi, p);
1028 case AUTOFS_IOC_ASKREGHOST:
1029 return autofs4_ask_reghost(sbi, p);
1030
1031 case AUTOFS_IOC_ASKUMOUNT:
1032 return autofs4_ask_umount(filp->f_path.mnt, p);
1033
1034 /* return a single thing to expire */
1035 case AUTOFS_IOC_EXPIRE:
1036 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
1037 /* same as above, but can send multiple expires through pipe */
1038 case AUTOFS_IOC_EXPIRE_MULTI:
1039 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
1040
1041 default:
1042 return -ENOSYS;
1043 }
1044 }
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