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hugetlb: ensure we do not reference a surplus page after handing it to buddy
[linux-2.6/kmemtrace.git] / fs / autofs4 / root.c
bloba54a946a50ae55bc44f04142565834527f07d524
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 vfsmount *fp_mnt = mntget(mnt);
150 struct dentry *fp_dentry = dget(dentry);
151
152 if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
153 dput(fp_dentry);
154 mntput(fp_mnt);
155 dcache_dir_close(inode, file);
156 goto out;
157 }
158
159 fp = dentry_open(fp_dentry, fp_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 int status = 0;
246
247 /* Block on any pending expiry here; invalidate the dentry
248 when expiration is done to trigger mount request with a new
249 dentry */
250 if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
251 DPRINTK("waiting for expire %p name=%.*s",
252 dentry, dentry->d_name.len, dentry->d_name.name);
253
254 status = autofs4_wait(sbi, dentry, NFY_NONE);
255
256 DPRINTK("expire done status=%d", status);
257
258 /*
259 * If the directory still exists the mount request must
260 * continue otherwise it can't be followed at the right
261 * time during the walk.
262 */
263 status = d_invalidate(dentry);
264 if (status != -EBUSY)
265 return -EAGAIN;
266 }
267
268 DPRINTK("dentry=%p %.*s ino=%p",
269 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
270
271 /*
272 * Wait for a pending mount, triggering one if there
273 * isn't one already
274 */
275 if (dentry->d_inode == NULL) {
276 DPRINTK("waiting for mount name=%.*s",
277 dentry->d_name.len, dentry->d_name.name);
278
279 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
280
281 DPRINTK("mount done status=%d", status);
282
283 /* Turn this into a real negative dentry? */
284 if (status == -ENOENT) {
285 spin_lock(&dentry->d_lock);
286 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
287 spin_unlock(&dentry->d_lock);
288 return status;
289 } else if (status) {
290 /* Return a negative dentry, but leave it "pending" */
291 return status;
292 }
293 /* Trigger mount for path component or follow link */
294 } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
295 current->link_count) {
296 DPRINTK("waiting for mount name=%.*s",
297 dentry->d_name.len, dentry->d_name.name);
298
299 spin_lock(&dentry->d_lock);
300 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
301 spin_unlock(&dentry->d_lock);
302 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
303
304 DPRINTK("mount done status=%d", status);
305
306 if (status) {
307 spin_lock(&dentry->d_lock);
308 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
309 spin_unlock(&dentry->d_lock);
310 return status;
311 }
312 }
313
314 /* Initialize expiry counter after successful mount */
315 if (ino)
316 ino->last_used = jiffies;
317
318 spin_lock(&dentry->d_lock);
319 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
320 spin_unlock(&dentry->d_lock);
321 return status;
322 }
323
324 /* For autofs direct mounts the follow link triggers the mount */
325 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
326 {
327 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
328 struct autofs_info *ino = autofs4_dentry_ino(dentry);
329 int oz_mode = autofs4_oz_mode(sbi);
330 unsigned int lookup_type;
331 int status;
332
333 DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
334 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
335 nd->flags);
336
337 /* If it's our master or we shouldn't trigger a mount we're done */
338 lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
339 if (oz_mode || !lookup_type)
340 goto done;
341
342 /* If an expire request is pending wait for it. */
343 if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
344 DPRINTK("waiting for active request %p name=%.*s",
345 dentry, dentry->d_name.len, dentry->d_name.name);
346
347 status = autofs4_wait(sbi, dentry, NFY_NONE);
348
349 DPRINTK("request done status=%d", status);
350 }
351
352 /*
353 * If the dentry contains directories then it is an
354 * autofs multi-mount with no root mount offset. So
355 * don't try to mount it again.
356 */
357 spin_lock(&dcache_lock);
358 if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
359 spin_unlock(&dcache_lock);
360
361 status = try_to_fill_dentry(dentry, 0);
362 if (status)
363 goto out_error;
364
365 /*
366 * The mount succeeded but if there is no root mount
367 * it must be an autofs multi-mount with no root offset
368 * so we don't need to follow the mount.
369 */
370 if (d_mountpoint(dentry)) {
371 if (!autofs4_follow_mount(&nd->path.mnt,
372 &nd->path.dentry)) {
373 status = -ENOENT;
374 goto out_error;
375 }
376 }
377
378 goto done;
379 }
380 spin_unlock(&dcache_lock);
381
382 done:
383 return NULL;
384
385 out_error:
386 path_put(&nd->path);
387 return ERR_PTR(status);
388 }
389
390 /*
391 * Revalidate is called on every cache lookup. Some of those
392 * cache lookups may actually happen while the dentry is not
393 * yet completely filled in, and revalidate has to delay such
394 * lookups..
395 */
396 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
397 {
398 struct inode *dir = dentry->d_parent->d_inode;
399 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
400 int oz_mode = autofs4_oz_mode(sbi);
401 int flags = nd ? nd->flags : 0;
402 int status = 1;
403
404 /* Pending dentry */
405 if (autofs4_ispending(dentry)) {
406 /* The daemon never causes a mount to trigger */
407 if (oz_mode)
408 return 1;
409
410 /*
411 * A zero status is success otherwise we have a
412 * negative error code.
413 */
414 status = try_to_fill_dentry(dentry, flags);
415 if (status == 0)
416 return 1;
417
418 /*
419 * A status of EAGAIN here means that the dentry has gone
420 * away while waiting for an expire to complete. If we are
421 * racing with expire lookup will wait for it so this must
422 * be a revalidate and we need to send it to lookup.
423 */
424 if (status == -EAGAIN)
425 return 0;
426
427 return status;
428 }
429
430 /* Negative dentry.. invalidate if "old" */
431 if (dentry->d_inode == NULL)
432 return 0;
433
434 /* Check for a non-mountpoint directory with no contents */
435 spin_lock(&dcache_lock);
436 if (S_ISDIR(dentry->d_inode->i_mode) &&
437 !d_mountpoint(dentry) &&
438 __simple_empty(dentry)) {
439 DPRINTK("dentry=%p %.*s, emptydir",
440 dentry, dentry->d_name.len, dentry->d_name.name);
441 spin_unlock(&dcache_lock);
442 /* The daemon never causes a mount to trigger */
443 if (oz_mode)
444 return 1;
445
446 /*
447 * A zero status is success otherwise we have a
448 * negative error code.
449 */
450 status = try_to_fill_dentry(dentry, flags);
451 if (status == 0)
452 return 1;
453
454 return status;
455 }
456 spin_unlock(&dcache_lock);
457
458 return 1;
459 }
460
461 void autofs4_dentry_release(struct dentry *de)
462 {
463 struct autofs_info *inf;
464
465 DPRINTK("releasing %p", de);
466
467 inf = autofs4_dentry_ino(de);
468 de->d_fsdata = NULL;
469
470 if (inf) {
471 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
472
473 if (sbi) {
474 spin_lock(&sbi->rehash_lock);
475 if (!list_empty(&inf->rehash))
476 list_del(&inf->rehash);
477 spin_unlock(&sbi->rehash_lock);
478 }
479
480 inf->dentry = NULL;
481 inf->inode = NULL;
482
483 autofs4_free_ino(inf);
484 }
485 }
486
487 /* For dentries of directories in the root dir */
488 static struct dentry_operations autofs4_root_dentry_operations = {
489 .d_revalidate = autofs4_revalidate,
490 .d_release = autofs4_dentry_release,
491 };
492
493 /* For other dentries */
494 static struct dentry_operations autofs4_dentry_operations = {
495 .d_revalidate = autofs4_revalidate,
496 .d_release = autofs4_dentry_release,
497 };
498
499 static struct dentry *autofs4_lookup_unhashed(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
500 {
501 unsigned int len = name->len;
502 unsigned int hash = name->hash;
503 const unsigned char *str = name->name;
504 struct list_head *p, *head;
505
506 spin_lock(&dcache_lock);
507 spin_lock(&sbi->rehash_lock);
508 head = &sbi->rehash_list;
509 list_for_each(p, head) {
510 struct autofs_info *ino;
511 struct dentry *dentry;
512 struct qstr *qstr;
513
514 ino = list_entry(p, struct autofs_info, rehash);
515 dentry = ino->dentry;
516
517 spin_lock(&dentry->d_lock);
518
519 /* Bad luck, we've already been dentry_iput */
520 if (!dentry->d_inode)
521 goto next;
522
523 qstr = &dentry->d_name;
524
525 if (dentry->d_name.hash != hash)
526 goto next;
527 if (dentry->d_parent != parent)
528 goto next;
529
530 if (qstr->len != len)
531 goto next;
532 if (memcmp(qstr->name, str, len))
533 goto next;
534
535 if (d_unhashed(dentry)) {
536 struct autofs_info *ino = autofs4_dentry_ino(dentry);
537 struct inode *inode = dentry->d_inode;
538
539 list_del_init(&ino->rehash);
540 dget(dentry);
541 /*
542 * Make the rehashed dentry negative so the VFS
543 * behaves as it should.
544 */
545 if (inode) {
546 dentry->d_inode = NULL;
547 list_del_init(&dentry->d_alias);
548 spin_unlock(&dentry->d_lock);
549 spin_unlock(&sbi->rehash_lock);
550 spin_unlock(&dcache_lock);
551 iput(inode);
552 return dentry;
553 }
554 spin_unlock(&dentry->d_lock);
555 spin_unlock(&sbi->rehash_lock);
556 spin_unlock(&dcache_lock);
557 return dentry;
558 }
559 next:
560 spin_unlock(&dentry->d_lock);
561 }
562 spin_unlock(&sbi->rehash_lock);
563 spin_unlock(&dcache_lock);
564
565 return NULL;
566 }
567
568 /* Lookups in the root directory */
569 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
570 {
571 struct autofs_sb_info *sbi;
572 struct dentry *unhashed;
573 int oz_mode;
574
575 DPRINTK("name = %.*s",
576 dentry->d_name.len, dentry->d_name.name);
577
578 /* File name too long to exist */
579 if (dentry->d_name.len > NAME_MAX)
580 return ERR_PTR(-ENAMETOOLONG);
581
582 sbi = autofs4_sbi(dir->i_sb);
583 oz_mode = autofs4_oz_mode(sbi);
584
585 DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
586 current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
587
588 unhashed = autofs4_lookup_unhashed(sbi, dentry->d_parent, &dentry->d_name);
589 if (!unhashed) {
590 /*
591 * Mark the dentry incomplete but don't hash it. We do this
592 * to serialize our inode creation operations (symlink and
593 * mkdir) which prevents deadlock during the callback to
594 * the daemon. Subsequent user space lookups for the same
595 * dentry are placed on the wait queue while the daemon
596 * itself is allowed passage unresticted so the create
597 * operation itself can then hash the dentry. Finally,
598 * we check for the hashed dentry and return the newly
599 * hashed dentry.
600 */
601 dentry->d_op = &autofs4_root_dentry_operations;
602
603 dentry->d_fsdata = NULL;
604 d_instantiate(dentry, NULL);
605 } else {
606 struct autofs_info *ino = autofs4_dentry_ino(unhashed);
607 DPRINTK("rehash %p with %p", dentry, unhashed);
608 /*
609 * If we are racing with expire the request might not
610 * be quite complete but the directory has been removed
611 * so it must have been successful, so just wait for it.
612 * We need to ensure the AUTOFS_INF_EXPIRING flag is clear
613 * before continuing as revalidate may fail when calling
614 * try_to_fill_dentry (returning EAGAIN) if we don't.
615 */
616 while (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
617 DPRINTK("wait for incomplete expire %p name=%.*s",
618 unhashed, unhashed->d_name.len,
619 unhashed->d_name.name);
620 autofs4_wait(sbi, unhashed, NFY_NONE);
621 DPRINTK("request completed");
622 }
623 dentry = unhashed;
624 }
625
626 if (!oz_mode) {
627 spin_lock(&dentry->d_lock);
628 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
629 spin_unlock(&dentry->d_lock);
630 }
631
632 if (dentry->d_op && dentry->d_op->d_revalidate) {
633 mutex_unlock(&dir->i_mutex);
634 (dentry->d_op->d_revalidate)(dentry, nd);
635 mutex_lock(&dir->i_mutex);
636 }
637
638 /*
639 * If we are still pending, check if we had to handle
640 * a signal. If so we can force a restart..
641 */
642 if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
643 /* See if we were interrupted */
644 if (signal_pending(current)) {
645 sigset_t *sigset = &current->pending.signal;
646 if (sigismember (sigset, SIGKILL) ||
647 sigismember (sigset, SIGQUIT) ||
648 sigismember (sigset, SIGINT)) {
649 if (unhashed)
650 dput(unhashed);
651 return ERR_PTR(-ERESTARTNOINTR);
652 }
653 }
654 spin_lock(&dentry->d_lock);
655 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
656 spin_unlock(&dentry->d_lock);
657 }
658
659 /*
660 * If this dentry is unhashed, then we shouldn't honour this
661 * lookup. Returning ENOENT here doesn't do the right thing
662 * for all system calls, but it should be OK for the operations
663 * we permit from an autofs.
664 */
665 if (!oz_mode && d_unhashed(dentry)) {
666 /*
667 * A user space application can (and has done in the past)
668 * remove and re-create this directory during the callback.
669 * This can leave us with an unhashed dentry, but a
670 * successful mount! So we need to perform another
671 * cached lookup in case the dentry now exists.
672 */
673 struct dentry *parent = dentry->d_parent;
674 struct dentry *new = d_lookup(parent, &dentry->d_name);
675 if (new != NULL)
676 dentry = new;
677 else
678 dentry = ERR_PTR(-ENOENT);
679
680 if (unhashed)
681 dput(unhashed);
682
683 return dentry;
684 }
685
686 if (unhashed)
687 return dentry;
688
689 return NULL;
690 }
691
692 static int autofs4_dir_symlink(struct inode *dir,
693 struct dentry *dentry,
694 const char *symname)
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 struct inode *inode;
700 char *cp;
701
702 DPRINTK("%s <- %.*s", symname,
703 dentry->d_name.len, dentry->d_name.name);
704
705 if (!autofs4_oz_mode(sbi))
706 return -EACCES;
707
708 ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
709 if (ino == NULL)
710 return -ENOSPC;
711
712 ino->size = strlen(symname);
713 ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
714
715 if (cp == NULL) {
716 kfree(ino);
717 return -ENOSPC;
718 }
719
720 strcpy(cp, symname);
721
722 inode = autofs4_get_inode(dir->i_sb, ino);
723 d_add(dentry, inode);
724
725 if (dir == dir->i_sb->s_root->d_inode)
726 dentry->d_op = &autofs4_root_dentry_operations;
727 else
728 dentry->d_op = &autofs4_dentry_operations;
729
730 dentry->d_fsdata = ino;
731 ino->dentry = dget(dentry);
732 atomic_inc(&ino->count);
733 p_ino = autofs4_dentry_ino(dentry->d_parent);
734 if (p_ino && dentry->d_parent != dentry)
735 atomic_inc(&p_ino->count);
736 ino->inode = inode;
737
738 dir->i_mtime = CURRENT_TIME;
739
740 return 0;
741 }
742
743 /*
744 * NOTE!
745 *
746 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
747 * that the file no longer exists. However, doing that means that the
748 * VFS layer can turn the dentry into a negative dentry. We don't want
749 * this, because the unlink is probably the result of an expire.
750 * We simply d_drop it and add it to a rehash candidates list in the
751 * super block, which allows the dentry lookup to reuse it retaining
752 * the flags, such as expire in progress, in case we're racing with expire.
753 *
754 * If a process is blocked on the dentry waiting for the expire to finish,
755 * it will invalidate the dentry and try to mount with a new one.
756 *
757 * Also see autofs4_dir_rmdir()..
758 */
759 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
760 {
761 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
762 struct autofs_info *ino = autofs4_dentry_ino(dentry);
763 struct autofs_info *p_ino;
764
765 /* This allows root to remove symlinks */
766 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
767 return -EACCES;
768
769 if (atomic_dec_and_test(&ino->count)) {
770 p_ino = autofs4_dentry_ino(dentry->d_parent);
771 if (p_ino && dentry->d_parent != dentry)
772 atomic_dec(&p_ino->count);
773 }
774 dput(ino->dentry);
775
776 dentry->d_inode->i_size = 0;
777 clear_nlink(dentry->d_inode);
778
779 dir->i_mtime = CURRENT_TIME;
780
781 spin_lock(&dcache_lock);
782 spin_lock(&sbi->rehash_lock);
783 list_add(&ino->rehash, &sbi->rehash_list);
784 spin_unlock(&sbi->rehash_lock);
785 spin_lock(&dentry->d_lock);
786 __d_drop(dentry);
787 spin_unlock(&dentry->d_lock);
788 spin_unlock(&dcache_lock);
789
790 return 0;
791 }
792
793 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
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
799 DPRINTK("dentry %p, removing %.*s",
800 dentry, dentry->d_name.len, dentry->d_name.name);
801
802 if (!autofs4_oz_mode(sbi))
803 return -EACCES;
804
805 spin_lock(&dcache_lock);
806 if (!list_empty(&dentry->d_subdirs)) {
807 spin_unlock(&dcache_lock);
808 return -ENOTEMPTY;
809 }
810 spin_lock(&sbi->rehash_lock);
811 list_add(&ino->rehash, &sbi->rehash_list);
812 spin_unlock(&sbi->rehash_lock);
813 spin_lock(&dentry->d_lock);
814 __d_drop(dentry);
815 spin_unlock(&dentry->d_lock);
816 spin_unlock(&dcache_lock);
817
818 if (atomic_dec_and_test(&ino->count)) {
819 p_ino = autofs4_dentry_ino(dentry->d_parent);
820 if (p_ino && dentry->d_parent != dentry)
821 atomic_dec(&p_ino->count);
822 }
823 dput(ino->dentry);
824 dentry->d_inode->i_size = 0;
825 clear_nlink(dentry->d_inode);
826
827 if (dir->i_nlink)
828 drop_nlink(dir);
829
830 return 0;
831 }
832
833 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
834 {
835 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
836 struct autofs_info *ino = autofs4_dentry_ino(dentry);
837 struct autofs_info *p_ino;
838 struct inode *inode;
839
840 if (!autofs4_oz_mode(sbi))
841 return -EACCES;
842
843 DPRINTK("dentry %p, creating %.*s",
844 dentry, dentry->d_name.len, dentry->d_name.name);
845
846 ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
847 if (ino == NULL)
848 return -ENOSPC;
849
850 inode = autofs4_get_inode(dir->i_sb, ino);
851 d_add(dentry, inode);
852
853 if (dir == dir->i_sb->s_root->d_inode)
854 dentry->d_op = &autofs4_root_dentry_operations;
855 else
856 dentry->d_op = &autofs4_dentry_operations;
857
858 dentry->d_fsdata = ino;
859 ino->dentry = dget(dentry);
860 atomic_inc(&ino->count);
861 p_ino = autofs4_dentry_ino(dentry->d_parent);
862 if (p_ino && dentry->d_parent != dentry)
863 atomic_inc(&p_ino->count);
864 ino->inode = inode;
865 inc_nlink(dir);
866 dir->i_mtime = CURRENT_TIME;
867
868 return 0;
869 }
870
871 /* Get/set timeout ioctl() operation */
872 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
873 unsigned long __user *p)
874 {
875 int rv;
876 unsigned long ntimeout;
877
878 if ((rv = get_user(ntimeout, p)) ||
879 (rv = put_user(sbi->exp_timeout/HZ, p)))
880 return rv;
881
882 if (ntimeout > ULONG_MAX/HZ)
883 sbi->exp_timeout = 0;
884 else
885 sbi->exp_timeout = ntimeout * HZ;
886
887 return 0;
888 }
889
890 /* Return protocol version */
891 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
892 {
893 return put_user(sbi->version, p);
894 }
895
896 /* Return protocol sub version */
897 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
898 {
899 return put_user(sbi->sub_version, p);
900 }
901
902 /*
903 * Tells the daemon whether we need to reghost or not. Also, clears
904 * the reghost_needed flag.
905 */
906 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
907 {
908 int status;
909
910 DPRINTK("returning %d", sbi->needs_reghost);
911
912 status = put_user(sbi->needs_reghost, p);
913 if (status)
914 return status;
915
916 sbi->needs_reghost = 0;
917 return 0;
918 }
919
920 /*
921 * Enable / Disable reghosting ioctl() operation
922 */
923 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
924 {
925 int status;
926 int val;
927
928 status = get_user(val, p);
929
930 DPRINTK("reghost = %d", val);
931
932 if (status)
933 return status;
934
935 /* turn on/off reghosting, with the val */
936 sbi->reghost_enabled = val;
937 return 0;
938 }
939
940 /*
941 * Tells the daemon whether it can umount the autofs mount.
942 */
943 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
944 {
945 int status = 0;
946
947 if (may_umount(mnt))
948 status = 1;
949
950 DPRINTK("returning %d", status);
951
952 status = put_user(status, p);
953
954 return status;
955 }
956
957 /* Identify autofs4_dentries - this is so we can tell if there's
958 an extra dentry refcount or not. We only hold a refcount on the
959 dentry if its non-negative (ie, d_inode != NULL)
960 */
961 int is_autofs4_dentry(struct dentry *dentry)
962 {
963 return dentry && dentry->d_inode &&
964 (dentry->d_op == &autofs4_root_dentry_operations ||
965 dentry->d_op == &autofs4_dentry_operations) &&
966 dentry->d_fsdata != NULL;
967 }
968
969 /*
970 * ioctl()'s on the root directory is the chief method for the daemon to
971 * generate kernel reactions
972 */
973 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
974 unsigned int cmd, unsigned long arg)
975 {
976 struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
977 void __user *p = (void __user *)arg;
978
979 DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
980 cmd,arg,sbi,task_pgrp_nr(current));
981
982 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
983 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
984 return -ENOTTY;
985
986 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
987 return -EPERM;
988
989 switch(cmd) {
990 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
991 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
992 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
993 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
994 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
995 autofs4_catatonic_mode(sbi);
996 return 0;
997 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
998 return autofs4_get_protover(sbi, p);
999 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
1000 return autofs4_get_protosubver(sbi, p);
1001 case AUTOFS_IOC_SETTIMEOUT:
1002 return autofs4_get_set_timeout(sbi, p);
1003
1004 case AUTOFS_IOC_TOGGLEREGHOST:
1005 return autofs4_toggle_reghost(sbi, p);
1006 case AUTOFS_IOC_ASKREGHOST:
1007 return autofs4_ask_reghost(sbi, p);
1008
1009 case AUTOFS_IOC_ASKUMOUNT:
1010 return autofs4_ask_umount(filp->f_path.mnt, p);
1011
1012 /* return a single thing to expire */
1013 case AUTOFS_IOC_EXPIRE:
1014 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
1015 /* same as above, but can send multiple expires through pipe */
1016 case AUTOFS_IOC_EXPIRE_MULTI:
1017 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
1018
1019 default:
1020 return -ENOSYS;
1021 }
1022 }
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