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Revert "ovl: fix relatime for directories"
[linux/fpc-iii.git] / fs / overlayfs / super.c
bloba7e2287e4b8f6c7ca3180015521dac544dde13d4
1 /*
2 *
3 * Copyright (C) 2011 Novell Inc.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
8 */
9
10 #include <uapi/linux/magic.h>
11 #include <linux/fs.h>
12 #include <linux/namei.h>
13 #include <linux/xattr.h>
14 #include <linux/mount.h>
15 #include <linux/parser.h>
16 #include <linux/module.h>
17 #include <linux/statfs.h>
18 #include <linux/seq_file.h>
19 #include <linux/posix_acl_xattr.h>
20 #include <linux/exportfs.h>
21 #include "overlayfs.h"
22
23 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
24 MODULE_DESCRIPTION("Overlay filesystem");
25 MODULE_LICENSE("GPL");
26
27
28 struct ovl_dir_cache;
29
30 #define OVL_MAX_STACK 500
31
32 static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
33 module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
34 MODULE_PARM_DESC(ovl_redirect_dir_def,
35 "Default to on or off for the redirect_dir feature");
36
37 static bool ovl_redirect_always_follow =
38 IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW);
39 module_param_named(redirect_always_follow, ovl_redirect_always_follow,
40 bool, 0644);
41 MODULE_PARM_DESC(ovl_redirect_always_follow,
42 "Follow redirects even if redirect_dir feature is turned off");
43
44 static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
45 module_param_named(index, ovl_index_def, bool, 0644);
46 MODULE_PARM_DESC(ovl_index_def,
47 "Default to on or off for the inodes index feature");
48
49 static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT);
50 module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644);
51 MODULE_PARM_DESC(ovl_nfs_export_def,
52 "Default to on or off for the NFS export feature");
53
54 static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
55 module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
56 MODULE_PARM_DESC(ovl_xino_auto_def,
57 "Auto enable xino feature");
58
59 static void ovl_entry_stack_free(struct ovl_entry *oe)
60 {
61 unsigned int i;
62
63 for (i = 0; i < oe->numlower; i++)
64 dput(oe->lowerstack[i].dentry);
65 }
66
67 static void ovl_dentry_release(struct dentry *dentry)
68 {
69 struct ovl_entry *oe = dentry->d_fsdata;
70
71 if (oe) {
72 ovl_entry_stack_free(oe);
73 kfree_rcu(oe, rcu);
74 }
75 }
76
77 static int ovl_check_append_only(struct inode *inode, int flag)
78 {
79 /*
80 * This test was moot in vfs may_open() because overlay inode does
81 * not have the S_APPEND flag, so re-check on real upper inode
82 */
83 if (IS_APPEND(inode)) {
84 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
85 return -EPERM;
86 if (flag & O_TRUNC)
87 return -EPERM;
88 }
89
90 return 0;
91 }
92
93 static struct dentry *ovl_d_real(struct dentry *dentry,
94 const struct inode *inode,
95 unsigned int open_flags, unsigned int flags)
96 {
97 struct dentry *real;
98 int err;
99
100 /* It's an overlay file */
101 if (inode && d_inode(dentry) == inode)
102 return dentry;
103
104 if (!d_is_reg(dentry)) {
105 if (!inode || inode == d_inode(dentry))
106 return dentry;
107 goto bug;
108 }
109
110 if (open_flags) {
111 err = ovl_open_maybe_copy_up(dentry, open_flags);
112 if (err)
113 return ERR_PTR(err);
114 }
115
116 real = ovl_dentry_upper(dentry);
117 if (real && (!inode || inode == d_inode(real))) {
118 if (!inode) {
119 err = ovl_check_append_only(d_inode(real), open_flags);
120 if (err)
121 return ERR_PTR(err);
122 }
123 return real;
124 }
125
126 real = ovl_dentry_lower(dentry);
127 if (!real)
128 goto bug;
129
130 /* Handle recursion */
131 real = d_real(real, inode, open_flags, 0);
132
133 if (!inode || inode == d_inode(real))
134 return real;
135 bug:
136 WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry,
137 inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
138 return dentry;
139 }
140
141 static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
142 {
143 struct ovl_entry *oe = dentry->d_fsdata;
144 unsigned int i;
145 int ret = 1;
146
147 for (i = 0; i < oe->numlower; i++) {
148 struct dentry *d = oe->lowerstack[i].dentry;
149
150 if (d->d_flags & DCACHE_OP_REVALIDATE) {
151 ret = d->d_op->d_revalidate(d, flags);
152 if (ret < 0)
153 return ret;
154 if (!ret) {
155 if (!(flags & LOOKUP_RCU))
156 d_invalidate(d);
157 return -ESTALE;
158 }
159 }
160 }
161 return 1;
162 }
163
164 static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
165 {
166 struct ovl_entry *oe = dentry->d_fsdata;
167 unsigned int i;
168 int ret = 1;
169
170 for (i = 0; i < oe->numlower; i++) {
171 struct dentry *d = oe->lowerstack[i].dentry;
172
173 if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
174 ret = d->d_op->d_weak_revalidate(d, flags);
175 if (ret <= 0)
176 break;
177 }
178 }
179 return ret;
180 }
181
182 static const struct dentry_operations ovl_dentry_operations = {
183 .d_release = ovl_dentry_release,
184 .d_real = ovl_d_real,
185 };
186
187 static const struct dentry_operations ovl_reval_dentry_operations = {
188 .d_release = ovl_dentry_release,
189 .d_real = ovl_d_real,
190 .d_revalidate = ovl_dentry_revalidate,
191 .d_weak_revalidate = ovl_dentry_weak_revalidate,
192 };
193
194 static struct kmem_cache *ovl_inode_cachep;
195
196 static struct inode *ovl_alloc_inode(struct super_block *sb)
197 {
198 struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL);
199
200 if (!oi)
201 return NULL;
202
203 oi->cache = NULL;
204 oi->redirect = NULL;
205 oi->version = 0;
206 oi->flags = 0;
207 oi->__upperdentry = NULL;
208 oi->lower = NULL;
209 mutex_init(&oi->lock);
210
211 return &oi->vfs_inode;
212 }
213
214 static void ovl_i_callback(struct rcu_head *head)
215 {
216 struct inode *inode = container_of(head, struct inode, i_rcu);
217
218 kmem_cache_free(ovl_inode_cachep, OVL_I(inode));
219 }
220
221 static void ovl_destroy_inode(struct inode *inode)
222 {
223 struct ovl_inode *oi = OVL_I(inode);
224
225 dput(oi->__upperdentry);
226 iput(oi->lower);
227 kfree(oi->redirect);
228 ovl_dir_cache_free(inode);
229 mutex_destroy(&oi->lock);
230
231 call_rcu(&inode->i_rcu, ovl_i_callback);
232 }
233
234 static void ovl_free_fs(struct ovl_fs *ofs)
235 {
236 unsigned i;
237
238 dput(ofs->indexdir);
239 dput(ofs->workdir);
240 if (ofs->workdir_locked)
241 ovl_inuse_unlock(ofs->workbasedir);
242 dput(ofs->workbasedir);
243 if (ofs->upperdir_locked)
244 ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
245 mntput(ofs->upper_mnt);
246 for (i = 0; i < ofs->numlower; i++)
247 mntput(ofs->lower_layers[i].mnt);
248 for (i = 0; i < ofs->numlowerfs; i++)
249 free_anon_bdev(ofs->lower_fs[i].pseudo_dev);
250 kfree(ofs->lower_layers);
251 kfree(ofs->lower_fs);
252
253 kfree(ofs->config.lowerdir);
254 kfree(ofs->config.upperdir);
255 kfree(ofs->config.workdir);
256 kfree(ofs->config.redirect_mode);
257 if (ofs->creator_cred)
258 put_cred(ofs->creator_cred);
259 kfree(ofs);
260 }
261
262 static void ovl_put_super(struct super_block *sb)
263 {
264 struct ovl_fs *ofs = sb->s_fs_info;
265
266 ovl_free_fs(ofs);
267 }
268
269 /* Sync real dirty inodes in upper filesystem (if it exists) */
270 static int ovl_sync_fs(struct super_block *sb, int wait)
271 {
272 struct ovl_fs *ofs = sb->s_fs_info;
273 struct super_block *upper_sb;
274 int ret;
275
276 if (!ofs->upper_mnt)
277 return 0;
278
279 /*
280 * If this is a sync(2) call or an emergency sync, all the super blocks
281 * will be iterated, including upper_sb, so no need to do anything.
282 *
283 * If this is a syncfs(2) call, then we do need to call
284 * sync_filesystem() on upper_sb, but enough if we do it when being
285 * called with wait == 1.
286 */
287 if (!wait)
288 return 0;
289
290 upper_sb = ofs->upper_mnt->mnt_sb;
291
292 down_read(&upper_sb->s_umount);
293 ret = sync_filesystem(upper_sb);
294 up_read(&upper_sb->s_umount);
295
296 return ret;
297 }
298
299 /**
300 * ovl_statfs
301 * @sb: The overlayfs super block
302 * @buf: The struct kstatfs to fill in with stats
303 *
304 * Get the filesystem statistics. As writes always target the upper layer
305 * filesystem pass the statfs to the upper filesystem (if it exists)
306 */
307 static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
308 {
309 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
310 struct dentry *root_dentry = dentry->d_sb->s_root;
311 struct path path;
312 int err;
313
314 ovl_path_real(root_dentry, &path);
315
316 err = vfs_statfs(&path, buf);
317 if (!err) {
318 buf->f_namelen = ofs->namelen;
319 buf->f_type = OVERLAYFS_SUPER_MAGIC;
320 }
321
322 return err;
323 }
324
325 /* Will this overlay be forced to mount/remount ro? */
326 static bool ovl_force_readonly(struct ovl_fs *ofs)
327 {
328 return (!ofs->upper_mnt || !ofs->workdir);
329 }
330
331 static const char *ovl_redirect_mode_def(void)
332 {
333 return ovl_redirect_dir_def ? "on" : "off";
334 }
335
336 enum {
337 OVL_XINO_OFF,
338 OVL_XINO_AUTO,
339 OVL_XINO_ON,
340 };
341
342 static const char * const ovl_xino_str[] = {
343 "off",
344 "auto",
345 "on",
346 };
347
348 static inline int ovl_xino_def(void)
349 {
350 return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
351 }
352
353 /**
354 * ovl_show_options
355 *
356 * Prints the mount options for a given superblock.
357 * Returns zero; does not fail.
358 */
359 static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
360 {
361 struct super_block *sb = dentry->d_sb;
362 struct ovl_fs *ofs = sb->s_fs_info;
363
364 seq_show_option(m, "lowerdir", ofs->config.lowerdir);
365 if (ofs->config.upperdir) {
366 seq_show_option(m, "upperdir", ofs->config.upperdir);
367 seq_show_option(m, "workdir", ofs->config.workdir);
368 }
369 if (ofs->config.default_permissions)
370 seq_puts(m, ",default_permissions");
371 if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0)
372 seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode);
373 if (ofs->config.index != ovl_index_def)
374 seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
375 if (ofs->config.nfs_export != ovl_nfs_export_def)
376 seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
377 "on" : "off");
378 if (ofs->config.xino != ovl_xino_def())
379 seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
380 return 0;
381 }
382
383 static int ovl_remount(struct super_block *sb, int *flags, char *data)
384 {
385 struct ovl_fs *ofs = sb->s_fs_info;
386
387 if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
388 return -EROFS;
389
390 return 0;
391 }
392
393 static const struct super_operations ovl_super_operations = {
394 .alloc_inode = ovl_alloc_inode,
395 .destroy_inode = ovl_destroy_inode,
396 .drop_inode = generic_delete_inode,
397 .put_super = ovl_put_super,
398 .sync_fs = ovl_sync_fs,
399 .statfs = ovl_statfs,
400 .show_options = ovl_show_options,
401 .remount_fs = ovl_remount,
402 };
403
404 enum {
405 OPT_LOWERDIR,
406 OPT_UPPERDIR,
407 OPT_WORKDIR,
408 OPT_DEFAULT_PERMISSIONS,
409 OPT_REDIRECT_DIR,
410 OPT_INDEX_ON,
411 OPT_INDEX_OFF,
412 OPT_NFS_EXPORT_ON,
413 OPT_NFS_EXPORT_OFF,
414 OPT_XINO_ON,
415 OPT_XINO_OFF,
416 OPT_XINO_AUTO,
417 OPT_ERR,
418 };
419
420 static const match_table_t ovl_tokens = {
421 {OPT_LOWERDIR, "lowerdir=%s"},
422 {OPT_UPPERDIR, "upperdir=%s"},
423 {OPT_WORKDIR, "workdir=%s"},
424 {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
425 {OPT_REDIRECT_DIR, "redirect_dir=%s"},
426 {OPT_INDEX_ON, "index=on"},
427 {OPT_INDEX_OFF, "index=off"},
428 {OPT_NFS_EXPORT_ON, "nfs_export=on"},
429 {OPT_NFS_EXPORT_OFF, "nfs_export=off"},
430 {OPT_XINO_ON, "xino=on"},
431 {OPT_XINO_OFF, "xino=off"},
432 {OPT_XINO_AUTO, "xino=auto"},
433 {OPT_ERR, NULL}
434 };
435
436 static char *ovl_next_opt(char **s)
437 {
438 char *sbegin = *s;
439 char *p;
440
441 if (sbegin == NULL)
442 return NULL;
443
444 for (p = sbegin; *p; p++) {
445 if (*p == '\\') {
446 p++;
447 if (!*p)
448 break;
449 } else if (*p == ',') {
450 *p = '\0';
451 *s = p + 1;
452 return sbegin;
453 }
454 }
455 *s = NULL;
456 return sbegin;
457 }
458
459 static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
460 {
461 if (strcmp(mode, "on") == 0) {
462 config->redirect_dir = true;
463 /*
464 * Does not make sense to have redirect creation without
465 * redirect following.
466 */
467 config->redirect_follow = true;
468 } else if (strcmp(mode, "follow") == 0) {
469 config->redirect_follow = true;
470 } else if (strcmp(mode, "off") == 0) {
471 if (ovl_redirect_always_follow)
472 config->redirect_follow = true;
473 } else if (strcmp(mode, "nofollow") != 0) {
474 pr_err("overlayfs: bad mount option \"redirect_dir=%s\"\n",
475 mode);
476 return -EINVAL;
477 }
478
479 return 0;
480 }
481
482 static int ovl_parse_opt(char *opt, struct ovl_config *config)
483 {
484 char *p;
485
486 config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
487 if (!config->redirect_mode)
488 return -ENOMEM;
489
490 while ((p = ovl_next_opt(&opt)) != NULL) {
491 int token;
492 substring_t args[MAX_OPT_ARGS];
493
494 if (!*p)
495 continue;
496
497 token = match_token(p, ovl_tokens, args);
498 switch (token) {
499 case OPT_UPPERDIR:
500 kfree(config->upperdir);
501 config->upperdir = match_strdup(&args[0]);
502 if (!config->upperdir)
503 return -ENOMEM;
504 break;
505
506 case OPT_LOWERDIR:
507 kfree(config->lowerdir);
508 config->lowerdir = match_strdup(&args[0]);
509 if (!config->lowerdir)
510 return -ENOMEM;
511 break;
512
513 case OPT_WORKDIR:
514 kfree(config->workdir);
515 config->workdir = match_strdup(&args[0]);
516 if (!config->workdir)
517 return -ENOMEM;
518 break;
519
520 case OPT_DEFAULT_PERMISSIONS:
521 config->default_permissions = true;
522 break;
523
524 case OPT_REDIRECT_DIR:
525 kfree(config->redirect_mode);
526 config->redirect_mode = match_strdup(&args[0]);
527 if (!config->redirect_mode)
528 return -ENOMEM;
529 break;
530
531 case OPT_INDEX_ON:
532 config->index = true;
533 break;
534
535 case OPT_INDEX_OFF:
536 config->index = false;
537 break;
538
539 case OPT_NFS_EXPORT_ON:
540 config->nfs_export = true;
541 break;
542
543 case OPT_NFS_EXPORT_OFF:
544 config->nfs_export = false;
545 break;
546
547 case OPT_XINO_ON:
548 config->xino = OVL_XINO_ON;
549 break;
550
551 case OPT_XINO_OFF:
552 config->xino = OVL_XINO_OFF;
553 break;
554
555 case OPT_XINO_AUTO:
556 config->xino = OVL_XINO_AUTO;
557 break;
558
559 default:
560 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
561 return -EINVAL;
562 }
563 }
564
565 /* Workdir is useless in non-upper mount */
566 if (!config->upperdir && config->workdir) {
567 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
568 config->workdir);
569 kfree(config->workdir);
570 config->workdir = NULL;
571 }
572
573 return ovl_parse_redirect_mode(config, config->redirect_mode);
574 }
575
576 #define OVL_WORKDIR_NAME "work"
577 #define OVL_INDEXDIR_NAME "index"
578
579 static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
580 const char *name, bool persist)
581 {
582 struct inode *dir = ofs->workbasedir->d_inode;
583 struct vfsmount *mnt = ofs->upper_mnt;
584 struct dentry *work;
585 int err;
586 bool retried = false;
587 bool locked = false;
588
589 inode_lock_nested(dir, I_MUTEX_PARENT);
590 locked = true;
591
592 retry:
593 work = lookup_one_len(name, ofs->workbasedir, strlen(name));
594
595 if (!IS_ERR(work)) {
596 struct iattr attr = {
597 .ia_valid = ATTR_MODE,
598 .ia_mode = S_IFDIR | 0,
599 };
600
601 if (work->d_inode) {
602 err = -EEXIST;
603 if (retried)
604 goto out_dput;
605
606 if (persist)
607 goto out_unlock;
608
609 retried = true;
610 ovl_workdir_cleanup(dir, mnt, work, 0);
611 dput(work);
612 goto retry;
613 }
614
615 work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode));
616 err = PTR_ERR(work);
617 if (IS_ERR(work))
618 goto out_err;
619
620 /*
621 * Try to remove POSIX ACL xattrs from workdir. We are good if:
622 *
623 * a) success (there was a POSIX ACL xattr and was removed)
624 * b) -ENODATA (there was no POSIX ACL xattr)
625 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
626 *
627 * There are various other error values that could effectively
628 * mean that the xattr doesn't exist (e.g. -ERANGE is returned
629 * if the xattr name is too long), but the set of filesystems
630 * allowed as upper are limited to "normal" ones, where checking
631 * for the above two errors is sufficient.
632 */
633 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
634 if (err && err != -ENODATA && err != -EOPNOTSUPP)
635 goto out_dput;
636
637 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
638 if (err && err != -ENODATA && err != -EOPNOTSUPP)
639 goto out_dput;
640
641 /* Clear any inherited mode bits */
642 inode_lock(work->d_inode);
643 err = notify_change(work, &attr, NULL);
644 inode_unlock(work->d_inode);
645 if (err)
646 goto out_dput;
647 } else {
648 err = PTR_ERR(work);
649 goto out_err;
650 }
651 out_unlock:
652 if (locked)
653 inode_unlock(dir);
654
655 return work;
656
657 out_dput:
658 dput(work);
659 out_err:
660 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
661 ofs->config.workdir, name, -err);
662 work = NULL;
663 goto out_unlock;
664 }
665
666 static void ovl_unescape(char *s)
667 {
668 char *d = s;
669
670 for (;; s++, d++) {
671 if (*s == '\\')
672 s++;
673 *d = *s;
674 if (!*s)
675 break;
676 }
677 }
678
679 static int ovl_mount_dir_noesc(const char *name, struct path *path)
680 {
681 int err = -EINVAL;
682
683 if (!*name) {
684 pr_err("overlayfs: empty lowerdir\n");
685 goto out;
686 }
687 err = kern_path(name, LOOKUP_FOLLOW, path);
688 if (err) {
689 pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
690 goto out;
691 }
692 err = -EINVAL;
693 if (ovl_dentry_weird(path->dentry)) {
694 pr_err("overlayfs: filesystem on '%s' not supported\n", name);
695 goto out_put;
696 }
697 if (!d_is_dir(path->dentry)) {
698 pr_err("overlayfs: '%s' not a directory\n", name);
699 goto out_put;
700 }
701 return 0;
702
703 out_put:
704 path_put_init(path);
705 out:
706 return err;
707 }
708
709 static int ovl_mount_dir(const char *name, struct path *path)
710 {
711 int err = -ENOMEM;
712 char *tmp = kstrdup(name, GFP_KERNEL);
713
714 if (tmp) {
715 ovl_unescape(tmp);
716 err = ovl_mount_dir_noesc(tmp, path);
717
718 if (!err)
719 if (ovl_dentry_remote(path->dentry)) {
720 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
721 tmp);
722 path_put_init(path);
723 err = -EINVAL;
724 }
725 kfree(tmp);
726 }
727 return err;
728 }
729
730 static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
731 const char *name)
732 {
733 struct kstatfs statfs;
734 int err = vfs_statfs(path, &statfs);
735
736 if (err)
737 pr_err("overlayfs: statfs failed on '%s'\n", name);
738 else
739 ofs->namelen = max(ofs->namelen, statfs.f_namelen);
740
741 return err;
742 }
743
744 static int ovl_lower_dir(const char *name, struct path *path,
745 struct ovl_fs *ofs, int *stack_depth, bool *remote)
746 {
747 int fh_type;
748 int err;
749
750 err = ovl_mount_dir_noesc(name, path);
751 if (err)
752 goto out;
753
754 err = ovl_check_namelen(path, ofs, name);
755 if (err)
756 goto out_put;
757
758 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
759
760 if (ovl_dentry_remote(path->dentry))
761 *remote = true;
762
763 /*
764 * The inodes index feature and NFS export need to encode and decode
765 * file handles, so they require that all layers support them.
766 */
767 fh_type = ovl_can_decode_fh(path->dentry->d_sb);
768 if ((ofs->config.nfs_export ||
769 (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
770 ofs->config.index = false;
771 ofs->config.nfs_export = false;
772 pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
773 name);
774 }
775
776 /* Check if lower fs has 32bit inode numbers */
777 if (fh_type != FILEID_INO32_GEN)
778 ofs->xino_bits = 0;
779
780 return 0;
781
782 out_put:
783 path_put_init(path);
784 out:
785 return err;
786 }
787
788 /* Workdir should not be subdir of upperdir and vice versa */
789 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
790 {
791 bool ok = false;
792
793 if (workdir != upperdir) {
794 ok = (lock_rename(workdir, upperdir) == NULL);
795 unlock_rename(workdir, upperdir);
796 }
797 return ok;
798 }
799
800 static unsigned int ovl_split_lowerdirs(char *str)
801 {
802 unsigned int ctr = 1;
803 char *s, *d;
804
805 for (s = d = str;; s++, d++) {
806 if (*s == '\\') {
807 s++;
808 } else if (*s == ':') {
809 *d = '\0';
810 ctr++;
811 continue;
812 }
813 *d = *s;
814 if (!*s)
815 break;
816 }
817 return ctr;
818 }
819
820 static int __maybe_unused
821 ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
822 struct dentry *dentry, struct inode *inode,
823 const char *name, void *buffer, size_t size)
824 {
825 return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
826 }
827
828 static int __maybe_unused
829 ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
830 struct dentry *dentry, struct inode *inode,
831 const char *name, const void *value,
832 size_t size, int flags)
833 {
834 struct dentry *workdir = ovl_workdir(dentry);
835 struct inode *realinode = ovl_inode_real(inode);
836 struct posix_acl *acl = NULL;
837 int err;
838
839 /* Check that everything is OK before copy-up */
840 if (value) {
841 acl = posix_acl_from_xattr(&init_user_ns, value, size);
842 if (IS_ERR(acl))
843 return PTR_ERR(acl);
844 }
845 err = -EOPNOTSUPP;
846 if (!IS_POSIXACL(d_inode(workdir)))
847 goto out_acl_release;
848 if (!realinode->i_op->set_acl)
849 goto out_acl_release;
850 if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
851 err = acl ? -EACCES : 0;
852 goto out_acl_release;
853 }
854 err = -EPERM;
855 if (!inode_owner_or_capable(inode))
856 goto out_acl_release;
857
858 posix_acl_release(acl);
859
860 /*
861 * Check if sgid bit needs to be cleared (actual setacl operation will
862 * be done with mounter's capabilities and so that won't do it for us).
863 */
864 if (unlikely(inode->i_mode & S_ISGID) &&
865 handler->flags == ACL_TYPE_ACCESS &&
866 !in_group_p(inode->i_gid) &&
867 !capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
868 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
869
870 err = ovl_setattr(dentry, &iattr);
871 if (err)
872 return err;
873 }
874
875 err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
876 if (!err)
877 ovl_copyattr(ovl_inode_real(inode), inode);
878
879 return err;
880
881 out_acl_release:
882 posix_acl_release(acl);
883 return err;
884 }
885
886 static int ovl_own_xattr_get(const struct xattr_handler *handler,
887 struct dentry *dentry, struct inode *inode,
888 const char *name, void *buffer, size_t size)
889 {
890 return -EOPNOTSUPP;
891 }
892
893 static int ovl_own_xattr_set(const struct xattr_handler *handler,
894 struct dentry *dentry, struct inode *inode,
895 const char *name, const void *value,
896 size_t size, int flags)
897 {
898 return -EOPNOTSUPP;
899 }
900
901 static int ovl_other_xattr_get(const struct xattr_handler *handler,
902 struct dentry *dentry, struct inode *inode,
903 const char *name, void *buffer, size_t size)
904 {
905 return ovl_xattr_get(dentry, inode, name, buffer, size);
906 }
907
908 static int ovl_other_xattr_set(const struct xattr_handler *handler,
909 struct dentry *dentry, struct inode *inode,
910 const char *name, const void *value,
911 size_t size, int flags)
912 {
913 return ovl_xattr_set(dentry, inode, name, value, size, flags);
914 }
915
916 static const struct xattr_handler __maybe_unused
917 ovl_posix_acl_access_xattr_handler = {
918 .name = XATTR_NAME_POSIX_ACL_ACCESS,
919 .flags = ACL_TYPE_ACCESS,
920 .get = ovl_posix_acl_xattr_get,
921 .set = ovl_posix_acl_xattr_set,
922 };
923
924 static const struct xattr_handler __maybe_unused
925 ovl_posix_acl_default_xattr_handler = {
926 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
927 .flags = ACL_TYPE_DEFAULT,
928 .get = ovl_posix_acl_xattr_get,
929 .set = ovl_posix_acl_xattr_set,
930 };
931
932 static const struct xattr_handler ovl_own_xattr_handler = {
933 .prefix = OVL_XATTR_PREFIX,
934 .get = ovl_own_xattr_get,
935 .set = ovl_own_xattr_set,
936 };
937
938 static const struct xattr_handler ovl_other_xattr_handler = {
939 .prefix = "", /* catch all */
940 .get = ovl_other_xattr_get,
941 .set = ovl_other_xattr_set,
942 };
943
944 static const struct xattr_handler *ovl_xattr_handlers[] = {
945 #ifdef CONFIG_FS_POSIX_ACL
946 &ovl_posix_acl_access_xattr_handler,
947 &ovl_posix_acl_default_xattr_handler,
948 #endif
949 &ovl_own_xattr_handler,
950 &ovl_other_xattr_handler,
951 NULL
952 };
953
954 static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath)
955 {
956 struct vfsmount *upper_mnt;
957 int err;
958
959 err = ovl_mount_dir(ofs->config.upperdir, upperpath);
960 if (err)
961 goto out;
962
963 /* Upper fs should not be r/o */
964 if (sb_rdonly(upperpath->mnt->mnt_sb)) {
965 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
966 err = -EINVAL;
967 goto out;
968 }
969
970 err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir);
971 if (err)
972 goto out;
973
974 err = -EBUSY;
975 if (ovl_inuse_trylock(upperpath->dentry)) {
976 ofs->upperdir_locked = true;
977 } else if (ofs->config.index) {
978 pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");
979 goto out;
980 } else {
981 pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
982 }
983
984 upper_mnt = clone_private_mount(upperpath);
985 err = PTR_ERR(upper_mnt);
986 if (IS_ERR(upper_mnt)) {
987 pr_err("overlayfs: failed to clone upperpath\n");
988 goto out;
989 }
990
991 /* Don't inherit atime flags */
992 upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
993 ofs->upper_mnt = upper_mnt;
994 err = 0;
995 out:
996 return err;
997 }
998
999 static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
1000 {
1001 struct vfsmount *mnt = ofs->upper_mnt;
1002 struct dentry *temp;
1003 int fh_type;
1004 int err;
1005
1006 err = mnt_want_write(mnt);
1007 if (err)
1008 return err;
1009
1010 ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
1011 if (!ofs->workdir)
1012 goto out;
1013
1014 /*
1015 * Upper should support d_type, else whiteouts are visible. Given
1016 * workdir and upper are on same fs, we can do iterate_dir() on
1017 * workdir. This check requires successful creation of workdir in
1018 * previous step.
1019 */
1020 err = ovl_check_d_type_supported(workpath);
1021 if (err < 0)
1022 goto out;
1023
1024 /*
1025 * We allowed this configuration and don't want to break users over
1026 * kernel upgrade. So warn instead of erroring out.
1027 */
1028 if (!err)
1029 pr_warn("overlayfs: upper fs needs to support d_type.\n");
1030
1031 /* Check if upper/work fs supports O_TMPFILE */
1032 temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
1033 ofs->tmpfile = !IS_ERR(temp);
1034 if (ofs->tmpfile)
1035 dput(temp);
1036 else
1037 pr_warn("overlayfs: upper fs does not support tmpfile.\n");
1038
1039 /*
1040 * Check if upper/work fs supports trusted.overlay.* xattr
1041 */
1042 err = ovl_do_setxattr(ofs->workdir, OVL_XATTR_OPAQUE, "0", 1, 0);
1043 if (err) {
1044 ofs->noxattr = true;
1045 ofs->config.index = false;
1046 pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off.\n");
1047 err = 0;
1048 } else {
1049 vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
1050 }
1051
1052 /* Check if upper/work fs supports file handles */
1053 fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
1054 if (ofs->config.index && !fh_type) {
1055 ofs->config.index = false;
1056 pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
1057 }
1058
1059 /* Check if upper fs has 32bit inode numbers */
1060 if (fh_type != FILEID_INO32_GEN)
1061 ofs->xino_bits = 0;
1062
1063 /* NFS export of r/w mount depends on index */
1064 if (ofs->config.nfs_export && !ofs->config.index) {
1065 pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
1066 ofs->config.nfs_export = false;
1067 }
1068
1069 out:
1070 mnt_drop_write(mnt);
1071 return err;
1072 }
1073
1074 static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
1075 {
1076 int err;
1077 struct path workpath = { };
1078
1079 err = ovl_mount_dir(ofs->config.workdir, &workpath);
1080 if (err)
1081 goto out;
1082
1083 err = -EINVAL;
1084 if (upperpath->mnt != workpath.mnt) {
1085 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
1086 goto out;
1087 }
1088 if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) {
1089 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
1090 goto out;
1091 }
1092
1093 err = -EBUSY;
1094 if (ovl_inuse_trylock(workpath.dentry)) {
1095 ofs->workdir_locked = true;
1096 } else if (ofs->config.index) {
1097 pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n");
1098 goto out;
1099 } else {
1100 pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
1101 }
1102
1103 ofs->workbasedir = dget(workpath.dentry);
1104 err = ovl_make_workdir(ofs, &workpath);
1105 if (err)
1106 goto out;
1107
1108 err = 0;
1109 out:
1110 path_put(&workpath);
1111
1112 return err;
1113 }
1114
1115 static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
1116 struct path *upperpath)
1117 {
1118 struct vfsmount *mnt = ofs->upper_mnt;
1119 int err;
1120
1121 err = mnt_want_write(mnt);
1122 if (err)
1123 return err;
1124
1125 /* Verify lower root is upper root origin */
1126 err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
1127 true);
1128 if (err) {
1129 pr_err("overlayfs: failed to verify upper root origin\n");
1130 goto out;
1131 }
1132
1133 ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
1134 if (ofs->indexdir) {
1135 /*
1136 * Verify upper root is exclusively associated with index dir.
1137 * Older kernels stored upper fh in "trusted.overlay.origin"
1138 * xattr. If that xattr exists, verify that it is a match to
1139 * upper dir file handle. In any case, verify or set xattr
1140 * "trusted.overlay.upper" to indicate that index may have
1141 * directory entries.
1142 */
1143 if (ovl_check_origin_xattr(ofs->indexdir)) {
1144 err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN,
1145 upperpath->dentry, true, false);
1146 if (err)
1147 pr_err("overlayfs: failed to verify index dir 'origin' xattr\n");
1148 }
1149 err = ovl_verify_upper(ofs->indexdir, upperpath->dentry, true);
1150 if (err)
1151 pr_err("overlayfs: failed to verify index dir 'upper' xattr\n");
1152
1153 /* Cleanup bad/stale/orphan index entries */
1154 if (!err)
1155 err = ovl_indexdir_cleanup(ofs);
1156 }
1157 if (err || !ofs->indexdir)
1158 pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
1159
1160 out:
1161 mnt_drop_write(mnt);
1162 return err;
1163 }
1164
1165 /* Get a unique fsid for the layer */
1166 static int ovl_get_fsid(struct ovl_fs *ofs, struct super_block *sb)
1167 {
1168 unsigned int i;
1169 dev_t dev;
1170 int err;
1171
1172 /* fsid 0 is reserved for upper fs even with non upper overlay */
1173 if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb == sb)
1174 return 0;
1175
1176 for (i = 0; i < ofs->numlowerfs; i++) {
1177 if (ofs->lower_fs[i].sb == sb)
1178 return i + 1;
1179 }
1180
1181 err = get_anon_bdev(&dev);
1182 if (err) {
1183 pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
1184 return err;
1185 }
1186
1187 ofs->lower_fs[ofs->numlowerfs].sb = sb;
1188 ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev;
1189 ofs->numlowerfs++;
1190
1191 return ofs->numlowerfs;
1192 }
1193
1194 static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack,
1195 unsigned int numlower)
1196 {
1197 int err;
1198 unsigned int i;
1199
1200 err = -ENOMEM;
1201 ofs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer),
1202 GFP_KERNEL);
1203 if (ofs->lower_layers == NULL)
1204 goto out;
1205
1206 ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb),
1207 GFP_KERNEL);
1208 if (ofs->lower_fs == NULL)
1209 goto out;
1210
1211 for (i = 0; i < numlower; i++) {
1212 struct vfsmount *mnt;
1213 int fsid;
1214
1215 err = fsid = ovl_get_fsid(ofs, stack[i].mnt->mnt_sb);
1216 if (err < 0)
1217 goto out;
1218
1219 mnt = clone_private_mount(&stack[i]);
1220 err = PTR_ERR(mnt);
1221 if (IS_ERR(mnt)) {
1222 pr_err("overlayfs: failed to clone lowerpath\n");
1223 goto out;
1224 }
1225
1226 /*
1227 * Make lower layers R/O. That way fchmod/fchown on lower file
1228 * will fail instead of modifying lower fs.
1229 */
1230 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
1231
1232 ofs->lower_layers[ofs->numlower].mnt = mnt;
1233 ofs->lower_layers[ofs->numlower].idx = i + 1;
1234 ofs->lower_layers[ofs->numlower].fsid = fsid;
1235 if (fsid) {
1236 ofs->lower_layers[ofs->numlower].fs =
1237 &ofs->lower_fs[fsid - 1];
1238 }
1239 ofs->numlower++;
1240 }
1241
1242 /*
1243 * When all layers on same fs, overlay can use real inode numbers.
1244 * With mount option "xino=on", mounter declares that there are enough
1245 * free high bits in underlying fs to hold the unique fsid.
1246 * If overlayfs does encounter underlying inodes using the high xino
1247 * bits reserved for fsid, it emits a warning and uses the original
1248 * inode number.
1249 */
1250 if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) {
1251 ofs->xino_bits = 0;
1252 ofs->config.xino = OVL_XINO_OFF;
1253 } else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) {
1254 /*
1255 * This is a roundup of number of bits needed for numlowerfs+1
1256 * (i.e. ilog2(numlowerfs+1 - 1) + 1). fsid 0 is reserved for
1257 * upper fs even with non upper overlay.
1258 */
1259 BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31);
1260 ofs->xino_bits = ilog2(ofs->numlowerfs) + 1;
1261 }
1262
1263 if (ofs->xino_bits) {
1264 pr_info("overlayfs: \"xino\" feature enabled using %d upper inode bits.\n",
1265 ofs->xino_bits);
1266 }
1267
1268 err = 0;
1269 out:
1270 return err;
1271 }
1272
1273 static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
1274 struct ovl_fs *ofs)
1275 {
1276 int err;
1277 char *lowertmp, *lower;
1278 struct path *stack = NULL;
1279 unsigned int stacklen, numlower = 0, i;
1280 bool remote = false;
1281 struct ovl_entry *oe;
1282
1283 err = -ENOMEM;
1284 lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
1285 if (!lowertmp)
1286 goto out_err;
1287
1288 err = -EINVAL;
1289 stacklen = ovl_split_lowerdirs(lowertmp);
1290 if (stacklen > OVL_MAX_STACK) {
1291 pr_err("overlayfs: too many lower directories, limit is %d\n",
1292 OVL_MAX_STACK);
1293 goto out_err;
1294 } else if (!ofs->config.upperdir && stacklen == 1) {
1295 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
1296 goto out_err;
1297 } else if (!ofs->config.upperdir && ofs->config.nfs_export &&
1298 ofs->config.redirect_follow) {
1299 pr_warn("overlayfs: NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
1300 ofs->config.nfs_export = false;
1301 }
1302
1303 err = -ENOMEM;
1304 stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
1305 if (!stack)
1306 goto out_err;
1307
1308 err = -EINVAL;
1309 lower = lowertmp;
1310 for (numlower = 0; numlower < stacklen; numlower++) {
1311 err = ovl_lower_dir(lower, &stack[numlower], ofs,
1312 &sb->s_stack_depth, &remote);
1313 if (err)
1314 goto out_err;
1315
1316 lower = strchr(lower, '\0') + 1;
1317 }
1318
1319 err = -EINVAL;
1320 sb->s_stack_depth++;
1321 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
1322 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
1323 goto out_err;
1324 }
1325
1326 err = ovl_get_lower_layers(ofs, stack, numlower);
1327 if (err)
1328 goto out_err;
1329
1330 err = -ENOMEM;
1331 oe = ovl_alloc_entry(numlower);
1332 if (!oe)
1333 goto out_err;
1334
1335 for (i = 0; i < numlower; i++) {
1336 oe->lowerstack[i].dentry = dget(stack[i].dentry);
1337 oe->lowerstack[i].layer = &ofs->lower_layers[i];
1338 }
1339
1340 if (remote)
1341 sb->s_d_op = &ovl_reval_dentry_operations;
1342 else
1343 sb->s_d_op = &ovl_dentry_operations;
1344
1345 out:
1346 for (i = 0; i < numlower; i++)
1347 path_put(&stack[i]);
1348 kfree(stack);
1349 kfree(lowertmp);
1350
1351 return oe;
1352
1353 out_err:
1354 oe = ERR_PTR(err);
1355 goto out;
1356 }
1357
1358 static int ovl_fill_super(struct super_block *sb, void *data, int silent)
1359 {
1360 struct path upperpath = { };
1361 struct dentry *root_dentry;
1362 struct ovl_entry *oe;
1363 struct ovl_fs *ofs;
1364 struct cred *cred;
1365 int err;
1366
1367 err = -ENOMEM;
1368 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
1369 if (!ofs)
1370 goto out;
1371
1372 ofs->creator_cred = cred = prepare_creds();
1373 if (!cred)
1374 goto out_err;
1375
1376 ofs->config.index = ovl_index_def;
1377 ofs->config.nfs_export = ovl_nfs_export_def;
1378 ofs->config.xino = ovl_xino_def();
1379 err = ovl_parse_opt((char *) data, &ofs->config);
1380 if (err)
1381 goto out_err;
1382
1383 err = -EINVAL;
1384 if (!ofs->config.lowerdir) {
1385 if (!silent)
1386 pr_err("overlayfs: missing 'lowerdir'\n");
1387 goto out_err;
1388 }
1389
1390 sb->s_stack_depth = 0;
1391 sb->s_maxbytes = MAX_LFS_FILESIZE;
1392 /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
1393 if (ofs->config.xino != OVL_XINO_OFF)
1394 ofs->xino_bits = BITS_PER_LONG - 32;
1395
1396 if (ofs->config.upperdir) {
1397 if (!ofs->config.workdir) {
1398 pr_err("overlayfs: missing 'workdir'\n");
1399 goto out_err;
1400 }
1401
1402 err = ovl_get_upper(ofs, &upperpath);
1403 if (err)
1404 goto out_err;
1405
1406 err = ovl_get_workdir(ofs, &upperpath);
1407 if (err)
1408 goto out_err;
1409
1410 if (!ofs->workdir)
1411 sb->s_flags |= SB_RDONLY;
1412
1413 sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth;
1414 sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran;
1415
1416 }
1417 oe = ovl_get_lowerstack(sb, ofs);
1418 err = PTR_ERR(oe);
1419 if (IS_ERR(oe))
1420 goto out_err;
1421
1422 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1423 if (!ofs->upper_mnt)
1424 sb->s_flags |= SB_RDONLY;
1425
1426 if (!(ovl_force_readonly(ofs)) && ofs->config.index) {
1427 err = ovl_get_indexdir(ofs, oe, &upperpath);
1428 if (err)
1429 goto out_free_oe;
1430
1431 /* Force r/o mount with no index dir */
1432 if (!ofs->indexdir) {
1433 dput(ofs->workdir);
1434 ofs->workdir = NULL;
1435 sb->s_flags |= SB_RDONLY;
1436 }
1437
1438 }
1439
1440 /* Show index=off in /proc/mounts for forced r/o mount */
1441 if (!ofs->indexdir) {
1442 ofs->config.index = false;
1443 if (ofs->upper_mnt && ofs->config.nfs_export) {
1444 pr_warn("overlayfs: NFS export requires an index dir, falling back to nfs_export=off.\n");
1445 ofs->config.nfs_export = false;
1446 }
1447 }
1448
1449 if (ofs->config.nfs_export)
1450 sb->s_export_op = &ovl_export_operations;
1451
1452 /* Never override disk quota limits or use reserved space */
1453 cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
1454
1455 sb->s_magic = OVERLAYFS_SUPER_MAGIC;
1456 sb->s_op = &ovl_super_operations;
1457 sb->s_xattr = ovl_xattr_handlers;
1458 sb->s_fs_info = ofs;
1459 sb->s_flags |= SB_POSIXACL | SB_NOREMOTELOCK;
1460
1461 err = -ENOMEM;
1462 root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
1463 if (!root_dentry)
1464 goto out_free_oe;
1465
1466 root_dentry->d_fsdata = oe;
1467
1468 mntput(upperpath.mnt);
1469 if (upperpath.dentry) {
1470 ovl_dentry_set_upper_alias(root_dentry);
1471 if (ovl_is_impuredir(upperpath.dentry))
1472 ovl_set_flag(OVL_IMPURE, d_inode(root_dentry));
1473 }
1474
1475 /* Root is always merge -> can have whiteouts */
1476 ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry));
1477 ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
1478 ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
1479 ovl_dentry_lower(root_dentry));
1480
1481 sb->s_root = root_dentry;
1482
1483 return 0;
1484
1485 out_free_oe:
1486 ovl_entry_stack_free(oe);
1487 kfree(oe);
1488 out_err:
1489 path_put(&upperpath);
1490 ovl_free_fs(ofs);
1491 out:
1492 return err;
1493 }
1494
1495 static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
1496 const char *dev_name, void *raw_data)
1497 {
1498 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
1499 }
1500
1501 static struct file_system_type ovl_fs_type = {
1502 .owner = THIS_MODULE,
1503 .name = "overlay",
1504 .mount = ovl_mount,
1505 .kill_sb = kill_anon_super,
1506 };
1507 MODULE_ALIAS_FS("overlay");
1508
1509 static void ovl_inode_init_once(void *foo)
1510 {
1511 struct ovl_inode *oi = foo;
1512
1513 inode_init_once(&oi->vfs_inode);
1514 }
1515
1516 static int __init ovl_init(void)
1517 {
1518 int err;
1519
1520 ovl_inode_cachep = kmem_cache_create("ovl_inode",
1521 sizeof(struct ovl_inode), 0,
1522 (SLAB_RECLAIM_ACCOUNT|
1523 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
1524 ovl_inode_init_once);
1525 if (ovl_inode_cachep == NULL)
1526 return -ENOMEM;
1527
1528 err = register_filesystem(&ovl_fs_type);
1529 if (err)
1530 kmem_cache_destroy(ovl_inode_cachep);
1531
1532 return err;
1533 }
1534
1535 static void __exit ovl_exit(void)
1536 {
1537 unregister_filesystem(&ovl_fs_type);
1538
1539 /*
1540 * Make sure all delayed rcu free inodes are flushed before we
1541 * destroy cache.
1542 */
1543 rcu_barrier();
1544 kmem_cache_destroy(ovl_inode_cachep);
1545
1546 }
1547
1548 module_init(ovl_init);
1549 module_exit(ovl_exit);
Linux with added FPC-III support