arm64: kgdb: Fix single-step exception handling oops
[linux/fpc-iii.git] / fs / overlayfs / readdir.c
bloba1be6baabca35a2a68469ed735886236aeaa3169
1 /*
3 * Copyright (C) 2011 Novell Inc.
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 */
10 #include <linux/fs.h>
11 #include <linux/slab.h>
12 #include <linux/namei.h>
13 #include <linux/file.h>
14 #include <linux/xattr.h>
15 #include <linux/rbtree.h>
16 #include <linux/security.h>
17 #include <linux/cred.h>
18 #include "overlayfs.h"
20 struct ovl_cache_entry {
21 unsigned int len;
22 unsigned int type;
23 u64 ino;
24 struct list_head l_node;
25 struct rb_node node;
26 struct ovl_cache_entry *next_maybe_whiteout;
27 bool is_whiteout;
28 char name[];
31 struct ovl_dir_cache {
32 long refcount;
33 u64 version;
34 struct list_head entries;
37 struct ovl_readdir_data {
38 struct dir_context ctx;
39 struct dentry *dentry;
40 bool is_lowest;
41 struct rb_root root;
42 struct list_head *list;
43 struct list_head middle;
44 struct ovl_cache_entry *first_maybe_whiteout;
45 int count;
46 int err;
47 bool d_type_supported;
50 struct ovl_dir_file {
51 bool is_real;
52 bool is_upper;
53 struct ovl_dir_cache *cache;
54 struct list_head *cursor;
55 struct file *realfile;
56 struct file *upperfile;
59 static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
61 return container_of(n, struct ovl_cache_entry, node);
64 static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
65 const char *name, int len)
67 struct rb_node *node = root->rb_node;
68 int cmp;
70 while (node) {
71 struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
73 cmp = strncmp(name, p->name, len);
74 if (cmp > 0)
75 node = p->node.rb_right;
76 else if (cmp < 0 || len < p->len)
77 node = p->node.rb_left;
78 else
79 return p;
82 return NULL;
85 static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
86 const char *name, int len,
87 u64 ino, unsigned int d_type)
89 struct ovl_cache_entry *p;
90 size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
92 p = kmalloc(size, GFP_KERNEL);
93 if (!p)
94 return NULL;
96 memcpy(p->name, name, len);
97 p->name[len] = '\0';
98 p->len = len;
99 p->type = d_type;
100 p->ino = ino;
101 p->is_whiteout = false;
103 if (d_type == DT_CHR) {
104 p->next_maybe_whiteout = rdd->first_maybe_whiteout;
105 rdd->first_maybe_whiteout = p;
107 return p;
110 static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
111 const char *name, int len, u64 ino,
112 unsigned int d_type)
114 struct rb_node **newp = &rdd->root.rb_node;
115 struct rb_node *parent = NULL;
116 struct ovl_cache_entry *p;
118 while (*newp) {
119 int cmp;
120 struct ovl_cache_entry *tmp;
122 parent = *newp;
123 tmp = ovl_cache_entry_from_node(*newp);
124 cmp = strncmp(name, tmp->name, len);
125 if (cmp > 0)
126 newp = &tmp->node.rb_right;
127 else if (cmp < 0 || len < tmp->len)
128 newp = &tmp->node.rb_left;
129 else
130 return 0;
133 p = ovl_cache_entry_new(rdd, name, len, ino, d_type);
134 if (p == NULL)
135 return -ENOMEM;
137 list_add_tail(&p->l_node, rdd->list);
138 rb_link_node(&p->node, parent, newp);
139 rb_insert_color(&p->node, &rdd->root);
141 return 0;
144 static int ovl_fill_lowest(struct ovl_readdir_data *rdd,
145 const char *name, int namelen,
146 loff_t offset, u64 ino, unsigned int d_type)
148 struct ovl_cache_entry *p;
150 p = ovl_cache_entry_find(&rdd->root, name, namelen);
151 if (p) {
152 list_move_tail(&p->l_node, &rdd->middle);
153 } else {
154 p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
155 if (p == NULL)
156 rdd->err = -ENOMEM;
157 else
158 list_add_tail(&p->l_node, &rdd->middle);
161 return rdd->err;
164 void ovl_cache_free(struct list_head *list)
166 struct ovl_cache_entry *p;
167 struct ovl_cache_entry *n;
169 list_for_each_entry_safe(p, n, list, l_node)
170 kfree(p);
172 INIT_LIST_HEAD(list);
175 static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry)
177 struct ovl_dir_cache *cache = od->cache;
179 WARN_ON(cache->refcount <= 0);
180 cache->refcount--;
181 if (!cache->refcount) {
182 if (ovl_dir_cache(dentry) == cache)
183 ovl_set_dir_cache(dentry, NULL);
185 ovl_cache_free(&cache->entries);
186 kfree(cache);
190 static int ovl_fill_merge(struct dir_context *ctx, const char *name,
191 int namelen, loff_t offset, u64 ino,
192 unsigned int d_type)
194 struct ovl_readdir_data *rdd =
195 container_of(ctx, struct ovl_readdir_data, ctx);
197 rdd->count++;
198 if (!rdd->is_lowest)
199 return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
200 else
201 return ovl_fill_lowest(rdd, name, namelen, offset, ino, d_type);
204 static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)
206 int err;
207 struct ovl_cache_entry *p;
208 struct dentry *dentry;
209 const struct cred *old_cred;
211 old_cred = ovl_override_creds(rdd->dentry->d_sb);
213 err = down_write_killable(&dir->d_inode->i_rwsem);
214 if (!err) {
215 while (rdd->first_maybe_whiteout) {
216 p = rdd->first_maybe_whiteout;
217 rdd->first_maybe_whiteout = p->next_maybe_whiteout;
218 dentry = lookup_one_len(p->name, dir, p->len);
219 if (!IS_ERR(dentry)) {
220 p->is_whiteout = ovl_is_whiteout(dentry);
221 dput(dentry);
224 inode_unlock(dir->d_inode);
226 revert_creds(old_cred);
228 return err;
231 static inline int ovl_dir_read(struct path *realpath,
232 struct ovl_readdir_data *rdd)
234 struct file *realfile;
235 int err;
237 realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
238 if (IS_ERR(realfile))
239 return PTR_ERR(realfile);
241 rdd->first_maybe_whiteout = NULL;
242 rdd->ctx.pos = 0;
243 do {
244 rdd->count = 0;
245 rdd->err = 0;
246 err = iterate_dir(realfile, &rdd->ctx);
247 if (err >= 0)
248 err = rdd->err;
249 } while (!err && rdd->count);
251 if (!err && rdd->first_maybe_whiteout && rdd->dentry)
252 err = ovl_check_whiteouts(realpath->dentry, rdd);
254 fput(realfile);
256 return err;
259 static void ovl_dir_reset(struct file *file)
261 struct ovl_dir_file *od = file->private_data;
262 struct ovl_dir_cache *cache = od->cache;
263 struct dentry *dentry = file->f_path.dentry;
264 enum ovl_path_type type = ovl_path_type(dentry);
266 if (cache && ovl_dentry_version_get(dentry) != cache->version) {
267 ovl_cache_put(od, dentry);
268 od->cache = NULL;
269 od->cursor = NULL;
271 WARN_ON(!od->is_real && !OVL_TYPE_MERGE(type));
272 if (od->is_real && OVL_TYPE_MERGE(type))
273 od->is_real = false;
276 static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list)
278 int err;
279 struct path realpath;
280 struct ovl_readdir_data rdd = {
281 .ctx.actor = ovl_fill_merge,
282 .dentry = dentry,
283 .list = list,
284 .root = RB_ROOT,
285 .is_lowest = false,
287 int idx, next;
289 for (idx = 0; idx != -1; idx = next) {
290 next = ovl_path_next(idx, dentry, &realpath);
292 if (next != -1) {
293 err = ovl_dir_read(&realpath, &rdd);
294 if (err)
295 break;
296 } else {
298 * Insert lowest layer entries before upper ones, this
299 * allows offsets to be reasonably constant
301 list_add(&rdd.middle, rdd.list);
302 rdd.is_lowest = true;
303 err = ovl_dir_read(&realpath, &rdd);
304 list_del(&rdd.middle);
307 return err;
310 static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
312 struct list_head *p;
313 loff_t off = 0;
315 list_for_each(p, &od->cache->entries) {
316 if (off >= pos)
317 break;
318 off++;
320 /* Cursor is safe since the cache is stable */
321 od->cursor = p;
324 static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
326 int res;
327 struct ovl_dir_cache *cache;
329 cache = ovl_dir_cache(dentry);
330 if (cache && ovl_dentry_version_get(dentry) == cache->version) {
331 cache->refcount++;
332 return cache;
334 ovl_set_dir_cache(dentry, NULL);
336 cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
337 if (!cache)
338 return ERR_PTR(-ENOMEM);
340 cache->refcount = 1;
341 INIT_LIST_HEAD(&cache->entries);
343 res = ovl_dir_read_merged(dentry, &cache->entries);
344 if (res) {
345 ovl_cache_free(&cache->entries);
346 kfree(cache);
347 return ERR_PTR(res);
350 cache->version = ovl_dentry_version_get(dentry);
351 ovl_set_dir_cache(dentry, cache);
353 return cache;
356 static int ovl_iterate(struct file *file, struct dir_context *ctx)
358 struct ovl_dir_file *od = file->private_data;
359 struct dentry *dentry = file->f_path.dentry;
360 struct ovl_cache_entry *p;
362 if (!ctx->pos)
363 ovl_dir_reset(file);
365 if (od->is_real)
366 return iterate_dir(od->realfile, ctx);
368 if (!od->cache) {
369 struct ovl_dir_cache *cache;
371 cache = ovl_cache_get(dentry);
372 if (IS_ERR(cache))
373 return PTR_ERR(cache);
375 od->cache = cache;
376 ovl_seek_cursor(od, ctx->pos);
379 while (od->cursor != &od->cache->entries) {
380 p = list_entry(od->cursor, struct ovl_cache_entry, l_node);
381 if (!p->is_whiteout)
382 if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
383 break;
384 od->cursor = p->l_node.next;
385 ctx->pos++;
387 return 0;
390 static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
392 loff_t res;
393 struct ovl_dir_file *od = file->private_data;
395 inode_lock(file_inode(file));
396 if (!file->f_pos)
397 ovl_dir_reset(file);
399 if (od->is_real) {
400 res = vfs_llseek(od->realfile, offset, origin);
401 file->f_pos = od->realfile->f_pos;
402 } else {
403 res = -EINVAL;
405 switch (origin) {
406 case SEEK_CUR:
407 offset += file->f_pos;
408 break;
409 case SEEK_SET:
410 break;
411 default:
412 goto out_unlock;
414 if (offset < 0)
415 goto out_unlock;
417 if (offset != file->f_pos) {
418 file->f_pos = offset;
419 if (od->cache)
420 ovl_seek_cursor(od, offset);
422 res = offset;
424 out_unlock:
425 inode_unlock(file_inode(file));
427 return res;
430 static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
431 int datasync)
433 struct ovl_dir_file *od = file->private_data;
434 struct dentry *dentry = file->f_path.dentry;
435 struct file *realfile = od->realfile;
437 /* Nothing to sync for lower */
438 if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
439 return 0;
442 * Need to check if we started out being a lower dir, but got copied up
444 if (!od->is_upper) {
445 struct inode *inode = file_inode(file);
447 realfile = lockless_dereference(od->upperfile);
448 if (!realfile) {
449 struct path upperpath;
451 ovl_path_upper(dentry, &upperpath);
452 realfile = ovl_path_open(&upperpath, O_RDONLY);
453 smp_mb__before_spinlock();
454 inode_lock(inode);
455 if (!od->upperfile) {
456 if (IS_ERR(realfile)) {
457 inode_unlock(inode);
458 return PTR_ERR(realfile);
460 od->upperfile = realfile;
461 } else {
462 /* somebody has beaten us to it */
463 if (!IS_ERR(realfile))
464 fput(realfile);
465 realfile = od->upperfile;
467 inode_unlock(inode);
471 return vfs_fsync_range(realfile, start, end, datasync);
474 static int ovl_dir_release(struct inode *inode, struct file *file)
476 struct ovl_dir_file *od = file->private_data;
478 if (od->cache) {
479 inode_lock(inode);
480 ovl_cache_put(od, file->f_path.dentry);
481 inode_unlock(inode);
483 fput(od->realfile);
484 if (od->upperfile)
485 fput(od->upperfile);
486 kfree(od);
488 return 0;
491 static int ovl_dir_open(struct inode *inode, struct file *file)
493 struct path realpath;
494 struct file *realfile;
495 struct ovl_dir_file *od;
496 enum ovl_path_type type;
498 od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
499 if (!od)
500 return -ENOMEM;
502 type = ovl_path_real(file->f_path.dentry, &realpath);
503 realfile = ovl_path_open(&realpath, file->f_flags);
504 if (IS_ERR(realfile)) {
505 kfree(od);
506 return PTR_ERR(realfile);
508 od->realfile = realfile;
509 od->is_real = !OVL_TYPE_MERGE(type);
510 od->is_upper = OVL_TYPE_UPPER(type);
511 file->private_data = od;
513 return 0;
516 const struct file_operations ovl_dir_operations = {
517 .read = generic_read_dir,
518 .open = ovl_dir_open,
519 .iterate = ovl_iterate,
520 .llseek = ovl_dir_llseek,
521 .fsync = ovl_dir_fsync,
522 .release = ovl_dir_release,
525 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
527 int err;
528 struct ovl_cache_entry *p;
530 err = ovl_dir_read_merged(dentry, list);
531 if (err)
532 return err;
534 err = 0;
536 list_for_each_entry(p, list, l_node) {
537 if (p->is_whiteout)
538 continue;
540 if (p->name[0] == '.') {
541 if (p->len == 1)
542 continue;
543 if (p->len == 2 && p->name[1] == '.')
544 continue;
546 err = -ENOTEMPTY;
547 break;
550 return err;
553 void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
555 struct ovl_cache_entry *p;
557 inode_lock_nested(upper->d_inode, I_MUTEX_CHILD);
558 list_for_each_entry(p, list, l_node) {
559 struct dentry *dentry;
561 if (!p->is_whiteout)
562 continue;
564 dentry = lookup_one_len(p->name, upper, p->len);
565 if (IS_ERR(dentry)) {
566 pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n",
567 upper->d_name.name, p->len, p->name,
568 (int) PTR_ERR(dentry));
569 continue;
571 if (dentry->d_inode)
572 ovl_cleanup(upper->d_inode, dentry);
573 dput(dentry);
575 inode_unlock(upper->d_inode);
578 static int ovl_check_d_type(struct dir_context *ctx, const char *name,
579 int namelen, loff_t offset, u64 ino,
580 unsigned int d_type)
582 struct ovl_readdir_data *rdd =
583 container_of(ctx, struct ovl_readdir_data, ctx);
585 /* Even if d_type is not supported, DT_DIR is returned for . and .. */
586 if (!strncmp(name, ".", namelen) || !strncmp(name, "..", namelen))
587 return 0;
589 if (d_type != DT_UNKNOWN)
590 rdd->d_type_supported = true;
592 return 0;
596 * Returns 1 if d_type is supported, 0 not supported/unknown. Negative values
597 * if error is encountered.
599 int ovl_check_d_type_supported(struct path *realpath)
601 int err;
602 struct ovl_readdir_data rdd = {
603 .ctx.actor = ovl_check_d_type,
604 .d_type_supported = false,
607 err = ovl_dir_read(realpath, &rdd);
608 if (err)
609 return err;
611 return rdd.d_type_supported;
614 static void ovl_workdir_cleanup_recurse(struct path *path, int level)
616 int err;
617 struct inode *dir = path->dentry->d_inode;
618 LIST_HEAD(list);
619 struct ovl_cache_entry *p;
620 struct ovl_readdir_data rdd = {
621 .ctx.actor = ovl_fill_merge,
622 .dentry = NULL,
623 .list = &list,
624 .root = RB_ROOT,
625 .is_lowest = false,
628 err = ovl_dir_read(path, &rdd);
629 if (err)
630 goto out;
632 inode_lock_nested(dir, I_MUTEX_PARENT);
633 list_for_each_entry(p, &list, l_node) {
634 struct dentry *dentry;
636 if (p->name[0] == '.') {
637 if (p->len == 1)
638 continue;
639 if (p->len == 2 && p->name[1] == '.')
640 continue;
642 dentry = lookup_one_len(p->name, path->dentry, p->len);
643 if (IS_ERR(dentry))
644 continue;
645 if (dentry->d_inode)
646 ovl_workdir_cleanup(dir, path->mnt, dentry, level);
647 dput(dentry);
649 inode_unlock(dir);
650 out:
651 ovl_cache_free(&list);
654 void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
655 struct dentry *dentry, int level)
657 int err;
659 if (!d_is_dir(dentry) || level > 1) {
660 ovl_cleanup(dir, dentry);
661 return;
664 err = ovl_do_rmdir(dir, dentry);
665 if (err) {
666 struct path path = { .mnt = mnt, .dentry = dentry };
668 inode_unlock(dir);
669 ovl_workdir_cleanup_recurse(&path, level + 1);
670 inode_lock_nested(dir, I_MUTEX_PARENT);
671 ovl_cleanup(dir, dentry);