xref: /openbmc/linux/fs/reiserfs/xattr.c (revision fff74a93)
1 /*
2  * linux/fs/reiserfs/xattr.c
3  *
4  * Copyright (c) 2002 by Jeff Mahoney, <jeffm@suse.com>
5  *
6  */
7 
8 /*
9  * In order to implement EA/ACLs in a clean, backwards compatible manner,
10  * they are implemented as files in a "private" directory.
11  * Each EA is in it's own file, with the directory layout like so (/ is assumed
12  * to be relative to fs root). Inside the /.reiserfs_priv/xattrs directory,
13  * directories named using the capital-hex form of the objectid and
14  * generation number are used. Inside each directory are individual files
15  * named with the name of the extended attribute.
16  *
17  * So, for objectid 12648430, we could have:
18  * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_access
19  * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_default
20  * /.reiserfs_priv/xattrs/C0FFEE.0/user.Content-Type
21  * .. or similar.
22  *
23  * The file contents are the text of the EA. The size is known based on the
24  * stat data describing the file.
25  *
26  * In the case of system.posix_acl_access and system.posix_acl_default, since
27  * these are special cases for filesystem ACLs, they are interpreted by the
28  * kernel, in addition, they are negatively and positively cached and attached
29  * to the inode so that unnecessary lookups are avoided.
30  *
31  * Locking works like so:
32  * Directory components (xattr root, xattr dir) are protectd by their i_mutex.
33  * The xattrs themselves are protected by the xattr_sem.
34  */
35 
36 #include "reiserfs.h"
37 #include <linux/capability.h>
38 #include <linux/dcache.h>
39 #include <linux/namei.h>
40 #include <linux/errno.h>
41 #include <linux/gfp.h>
42 #include <linux/fs.h>
43 #include <linux/file.h>
44 #include <linux/pagemap.h>
45 #include <linux/xattr.h>
46 #include "xattr.h"
47 #include "acl.h"
48 #include <linux/uaccess.h>
49 #include <net/checksum.h>
50 #include <linux/stat.h>
51 #include <linux/quotaops.h>
52 #include <linux/security.h>
53 #include <linux/posix_acl_xattr.h>
54 
55 #define PRIVROOT_NAME ".reiserfs_priv"
56 #define XAROOT_NAME   "xattrs"
57 
58 
59 /*
60  * Helpers for inode ops. We do this so that we don't have all the VFS
61  * overhead and also for proper i_mutex annotation.
62  * dir->i_mutex must be held for all of them.
63  */
64 #ifdef CONFIG_REISERFS_FS_XATTR
65 static int xattr_create(struct inode *dir, struct dentry *dentry, int mode)
66 {
67 	BUG_ON(!mutex_is_locked(&dir->i_mutex));
68 	return dir->i_op->create(dir, dentry, mode, true);
69 }
70 #endif
71 
72 static int xattr_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
73 {
74 	BUG_ON(!mutex_is_locked(&dir->i_mutex));
75 	return dir->i_op->mkdir(dir, dentry, mode);
76 }
77 
78 /*
79  * We use I_MUTEX_CHILD here to silence lockdep. It's safe because xattr
80  * mutation ops aren't called during rename or splace, which are the
81  * only other users of I_MUTEX_CHILD. It violates the ordering, but that's
82  * better than allocating another subclass just for this code.
83  */
84 static int xattr_unlink(struct inode *dir, struct dentry *dentry)
85 {
86 	int error;
87 
88 	BUG_ON(!mutex_is_locked(&dir->i_mutex));
89 
90 	mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
91 	error = dir->i_op->unlink(dir, dentry);
92 	mutex_unlock(&dentry->d_inode->i_mutex);
93 
94 	if (!error)
95 		d_delete(dentry);
96 	return error;
97 }
98 
99 static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
100 {
101 	int error;
102 
103 	BUG_ON(!mutex_is_locked(&dir->i_mutex));
104 
105 	mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
106 	error = dir->i_op->rmdir(dir, dentry);
107 	if (!error)
108 		dentry->d_inode->i_flags |= S_DEAD;
109 	mutex_unlock(&dentry->d_inode->i_mutex);
110 	if (!error)
111 		d_delete(dentry);
112 
113 	return error;
114 }
115 
116 #define xattr_may_create(flags)	(!flags || flags & XATTR_CREATE)
117 
118 static struct dentry *open_xa_root(struct super_block *sb, int flags)
119 {
120 	struct dentry *privroot = REISERFS_SB(sb)->priv_root;
121 	struct dentry *xaroot;
122 
123 	if (!privroot->d_inode)
124 		return ERR_PTR(-ENODATA);
125 
126 	mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
127 
128 	xaroot = dget(REISERFS_SB(sb)->xattr_root);
129 	if (!xaroot)
130 		xaroot = ERR_PTR(-ENODATA);
131 	else if (!xaroot->d_inode) {
132 		int err = -ENODATA;
133 
134 		if (xattr_may_create(flags))
135 			err = xattr_mkdir(privroot->d_inode, xaroot, 0700);
136 		if (err) {
137 			dput(xaroot);
138 			xaroot = ERR_PTR(err);
139 		}
140 	}
141 
142 	mutex_unlock(&privroot->d_inode->i_mutex);
143 	return xaroot;
144 }
145 
146 static struct dentry *open_xa_dir(const struct inode *inode, int flags)
147 {
148 	struct dentry *xaroot, *xadir;
149 	char namebuf[17];
150 
151 	xaroot = open_xa_root(inode->i_sb, flags);
152 	if (IS_ERR(xaroot))
153 		return xaroot;
154 
155 	snprintf(namebuf, sizeof(namebuf), "%X.%X",
156 		 le32_to_cpu(INODE_PKEY(inode)->k_objectid),
157 		 inode->i_generation);
158 
159 	mutex_lock_nested(&xaroot->d_inode->i_mutex, I_MUTEX_XATTR);
160 
161 	xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
162 	if (!IS_ERR(xadir) && !xadir->d_inode) {
163 		int err = -ENODATA;
164 
165 		if (xattr_may_create(flags))
166 			err = xattr_mkdir(xaroot->d_inode, xadir, 0700);
167 		if (err) {
168 			dput(xadir);
169 			xadir = ERR_PTR(err);
170 		}
171 	}
172 
173 	mutex_unlock(&xaroot->d_inode->i_mutex);
174 	dput(xaroot);
175 	return xadir;
176 }
177 
178 /*
179  * The following are side effects of other operations that aren't explicitly
180  * modifying extended attributes. This includes operations such as permissions
181  * or ownership changes, object deletions, etc.
182  */
183 struct reiserfs_dentry_buf {
184 	struct dir_context ctx;
185 	struct dentry *xadir;
186 	int count;
187 	struct dentry *dentries[8];
188 };
189 
190 static int
191 fill_with_dentries(void *buf, const char *name, int namelen, loff_t offset,
192 		    u64 ino, unsigned int d_type)
193 {
194 	struct reiserfs_dentry_buf *dbuf = buf;
195 	struct dentry *dentry;
196 
197 	WARN_ON_ONCE(!mutex_is_locked(&dbuf->xadir->d_inode->i_mutex));
198 
199 	if (dbuf->count == ARRAY_SIZE(dbuf->dentries))
200 		return -ENOSPC;
201 
202 	if (name[0] == '.' && (namelen < 2 ||
203 			       (namelen == 2 && name[1] == '.')))
204 		return 0;
205 
206 	dentry = lookup_one_len(name, dbuf->xadir, namelen);
207 	if (IS_ERR(dentry)) {
208 		return PTR_ERR(dentry);
209 	} else if (!dentry->d_inode) {
210 		/* A directory entry exists, but no file? */
211 		reiserfs_error(dentry->d_sb, "xattr-20003",
212 			       "Corrupted directory: xattr %s listed but "
213 			       "not found for file %s.\n",
214 			       dentry->d_name.name, dbuf->xadir->d_name.name);
215 		dput(dentry);
216 		return -EIO;
217 	}
218 
219 	dbuf->dentries[dbuf->count++] = dentry;
220 	return 0;
221 }
222 
223 static void
224 cleanup_dentry_buf(struct reiserfs_dentry_buf *buf)
225 {
226 	int i;
227 
228 	for (i = 0; i < buf->count; i++)
229 		if (buf->dentries[i])
230 			dput(buf->dentries[i]);
231 }
232 
233 static int reiserfs_for_each_xattr(struct inode *inode,
234 				   int (*action)(struct dentry *, void *),
235 				   void *data)
236 {
237 	struct dentry *dir;
238 	int i, err = 0;
239 	struct reiserfs_dentry_buf buf = {
240 		.ctx.actor = fill_with_dentries,
241 	};
242 
243 	/* Skip out, an xattr has no xattrs associated with it */
244 	if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1)
245 		return 0;
246 
247 	dir = open_xa_dir(inode, XATTR_REPLACE);
248 	if (IS_ERR(dir)) {
249 		err = PTR_ERR(dir);
250 		goto out;
251 	} else if (!dir->d_inode) {
252 		err = 0;
253 		goto out_dir;
254 	}
255 
256 	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
257 
258 	buf.xadir = dir;
259 	while (1) {
260 		err = reiserfs_readdir_inode(dir->d_inode, &buf.ctx);
261 		if (err)
262 			break;
263 		if (!buf.count)
264 			break;
265 		for (i = 0; !err && i < buf.count && buf.dentries[i]; i++) {
266 			struct dentry *dentry = buf.dentries[i];
267 
268 			if (!S_ISDIR(dentry->d_inode->i_mode))
269 				err = action(dentry, data);
270 
271 			dput(dentry);
272 			buf.dentries[i] = NULL;
273 		}
274 		if (err)
275 			break;
276 		buf.count = 0;
277 	}
278 	mutex_unlock(&dir->d_inode->i_mutex);
279 
280 	cleanup_dentry_buf(&buf);
281 
282 	if (!err) {
283 		/*
284 		 * We start a transaction here to avoid a ABBA situation
285 		 * between the xattr root's i_mutex and the journal lock.
286 		 * This doesn't incur much additional overhead since the
287 		 * new transaction will just nest inside the
288 		 * outer transaction.
289 		 */
290 		int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 +
291 			     4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb);
292 		struct reiserfs_transaction_handle th;
293 
294 		reiserfs_write_lock(inode->i_sb);
295 		err = journal_begin(&th, inode->i_sb, blocks);
296 		reiserfs_write_unlock(inode->i_sb);
297 		if (!err) {
298 			int jerror;
299 
300 			mutex_lock_nested(&dir->d_parent->d_inode->i_mutex,
301 					  I_MUTEX_XATTR);
302 			err = action(dir, data);
303 			reiserfs_write_lock(inode->i_sb);
304 			jerror = journal_end(&th);
305 			reiserfs_write_unlock(inode->i_sb);
306 			mutex_unlock(&dir->d_parent->d_inode->i_mutex);
307 			err = jerror ?: err;
308 		}
309 	}
310 out_dir:
311 	dput(dir);
312 out:
313 	/* -ENODATA isn't an error */
314 	if (err == -ENODATA)
315 		err = 0;
316 	return err;
317 }
318 
319 static int delete_one_xattr(struct dentry *dentry, void *data)
320 {
321 	struct inode *dir = dentry->d_parent->d_inode;
322 
323 	/* This is the xattr dir, handle specially. */
324 	if (S_ISDIR(dentry->d_inode->i_mode))
325 		return xattr_rmdir(dir, dentry);
326 
327 	return xattr_unlink(dir, dentry);
328 }
329 
330 static int chown_one_xattr(struct dentry *dentry, void *data)
331 {
332 	struct iattr *attrs = data;
333 	int ia_valid = attrs->ia_valid;
334 	int err;
335 
336 	/*
337 	 * We only want the ownership bits. Otherwise, we'll do
338 	 * things like change a directory to a regular file if
339 	 * ATTR_MODE is set.
340 	 */
341 	attrs->ia_valid &= (ATTR_UID|ATTR_GID);
342 	err = reiserfs_setattr(dentry, attrs);
343 	attrs->ia_valid = ia_valid;
344 
345 	return err;
346 }
347 
348 /* No i_mutex, but the inode is unconnected. */
349 int reiserfs_delete_xattrs(struct inode *inode)
350 {
351 	int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL);
352 
353 	if (err)
354 		reiserfs_warning(inode->i_sb, "jdm-20004",
355 				 "Couldn't delete all xattrs (%d)\n", err);
356 	return err;
357 }
358 
359 /* inode->i_mutex: down */
360 int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
361 {
362 	int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs);
363 
364 	if (err)
365 		reiserfs_warning(inode->i_sb, "jdm-20007",
366 				 "Couldn't chown all xattrs (%d)\n", err);
367 	return err;
368 }
369 
370 #ifdef CONFIG_REISERFS_FS_XATTR
371 /*
372  * Returns a dentry corresponding to a specific extended attribute file
373  * for the inode. If flags allow, the file is created. Otherwise, a
374  * valid or negative dentry, or an error is returned.
375  */
376 static struct dentry *xattr_lookup(struct inode *inode, const char *name,
377 				    int flags)
378 {
379 	struct dentry *xadir, *xafile;
380 	int err = 0;
381 
382 	xadir = open_xa_dir(inode, flags);
383 	if (IS_ERR(xadir))
384 		return ERR_CAST(xadir);
385 
386 	mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
387 	xafile = lookup_one_len(name, xadir, strlen(name));
388 	if (IS_ERR(xafile)) {
389 		err = PTR_ERR(xafile);
390 		goto out;
391 	}
392 
393 	if (xafile->d_inode && (flags & XATTR_CREATE))
394 		err = -EEXIST;
395 
396 	if (!xafile->d_inode) {
397 		err = -ENODATA;
398 		if (xattr_may_create(flags))
399 			err = xattr_create(xadir->d_inode, xafile,
400 					      0700|S_IFREG);
401 	}
402 
403 	if (err)
404 		dput(xafile);
405 out:
406 	mutex_unlock(&xadir->d_inode->i_mutex);
407 	dput(xadir);
408 	if (err)
409 		return ERR_PTR(err);
410 	return xafile;
411 }
412 
413 /* Internal operations on file data */
414 static inline void reiserfs_put_page(struct page *page)
415 {
416 	kunmap(page);
417 	page_cache_release(page);
418 }
419 
420 static struct page *reiserfs_get_page(struct inode *dir, size_t n)
421 {
422 	struct address_space *mapping = dir->i_mapping;
423 	struct page *page;
424 	/*
425 	 * We can deadlock if we try to free dentries,
426 	 * and an unlink/rmdir has just occurred - GFP_NOFS avoids this
427 	 */
428 	mapping_set_gfp_mask(mapping, GFP_NOFS);
429 	page = read_mapping_page(mapping, n >> PAGE_CACHE_SHIFT, NULL);
430 	if (!IS_ERR(page)) {
431 		kmap(page);
432 		if (PageError(page))
433 			goto fail;
434 	}
435 	return page;
436 
437 fail:
438 	reiserfs_put_page(page);
439 	return ERR_PTR(-EIO);
440 }
441 
442 static inline __u32 xattr_hash(const char *msg, int len)
443 {
444 	return csum_partial(msg, len, 0);
445 }
446 
447 int reiserfs_commit_write(struct file *f, struct page *page,
448 			  unsigned from, unsigned to);
449 
450 static void update_ctime(struct inode *inode)
451 {
452 	struct timespec now = current_fs_time(inode->i_sb);
453 
454 	if (inode_unhashed(inode) || !inode->i_nlink ||
455 	    timespec_equal(&inode->i_ctime, &now))
456 		return;
457 
458 	inode->i_ctime = CURRENT_TIME_SEC;
459 	mark_inode_dirty(inode);
460 }
461 
462 static int lookup_and_delete_xattr(struct inode *inode, const char *name)
463 {
464 	int err = 0;
465 	struct dentry *dentry, *xadir;
466 
467 	xadir = open_xa_dir(inode, XATTR_REPLACE);
468 	if (IS_ERR(xadir))
469 		return PTR_ERR(xadir);
470 
471 	mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
472 	dentry = lookup_one_len(name, xadir, strlen(name));
473 	if (IS_ERR(dentry)) {
474 		err = PTR_ERR(dentry);
475 		goto out_dput;
476 	}
477 
478 	if (dentry->d_inode) {
479 		err = xattr_unlink(xadir->d_inode, dentry);
480 		update_ctime(inode);
481 	}
482 
483 	dput(dentry);
484 out_dput:
485 	mutex_unlock(&xadir->d_inode->i_mutex);
486 	dput(xadir);
487 	return err;
488 }
489 
490 
491 /* Generic extended attribute operations that can be used by xa plugins */
492 
493 /*
494  * inode->i_mutex: down
495  */
496 int
497 reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
498 			  struct inode *inode, const char *name,
499 			  const void *buffer, size_t buffer_size, int flags)
500 {
501 	int err = 0;
502 	struct dentry *dentry;
503 	struct page *page;
504 	char *data;
505 	size_t file_pos = 0;
506 	size_t buffer_pos = 0;
507 	size_t new_size;
508 	__u32 xahash = 0;
509 
510 	if (get_inode_sd_version(inode) == STAT_DATA_V1)
511 		return -EOPNOTSUPP;
512 
513 	if (!buffer) {
514 		err = lookup_and_delete_xattr(inode, name);
515 		return err;
516 	}
517 
518 	dentry = xattr_lookup(inode, name, flags);
519 	if (IS_ERR(dentry))
520 		return PTR_ERR(dentry);
521 
522 	down_write(&REISERFS_I(inode)->i_xattr_sem);
523 
524 	xahash = xattr_hash(buffer, buffer_size);
525 	while (buffer_pos < buffer_size || buffer_pos == 0) {
526 		size_t chunk;
527 		size_t skip = 0;
528 		size_t page_offset = (file_pos & (PAGE_CACHE_SIZE - 1));
529 
530 		if (buffer_size - buffer_pos > PAGE_CACHE_SIZE)
531 			chunk = PAGE_CACHE_SIZE;
532 		else
533 			chunk = buffer_size - buffer_pos;
534 
535 		page = reiserfs_get_page(dentry->d_inode, file_pos);
536 		if (IS_ERR(page)) {
537 			err = PTR_ERR(page);
538 			goto out_unlock;
539 		}
540 
541 		lock_page(page);
542 		data = page_address(page);
543 
544 		if (file_pos == 0) {
545 			struct reiserfs_xattr_header *rxh;
546 
547 			skip = file_pos = sizeof(struct reiserfs_xattr_header);
548 			if (chunk + skip > PAGE_CACHE_SIZE)
549 				chunk = PAGE_CACHE_SIZE - skip;
550 			rxh = (struct reiserfs_xattr_header *)data;
551 			rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
552 			rxh->h_hash = cpu_to_le32(xahash);
553 		}
554 
555 		reiserfs_write_lock(inode->i_sb);
556 		err = __reiserfs_write_begin(page, page_offset, chunk + skip);
557 		if (!err) {
558 			if (buffer)
559 				memcpy(data + skip, buffer + buffer_pos, chunk);
560 			err = reiserfs_commit_write(NULL, page, page_offset,
561 						    page_offset + chunk +
562 						    skip);
563 		}
564 		reiserfs_write_unlock(inode->i_sb);
565 		unlock_page(page);
566 		reiserfs_put_page(page);
567 		buffer_pos += chunk;
568 		file_pos += chunk;
569 		skip = 0;
570 		if (err || buffer_size == 0 || !buffer)
571 			break;
572 	}
573 
574 	new_size = buffer_size + sizeof(struct reiserfs_xattr_header);
575 	if (!err && new_size < i_size_read(dentry->d_inode)) {
576 		struct iattr newattrs = {
577 			.ia_ctime = current_fs_time(inode->i_sb),
578 			.ia_size = new_size,
579 			.ia_valid = ATTR_SIZE | ATTR_CTIME,
580 		};
581 
582 		mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
583 		inode_dio_wait(dentry->d_inode);
584 
585 		err = reiserfs_setattr(dentry, &newattrs);
586 		mutex_unlock(&dentry->d_inode->i_mutex);
587 	} else
588 		update_ctime(inode);
589 out_unlock:
590 	up_write(&REISERFS_I(inode)->i_xattr_sem);
591 	dput(dentry);
592 	return err;
593 }
594 
595 /* We need to start a transaction to maintain lock ordering */
596 int reiserfs_xattr_set(struct inode *inode, const char *name,
597 		       const void *buffer, size_t buffer_size, int flags)
598 {
599 
600 	struct reiserfs_transaction_handle th;
601 	int error, error2;
602 	size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size);
603 
604 	if (!(flags & XATTR_REPLACE))
605 		jbegin_count += reiserfs_xattr_jcreate_nblocks(inode);
606 
607 	reiserfs_write_lock(inode->i_sb);
608 	error = journal_begin(&th, inode->i_sb, jbegin_count);
609 	reiserfs_write_unlock(inode->i_sb);
610 	if (error) {
611 		return error;
612 	}
613 
614 	error = reiserfs_xattr_set_handle(&th, inode, name,
615 					  buffer, buffer_size, flags);
616 
617 	reiserfs_write_lock(inode->i_sb);
618 	error2 = journal_end(&th);
619 	reiserfs_write_unlock(inode->i_sb);
620 	if (error == 0)
621 		error = error2;
622 
623 	return error;
624 }
625 
626 /*
627  * inode->i_mutex: down
628  */
629 int
630 reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer,
631 		   size_t buffer_size)
632 {
633 	ssize_t err = 0;
634 	struct dentry *dentry;
635 	size_t isize;
636 	size_t file_pos = 0;
637 	size_t buffer_pos = 0;
638 	struct page *page;
639 	__u32 hash = 0;
640 
641 	if (name == NULL)
642 		return -EINVAL;
643 
644 	/*
645 	 * We can't have xattrs attached to v1 items since they don't have
646 	 * generation numbers
647 	 */
648 	if (get_inode_sd_version(inode) == STAT_DATA_V1)
649 		return -EOPNOTSUPP;
650 
651 	dentry = xattr_lookup(inode, name, XATTR_REPLACE);
652 	if (IS_ERR(dentry)) {
653 		err = PTR_ERR(dentry);
654 		goto out;
655 	}
656 
657 	down_read(&REISERFS_I(inode)->i_xattr_sem);
658 
659 	isize = i_size_read(dentry->d_inode);
660 
661 	/* Just return the size needed */
662 	if (buffer == NULL) {
663 		err = isize - sizeof(struct reiserfs_xattr_header);
664 		goto out_unlock;
665 	}
666 
667 	if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
668 		err = -ERANGE;
669 		goto out_unlock;
670 	}
671 
672 	while (file_pos < isize) {
673 		size_t chunk;
674 		char *data;
675 		size_t skip = 0;
676 
677 		if (isize - file_pos > PAGE_CACHE_SIZE)
678 			chunk = PAGE_CACHE_SIZE;
679 		else
680 			chunk = isize - file_pos;
681 
682 		page = reiserfs_get_page(dentry->d_inode, file_pos);
683 		if (IS_ERR(page)) {
684 			err = PTR_ERR(page);
685 			goto out_unlock;
686 		}
687 
688 		lock_page(page);
689 		data = page_address(page);
690 		if (file_pos == 0) {
691 			struct reiserfs_xattr_header *rxh =
692 			    (struct reiserfs_xattr_header *)data;
693 			skip = file_pos = sizeof(struct reiserfs_xattr_header);
694 			chunk -= skip;
695 			/* Magic doesn't match up.. */
696 			if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
697 				unlock_page(page);
698 				reiserfs_put_page(page);
699 				reiserfs_warning(inode->i_sb, "jdm-20001",
700 						 "Invalid magic for xattr (%s) "
701 						 "associated with %k", name,
702 						 INODE_PKEY(inode));
703 				err = -EIO;
704 				goto out_unlock;
705 			}
706 			hash = le32_to_cpu(rxh->h_hash);
707 		}
708 		memcpy(buffer + buffer_pos, data + skip, chunk);
709 		unlock_page(page);
710 		reiserfs_put_page(page);
711 		file_pos += chunk;
712 		buffer_pos += chunk;
713 		skip = 0;
714 	}
715 	err = isize - sizeof(struct reiserfs_xattr_header);
716 
717 	if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
718 	    hash) {
719 		reiserfs_warning(inode->i_sb, "jdm-20002",
720 				 "Invalid hash for xattr (%s) associated "
721 				 "with %k", name, INODE_PKEY(inode));
722 		err = -EIO;
723 	}
724 
725 out_unlock:
726 	up_read(&REISERFS_I(inode)->i_xattr_sem);
727 	dput(dentry);
728 
729 out:
730 	return err;
731 }
732 
733 /*
734  * In order to implement different sets of xattr operations for each xattr
735  * prefix with the generic xattr API, a filesystem should create a
736  * null-terminated array of struct xattr_handler (one for each prefix) and
737  * hang a pointer to it off of the s_xattr field of the superblock.
738  *
739  * The generic_fooxattr() functions will use this list to dispatch xattr
740  * operations to the correct xattr_handler.
741  */
742 #define for_each_xattr_handler(handlers, handler)		\
743 		for ((handler) = *(handlers)++;			\
744 			(handler) != NULL;			\
745 			(handler) = *(handlers)++)
746 
747 /* This is the implementation for the xattr plugin infrastructure */
748 static inline const struct xattr_handler *
749 find_xattr_handler_prefix(const struct xattr_handler **handlers,
750 			   const char *name)
751 {
752 	const struct xattr_handler *xah;
753 
754 	if (!handlers)
755 		return NULL;
756 
757 	for_each_xattr_handler(handlers, xah) {
758 		if (strncmp(xah->prefix, name, strlen(xah->prefix)) == 0)
759 			break;
760 	}
761 
762 	return xah;
763 }
764 
765 
766 /*
767  * Inode operation getxattr()
768  */
769 ssize_t
770 reiserfs_getxattr(struct dentry * dentry, const char *name, void *buffer,
771 		  size_t size)
772 {
773 	const struct xattr_handler *handler;
774 
775 	handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
776 
777 	if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
778 		return -EOPNOTSUPP;
779 
780 	return handler->get(dentry, name, buffer, size, handler->flags);
781 }
782 
783 /*
784  * Inode operation setxattr()
785  *
786  * dentry->d_inode->i_mutex down
787  */
788 int
789 reiserfs_setxattr(struct dentry *dentry, const char *name, const void *value,
790 		  size_t size, int flags)
791 {
792 	const struct xattr_handler *handler;
793 
794 	handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
795 
796 	if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
797 		return -EOPNOTSUPP;
798 
799 	return handler->set(dentry, name, value, size, flags, handler->flags);
800 }
801 
802 /*
803  * Inode operation removexattr()
804  *
805  * dentry->d_inode->i_mutex down
806  */
807 int reiserfs_removexattr(struct dentry *dentry, const char *name)
808 {
809 	const struct xattr_handler *handler;
810 
811 	handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
812 
813 	if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
814 		return -EOPNOTSUPP;
815 
816 	return handler->set(dentry, name, NULL, 0, XATTR_REPLACE, handler->flags);
817 }
818 
819 struct listxattr_buf {
820 	struct dir_context ctx;
821 	size_t size;
822 	size_t pos;
823 	char *buf;
824 	struct dentry *dentry;
825 };
826 
827 static int listxattr_filler(void *buf, const char *name, int namelen,
828 			    loff_t offset, u64 ino, unsigned int d_type)
829 {
830 	struct listxattr_buf *b = (struct listxattr_buf *)buf;
831 	size_t size;
832 
833 	if (name[0] != '.' ||
834 	    (namelen != 1 && (name[1] != '.' || namelen != 2))) {
835 		const struct xattr_handler *handler;
836 
837 		handler = find_xattr_handler_prefix(b->dentry->d_sb->s_xattr,
838 						    name);
839 		if (!handler)	/* Unsupported xattr name */
840 			return 0;
841 		if (b->buf) {
842 			size = handler->list(b->dentry, b->buf + b->pos,
843 					 b->size, name, namelen,
844 					 handler->flags);
845 			if (size > b->size)
846 				return -ERANGE;
847 		} else {
848 			size = handler->list(b->dentry, NULL, 0, name,
849 					     namelen, handler->flags);
850 		}
851 
852 		b->pos += size;
853 	}
854 	return 0;
855 }
856 
857 /*
858  * Inode operation listxattr()
859  *
860  * We totally ignore the generic listxattr here because it would be stupid
861  * not to. Since the xattrs are organized in a directory, we can just
862  * readdir to find them.
863  */
864 ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
865 {
866 	struct dentry *dir;
867 	int err = 0;
868 	struct listxattr_buf buf = {
869 		.ctx.actor = listxattr_filler,
870 		.dentry = dentry,
871 		.buf = buffer,
872 		.size = buffer ? size : 0,
873 	};
874 
875 	if (!dentry->d_inode)
876 		return -EINVAL;
877 
878 	if (!dentry->d_sb->s_xattr ||
879 	    get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
880 		return -EOPNOTSUPP;
881 
882 	dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE);
883 	if (IS_ERR(dir)) {
884 		err = PTR_ERR(dir);
885 		if (err == -ENODATA)
886 			err = 0;  /* Not an error if there aren't any xattrs */
887 		goto out;
888 	}
889 
890 	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
891 	err = reiserfs_readdir_inode(dir->d_inode, &buf.ctx);
892 	mutex_unlock(&dir->d_inode->i_mutex);
893 
894 	if (!err)
895 		err = buf.pos;
896 
897 	dput(dir);
898 out:
899 	return err;
900 }
901 
902 static int create_privroot(struct dentry *dentry)
903 {
904 	int err;
905 	struct inode *inode = dentry->d_parent->d_inode;
906 
907 	WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
908 
909 	err = xattr_mkdir(inode, dentry, 0700);
910 	if (err || !dentry->d_inode) {
911 		reiserfs_warning(dentry->d_sb, "jdm-20006",
912 				 "xattrs/ACLs enabled and couldn't "
913 				 "find/create .reiserfs_priv. "
914 				 "Failing mount.");
915 		return -EOPNOTSUPP;
916 	}
917 
918 	dentry->d_inode->i_flags |= S_PRIVATE;
919 	reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
920 		      "storage.\n", PRIVROOT_NAME);
921 
922 	return 0;
923 }
924 
925 #else
926 int __init reiserfs_xattr_register_handlers(void) { return 0; }
927 void reiserfs_xattr_unregister_handlers(void) {}
928 static int create_privroot(struct dentry *dentry) { return 0; }
929 #endif
930 
931 /* Actual operations that are exported to VFS-land */
932 static const struct xattr_handler *reiserfs_xattr_handlers[] = {
933 #ifdef CONFIG_REISERFS_FS_XATTR
934 	&reiserfs_xattr_user_handler,
935 	&reiserfs_xattr_trusted_handler,
936 #endif
937 #ifdef CONFIG_REISERFS_FS_SECURITY
938 	&reiserfs_xattr_security_handler,
939 #endif
940 #ifdef CONFIG_REISERFS_FS_POSIX_ACL
941 	&posix_acl_access_xattr_handler,
942 	&posix_acl_default_xattr_handler,
943 #endif
944 	NULL
945 };
946 
947 static int xattr_mount_check(struct super_block *s)
948 {
949 	/*
950 	 * We need generation numbers to ensure that the oid mapping is correct
951 	 * v3.5 filesystems don't have them.
952 	 */
953 	if (old_format_only(s)) {
954 		if (reiserfs_xattrs_optional(s)) {
955 			/*
956 			 * Old format filesystem, but optional xattrs have
957 			 * been enabled. Error out.
958 			 */
959 			reiserfs_warning(s, "jdm-2005",
960 					 "xattrs/ACLs not supported "
961 					 "on pre-v3.6 format filesystems. "
962 					 "Failing mount.");
963 			return -EOPNOTSUPP;
964 		}
965 	}
966 
967 	return 0;
968 }
969 
970 int reiserfs_permission(struct inode *inode, int mask)
971 {
972 	/*
973 	 * We don't do permission checks on the internal objects.
974 	 * Permissions are determined by the "owning" object.
975 	 */
976 	if (IS_PRIVATE(inode))
977 		return 0;
978 
979 	return generic_permission(inode, mask);
980 }
981 
982 static int xattr_hide_revalidate(struct dentry *dentry, unsigned int flags)
983 {
984 	return -EPERM;
985 }
986 
987 static const struct dentry_operations xattr_lookup_poison_ops = {
988 	.d_revalidate = xattr_hide_revalidate,
989 };
990 
991 int reiserfs_lookup_privroot(struct super_block *s)
992 {
993 	struct dentry *dentry;
994 	int err = 0;
995 
996 	/* If we don't have the privroot located yet - go find it */
997 	mutex_lock(&s->s_root->d_inode->i_mutex);
998 	dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
999 				strlen(PRIVROOT_NAME));
1000 	if (!IS_ERR(dentry)) {
1001 		REISERFS_SB(s)->priv_root = dentry;
1002 		d_set_d_op(dentry, &xattr_lookup_poison_ops);
1003 		if (dentry->d_inode)
1004 			dentry->d_inode->i_flags |= S_PRIVATE;
1005 	} else
1006 		err = PTR_ERR(dentry);
1007 	mutex_unlock(&s->s_root->d_inode->i_mutex);
1008 
1009 	return err;
1010 }
1011 
1012 /*
1013  * We need to take a copy of the mount flags since things like
1014  * MS_RDONLY don't get set until *after* we're called.
1015  * mount_flags != mount_options
1016  */
1017 int reiserfs_xattr_init(struct super_block *s, int mount_flags)
1018 {
1019 	int err = 0;
1020 	struct dentry *privroot = REISERFS_SB(s)->priv_root;
1021 
1022 	err = xattr_mount_check(s);
1023 	if (err)
1024 		goto error;
1025 
1026 	if (!privroot->d_inode && !(mount_flags & MS_RDONLY)) {
1027 		mutex_lock(&s->s_root->d_inode->i_mutex);
1028 		err = create_privroot(REISERFS_SB(s)->priv_root);
1029 		mutex_unlock(&s->s_root->d_inode->i_mutex);
1030 	}
1031 
1032 	if (privroot->d_inode) {
1033 		s->s_xattr = reiserfs_xattr_handlers;
1034 		mutex_lock(&privroot->d_inode->i_mutex);
1035 		if (!REISERFS_SB(s)->xattr_root) {
1036 			struct dentry *dentry;
1037 
1038 			dentry = lookup_one_len(XAROOT_NAME, privroot,
1039 						strlen(XAROOT_NAME));
1040 			if (!IS_ERR(dentry))
1041 				REISERFS_SB(s)->xattr_root = dentry;
1042 			else
1043 				err = PTR_ERR(dentry);
1044 		}
1045 		mutex_unlock(&privroot->d_inode->i_mutex);
1046 	}
1047 
1048 error:
1049 	if (err) {
1050 		clear_bit(REISERFS_XATTRS_USER, &REISERFS_SB(s)->s_mount_opt);
1051 		clear_bit(REISERFS_POSIXACL, &REISERFS_SB(s)->s_mount_opt);
1052 	}
1053 
1054 	/* The super_block MS_POSIXACL must mirror the (no)acl mount option. */
1055 	if (reiserfs_posixacl(s))
1056 		s->s_flags |= MS_POSIXACL;
1057 	else
1058 		s->s_flags &= ~MS_POSIXACL;
1059 
1060 	return err;
1061 }
1062