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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext2/xattr.c
4 *
5 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>
6 *
7 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
8 * Extended attributes for symlinks and special files added per
9 * suggestion of Luka Renko <luka.renko@hermes.si>.
10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
11 * Red Hat Inc.
12 *
13 */
14
15/*
16 * Extended attributes are stored on disk blocks allocated outside of
17 * any inode. The i_file_acl field is then made to point to this allocated
18 * block. If all extended attributes of an inode are identical, these
19 * inodes may share the same extended attribute block. Such situations
20 * are automatically detected by keeping a cache of recent attribute block
21 * numbers and hashes over the block's contents in memory.
22 *
23 *
24 * Extended attribute block layout:
25 *
26 * +------------------+
27 * | header |
28 * | entry 1 | |
29 * | entry 2 | | growing downwards
30 * | entry 3 | v
31 * | four null bytes |
32 * | . . . |
33 * | value 1 | ^
34 * | value 3 | | growing upwards
35 * | value 2 | |
36 * +------------------+
37 *
38 * The block header is followed by multiple entry descriptors. These entry
39 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD
40 * byte boundaries. The entry descriptors are sorted by attribute name,
41 * so that two extended attribute blocks can be compared efficiently.
42 *
43 * Attribute values are aligned to the end of the block, stored in
44 * no specific order. They are also padded to EXT2_XATTR_PAD byte
45 * boundaries. No additional gaps are left between them.
46 *
47 * Locking strategy
48 * ----------------
49 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem.
50 * EA blocks are only changed if they are exclusive to an inode, so
51 * holding xattr_sem also means that nothing but the EA block's reference
52 * count will change. Multiple writers to an EA block are synchronized
53 * by the bh lock. No more than a single bh lock is held at any time
54 * to avoid deadlocks.
55 */
56
57#include <linux/buffer_head.h>
58#include <linux/init.h>
59#include <linux/printk.h>
60#include <linux/slab.h>
61#include <linux/mbcache.h>
62#include <linux/quotaops.h>
63#include <linux/rwsem.h>
64#include <linux/security.h>
65#include "ext2.h"
66#include "xattr.h"
67#include "acl.h"
68
69#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
70#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
71#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
72#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
73
74#ifdef EXT2_XATTR_DEBUG
75# define ea_idebug(inode, f...) do { \
76 printk(KERN_DEBUG "inode %s:%ld: ", \
77 inode->i_sb->s_id, inode->i_ino); \
78 printk(f); \
79 printk("\n"); \
80 } while (0)
81# define ea_bdebug(bh, f...) do { \
82 printk(KERN_DEBUG "block %pg:%lu: ", \
83 bh->b_bdev, (unsigned long) bh->b_blocknr); \
84 printk(f); \
85 printk("\n"); \
86 } while (0)
87#else
88# define ea_idebug(inode, f...) no_printk(f)
89# define ea_bdebug(bh, f...) no_printk(f)
90#endif
91
92static int ext2_xattr_set2(struct inode *, struct buffer_head *,
93 struct ext2_xattr_header *);
94
95static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
96static struct buffer_head *ext2_xattr_cache_find(struct inode *,
97 struct ext2_xattr_header *);
98static void ext2_xattr_rehash(struct ext2_xattr_header *,
99 struct ext2_xattr_entry *);
100
101static const struct xattr_handler * const ext2_xattr_handler_map[] = {
102 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
103#ifdef CONFIG_EXT2_FS_POSIX_ACL
104 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &nop_posix_acl_access,
105 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &nop_posix_acl_default,
106#endif
107 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
108#ifdef CONFIG_EXT2_FS_SECURITY
109 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
110#endif
111};
112
113const struct xattr_handler * const ext2_xattr_handlers[] = {
114 &ext2_xattr_user_handler,
115 &ext2_xattr_trusted_handler,
116#ifdef CONFIG_EXT2_FS_SECURITY
117 &ext2_xattr_security_handler,
118#endif
119 NULL
120};
121
122#define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache)
123
124static inline const char *ext2_xattr_prefix(int name_index,
125 struct dentry *dentry)
126{
127 const struct xattr_handler *handler = NULL;
128
129 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
130 handler = ext2_xattr_handler_map[name_index];
131
132 if (!xattr_handler_can_list(handler, dentry))
133 return NULL;
134
135 return xattr_prefix(handler);
136}
137
138static bool
139ext2_xattr_header_valid(struct ext2_xattr_header *header)
140{
141 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
142 header->h_blocks != cpu_to_le32(1))
143 return false;
144
145 return true;
146}
147
148static bool
149ext2_xattr_entry_valid(struct ext2_xattr_entry *entry,
150 char *end, size_t end_offs)
151{
152 struct ext2_xattr_entry *next;
153 size_t size;
154
155 next = EXT2_XATTR_NEXT(entry);
156 if ((char *)next >= end)
157 return false;
158
159 if (entry->e_value_block != 0)
160 return false;
161
162 size = le32_to_cpu(entry->e_value_size);
163 if (size > end_offs ||
164 le16_to_cpu(entry->e_value_offs) + size > end_offs)
165 return false;
166
167 return true;
168}
169
170static int
171ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name,
172 struct ext2_xattr_entry *entry)
173{
174 int cmp;
175
176 cmp = name_index - entry->e_name_index;
177 if (!cmp)
178 cmp = name_len - entry->e_name_len;
179 if (!cmp)
180 cmp = memcmp(name, entry->e_name, name_len);
181
182 return cmp;
183}
184
185/*
186 * ext2_xattr_get()
187 *
188 * Copy an extended attribute into the buffer
189 * provided, or compute the buffer size required.
190 * Buffer is NULL to compute the size of the buffer required.
191 *
192 * Returns a negative error number on failure, or the number of bytes
193 * used / required on success.
194 */
195int
196ext2_xattr_get(struct inode *inode, int name_index, const char *name,
197 void *buffer, size_t buffer_size)
198{
199 struct buffer_head *bh = NULL;
200 struct ext2_xattr_entry *entry;
201 size_t name_len, size;
202 char *end;
203 int error, not_found;
204 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
205
206 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
207 name_index, name, buffer, (long)buffer_size);
208
209 if (name == NULL)
210 return -EINVAL;
211 name_len = strlen(name);
212 if (name_len > 255)
213 return -ERANGE;
214
215 down_read(&EXT2_I(inode)->xattr_sem);
216 error = -ENODATA;
217 if (!EXT2_I(inode)->i_file_acl)
218 goto cleanup;
219 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
220 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
221 error = -EIO;
222 if (!bh)
223 goto cleanup;
224 ea_bdebug(bh, "b_count=%d, refcount=%d",
225 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
226 end = bh->b_data + bh->b_size;
227 if (!ext2_xattr_header_valid(HDR(bh))) {
228bad_block:
229 ext2_error(inode->i_sb, "ext2_xattr_get",
230 "inode %ld: bad block %d", inode->i_ino,
231 EXT2_I(inode)->i_file_acl);
232 error = -EIO;
233 goto cleanup;
234 }
235
236 /* find named attribute */
237 entry = FIRST_ENTRY(bh);
238 while (!IS_LAST_ENTRY(entry)) {
239 if (!ext2_xattr_entry_valid(entry, end,
240 inode->i_sb->s_blocksize))
241 goto bad_block;
242
243 not_found = ext2_xattr_cmp_entry(name_index, name_len, name,
244 entry);
245 if (!not_found)
246 goto found;
247 if (not_found < 0)
248 break;
249
250 entry = EXT2_XATTR_NEXT(entry);
251 }
252 if (ext2_xattr_cache_insert(ea_block_cache, bh))
253 ea_idebug(inode, "cache insert failed");
254 error = -ENODATA;
255 goto cleanup;
256found:
257 size = le32_to_cpu(entry->e_value_size);
258 if (ext2_xattr_cache_insert(ea_block_cache, bh))
259 ea_idebug(inode, "cache insert failed");
260 if (buffer) {
261 error = -ERANGE;
262 if (size > buffer_size)
263 goto cleanup;
264 /* return value of attribute */
265 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
266 size);
267 }
268 error = size;
269
270cleanup:
271 brelse(bh);
272 up_read(&EXT2_I(inode)->xattr_sem);
273
274 return error;
275}
276
277/*
278 * ext2_xattr_list()
279 *
280 * Copy a list of attribute names into the buffer
281 * provided, or compute the buffer size required.
282 * Buffer is NULL to compute the size of the buffer required.
283 *
284 * Returns a negative error number on failure, or the number of bytes
285 * used / required on success.
286 */
287static int
288ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
289{
290 struct inode *inode = d_inode(dentry);
291 struct buffer_head *bh = NULL;
292 struct ext2_xattr_entry *entry;
293 char *end;
294 size_t rest = buffer_size;
295 int error;
296 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
297
298 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
299 buffer, (long)buffer_size);
300
301 down_read(&EXT2_I(inode)->xattr_sem);
302 error = 0;
303 if (!EXT2_I(inode)->i_file_acl)
304 goto cleanup;
305 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
306 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
307 error = -EIO;
308 if (!bh)
309 goto cleanup;
310 ea_bdebug(bh, "b_count=%d, refcount=%d",
311 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
312 end = bh->b_data + bh->b_size;
313 if (!ext2_xattr_header_valid(HDR(bh))) {
314bad_block:
315 ext2_error(inode->i_sb, "ext2_xattr_list",
316 "inode %ld: bad block %d", inode->i_ino,
317 EXT2_I(inode)->i_file_acl);
318 error = -EIO;
319 goto cleanup;
320 }
321
322 /* check the on-disk data structure */
323 entry = FIRST_ENTRY(bh);
324 while (!IS_LAST_ENTRY(entry)) {
325 if (!ext2_xattr_entry_valid(entry, end,
326 inode->i_sb->s_blocksize))
327 goto bad_block;
328 entry = EXT2_XATTR_NEXT(entry);
329 }
330 if (ext2_xattr_cache_insert(ea_block_cache, bh))
331 ea_idebug(inode, "cache insert failed");
332
333 /* list the attribute names */
334 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
335 entry = EXT2_XATTR_NEXT(entry)) {
336 const char *prefix;
337
338 prefix = ext2_xattr_prefix(entry->e_name_index, dentry);
339 if (prefix) {
340 size_t prefix_len = strlen(prefix);
341 size_t size = prefix_len + entry->e_name_len + 1;
342
343 if (buffer) {
344 if (size > rest) {
345 error = -ERANGE;
346 goto cleanup;
347 }
348 memcpy(buffer, prefix, prefix_len);
349 buffer += prefix_len;
350 memcpy(buffer, entry->e_name, entry->e_name_len);
351 buffer += entry->e_name_len;
352 *buffer++ = 0;
353 }
354 rest -= size;
355 }
356 }
357 error = buffer_size - rest; /* total size */
358
359cleanup:
360 brelse(bh);
361 up_read(&EXT2_I(inode)->xattr_sem);
362
363 return error;
364}
365
366/*
367 * Inode operation listxattr()
368 *
369 * d_inode(dentry)->i_mutex: don't care
370 */
371ssize_t
372ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
373{
374 return ext2_xattr_list(dentry, buffer, size);
375}
376
377/*
378 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
379 * not set, set it.
380 */
381static void ext2_xattr_update_super_block(struct super_block *sb)
382{
383 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
384 return;
385
386 spin_lock(&EXT2_SB(sb)->s_lock);
387 ext2_update_dynamic_rev(sb);
388 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
389 spin_unlock(&EXT2_SB(sb)->s_lock);
390 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
391}
392
393/*
394 * ext2_xattr_set()
395 *
396 * Create, replace or remove an extended attribute for this inode. Value
397 * is NULL to remove an existing extended attribute, and non-NULL to
398 * either replace an existing extended attribute, or create a new extended
399 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
400 * specify that an extended attribute must exist and must not exist
401 * previous to the call, respectively.
402 *
403 * Returns 0, or a negative error number on failure.
404 */
405int
406ext2_xattr_set(struct inode *inode, int name_index, const char *name,
407 const void *value, size_t value_len, int flags)
408{
409 struct super_block *sb = inode->i_sb;
410 struct buffer_head *bh = NULL;
411 struct ext2_xattr_header *header = NULL;
412 struct ext2_xattr_entry *here = NULL, *last = NULL;
413 size_t name_len, free, min_offs = sb->s_blocksize;
414 int not_found = 1, error;
415 char *end;
416
417 /*
418 * header -- Points either into bh, or to a temporarily
419 * allocated buffer.
420 * here -- The named entry found, or the place for inserting, within
421 * the block pointed to by header.
422 * last -- Points right after the last named entry within the block
423 * pointed to by header.
424 * min_offs -- The offset of the first value (values are aligned
425 * towards the end of the block).
426 * end -- Points right after the block pointed to by header.
427 */
428
429 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
430 name_index, name, value, (long)value_len);
431
432 if (value == NULL)
433 value_len = 0;
434 if (name == NULL)
435 return -EINVAL;
436 name_len = strlen(name);
437 if (name_len > 255 || value_len > sb->s_blocksize)
438 return -ERANGE;
439 error = dquot_initialize(inode);
440 if (error)
441 return error;
442 down_write(&EXT2_I(inode)->xattr_sem);
443 if (EXT2_I(inode)->i_file_acl) {
444 /* The inode already has an extended attribute block. */
445 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
446 error = -EIO;
447 if (!bh)
448 goto cleanup;
449 ea_bdebug(bh, "b_count=%d, refcount=%d",
450 atomic_read(&(bh->b_count)),
451 le32_to_cpu(HDR(bh)->h_refcount));
452 header = HDR(bh);
453 end = bh->b_data + bh->b_size;
454 if (!ext2_xattr_header_valid(header)) {
455bad_block:
456 ext2_error(sb, "ext2_xattr_set",
457 "inode %ld: bad block %d", inode->i_ino,
458 EXT2_I(inode)->i_file_acl);
459 error = -EIO;
460 goto cleanup;
461 }
462 /*
463 * Find the named attribute. If not found, 'here' will point
464 * to entry where the new attribute should be inserted to
465 * maintain sorting.
466 */
467 last = FIRST_ENTRY(bh);
468 while (!IS_LAST_ENTRY(last)) {
469 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize))
470 goto bad_block;
471 if (last->e_value_size) {
472 size_t offs = le16_to_cpu(last->e_value_offs);
473 if (offs < min_offs)
474 min_offs = offs;
475 }
476 if (not_found > 0) {
477 not_found = ext2_xattr_cmp_entry(name_index,
478 name_len,
479 name, last);
480 if (not_found <= 0)
481 here = last;
482 }
483 last = EXT2_XATTR_NEXT(last);
484 }
485 if (not_found > 0)
486 here = last;
487
488 /* Check whether we have enough space left. */
489 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
490 } else {
491 /* We will use a new extended attribute block. */
492 free = sb->s_blocksize -
493 sizeof(struct ext2_xattr_header) - sizeof(__u32);
494 }
495
496 if (not_found) {
497 /* Request to remove a nonexistent attribute? */
498 error = -ENODATA;
499 if (flags & XATTR_REPLACE)
500 goto cleanup;
501 error = 0;
502 if (value == NULL)
503 goto cleanup;
504 } else {
505 /* Request to create an existing attribute? */
506 error = -EEXIST;
507 if (flags & XATTR_CREATE)
508 goto cleanup;
509 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size));
510 free += EXT2_XATTR_LEN(name_len);
511 }
512 error = -ENOSPC;
513 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
514 goto cleanup;
515
516 /* Here we know that we can set the new attribute. */
517
518 if (header) {
519 int offset;
520
521 lock_buffer(bh);
522 if (header->h_refcount == cpu_to_le32(1)) {
523 __u32 hash = le32_to_cpu(header->h_hash);
524 struct mb_cache_entry *oe;
525
526 oe = mb_cache_entry_delete_or_get(EA_BLOCK_CACHE(inode),
527 hash, bh->b_blocknr);
528 if (!oe) {
529 ea_bdebug(bh, "modifying in-place");
530 goto update_block;
531 }
532 /*
533 * Someone is trying to reuse the block, leave it alone
534 */
535 mb_cache_entry_put(EA_BLOCK_CACHE(inode), oe);
536 }
537 unlock_buffer(bh);
538 ea_bdebug(bh, "cloning");
539 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL);
540 error = -ENOMEM;
541 if (header == NULL)
542 goto cleanup;
543 header->h_refcount = cpu_to_le32(1);
544
545 offset = (char *)here - bh->b_data;
546 here = ENTRY((char *)header + offset);
547 offset = (char *)last - bh->b_data;
548 last = ENTRY((char *)header + offset);
549 } else {
550 /* Allocate a buffer where we construct the new block. */
551 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
552 error = -ENOMEM;
553 if (header == NULL)
554 goto cleanup;
555 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
556 header->h_blocks = header->h_refcount = cpu_to_le32(1);
557 last = here = ENTRY(header+1);
558 }
559
560update_block:
561 /* Iff we are modifying the block in-place, bh is locked here. */
562
563 if (not_found) {
564 /* Insert the new name. */
565 size_t size = EXT2_XATTR_LEN(name_len);
566 size_t rest = (char *)last - (char *)here;
567 memmove((char *)here + size, here, rest);
568 memset(here, 0, size);
569 here->e_name_index = name_index;
570 here->e_name_len = name_len;
571 memcpy(here->e_name, name, name_len);
572 } else {
573 if (here->e_value_size) {
574 char *first_val = (char *)header + min_offs;
575 size_t offs = le16_to_cpu(here->e_value_offs);
576 char *val = (char *)header + offs;
577 size_t size = EXT2_XATTR_SIZE(
578 le32_to_cpu(here->e_value_size));
579
580 if (size == EXT2_XATTR_SIZE(value_len)) {
581 /* The old and the new value have the same
582 size. Just replace. */
583 here->e_value_size = cpu_to_le32(value_len);
584 memset(val + size - EXT2_XATTR_PAD, 0,
585 EXT2_XATTR_PAD); /* Clear pad bytes. */
586 memcpy(val, value, value_len);
587 goto skip_replace;
588 }
589
590 /* Remove the old value. */
591 memmove(first_val + size, first_val, val - first_val);
592 memset(first_val, 0, size);
593 min_offs += size;
594
595 /* Adjust all value offsets. */
596 last = ENTRY(header+1);
597 while (!IS_LAST_ENTRY(last)) {
598 size_t o = le16_to_cpu(last->e_value_offs);
599 if (o < offs)
600 last->e_value_offs =
601 cpu_to_le16(o + size);
602 last = EXT2_XATTR_NEXT(last);
603 }
604
605 here->e_value_offs = 0;
606 }
607 if (value == NULL) {
608 /* Remove the old name. */
609 size_t size = EXT2_XATTR_LEN(name_len);
610 last = ENTRY((char *)last - size);
611 memmove(here, (char*)here + size,
612 (char*)last - (char*)here);
613 memset(last, 0, size);
614 }
615 }
616
617 if (value != NULL) {
618 /* Insert the new value. */
619 here->e_value_size = cpu_to_le32(value_len);
620 if (value_len) {
621 size_t size = EXT2_XATTR_SIZE(value_len);
622 char *val = (char *)header + min_offs - size;
623 here->e_value_offs =
624 cpu_to_le16((char *)val - (char *)header);
625 memset(val + size - EXT2_XATTR_PAD, 0,
626 EXT2_XATTR_PAD); /* Clear the pad bytes. */
627 memcpy(val, value, value_len);
628 }
629 }
630
631skip_replace:
632 if (IS_LAST_ENTRY(ENTRY(header+1))) {
633 /* This block is now empty. */
634 if (bh && header == HDR(bh))
635 unlock_buffer(bh); /* we were modifying in-place. */
636 error = ext2_xattr_set2(inode, bh, NULL);
637 } else {
638 ext2_xattr_rehash(header, here);
639 if (bh && header == HDR(bh))
640 unlock_buffer(bh); /* we were modifying in-place. */
641 error = ext2_xattr_set2(inode, bh, header);
642 }
643
644cleanup:
645 if (!(bh && header == HDR(bh)))
646 kfree(header);
647 brelse(bh);
648 up_write(&EXT2_I(inode)->xattr_sem);
649
650 return error;
651}
652
653static void ext2_xattr_release_block(struct inode *inode,
654 struct buffer_head *bh)
655{
656 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
657
658retry_ref:
659 lock_buffer(bh);
660 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
661 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
662 struct mb_cache_entry *oe;
663
664 /*
665 * This must happen under buffer lock to properly
666 * serialize with ext2_xattr_set() reusing the block.
667 */
668 oe = mb_cache_entry_delete_or_get(ea_block_cache, hash,
669 bh->b_blocknr);
670 if (oe) {
671 /*
672 * Someone is trying to reuse the block. Wait
673 * and retry.
674 */
675 unlock_buffer(bh);
676 mb_cache_entry_wait_unused(oe);
677 mb_cache_entry_put(ea_block_cache, oe);
678 goto retry_ref;
679 }
680
681 /* Free the old block. */
682 ea_bdebug(bh, "freeing");
683 ext2_free_blocks(inode, bh->b_blocknr, 1);
684 /* We let our caller release bh, so we
685 * need to duplicate the buffer before. */
686 get_bh(bh);
687 bforget(bh);
688 unlock_buffer(bh);
689 } else {
690 /* Decrement the refcount only. */
691 le32_add_cpu(&HDR(bh)->h_refcount, -1);
692 dquot_free_block(inode, 1);
693 mark_buffer_dirty(bh);
694 unlock_buffer(bh);
695 ea_bdebug(bh, "refcount now=%d",
696 le32_to_cpu(HDR(bh)->h_refcount));
697 if (IS_SYNC(inode))
698 sync_dirty_buffer(bh);
699 }
700}
701
702/*
703 * Second half of ext2_xattr_set(): Update the file system.
704 */
705static int
706ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
707 struct ext2_xattr_header *header)
708{
709 struct super_block *sb = inode->i_sb;
710 struct buffer_head *new_bh = NULL;
711 int error;
712 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
713
714 if (header) {
715 new_bh = ext2_xattr_cache_find(inode, header);
716 if (new_bh) {
717 /* We found an identical block in the cache. */
718 if (new_bh == old_bh) {
719 ea_bdebug(new_bh, "keeping this block");
720 } else {
721 /* The old block is released after updating
722 the inode. */
723 ea_bdebug(new_bh, "reusing block");
724
725 error = dquot_alloc_block(inode, 1);
726 if (error) {
727 unlock_buffer(new_bh);
728 goto cleanup;
729 }
730 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
731 ea_bdebug(new_bh, "refcount now=%d",
732 le32_to_cpu(HDR(new_bh)->h_refcount));
733 }
734 unlock_buffer(new_bh);
735 } else if (old_bh && header == HDR(old_bh)) {
736 /* Keep this block. No need to lock the block as we
737 don't need to change the reference count. */
738 new_bh = old_bh;
739 get_bh(new_bh);
740 ext2_xattr_cache_insert(ea_block_cache, new_bh);
741 } else {
742 /* We need to allocate a new block */
743 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
744 EXT2_I(inode)->i_block_group);
745 unsigned long count = 1;
746 ext2_fsblk_t block = ext2_new_blocks(inode, goal,
747 &count, &error,
748 EXT2_ALLOC_NORESERVE);
749 if (error)
750 goto cleanup;
751 ea_idebug(inode, "creating block %lu", block);
752
753 new_bh = sb_getblk(sb, block);
754 if (unlikely(!new_bh)) {
755 ext2_free_blocks(inode, block, 1);
756 mark_inode_dirty(inode);
757 error = -ENOMEM;
758 goto cleanup;
759 }
760 lock_buffer(new_bh);
761 memcpy(new_bh->b_data, header, new_bh->b_size);
762 set_buffer_uptodate(new_bh);
763 unlock_buffer(new_bh);
764 ext2_xattr_cache_insert(ea_block_cache, new_bh);
765
766 ext2_xattr_update_super_block(sb);
767 }
768 mark_buffer_dirty(new_bh);
769 if (IS_SYNC(inode)) {
770 sync_dirty_buffer(new_bh);
771 error = -EIO;
772 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
773 goto cleanup;
774 }
775 }
776
777 /* Update the inode. */
778 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
779 inode_set_ctime_current(inode);
780 if (IS_SYNC(inode)) {
781 error = sync_inode_metadata(inode, 1);
782 /* In case sync failed due to ENOSPC the inode was actually
783 * written (only some dirty data were not) so we just proceed
784 * as if nothing happened and cleanup the unused block */
785 if (error && error != -ENOSPC) {
786 if (new_bh && new_bh != old_bh) {
787 dquot_free_block_nodirty(inode, 1);
788 mark_inode_dirty(inode);
789 }
790 goto cleanup;
791 }
792 } else
793 mark_inode_dirty(inode);
794
795 error = 0;
796 if (old_bh && old_bh != new_bh) {
797 /*
798 * If there was an old block and we are no longer using it,
799 * release the old block.
800 */
801 ext2_xattr_release_block(inode, old_bh);
802 }
803
804cleanup:
805 brelse(new_bh);
806
807 return error;
808}
809
810/*
811 * ext2_xattr_delete_inode()
812 *
813 * Free extended attribute resources associated with this inode. This
814 * is called immediately before an inode is freed.
815 */
816void
817ext2_xattr_delete_inode(struct inode *inode)
818{
819 struct buffer_head *bh = NULL;
820 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
821
822 /*
823 * We are the only ones holding inode reference. The xattr_sem should
824 * better be unlocked! We could as well just not acquire xattr_sem at
825 * all but this makes the code more futureproof. OTOH we need trylock
826 * here to avoid false-positive warning from lockdep about reclaim
827 * circular dependency.
828 */
829 if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem)))
830 return;
831 if (!EXT2_I(inode)->i_file_acl)
832 goto cleanup;
833
834 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) {
835 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
836 "inode %ld: xattr block %d is out of data blocks range",
837 inode->i_ino, EXT2_I(inode)->i_file_acl);
838 goto cleanup;
839 }
840
841 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
842 if (!bh) {
843 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
844 "inode %ld: block %d read error", inode->i_ino,
845 EXT2_I(inode)->i_file_acl);
846 goto cleanup;
847 }
848 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
849 if (!ext2_xattr_header_valid(HDR(bh))) {
850 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
851 "inode %ld: bad block %d", inode->i_ino,
852 EXT2_I(inode)->i_file_acl);
853 goto cleanup;
854 }
855 ext2_xattr_release_block(inode, bh);
856 EXT2_I(inode)->i_file_acl = 0;
857
858cleanup:
859 brelse(bh);
860 up_write(&EXT2_I(inode)->xattr_sem);
861}
862
863/*
864 * ext2_xattr_cache_insert()
865 *
866 * Create a new entry in the extended attribute cache, and insert
867 * it unless such an entry is already in the cache.
868 *
869 * Returns 0, or a negative error number on failure.
870 */
871static int
872ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)
873{
874 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
875 int error;
876
877 error = mb_cache_entry_create(cache, GFP_KERNEL, hash, bh->b_blocknr,
878 true);
879 if (error) {
880 if (error == -EBUSY) {
881 ea_bdebug(bh, "already in cache");
882 error = 0;
883 }
884 } else
885 ea_bdebug(bh, "inserting [%x]", (int)hash);
886 return error;
887}
888
889/*
890 * ext2_xattr_cmp()
891 *
892 * Compare two extended attribute blocks for equality.
893 *
894 * Returns 0 if the blocks are equal, 1 if they differ, and
895 * a negative error number on errors.
896 */
897static int
898ext2_xattr_cmp(struct ext2_xattr_header *header1,
899 struct ext2_xattr_header *header2)
900{
901 struct ext2_xattr_entry *entry1, *entry2;
902
903 entry1 = ENTRY(header1+1);
904 entry2 = ENTRY(header2+1);
905 while (!IS_LAST_ENTRY(entry1)) {
906 if (IS_LAST_ENTRY(entry2))
907 return 1;
908 if (entry1->e_hash != entry2->e_hash ||
909 entry1->e_name_index != entry2->e_name_index ||
910 entry1->e_name_len != entry2->e_name_len ||
911 entry1->e_value_size != entry2->e_value_size ||
912 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
913 return 1;
914 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
915 return -EIO;
916 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
917 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
918 le32_to_cpu(entry1->e_value_size)))
919 return 1;
920
921 entry1 = EXT2_XATTR_NEXT(entry1);
922 entry2 = EXT2_XATTR_NEXT(entry2);
923 }
924 if (!IS_LAST_ENTRY(entry2))
925 return 1;
926 return 0;
927}
928
929/*
930 * ext2_xattr_cache_find()
931 *
932 * Find an identical extended attribute block.
933 *
934 * Returns a locked buffer head to the block found, or NULL if such
935 * a block was not found or an error occurred.
936 */
937static struct buffer_head *
938ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
939{
940 __u32 hash = le32_to_cpu(header->h_hash);
941 struct mb_cache_entry *ce;
942 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
943
944 if (!header->h_hash)
945 return NULL; /* never share */
946 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
947
948 ce = mb_cache_entry_find_first(ea_block_cache, hash);
949 while (ce) {
950 struct buffer_head *bh;
951
952 bh = sb_bread(inode->i_sb, ce->e_value);
953 if (!bh) {
954 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
955 "inode %ld: block %ld read error",
956 inode->i_ino, (unsigned long) ce->e_value);
957 } else {
958 lock_buffer(bh);
959 if (le32_to_cpu(HDR(bh)->h_refcount) >
960 EXT2_XATTR_REFCOUNT_MAX) {
961 ea_idebug(inode, "block %ld refcount %d>%d",
962 (unsigned long) ce->e_value,
963 le32_to_cpu(HDR(bh)->h_refcount),
964 EXT2_XATTR_REFCOUNT_MAX);
965 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
966 ea_bdebug(bh, "b_count=%d",
967 atomic_read(&(bh->b_count)));
968 mb_cache_entry_touch(ea_block_cache, ce);
969 mb_cache_entry_put(ea_block_cache, ce);
970 return bh;
971 }
972 unlock_buffer(bh);
973 brelse(bh);
974 }
975 ce = mb_cache_entry_find_next(ea_block_cache, ce);
976 }
977 return NULL;
978}
979
980#define NAME_HASH_SHIFT 5
981#define VALUE_HASH_SHIFT 16
982
983/*
984 * ext2_xattr_hash_entry()
985 *
986 * Compute the hash of an extended attribute.
987 */
988static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
989 struct ext2_xattr_entry *entry)
990{
991 __u32 hash = 0;
992 char *name = entry->e_name;
993 int n;
994
995 for (n=0; n < entry->e_name_len; n++) {
996 hash = (hash << NAME_HASH_SHIFT) ^
997 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
998 *name++;
999 }
1000
1001 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1002 __le32 *value = (__le32 *)((char *)header +
1003 le16_to_cpu(entry->e_value_offs));
1004 for (n = (le32_to_cpu(entry->e_value_size) +
1005 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
1006 hash = (hash << VALUE_HASH_SHIFT) ^
1007 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1008 le32_to_cpu(*value++);
1009 }
1010 }
1011 entry->e_hash = cpu_to_le32(hash);
1012}
1013
1014#undef NAME_HASH_SHIFT
1015#undef VALUE_HASH_SHIFT
1016
1017#define BLOCK_HASH_SHIFT 16
1018
1019/*
1020 * ext2_xattr_rehash()
1021 *
1022 * Re-compute the extended attribute hash value after an entry has changed.
1023 */
1024static void ext2_xattr_rehash(struct ext2_xattr_header *header,
1025 struct ext2_xattr_entry *entry)
1026{
1027 struct ext2_xattr_entry *here;
1028 __u32 hash = 0;
1029
1030 ext2_xattr_hash_entry(header, entry);
1031 here = ENTRY(header+1);
1032 while (!IS_LAST_ENTRY(here)) {
1033 if (!here->e_hash) {
1034 /* Block is not shared if an entry's hash value == 0 */
1035 hash = 0;
1036 break;
1037 }
1038 hash = (hash << BLOCK_HASH_SHIFT) ^
1039 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1040 le32_to_cpu(here->e_hash);
1041 here = EXT2_XATTR_NEXT(here);
1042 }
1043 header->h_hash = cpu_to_le32(hash);
1044}
1045
1046#undef BLOCK_HASH_SHIFT
1047
1048#define HASH_BUCKET_BITS 10
1049
1050struct mb_cache *ext2_xattr_create_cache(void)
1051{
1052 return mb_cache_create(HASH_BUCKET_BITS);
1053}
1054
1055void ext2_xattr_destroy_cache(struct mb_cache *cache)
1056{
1057 if (cache)
1058 mb_cache_destroy(cache);
1059}
1/*
2 * linux/fs/ext2/xattr.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>
5 *
6 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
7 * Extended attributes for symlinks and special files added per
8 * suggestion of Luka Renko <luka.renko@hermes.si>.
9 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
10 * Red Hat Inc.
11 *
12 */
13
14/*
15 * Extended attributes are stored on disk blocks allocated outside of
16 * any inode. The i_file_acl field is then made to point to this allocated
17 * block. If all extended attributes of an inode are identical, these
18 * inodes may share the same extended attribute block. Such situations
19 * are automatically detected by keeping a cache of recent attribute block
20 * numbers and hashes over the block's contents in memory.
21 *
22 *
23 * Extended attribute block layout:
24 *
25 * +------------------+
26 * | header |
27 * | entry 1 | |
28 * | entry 2 | | growing downwards
29 * | entry 3 | v
30 * | four null bytes |
31 * | . . . |
32 * | value 1 | ^
33 * | value 3 | | growing upwards
34 * | value 2 | |
35 * +------------------+
36 *
37 * The block header is followed by multiple entry descriptors. These entry
38 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD
39 * byte boundaries. The entry descriptors are sorted by attribute name,
40 * so that two extended attribute blocks can be compared efficiently.
41 *
42 * Attribute values are aligned to the end of the block, stored in
43 * no specific order. They are also padded to EXT2_XATTR_PAD byte
44 * boundaries. No additional gaps are left between them.
45 *
46 * Locking strategy
47 * ----------------
48 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem.
49 * EA blocks are only changed if they are exclusive to an inode, so
50 * holding xattr_sem also means that nothing but the EA block's reference
51 * count will change. Multiple writers to an EA block are synchronized
52 * by the bh lock. No more than a single bh lock is held at any time
53 * to avoid deadlocks.
54 */
55
56#include <linux/buffer_head.h>
57#include <linux/module.h>
58#include <linux/init.h>
59#include <linux/slab.h>
60#include <linux/mbcache.h>
61#include <linux/quotaops.h>
62#include <linux/rwsem.h>
63#include <linux/security.h>
64#include "ext2.h"
65#include "xattr.h"
66#include "acl.h"
67
68#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
69#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
70#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
71#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
72
73#ifdef EXT2_XATTR_DEBUG
74# define ea_idebug(inode, f...) do { \
75 printk(KERN_DEBUG "inode %s:%ld: ", \
76 inode->i_sb->s_id, inode->i_ino); \
77 printk(f); \
78 printk("\n"); \
79 } while (0)
80# define ea_bdebug(bh, f...) do { \
81 char b[BDEVNAME_SIZE]; \
82 printk(KERN_DEBUG "block %s:%lu: ", \
83 bdevname(bh->b_bdev, b), \
84 (unsigned long) bh->b_blocknr); \
85 printk(f); \
86 printk("\n"); \
87 } while (0)
88#else
89# define ea_idebug(f...)
90# define ea_bdebug(f...)
91#endif
92
93static int ext2_xattr_set2(struct inode *, struct buffer_head *,
94 struct ext2_xattr_header *);
95
96static int ext2_xattr_cache_insert(struct buffer_head *);
97static struct buffer_head *ext2_xattr_cache_find(struct inode *,
98 struct ext2_xattr_header *);
99static void ext2_xattr_rehash(struct ext2_xattr_header *,
100 struct ext2_xattr_entry *);
101
102static struct mb_cache *ext2_xattr_cache;
103
104static const struct xattr_handler *ext2_xattr_handler_map[] = {
105 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
106#ifdef CONFIG_EXT2_FS_POSIX_ACL
107 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler,
108 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler,
109#endif
110 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
111#ifdef CONFIG_EXT2_FS_SECURITY
112 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
113#endif
114};
115
116const struct xattr_handler *ext2_xattr_handlers[] = {
117 &ext2_xattr_user_handler,
118 &ext2_xattr_trusted_handler,
119#ifdef CONFIG_EXT2_FS_POSIX_ACL
120 &ext2_xattr_acl_access_handler,
121 &ext2_xattr_acl_default_handler,
122#endif
123#ifdef CONFIG_EXT2_FS_SECURITY
124 &ext2_xattr_security_handler,
125#endif
126 NULL
127};
128
129static inline const struct xattr_handler *
130ext2_xattr_handler(int name_index)
131{
132 const struct xattr_handler *handler = NULL;
133
134 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
135 handler = ext2_xattr_handler_map[name_index];
136 return handler;
137}
138
139/*
140 * ext2_xattr_get()
141 *
142 * Copy an extended attribute into the buffer
143 * provided, or compute the buffer size required.
144 * Buffer is NULL to compute the size of the buffer required.
145 *
146 * Returns a negative error number on failure, or the number of bytes
147 * used / required on success.
148 */
149int
150ext2_xattr_get(struct inode *inode, int name_index, const char *name,
151 void *buffer, size_t buffer_size)
152{
153 struct buffer_head *bh = NULL;
154 struct ext2_xattr_entry *entry;
155 size_t name_len, size;
156 char *end;
157 int error;
158
159 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
160 name_index, name, buffer, (long)buffer_size);
161
162 if (name == NULL)
163 return -EINVAL;
164 name_len = strlen(name);
165 if (name_len > 255)
166 return -ERANGE;
167
168 down_read(&EXT2_I(inode)->xattr_sem);
169 error = -ENODATA;
170 if (!EXT2_I(inode)->i_file_acl)
171 goto cleanup;
172 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
173 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
174 error = -EIO;
175 if (!bh)
176 goto cleanup;
177 ea_bdebug(bh, "b_count=%d, refcount=%d",
178 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
179 end = bh->b_data + bh->b_size;
180 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
181 HDR(bh)->h_blocks != cpu_to_le32(1)) {
182bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
183 "inode %ld: bad block %d", inode->i_ino,
184 EXT2_I(inode)->i_file_acl);
185 error = -EIO;
186 goto cleanup;
187 }
188
189 /* find named attribute */
190 entry = FIRST_ENTRY(bh);
191 while (!IS_LAST_ENTRY(entry)) {
192 struct ext2_xattr_entry *next =
193 EXT2_XATTR_NEXT(entry);
194 if ((char *)next >= end)
195 goto bad_block;
196 if (name_index == entry->e_name_index &&
197 name_len == entry->e_name_len &&
198 memcmp(name, entry->e_name, name_len) == 0)
199 goto found;
200 entry = next;
201 }
202 if (ext2_xattr_cache_insert(bh))
203 ea_idebug(inode, "cache insert failed");
204 error = -ENODATA;
205 goto cleanup;
206found:
207 /* check the buffer size */
208 if (entry->e_value_block != 0)
209 goto bad_block;
210 size = le32_to_cpu(entry->e_value_size);
211 if (size > inode->i_sb->s_blocksize ||
212 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
213 goto bad_block;
214
215 if (ext2_xattr_cache_insert(bh))
216 ea_idebug(inode, "cache insert failed");
217 if (buffer) {
218 error = -ERANGE;
219 if (size > buffer_size)
220 goto cleanup;
221 /* return value of attribute */
222 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
223 size);
224 }
225 error = size;
226
227cleanup:
228 brelse(bh);
229 up_read(&EXT2_I(inode)->xattr_sem);
230
231 return error;
232}
233
234/*
235 * ext2_xattr_list()
236 *
237 * Copy a list of attribute names into the buffer
238 * provided, or compute the buffer size required.
239 * Buffer is NULL to compute the size of the buffer required.
240 *
241 * Returns a negative error number on failure, or the number of bytes
242 * used / required on success.
243 */
244static int
245ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
246{
247 struct inode *inode = dentry->d_inode;
248 struct buffer_head *bh = NULL;
249 struct ext2_xattr_entry *entry;
250 char *end;
251 size_t rest = buffer_size;
252 int error;
253
254 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
255 buffer, (long)buffer_size);
256
257 down_read(&EXT2_I(inode)->xattr_sem);
258 error = 0;
259 if (!EXT2_I(inode)->i_file_acl)
260 goto cleanup;
261 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
262 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
263 error = -EIO;
264 if (!bh)
265 goto cleanup;
266 ea_bdebug(bh, "b_count=%d, refcount=%d",
267 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
268 end = bh->b_data + bh->b_size;
269 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
270 HDR(bh)->h_blocks != cpu_to_le32(1)) {
271bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
272 "inode %ld: bad block %d", inode->i_ino,
273 EXT2_I(inode)->i_file_acl);
274 error = -EIO;
275 goto cleanup;
276 }
277
278 /* check the on-disk data structure */
279 entry = FIRST_ENTRY(bh);
280 while (!IS_LAST_ENTRY(entry)) {
281 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
282
283 if ((char *)next >= end)
284 goto bad_block;
285 entry = next;
286 }
287 if (ext2_xattr_cache_insert(bh))
288 ea_idebug(inode, "cache insert failed");
289
290 /* list the attribute names */
291 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
292 entry = EXT2_XATTR_NEXT(entry)) {
293 const struct xattr_handler *handler =
294 ext2_xattr_handler(entry->e_name_index);
295
296 if (handler) {
297 size_t size = handler->list(dentry, buffer, rest,
298 entry->e_name,
299 entry->e_name_len,
300 handler->flags);
301 if (buffer) {
302 if (size > rest) {
303 error = -ERANGE;
304 goto cleanup;
305 }
306 buffer += size;
307 }
308 rest -= size;
309 }
310 }
311 error = buffer_size - rest; /* total size */
312
313cleanup:
314 brelse(bh);
315 up_read(&EXT2_I(inode)->xattr_sem);
316
317 return error;
318}
319
320/*
321 * Inode operation listxattr()
322 *
323 * dentry->d_inode->i_mutex: don't care
324 */
325ssize_t
326ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
327{
328 return ext2_xattr_list(dentry, buffer, size);
329}
330
331/*
332 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
333 * not set, set it.
334 */
335static void ext2_xattr_update_super_block(struct super_block *sb)
336{
337 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
338 return;
339
340 spin_lock(&EXT2_SB(sb)->s_lock);
341 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
342 spin_unlock(&EXT2_SB(sb)->s_lock);
343 sb->s_dirt = 1;
344 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
345}
346
347/*
348 * ext2_xattr_set()
349 *
350 * Create, replace or remove an extended attribute for this inode. Value
351 * is NULL to remove an existing extended attribute, and non-NULL to
352 * either replace an existing extended attribute, or create a new extended
353 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
354 * specify that an extended attribute must exist and must not exist
355 * previous to the call, respectively.
356 *
357 * Returns 0, or a negative error number on failure.
358 */
359int
360ext2_xattr_set(struct inode *inode, int name_index, const char *name,
361 const void *value, size_t value_len, int flags)
362{
363 struct super_block *sb = inode->i_sb;
364 struct buffer_head *bh = NULL;
365 struct ext2_xattr_header *header = NULL;
366 struct ext2_xattr_entry *here, *last;
367 size_t name_len, free, min_offs = sb->s_blocksize;
368 int not_found = 1, error;
369 char *end;
370
371 /*
372 * header -- Points either into bh, or to a temporarily
373 * allocated buffer.
374 * here -- The named entry found, or the place for inserting, within
375 * the block pointed to by header.
376 * last -- Points right after the last named entry within the block
377 * pointed to by header.
378 * min_offs -- The offset of the first value (values are aligned
379 * towards the end of the block).
380 * end -- Points right after the block pointed to by header.
381 */
382
383 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
384 name_index, name, value, (long)value_len);
385
386 if (value == NULL)
387 value_len = 0;
388 if (name == NULL)
389 return -EINVAL;
390 name_len = strlen(name);
391 if (name_len > 255 || value_len > sb->s_blocksize)
392 return -ERANGE;
393 down_write(&EXT2_I(inode)->xattr_sem);
394 if (EXT2_I(inode)->i_file_acl) {
395 /* The inode already has an extended attribute block. */
396 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
397 error = -EIO;
398 if (!bh)
399 goto cleanup;
400 ea_bdebug(bh, "b_count=%d, refcount=%d",
401 atomic_read(&(bh->b_count)),
402 le32_to_cpu(HDR(bh)->h_refcount));
403 header = HDR(bh);
404 end = bh->b_data + bh->b_size;
405 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
406 header->h_blocks != cpu_to_le32(1)) {
407bad_block: ext2_error(sb, "ext2_xattr_set",
408 "inode %ld: bad block %d", inode->i_ino,
409 EXT2_I(inode)->i_file_acl);
410 error = -EIO;
411 goto cleanup;
412 }
413 /* Find the named attribute. */
414 here = FIRST_ENTRY(bh);
415 while (!IS_LAST_ENTRY(here)) {
416 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
417 if ((char *)next >= end)
418 goto bad_block;
419 if (!here->e_value_block && here->e_value_size) {
420 size_t offs = le16_to_cpu(here->e_value_offs);
421 if (offs < min_offs)
422 min_offs = offs;
423 }
424 not_found = name_index - here->e_name_index;
425 if (!not_found)
426 not_found = name_len - here->e_name_len;
427 if (!not_found)
428 not_found = memcmp(name, here->e_name,name_len);
429 if (not_found <= 0)
430 break;
431 here = next;
432 }
433 last = here;
434 /* We still need to compute min_offs and last. */
435 while (!IS_LAST_ENTRY(last)) {
436 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
437 if ((char *)next >= end)
438 goto bad_block;
439 if (!last->e_value_block && last->e_value_size) {
440 size_t offs = le16_to_cpu(last->e_value_offs);
441 if (offs < min_offs)
442 min_offs = offs;
443 }
444 last = next;
445 }
446
447 /* Check whether we have enough space left. */
448 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
449 } else {
450 /* We will use a new extended attribute block. */
451 free = sb->s_blocksize -
452 sizeof(struct ext2_xattr_header) - sizeof(__u32);
453 here = last = NULL; /* avoid gcc uninitialized warning. */
454 }
455
456 if (not_found) {
457 /* Request to remove a nonexistent attribute? */
458 error = -ENODATA;
459 if (flags & XATTR_REPLACE)
460 goto cleanup;
461 error = 0;
462 if (value == NULL)
463 goto cleanup;
464 } else {
465 /* Request to create an existing attribute? */
466 error = -EEXIST;
467 if (flags & XATTR_CREATE)
468 goto cleanup;
469 if (!here->e_value_block && here->e_value_size) {
470 size_t size = le32_to_cpu(here->e_value_size);
471
472 if (le16_to_cpu(here->e_value_offs) + size >
473 sb->s_blocksize || size > sb->s_blocksize)
474 goto bad_block;
475 free += EXT2_XATTR_SIZE(size);
476 }
477 free += EXT2_XATTR_LEN(name_len);
478 }
479 error = -ENOSPC;
480 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
481 goto cleanup;
482
483 /* Here we know that we can set the new attribute. */
484
485 if (header) {
486 struct mb_cache_entry *ce;
487
488 /* assert(header == HDR(bh)); */
489 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
490 bh->b_blocknr);
491 lock_buffer(bh);
492 if (header->h_refcount == cpu_to_le32(1)) {
493 ea_bdebug(bh, "modifying in-place");
494 if (ce)
495 mb_cache_entry_free(ce);
496 /* keep the buffer locked while modifying it. */
497 } else {
498 int offset;
499
500 if (ce)
501 mb_cache_entry_release(ce);
502 unlock_buffer(bh);
503 ea_bdebug(bh, "cloning");
504 header = kmalloc(bh->b_size, GFP_KERNEL);
505 error = -ENOMEM;
506 if (header == NULL)
507 goto cleanup;
508 memcpy(header, HDR(bh), bh->b_size);
509 header->h_refcount = cpu_to_le32(1);
510
511 offset = (char *)here - bh->b_data;
512 here = ENTRY((char *)header + offset);
513 offset = (char *)last - bh->b_data;
514 last = ENTRY((char *)header + offset);
515 }
516 } else {
517 /* Allocate a buffer where we construct the new block. */
518 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
519 error = -ENOMEM;
520 if (header == NULL)
521 goto cleanup;
522 end = (char *)header + sb->s_blocksize;
523 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
524 header->h_blocks = header->h_refcount = cpu_to_le32(1);
525 last = here = ENTRY(header+1);
526 }
527
528 /* Iff we are modifying the block in-place, bh is locked here. */
529
530 if (not_found) {
531 /* Insert the new name. */
532 size_t size = EXT2_XATTR_LEN(name_len);
533 size_t rest = (char *)last - (char *)here;
534 memmove((char *)here + size, here, rest);
535 memset(here, 0, size);
536 here->e_name_index = name_index;
537 here->e_name_len = name_len;
538 memcpy(here->e_name, name, name_len);
539 } else {
540 if (!here->e_value_block && here->e_value_size) {
541 char *first_val = (char *)header + min_offs;
542 size_t offs = le16_to_cpu(here->e_value_offs);
543 char *val = (char *)header + offs;
544 size_t size = EXT2_XATTR_SIZE(
545 le32_to_cpu(here->e_value_size));
546
547 if (size == EXT2_XATTR_SIZE(value_len)) {
548 /* The old and the new value have the same
549 size. Just replace. */
550 here->e_value_size = cpu_to_le32(value_len);
551 memset(val + size - EXT2_XATTR_PAD, 0,
552 EXT2_XATTR_PAD); /* Clear pad bytes. */
553 memcpy(val, value, value_len);
554 goto skip_replace;
555 }
556
557 /* Remove the old value. */
558 memmove(first_val + size, first_val, val - first_val);
559 memset(first_val, 0, size);
560 here->e_value_offs = 0;
561 min_offs += size;
562
563 /* Adjust all value offsets. */
564 last = ENTRY(header+1);
565 while (!IS_LAST_ENTRY(last)) {
566 size_t o = le16_to_cpu(last->e_value_offs);
567 if (!last->e_value_block && o < offs)
568 last->e_value_offs =
569 cpu_to_le16(o + size);
570 last = EXT2_XATTR_NEXT(last);
571 }
572 }
573 if (value == NULL) {
574 /* Remove the old name. */
575 size_t size = EXT2_XATTR_LEN(name_len);
576 last = ENTRY((char *)last - size);
577 memmove(here, (char*)here + size,
578 (char*)last - (char*)here);
579 memset(last, 0, size);
580 }
581 }
582
583 if (value != NULL) {
584 /* Insert the new value. */
585 here->e_value_size = cpu_to_le32(value_len);
586 if (value_len) {
587 size_t size = EXT2_XATTR_SIZE(value_len);
588 char *val = (char *)header + min_offs - size;
589 here->e_value_offs =
590 cpu_to_le16((char *)val - (char *)header);
591 memset(val + size - EXT2_XATTR_PAD, 0,
592 EXT2_XATTR_PAD); /* Clear the pad bytes. */
593 memcpy(val, value, value_len);
594 }
595 }
596
597skip_replace:
598 if (IS_LAST_ENTRY(ENTRY(header+1))) {
599 /* This block is now empty. */
600 if (bh && header == HDR(bh))
601 unlock_buffer(bh); /* we were modifying in-place. */
602 error = ext2_xattr_set2(inode, bh, NULL);
603 } else {
604 ext2_xattr_rehash(header, here);
605 if (bh && header == HDR(bh))
606 unlock_buffer(bh); /* we were modifying in-place. */
607 error = ext2_xattr_set2(inode, bh, header);
608 }
609
610cleanup:
611 brelse(bh);
612 if (!(bh && header == HDR(bh)))
613 kfree(header);
614 up_write(&EXT2_I(inode)->xattr_sem);
615
616 return error;
617}
618
619/*
620 * Second half of ext2_xattr_set(): Update the file system.
621 */
622static int
623ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
624 struct ext2_xattr_header *header)
625{
626 struct super_block *sb = inode->i_sb;
627 struct buffer_head *new_bh = NULL;
628 int error;
629
630 if (header) {
631 new_bh = ext2_xattr_cache_find(inode, header);
632 if (new_bh) {
633 /* We found an identical block in the cache. */
634 if (new_bh == old_bh) {
635 ea_bdebug(new_bh, "keeping this block");
636 } else {
637 /* The old block is released after updating
638 the inode. */
639 ea_bdebug(new_bh, "reusing block");
640
641 error = dquot_alloc_block(inode, 1);
642 if (error) {
643 unlock_buffer(new_bh);
644 goto cleanup;
645 }
646 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
647 ea_bdebug(new_bh, "refcount now=%d",
648 le32_to_cpu(HDR(new_bh)->h_refcount));
649 }
650 unlock_buffer(new_bh);
651 } else if (old_bh && header == HDR(old_bh)) {
652 /* Keep this block. No need to lock the block as we
653 don't need to change the reference count. */
654 new_bh = old_bh;
655 get_bh(new_bh);
656 ext2_xattr_cache_insert(new_bh);
657 } else {
658 /* We need to allocate a new block */
659 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
660 EXT2_I(inode)->i_block_group);
661 int block = ext2_new_block(inode, goal, &error);
662 if (error)
663 goto cleanup;
664 ea_idebug(inode, "creating block %d", block);
665
666 new_bh = sb_getblk(sb, block);
667 if (!new_bh) {
668 ext2_free_blocks(inode, block, 1);
669 mark_inode_dirty(inode);
670 error = -EIO;
671 goto cleanup;
672 }
673 lock_buffer(new_bh);
674 memcpy(new_bh->b_data, header, new_bh->b_size);
675 set_buffer_uptodate(new_bh);
676 unlock_buffer(new_bh);
677 ext2_xattr_cache_insert(new_bh);
678
679 ext2_xattr_update_super_block(sb);
680 }
681 mark_buffer_dirty(new_bh);
682 if (IS_SYNC(inode)) {
683 sync_dirty_buffer(new_bh);
684 error = -EIO;
685 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
686 goto cleanup;
687 }
688 }
689
690 /* Update the inode. */
691 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
692 inode->i_ctime = CURRENT_TIME_SEC;
693 if (IS_SYNC(inode)) {
694 error = sync_inode_metadata(inode, 1);
695 /* In case sync failed due to ENOSPC the inode was actually
696 * written (only some dirty data were not) so we just proceed
697 * as if nothing happened and cleanup the unused block */
698 if (error && error != -ENOSPC) {
699 if (new_bh && new_bh != old_bh) {
700 dquot_free_block_nodirty(inode, 1);
701 mark_inode_dirty(inode);
702 }
703 goto cleanup;
704 }
705 } else
706 mark_inode_dirty(inode);
707
708 error = 0;
709 if (old_bh && old_bh != new_bh) {
710 struct mb_cache_entry *ce;
711
712 /*
713 * If there was an old block and we are no longer using it,
714 * release the old block.
715 */
716 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
717 old_bh->b_blocknr);
718 lock_buffer(old_bh);
719 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
720 /* Free the old block. */
721 if (ce)
722 mb_cache_entry_free(ce);
723 ea_bdebug(old_bh, "freeing");
724 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
725 mark_inode_dirty(inode);
726 /* We let our caller release old_bh, so we
727 * need to duplicate the buffer before. */
728 get_bh(old_bh);
729 bforget(old_bh);
730 } else {
731 /* Decrement the refcount only. */
732 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
733 if (ce)
734 mb_cache_entry_release(ce);
735 dquot_free_block_nodirty(inode, 1);
736 mark_inode_dirty(inode);
737 mark_buffer_dirty(old_bh);
738 ea_bdebug(old_bh, "refcount now=%d",
739 le32_to_cpu(HDR(old_bh)->h_refcount));
740 }
741 unlock_buffer(old_bh);
742 }
743
744cleanup:
745 brelse(new_bh);
746
747 return error;
748}
749
750/*
751 * ext2_xattr_delete_inode()
752 *
753 * Free extended attribute resources associated with this inode. This
754 * is called immediately before an inode is freed.
755 */
756void
757ext2_xattr_delete_inode(struct inode *inode)
758{
759 struct buffer_head *bh = NULL;
760 struct mb_cache_entry *ce;
761
762 down_write(&EXT2_I(inode)->xattr_sem);
763 if (!EXT2_I(inode)->i_file_acl)
764 goto cleanup;
765 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
766 if (!bh) {
767 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
768 "inode %ld: block %d read error", inode->i_ino,
769 EXT2_I(inode)->i_file_acl);
770 goto cleanup;
771 }
772 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
773 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
774 HDR(bh)->h_blocks != cpu_to_le32(1)) {
775 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
776 "inode %ld: bad block %d", inode->i_ino,
777 EXT2_I(inode)->i_file_acl);
778 goto cleanup;
779 }
780 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
781 lock_buffer(bh);
782 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
783 if (ce)
784 mb_cache_entry_free(ce);
785 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
786 get_bh(bh);
787 bforget(bh);
788 unlock_buffer(bh);
789 } else {
790 le32_add_cpu(&HDR(bh)->h_refcount, -1);
791 if (ce)
792 mb_cache_entry_release(ce);
793 ea_bdebug(bh, "refcount now=%d",
794 le32_to_cpu(HDR(bh)->h_refcount));
795 unlock_buffer(bh);
796 mark_buffer_dirty(bh);
797 if (IS_SYNC(inode))
798 sync_dirty_buffer(bh);
799 dquot_free_block_nodirty(inode, 1);
800 }
801 EXT2_I(inode)->i_file_acl = 0;
802
803cleanup:
804 brelse(bh);
805 up_write(&EXT2_I(inode)->xattr_sem);
806}
807
808/*
809 * ext2_xattr_put_super()
810 *
811 * This is called when a file system is unmounted.
812 */
813void
814ext2_xattr_put_super(struct super_block *sb)
815{
816 mb_cache_shrink(sb->s_bdev);
817}
818
819
820/*
821 * ext2_xattr_cache_insert()
822 *
823 * Create a new entry in the extended attribute cache, and insert
824 * it unless such an entry is already in the cache.
825 *
826 * Returns 0, or a negative error number on failure.
827 */
828static int
829ext2_xattr_cache_insert(struct buffer_head *bh)
830{
831 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
832 struct mb_cache_entry *ce;
833 int error;
834
835 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
836 if (!ce)
837 return -ENOMEM;
838 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
839 if (error) {
840 mb_cache_entry_free(ce);
841 if (error == -EBUSY) {
842 ea_bdebug(bh, "already in cache (%d cache entries)",
843 atomic_read(&ext2_xattr_cache->c_entry_count));
844 error = 0;
845 }
846 } else {
847 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
848 atomic_read(&ext2_xattr_cache->c_entry_count));
849 mb_cache_entry_release(ce);
850 }
851 return error;
852}
853
854/*
855 * ext2_xattr_cmp()
856 *
857 * Compare two extended attribute blocks for equality.
858 *
859 * Returns 0 if the blocks are equal, 1 if they differ, and
860 * a negative error number on errors.
861 */
862static int
863ext2_xattr_cmp(struct ext2_xattr_header *header1,
864 struct ext2_xattr_header *header2)
865{
866 struct ext2_xattr_entry *entry1, *entry2;
867
868 entry1 = ENTRY(header1+1);
869 entry2 = ENTRY(header2+1);
870 while (!IS_LAST_ENTRY(entry1)) {
871 if (IS_LAST_ENTRY(entry2))
872 return 1;
873 if (entry1->e_hash != entry2->e_hash ||
874 entry1->e_name_index != entry2->e_name_index ||
875 entry1->e_name_len != entry2->e_name_len ||
876 entry1->e_value_size != entry2->e_value_size ||
877 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
878 return 1;
879 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
880 return -EIO;
881 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
882 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
883 le32_to_cpu(entry1->e_value_size)))
884 return 1;
885
886 entry1 = EXT2_XATTR_NEXT(entry1);
887 entry2 = EXT2_XATTR_NEXT(entry2);
888 }
889 if (!IS_LAST_ENTRY(entry2))
890 return 1;
891 return 0;
892}
893
894/*
895 * ext2_xattr_cache_find()
896 *
897 * Find an identical extended attribute block.
898 *
899 * Returns a locked buffer head to the block found, or NULL if such
900 * a block was not found or an error occurred.
901 */
902static struct buffer_head *
903ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
904{
905 __u32 hash = le32_to_cpu(header->h_hash);
906 struct mb_cache_entry *ce;
907
908 if (!header->h_hash)
909 return NULL; /* never share */
910 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
911again:
912 ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev,
913 hash);
914 while (ce) {
915 struct buffer_head *bh;
916
917 if (IS_ERR(ce)) {
918 if (PTR_ERR(ce) == -EAGAIN)
919 goto again;
920 break;
921 }
922
923 bh = sb_bread(inode->i_sb, ce->e_block);
924 if (!bh) {
925 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
926 "inode %ld: block %ld read error",
927 inode->i_ino, (unsigned long) ce->e_block);
928 } else {
929 lock_buffer(bh);
930 if (le32_to_cpu(HDR(bh)->h_refcount) >
931 EXT2_XATTR_REFCOUNT_MAX) {
932 ea_idebug(inode, "block %ld refcount %d>%d",
933 (unsigned long) ce->e_block,
934 le32_to_cpu(HDR(bh)->h_refcount),
935 EXT2_XATTR_REFCOUNT_MAX);
936 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
937 ea_bdebug(bh, "b_count=%d",
938 atomic_read(&(bh->b_count)));
939 mb_cache_entry_release(ce);
940 return bh;
941 }
942 unlock_buffer(bh);
943 brelse(bh);
944 }
945 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
946 }
947 return NULL;
948}
949
950#define NAME_HASH_SHIFT 5
951#define VALUE_HASH_SHIFT 16
952
953/*
954 * ext2_xattr_hash_entry()
955 *
956 * Compute the hash of an extended attribute.
957 */
958static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
959 struct ext2_xattr_entry *entry)
960{
961 __u32 hash = 0;
962 char *name = entry->e_name;
963 int n;
964
965 for (n=0; n < entry->e_name_len; n++) {
966 hash = (hash << NAME_HASH_SHIFT) ^
967 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
968 *name++;
969 }
970
971 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
972 __le32 *value = (__le32 *)((char *)header +
973 le16_to_cpu(entry->e_value_offs));
974 for (n = (le32_to_cpu(entry->e_value_size) +
975 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
976 hash = (hash << VALUE_HASH_SHIFT) ^
977 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
978 le32_to_cpu(*value++);
979 }
980 }
981 entry->e_hash = cpu_to_le32(hash);
982}
983
984#undef NAME_HASH_SHIFT
985#undef VALUE_HASH_SHIFT
986
987#define BLOCK_HASH_SHIFT 16
988
989/*
990 * ext2_xattr_rehash()
991 *
992 * Re-compute the extended attribute hash value after an entry has changed.
993 */
994static void ext2_xattr_rehash(struct ext2_xattr_header *header,
995 struct ext2_xattr_entry *entry)
996{
997 struct ext2_xattr_entry *here;
998 __u32 hash = 0;
999
1000 ext2_xattr_hash_entry(header, entry);
1001 here = ENTRY(header+1);
1002 while (!IS_LAST_ENTRY(here)) {
1003 if (!here->e_hash) {
1004 /* Block is not shared if an entry's hash value == 0 */
1005 hash = 0;
1006 break;
1007 }
1008 hash = (hash << BLOCK_HASH_SHIFT) ^
1009 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1010 le32_to_cpu(here->e_hash);
1011 here = EXT2_XATTR_NEXT(here);
1012 }
1013 header->h_hash = cpu_to_le32(hash);
1014}
1015
1016#undef BLOCK_HASH_SHIFT
1017
1018int __init
1019init_ext2_xattr(void)
1020{
1021 ext2_xattr_cache = mb_cache_create("ext2_xattr", 6);
1022 if (!ext2_xattr_cache)
1023 return -ENOMEM;
1024 return 0;
1025}
1026
1027void
1028exit_ext2_xattr(void)
1029{
1030 mb_cache_destroy(ext2_xattr_cache);
1031}