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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 *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] = &posix_acl_access_xattr_handler,
105 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
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 *ext2_xattr_handlers[] = {
114 &ext2_xattr_user_handler,
115 &ext2_xattr_trusted_handler,
116#ifdef CONFIG_EXT2_FS_POSIX_ACL
117 &posix_acl_access_xattr_handler,
118 &posix_acl_default_xattr_handler,
119#endif
120#ifdef CONFIG_EXT2_FS_SECURITY
121 &ext2_xattr_security_handler,
122#endif
123 NULL
124};
125
126#define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache)
127
128static inline const struct xattr_handler *
129ext2_xattr_handler(int name_index)
130{
131 const struct xattr_handler *handler = NULL;
132
133 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
134 handler = ext2_xattr_handler_map[name_index];
135 return 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 struct xattr_handler *handler =
337 ext2_xattr_handler(entry->e_name_index);
338
339 if (handler && (!handler->list || handler->list(dentry))) {
340 const char *prefix = handler->prefix ?: handler->name;
341 size_t prefix_len = strlen(prefix);
342 size_t size = prefix_len + entry->e_name_len + 1;
343
344 if (buffer) {
345 if (size > rest) {
346 error = -ERANGE;
347 goto cleanup;
348 }
349 memcpy(buffer, prefix, prefix_len);
350 buffer += prefix_len;
351 memcpy(buffer, entry->e_name, entry->e_name_len);
352 buffer += entry->e_name_len;
353 *buffer++ = 0;
354 }
355 rest -= size;
356 }
357 }
358 error = buffer_size - rest; /* total size */
359
360cleanup:
361 brelse(bh);
362 up_read(&EXT2_I(inode)->xattr_sem);
363
364 return error;
365}
366
367/*
368 * Inode operation listxattr()
369 *
370 * d_inode(dentry)->i_mutex: don't care
371 */
372ssize_t
373ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
374{
375 return ext2_xattr_list(dentry, buffer, size);
376}
377
378/*
379 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
380 * not set, set it.
381 */
382static void ext2_xattr_update_super_block(struct super_block *sb)
383{
384 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
385 return;
386
387 spin_lock(&EXT2_SB(sb)->s_lock);
388 ext2_update_dynamic_rev(sb);
389 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
390 spin_unlock(&EXT2_SB(sb)->s_lock);
391 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
392}
393
394/*
395 * ext2_xattr_set()
396 *
397 * Create, replace or remove an extended attribute for this inode. Value
398 * is NULL to remove an existing extended attribute, and non-NULL to
399 * either replace an existing extended attribute, or create a new extended
400 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
401 * specify that an extended attribute must exist and must not exist
402 * previous to the call, respectively.
403 *
404 * Returns 0, or a negative error number on failure.
405 */
406int
407ext2_xattr_set(struct inode *inode, int name_index, const char *name,
408 const void *value, size_t value_len, int flags)
409{
410 struct super_block *sb = inode->i_sb;
411 struct buffer_head *bh = NULL;
412 struct ext2_xattr_header *header = NULL;
413 struct ext2_xattr_entry *here = NULL, *last = NULL;
414 size_t name_len, free, min_offs = sb->s_blocksize;
415 int not_found = 1, error;
416 char *end;
417
418 /*
419 * header -- Points either into bh, or to a temporarily
420 * allocated buffer.
421 * here -- The named entry found, or the place for inserting, within
422 * the block pointed to by header.
423 * last -- Points right after the last named entry within the block
424 * pointed to by header.
425 * min_offs -- The offset of the first value (values are aligned
426 * towards the end of the block).
427 * end -- Points right after the block pointed to by header.
428 */
429
430 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
431 name_index, name, value, (long)value_len);
432
433 if (value == NULL)
434 value_len = 0;
435 if (name == NULL)
436 return -EINVAL;
437 name_len = strlen(name);
438 if (name_len > 255 || value_len > sb->s_blocksize)
439 return -ERANGE;
440 error = dquot_initialize(inode);
441 if (error)
442 return error;
443 down_write(&EXT2_I(inode)->xattr_sem);
444 if (EXT2_I(inode)->i_file_acl) {
445 /* The inode already has an extended attribute block. */
446 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
447 error = -EIO;
448 if (!bh)
449 goto cleanup;
450 ea_bdebug(bh, "b_count=%d, refcount=%d",
451 atomic_read(&(bh->b_count)),
452 le32_to_cpu(HDR(bh)->h_refcount));
453 header = HDR(bh);
454 end = bh->b_data + bh->b_size;
455 if (!ext2_xattr_header_valid(header)) {
456bad_block:
457 ext2_error(sb, "ext2_xattr_set",
458 "inode %ld: bad block %d", inode->i_ino,
459 EXT2_I(inode)->i_file_acl);
460 error = -EIO;
461 goto cleanup;
462 }
463 /*
464 * Find the named attribute. If not found, 'here' will point
465 * to entry where the new attribute should be inserted to
466 * maintain sorting.
467 */
468 last = FIRST_ENTRY(bh);
469 while (!IS_LAST_ENTRY(last)) {
470 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize))
471 goto bad_block;
472 if (last->e_value_size) {
473 size_t offs = le16_to_cpu(last->e_value_offs);
474 if (offs < min_offs)
475 min_offs = offs;
476 }
477 if (not_found > 0) {
478 not_found = ext2_xattr_cmp_entry(name_index,
479 name_len,
480 name, last);
481 if (not_found <= 0)
482 here = last;
483 }
484 last = EXT2_XATTR_NEXT(last);
485 }
486 if (not_found > 0)
487 here = last;
488
489 /* Check whether we have enough space left. */
490 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
491 } else {
492 /* We will use a new extended attribute block. */
493 free = sb->s_blocksize -
494 sizeof(struct ext2_xattr_header) - sizeof(__u32);
495 }
496
497 if (not_found) {
498 /* Request to remove a nonexistent attribute? */
499 error = -ENODATA;
500 if (flags & XATTR_REPLACE)
501 goto cleanup;
502 error = 0;
503 if (value == NULL)
504 goto cleanup;
505 } else {
506 /* Request to create an existing attribute? */
507 error = -EEXIST;
508 if (flags & XATTR_CREATE)
509 goto cleanup;
510 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size));
511 free += EXT2_XATTR_LEN(name_len);
512 }
513 error = -ENOSPC;
514 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
515 goto cleanup;
516
517 /* Here we know that we can set the new attribute. */
518
519 if (header) {
520 int offset;
521
522 lock_buffer(bh);
523 if (header->h_refcount == cpu_to_le32(1)) {
524 __u32 hash = le32_to_cpu(header->h_hash);
525 struct mb_cache_entry *oe;
526
527 oe = mb_cache_entry_delete_or_get(EA_BLOCK_CACHE(inode),
528 hash, bh->b_blocknr);
529 if (!oe) {
530 ea_bdebug(bh, "modifying in-place");
531 goto update_block;
532 }
533 /*
534 * Someone is trying to reuse the block, leave it alone
535 */
536 mb_cache_entry_put(EA_BLOCK_CACHE(inode), oe);
537 }
538 unlock_buffer(bh);
539 ea_bdebug(bh, "cloning");
540 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL);
541 error = -ENOMEM;
542 if (header == NULL)
543 goto cleanup;
544 header->h_refcount = cpu_to_le32(1);
545
546 offset = (char *)here - bh->b_data;
547 here = ENTRY((char *)header + offset);
548 offset = (char *)last - bh->b_data;
549 last = ENTRY((char *)header + offset);
550 } else {
551 /* Allocate a buffer where we construct the new block. */
552 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
553 error = -ENOMEM;
554 if (header == NULL)
555 goto cleanup;
556 end = (char *)header + sb->s_blocksize;
557 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
558 header->h_blocks = header->h_refcount = cpu_to_le32(1);
559 last = here = ENTRY(header+1);
560 }
561
562update_block:
563 /* Iff we are modifying the block in-place, bh is locked here. */
564
565 if (not_found) {
566 /* Insert the new name. */
567 size_t size = EXT2_XATTR_LEN(name_len);
568 size_t rest = (char *)last - (char *)here;
569 memmove((char *)here + size, here, rest);
570 memset(here, 0, size);
571 here->e_name_index = name_index;
572 here->e_name_len = name_len;
573 memcpy(here->e_name, name, name_len);
574 } else {
575 if (here->e_value_size) {
576 char *first_val = (char *)header + min_offs;
577 size_t offs = le16_to_cpu(here->e_value_offs);
578 char *val = (char *)header + offs;
579 size_t size = EXT2_XATTR_SIZE(
580 le32_to_cpu(here->e_value_size));
581
582 if (size == EXT2_XATTR_SIZE(value_len)) {
583 /* The old and the new value have the same
584 size. Just replace. */
585 here->e_value_size = cpu_to_le32(value_len);
586 memset(val + size - EXT2_XATTR_PAD, 0,
587 EXT2_XATTR_PAD); /* Clear pad bytes. */
588 memcpy(val, value, value_len);
589 goto skip_replace;
590 }
591
592 /* Remove the old value. */
593 memmove(first_val + size, first_val, val - first_val);
594 memset(first_val, 0, size);
595 min_offs += size;
596
597 /* Adjust all value offsets. */
598 last = ENTRY(header+1);
599 while (!IS_LAST_ENTRY(last)) {
600 size_t o = le16_to_cpu(last->e_value_offs);
601 if (o < offs)
602 last->e_value_offs =
603 cpu_to_le16(o + size);
604 last = EXT2_XATTR_NEXT(last);
605 }
606
607 here->e_value_offs = 0;
608 }
609 if (value == NULL) {
610 /* Remove the old name. */
611 size_t size = EXT2_XATTR_LEN(name_len);
612 last = ENTRY((char *)last - size);
613 memmove(here, (char*)here + size,
614 (char*)last - (char*)here);
615 memset(last, 0, size);
616 }
617 }
618
619 if (value != NULL) {
620 /* Insert the new value. */
621 here->e_value_size = cpu_to_le32(value_len);
622 if (value_len) {
623 size_t size = EXT2_XATTR_SIZE(value_len);
624 char *val = (char *)header + min_offs - size;
625 here->e_value_offs =
626 cpu_to_le16((char *)val - (char *)header);
627 memset(val + size - EXT2_XATTR_PAD, 0,
628 EXT2_XATTR_PAD); /* Clear the pad bytes. */
629 memcpy(val, value, value_len);
630 }
631 }
632
633skip_replace:
634 if (IS_LAST_ENTRY(ENTRY(header+1))) {
635 /* This block is now empty. */
636 if (bh && header == HDR(bh))
637 unlock_buffer(bh); /* we were modifying in-place. */
638 error = ext2_xattr_set2(inode, bh, NULL);
639 } else {
640 ext2_xattr_rehash(header, here);
641 if (bh && header == HDR(bh))
642 unlock_buffer(bh); /* we were modifying in-place. */
643 error = ext2_xattr_set2(inode, bh, header);
644 }
645
646cleanup:
647 if (!(bh && header == HDR(bh)))
648 kfree(header);
649 brelse(bh);
650 up_write(&EXT2_I(inode)->xattr_sem);
651
652 return error;
653}
654
655static void ext2_xattr_release_block(struct inode *inode,
656 struct buffer_head *bh)
657{
658 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
659
660retry_ref:
661 lock_buffer(bh);
662 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
663 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
664 struct mb_cache_entry *oe;
665
666 /*
667 * This must happen under buffer lock to properly
668 * serialize with ext2_xattr_set() reusing the block.
669 */
670 oe = mb_cache_entry_delete_or_get(ea_block_cache, hash,
671 bh->b_blocknr);
672 if (oe) {
673 /*
674 * Someone is trying to reuse the block. Wait
675 * and retry.
676 */
677 unlock_buffer(bh);
678 mb_cache_entry_wait_unused(oe);
679 mb_cache_entry_put(ea_block_cache, oe);
680 goto retry_ref;
681 }
682
683 /* Free the old block. */
684 ea_bdebug(bh, "freeing");
685 ext2_free_blocks(inode, bh->b_blocknr, 1);
686 /* We let our caller release bh, so we
687 * need to duplicate the buffer before. */
688 get_bh(bh);
689 bforget(bh);
690 unlock_buffer(bh);
691 } else {
692 /* Decrement the refcount only. */
693 le32_add_cpu(&HDR(bh)->h_refcount, -1);
694 dquot_free_block(inode, 1);
695 mark_buffer_dirty(bh);
696 unlock_buffer(bh);
697 ea_bdebug(bh, "refcount now=%d",
698 le32_to_cpu(HDR(bh)->h_refcount));
699 if (IS_SYNC(inode))
700 sync_dirty_buffer(bh);
701 }
702}
703
704/*
705 * Second half of ext2_xattr_set(): Update the file system.
706 */
707static int
708ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
709 struct ext2_xattr_header *header)
710{
711 struct super_block *sb = inode->i_sb;
712 struct buffer_head *new_bh = NULL;
713 int error;
714 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
715
716 if (header) {
717 new_bh = ext2_xattr_cache_find(inode, header);
718 if (new_bh) {
719 /* We found an identical block in the cache. */
720 if (new_bh == old_bh) {
721 ea_bdebug(new_bh, "keeping this block");
722 } else {
723 /* The old block is released after updating
724 the inode. */
725 ea_bdebug(new_bh, "reusing block");
726
727 error = dquot_alloc_block(inode, 1);
728 if (error) {
729 unlock_buffer(new_bh);
730 goto cleanup;
731 }
732 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
733 ea_bdebug(new_bh, "refcount now=%d",
734 le32_to_cpu(HDR(new_bh)->h_refcount));
735 }
736 unlock_buffer(new_bh);
737 } else if (old_bh && header == HDR(old_bh)) {
738 /* Keep this block. No need to lock the block as we
739 don't need to change the reference count. */
740 new_bh = old_bh;
741 get_bh(new_bh);
742 ext2_xattr_cache_insert(ea_block_cache, new_bh);
743 } else {
744 /* We need to allocate a new block */
745 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
746 EXT2_I(inode)->i_block_group);
747 int block = ext2_new_block(inode, goal, &error);
748 if (error)
749 goto cleanup;
750 ea_idebug(inode, "creating block %d", block);
751
752 new_bh = sb_getblk(sb, block);
753 if (unlikely(!new_bh)) {
754 ext2_free_blocks(inode, block, 1);
755 mark_inode_dirty(inode);
756 error = -ENOMEM;
757 goto cleanup;
758 }
759 lock_buffer(new_bh);
760 memcpy(new_bh->b_data, header, new_bh->b_size);
761 set_buffer_uptodate(new_bh);
762 unlock_buffer(new_bh);
763 ext2_xattr_cache_insert(ea_block_cache, new_bh);
764
765 ext2_xattr_update_super_block(sb);
766 }
767 mark_buffer_dirty(new_bh);
768 if (IS_SYNC(inode)) {
769 sync_dirty_buffer(new_bh);
770 error = -EIO;
771 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
772 goto cleanup;
773 }
774 }
775
776 /* Update the inode. */
777 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
778 inode->i_ctime = current_time(inode);
779 if (IS_SYNC(inode)) {
780 error = sync_inode_metadata(inode, 1);
781 /* In case sync failed due to ENOSPC the inode was actually
782 * written (only some dirty data were not) so we just proceed
783 * as if nothing happened and cleanup the unused block */
784 if (error && error != -ENOSPC) {
785 if (new_bh && new_bh != old_bh) {
786 dquot_free_block_nodirty(inode, 1);
787 mark_inode_dirty(inode);
788 }
789 goto cleanup;
790 }
791 } else
792 mark_inode_dirty(inode);
793
794 error = 0;
795 if (old_bh && old_bh != new_bh) {
796 /*
797 * If there was an old block and we are no longer using it,
798 * release the old block.
799 */
800 ext2_xattr_release_block(inode, old_bh);
801 }
802
803cleanup:
804 brelse(new_bh);
805
806 return error;
807}
808
809/*
810 * ext2_xattr_delete_inode()
811 *
812 * Free extended attribute resources associated with this inode. This
813 * is called immediately before an inode is freed.
814 */
815void
816ext2_xattr_delete_inode(struct inode *inode)
817{
818 struct buffer_head *bh = NULL;
819 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
820
821 /*
822 * We are the only ones holding inode reference. The xattr_sem should
823 * better be unlocked! We could as well just not acquire xattr_sem at
824 * all but this makes the code more futureproof. OTOH we need trylock
825 * here to avoid false-positive warning from lockdep about reclaim
826 * circular dependency.
827 */
828 if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem)))
829 return;
830 if (!EXT2_I(inode)->i_file_acl)
831 goto cleanup;
832
833 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) {
834 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
835 "inode %ld: xattr block %d is out of data blocks range",
836 inode->i_ino, EXT2_I(inode)->i_file_acl);
837 goto cleanup;
838 }
839
840 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
841 if (!bh) {
842 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
843 "inode %ld: block %d read error", inode->i_ino,
844 EXT2_I(inode)->i_file_acl);
845 goto cleanup;
846 }
847 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
848 if (!ext2_xattr_header_valid(HDR(bh))) {
849 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
850 "inode %ld: bad block %d", inode->i_ino,
851 EXT2_I(inode)->i_file_acl);
852 goto cleanup;
853 }
854 ext2_xattr_release_block(inode, bh);
855 EXT2_I(inode)->i_file_acl = 0;
856
857cleanup:
858 brelse(bh);
859 up_write(&EXT2_I(inode)->xattr_sem);
860}
861
862/*
863 * ext2_xattr_cache_insert()
864 *
865 * Create a new entry in the extended attribute cache, and insert
866 * it unless such an entry is already in the cache.
867 *
868 * Returns 0, or a negative error number on failure.
869 */
870static int
871ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)
872{
873 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
874 int error;
875
876 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr,
877 true);
878 if (error) {
879 if (error == -EBUSY) {
880 ea_bdebug(bh, "already in cache");
881 error = 0;
882 }
883 } else
884 ea_bdebug(bh, "inserting [%x]", (int)hash);
885 return error;
886}
887
888/*
889 * ext2_xattr_cmp()
890 *
891 * Compare two extended attribute blocks for equality.
892 *
893 * Returns 0 if the blocks are equal, 1 if they differ, and
894 * a negative error number on errors.
895 */
896static int
897ext2_xattr_cmp(struct ext2_xattr_header *header1,
898 struct ext2_xattr_header *header2)
899{
900 struct ext2_xattr_entry *entry1, *entry2;
901
902 entry1 = ENTRY(header1+1);
903 entry2 = ENTRY(header2+1);
904 while (!IS_LAST_ENTRY(entry1)) {
905 if (IS_LAST_ENTRY(entry2))
906 return 1;
907 if (entry1->e_hash != entry2->e_hash ||
908 entry1->e_name_index != entry2->e_name_index ||
909 entry1->e_name_len != entry2->e_name_len ||
910 entry1->e_value_size != entry2->e_value_size ||
911 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
912 return 1;
913 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
914 return -EIO;
915 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
916 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
917 le32_to_cpu(entry1->e_value_size)))
918 return 1;
919
920 entry1 = EXT2_XATTR_NEXT(entry1);
921 entry2 = EXT2_XATTR_NEXT(entry2);
922 }
923 if (!IS_LAST_ENTRY(entry2))
924 return 1;
925 return 0;
926}
927
928/*
929 * ext2_xattr_cache_find()
930 *
931 * Find an identical extended attribute block.
932 *
933 * Returns a locked buffer head to the block found, or NULL if such
934 * a block was not found or an error occurred.
935 */
936static struct buffer_head *
937ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
938{
939 __u32 hash = le32_to_cpu(header->h_hash);
940 struct mb_cache_entry *ce;
941 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
942
943 if (!header->h_hash)
944 return NULL; /* never share */
945 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
946
947 ce = mb_cache_entry_find_first(ea_block_cache, hash);
948 while (ce) {
949 struct buffer_head *bh;
950
951 bh = sb_bread(inode->i_sb, ce->e_value);
952 if (!bh) {
953 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
954 "inode %ld: block %ld read error",
955 inode->i_ino, (unsigned long) ce->e_value);
956 } else {
957 lock_buffer(bh);
958 if (le32_to_cpu(HDR(bh)->h_refcount) >
959 EXT2_XATTR_REFCOUNT_MAX) {
960 ea_idebug(inode, "block %ld refcount %d>%d",
961 (unsigned long) ce->e_value,
962 le32_to_cpu(HDR(bh)->h_refcount),
963 EXT2_XATTR_REFCOUNT_MAX);
964 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
965 ea_bdebug(bh, "b_count=%d",
966 atomic_read(&(bh->b_count)));
967 mb_cache_entry_touch(ea_block_cache, ce);
968 mb_cache_entry_put(ea_block_cache, ce);
969 return bh;
970 }
971 unlock_buffer(bh);
972 brelse(bh);
973 }
974 ce = mb_cache_entry_find_next(ea_block_cache, ce);
975 }
976 return NULL;
977}
978
979#define NAME_HASH_SHIFT 5
980#define VALUE_HASH_SHIFT 16
981
982/*
983 * ext2_xattr_hash_entry()
984 *
985 * Compute the hash of an extended attribute.
986 */
987static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
988 struct ext2_xattr_entry *entry)
989{
990 __u32 hash = 0;
991 char *name = entry->e_name;
992 int n;
993
994 for (n=0; n < entry->e_name_len; n++) {
995 hash = (hash << NAME_HASH_SHIFT) ^
996 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
997 *name++;
998 }
999
1000 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1001 __le32 *value = (__le32 *)((char *)header +
1002 le16_to_cpu(entry->e_value_offs));
1003 for (n = (le32_to_cpu(entry->e_value_size) +
1004 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
1005 hash = (hash << VALUE_HASH_SHIFT) ^
1006 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1007 le32_to_cpu(*value++);
1008 }
1009 }
1010 entry->e_hash = cpu_to_le32(hash);
1011}
1012
1013#undef NAME_HASH_SHIFT
1014#undef VALUE_HASH_SHIFT
1015
1016#define BLOCK_HASH_SHIFT 16
1017
1018/*
1019 * ext2_xattr_rehash()
1020 *
1021 * Re-compute the extended attribute hash value after an entry has changed.
1022 */
1023static void ext2_xattr_rehash(struct ext2_xattr_header *header,
1024 struct ext2_xattr_entry *entry)
1025{
1026 struct ext2_xattr_entry *here;
1027 __u32 hash = 0;
1028
1029 ext2_xattr_hash_entry(header, entry);
1030 here = ENTRY(header+1);
1031 while (!IS_LAST_ENTRY(here)) {
1032 if (!here->e_hash) {
1033 /* Block is not shared if an entry's hash value == 0 */
1034 hash = 0;
1035 break;
1036 }
1037 hash = (hash << BLOCK_HASH_SHIFT) ^
1038 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1039 le32_to_cpu(here->e_hash);
1040 here = EXT2_XATTR_NEXT(here);
1041 }
1042 header->h_hash = cpu_to_le32(hash);
1043}
1044
1045#undef BLOCK_HASH_SHIFT
1046
1047#define HASH_BUCKET_BITS 10
1048
1049struct mb_cache *ext2_xattr_create_cache(void)
1050{
1051 return mb_cache_create(HASH_BUCKET_BITS);
1052}
1053
1054void ext2_xattr_destroy_cache(struct mb_cache *cache)
1055{
1056 if (cache)
1057 mb_cache_destroy(cache);
1058}
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}