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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/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 printk(KERN_DEBUG "block %pg:%lu: ", \
82 bh->b_bdev, (unsigned long) bh->b_blocknr); \
83 printk(f); \
84 printk("\n"); \
85 } while (0)
86#else
87# define ea_idebug(f...)
88# define ea_bdebug(f...)
89#endif
90
91static int ext2_xattr_set2(struct inode *, struct buffer_head *,
92 struct ext2_xattr_header *);
93
94static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
95static struct buffer_head *ext2_xattr_cache_find(struct inode *,
96 struct ext2_xattr_header *);
97static void ext2_xattr_rehash(struct ext2_xattr_header *,
98 struct ext2_xattr_entry *);
99
100static const struct xattr_handler *ext2_xattr_handler_map[] = {
101 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
102#ifdef CONFIG_EXT2_FS_POSIX_ACL
103 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler,
104 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
105#endif
106 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
107#ifdef CONFIG_EXT2_FS_SECURITY
108 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
109#endif
110};
111
112const struct xattr_handler *ext2_xattr_handlers[] = {
113 &ext2_xattr_user_handler,
114 &ext2_xattr_trusted_handler,
115#ifdef CONFIG_EXT2_FS_POSIX_ACL
116 &posix_acl_access_xattr_handler,
117 &posix_acl_default_xattr_handler,
118#endif
119#ifdef CONFIG_EXT2_FS_SECURITY
120 &ext2_xattr_security_handler,
121#endif
122 NULL
123};
124
125#define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache)
126
127static inline const struct xattr_handler *
128ext2_xattr_handler(int name_index)
129{
130 const struct xattr_handler *handler = NULL;
131
132 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
133 handler = ext2_xattr_handler_map[name_index];
134 return handler;
135}
136
137static bool
138ext2_xattr_header_valid(struct ext2_xattr_header *header)
139{
140 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
141 header->h_blocks != cpu_to_le32(1))
142 return false;
143
144 return true;
145}
146
147static bool
148ext2_xattr_entry_valid(struct ext2_xattr_entry *entry,
149 char *end, size_t end_offs)
150{
151 struct ext2_xattr_entry *next;
152 size_t size;
153
154 next = EXT2_XATTR_NEXT(entry);
155 if ((char *)next >= end)
156 return false;
157
158 if (entry->e_value_block != 0)
159 return false;
160
161 size = le32_to_cpu(entry->e_value_size);
162 if (size > end_offs ||
163 le16_to_cpu(entry->e_value_offs) + size > end_offs)
164 return false;
165
166 return true;
167}
168
169static int
170ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name,
171 struct ext2_xattr_entry *entry)
172{
173 int cmp;
174
175 cmp = name_index - entry->e_name_index;
176 if (!cmp)
177 cmp = name_len - entry->e_name_len;
178 if (!cmp)
179 cmp = memcmp(name, entry->e_name, name_len);
180
181 return cmp;
182}
183
184/*
185 * ext2_xattr_get()
186 *
187 * Copy an extended attribute into the buffer
188 * provided, or compute the buffer size required.
189 * Buffer is NULL to compute the size of the buffer required.
190 *
191 * Returns a negative error number on failure, or the number of bytes
192 * used / required on success.
193 */
194int
195ext2_xattr_get(struct inode *inode, int name_index, const char *name,
196 void *buffer, size_t buffer_size)
197{
198 struct buffer_head *bh = NULL;
199 struct ext2_xattr_entry *entry;
200 size_t name_len, size;
201 char *end;
202 int error, not_found;
203 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
204
205 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
206 name_index, name, buffer, (long)buffer_size);
207
208 if (name == NULL)
209 return -EINVAL;
210 name_len = strlen(name);
211 if (name_len > 255)
212 return -ERANGE;
213
214 down_read(&EXT2_I(inode)->xattr_sem);
215 error = -ENODATA;
216 if (!EXT2_I(inode)->i_file_acl)
217 goto cleanup;
218 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
219 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
220 error = -EIO;
221 if (!bh)
222 goto cleanup;
223 ea_bdebug(bh, "b_count=%d, refcount=%d",
224 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
225 end = bh->b_data + bh->b_size;
226 if (!ext2_xattr_header_valid(HDR(bh))) {
227bad_block:
228 ext2_error(inode->i_sb, "ext2_xattr_get",
229 "inode %ld: bad block %d", inode->i_ino,
230 EXT2_I(inode)->i_file_acl);
231 error = -EIO;
232 goto cleanup;
233 }
234
235 /* find named attribute */
236 entry = FIRST_ENTRY(bh);
237 while (!IS_LAST_ENTRY(entry)) {
238 if (!ext2_xattr_entry_valid(entry, end,
239 inode->i_sb->s_blocksize))
240 goto bad_block;
241
242 not_found = ext2_xattr_cmp_entry(name_index, name_len, name,
243 entry);
244 if (!not_found)
245 goto found;
246 if (not_found < 0)
247 break;
248
249 entry = EXT2_XATTR_NEXT(entry);
250 }
251 if (ext2_xattr_cache_insert(ea_block_cache, bh))
252 ea_idebug(inode, "cache insert failed");
253 error = -ENODATA;
254 goto cleanup;
255found:
256 size = le32_to_cpu(entry->e_value_size);
257 if (ext2_xattr_cache_insert(ea_block_cache, bh))
258 ea_idebug(inode, "cache insert failed");
259 if (buffer) {
260 error = -ERANGE;
261 if (size > buffer_size)
262 goto cleanup;
263 /* return value of attribute */
264 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
265 size);
266 }
267 error = size;
268
269cleanup:
270 brelse(bh);
271 up_read(&EXT2_I(inode)->xattr_sem);
272
273 return error;
274}
275
276/*
277 * ext2_xattr_list()
278 *
279 * Copy a list of attribute names into the buffer
280 * provided, or compute the buffer size required.
281 * Buffer is NULL to compute the size of the buffer required.
282 *
283 * Returns a negative error number on failure, or the number of bytes
284 * used / required on success.
285 */
286static int
287ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
288{
289 struct inode *inode = d_inode(dentry);
290 struct buffer_head *bh = NULL;
291 struct ext2_xattr_entry *entry;
292 char *end;
293 size_t rest = buffer_size;
294 int error;
295 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
296
297 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
298 buffer, (long)buffer_size);
299
300 down_read(&EXT2_I(inode)->xattr_sem);
301 error = 0;
302 if (!EXT2_I(inode)->i_file_acl)
303 goto cleanup;
304 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
305 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
306 error = -EIO;
307 if (!bh)
308 goto cleanup;
309 ea_bdebug(bh, "b_count=%d, refcount=%d",
310 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
311 end = bh->b_data + bh->b_size;
312 if (!ext2_xattr_header_valid(HDR(bh))) {
313bad_block:
314 ext2_error(inode->i_sb, "ext2_xattr_list",
315 "inode %ld: bad block %d", inode->i_ino,
316 EXT2_I(inode)->i_file_acl);
317 error = -EIO;
318 goto cleanup;
319 }
320
321 /* check the on-disk data structure */
322 entry = FIRST_ENTRY(bh);
323 while (!IS_LAST_ENTRY(entry)) {
324 if (!ext2_xattr_entry_valid(entry, end,
325 inode->i_sb->s_blocksize))
326 goto bad_block;
327 entry = EXT2_XATTR_NEXT(entry);
328 }
329 if (ext2_xattr_cache_insert(ea_block_cache, bh))
330 ea_idebug(inode, "cache insert failed");
331
332 /* list the attribute names */
333 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
334 entry = EXT2_XATTR_NEXT(entry)) {
335 const struct xattr_handler *handler =
336 ext2_xattr_handler(entry->e_name_index);
337
338 if (handler && (!handler->list || handler->list(dentry))) {
339 const char *prefix = handler->prefix ?: handler->name;
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 down_write(&EXT2_I(inode)->xattr_sem);
440 if (EXT2_I(inode)->i_file_acl) {
441 /* The inode already has an extended attribute block. */
442 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
443 error = -EIO;
444 if (!bh)
445 goto cleanup;
446 ea_bdebug(bh, "b_count=%d, refcount=%d",
447 atomic_read(&(bh->b_count)),
448 le32_to_cpu(HDR(bh)->h_refcount));
449 header = HDR(bh);
450 end = bh->b_data + bh->b_size;
451 if (!ext2_xattr_header_valid(header)) {
452bad_block:
453 ext2_error(sb, "ext2_xattr_set",
454 "inode %ld: bad block %d", inode->i_ino,
455 EXT2_I(inode)->i_file_acl);
456 error = -EIO;
457 goto cleanup;
458 }
459 /*
460 * Find the named attribute. If not found, 'here' will point
461 * to entry where the new attribute should be inserted to
462 * maintain sorting.
463 */
464 last = FIRST_ENTRY(bh);
465 while (!IS_LAST_ENTRY(last)) {
466 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize))
467 goto bad_block;
468 if (last->e_value_size) {
469 size_t offs = le16_to_cpu(last->e_value_offs);
470 if (offs < min_offs)
471 min_offs = offs;
472 }
473 if (not_found > 0) {
474 not_found = ext2_xattr_cmp_entry(name_index,
475 name_len,
476 name, last);
477 if (not_found <= 0)
478 here = last;
479 }
480 last = EXT2_XATTR_NEXT(last);
481 }
482 if (not_found > 0)
483 here = last;
484
485 /* Check whether we have enough space left. */
486 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
487 } else {
488 /* We will use a new extended attribute block. */
489 free = sb->s_blocksize -
490 sizeof(struct ext2_xattr_header) - sizeof(__u32);
491 }
492
493 if (not_found) {
494 /* Request to remove a nonexistent attribute? */
495 error = -ENODATA;
496 if (flags & XATTR_REPLACE)
497 goto cleanup;
498 error = 0;
499 if (value == NULL)
500 goto cleanup;
501 } else {
502 /* Request to create an existing attribute? */
503 error = -EEXIST;
504 if (flags & XATTR_CREATE)
505 goto cleanup;
506 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size));
507 free += EXT2_XATTR_LEN(name_len);
508 }
509 error = -ENOSPC;
510 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
511 goto cleanup;
512
513 /* Here we know that we can set the new attribute. */
514
515 if (header) {
516 /* assert(header == HDR(bh)); */
517 lock_buffer(bh);
518 if (header->h_refcount == cpu_to_le32(1)) {
519 __u32 hash = le32_to_cpu(header->h_hash);
520
521 ea_bdebug(bh, "modifying in-place");
522 /*
523 * This must happen under buffer lock for
524 * ext2_xattr_set2() to reliably detect modified block
525 */
526 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash,
527 bh->b_blocknr);
528
529 /* keep the buffer locked while modifying it. */
530 } else {
531 int offset;
532
533 unlock_buffer(bh);
534 ea_bdebug(bh, "cloning");
535 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL);
536 error = -ENOMEM;
537 if (header == NULL)
538 goto cleanup;
539 header->h_refcount = cpu_to_le32(1);
540
541 offset = (char *)here - bh->b_data;
542 here = ENTRY((char *)header + offset);
543 offset = (char *)last - bh->b_data;
544 last = ENTRY((char *)header + offset);
545 }
546 } else {
547 /* Allocate a buffer where we construct the new block. */
548 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
549 error = -ENOMEM;
550 if (header == NULL)
551 goto cleanup;
552 end = (char *)header + sb->s_blocksize;
553 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
554 header->h_blocks = header->h_refcount = cpu_to_le32(1);
555 last = here = ENTRY(header+1);
556 }
557
558 /* Iff we are modifying the block in-place, bh is locked here. */
559
560 if (not_found) {
561 /* Insert the new name. */
562 size_t size = EXT2_XATTR_LEN(name_len);
563 size_t rest = (char *)last - (char *)here;
564 memmove((char *)here + size, here, rest);
565 memset(here, 0, size);
566 here->e_name_index = name_index;
567 here->e_name_len = name_len;
568 memcpy(here->e_name, name, name_len);
569 } else {
570 if (here->e_value_size) {
571 char *first_val = (char *)header + min_offs;
572 size_t offs = le16_to_cpu(here->e_value_offs);
573 char *val = (char *)header + offs;
574 size_t size = EXT2_XATTR_SIZE(
575 le32_to_cpu(here->e_value_size));
576
577 if (size == EXT2_XATTR_SIZE(value_len)) {
578 /* The old and the new value have the same
579 size. Just replace. */
580 here->e_value_size = cpu_to_le32(value_len);
581 memset(val + size - EXT2_XATTR_PAD, 0,
582 EXT2_XATTR_PAD); /* Clear pad bytes. */
583 memcpy(val, value, value_len);
584 goto skip_replace;
585 }
586
587 /* Remove the old value. */
588 memmove(first_val + size, first_val, val - first_val);
589 memset(first_val, 0, size);
590 here->e_value_offs = 0;
591 min_offs += size;
592
593 /* Adjust all value offsets. */
594 last = ENTRY(header+1);
595 while (!IS_LAST_ENTRY(last)) {
596 size_t o = le16_to_cpu(last->e_value_offs);
597 if (o < offs)
598 last->e_value_offs =
599 cpu_to_le16(o + size);
600 last = EXT2_XATTR_NEXT(last);
601 }
602 }
603 if (value == NULL) {
604 /* Remove the old name. */
605 size_t size = EXT2_XATTR_LEN(name_len);
606 last = ENTRY((char *)last - size);
607 memmove(here, (char*)here + size,
608 (char*)last - (char*)here);
609 memset(last, 0, size);
610 }
611 }
612
613 if (value != NULL) {
614 /* Insert the new value. */
615 here->e_value_size = cpu_to_le32(value_len);
616 if (value_len) {
617 size_t size = EXT2_XATTR_SIZE(value_len);
618 char *val = (char *)header + min_offs - size;
619 here->e_value_offs =
620 cpu_to_le16((char *)val - (char *)header);
621 memset(val + size - EXT2_XATTR_PAD, 0,
622 EXT2_XATTR_PAD); /* Clear the pad bytes. */
623 memcpy(val, value, value_len);
624 }
625 }
626
627skip_replace:
628 if (IS_LAST_ENTRY(ENTRY(header+1))) {
629 /* This block is now empty. */
630 if (bh && header == HDR(bh))
631 unlock_buffer(bh); /* we were modifying in-place. */
632 error = ext2_xattr_set2(inode, bh, NULL);
633 } else {
634 ext2_xattr_rehash(header, here);
635 if (bh && header == HDR(bh))
636 unlock_buffer(bh); /* we were modifying in-place. */
637 error = ext2_xattr_set2(inode, bh, header);
638 }
639
640cleanup:
641 if (!(bh && header == HDR(bh)))
642 kfree(header);
643 brelse(bh);
644 up_write(&EXT2_I(inode)->xattr_sem);
645
646 return error;
647}
648
649/*
650 * Second half of ext2_xattr_set(): Update the file system.
651 */
652static int
653ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
654 struct ext2_xattr_header *header)
655{
656 struct super_block *sb = inode->i_sb;
657 struct buffer_head *new_bh = NULL;
658 int error;
659 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
660
661 if (header) {
662 new_bh = ext2_xattr_cache_find(inode, header);
663 if (new_bh) {
664 /* We found an identical block in the cache. */
665 if (new_bh == old_bh) {
666 ea_bdebug(new_bh, "keeping this block");
667 } else {
668 /* The old block is released after updating
669 the inode. */
670 ea_bdebug(new_bh, "reusing block");
671
672 error = dquot_alloc_block(inode, 1);
673 if (error) {
674 unlock_buffer(new_bh);
675 goto cleanup;
676 }
677 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
678 ea_bdebug(new_bh, "refcount now=%d",
679 le32_to_cpu(HDR(new_bh)->h_refcount));
680 }
681 unlock_buffer(new_bh);
682 } else if (old_bh && header == HDR(old_bh)) {
683 /* Keep this block. No need to lock the block as we
684 don't need to change the reference count. */
685 new_bh = old_bh;
686 get_bh(new_bh);
687 ext2_xattr_cache_insert(ea_block_cache, new_bh);
688 } else {
689 /* We need to allocate a new block */
690 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
691 EXT2_I(inode)->i_block_group);
692 int block = ext2_new_block(inode, goal, &error);
693 if (error)
694 goto cleanup;
695 ea_idebug(inode, "creating block %d", block);
696
697 new_bh = sb_getblk(sb, block);
698 if (unlikely(!new_bh)) {
699 ext2_free_blocks(inode, block, 1);
700 mark_inode_dirty(inode);
701 error = -ENOMEM;
702 goto cleanup;
703 }
704 lock_buffer(new_bh);
705 memcpy(new_bh->b_data, header, new_bh->b_size);
706 set_buffer_uptodate(new_bh);
707 unlock_buffer(new_bh);
708 ext2_xattr_cache_insert(ea_block_cache, new_bh);
709
710 ext2_xattr_update_super_block(sb);
711 }
712 mark_buffer_dirty(new_bh);
713 if (IS_SYNC(inode)) {
714 sync_dirty_buffer(new_bh);
715 error = -EIO;
716 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
717 goto cleanup;
718 }
719 }
720
721 /* Update the inode. */
722 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
723 inode->i_ctime = current_time(inode);
724 if (IS_SYNC(inode)) {
725 error = sync_inode_metadata(inode, 1);
726 /* In case sync failed due to ENOSPC the inode was actually
727 * written (only some dirty data were not) so we just proceed
728 * as if nothing happened and cleanup the unused block */
729 if (error && error != -ENOSPC) {
730 if (new_bh && new_bh != old_bh) {
731 dquot_free_block_nodirty(inode, 1);
732 mark_inode_dirty(inode);
733 }
734 goto cleanup;
735 }
736 } else
737 mark_inode_dirty(inode);
738
739 error = 0;
740 if (old_bh && old_bh != new_bh) {
741 /*
742 * If there was an old block and we are no longer using it,
743 * release the old block.
744 */
745 lock_buffer(old_bh);
746 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
747 __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash);
748
749 /*
750 * This must happen under buffer lock for
751 * ext2_xattr_set2() to reliably detect freed block
752 */
753 mb_cache_entry_delete(ea_block_cache, hash,
754 old_bh->b_blocknr);
755 /* Free the old block. */
756 ea_bdebug(old_bh, "freeing");
757 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
758 mark_inode_dirty(inode);
759 /* We let our caller release old_bh, so we
760 * need to duplicate the buffer before. */
761 get_bh(old_bh);
762 bforget(old_bh);
763 } else {
764 /* Decrement the refcount only. */
765 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
766 dquot_free_block_nodirty(inode, 1);
767 mark_inode_dirty(inode);
768 mark_buffer_dirty(old_bh);
769 ea_bdebug(old_bh, "refcount now=%d",
770 le32_to_cpu(HDR(old_bh)->h_refcount));
771 }
772 unlock_buffer(old_bh);
773 }
774
775cleanup:
776 brelse(new_bh);
777
778 return error;
779}
780
781/*
782 * ext2_xattr_delete_inode()
783 *
784 * Free extended attribute resources associated with this inode. This
785 * is called immediately before an inode is freed.
786 */
787void
788ext2_xattr_delete_inode(struct inode *inode)
789{
790 struct buffer_head *bh = NULL;
791 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
792
793 down_write(&EXT2_I(inode)->xattr_sem);
794 if (!EXT2_I(inode)->i_file_acl)
795 goto cleanup;
796
797 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) {
798 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
799 "inode %ld: xattr block %d is out of data blocks range",
800 inode->i_ino, EXT2_I(inode)->i_file_acl);
801 goto cleanup;
802 }
803
804 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
805 if (!bh) {
806 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
807 "inode %ld: block %d read error", inode->i_ino,
808 EXT2_I(inode)->i_file_acl);
809 goto cleanup;
810 }
811 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
812 if (!ext2_xattr_header_valid(HDR(bh))) {
813 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
814 "inode %ld: bad block %d", inode->i_ino,
815 EXT2_I(inode)->i_file_acl);
816 goto cleanup;
817 }
818 lock_buffer(bh);
819 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
820 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
821
822 /*
823 * This must happen under buffer lock for ext2_xattr_set2() to
824 * reliably detect freed block
825 */
826 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash,
827 bh->b_blocknr);
828 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
829 get_bh(bh);
830 bforget(bh);
831 unlock_buffer(bh);
832 } else {
833 le32_add_cpu(&HDR(bh)->h_refcount, -1);
834 ea_bdebug(bh, "refcount now=%d",
835 le32_to_cpu(HDR(bh)->h_refcount));
836 unlock_buffer(bh);
837 mark_buffer_dirty(bh);
838 if (IS_SYNC(inode))
839 sync_dirty_buffer(bh);
840 dquot_free_block_nodirty(inode, 1);
841 }
842 EXT2_I(inode)->i_file_acl = 0;
843
844cleanup:
845 brelse(bh);
846 up_write(&EXT2_I(inode)->xattr_sem);
847}
848
849/*
850 * ext2_xattr_cache_insert()
851 *
852 * Create a new entry in the extended attribute cache, and insert
853 * it unless such an entry is already in the cache.
854 *
855 * Returns 0, or a negative error number on failure.
856 */
857static int
858ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)
859{
860 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
861 int error;
862
863 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr,
864 true);
865 if (error) {
866 if (error == -EBUSY) {
867 ea_bdebug(bh, "already in cache (%d cache entries)",
868 atomic_read(&ext2_xattr_cache->c_entry_count));
869 error = 0;
870 }
871 } else
872 ea_bdebug(bh, "inserting [%x]", (int)hash);
873 return error;
874}
875
876/*
877 * ext2_xattr_cmp()
878 *
879 * Compare two extended attribute blocks for equality.
880 *
881 * Returns 0 if the blocks are equal, 1 if they differ, and
882 * a negative error number on errors.
883 */
884static int
885ext2_xattr_cmp(struct ext2_xattr_header *header1,
886 struct ext2_xattr_header *header2)
887{
888 struct ext2_xattr_entry *entry1, *entry2;
889
890 entry1 = ENTRY(header1+1);
891 entry2 = ENTRY(header2+1);
892 while (!IS_LAST_ENTRY(entry1)) {
893 if (IS_LAST_ENTRY(entry2))
894 return 1;
895 if (entry1->e_hash != entry2->e_hash ||
896 entry1->e_name_index != entry2->e_name_index ||
897 entry1->e_name_len != entry2->e_name_len ||
898 entry1->e_value_size != entry2->e_value_size ||
899 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
900 return 1;
901 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
902 return -EIO;
903 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
904 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
905 le32_to_cpu(entry1->e_value_size)))
906 return 1;
907
908 entry1 = EXT2_XATTR_NEXT(entry1);
909 entry2 = EXT2_XATTR_NEXT(entry2);
910 }
911 if (!IS_LAST_ENTRY(entry2))
912 return 1;
913 return 0;
914}
915
916/*
917 * ext2_xattr_cache_find()
918 *
919 * Find an identical extended attribute block.
920 *
921 * Returns a locked buffer head to the block found, or NULL if such
922 * a block was not found or an error occurred.
923 */
924static struct buffer_head *
925ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
926{
927 __u32 hash = le32_to_cpu(header->h_hash);
928 struct mb_cache_entry *ce;
929 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
930
931 if (!header->h_hash)
932 return NULL; /* never share */
933 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
934again:
935 ce = mb_cache_entry_find_first(ea_block_cache, hash);
936 while (ce) {
937 struct buffer_head *bh;
938
939 bh = sb_bread(inode->i_sb, ce->e_value);
940 if (!bh) {
941 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
942 "inode %ld: block %ld read error",
943 inode->i_ino, (unsigned long) ce->e_value);
944 } else {
945 lock_buffer(bh);
946 /*
947 * We have to be careful about races with freeing or
948 * rehashing of xattr block. Once we hold buffer lock
949 * xattr block's state is stable so we can check
950 * whether the block got freed / rehashed or not.
951 * Since we unhash mbcache entry under buffer lock when
952 * freeing / rehashing xattr block, checking whether
953 * entry is still hashed is reliable.
954 */
955 if (hlist_bl_unhashed(&ce->e_hash_list)) {
956 mb_cache_entry_put(ea_block_cache, ce);
957 unlock_buffer(bh);
958 brelse(bh);
959 goto again;
960 } else if (le32_to_cpu(HDR(bh)->h_refcount) >
961 EXT2_XATTR_REFCOUNT_MAX) {
962 ea_idebug(inode, "block %ld refcount %d>%d",
963 (unsigned long) ce->e_value,
964 le32_to_cpu(HDR(bh)->h_refcount),
965 EXT2_XATTR_REFCOUNT_MAX);
966 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
967 ea_bdebug(bh, "b_count=%d",
968 atomic_read(&(bh->b_count)));
969 mb_cache_entry_touch(ea_block_cache, ce);
970 mb_cache_entry_put(ea_block_cache, ce);
971 return bh;
972 }
973 unlock_buffer(bh);
974 brelse(bh);
975 }
976 ce = mb_cache_entry_find_next(ea_block_cache, ce);
977 }
978 return NULL;
979}
980
981#define NAME_HASH_SHIFT 5
982#define VALUE_HASH_SHIFT 16
983
984/*
985 * ext2_xattr_hash_entry()
986 *
987 * Compute the hash of an extended attribute.
988 */
989static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
990 struct ext2_xattr_entry *entry)
991{
992 __u32 hash = 0;
993 char *name = entry->e_name;
994 int n;
995
996 for (n=0; n < entry->e_name_len; n++) {
997 hash = (hash << NAME_HASH_SHIFT) ^
998 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
999 *name++;
1000 }
1001
1002 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1003 __le32 *value = (__le32 *)((char *)header +
1004 le16_to_cpu(entry->e_value_offs));
1005 for (n = (le32_to_cpu(entry->e_value_size) +
1006 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
1007 hash = (hash << VALUE_HASH_SHIFT) ^
1008 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1009 le32_to_cpu(*value++);
1010 }
1011 }
1012 entry->e_hash = cpu_to_le32(hash);
1013}
1014
1015#undef NAME_HASH_SHIFT
1016#undef VALUE_HASH_SHIFT
1017
1018#define BLOCK_HASH_SHIFT 16
1019
1020/*
1021 * ext2_xattr_rehash()
1022 *
1023 * Re-compute the extended attribute hash value after an entry has changed.
1024 */
1025static void ext2_xattr_rehash(struct ext2_xattr_header *header,
1026 struct ext2_xattr_entry *entry)
1027{
1028 struct ext2_xattr_entry *here;
1029 __u32 hash = 0;
1030
1031 ext2_xattr_hash_entry(header, entry);
1032 here = ENTRY(header+1);
1033 while (!IS_LAST_ENTRY(here)) {
1034 if (!here->e_hash) {
1035 /* Block is not shared if an entry's hash value == 0 */
1036 hash = 0;
1037 break;
1038 }
1039 hash = (hash << BLOCK_HASH_SHIFT) ^
1040 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1041 le32_to_cpu(here->e_hash);
1042 here = EXT2_XATTR_NEXT(here);
1043 }
1044 header->h_hash = cpu_to_le32(hash);
1045}
1046
1047#undef BLOCK_HASH_SHIFT
1048
1049#define HASH_BUCKET_BITS 10
1050
1051struct mb_cache *ext2_xattr_create_cache(void)
1052{
1053 return mb_cache_create(HASH_BUCKET_BITS);
1054}
1055
1056void ext2_xattr_destroy_cache(struct mb_cache *cache)
1057{
1058 if (cache)
1059 mb_cache_destroy(cache);
1060}
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/init.h>
58#include <linux/slab.h>
59#include <linux/mbcache.h>
60#include <linux/quotaops.h>
61#include <linux/rwsem.h>
62#include <linux/security.h>
63#include "ext2.h"
64#include "xattr.h"
65#include "acl.h"
66
67#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
68#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
69#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
70#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
71
72#ifdef EXT2_XATTR_DEBUG
73# define ea_idebug(inode, f...) do { \
74 printk(KERN_DEBUG "inode %s:%ld: ", \
75 inode->i_sb->s_id, inode->i_ino); \
76 printk(f); \
77 printk("\n"); \
78 } while (0)
79# define ea_bdebug(bh, f...) do { \
80 printk(KERN_DEBUG "block %pg:%lu: ", \
81 bh->b_bdev, (unsigned long) bh->b_blocknr); \
82 printk(f); \
83 printk("\n"); \
84 } while (0)
85#else
86# define ea_idebug(f...)
87# define ea_bdebug(f...)
88#endif
89
90static int ext2_xattr_set2(struct inode *, struct buffer_head *,
91 struct ext2_xattr_header *);
92
93static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
94static struct buffer_head *ext2_xattr_cache_find(struct inode *,
95 struct ext2_xattr_header *);
96static void ext2_xattr_rehash(struct ext2_xattr_header *,
97 struct ext2_xattr_entry *);
98
99static const struct xattr_handler *ext2_xattr_handler_map[] = {
100 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
101#ifdef CONFIG_EXT2_FS_POSIX_ACL
102 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler,
103 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
104#endif
105 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
106#ifdef CONFIG_EXT2_FS_SECURITY
107 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
108#endif
109};
110
111const struct xattr_handler *ext2_xattr_handlers[] = {
112 &ext2_xattr_user_handler,
113 &ext2_xattr_trusted_handler,
114#ifdef CONFIG_EXT2_FS_POSIX_ACL
115 &posix_acl_access_xattr_handler,
116 &posix_acl_default_xattr_handler,
117#endif
118#ifdef CONFIG_EXT2_FS_SECURITY
119 &ext2_xattr_security_handler,
120#endif
121 NULL
122};
123
124static inline const struct xattr_handler *
125ext2_xattr_handler(int name_index)
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 return handler;
132}
133
134/*
135 * ext2_xattr_get()
136 *
137 * Copy an extended attribute into the buffer
138 * provided, or compute the buffer size required.
139 * Buffer is NULL to compute the size of the buffer required.
140 *
141 * Returns a negative error number on failure, or the number of bytes
142 * used / required on success.
143 */
144int
145ext2_xattr_get(struct inode *inode, int name_index, const char *name,
146 void *buffer, size_t buffer_size)
147{
148 struct buffer_head *bh = NULL;
149 struct ext2_xattr_entry *entry;
150 size_t name_len, size;
151 char *end;
152 int error;
153 struct mb_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache;
154
155 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
156 name_index, name, buffer, (long)buffer_size);
157
158 if (name == NULL)
159 return -EINVAL;
160 name_len = strlen(name);
161 if (name_len > 255)
162 return -ERANGE;
163
164 down_read(&EXT2_I(inode)->xattr_sem);
165 error = -ENODATA;
166 if (!EXT2_I(inode)->i_file_acl)
167 goto cleanup;
168 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
169 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
170 error = -EIO;
171 if (!bh)
172 goto cleanup;
173 ea_bdebug(bh, "b_count=%d, refcount=%d",
174 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
175 end = bh->b_data + bh->b_size;
176 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
177 HDR(bh)->h_blocks != cpu_to_le32(1)) {
178bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
179 "inode %ld: bad block %d", inode->i_ino,
180 EXT2_I(inode)->i_file_acl);
181 error = -EIO;
182 goto cleanup;
183 }
184
185 /* find named attribute */
186 entry = FIRST_ENTRY(bh);
187 while (!IS_LAST_ENTRY(entry)) {
188 struct ext2_xattr_entry *next =
189 EXT2_XATTR_NEXT(entry);
190 if ((char *)next >= end)
191 goto bad_block;
192 if (name_index == entry->e_name_index &&
193 name_len == entry->e_name_len &&
194 memcmp(name, entry->e_name, name_len) == 0)
195 goto found;
196 entry = next;
197 }
198 if (ext2_xattr_cache_insert(ext2_mb_cache, bh))
199 ea_idebug(inode, "cache insert failed");
200 error = -ENODATA;
201 goto cleanup;
202found:
203 /* check the buffer size */
204 if (entry->e_value_block != 0)
205 goto bad_block;
206 size = le32_to_cpu(entry->e_value_size);
207 if (size > inode->i_sb->s_blocksize ||
208 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
209 goto bad_block;
210
211 if (ext2_xattr_cache_insert(ext2_mb_cache, bh))
212 ea_idebug(inode, "cache insert failed");
213 if (buffer) {
214 error = -ERANGE;
215 if (size > buffer_size)
216 goto cleanup;
217 /* return value of attribute */
218 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
219 size);
220 }
221 error = size;
222
223cleanup:
224 brelse(bh);
225 up_read(&EXT2_I(inode)->xattr_sem);
226
227 return error;
228}
229
230/*
231 * ext2_xattr_list()
232 *
233 * Copy a list of attribute names into the buffer
234 * provided, or compute the buffer size required.
235 * Buffer is NULL to compute the size of the buffer required.
236 *
237 * Returns a negative error number on failure, or the number of bytes
238 * used / required on success.
239 */
240static int
241ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
242{
243 struct inode *inode = d_inode(dentry);
244 struct buffer_head *bh = NULL;
245 struct ext2_xattr_entry *entry;
246 char *end;
247 size_t rest = buffer_size;
248 int error;
249 struct mb_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache;
250
251 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
252 buffer, (long)buffer_size);
253
254 down_read(&EXT2_I(inode)->xattr_sem);
255 error = 0;
256 if (!EXT2_I(inode)->i_file_acl)
257 goto cleanup;
258 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
259 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
260 error = -EIO;
261 if (!bh)
262 goto cleanup;
263 ea_bdebug(bh, "b_count=%d, refcount=%d",
264 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
265 end = bh->b_data + bh->b_size;
266 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
267 HDR(bh)->h_blocks != cpu_to_le32(1)) {
268bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
269 "inode %ld: bad block %d", inode->i_ino,
270 EXT2_I(inode)->i_file_acl);
271 error = -EIO;
272 goto cleanup;
273 }
274
275 /* check the on-disk data structure */
276 entry = FIRST_ENTRY(bh);
277 while (!IS_LAST_ENTRY(entry)) {
278 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
279
280 if ((char *)next >= end)
281 goto bad_block;
282 entry = next;
283 }
284 if (ext2_xattr_cache_insert(ext2_mb_cache, bh))
285 ea_idebug(inode, "cache insert failed");
286
287 /* list the attribute names */
288 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
289 entry = EXT2_XATTR_NEXT(entry)) {
290 const struct xattr_handler *handler =
291 ext2_xattr_handler(entry->e_name_index);
292
293 if (handler && (!handler->list || handler->list(dentry))) {
294 const char *prefix = handler->prefix ?: handler->name;
295 size_t prefix_len = strlen(prefix);
296 size_t size = prefix_len + entry->e_name_len + 1;
297
298 if (buffer) {
299 if (size > rest) {
300 error = -ERANGE;
301 goto cleanup;
302 }
303 memcpy(buffer, prefix, prefix_len);
304 buffer += prefix_len;
305 memcpy(buffer, entry->e_name, entry->e_name_len);
306 buffer += entry->e_name_len;
307 *buffer++ = 0;
308 }
309 rest -= size;
310 }
311 }
312 error = buffer_size - rest; /* total size */
313
314cleanup:
315 brelse(bh);
316 up_read(&EXT2_I(inode)->xattr_sem);
317
318 return error;
319}
320
321/*
322 * Inode operation listxattr()
323 *
324 * d_inode(dentry)->i_mutex: don't care
325 */
326ssize_t
327ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
328{
329 return ext2_xattr_list(dentry, buffer, size);
330}
331
332/*
333 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
334 * not set, set it.
335 */
336static void ext2_xattr_update_super_block(struct super_block *sb)
337{
338 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
339 return;
340
341 spin_lock(&EXT2_SB(sb)->s_lock);
342 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
343 spin_unlock(&EXT2_SB(sb)->s_lock);
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 /* assert(header == HDR(bh)); */
487 lock_buffer(bh);
488 if (header->h_refcount == cpu_to_le32(1)) {
489 __u32 hash = le32_to_cpu(header->h_hash);
490
491 ea_bdebug(bh, "modifying in-place");
492 /*
493 * This must happen under buffer lock for
494 * ext2_xattr_set2() to reliably detect modified block
495 */
496 mb_cache_entry_delete_block(EXT2_SB(sb)->s_mb_cache,
497 hash, bh->b_blocknr);
498
499 /* keep the buffer locked while modifying it. */
500 } else {
501 int offset;
502
503 unlock_buffer(bh);
504 ea_bdebug(bh, "cloning");
505 header = kmalloc(bh->b_size, GFP_KERNEL);
506 error = -ENOMEM;
507 if (header == NULL)
508 goto cleanup;
509 memcpy(header, HDR(bh), bh->b_size);
510 header->h_refcount = cpu_to_le32(1);
511
512 offset = (char *)here - bh->b_data;
513 here = ENTRY((char *)header + offset);
514 offset = (char *)last - bh->b_data;
515 last = ENTRY((char *)header + offset);
516 }
517 } else {
518 /* Allocate a buffer where we construct the new block. */
519 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
520 error = -ENOMEM;
521 if (header == NULL)
522 goto cleanup;
523 end = (char *)header + sb->s_blocksize;
524 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
525 header->h_blocks = header->h_refcount = cpu_to_le32(1);
526 last = here = ENTRY(header+1);
527 }
528
529 /* Iff we are modifying the block in-place, bh is locked here. */
530
531 if (not_found) {
532 /* Insert the new name. */
533 size_t size = EXT2_XATTR_LEN(name_len);
534 size_t rest = (char *)last - (char *)here;
535 memmove((char *)here + size, here, rest);
536 memset(here, 0, size);
537 here->e_name_index = name_index;
538 here->e_name_len = name_len;
539 memcpy(here->e_name, name, name_len);
540 } else {
541 if (!here->e_value_block && here->e_value_size) {
542 char *first_val = (char *)header + min_offs;
543 size_t offs = le16_to_cpu(here->e_value_offs);
544 char *val = (char *)header + offs;
545 size_t size = EXT2_XATTR_SIZE(
546 le32_to_cpu(here->e_value_size));
547
548 if (size == EXT2_XATTR_SIZE(value_len)) {
549 /* The old and the new value have the same
550 size. Just replace. */
551 here->e_value_size = cpu_to_le32(value_len);
552 memset(val + size - EXT2_XATTR_PAD, 0,
553 EXT2_XATTR_PAD); /* Clear pad bytes. */
554 memcpy(val, value, value_len);
555 goto skip_replace;
556 }
557
558 /* Remove the old value. */
559 memmove(first_val + size, first_val, val - first_val);
560 memset(first_val, 0, size);
561 here->e_value_offs = 0;
562 min_offs += size;
563
564 /* Adjust all value offsets. */
565 last = ENTRY(header+1);
566 while (!IS_LAST_ENTRY(last)) {
567 size_t o = le16_to_cpu(last->e_value_offs);
568 if (!last->e_value_block && o < offs)
569 last->e_value_offs =
570 cpu_to_le16(o + size);
571 last = EXT2_XATTR_NEXT(last);
572 }
573 }
574 if (value == NULL) {
575 /* Remove the old name. */
576 size_t size = EXT2_XATTR_LEN(name_len);
577 last = ENTRY((char *)last - size);
578 memmove(here, (char*)here + size,
579 (char*)last - (char*)here);
580 memset(last, 0, size);
581 }
582 }
583
584 if (value != NULL) {
585 /* Insert the new value. */
586 here->e_value_size = cpu_to_le32(value_len);
587 if (value_len) {
588 size_t size = EXT2_XATTR_SIZE(value_len);
589 char *val = (char *)header + min_offs - size;
590 here->e_value_offs =
591 cpu_to_le16((char *)val - (char *)header);
592 memset(val + size - EXT2_XATTR_PAD, 0,
593 EXT2_XATTR_PAD); /* Clear the pad bytes. */
594 memcpy(val, value, value_len);
595 }
596 }
597
598skip_replace:
599 if (IS_LAST_ENTRY(ENTRY(header+1))) {
600 /* This block is now empty. */
601 if (bh && header == HDR(bh))
602 unlock_buffer(bh); /* we were modifying in-place. */
603 error = ext2_xattr_set2(inode, bh, NULL);
604 } else {
605 ext2_xattr_rehash(header, here);
606 if (bh && header == HDR(bh))
607 unlock_buffer(bh); /* we were modifying in-place. */
608 error = ext2_xattr_set2(inode, bh, header);
609 }
610
611cleanup:
612 brelse(bh);
613 if (!(bh && header == HDR(bh)))
614 kfree(header);
615 up_write(&EXT2_I(inode)->xattr_sem);
616
617 return error;
618}
619
620/*
621 * Second half of ext2_xattr_set(): Update the file system.
622 */
623static int
624ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
625 struct ext2_xattr_header *header)
626{
627 struct super_block *sb = inode->i_sb;
628 struct buffer_head *new_bh = NULL;
629 int error;
630 struct mb_cache *ext2_mb_cache = EXT2_SB(sb)->s_mb_cache;
631
632 if (header) {
633 new_bh = ext2_xattr_cache_find(inode, header);
634 if (new_bh) {
635 /* We found an identical block in the cache. */
636 if (new_bh == old_bh) {
637 ea_bdebug(new_bh, "keeping this block");
638 } else {
639 /* The old block is released after updating
640 the inode. */
641 ea_bdebug(new_bh, "reusing block");
642
643 error = dquot_alloc_block(inode, 1);
644 if (error) {
645 unlock_buffer(new_bh);
646 goto cleanup;
647 }
648 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
649 ea_bdebug(new_bh, "refcount now=%d",
650 le32_to_cpu(HDR(new_bh)->h_refcount));
651 }
652 unlock_buffer(new_bh);
653 } else if (old_bh && header == HDR(old_bh)) {
654 /* Keep this block. No need to lock the block as we
655 don't need to change the reference count. */
656 new_bh = old_bh;
657 get_bh(new_bh);
658 ext2_xattr_cache_insert(ext2_mb_cache, new_bh);
659 } else {
660 /* We need to allocate a new block */
661 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
662 EXT2_I(inode)->i_block_group);
663 int block = ext2_new_block(inode, goal, &error);
664 if (error)
665 goto cleanup;
666 ea_idebug(inode, "creating block %d", block);
667
668 new_bh = sb_getblk(sb, block);
669 if (unlikely(!new_bh)) {
670 ext2_free_blocks(inode, block, 1);
671 mark_inode_dirty(inode);
672 error = -ENOMEM;
673 goto cleanup;
674 }
675 lock_buffer(new_bh);
676 memcpy(new_bh->b_data, header, new_bh->b_size);
677 set_buffer_uptodate(new_bh);
678 unlock_buffer(new_bh);
679 ext2_xattr_cache_insert(ext2_mb_cache, new_bh);
680
681 ext2_xattr_update_super_block(sb);
682 }
683 mark_buffer_dirty(new_bh);
684 if (IS_SYNC(inode)) {
685 sync_dirty_buffer(new_bh);
686 error = -EIO;
687 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
688 goto cleanup;
689 }
690 }
691
692 /* Update the inode. */
693 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
694 inode->i_ctime = CURRENT_TIME_SEC;
695 if (IS_SYNC(inode)) {
696 error = sync_inode_metadata(inode, 1);
697 /* In case sync failed due to ENOSPC the inode was actually
698 * written (only some dirty data were not) so we just proceed
699 * as if nothing happened and cleanup the unused block */
700 if (error && error != -ENOSPC) {
701 if (new_bh && new_bh != old_bh) {
702 dquot_free_block_nodirty(inode, 1);
703 mark_inode_dirty(inode);
704 }
705 goto cleanup;
706 }
707 } else
708 mark_inode_dirty(inode);
709
710 error = 0;
711 if (old_bh && old_bh != new_bh) {
712 /*
713 * If there was an old block and we are no longer using it,
714 * release the old block.
715 */
716 lock_buffer(old_bh);
717 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
718 __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash);
719
720 /*
721 * This must happen under buffer lock for
722 * ext2_xattr_set2() to reliably detect freed block
723 */
724 mb_cache_entry_delete_block(ext2_mb_cache,
725 hash, old_bh->b_blocknr);
726 /* Free the old block. */
727 ea_bdebug(old_bh, "freeing");
728 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
729 mark_inode_dirty(inode);
730 /* We let our caller release old_bh, so we
731 * need to duplicate the buffer before. */
732 get_bh(old_bh);
733 bforget(old_bh);
734 } else {
735 /* Decrement the refcount only. */
736 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
737 dquot_free_block_nodirty(inode, 1);
738 mark_inode_dirty(inode);
739 mark_buffer_dirty(old_bh);
740 ea_bdebug(old_bh, "refcount now=%d",
741 le32_to_cpu(HDR(old_bh)->h_refcount));
742 }
743 unlock_buffer(old_bh);
744 }
745
746cleanup:
747 brelse(new_bh);
748
749 return error;
750}
751
752/*
753 * ext2_xattr_delete_inode()
754 *
755 * Free extended attribute resources associated with this inode. This
756 * is called immediately before an inode is freed.
757 */
758void
759ext2_xattr_delete_inode(struct inode *inode)
760{
761 struct buffer_head *bh = NULL;
762
763 down_write(&EXT2_I(inode)->xattr_sem);
764 if (!EXT2_I(inode)->i_file_acl)
765 goto cleanup;
766 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
767 if (!bh) {
768 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
769 "inode %ld: block %d read error", inode->i_ino,
770 EXT2_I(inode)->i_file_acl);
771 goto cleanup;
772 }
773 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
774 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
775 HDR(bh)->h_blocks != cpu_to_le32(1)) {
776 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
777 "inode %ld: bad block %d", inode->i_ino,
778 EXT2_I(inode)->i_file_acl);
779 goto cleanup;
780 }
781 lock_buffer(bh);
782 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
783 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
784
785 /*
786 * This must happen under buffer lock for ext2_xattr_set2() to
787 * reliably detect freed block
788 */
789 mb_cache_entry_delete_block(EXT2_SB(inode->i_sb)->s_mb_cache,
790 hash, bh->b_blocknr);
791 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
792 get_bh(bh);
793 bforget(bh);
794 unlock_buffer(bh);
795 } else {
796 le32_add_cpu(&HDR(bh)->h_refcount, -1);
797 ea_bdebug(bh, "refcount now=%d",
798 le32_to_cpu(HDR(bh)->h_refcount));
799 unlock_buffer(bh);
800 mark_buffer_dirty(bh);
801 if (IS_SYNC(inode))
802 sync_dirty_buffer(bh);
803 dquot_free_block_nodirty(inode, 1);
804 }
805 EXT2_I(inode)->i_file_acl = 0;
806
807cleanup:
808 brelse(bh);
809 up_write(&EXT2_I(inode)->xattr_sem);
810}
811
812/*
813 * ext2_xattr_cache_insert()
814 *
815 * Create a new entry in the extended attribute cache, and insert
816 * it unless such an entry is already in the cache.
817 *
818 * Returns 0, or a negative error number on failure.
819 */
820static int
821ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)
822{
823 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
824 int error;
825
826 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, 1);
827 if (error) {
828 if (error == -EBUSY) {
829 ea_bdebug(bh, "already in cache (%d cache entries)",
830 atomic_read(&ext2_xattr_cache->c_entry_count));
831 error = 0;
832 }
833 } else
834 ea_bdebug(bh, "inserting [%x]", (int)hash);
835 return error;
836}
837
838/*
839 * ext2_xattr_cmp()
840 *
841 * Compare two extended attribute blocks for equality.
842 *
843 * Returns 0 if the blocks are equal, 1 if they differ, and
844 * a negative error number on errors.
845 */
846static int
847ext2_xattr_cmp(struct ext2_xattr_header *header1,
848 struct ext2_xattr_header *header2)
849{
850 struct ext2_xattr_entry *entry1, *entry2;
851
852 entry1 = ENTRY(header1+1);
853 entry2 = ENTRY(header2+1);
854 while (!IS_LAST_ENTRY(entry1)) {
855 if (IS_LAST_ENTRY(entry2))
856 return 1;
857 if (entry1->e_hash != entry2->e_hash ||
858 entry1->e_name_index != entry2->e_name_index ||
859 entry1->e_name_len != entry2->e_name_len ||
860 entry1->e_value_size != entry2->e_value_size ||
861 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
862 return 1;
863 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
864 return -EIO;
865 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
866 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
867 le32_to_cpu(entry1->e_value_size)))
868 return 1;
869
870 entry1 = EXT2_XATTR_NEXT(entry1);
871 entry2 = EXT2_XATTR_NEXT(entry2);
872 }
873 if (!IS_LAST_ENTRY(entry2))
874 return 1;
875 return 0;
876}
877
878/*
879 * ext2_xattr_cache_find()
880 *
881 * Find an identical extended attribute block.
882 *
883 * Returns a locked buffer head to the block found, or NULL if such
884 * a block was not found or an error occurred.
885 */
886static struct buffer_head *
887ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
888{
889 __u32 hash = le32_to_cpu(header->h_hash);
890 struct mb_cache_entry *ce;
891 struct mb_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache;
892
893 if (!header->h_hash)
894 return NULL; /* never share */
895 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
896again:
897 ce = mb_cache_entry_find_first(ext2_mb_cache, hash);
898 while (ce) {
899 struct buffer_head *bh;
900
901 bh = sb_bread(inode->i_sb, ce->e_block);
902 if (!bh) {
903 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
904 "inode %ld: block %ld read error",
905 inode->i_ino, (unsigned long) ce->e_block);
906 } else {
907 lock_buffer(bh);
908 /*
909 * We have to be careful about races with freeing or
910 * rehashing of xattr block. Once we hold buffer lock
911 * xattr block's state is stable so we can check
912 * whether the block got freed / rehashed or not.
913 * Since we unhash mbcache entry under buffer lock when
914 * freeing / rehashing xattr block, checking whether
915 * entry is still hashed is reliable.
916 */
917 if (hlist_bl_unhashed(&ce->e_hash_list)) {
918 mb_cache_entry_put(ext2_mb_cache, ce);
919 unlock_buffer(bh);
920 brelse(bh);
921 goto again;
922 } else if (le32_to_cpu(HDR(bh)->h_refcount) >
923 EXT2_XATTR_REFCOUNT_MAX) {
924 ea_idebug(inode, "block %ld refcount %d>%d",
925 (unsigned long) ce->e_block,
926 le32_to_cpu(HDR(bh)->h_refcount),
927 EXT2_XATTR_REFCOUNT_MAX);
928 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
929 ea_bdebug(bh, "b_count=%d",
930 atomic_read(&(bh->b_count)));
931 mb_cache_entry_touch(ext2_mb_cache, ce);
932 mb_cache_entry_put(ext2_mb_cache, ce);
933 return bh;
934 }
935 unlock_buffer(bh);
936 brelse(bh);
937 }
938 ce = mb_cache_entry_find_next(ext2_mb_cache, ce);
939 }
940 return NULL;
941}
942
943#define NAME_HASH_SHIFT 5
944#define VALUE_HASH_SHIFT 16
945
946/*
947 * ext2_xattr_hash_entry()
948 *
949 * Compute the hash of an extended attribute.
950 */
951static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
952 struct ext2_xattr_entry *entry)
953{
954 __u32 hash = 0;
955 char *name = entry->e_name;
956 int n;
957
958 for (n=0; n < entry->e_name_len; n++) {
959 hash = (hash << NAME_HASH_SHIFT) ^
960 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
961 *name++;
962 }
963
964 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
965 __le32 *value = (__le32 *)((char *)header +
966 le16_to_cpu(entry->e_value_offs));
967 for (n = (le32_to_cpu(entry->e_value_size) +
968 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
969 hash = (hash << VALUE_HASH_SHIFT) ^
970 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
971 le32_to_cpu(*value++);
972 }
973 }
974 entry->e_hash = cpu_to_le32(hash);
975}
976
977#undef NAME_HASH_SHIFT
978#undef VALUE_HASH_SHIFT
979
980#define BLOCK_HASH_SHIFT 16
981
982/*
983 * ext2_xattr_rehash()
984 *
985 * Re-compute the extended attribute hash value after an entry has changed.
986 */
987static void ext2_xattr_rehash(struct ext2_xattr_header *header,
988 struct ext2_xattr_entry *entry)
989{
990 struct ext2_xattr_entry *here;
991 __u32 hash = 0;
992
993 ext2_xattr_hash_entry(header, entry);
994 here = ENTRY(header+1);
995 while (!IS_LAST_ENTRY(here)) {
996 if (!here->e_hash) {
997 /* Block is not shared if an entry's hash value == 0 */
998 hash = 0;
999 break;
1000 }
1001 hash = (hash << BLOCK_HASH_SHIFT) ^
1002 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1003 le32_to_cpu(here->e_hash);
1004 here = EXT2_XATTR_NEXT(here);
1005 }
1006 header->h_hash = cpu_to_le32(hash);
1007}
1008
1009#undef BLOCK_HASH_SHIFT
1010
1011#define HASH_BUCKET_BITS 10
1012
1013struct mb_cache *ext2_xattr_create_cache(void)
1014{
1015 return mb_cache_create(HASH_BUCKET_BITS);
1016}
1017
1018void ext2_xattr_destroy_cache(struct mb_cache *cache)
1019{
1020 if (cache)
1021 mb_cache_destroy(cache);
1022}