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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(inode);
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 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
763
764 down_write(&EXT2_I(inode)->xattr_sem);
765 if (!EXT2_I(inode)->i_file_acl)
766 goto cleanup;
767
768 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 0)) {
769 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
770 "inode %ld: xattr block %d is out of data blocks range",
771 inode->i_ino, EXT2_I(inode)->i_file_acl);
772 goto cleanup;
773 }
774
775 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
776 if (!bh) {
777 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
778 "inode %ld: block %d read error", inode->i_ino,
779 EXT2_I(inode)->i_file_acl);
780 goto cleanup;
781 }
782 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
783 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
784 HDR(bh)->h_blocks != cpu_to_le32(1)) {
785 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
786 "inode %ld: bad block %d", inode->i_ino,
787 EXT2_I(inode)->i_file_acl);
788 goto cleanup;
789 }
790 lock_buffer(bh);
791 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
792 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
793
794 /*
795 * This must happen under buffer lock for ext2_xattr_set2() to
796 * reliably detect freed block
797 */
798 mb_cache_entry_delete_block(EXT2_SB(inode->i_sb)->s_mb_cache,
799 hash, bh->b_blocknr);
800 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
801 get_bh(bh);
802 bforget(bh);
803 unlock_buffer(bh);
804 } else {
805 le32_add_cpu(&HDR(bh)->h_refcount, -1);
806 ea_bdebug(bh, "refcount now=%d",
807 le32_to_cpu(HDR(bh)->h_refcount));
808 unlock_buffer(bh);
809 mark_buffer_dirty(bh);
810 if (IS_SYNC(inode))
811 sync_dirty_buffer(bh);
812 dquot_free_block_nodirty(inode, 1);
813 }
814 EXT2_I(inode)->i_file_acl = 0;
815
816cleanup:
817 brelse(bh);
818 up_write(&EXT2_I(inode)->xattr_sem);
819}
820
821/*
822 * ext2_xattr_cache_insert()
823 *
824 * Create a new entry in the extended attribute cache, and insert
825 * it unless such an entry is already in the cache.
826 *
827 * Returns 0, or a negative error number on failure.
828 */
829static int
830ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)
831{
832 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
833 int error;
834
835 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, 1);
836 if (error) {
837 if (error == -EBUSY) {
838 ea_bdebug(bh, "already in cache (%d cache entries)",
839 atomic_read(&ext2_xattr_cache->c_entry_count));
840 error = 0;
841 }
842 } else
843 ea_bdebug(bh, "inserting [%x]", (int)hash);
844 return error;
845}
846
847/*
848 * ext2_xattr_cmp()
849 *
850 * Compare two extended attribute blocks for equality.
851 *
852 * Returns 0 if the blocks are equal, 1 if they differ, and
853 * a negative error number on errors.
854 */
855static int
856ext2_xattr_cmp(struct ext2_xattr_header *header1,
857 struct ext2_xattr_header *header2)
858{
859 struct ext2_xattr_entry *entry1, *entry2;
860
861 entry1 = ENTRY(header1+1);
862 entry2 = ENTRY(header2+1);
863 while (!IS_LAST_ENTRY(entry1)) {
864 if (IS_LAST_ENTRY(entry2))
865 return 1;
866 if (entry1->e_hash != entry2->e_hash ||
867 entry1->e_name_index != entry2->e_name_index ||
868 entry1->e_name_len != entry2->e_name_len ||
869 entry1->e_value_size != entry2->e_value_size ||
870 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
871 return 1;
872 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
873 return -EIO;
874 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
875 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
876 le32_to_cpu(entry1->e_value_size)))
877 return 1;
878
879 entry1 = EXT2_XATTR_NEXT(entry1);
880 entry2 = EXT2_XATTR_NEXT(entry2);
881 }
882 if (!IS_LAST_ENTRY(entry2))
883 return 1;
884 return 0;
885}
886
887/*
888 * ext2_xattr_cache_find()
889 *
890 * Find an identical extended attribute block.
891 *
892 * Returns a locked buffer head to the block found, or NULL if such
893 * a block was not found or an error occurred.
894 */
895static struct buffer_head *
896ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
897{
898 __u32 hash = le32_to_cpu(header->h_hash);
899 struct mb_cache_entry *ce;
900 struct mb_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache;
901
902 if (!header->h_hash)
903 return NULL; /* never share */
904 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
905again:
906 ce = mb_cache_entry_find_first(ext2_mb_cache, hash);
907 while (ce) {
908 struct buffer_head *bh;
909
910 bh = sb_bread(inode->i_sb, ce->e_block);
911 if (!bh) {
912 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
913 "inode %ld: block %ld read error",
914 inode->i_ino, (unsigned long) ce->e_block);
915 } else {
916 lock_buffer(bh);
917 /*
918 * We have to be careful about races with freeing or
919 * rehashing of xattr block. Once we hold buffer lock
920 * xattr block's state is stable so we can check
921 * whether the block got freed / rehashed or not.
922 * Since we unhash mbcache entry under buffer lock when
923 * freeing / rehashing xattr block, checking whether
924 * entry is still hashed is reliable.
925 */
926 if (hlist_bl_unhashed(&ce->e_hash_list)) {
927 mb_cache_entry_put(ext2_mb_cache, ce);
928 unlock_buffer(bh);
929 brelse(bh);
930 goto again;
931 } else if (le32_to_cpu(HDR(bh)->h_refcount) >
932 EXT2_XATTR_REFCOUNT_MAX) {
933 ea_idebug(inode, "block %ld refcount %d>%d",
934 (unsigned long) ce->e_block,
935 le32_to_cpu(HDR(bh)->h_refcount),
936 EXT2_XATTR_REFCOUNT_MAX);
937 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
938 ea_bdebug(bh, "b_count=%d",
939 atomic_read(&(bh->b_count)));
940 mb_cache_entry_touch(ext2_mb_cache, ce);
941 mb_cache_entry_put(ext2_mb_cache, ce);
942 return bh;
943 }
944 unlock_buffer(bh);
945 brelse(bh);
946 }
947 ce = mb_cache_entry_find_next(ext2_mb_cache, ce);
948 }
949 return NULL;
950}
951
952#define NAME_HASH_SHIFT 5
953#define VALUE_HASH_SHIFT 16
954
955/*
956 * ext2_xattr_hash_entry()
957 *
958 * Compute the hash of an extended attribute.
959 */
960static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
961 struct ext2_xattr_entry *entry)
962{
963 __u32 hash = 0;
964 char *name = entry->e_name;
965 int n;
966
967 for (n=0; n < entry->e_name_len; n++) {
968 hash = (hash << NAME_HASH_SHIFT) ^
969 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
970 *name++;
971 }
972
973 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
974 __le32 *value = (__le32 *)((char *)header +
975 le16_to_cpu(entry->e_value_offs));
976 for (n = (le32_to_cpu(entry->e_value_size) +
977 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
978 hash = (hash << VALUE_HASH_SHIFT) ^
979 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
980 le32_to_cpu(*value++);
981 }
982 }
983 entry->e_hash = cpu_to_le32(hash);
984}
985
986#undef NAME_HASH_SHIFT
987#undef VALUE_HASH_SHIFT
988
989#define BLOCK_HASH_SHIFT 16
990
991/*
992 * ext2_xattr_rehash()
993 *
994 * Re-compute the extended attribute hash value after an entry has changed.
995 */
996static void ext2_xattr_rehash(struct ext2_xattr_header *header,
997 struct ext2_xattr_entry *entry)
998{
999 struct ext2_xattr_entry *here;
1000 __u32 hash = 0;
1001
1002 ext2_xattr_hash_entry(header, entry);
1003 here = ENTRY(header+1);
1004 while (!IS_LAST_ENTRY(here)) {
1005 if (!here->e_hash) {
1006 /* Block is not shared if an entry's hash value == 0 */
1007 hash = 0;
1008 break;
1009 }
1010 hash = (hash << BLOCK_HASH_SHIFT) ^
1011 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1012 le32_to_cpu(here->e_hash);
1013 here = EXT2_XATTR_NEXT(here);
1014 }
1015 header->h_hash = cpu_to_le32(hash);
1016}
1017
1018#undef BLOCK_HASH_SHIFT
1019
1020#define HASH_BUCKET_BITS 10
1021
1022struct mb_cache *ext2_xattr_create_cache(void)
1023{
1024 return mb_cache_create(HASH_BUCKET_BITS);
1025}
1026
1027void ext2_xattr_destroy_cache(struct mb_cache *cache)
1028{
1029 if (cache)
1030 mb_cache_destroy(cache);
1031}
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 char b[BDEVNAME_SIZE]; \
81 printk(KERN_DEBUG "block %s:%lu: ", \
82 bdevname(bh->b_bdev, b), \
83 (unsigned long) bh->b_blocknr); \
84 printk(f); \
85 printk("\n"); \
86 } while (0)
87#else
88# define ea_idebug(f...)
89# define ea_bdebug(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 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 struct mb_cache *ext2_xattr_cache;
102
103static const struct xattr_handler *ext2_xattr_handler_map[] = {
104 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
105#ifdef CONFIG_EXT2_FS_POSIX_ACL
106 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler,
107 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler,
108#endif
109 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
110#ifdef CONFIG_EXT2_FS_SECURITY
111 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
112#endif
113};
114
115const struct xattr_handler *ext2_xattr_handlers[] = {
116 &ext2_xattr_user_handler,
117 &ext2_xattr_trusted_handler,
118#ifdef CONFIG_EXT2_FS_POSIX_ACL
119 &ext2_xattr_acl_access_handler,
120 &ext2_xattr_acl_default_handler,
121#endif
122#ifdef CONFIG_EXT2_FS_SECURITY
123 &ext2_xattr_security_handler,
124#endif
125 NULL
126};
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
138/*
139 * ext2_xattr_get()
140 *
141 * Copy an extended attribute into the buffer
142 * provided, or compute the buffer size required.
143 * Buffer is NULL to compute the size of the buffer required.
144 *
145 * Returns a negative error number on failure, or the number of bytes
146 * used / required on success.
147 */
148int
149ext2_xattr_get(struct inode *inode, int name_index, const char *name,
150 void *buffer, size_t buffer_size)
151{
152 struct buffer_head *bh = NULL;
153 struct ext2_xattr_entry *entry;
154 size_t name_len, size;
155 char *end;
156 int error;
157
158 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
159 name_index, name, buffer, (long)buffer_size);
160
161 if (name == NULL)
162 return -EINVAL;
163 name_len = strlen(name);
164 if (name_len > 255)
165 return -ERANGE;
166
167 down_read(&EXT2_I(inode)->xattr_sem);
168 error = -ENODATA;
169 if (!EXT2_I(inode)->i_file_acl)
170 goto cleanup;
171 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
172 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
173 error = -EIO;
174 if (!bh)
175 goto cleanup;
176 ea_bdebug(bh, "b_count=%d, refcount=%d",
177 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
178 end = bh->b_data + bh->b_size;
179 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
180 HDR(bh)->h_blocks != cpu_to_le32(1)) {
181bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
182 "inode %ld: bad block %d", inode->i_ino,
183 EXT2_I(inode)->i_file_acl);
184 error = -EIO;
185 goto cleanup;
186 }
187
188 /* find named attribute */
189 entry = FIRST_ENTRY(bh);
190 while (!IS_LAST_ENTRY(entry)) {
191 struct ext2_xattr_entry *next =
192 EXT2_XATTR_NEXT(entry);
193 if ((char *)next >= end)
194 goto bad_block;
195 if (name_index == entry->e_name_index &&
196 name_len == entry->e_name_len &&
197 memcmp(name, entry->e_name, name_len) == 0)
198 goto found;
199 entry = next;
200 }
201 if (ext2_xattr_cache_insert(bh))
202 ea_idebug(inode, "cache insert failed");
203 error = -ENODATA;
204 goto cleanup;
205found:
206 /* check the buffer size */
207 if (entry->e_value_block != 0)
208 goto bad_block;
209 size = le32_to_cpu(entry->e_value_size);
210 if (size > inode->i_sb->s_blocksize ||
211 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
212 goto bad_block;
213
214 if (ext2_xattr_cache_insert(bh))
215 ea_idebug(inode, "cache insert failed");
216 if (buffer) {
217 error = -ERANGE;
218 if (size > buffer_size)
219 goto cleanup;
220 /* return value of attribute */
221 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
222 size);
223 }
224 error = size;
225
226cleanup:
227 brelse(bh);
228 up_read(&EXT2_I(inode)->xattr_sem);
229
230 return error;
231}
232
233/*
234 * ext2_xattr_list()
235 *
236 * Copy a list of attribute names into the buffer
237 * provided, or compute the buffer size required.
238 * Buffer is NULL to compute the size of the buffer required.
239 *
240 * Returns a negative error number on failure, or the number of bytes
241 * used / required on success.
242 */
243static int
244ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
245{
246 struct inode *inode = dentry->d_inode;
247 struct buffer_head *bh = NULL;
248 struct ext2_xattr_entry *entry;
249 char *end;
250 size_t rest = buffer_size;
251 int error;
252
253 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
254 buffer, (long)buffer_size);
255
256 down_read(&EXT2_I(inode)->xattr_sem);
257 error = 0;
258 if (!EXT2_I(inode)->i_file_acl)
259 goto cleanup;
260 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
261 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
262 error = -EIO;
263 if (!bh)
264 goto cleanup;
265 ea_bdebug(bh, "b_count=%d, refcount=%d",
266 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
267 end = bh->b_data + bh->b_size;
268 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
269 HDR(bh)->h_blocks != cpu_to_le32(1)) {
270bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
271 "inode %ld: bad block %d", inode->i_ino,
272 EXT2_I(inode)->i_file_acl);
273 error = -EIO;
274 goto cleanup;
275 }
276
277 /* check the on-disk data structure */
278 entry = FIRST_ENTRY(bh);
279 while (!IS_LAST_ENTRY(entry)) {
280 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
281
282 if ((char *)next >= end)
283 goto bad_block;
284 entry = next;
285 }
286 if (ext2_xattr_cache_insert(bh))
287 ea_idebug(inode, "cache insert failed");
288
289 /* list the attribute names */
290 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
291 entry = EXT2_XATTR_NEXT(entry)) {
292 const struct xattr_handler *handler =
293 ext2_xattr_handler(entry->e_name_index);
294
295 if (handler) {
296 size_t size = handler->list(dentry, buffer, rest,
297 entry->e_name,
298 entry->e_name_len,
299 handler->flags);
300 if (buffer) {
301 if (size > rest) {
302 error = -ERANGE;
303 goto cleanup;
304 }
305 buffer += size;
306 }
307 rest -= size;
308 }
309 }
310 error = buffer_size - rest; /* total size */
311
312cleanup:
313 brelse(bh);
314 up_read(&EXT2_I(inode)->xattr_sem);
315
316 return error;
317}
318
319/*
320 * Inode operation listxattr()
321 *
322 * dentry->d_inode->i_mutex: don't care
323 */
324ssize_t
325ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
326{
327 return ext2_xattr_list(dentry, buffer, size);
328}
329
330/*
331 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
332 * not set, set it.
333 */
334static void ext2_xattr_update_super_block(struct super_block *sb)
335{
336 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
337 return;
338
339 spin_lock(&EXT2_SB(sb)->s_lock);
340 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
341 spin_unlock(&EXT2_SB(sb)->s_lock);
342 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
343}
344
345/*
346 * ext2_xattr_set()
347 *
348 * Create, replace or remove an extended attribute for this inode. Value
349 * is NULL to remove an existing extended attribute, and non-NULL to
350 * either replace an existing extended attribute, or create a new extended
351 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
352 * specify that an extended attribute must exist and must not exist
353 * previous to the call, respectively.
354 *
355 * Returns 0, or a negative error number on failure.
356 */
357int
358ext2_xattr_set(struct inode *inode, int name_index, const char *name,
359 const void *value, size_t value_len, int flags)
360{
361 struct super_block *sb = inode->i_sb;
362 struct buffer_head *bh = NULL;
363 struct ext2_xattr_header *header = NULL;
364 struct ext2_xattr_entry *here, *last;
365 size_t name_len, free, min_offs = sb->s_blocksize;
366 int not_found = 1, error;
367 char *end;
368
369 /*
370 * header -- Points either into bh, or to a temporarily
371 * allocated buffer.
372 * here -- The named entry found, or the place for inserting, within
373 * the block pointed to by header.
374 * last -- Points right after the last named entry within the block
375 * pointed to by header.
376 * min_offs -- The offset of the first value (values are aligned
377 * towards the end of the block).
378 * end -- Points right after the block pointed to by header.
379 */
380
381 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
382 name_index, name, value, (long)value_len);
383
384 if (value == NULL)
385 value_len = 0;
386 if (name == NULL)
387 return -EINVAL;
388 name_len = strlen(name);
389 if (name_len > 255 || value_len > sb->s_blocksize)
390 return -ERANGE;
391 down_write(&EXT2_I(inode)->xattr_sem);
392 if (EXT2_I(inode)->i_file_acl) {
393 /* The inode already has an extended attribute block. */
394 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
395 error = -EIO;
396 if (!bh)
397 goto cleanup;
398 ea_bdebug(bh, "b_count=%d, refcount=%d",
399 atomic_read(&(bh->b_count)),
400 le32_to_cpu(HDR(bh)->h_refcount));
401 header = HDR(bh);
402 end = bh->b_data + bh->b_size;
403 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
404 header->h_blocks != cpu_to_le32(1)) {
405bad_block: ext2_error(sb, "ext2_xattr_set",
406 "inode %ld: bad block %d", inode->i_ino,
407 EXT2_I(inode)->i_file_acl);
408 error = -EIO;
409 goto cleanup;
410 }
411 /* Find the named attribute. */
412 here = FIRST_ENTRY(bh);
413 while (!IS_LAST_ENTRY(here)) {
414 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
415 if ((char *)next >= end)
416 goto bad_block;
417 if (!here->e_value_block && here->e_value_size) {
418 size_t offs = le16_to_cpu(here->e_value_offs);
419 if (offs < min_offs)
420 min_offs = offs;
421 }
422 not_found = name_index - here->e_name_index;
423 if (!not_found)
424 not_found = name_len - here->e_name_len;
425 if (!not_found)
426 not_found = memcmp(name, here->e_name,name_len);
427 if (not_found <= 0)
428 break;
429 here = next;
430 }
431 last = here;
432 /* We still need to compute min_offs and last. */
433 while (!IS_LAST_ENTRY(last)) {
434 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
435 if ((char *)next >= end)
436 goto bad_block;
437 if (!last->e_value_block && last->e_value_size) {
438 size_t offs = le16_to_cpu(last->e_value_offs);
439 if (offs < min_offs)
440 min_offs = offs;
441 }
442 last = next;
443 }
444
445 /* Check whether we have enough space left. */
446 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
447 } else {
448 /* We will use a new extended attribute block. */
449 free = sb->s_blocksize -
450 sizeof(struct ext2_xattr_header) - sizeof(__u32);
451 here = last = NULL; /* avoid gcc uninitialized warning. */
452 }
453
454 if (not_found) {
455 /* Request to remove a nonexistent attribute? */
456 error = -ENODATA;
457 if (flags & XATTR_REPLACE)
458 goto cleanup;
459 error = 0;
460 if (value == NULL)
461 goto cleanup;
462 } else {
463 /* Request to create an existing attribute? */
464 error = -EEXIST;
465 if (flags & XATTR_CREATE)
466 goto cleanup;
467 if (!here->e_value_block && here->e_value_size) {
468 size_t size = le32_to_cpu(here->e_value_size);
469
470 if (le16_to_cpu(here->e_value_offs) + size >
471 sb->s_blocksize || size > sb->s_blocksize)
472 goto bad_block;
473 free += EXT2_XATTR_SIZE(size);
474 }
475 free += EXT2_XATTR_LEN(name_len);
476 }
477 error = -ENOSPC;
478 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
479 goto cleanup;
480
481 /* Here we know that we can set the new attribute. */
482
483 if (header) {
484 struct mb_cache_entry *ce;
485
486 /* assert(header == HDR(bh)); */
487 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
488 bh->b_blocknr);
489 lock_buffer(bh);
490 if (header->h_refcount == cpu_to_le32(1)) {
491 ea_bdebug(bh, "modifying in-place");
492 if (ce)
493 mb_cache_entry_free(ce);
494 /* keep the buffer locked while modifying it. */
495 } else {
496 int offset;
497
498 if (ce)
499 mb_cache_entry_release(ce);
500 unlock_buffer(bh);
501 ea_bdebug(bh, "cloning");
502 header = kmalloc(bh->b_size, GFP_KERNEL);
503 error = -ENOMEM;
504 if (header == NULL)
505 goto cleanup;
506 memcpy(header, HDR(bh), bh->b_size);
507 header->h_refcount = cpu_to_le32(1);
508
509 offset = (char *)here - bh->b_data;
510 here = ENTRY((char *)header + offset);
511 offset = (char *)last - bh->b_data;
512 last = ENTRY((char *)header + offset);
513 }
514 } else {
515 /* Allocate a buffer where we construct the new block. */
516 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
517 error = -ENOMEM;
518 if (header == NULL)
519 goto cleanup;
520 end = (char *)header + sb->s_blocksize;
521 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
522 header->h_blocks = header->h_refcount = cpu_to_le32(1);
523 last = here = ENTRY(header+1);
524 }
525
526 /* Iff we are modifying the block in-place, bh is locked here. */
527
528 if (not_found) {
529 /* Insert the new name. */
530 size_t size = EXT2_XATTR_LEN(name_len);
531 size_t rest = (char *)last - (char *)here;
532 memmove((char *)here + size, here, rest);
533 memset(here, 0, size);
534 here->e_name_index = name_index;
535 here->e_name_len = name_len;
536 memcpy(here->e_name, name, name_len);
537 } else {
538 if (!here->e_value_block && here->e_value_size) {
539 char *first_val = (char *)header + min_offs;
540 size_t offs = le16_to_cpu(here->e_value_offs);
541 char *val = (char *)header + offs;
542 size_t size = EXT2_XATTR_SIZE(
543 le32_to_cpu(here->e_value_size));
544
545 if (size == EXT2_XATTR_SIZE(value_len)) {
546 /* The old and the new value have the same
547 size. Just replace. */
548 here->e_value_size = cpu_to_le32(value_len);
549 memset(val + size - EXT2_XATTR_PAD, 0,
550 EXT2_XATTR_PAD); /* Clear pad bytes. */
551 memcpy(val, value, value_len);
552 goto skip_replace;
553 }
554
555 /* Remove the old value. */
556 memmove(first_val + size, first_val, val - first_val);
557 memset(first_val, 0, size);
558 here->e_value_offs = 0;
559 min_offs += size;
560
561 /* Adjust all value offsets. */
562 last = ENTRY(header+1);
563 while (!IS_LAST_ENTRY(last)) {
564 size_t o = le16_to_cpu(last->e_value_offs);
565 if (!last->e_value_block && o < offs)
566 last->e_value_offs =
567 cpu_to_le16(o + size);
568 last = EXT2_XATTR_NEXT(last);
569 }
570 }
571 if (value == NULL) {
572 /* Remove the old name. */
573 size_t size = EXT2_XATTR_LEN(name_len);
574 last = ENTRY((char *)last - size);
575 memmove(here, (char*)here + size,
576 (char*)last - (char*)here);
577 memset(last, 0, size);
578 }
579 }
580
581 if (value != NULL) {
582 /* Insert the new value. */
583 here->e_value_size = cpu_to_le32(value_len);
584 if (value_len) {
585 size_t size = EXT2_XATTR_SIZE(value_len);
586 char *val = (char *)header + min_offs - size;
587 here->e_value_offs =
588 cpu_to_le16((char *)val - (char *)header);
589 memset(val + size - EXT2_XATTR_PAD, 0,
590 EXT2_XATTR_PAD); /* Clear the pad bytes. */
591 memcpy(val, value, value_len);
592 }
593 }
594
595skip_replace:
596 if (IS_LAST_ENTRY(ENTRY(header+1))) {
597 /* This block is now empty. */
598 if (bh && header == HDR(bh))
599 unlock_buffer(bh); /* we were modifying in-place. */
600 error = ext2_xattr_set2(inode, bh, NULL);
601 } else {
602 ext2_xattr_rehash(header, here);
603 if (bh && header == HDR(bh))
604 unlock_buffer(bh); /* we were modifying in-place. */
605 error = ext2_xattr_set2(inode, bh, header);
606 }
607
608cleanup:
609 brelse(bh);
610 if (!(bh && header == HDR(bh)))
611 kfree(header);
612 up_write(&EXT2_I(inode)->xattr_sem);
613
614 return error;
615}
616
617/*
618 * Second half of ext2_xattr_set(): Update the file system.
619 */
620static int
621ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
622 struct ext2_xattr_header *header)
623{
624 struct super_block *sb = inode->i_sb;
625 struct buffer_head *new_bh = NULL;
626 int error;
627
628 if (header) {
629 new_bh = ext2_xattr_cache_find(inode, header);
630 if (new_bh) {
631 /* We found an identical block in the cache. */
632 if (new_bh == old_bh) {
633 ea_bdebug(new_bh, "keeping this block");
634 } else {
635 /* The old block is released after updating
636 the inode. */
637 ea_bdebug(new_bh, "reusing block");
638
639 error = dquot_alloc_block(inode, 1);
640 if (error) {
641 unlock_buffer(new_bh);
642 goto cleanup;
643 }
644 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
645 ea_bdebug(new_bh, "refcount now=%d",
646 le32_to_cpu(HDR(new_bh)->h_refcount));
647 }
648 unlock_buffer(new_bh);
649 } else if (old_bh && header == HDR(old_bh)) {
650 /* Keep this block. No need to lock the block as we
651 don't need to change the reference count. */
652 new_bh = old_bh;
653 get_bh(new_bh);
654 ext2_xattr_cache_insert(new_bh);
655 } else {
656 /* We need to allocate a new block */
657 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
658 EXT2_I(inode)->i_block_group);
659 int block = ext2_new_block(inode, goal, &error);
660 if (error)
661 goto cleanup;
662 ea_idebug(inode, "creating block %d", block);
663
664 new_bh = sb_getblk(sb, block);
665 if (!new_bh) {
666 ext2_free_blocks(inode, block, 1);
667 mark_inode_dirty(inode);
668 error = -EIO;
669 goto cleanup;
670 }
671 lock_buffer(new_bh);
672 memcpy(new_bh->b_data, header, new_bh->b_size);
673 set_buffer_uptodate(new_bh);
674 unlock_buffer(new_bh);
675 ext2_xattr_cache_insert(new_bh);
676
677 ext2_xattr_update_super_block(sb);
678 }
679 mark_buffer_dirty(new_bh);
680 if (IS_SYNC(inode)) {
681 sync_dirty_buffer(new_bh);
682 error = -EIO;
683 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
684 goto cleanup;
685 }
686 }
687
688 /* Update the inode. */
689 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
690 inode->i_ctime = CURRENT_TIME_SEC;
691 if (IS_SYNC(inode)) {
692 error = sync_inode_metadata(inode, 1);
693 /* In case sync failed due to ENOSPC the inode was actually
694 * written (only some dirty data were not) so we just proceed
695 * as if nothing happened and cleanup the unused block */
696 if (error && error != -ENOSPC) {
697 if (new_bh && new_bh != old_bh) {
698 dquot_free_block_nodirty(inode, 1);
699 mark_inode_dirty(inode);
700 }
701 goto cleanup;
702 }
703 } else
704 mark_inode_dirty(inode);
705
706 error = 0;
707 if (old_bh && old_bh != new_bh) {
708 struct mb_cache_entry *ce;
709
710 /*
711 * If there was an old block and we are no longer using it,
712 * release the old block.
713 */
714 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
715 old_bh->b_blocknr);
716 lock_buffer(old_bh);
717 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
718 /* Free the old block. */
719 if (ce)
720 mb_cache_entry_free(ce);
721 ea_bdebug(old_bh, "freeing");
722 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
723 mark_inode_dirty(inode);
724 /* We let our caller release old_bh, so we
725 * need to duplicate the buffer before. */
726 get_bh(old_bh);
727 bforget(old_bh);
728 } else {
729 /* Decrement the refcount only. */
730 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
731 if (ce)
732 mb_cache_entry_release(ce);
733 dquot_free_block_nodirty(inode, 1);
734 mark_inode_dirty(inode);
735 mark_buffer_dirty(old_bh);
736 ea_bdebug(old_bh, "refcount now=%d",
737 le32_to_cpu(HDR(old_bh)->h_refcount));
738 }
739 unlock_buffer(old_bh);
740 }
741
742cleanup:
743 brelse(new_bh);
744
745 return error;
746}
747
748/*
749 * ext2_xattr_delete_inode()
750 *
751 * Free extended attribute resources associated with this inode. This
752 * is called immediately before an inode is freed.
753 */
754void
755ext2_xattr_delete_inode(struct inode *inode)
756{
757 struct buffer_head *bh = NULL;
758 struct mb_cache_entry *ce;
759
760 down_write(&EXT2_I(inode)->xattr_sem);
761 if (!EXT2_I(inode)->i_file_acl)
762 goto cleanup;
763 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
764 if (!bh) {
765 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
766 "inode %ld: block %d read error", inode->i_ino,
767 EXT2_I(inode)->i_file_acl);
768 goto cleanup;
769 }
770 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
771 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
772 HDR(bh)->h_blocks != cpu_to_le32(1)) {
773 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
774 "inode %ld: bad block %d", inode->i_ino,
775 EXT2_I(inode)->i_file_acl);
776 goto cleanup;
777 }
778 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
779 lock_buffer(bh);
780 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
781 if (ce)
782 mb_cache_entry_free(ce);
783 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
784 get_bh(bh);
785 bforget(bh);
786 unlock_buffer(bh);
787 } else {
788 le32_add_cpu(&HDR(bh)->h_refcount, -1);
789 if (ce)
790 mb_cache_entry_release(ce);
791 ea_bdebug(bh, "refcount now=%d",
792 le32_to_cpu(HDR(bh)->h_refcount));
793 unlock_buffer(bh);
794 mark_buffer_dirty(bh);
795 if (IS_SYNC(inode))
796 sync_dirty_buffer(bh);
797 dquot_free_block_nodirty(inode, 1);
798 }
799 EXT2_I(inode)->i_file_acl = 0;
800
801cleanup:
802 brelse(bh);
803 up_write(&EXT2_I(inode)->xattr_sem);
804}
805
806/*
807 * ext2_xattr_put_super()
808 *
809 * This is called when a file system is unmounted.
810 */
811void
812ext2_xattr_put_super(struct super_block *sb)
813{
814 mb_cache_shrink(sb->s_bdev);
815}
816
817
818/*
819 * ext2_xattr_cache_insert()
820 *
821 * Create a new entry in the extended attribute cache, and insert
822 * it unless such an entry is already in the cache.
823 *
824 * Returns 0, or a negative error number on failure.
825 */
826static int
827ext2_xattr_cache_insert(struct buffer_head *bh)
828{
829 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
830 struct mb_cache_entry *ce;
831 int error;
832
833 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
834 if (!ce)
835 return -ENOMEM;
836 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
837 if (error) {
838 mb_cache_entry_free(ce);
839 if (error == -EBUSY) {
840 ea_bdebug(bh, "already in cache (%d cache entries)",
841 atomic_read(&ext2_xattr_cache->c_entry_count));
842 error = 0;
843 }
844 } else {
845 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
846 atomic_read(&ext2_xattr_cache->c_entry_count));
847 mb_cache_entry_release(ce);
848 }
849 return error;
850}
851
852/*
853 * ext2_xattr_cmp()
854 *
855 * Compare two extended attribute blocks for equality.
856 *
857 * Returns 0 if the blocks are equal, 1 if they differ, and
858 * a negative error number on errors.
859 */
860static int
861ext2_xattr_cmp(struct ext2_xattr_header *header1,
862 struct ext2_xattr_header *header2)
863{
864 struct ext2_xattr_entry *entry1, *entry2;
865
866 entry1 = ENTRY(header1+1);
867 entry2 = ENTRY(header2+1);
868 while (!IS_LAST_ENTRY(entry1)) {
869 if (IS_LAST_ENTRY(entry2))
870 return 1;
871 if (entry1->e_hash != entry2->e_hash ||
872 entry1->e_name_index != entry2->e_name_index ||
873 entry1->e_name_len != entry2->e_name_len ||
874 entry1->e_value_size != entry2->e_value_size ||
875 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
876 return 1;
877 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
878 return -EIO;
879 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
880 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
881 le32_to_cpu(entry1->e_value_size)))
882 return 1;
883
884 entry1 = EXT2_XATTR_NEXT(entry1);
885 entry2 = EXT2_XATTR_NEXT(entry2);
886 }
887 if (!IS_LAST_ENTRY(entry2))
888 return 1;
889 return 0;
890}
891
892/*
893 * ext2_xattr_cache_find()
894 *
895 * Find an identical extended attribute block.
896 *
897 * Returns a locked buffer head to the block found, or NULL if such
898 * a block was not found or an error occurred.
899 */
900static struct buffer_head *
901ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
902{
903 __u32 hash = le32_to_cpu(header->h_hash);
904 struct mb_cache_entry *ce;
905
906 if (!header->h_hash)
907 return NULL; /* never share */
908 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
909again:
910 ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev,
911 hash);
912 while (ce) {
913 struct buffer_head *bh;
914
915 if (IS_ERR(ce)) {
916 if (PTR_ERR(ce) == -EAGAIN)
917 goto again;
918 break;
919 }
920
921 bh = sb_bread(inode->i_sb, ce->e_block);
922 if (!bh) {
923 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
924 "inode %ld: block %ld read error",
925 inode->i_ino, (unsigned long) ce->e_block);
926 } else {
927 lock_buffer(bh);
928 if (le32_to_cpu(HDR(bh)->h_refcount) >
929 EXT2_XATTR_REFCOUNT_MAX) {
930 ea_idebug(inode, "block %ld refcount %d>%d",
931 (unsigned long) ce->e_block,
932 le32_to_cpu(HDR(bh)->h_refcount),
933 EXT2_XATTR_REFCOUNT_MAX);
934 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
935 ea_bdebug(bh, "b_count=%d",
936 atomic_read(&(bh->b_count)));
937 mb_cache_entry_release(ce);
938 return bh;
939 }
940 unlock_buffer(bh);
941 brelse(bh);
942 }
943 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
944 }
945 return NULL;
946}
947
948#define NAME_HASH_SHIFT 5
949#define VALUE_HASH_SHIFT 16
950
951/*
952 * ext2_xattr_hash_entry()
953 *
954 * Compute the hash of an extended attribute.
955 */
956static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
957 struct ext2_xattr_entry *entry)
958{
959 __u32 hash = 0;
960 char *name = entry->e_name;
961 int n;
962
963 for (n=0; n < entry->e_name_len; n++) {
964 hash = (hash << NAME_HASH_SHIFT) ^
965 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
966 *name++;
967 }
968
969 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
970 __le32 *value = (__le32 *)((char *)header +
971 le16_to_cpu(entry->e_value_offs));
972 for (n = (le32_to_cpu(entry->e_value_size) +
973 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
974 hash = (hash << VALUE_HASH_SHIFT) ^
975 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
976 le32_to_cpu(*value++);
977 }
978 }
979 entry->e_hash = cpu_to_le32(hash);
980}
981
982#undef NAME_HASH_SHIFT
983#undef VALUE_HASH_SHIFT
984
985#define BLOCK_HASH_SHIFT 16
986
987/*
988 * ext2_xattr_rehash()
989 *
990 * Re-compute the extended attribute hash value after an entry has changed.
991 */
992static void ext2_xattr_rehash(struct ext2_xattr_header *header,
993 struct ext2_xattr_entry *entry)
994{
995 struct ext2_xattr_entry *here;
996 __u32 hash = 0;
997
998 ext2_xattr_hash_entry(header, entry);
999 here = ENTRY(header+1);
1000 while (!IS_LAST_ENTRY(here)) {
1001 if (!here->e_hash) {
1002 /* Block is not shared if an entry's hash value == 0 */
1003 hash = 0;
1004 break;
1005 }
1006 hash = (hash << BLOCK_HASH_SHIFT) ^
1007 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1008 le32_to_cpu(here->e_hash);
1009 here = EXT2_XATTR_NEXT(here);
1010 }
1011 header->h_hash = cpu_to_le32(hash);
1012}
1013
1014#undef BLOCK_HASH_SHIFT
1015
1016int __init
1017init_ext2_xattr(void)
1018{
1019 ext2_xattr_cache = mb_cache_create("ext2_xattr", 6);
1020 if (!ext2_xattr_cache)
1021 return -ENOMEM;
1022 return 0;
1023}
1024
1025void
1026exit_ext2_xattr(void)
1027{
1028 mb_cache_destroy(ext2_xattr_cache);
1029}