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