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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext2/xattr.c
4 *
5 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>
6 *
7 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
8 * Extended attributes for symlinks and special files added per
9 * suggestion of Luka Renko <luka.renko@hermes.si>.
10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
11 * Red Hat Inc.
12 *
13 */
14
15/*
16 * Extended attributes are stored on disk blocks allocated outside of
17 * any inode. The i_file_acl field is then made to point to this allocated
18 * block. If all extended attributes of an inode are identical, these
19 * inodes may share the same extended attribute block. Such situations
20 * are automatically detected by keeping a cache of recent attribute block
21 * numbers and hashes over the block's contents in memory.
22 *
23 *
24 * Extended attribute block layout:
25 *
26 * +------------------+
27 * | header |
28 * | entry 1 | |
29 * | entry 2 | | growing downwards
30 * | entry 3 | v
31 * | four null bytes |
32 * | . . . |
33 * | value 1 | ^
34 * | value 3 | | growing upwards
35 * | value 2 | |
36 * +------------------+
37 *
38 * The block header is followed by multiple entry descriptors. These entry
39 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD
40 * byte boundaries. The entry descriptors are sorted by attribute name,
41 * so that two extended attribute blocks can be compared efficiently.
42 *
43 * Attribute values are aligned to the end of the block, stored in
44 * no specific order. They are also padded to EXT2_XATTR_PAD byte
45 * boundaries. No additional gaps are left between them.
46 *
47 * Locking strategy
48 * ----------------
49 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem.
50 * EA blocks are only changed if they are exclusive to an inode, so
51 * holding xattr_sem also means that nothing but the EA block's reference
52 * count will change. Multiple writers to an EA block are synchronized
53 * by the bh lock. No more than a single bh lock is held at any time
54 * to avoid deadlocks.
55 */
56
57#include <linux/buffer_head.h>
58#include <linux/init.h>
59#include <linux/slab.h>
60#include <linux/mbcache.h>
61#include <linux/quotaops.h>
62#include <linux/rwsem.h>
63#include <linux/security.h>
64#include "ext2.h"
65#include "xattr.h"
66#include "acl.h"
67
68#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
69#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
70#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
71#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
72
73#ifdef EXT2_XATTR_DEBUG
74# define ea_idebug(inode, f...) do { \
75 printk(KERN_DEBUG "inode %s:%ld: ", \
76 inode->i_sb->s_id, inode->i_ino); \
77 printk(f); \
78 printk("\n"); \
79 } while (0)
80# define ea_bdebug(bh, f...) do { \
81 printk(KERN_DEBUG "block %pg:%lu: ", \
82 bh->b_bdev, (unsigned long) bh->b_blocknr); \
83 printk(f); \
84 printk("\n"); \
85 } while (0)
86#else
87# define ea_idebug(f...)
88# define ea_bdebug(f...)
89#endif
90
91static int ext2_xattr_set2(struct inode *, struct buffer_head *,
92 struct ext2_xattr_header *);
93
94static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
95static struct buffer_head *ext2_xattr_cache_find(struct inode *,
96 struct ext2_xattr_header *);
97static void ext2_xattr_rehash(struct ext2_xattr_header *,
98 struct ext2_xattr_entry *);
99
100static const struct xattr_handler *ext2_xattr_handler_map[] = {
101 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
102#ifdef CONFIG_EXT2_FS_POSIX_ACL
103 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler,
104 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
105#endif
106 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
107#ifdef CONFIG_EXT2_FS_SECURITY
108 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
109#endif
110};
111
112const struct xattr_handler *ext2_xattr_handlers[] = {
113 &ext2_xattr_user_handler,
114 &ext2_xattr_trusted_handler,
115#ifdef CONFIG_EXT2_FS_POSIX_ACL
116 &posix_acl_access_xattr_handler,
117 &posix_acl_default_xattr_handler,
118#endif
119#ifdef CONFIG_EXT2_FS_SECURITY
120 &ext2_xattr_security_handler,
121#endif
122 NULL
123};
124
125#define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache)
126
127static inline const struct xattr_handler *
128ext2_xattr_handler(int name_index)
129{
130 const struct xattr_handler *handler = NULL;
131
132 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
133 handler = ext2_xattr_handler_map[name_index];
134 return handler;
135}
136
137static bool
138ext2_xattr_header_valid(struct ext2_xattr_header *header)
139{
140 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
141 header->h_blocks != cpu_to_le32(1))
142 return false;
143
144 return true;
145}
146
147static bool
148ext2_xattr_entry_valid(struct ext2_xattr_entry *entry,
149 char *end, size_t end_offs)
150{
151 struct ext2_xattr_entry *next;
152 size_t size;
153
154 next = EXT2_XATTR_NEXT(entry);
155 if ((char *)next >= end)
156 return false;
157
158 if (entry->e_value_block != 0)
159 return false;
160
161 size = le32_to_cpu(entry->e_value_size);
162 if (size > end_offs ||
163 le16_to_cpu(entry->e_value_offs) + size > end_offs)
164 return false;
165
166 return true;
167}
168
169static int
170ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name,
171 struct ext2_xattr_entry *entry)
172{
173 int cmp;
174
175 cmp = name_index - entry->e_name_index;
176 if (!cmp)
177 cmp = name_len - entry->e_name_len;
178 if (!cmp)
179 cmp = memcmp(name, entry->e_name, name_len);
180
181 return cmp;
182}
183
184/*
185 * ext2_xattr_get()
186 *
187 * Copy an extended attribute into the buffer
188 * provided, or compute the buffer size required.
189 * Buffer is NULL to compute the size of the buffer required.
190 *
191 * Returns a negative error number on failure, or the number of bytes
192 * used / required on success.
193 */
194int
195ext2_xattr_get(struct inode *inode, int name_index, const char *name,
196 void *buffer, size_t buffer_size)
197{
198 struct buffer_head *bh = NULL;
199 struct ext2_xattr_entry *entry;
200 size_t name_len, size;
201 char *end;
202 int error, not_found;
203 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
204
205 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
206 name_index, name, buffer, (long)buffer_size);
207
208 if (name == NULL)
209 return -EINVAL;
210 name_len = strlen(name);
211 if (name_len > 255)
212 return -ERANGE;
213
214 down_read(&EXT2_I(inode)->xattr_sem);
215 error = -ENODATA;
216 if (!EXT2_I(inode)->i_file_acl)
217 goto cleanup;
218 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
219 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
220 error = -EIO;
221 if (!bh)
222 goto cleanup;
223 ea_bdebug(bh, "b_count=%d, refcount=%d",
224 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
225 end = bh->b_data + bh->b_size;
226 if (!ext2_xattr_header_valid(HDR(bh))) {
227bad_block:
228 ext2_error(inode->i_sb, "ext2_xattr_get",
229 "inode %ld: bad block %d", inode->i_ino,
230 EXT2_I(inode)->i_file_acl);
231 error = -EIO;
232 goto cleanup;
233 }
234
235 /* find named attribute */
236 entry = FIRST_ENTRY(bh);
237 while (!IS_LAST_ENTRY(entry)) {
238 if (!ext2_xattr_entry_valid(entry, end,
239 inode->i_sb->s_blocksize))
240 goto bad_block;
241
242 not_found = ext2_xattr_cmp_entry(name_index, name_len, name,
243 entry);
244 if (!not_found)
245 goto found;
246 if (not_found < 0)
247 break;
248
249 entry = EXT2_XATTR_NEXT(entry);
250 }
251 if (ext2_xattr_cache_insert(ea_block_cache, bh))
252 ea_idebug(inode, "cache insert failed");
253 error = -ENODATA;
254 goto cleanup;
255found:
256 size = le32_to_cpu(entry->e_value_size);
257 if (ext2_xattr_cache_insert(ea_block_cache, bh))
258 ea_idebug(inode, "cache insert failed");
259 if (buffer) {
260 error = -ERANGE;
261 if (size > buffer_size)
262 goto cleanup;
263 /* return value of attribute */
264 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
265 size);
266 }
267 error = size;
268
269cleanup:
270 brelse(bh);
271 up_read(&EXT2_I(inode)->xattr_sem);
272
273 return error;
274}
275
276/*
277 * ext2_xattr_list()
278 *
279 * Copy a list of attribute names into the buffer
280 * provided, or compute the buffer size required.
281 * Buffer is NULL to compute the size of the buffer required.
282 *
283 * Returns a negative error number on failure, or the number of bytes
284 * used / required on success.
285 */
286static int
287ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
288{
289 struct inode *inode = d_inode(dentry);
290 struct buffer_head *bh = NULL;
291 struct ext2_xattr_entry *entry;
292 char *end;
293 size_t rest = buffer_size;
294 int error;
295 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
296
297 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
298 buffer, (long)buffer_size);
299
300 down_read(&EXT2_I(inode)->xattr_sem);
301 error = 0;
302 if (!EXT2_I(inode)->i_file_acl)
303 goto cleanup;
304 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
305 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
306 error = -EIO;
307 if (!bh)
308 goto cleanup;
309 ea_bdebug(bh, "b_count=%d, refcount=%d",
310 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
311 end = bh->b_data + bh->b_size;
312 if (!ext2_xattr_header_valid(HDR(bh))) {
313bad_block:
314 ext2_error(inode->i_sb, "ext2_xattr_list",
315 "inode %ld: bad block %d", inode->i_ino,
316 EXT2_I(inode)->i_file_acl);
317 error = -EIO;
318 goto cleanup;
319 }
320
321 /* check the on-disk data structure */
322 entry = FIRST_ENTRY(bh);
323 while (!IS_LAST_ENTRY(entry)) {
324 if (!ext2_xattr_entry_valid(entry, end,
325 inode->i_sb->s_blocksize))
326 goto bad_block;
327 entry = EXT2_XATTR_NEXT(entry);
328 }
329 if (ext2_xattr_cache_insert(ea_block_cache, bh))
330 ea_idebug(inode, "cache insert failed");
331
332 /* list the attribute names */
333 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
334 entry = EXT2_XATTR_NEXT(entry)) {
335 const struct xattr_handler *handler =
336 ext2_xattr_handler(entry->e_name_index);
337
338 if (handler && (!handler->list || handler->list(dentry))) {
339 const char *prefix = handler->prefix ?: handler->name;
340 size_t prefix_len = strlen(prefix);
341 size_t size = prefix_len + entry->e_name_len + 1;
342
343 if (buffer) {
344 if (size > rest) {
345 error = -ERANGE;
346 goto cleanup;
347 }
348 memcpy(buffer, prefix, prefix_len);
349 buffer += prefix_len;
350 memcpy(buffer, entry->e_name, entry->e_name_len);
351 buffer += entry->e_name_len;
352 *buffer++ = 0;
353 }
354 rest -= size;
355 }
356 }
357 error = buffer_size - rest; /* total size */
358
359cleanup:
360 brelse(bh);
361 up_read(&EXT2_I(inode)->xattr_sem);
362
363 return error;
364}
365
366/*
367 * Inode operation listxattr()
368 *
369 * d_inode(dentry)->i_mutex: don't care
370 */
371ssize_t
372ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
373{
374 return ext2_xattr_list(dentry, buffer, size);
375}
376
377/*
378 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
379 * not set, set it.
380 */
381static void ext2_xattr_update_super_block(struct super_block *sb)
382{
383 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
384 return;
385
386 spin_lock(&EXT2_SB(sb)->s_lock);
387 ext2_update_dynamic_rev(sb);
388 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
389 spin_unlock(&EXT2_SB(sb)->s_lock);
390 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
391}
392
393/*
394 * ext2_xattr_set()
395 *
396 * Create, replace or remove an extended attribute for this inode. Value
397 * is NULL to remove an existing extended attribute, and non-NULL to
398 * either replace an existing extended attribute, or create a new extended
399 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
400 * specify that an extended attribute must exist and must not exist
401 * previous to the call, respectively.
402 *
403 * Returns 0, or a negative error number on failure.
404 */
405int
406ext2_xattr_set(struct inode *inode, int name_index, const char *name,
407 const void *value, size_t value_len, int flags)
408{
409 struct super_block *sb = inode->i_sb;
410 struct buffer_head *bh = NULL;
411 struct ext2_xattr_header *header = NULL;
412 struct ext2_xattr_entry *here = NULL, *last = NULL;
413 size_t name_len, free, min_offs = sb->s_blocksize;
414 int not_found = 1, error;
415 char *end;
416
417 /*
418 * header -- Points either into bh, or to a temporarily
419 * allocated buffer.
420 * here -- The named entry found, or the place for inserting, within
421 * the block pointed to by header.
422 * last -- Points right after the last named entry within the block
423 * pointed to by header.
424 * min_offs -- The offset of the first value (values are aligned
425 * towards the end of the block).
426 * end -- Points right after the block pointed to by header.
427 */
428
429 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
430 name_index, name, value, (long)value_len);
431
432 if (value == NULL)
433 value_len = 0;
434 if (name == NULL)
435 return -EINVAL;
436 name_len = strlen(name);
437 if (name_len > 255 || value_len > sb->s_blocksize)
438 return -ERANGE;
439 down_write(&EXT2_I(inode)->xattr_sem);
440 if (EXT2_I(inode)->i_file_acl) {
441 /* The inode already has an extended attribute block. */
442 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
443 error = -EIO;
444 if (!bh)
445 goto cleanup;
446 ea_bdebug(bh, "b_count=%d, refcount=%d",
447 atomic_read(&(bh->b_count)),
448 le32_to_cpu(HDR(bh)->h_refcount));
449 header = HDR(bh);
450 end = bh->b_data + bh->b_size;
451 if (!ext2_xattr_header_valid(header)) {
452bad_block:
453 ext2_error(sb, "ext2_xattr_set",
454 "inode %ld: bad block %d", inode->i_ino,
455 EXT2_I(inode)->i_file_acl);
456 error = -EIO;
457 goto cleanup;
458 }
459 /*
460 * Find the named attribute. If not found, 'here' will point
461 * to entry where the new attribute should be inserted to
462 * maintain sorting.
463 */
464 last = FIRST_ENTRY(bh);
465 while (!IS_LAST_ENTRY(last)) {
466 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize))
467 goto bad_block;
468 if (last->e_value_size) {
469 size_t offs = le16_to_cpu(last->e_value_offs);
470 if (offs < min_offs)
471 min_offs = offs;
472 }
473 if (not_found > 0) {
474 not_found = ext2_xattr_cmp_entry(name_index,
475 name_len,
476 name, last);
477 if (not_found <= 0)
478 here = last;
479 }
480 last = EXT2_XATTR_NEXT(last);
481 }
482 if (not_found > 0)
483 here = last;
484
485 /* Check whether we have enough space left. */
486 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
487 } else {
488 /* We will use a new extended attribute block. */
489 free = sb->s_blocksize -
490 sizeof(struct ext2_xattr_header) - sizeof(__u32);
491 }
492
493 if (not_found) {
494 /* Request to remove a nonexistent attribute? */
495 error = -ENODATA;
496 if (flags & XATTR_REPLACE)
497 goto cleanup;
498 error = 0;
499 if (value == NULL)
500 goto cleanup;
501 } else {
502 /* Request to create an existing attribute? */
503 error = -EEXIST;
504 if (flags & XATTR_CREATE)
505 goto cleanup;
506 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size));
507 free += EXT2_XATTR_LEN(name_len);
508 }
509 error = -ENOSPC;
510 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
511 goto cleanup;
512
513 /* Here we know that we can set the new attribute. */
514
515 if (header) {
516 /* assert(header == HDR(bh)); */
517 lock_buffer(bh);
518 if (header->h_refcount == cpu_to_le32(1)) {
519 __u32 hash = le32_to_cpu(header->h_hash);
520
521 ea_bdebug(bh, "modifying in-place");
522 /*
523 * This must happen under buffer lock for
524 * ext2_xattr_set2() to reliably detect modified block
525 */
526 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash,
527 bh->b_blocknr);
528
529 /* keep the buffer locked while modifying it. */
530 } else {
531 int offset;
532
533 unlock_buffer(bh);
534 ea_bdebug(bh, "cloning");
535 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL);
536 error = -ENOMEM;
537 if (header == NULL)
538 goto cleanup;
539 header->h_refcount = cpu_to_le32(1);
540
541 offset = (char *)here - bh->b_data;
542 here = ENTRY((char *)header + offset);
543 offset = (char *)last - bh->b_data;
544 last = ENTRY((char *)header + offset);
545 }
546 } else {
547 /* Allocate a buffer where we construct the new block. */
548 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
549 error = -ENOMEM;
550 if (header == NULL)
551 goto cleanup;
552 end = (char *)header + sb->s_blocksize;
553 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
554 header->h_blocks = header->h_refcount = cpu_to_le32(1);
555 last = here = ENTRY(header+1);
556 }
557
558 /* Iff we are modifying the block in-place, bh is locked here. */
559
560 if (not_found) {
561 /* Insert the new name. */
562 size_t size = EXT2_XATTR_LEN(name_len);
563 size_t rest = (char *)last - (char *)here;
564 memmove((char *)here + size, here, rest);
565 memset(here, 0, size);
566 here->e_name_index = name_index;
567 here->e_name_len = name_len;
568 memcpy(here->e_name, name, name_len);
569 } else {
570 if (here->e_value_size) {
571 char *first_val = (char *)header + min_offs;
572 size_t offs = le16_to_cpu(here->e_value_offs);
573 char *val = (char *)header + offs;
574 size_t size = EXT2_XATTR_SIZE(
575 le32_to_cpu(here->e_value_size));
576
577 if (size == EXT2_XATTR_SIZE(value_len)) {
578 /* The old and the new value have the same
579 size. Just replace. */
580 here->e_value_size = cpu_to_le32(value_len);
581 memset(val + size - EXT2_XATTR_PAD, 0,
582 EXT2_XATTR_PAD); /* Clear pad bytes. */
583 memcpy(val, value, value_len);
584 goto skip_replace;
585 }
586
587 /* Remove the old value. */
588 memmove(first_val + size, first_val, val - first_val);
589 memset(first_val, 0, size);
590 here->e_value_offs = 0;
591 min_offs += size;
592
593 /* Adjust all value offsets. */
594 last = ENTRY(header+1);
595 while (!IS_LAST_ENTRY(last)) {
596 size_t o = le16_to_cpu(last->e_value_offs);
597 if (o < offs)
598 last->e_value_offs =
599 cpu_to_le16(o + size);
600 last = EXT2_XATTR_NEXT(last);
601 }
602 }
603 if (value == NULL) {
604 /* Remove the old name. */
605 size_t size = EXT2_XATTR_LEN(name_len);
606 last = ENTRY((char *)last - size);
607 memmove(here, (char*)here + size,
608 (char*)last - (char*)here);
609 memset(last, 0, size);
610 }
611 }
612
613 if (value != NULL) {
614 /* Insert the new value. */
615 here->e_value_size = cpu_to_le32(value_len);
616 if (value_len) {
617 size_t size = EXT2_XATTR_SIZE(value_len);
618 char *val = (char *)header + min_offs - size;
619 here->e_value_offs =
620 cpu_to_le16((char *)val - (char *)header);
621 memset(val + size - EXT2_XATTR_PAD, 0,
622 EXT2_XATTR_PAD); /* Clear the pad bytes. */
623 memcpy(val, value, value_len);
624 }
625 }
626
627skip_replace:
628 if (IS_LAST_ENTRY(ENTRY(header+1))) {
629 /* This block is now empty. */
630 if (bh && header == HDR(bh))
631 unlock_buffer(bh); /* we were modifying in-place. */
632 error = ext2_xattr_set2(inode, bh, NULL);
633 } else {
634 ext2_xattr_rehash(header, here);
635 if (bh && header == HDR(bh))
636 unlock_buffer(bh); /* we were modifying in-place. */
637 error = ext2_xattr_set2(inode, bh, header);
638 }
639
640cleanup:
641 if (!(bh && header == HDR(bh)))
642 kfree(header);
643 brelse(bh);
644 up_write(&EXT2_I(inode)->xattr_sem);
645
646 return error;
647}
648
649/*
650 * Second half of ext2_xattr_set(): Update the file system.
651 */
652static int
653ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
654 struct ext2_xattr_header *header)
655{
656 struct super_block *sb = inode->i_sb;
657 struct buffer_head *new_bh = NULL;
658 int error;
659 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
660
661 if (header) {
662 new_bh = ext2_xattr_cache_find(inode, header);
663 if (new_bh) {
664 /* We found an identical block in the cache. */
665 if (new_bh == old_bh) {
666 ea_bdebug(new_bh, "keeping this block");
667 } else {
668 /* The old block is released after updating
669 the inode. */
670 ea_bdebug(new_bh, "reusing block");
671
672 error = dquot_alloc_block(inode, 1);
673 if (error) {
674 unlock_buffer(new_bh);
675 goto cleanup;
676 }
677 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
678 ea_bdebug(new_bh, "refcount now=%d",
679 le32_to_cpu(HDR(new_bh)->h_refcount));
680 }
681 unlock_buffer(new_bh);
682 } else if (old_bh && header == HDR(old_bh)) {
683 /* Keep this block. No need to lock the block as we
684 don't need to change the reference count. */
685 new_bh = old_bh;
686 get_bh(new_bh);
687 ext2_xattr_cache_insert(ea_block_cache, new_bh);
688 } else {
689 /* We need to allocate a new block */
690 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
691 EXT2_I(inode)->i_block_group);
692 int block = ext2_new_block(inode, goal, &error);
693 if (error)
694 goto cleanup;
695 ea_idebug(inode, "creating block %d", block);
696
697 new_bh = sb_getblk(sb, block);
698 if (unlikely(!new_bh)) {
699 ext2_free_blocks(inode, block, 1);
700 mark_inode_dirty(inode);
701 error = -ENOMEM;
702 goto cleanup;
703 }
704 lock_buffer(new_bh);
705 memcpy(new_bh->b_data, header, new_bh->b_size);
706 set_buffer_uptodate(new_bh);
707 unlock_buffer(new_bh);
708 ext2_xattr_cache_insert(ea_block_cache, new_bh);
709
710 ext2_xattr_update_super_block(sb);
711 }
712 mark_buffer_dirty(new_bh);
713 if (IS_SYNC(inode)) {
714 sync_dirty_buffer(new_bh);
715 error = -EIO;
716 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
717 goto cleanup;
718 }
719 }
720
721 /* Update the inode. */
722 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
723 inode->i_ctime = current_time(inode);
724 if (IS_SYNC(inode)) {
725 error = sync_inode_metadata(inode, 1);
726 /* In case sync failed due to ENOSPC the inode was actually
727 * written (only some dirty data were not) so we just proceed
728 * as if nothing happened and cleanup the unused block */
729 if (error && error != -ENOSPC) {
730 if (new_bh && new_bh != old_bh) {
731 dquot_free_block_nodirty(inode, 1);
732 mark_inode_dirty(inode);
733 }
734 goto cleanup;
735 }
736 } else
737 mark_inode_dirty(inode);
738
739 error = 0;
740 if (old_bh && old_bh != new_bh) {
741 /*
742 * If there was an old block and we are no longer using it,
743 * release the old block.
744 */
745 lock_buffer(old_bh);
746 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
747 __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash);
748
749 /*
750 * This must happen under buffer lock for
751 * ext2_xattr_set2() to reliably detect freed block
752 */
753 mb_cache_entry_delete(ea_block_cache, hash,
754 old_bh->b_blocknr);
755 /* Free the old block. */
756 ea_bdebug(old_bh, "freeing");
757 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
758 mark_inode_dirty(inode);
759 /* We let our caller release old_bh, so we
760 * need to duplicate the buffer before. */
761 get_bh(old_bh);
762 bforget(old_bh);
763 } else {
764 /* Decrement the refcount only. */
765 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
766 dquot_free_block_nodirty(inode, 1);
767 mark_inode_dirty(inode);
768 mark_buffer_dirty(old_bh);
769 ea_bdebug(old_bh, "refcount now=%d",
770 le32_to_cpu(HDR(old_bh)->h_refcount));
771 }
772 unlock_buffer(old_bh);
773 }
774
775cleanup:
776 brelse(new_bh);
777
778 return error;
779}
780
781/*
782 * ext2_xattr_delete_inode()
783 *
784 * Free extended attribute resources associated with this inode. This
785 * is called immediately before an inode is freed.
786 */
787void
788ext2_xattr_delete_inode(struct inode *inode)
789{
790 struct buffer_head *bh = NULL;
791 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
792
793 down_write(&EXT2_I(inode)->xattr_sem);
794 if (!EXT2_I(inode)->i_file_acl)
795 goto cleanup;
796
797 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) {
798 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
799 "inode %ld: xattr block %d is out of data blocks range",
800 inode->i_ino, EXT2_I(inode)->i_file_acl);
801 goto cleanup;
802 }
803
804 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
805 if (!bh) {
806 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
807 "inode %ld: block %d read error", inode->i_ino,
808 EXT2_I(inode)->i_file_acl);
809 goto cleanup;
810 }
811 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
812 if (!ext2_xattr_header_valid(HDR(bh))) {
813 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
814 "inode %ld: bad block %d", inode->i_ino,
815 EXT2_I(inode)->i_file_acl);
816 goto cleanup;
817 }
818 lock_buffer(bh);
819 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
820 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
821
822 /*
823 * This must happen under buffer lock for ext2_xattr_set2() to
824 * reliably detect freed block
825 */
826 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash,
827 bh->b_blocknr);
828 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
829 get_bh(bh);
830 bforget(bh);
831 unlock_buffer(bh);
832 } else {
833 le32_add_cpu(&HDR(bh)->h_refcount, -1);
834 ea_bdebug(bh, "refcount now=%d",
835 le32_to_cpu(HDR(bh)->h_refcount));
836 unlock_buffer(bh);
837 mark_buffer_dirty(bh);
838 if (IS_SYNC(inode))
839 sync_dirty_buffer(bh);
840 dquot_free_block_nodirty(inode, 1);
841 }
842 EXT2_I(inode)->i_file_acl = 0;
843
844cleanup:
845 brelse(bh);
846 up_write(&EXT2_I(inode)->xattr_sem);
847}
848
849/*
850 * ext2_xattr_cache_insert()
851 *
852 * Create a new entry in the extended attribute cache, and insert
853 * it unless such an entry is already in the cache.
854 *
855 * Returns 0, or a negative error number on failure.
856 */
857static int
858ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)
859{
860 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
861 int error;
862
863 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr,
864 true);
865 if (error) {
866 if (error == -EBUSY) {
867 ea_bdebug(bh, "already in cache (%d cache entries)",
868 atomic_read(&ext2_xattr_cache->c_entry_count));
869 error = 0;
870 }
871 } else
872 ea_bdebug(bh, "inserting [%x]", (int)hash);
873 return error;
874}
875
876/*
877 * ext2_xattr_cmp()
878 *
879 * Compare two extended attribute blocks for equality.
880 *
881 * Returns 0 if the blocks are equal, 1 if they differ, and
882 * a negative error number on errors.
883 */
884static int
885ext2_xattr_cmp(struct ext2_xattr_header *header1,
886 struct ext2_xattr_header *header2)
887{
888 struct ext2_xattr_entry *entry1, *entry2;
889
890 entry1 = ENTRY(header1+1);
891 entry2 = ENTRY(header2+1);
892 while (!IS_LAST_ENTRY(entry1)) {
893 if (IS_LAST_ENTRY(entry2))
894 return 1;
895 if (entry1->e_hash != entry2->e_hash ||
896 entry1->e_name_index != entry2->e_name_index ||
897 entry1->e_name_len != entry2->e_name_len ||
898 entry1->e_value_size != entry2->e_value_size ||
899 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
900 return 1;
901 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
902 return -EIO;
903 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
904 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
905 le32_to_cpu(entry1->e_value_size)))
906 return 1;
907
908 entry1 = EXT2_XATTR_NEXT(entry1);
909 entry2 = EXT2_XATTR_NEXT(entry2);
910 }
911 if (!IS_LAST_ENTRY(entry2))
912 return 1;
913 return 0;
914}
915
916/*
917 * ext2_xattr_cache_find()
918 *
919 * Find an identical extended attribute block.
920 *
921 * Returns a locked buffer head to the block found, or NULL if such
922 * a block was not found or an error occurred.
923 */
924static struct buffer_head *
925ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
926{
927 __u32 hash = le32_to_cpu(header->h_hash);
928 struct mb_cache_entry *ce;
929 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
930
931 if (!header->h_hash)
932 return NULL; /* never share */
933 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
934again:
935 ce = mb_cache_entry_find_first(ea_block_cache, hash);
936 while (ce) {
937 struct buffer_head *bh;
938
939 bh = sb_bread(inode->i_sb, ce->e_value);
940 if (!bh) {
941 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
942 "inode %ld: block %ld read error",
943 inode->i_ino, (unsigned long) ce->e_value);
944 } else {
945 lock_buffer(bh);
946 /*
947 * We have to be careful about races with freeing or
948 * rehashing of xattr block. Once we hold buffer lock
949 * xattr block's state is stable so we can check
950 * whether the block got freed / rehashed or not.
951 * Since we unhash mbcache entry under buffer lock when
952 * freeing / rehashing xattr block, checking whether
953 * entry is still hashed is reliable.
954 */
955 if (hlist_bl_unhashed(&ce->e_hash_list)) {
956 mb_cache_entry_put(ea_block_cache, ce);
957 unlock_buffer(bh);
958 brelse(bh);
959 goto again;
960 } else if (le32_to_cpu(HDR(bh)->h_refcount) >
961 EXT2_XATTR_REFCOUNT_MAX) {
962 ea_idebug(inode, "block %ld refcount %d>%d",
963 (unsigned long) ce->e_value,
964 le32_to_cpu(HDR(bh)->h_refcount),
965 EXT2_XATTR_REFCOUNT_MAX);
966 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
967 ea_bdebug(bh, "b_count=%d",
968 atomic_read(&(bh->b_count)));
969 mb_cache_entry_touch(ea_block_cache, ce);
970 mb_cache_entry_put(ea_block_cache, ce);
971 return bh;
972 }
973 unlock_buffer(bh);
974 brelse(bh);
975 }
976 ce = mb_cache_entry_find_next(ea_block_cache, ce);
977 }
978 return NULL;
979}
980
981#define NAME_HASH_SHIFT 5
982#define VALUE_HASH_SHIFT 16
983
984/*
985 * ext2_xattr_hash_entry()
986 *
987 * Compute the hash of an extended attribute.
988 */
989static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
990 struct ext2_xattr_entry *entry)
991{
992 __u32 hash = 0;
993 char *name = entry->e_name;
994 int n;
995
996 for (n=0; n < entry->e_name_len; n++) {
997 hash = (hash << NAME_HASH_SHIFT) ^
998 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
999 *name++;
1000 }
1001
1002 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1003 __le32 *value = (__le32 *)((char *)header +
1004 le16_to_cpu(entry->e_value_offs));
1005 for (n = (le32_to_cpu(entry->e_value_size) +
1006 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
1007 hash = (hash << VALUE_HASH_SHIFT) ^
1008 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1009 le32_to_cpu(*value++);
1010 }
1011 }
1012 entry->e_hash = cpu_to_le32(hash);
1013}
1014
1015#undef NAME_HASH_SHIFT
1016#undef VALUE_HASH_SHIFT
1017
1018#define BLOCK_HASH_SHIFT 16
1019
1020/*
1021 * ext2_xattr_rehash()
1022 *
1023 * Re-compute the extended attribute hash value after an entry has changed.
1024 */
1025static void ext2_xattr_rehash(struct ext2_xattr_header *header,
1026 struct ext2_xattr_entry *entry)
1027{
1028 struct ext2_xattr_entry *here;
1029 __u32 hash = 0;
1030
1031 ext2_xattr_hash_entry(header, entry);
1032 here = ENTRY(header+1);
1033 while (!IS_LAST_ENTRY(here)) {
1034 if (!here->e_hash) {
1035 /* Block is not shared if an entry's hash value == 0 */
1036 hash = 0;
1037 break;
1038 }
1039 hash = (hash << BLOCK_HASH_SHIFT) ^
1040 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1041 le32_to_cpu(here->e_hash);
1042 here = EXT2_XATTR_NEXT(here);
1043 }
1044 header->h_hash = cpu_to_le32(hash);
1045}
1046
1047#undef BLOCK_HASH_SHIFT
1048
1049#define HASH_BUCKET_BITS 10
1050
1051struct mb_cache *ext2_xattr_create_cache(void)
1052{
1053 return mb_cache_create(HASH_BUCKET_BITS);
1054}
1055
1056void ext2_xattr_destroy_cache(struct mb_cache *cache)
1057{
1058 if (cache)
1059 mb_cache_destroy(cache);
1060}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext2/xattr.c
4 *
5 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>
6 *
7 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
8 * Extended attributes for symlinks and special files added per
9 * suggestion of Luka Renko <luka.renko@hermes.si>.
10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
11 * Red Hat Inc.
12 *
13 */
14
15/*
16 * Extended attributes are stored on disk blocks allocated outside of
17 * any inode. The i_file_acl field is then made to point to this allocated
18 * block. If all extended attributes of an inode are identical, these
19 * inodes may share the same extended attribute block. Such situations
20 * are automatically detected by keeping a cache of recent attribute block
21 * numbers and hashes over the block's contents in memory.
22 *
23 *
24 * Extended attribute block layout:
25 *
26 * +------------------+
27 * | header |
28 * | entry 1 | |
29 * | entry 2 | | growing downwards
30 * | entry 3 | v
31 * | four null bytes |
32 * | . . . |
33 * | value 1 | ^
34 * | value 3 | | growing upwards
35 * | value 2 | |
36 * +------------------+
37 *
38 * The block header is followed by multiple entry descriptors. These entry
39 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD
40 * byte boundaries. The entry descriptors are sorted by attribute name,
41 * so that two extended attribute blocks can be compared efficiently.
42 *
43 * Attribute values are aligned to the end of the block, stored in
44 * no specific order. They are also padded to EXT2_XATTR_PAD byte
45 * boundaries. No additional gaps are left between them.
46 *
47 * Locking strategy
48 * ----------------
49 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem.
50 * EA blocks are only changed if they are exclusive to an inode, so
51 * holding xattr_sem also means that nothing but the EA block's reference
52 * count will change. Multiple writers to an EA block are synchronized
53 * by the bh lock. No more than a single bh lock is held at any time
54 * to avoid deadlocks.
55 */
56
57#include <linux/buffer_head.h>
58#include <linux/init.h>
59#include <linux/printk.h>
60#include <linux/slab.h>
61#include <linux/mbcache.h>
62#include <linux/quotaops.h>
63#include <linux/rwsem.h>
64#include <linux/security.h>
65#include "ext2.h"
66#include "xattr.h"
67#include "acl.h"
68
69#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))
70#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))
71#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)
72#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
73
74#ifdef EXT2_XATTR_DEBUG
75# define ea_idebug(inode, f...) do { \
76 printk(KERN_DEBUG "inode %s:%ld: ", \
77 inode->i_sb->s_id, inode->i_ino); \
78 printk(f); \
79 printk("\n"); \
80 } while (0)
81# define ea_bdebug(bh, f...) do { \
82 printk(KERN_DEBUG "block %pg:%lu: ", \
83 bh->b_bdev, (unsigned long) bh->b_blocknr); \
84 printk(f); \
85 printk("\n"); \
86 } while (0)
87#else
88# define ea_idebug(inode, f...) no_printk(f)
89# define ea_bdebug(bh, f...) no_printk(f)
90#endif
91
92static int ext2_xattr_set2(struct inode *, struct buffer_head *,
93 struct ext2_xattr_header *);
94
95static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
96static struct buffer_head *ext2_xattr_cache_find(struct inode *,
97 struct ext2_xattr_header *);
98static void ext2_xattr_rehash(struct ext2_xattr_header *,
99 struct ext2_xattr_entry *);
100
101static const struct xattr_handler *ext2_xattr_handler_map[] = {
102 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
103#ifdef CONFIG_EXT2_FS_POSIX_ACL
104 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler,
105 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
106#endif
107 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
108#ifdef CONFIG_EXT2_FS_SECURITY
109 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
110#endif
111};
112
113const struct xattr_handler *ext2_xattr_handlers[] = {
114 &ext2_xattr_user_handler,
115 &ext2_xattr_trusted_handler,
116#ifdef CONFIG_EXT2_FS_POSIX_ACL
117 &posix_acl_access_xattr_handler,
118 &posix_acl_default_xattr_handler,
119#endif
120#ifdef CONFIG_EXT2_FS_SECURITY
121 &ext2_xattr_security_handler,
122#endif
123 NULL
124};
125
126#define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache)
127
128static inline const struct xattr_handler *
129ext2_xattr_handler(int name_index)
130{
131 const struct xattr_handler *handler = NULL;
132
133 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
134 handler = ext2_xattr_handler_map[name_index];
135 return handler;
136}
137
138static bool
139ext2_xattr_header_valid(struct ext2_xattr_header *header)
140{
141 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
142 header->h_blocks != cpu_to_le32(1))
143 return false;
144
145 return true;
146}
147
148static bool
149ext2_xattr_entry_valid(struct ext2_xattr_entry *entry,
150 char *end, size_t end_offs)
151{
152 struct ext2_xattr_entry *next;
153 size_t size;
154
155 next = EXT2_XATTR_NEXT(entry);
156 if ((char *)next >= end)
157 return false;
158
159 if (entry->e_value_block != 0)
160 return false;
161
162 size = le32_to_cpu(entry->e_value_size);
163 if (size > end_offs ||
164 le16_to_cpu(entry->e_value_offs) + size > end_offs)
165 return false;
166
167 return true;
168}
169
170static int
171ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name,
172 struct ext2_xattr_entry *entry)
173{
174 int cmp;
175
176 cmp = name_index - entry->e_name_index;
177 if (!cmp)
178 cmp = name_len - entry->e_name_len;
179 if (!cmp)
180 cmp = memcmp(name, entry->e_name, name_len);
181
182 return cmp;
183}
184
185/*
186 * ext2_xattr_get()
187 *
188 * Copy an extended attribute into the buffer
189 * provided, or compute the buffer size required.
190 * Buffer is NULL to compute the size of the buffer required.
191 *
192 * Returns a negative error number on failure, or the number of bytes
193 * used / required on success.
194 */
195int
196ext2_xattr_get(struct inode *inode, int name_index, const char *name,
197 void *buffer, size_t buffer_size)
198{
199 struct buffer_head *bh = NULL;
200 struct ext2_xattr_entry *entry;
201 size_t name_len, size;
202 char *end;
203 int error, not_found;
204 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
205
206 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
207 name_index, name, buffer, (long)buffer_size);
208
209 if (name == NULL)
210 return -EINVAL;
211 name_len = strlen(name);
212 if (name_len > 255)
213 return -ERANGE;
214
215 down_read(&EXT2_I(inode)->xattr_sem);
216 error = -ENODATA;
217 if (!EXT2_I(inode)->i_file_acl)
218 goto cleanup;
219 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
220 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
221 error = -EIO;
222 if (!bh)
223 goto cleanup;
224 ea_bdebug(bh, "b_count=%d, refcount=%d",
225 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
226 end = bh->b_data + bh->b_size;
227 if (!ext2_xattr_header_valid(HDR(bh))) {
228bad_block:
229 ext2_error(inode->i_sb, "ext2_xattr_get",
230 "inode %ld: bad block %d", inode->i_ino,
231 EXT2_I(inode)->i_file_acl);
232 error = -EIO;
233 goto cleanup;
234 }
235
236 /* find named attribute */
237 entry = FIRST_ENTRY(bh);
238 while (!IS_LAST_ENTRY(entry)) {
239 if (!ext2_xattr_entry_valid(entry, end,
240 inode->i_sb->s_blocksize))
241 goto bad_block;
242
243 not_found = ext2_xattr_cmp_entry(name_index, name_len, name,
244 entry);
245 if (!not_found)
246 goto found;
247 if (not_found < 0)
248 break;
249
250 entry = EXT2_XATTR_NEXT(entry);
251 }
252 if (ext2_xattr_cache_insert(ea_block_cache, bh))
253 ea_idebug(inode, "cache insert failed");
254 error = -ENODATA;
255 goto cleanup;
256found:
257 size = le32_to_cpu(entry->e_value_size);
258 if (ext2_xattr_cache_insert(ea_block_cache, bh))
259 ea_idebug(inode, "cache insert failed");
260 if (buffer) {
261 error = -ERANGE;
262 if (size > buffer_size)
263 goto cleanup;
264 /* return value of attribute */
265 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
266 size);
267 }
268 error = size;
269
270cleanup:
271 brelse(bh);
272 up_read(&EXT2_I(inode)->xattr_sem);
273
274 return error;
275}
276
277/*
278 * ext2_xattr_list()
279 *
280 * Copy a list of attribute names into the buffer
281 * provided, or compute the buffer size required.
282 * Buffer is NULL to compute the size of the buffer required.
283 *
284 * Returns a negative error number on failure, or the number of bytes
285 * used / required on success.
286 */
287static int
288ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
289{
290 struct inode *inode = d_inode(dentry);
291 struct buffer_head *bh = NULL;
292 struct ext2_xattr_entry *entry;
293 char *end;
294 size_t rest = buffer_size;
295 int error;
296 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
297
298 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
299 buffer, (long)buffer_size);
300
301 down_read(&EXT2_I(inode)->xattr_sem);
302 error = 0;
303 if (!EXT2_I(inode)->i_file_acl)
304 goto cleanup;
305 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
306 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
307 error = -EIO;
308 if (!bh)
309 goto cleanup;
310 ea_bdebug(bh, "b_count=%d, refcount=%d",
311 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
312 end = bh->b_data + bh->b_size;
313 if (!ext2_xattr_header_valid(HDR(bh))) {
314bad_block:
315 ext2_error(inode->i_sb, "ext2_xattr_list",
316 "inode %ld: bad block %d", inode->i_ino,
317 EXT2_I(inode)->i_file_acl);
318 error = -EIO;
319 goto cleanup;
320 }
321
322 /* check the on-disk data structure */
323 entry = FIRST_ENTRY(bh);
324 while (!IS_LAST_ENTRY(entry)) {
325 if (!ext2_xattr_entry_valid(entry, end,
326 inode->i_sb->s_blocksize))
327 goto bad_block;
328 entry = EXT2_XATTR_NEXT(entry);
329 }
330 if (ext2_xattr_cache_insert(ea_block_cache, bh))
331 ea_idebug(inode, "cache insert failed");
332
333 /* list the attribute names */
334 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
335 entry = EXT2_XATTR_NEXT(entry)) {
336 const struct xattr_handler *handler =
337 ext2_xattr_handler(entry->e_name_index);
338
339 if (handler && (!handler->list || handler->list(dentry))) {
340 const char *prefix = handler->prefix ?: handler->name;
341 size_t prefix_len = strlen(prefix);
342 size_t size = prefix_len + entry->e_name_len + 1;
343
344 if (buffer) {
345 if (size > rest) {
346 error = -ERANGE;
347 goto cleanup;
348 }
349 memcpy(buffer, prefix, prefix_len);
350 buffer += prefix_len;
351 memcpy(buffer, entry->e_name, entry->e_name_len);
352 buffer += entry->e_name_len;
353 *buffer++ = 0;
354 }
355 rest -= size;
356 }
357 }
358 error = buffer_size - rest; /* total size */
359
360cleanup:
361 brelse(bh);
362 up_read(&EXT2_I(inode)->xattr_sem);
363
364 return error;
365}
366
367/*
368 * Inode operation listxattr()
369 *
370 * d_inode(dentry)->i_mutex: don't care
371 */
372ssize_t
373ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
374{
375 return ext2_xattr_list(dentry, buffer, size);
376}
377
378/*
379 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
380 * not set, set it.
381 */
382static void ext2_xattr_update_super_block(struct super_block *sb)
383{
384 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
385 return;
386
387 spin_lock(&EXT2_SB(sb)->s_lock);
388 ext2_update_dynamic_rev(sb);
389 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
390 spin_unlock(&EXT2_SB(sb)->s_lock);
391 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
392}
393
394/*
395 * ext2_xattr_set()
396 *
397 * Create, replace or remove an extended attribute for this inode. Value
398 * is NULL to remove an existing extended attribute, and non-NULL to
399 * either replace an existing extended attribute, or create a new extended
400 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
401 * specify that an extended attribute must exist and must not exist
402 * previous to the call, respectively.
403 *
404 * Returns 0, or a negative error number on failure.
405 */
406int
407ext2_xattr_set(struct inode *inode, int name_index, const char *name,
408 const void *value, size_t value_len, int flags)
409{
410 struct super_block *sb = inode->i_sb;
411 struct buffer_head *bh = NULL;
412 struct ext2_xattr_header *header = NULL;
413 struct ext2_xattr_entry *here = NULL, *last = NULL;
414 size_t name_len, free, min_offs = sb->s_blocksize;
415 int not_found = 1, error;
416 char *end;
417
418 /*
419 * header -- Points either into bh, or to a temporarily
420 * allocated buffer.
421 * here -- The named entry found, or the place for inserting, within
422 * the block pointed to by header.
423 * last -- Points right after the last named entry within the block
424 * pointed to by header.
425 * min_offs -- The offset of the first value (values are aligned
426 * towards the end of the block).
427 * end -- Points right after the block pointed to by header.
428 */
429
430 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
431 name_index, name, value, (long)value_len);
432
433 if (value == NULL)
434 value_len = 0;
435 if (name == NULL)
436 return -EINVAL;
437 name_len = strlen(name);
438 if (name_len > 255 || value_len > sb->s_blocksize)
439 return -ERANGE;
440 error = dquot_initialize(inode);
441 if (error)
442 return error;
443 down_write(&EXT2_I(inode)->xattr_sem);
444 if (EXT2_I(inode)->i_file_acl) {
445 /* The inode already has an extended attribute block. */
446 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
447 error = -EIO;
448 if (!bh)
449 goto cleanup;
450 ea_bdebug(bh, "b_count=%d, refcount=%d",
451 atomic_read(&(bh->b_count)),
452 le32_to_cpu(HDR(bh)->h_refcount));
453 header = HDR(bh);
454 end = bh->b_data + bh->b_size;
455 if (!ext2_xattr_header_valid(header)) {
456bad_block:
457 ext2_error(sb, "ext2_xattr_set",
458 "inode %ld: bad block %d", inode->i_ino,
459 EXT2_I(inode)->i_file_acl);
460 error = -EIO;
461 goto cleanup;
462 }
463 /*
464 * Find the named attribute. If not found, 'here' will point
465 * to entry where the new attribute should be inserted to
466 * maintain sorting.
467 */
468 last = FIRST_ENTRY(bh);
469 while (!IS_LAST_ENTRY(last)) {
470 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize))
471 goto bad_block;
472 if (last->e_value_size) {
473 size_t offs = le16_to_cpu(last->e_value_offs);
474 if (offs < min_offs)
475 min_offs = offs;
476 }
477 if (not_found > 0) {
478 not_found = ext2_xattr_cmp_entry(name_index,
479 name_len,
480 name, last);
481 if (not_found <= 0)
482 here = last;
483 }
484 last = EXT2_XATTR_NEXT(last);
485 }
486 if (not_found > 0)
487 here = last;
488
489 /* Check whether we have enough space left. */
490 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
491 } else {
492 /* We will use a new extended attribute block. */
493 free = sb->s_blocksize -
494 sizeof(struct ext2_xattr_header) - sizeof(__u32);
495 }
496
497 if (not_found) {
498 /* Request to remove a nonexistent attribute? */
499 error = -ENODATA;
500 if (flags & XATTR_REPLACE)
501 goto cleanup;
502 error = 0;
503 if (value == NULL)
504 goto cleanup;
505 } else {
506 /* Request to create an existing attribute? */
507 error = -EEXIST;
508 if (flags & XATTR_CREATE)
509 goto cleanup;
510 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size));
511 free += EXT2_XATTR_LEN(name_len);
512 }
513 error = -ENOSPC;
514 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
515 goto cleanup;
516
517 /* Here we know that we can set the new attribute. */
518
519 if (header) {
520 /* assert(header == HDR(bh)); */
521 lock_buffer(bh);
522 if (header->h_refcount == cpu_to_le32(1)) {
523 __u32 hash = le32_to_cpu(header->h_hash);
524
525 ea_bdebug(bh, "modifying in-place");
526 /*
527 * This must happen under buffer lock for
528 * ext2_xattr_set2() to reliably detect modified block
529 */
530 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash,
531 bh->b_blocknr);
532
533 /* keep the buffer locked while modifying it. */
534 } else {
535 int offset;
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 }
550 } else {
551 /* Allocate a buffer where we construct the new block. */
552 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
553 error = -ENOMEM;
554 if (header == NULL)
555 goto cleanup;
556 end = (char *)header + sb->s_blocksize;
557 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
558 header->h_blocks = header->h_refcount = cpu_to_le32(1);
559 last = here = ENTRY(header+1);
560 }
561
562 /* Iff we are modifying the block in-place, bh is locked here. */
563
564 if (not_found) {
565 /* Insert the new name. */
566 size_t size = EXT2_XATTR_LEN(name_len);
567 size_t rest = (char *)last - (char *)here;
568 memmove((char *)here + size, here, rest);
569 memset(here, 0, size);
570 here->e_name_index = name_index;
571 here->e_name_len = name_len;
572 memcpy(here->e_name, name, name_len);
573 } else {
574 if (here->e_value_size) {
575 char *first_val = (char *)header + min_offs;
576 size_t offs = le16_to_cpu(here->e_value_offs);
577 char *val = (char *)header + offs;
578 size_t size = EXT2_XATTR_SIZE(
579 le32_to_cpu(here->e_value_size));
580
581 if (size == EXT2_XATTR_SIZE(value_len)) {
582 /* The old and the new value have the same
583 size. Just replace. */
584 here->e_value_size = cpu_to_le32(value_len);
585 memset(val + size - EXT2_XATTR_PAD, 0,
586 EXT2_XATTR_PAD); /* Clear pad bytes. */
587 memcpy(val, value, value_len);
588 goto skip_replace;
589 }
590
591 /* Remove the old value. */
592 memmove(first_val + size, first_val, val - first_val);
593 memset(first_val, 0, size);
594 min_offs += size;
595
596 /* Adjust all value offsets. */
597 last = ENTRY(header+1);
598 while (!IS_LAST_ENTRY(last)) {
599 size_t o = le16_to_cpu(last->e_value_offs);
600 if (o < offs)
601 last->e_value_offs =
602 cpu_to_le16(o + size);
603 last = EXT2_XATTR_NEXT(last);
604 }
605
606 here->e_value_offs = 0;
607 }
608 if (value == NULL) {
609 /* Remove the old name. */
610 size_t size = EXT2_XATTR_LEN(name_len);
611 last = ENTRY((char *)last - size);
612 memmove(here, (char*)here + size,
613 (char*)last - (char*)here);
614 memset(last, 0, size);
615 }
616 }
617
618 if (value != NULL) {
619 /* Insert the new value. */
620 here->e_value_size = cpu_to_le32(value_len);
621 if (value_len) {
622 size_t size = EXT2_XATTR_SIZE(value_len);
623 char *val = (char *)header + min_offs - size;
624 here->e_value_offs =
625 cpu_to_le16((char *)val - (char *)header);
626 memset(val + size - EXT2_XATTR_PAD, 0,
627 EXT2_XATTR_PAD); /* Clear the pad bytes. */
628 memcpy(val, value, value_len);
629 }
630 }
631
632skip_replace:
633 if (IS_LAST_ENTRY(ENTRY(header+1))) {
634 /* This block is now empty. */
635 if (bh && header == HDR(bh))
636 unlock_buffer(bh); /* we were modifying in-place. */
637 error = ext2_xattr_set2(inode, bh, NULL);
638 } else {
639 ext2_xattr_rehash(header, here);
640 if (bh && header == HDR(bh))
641 unlock_buffer(bh); /* we were modifying in-place. */
642 error = ext2_xattr_set2(inode, bh, header);
643 }
644
645cleanup:
646 if (!(bh && header == HDR(bh)))
647 kfree(header);
648 brelse(bh);
649 up_write(&EXT2_I(inode)->xattr_sem);
650
651 return error;
652}
653
654/*
655 * Second half of ext2_xattr_set(): Update the file system.
656 */
657static int
658ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
659 struct ext2_xattr_header *header)
660{
661 struct super_block *sb = inode->i_sb;
662 struct buffer_head *new_bh = NULL;
663 int error;
664 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
665
666 if (header) {
667 new_bh = ext2_xattr_cache_find(inode, header);
668 if (new_bh) {
669 /* We found an identical block in the cache. */
670 if (new_bh == old_bh) {
671 ea_bdebug(new_bh, "keeping this block");
672 } else {
673 /* The old block is released after updating
674 the inode. */
675 ea_bdebug(new_bh, "reusing block");
676
677 error = dquot_alloc_block(inode, 1);
678 if (error) {
679 unlock_buffer(new_bh);
680 goto cleanup;
681 }
682 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
683 ea_bdebug(new_bh, "refcount now=%d",
684 le32_to_cpu(HDR(new_bh)->h_refcount));
685 }
686 unlock_buffer(new_bh);
687 } else if (old_bh && header == HDR(old_bh)) {
688 /* Keep this block. No need to lock the block as we
689 don't need to change the reference count. */
690 new_bh = old_bh;
691 get_bh(new_bh);
692 ext2_xattr_cache_insert(ea_block_cache, new_bh);
693 } else {
694 /* We need to allocate a new block */
695 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
696 EXT2_I(inode)->i_block_group);
697 int block = ext2_new_block(inode, goal, &error);
698 if (error)
699 goto cleanup;
700 ea_idebug(inode, "creating block %d", block);
701
702 new_bh = sb_getblk(sb, block);
703 if (unlikely(!new_bh)) {
704 ext2_free_blocks(inode, block, 1);
705 mark_inode_dirty(inode);
706 error = -ENOMEM;
707 goto cleanup;
708 }
709 lock_buffer(new_bh);
710 memcpy(new_bh->b_data, header, new_bh->b_size);
711 set_buffer_uptodate(new_bh);
712 unlock_buffer(new_bh);
713 ext2_xattr_cache_insert(ea_block_cache, new_bh);
714
715 ext2_xattr_update_super_block(sb);
716 }
717 mark_buffer_dirty(new_bh);
718 if (IS_SYNC(inode)) {
719 sync_dirty_buffer(new_bh);
720 error = -EIO;
721 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
722 goto cleanup;
723 }
724 }
725
726 /* Update the inode. */
727 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
728 inode->i_ctime = current_time(inode);
729 if (IS_SYNC(inode)) {
730 error = sync_inode_metadata(inode, 1);
731 /* In case sync failed due to ENOSPC the inode was actually
732 * written (only some dirty data were not) so we just proceed
733 * as if nothing happened and cleanup the unused block */
734 if (error && error != -ENOSPC) {
735 if (new_bh && new_bh != old_bh) {
736 dquot_free_block_nodirty(inode, 1);
737 mark_inode_dirty(inode);
738 }
739 goto cleanup;
740 }
741 } else
742 mark_inode_dirty(inode);
743
744 error = 0;
745 if (old_bh && old_bh != new_bh) {
746 /*
747 * If there was an old block and we are no longer using it,
748 * release the old block.
749 */
750 lock_buffer(old_bh);
751 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
752 __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash);
753
754 /*
755 * This must happen under buffer lock for
756 * ext2_xattr_set2() to reliably detect freed block
757 */
758 mb_cache_entry_delete(ea_block_cache, hash,
759 old_bh->b_blocknr);
760 /* Free the old block. */
761 ea_bdebug(old_bh, "freeing");
762 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
763 mark_inode_dirty(inode);
764 /* We let our caller release old_bh, so we
765 * need to duplicate the buffer before. */
766 get_bh(old_bh);
767 bforget(old_bh);
768 } else {
769 /* Decrement the refcount only. */
770 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
771 dquot_free_block_nodirty(inode, 1);
772 mark_inode_dirty(inode);
773 mark_buffer_dirty(old_bh);
774 ea_bdebug(old_bh, "refcount now=%d",
775 le32_to_cpu(HDR(old_bh)->h_refcount));
776 }
777 unlock_buffer(old_bh);
778 }
779
780cleanup:
781 brelse(new_bh);
782
783 return error;
784}
785
786/*
787 * ext2_xattr_delete_inode()
788 *
789 * Free extended attribute resources associated with this inode. This
790 * is called immediately before an inode is freed.
791 */
792void
793ext2_xattr_delete_inode(struct inode *inode)
794{
795 struct buffer_head *bh = NULL;
796 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
797
798 /*
799 * We are the only ones holding inode reference. The xattr_sem should
800 * better be unlocked! We could as well just not acquire xattr_sem at
801 * all but this makes the code more futureproof. OTOH we need trylock
802 * here to avoid false-positive warning from lockdep about reclaim
803 * circular dependency.
804 */
805 if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem)))
806 return;
807 if (!EXT2_I(inode)->i_file_acl)
808 goto cleanup;
809
810 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) {
811 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
812 "inode %ld: xattr block %d is out of data blocks range",
813 inode->i_ino, EXT2_I(inode)->i_file_acl);
814 goto cleanup;
815 }
816
817 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
818 if (!bh) {
819 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
820 "inode %ld: block %d read error", inode->i_ino,
821 EXT2_I(inode)->i_file_acl);
822 goto cleanup;
823 }
824 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
825 if (!ext2_xattr_header_valid(HDR(bh))) {
826 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
827 "inode %ld: bad block %d", inode->i_ino,
828 EXT2_I(inode)->i_file_acl);
829 goto cleanup;
830 }
831 lock_buffer(bh);
832 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
833 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
834
835 /*
836 * This must happen under buffer lock for ext2_xattr_set2() to
837 * reliably detect freed block
838 */
839 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash,
840 bh->b_blocknr);
841 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
842 get_bh(bh);
843 bforget(bh);
844 unlock_buffer(bh);
845 } else {
846 le32_add_cpu(&HDR(bh)->h_refcount, -1);
847 ea_bdebug(bh, "refcount now=%d",
848 le32_to_cpu(HDR(bh)->h_refcount));
849 unlock_buffer(bh);
850 mark_buffer_dirty(bh);
851 if (IS_SYNC(inode))
852 sync_dirty_buffer(bh);
853 dquot_free_block_nodirty(inode, 1);
854 }
855 EXT2_I(inode)->i_file_acl = 0;
856
857cleanup:
858 brelse(bh);
859 up_write(&EXT2_I(inode)->xattr_sem);
860}
861
862/*
863 * ext2_xattr_cache_insert()
864 *
865 * Create a new entry in the extended attribute cache, and insert
866 * it unless such an entry is already in the cache.
867 *
868 * Returns 0, or a negative error number on failure.
869 */
870static int
871ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)
872{
873 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
874 int error;
875
876 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr,
877 true);
878 if (error) {
879 if (error == -EBUSY) {
880 ea_bdebug(bh, "already in cache");
881 error = 0;
882 }
883 } else
884 ea_bdebug(bh, "inserting [%x]", (int)hash);
885 return error;
886}
887
888/*
889 * ext2_xattr_cmp()
890 *
891 * Compare two extended attribute blocks for equality.
892 *
893 * Returns 0 if the blocks are equal, 1 if they differ, and
894 * a negative error number on errors.
895 */
896static int
897ext2_xattr_cmp(struct ext2_xattr_header *header1,
898 struct ext2_xattr_header *header2)
899{
900 struct ext2_xattr_entry *entry1, *entry2;
901
902 entry1 = ENTRY(header1+1);
903 entry2 = ENTRY(header2+1);
904 while (!IS_LAST_ENTRY(entry1)) {
905 if (IS_LAST_ENTRY(entry2))
906 return 1;
907 if (entry1->e_hash != entry2->e_hash ||
908 entry1->e_name_index != entry2->e_name_index ||
909 entry1->e_name_len != entry2->e_name_len ||
910 entry1->e_value_size != entry2->e_value_size ||
911 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
912 return 1;
913 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
914 return -EIO;
915 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
916 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
917 le32_to_cpu(entry1->e_value_size)))
918 return 1;
919
920 entry1 = EXT2_XATTR_NEXT(entry1);
921 entry2 = EXT2_XATTR_NEXT(entry2);
922 }
923 if (!IS_LAST_ENTRY(entry2))
924 return 1;
925 return 0;
926}
927
928/*
929 * ext2_xattr_cache_find()
930 *
931 * Find an identical extended attribute block.
932 *
933 * Returns a locked buffer head to the block found, or NULL if such
934 * a block was not found or an error occurred.
935 */
936static struct buffer_head *
937ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
938{
939 __u32 hash = le32_to_cpu(header->h_hash);
940 struct mb_cache_entry *ce;
941 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
942
943 if (!header->h_hash)
944 return NULL; /* never share */
945 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
946again:
947 ce = mb_cache_entry_find_first(ea_block_cache, hash);
948 while (ce) {
949 struct buffer_head *bh;
950
951 bh = sb_bread(inode->i_sb, ce->e_value);
952 if (!bh) {
953 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
954 "inode %ld: block %ld read error",
955 inode->i_ino, (unsigned long) ce->e_value);
956 } else {
957 lock_buffer(bh);
958 /*
959 * We have to be careful about races with freeing or
960 * rehashing of xattr block. Once we hold buffer lock
961 * xattr block's state is stable so we can check
962 * whether the block got freed / rehashed or not.
963 * Since we unhash mbcache entry under buffer lock when
964 * freeing / rehashing xattr block, checking whether
965 * entry is still hashed is reliable.
966 */
967 if (hlist_bl_unhashed(&ce->e_hash_list)) {
968 mb_cache_entry_put(ea_block_cache, ce);
969 unlock_buffer(bh);
970 brelse(bh);
971 goto again;
972 } else if (le32_to_cpu(HDR(bh)->h_refcount) >
973 EXT2_XATTR_REFCOUNT_MAX) {
974 ea_idebug(inode, "block %ld refcount %d>%d",
975 (unsigned long) ce->e_value,
976 le32_to_cpu(HDR(bh)->h_refcount),
977 EXT2_XATTR_REFCOUNT_MAX);
978 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
979 ea_bdebug(bh, "b_count=%d",
980 atomic_read(&(bh->b_count)));
981 mb_cache_entry_touch(ea_block_cache, ce);
982 mb_cache_entry_put(ea_block_cache, ce);
983 return bh;
984 }
985 unlock_buffer(bh);
986 brelse(bh);
987 }
988 ce = mb_cache_entry_find_next(ea_block_cache, ce);
989 }
990 return NULL;
991}
992
993#define NAME_HASH_SHIFT 5
994#define VALUE_HASH_SHIFT 16
995
996/*
997 * ext2_xattr_hash_entry()
998 *
999 * Compute the hash of an extended attribute.
1000 */
1001static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
1002 struct ext2_xattr_entry *entry)
1003{
1004 __u32 hash = 0;
1005 char *name = entry->e_name;
1006 int n;
1007
1008 for (n=0; n < entry->e_name_len; n++) {
1009 hash = (hash << NAME_HASH_SHIFT) ^
1010 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1011 *name++;
1012 }
1013
1014 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1015 __le32 *value = (__le32 *)((char *)header +
1016 le16_to_cpu(entry->e_value_offs));
1017 for (n = (le32_to_cpu(entry->e_value_size) +
1018 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
1019 hash = (hash << VALUE_HASH_SHIFT) ^
1020 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1021 le32_to_cpu(*value++);
1022 }
1023 }
1024 entry->e_hash = cpu_to_le32(hash);
1025}
1026
1027#undef NAME_HASH_SHIFT
1028#undef VALUE_HASH_SHIFT
1029
1030#define BLOCK_HASH_SHIFT 16
1031
1032/*
1033 * ext2_xattr_rehash()
1034 *
1035 * Re-compute the extended attribute hash value after an entry has changed.
1036 */
1037static void ext2_xattr_rehash(struct ext2_xattr_header *header,
1038 struct ext2_xattr_entry *entry)
1039{
1040 struct ext2_xattr_entry *here;
1041 __u32 hash = 0;
1042
1043 ext2_xattr_hash_entry(header, entry);
1044 here = ENTRY(header+1);
1045 while (!IS_LAST_ENTRY(here)) {
1046 if (!here->e_hash) {
1047 /* Block is not shared if an entry's hash value == 0 */
1048 hash = 0;
1049 break;
1050 }
1051 hash = (hash << BLOCK_HASH_SHIFT) ^
1052 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1053 le32_to_cpu(here->e_hash);
1054 here = EXT2_XATTR_NEXT(here);
1055 }
1056 header->h_hash = cpu_to_le32(hash);
1057}
1058
1059#undef BLOCK_HASH_SHIFT
1060
1061#define HASH_BUCKET_BITS 10
1062
1063struct mb_cache *ext2_xattr_create_cache(void)
1064{
1065 return mb_cache_create(HASH_BUCKET_BITS);
1066}
1067
1068void ext2_xattr_destroy_cache(struct mb_cache *cache)
1069{
1070 if (cache)
1071 mb_cache_destroy(cache);
1072}