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 alligned 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/module.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 "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
92 static int ext2_xattr_set2(struct inode *, struct buffer_head *,
93 struct ext2_xattr_header *);
94
95 static int ext2_xattr_cache_insert(struct buffer_head *);
96 static struct buffer_head *ext2_xattr_cache_find(struct inode *,
97 struct ext2_xattr_header *);
98 static void ext2_xattr_rehash(struct ext2_xattr_header *,
99 struct ext2_xattr_entry *);
100
101 static struct mb_cache *ext2_xattr_cache;
102
103 static struct xattr_handler *ext2_xattr_handler_map[] = {
104 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
105 #ifdef CONFIG_EXT2_FS_POSIX_ACL
106 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler,
107 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler,
108 #endif
109 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
110 #ifdef CONFIG_EXT2_FS_SECURITY
111 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
112 #endif
113 };
114
115 struct xattr_handler *ext2_xattr_handlers[] = {
116 &ext2_xattr_user_handler,
117 &ext2_xattr_trusted_handler,
118 #ifdef CONFIG_EXT2_FS_POSIX_ACL
119 &ext2_xattr_acl_access_handler,
120 &ext2_xattr_acl_default_handler,
121 #endif
122 #ifdef CONFIG_EXT2_FS_SECURITY
123 &ext2_xattr_security_handler,
124 #endif
125 NULL
126 };
127
128 static inline struct xattr_handler *
129 ext2_xattr_handler(int name_index)
130 {
131 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 */
148 int
149 ext2_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 down_read(&EXT2_I(inode)->xattr_sem);
164 error = -ENODATA;
165 if (!EXT2_I(inode)->i_file_acl)
166 goto cleanup;
167 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
168 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
169 error = -EIO;
170 if (!bh)
171 goto cleanup;
172 ea_bdebug(bh, "b_count=%d, refcount=%d",
173 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
174 end = bh->b_data + bh->b_size;
175 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
176 HDR(bh)->h_blocks != cpu_to_le32(1)) {
177 bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
178 "inode %ld: bad block %d", inode->i_ino,
179 EXT2_I(inode)->i_file_acl);
180 error = -EIO;
181 goto cleanup;
182 }
183 /* find named attribute */
184 name_len = strlen(name);
185
186 error = -ERANGE;
187 if (name_len > 255)
188 goto cleanup;
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 /* Check the remaining name entries */
202 while (!IS_LAST_ENTRY(entry)) {
203 struct ext2_xattr_entry *next =
204 EXT2_XATTR_NEXT(entry);
205 if ((char *)next >= end)
206 goto bad_block;
207 entry = next;
208 }
209 if (ext2_xattr_cache_insert(bh))
210 ea_idebug(inode, "cache insert failed");
211 error = -ENODATA;
212 goto cleanup;
213 found:
214 /* check the buffer size */
215 if (entry->e_value_block != 0)
216 goto bad_block;
217 size = le32_to_cpu(entry->e_value_size);
218 if (size > inode->i_sb->s_blocksize ||
219 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
220 goto bad_block;
221
222 if (ext2_xattr_cache_insert(bh))
223 ea_idebug(inode, "cache insert failed");
224 if (buffer) {
225 error = -ERANGE;
226 if (size > buffer_size)
227 goto cleanup;
228 /* return value of attribute */
229 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
230 size);
231 }
232 error = size;
233
234 cleanup:
235 brelse(bh);
236 up_read(&EXT2_I(inode)->xattr_sem);
237
238 return error;
239 }
240
241 /*
242 * ext2_xattr_list()
243 *
244 * Copy a list of attribute names into the buffer
245 * provided, or compute the buffer size required.
246 * Buffer is NULL to compute the size of the buffer required.
247 *
248 * Returns a negative error number on failure, or the number of bytes
249 * used / required on success.
250 */
251 static int
252 ext2_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
253 {
254 struct buffer_head *bh = NULL;
255 struct ext2_xattr_entry *entry;
256 char *end;
257 size_t rest = buffer_size;
258 int error;
259
260 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
261 buffer, (long)buffer_size);
262
263 down_read(&EXT2_I(inode)->xattr_sem);
264 error = 0;
265 if (!EXT2_I(inode)->i_file_acl)
266 goto cleanup;
267 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
268 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
269 error = -EIO;
270 if (!bh)
271 goto cleanup;
272 ea_bdebug(bh, "b_count=%d, refcount=%d",
273 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
274 end = bh->b_data + bh->b_size;
275 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
276 HDR(bh)->h_blocks != cpu_to_le32(1)) {
277 bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
278 "inode %ld: bad block %d", inode->i_ino,
279 EXT2_I(inode)->i_file_acl);
280 error = -EIO;
281 goto cleanup;
282 }
283
284 /* check the on-disk data structure */
285 entry = FIRST_ENTRY(bh);
286 while (!IS_LAST_ENTRY(entry)) {
287 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
288
289 if ((char *)next >= end)
290 goto bad_block;
291 entry = next;
292 }
293 if (ext2_xattr_cache_insert(bh))
294 ea_idebug(inode, "cache insert failed");
295
296 /* list the attribute names */
297 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
298 entry = EXT2_XATTR_NEXT(entry)) {
299 struct xattr_handler *handler =
300 ext2_xattr_handler(entry->e_name_index);
301
302 if (handler) {
303 size_t size = handler->list(inode, buffer, rest,
304 entry->e_name,
305 entry->e_name_len);
306 if (buffer) {
307 if (size > rest) {
308 error = -ERANGE;
309 goto cleanup;
310 }
311 buffer += size;
312 }
313 rest -= size;
314 }
315 }
316 error = buffer_size - rest; /* total size */
317
318 cleanup:
319 brelse(bh);
320 up_read(&EXT2_I(inode)->xattr_sem);
321
322 return error;
323 }
324
325 /*
326 * Inode operation listxattr()
327 *
328 * dentry->d_inode->i_mutex: don't care
329 */
330 ssize_t
331 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
332 {
333 return ext2_xattr_list(dentry->d_inode, buffer, size);
334 }
335
336 /*
337 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
338 * not set, set it.
339 */
340 static void ext2_xattr_update_super_block(struct super_block *sb)
341 {
342 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
343 return;
344
345 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
346 sb->s_dirt = 1;
347 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
348 }
349
350 /*
351 * ext2_xattr_set()
352 *
353 * Create, replace or remove an extended attribute for this inode. Buffer
354 * is NULL to remove an existing extended attribute, and non-NULL to
355 * either replace an existing extended attribute, or create a new extended
356 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
357 * specify that an extended attribute must exist and must not exist
358 * previous to the call, respectively.
359 *
360 * Returns 0, or a negative error number on failure.
361 */
362 int
363 ext2_xattr_set(struct inode *inode, int name_index, const char *name,
364 const void *value, size_t value_len, int flags)
365 {
366 struct super_block *sb = inode->i_sb;
367 struct buffer_head *bh = NULL;
368 struct ext2_xattr_header *header = NULL;
369 struct ext2_xattr_entry *here, *last;
370 size_t name_len, free, min_offs = sb->s_blocksize;
371 int not_found = 1, error;
372 char *end;
373
374 /*
375 * header -- Points either into bh, or to a temporarily
376 * allocated buffer.
377 * here -- The named entry found, or the place for inserting, within
378 * the block pointed to by header.
379 * last -- Points right after the last named entry within the block
380 * pointed to by header.
381 * min_offs -- The offset of the first value (values are aligned
382 * towards the end of the block).
383 * end -- Points right after the block pointed to by header.
384 */
385
386 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
387 name_index, name, value, (long)value_len);
388
389 if (value == NULL)
390 value_len = 0;
391 if (name == NULL)
392 return -EINVAL;
393 name_len = strlen(name);
394 if (name_len > 255 || value_len > sb->s_blocksize)
395 return -ERANGE;
396 down_write(&EXT2_I(inode)->xattr_sem);
397 if (EXT2_I(inode)->i_file_acl) {
398 /* The inode already has an extended attribute block. */
399 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
400 error = -EIO;
401 if (!bh)
402 goto cleanup;
403 ea_bdebug(bh, "b_count=%d, refcount=%d",
404 atomic_read(&(bh->b_count)),
405 le32_to_cpu(HDR(bh)->h_refcount));
406 header = HDR(bh);
407 end = bh->b_data + bh->b_size;
408 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
409 header->h_blocks != cpu_to_le32(1)) {
410 bad_block: ext2_error(sb, "ext2_xattr_set",
411 "inode %ld: bad block %d", inode->i_ino,
412 EXT2_I(inode)->i_file_acl);
413 error = -EIO;
414 goto cleanup;
415 }
416 /* Find the named attribute. */
417 here = FIRST_ENTRY(bh);
418 while (!IS_LAST_ENTRY(here)) {
419 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
420 if ((char *)next >= end)
421 goto bad_block;
422 if (!here->e_value_block && here->e_value_size) {
423 size_t offs = le16_to_cpu(here->e_value_offs);
424 if (offs < min_offs)
425 min_offs = offs;
426 }
427 not_found = name_index - here->e_name_index;
428 if (!not_found)
429 not_found = name_len - here->e_name_len;
430 if (!not_found)
431 not_found = memcmp(name, here->e_name,name_len);
432 if (not_found <= 0)
433 break;
434 here = next;
435 }
436 last = here;
437 /* We still need to compute min_offs and last. */
438 while (!IS_LAST_ENTRY(last)) {
439 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
440 if ((char *)next >= end)
441 goto bad_block;
442 if (!last->e_value_block && last->e_value_size) {
443 size_t offs = le16_to_cpu(last->e_value_offs);
444 if (offs < min_offs)
445 min_offs = offs;
446 }
447 last = next;
448 }
449
450 /* Check whether we have enough space left. */
451 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
452 } else {
453 /* We will use a new extended attribute block. */
454 free = sb->s_blocksize -
455 sizeof(struct ext2_xattr_header) - sizeof(__u32);
456 here = last = NULL; /* avoid gcc uninitialized warning. */
457 }
458
459 if (not_found) {
460 /* Request to remove a nonexistent attribute? */
461 error = -ENODATA;
462 if (flags & XATTR_REPLACE)
463 goto cleanup;
464 error = 0;
465 if (value == NULL)
466 goto cleanup;
467 } else {
468 /* Request to create an existing attribute? */
469 error = -EEXIST;
470 if (flags & XATTR_CREATE)
471 goto cleanup;
472 if (!here->e_value_block && here->e_value_size) {
473 size_t size = le32_to_cpu(here->e_value_size);
474
475 if (le16_to_cpu(here->e_value_offs) + size >
476 sb->s_blocksize || size > sb->s_blocksize)
477 goto bad_block;
478 free += EXT2_XATTR_SIZE(size);
479 }
480 free += EXT2_XATTR_LEN(name_len);
481 }
482 error = -ENOSPC;
483 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
484 goto cleanup;
485
486 /* Here we know that we can set the new attribute. */
487
488 if (header) {
489 struct mb_cache_entry *ce;
490
491 /* assert(header == HDR(bh)); */
492 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
493 bh->b_blocknr);
494 lock_buffer(bh);
495 if (header->h_refcount == cpu_to_le32(1)) {
496 ea_bdebug(bh, "modifying in-place");
497 if (ce)
498 mb_cache_entry_free(ce);
499 /* keep the buffer locked while modifying it. */
500 } else {
501 int offset;
502
503 if (ce)
504 mb_cache_entry_release(ce);
505 unlock_buffer(bh);
506 ea_bdebug(bh, "cloning");
507 header = kmalloc(bh->b_size, GFP_KERNEL);
508 error = -ENOMEM;
509 if (header == NULL)
510 goto cleanup;
511 memcpy(header, HDR(bh), bh->b_size);
512 header->h_refcount = cpu_to_le32(1);
513
514 offset = (char *)here - bh->b_data;
515 here = ENTRY((char *)header + offset);
516 offset = (char *)last - bh->b_data;
517 last = ENTRY((char *)header + offset);
518 }
519 } else {
520 /* Allocate a buffer where we construct the new block. */
521 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
522 error = -ENOMEM;
523 if (header == NULL)
524 goto cleanup;
525 end = (char *)header + sb->s_blocksize;
526 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
527 header->h_blocks = header->h_refcount = cpu_to_le32(1);
528 last = here = ENTRY(header+1);
529 }
530
531 /* Iff we are modifying the block in-place, bh is locked here. */
532
533 if (not_found) {
534 /* Insert the new name. */
535 size_t size = EXT2_XATTR_LEN(name_len);
536 size_t rest = (char *)last - (char *)here;
537 memmove((char *)here + size, here, rest);
538 memset(here, 0, size);
539 here->e_name_index = name_index;
540 here->e_name_len = name_len;
541 memcpy(here->e_name, name, name_len);
542 } else {
543 if (!here->e_value_block && here->e_value_size) {
544 char *first_val = (char *)header + min_offs;
545 size_t offs = le16_to_cpu(here->e_value_offs);
546 char *val = (char *)header + offs;
547 size_t size = EXT2_XATTR_SIZE(
548 le32_to_cpu(here->e_value_size));
549
550 if (size == EXT2_XATTR_SIZE(value_len)) {
551 /* The old and the new value have the same
552 size. Just replace. */
553 here->e_value_size = cpu_to_le32(value_len);
554 memset(val + size - EXT2_XATTR_PAD, 0,
555 EXT2_XATTR_PAD); /* Clear pad bytes. */
556 memcpy(val, value, value_len);
557 goto skip_replace;
558 }
559
560 /* Remove the old value. */
561 memmove(first_val + size, first_val, val - first_val);
562 memset(first_val, 0, size);
563 here->e_value_offs = 0;
564 min_offs += size;
565
566 /* Adjust all value offsets. */
567 last = ENTRY(header+1);
568 while (!IS_LAST_ENTRY(last)) {
569 size_t o = le16_to_cpu(last->e_value_offs);
570 if (!last->e_value_block && o < offs)
571 last->e_value_offs =
572 cpu_to_le16(o + size);
573 last = EXT2_XATTR_NEXT(last);
574 }
575 }
576 if (value == NULL) {
577 /* Remove the old name. */
578 size_t size = EXT2_XATTR_LEN(name_len);
579 last = ENTRY((char *)last - size);
580 memmove(here, (char*)here + size,
581 (char*)last - (char*)here);
582 memset(last, 0, size);
583 }
584 }
585
586 if (value != NULL) {
587 /* Insert the new value. */
588 here->e_value_size = cpu_to_le32(value_len);
589 if (value_len) {
590 size_t size = EXT2_XATTR_SIZE(value_len);
591 char *val = (char *)header + min_offs - size;
592 here->e_value_offs =
593 cpu_to_le16((char *)val - (char *)header);
594 memset(val + size - EXT2_XATTR_PAD, 0,
595 EXT2_XATTR_PAD); /* Clear the pad bytes. */
596 memcpy(val, value, value_len);
597 }
598 }
599
600 skip_replace:
601 if (IS_LAST_ENTRY(ENTRY(header+1))) {
602 /* This block is now empty. */
603 if (bh && header == HDR(bh))
604 unlock_buffer(bh); /* we were modifying in-place. */
605 error = ext2_xattr_set2(inode, bh, NULL);
606 } else {
607 ext2_xattr_rehash(header, here);
608 if (bh && header == HDR(bh))
609 unlock_buffer(bh); /* we were modifying in-place. */
610 error = ext2_xattr_set2(inode, bh, header);
611 }
612
613 cleanup:
614 brelse(bh);
615 if (!(bh && header == HDR(bh)))
616 kfree(header);
617 up_write(&EXT2_I(inode)->xattr_sem);
618
619 return error;
620 }
621
622 /*
623 * Second half of ext2_xattr_set(): Update the file system.
624 */
625 static int
626 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
627 struct ext2_xattr_header *header)
628 {
629 struct super_block *sb = inode->i_sb;
630 struct buffer_head *new_bh = NULL;
631 int error;
632
633 if (header) {
634 new_bh = ext2_xattr_cache_find(inode, header);
635 if (new_bh) {
636 /* We found an identical block in the cache. */
637 if (new_bh == old_bh) {
638 ea_bdebug(new_bh, "keeping this block");
639 } else {
640 /* The old block is released after updating
641 the inode. */
642 ea_bdebug(new_bh, "reusing block");
643
644 error = -EDQUOT;
645 if (DQUOT_ALLOC_BLOCK(inode, 1)) {
646 unlock_buffer(new_bh);
647 goto cleanup;
648 }
649 HDR(new_bh)->h_refcount = cpu_to_le32(1 +
650 le32_to_cpu(HDR(new_bh)->h_refcount));
651 ea_bdebug(new_bh, "refcount now=%d",
652 le32_to_cpu(HDR(new_bh)->h_refcount));
653 }
654 unlock_buffer(new_bh);
655 } else if (old_bh && header == HDR(old_bh)) {
656 /* Keep this block. No need to lock the block as we
657 don't need to change the reference count. */
658 new_bh = old_bh;
659 get_bh(new_bh);
660 ext2_xattr_cache_insert(new_bh);
661 } else {
662 /* We need to allocate a new block */
663 int goal = le32_to_cpu(EXT2_SB(sb)->s_es->
664 s_first_data_block) +
665 EXT2_I(inode)->i_block_group *
666 EXT2_BLOCKS_PER_GROUP(sb);
667 int block = ext2_new_block(inode, goal, &error);
668 if (error)
669 goto cleanup;
670 ea_idebug(inode, "creating block %d", block);
671
672 new_bh = sb_getblk(sb, block);
673 if (!new_bh) {
674 ext2_free_blocks(inode, block, 1);
675 error = -EIO;
676 goto cleanup;
677 }
678 lock_buffer(new_bh);
679 memcpy(new_bh->b_data, header, new_bh->b_size);
680 set_buffer_uptodate(new_bh);
681 unlock_buffer(new_bh);
682 ext2_xattr_cache_insert(new_bh);
683
684 ext2_xattr_update_super_block(sb);
685 }
686 mark_buffer_dirty(new_bh);
687 if (IS_SYNC(inode)) {
688 sync_dirty_buffer(new_bh);
689 error = -EIO;
690 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
691 goto cleanup;
692 }
693 }
694
695 /* Update the inode. */
696 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
697 inode->i_ctime = CURRENT_TIME_SEC;
698 if (IS_SYNC(inode)) {
699 error = ext2_sync_inode (inode);
700 /* In case sync failed due to ENOSPC the inode was actually
701 * written (only some dirty data were not) so we just proceed
702 * as if nothing happened and cleanup the unused block */
703 if (error && error != -ENOSPC) {
704 if (new_bh && new_bh != old_bh)
705 DQUOT_FREE_BLOCK(inode, 1);
706 goto cleanup;
707 }
708 } else
709 mark_inode_dirty(inode);
710
711 error = 0;
712 if (old_bh && old_bh != new_bh) {
713 struct mb_cache_entry *ce;
714
715 /*
716 * If there was an old block and we are no longer using it,
717 * release the old block.
718 */
719 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
720 old_bh->b_blocknr);
721 lock_buffer(old_bh);
722 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
723 /* Free the old block. */
724 if (ce)
725 mb_cache_entry_free(ce);
726 ea_bdebug(old_bh, "freeing");
727 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
728 /* We let our caller release old_bh, so we
729 * need to duplicate the buffer before. */
730 get_bh(old_bh);
731 bforget(old_bh);
732 } else {
733 /* Decrement the refcount only. */
734 HDR(old_bh)->h_refcount = cpu_to_le32(
735 le32_to_cpu(HDR(old_bh)->h_refcount) - 1);
736 if (ce)
737 mb_cache_entry_release(ce);
738 DQUOT_FREE_BLOCK(inode, 1);
739 mark_buffer_dirty(old_bh);
740 ea_bdebug(old_bh, "refcount now=%d",
741 le32_to_cpu(HDR(old_bh)->h_refcount));
742 }
743 unlock_buffer(old_bh);
744 }
745
746 cleanup:
747 brelse(new_bh);
748
749 return error;
750 }
751
752 /*
753 * ext2_xattr_delete_inode()
754 *
755 * Free extended attribute resources associated with this inode. This
756 * is called immediately before an inode is freed.
757 */
758 void
759 ext2_xattr_delete_inode(struct inode *inode)
760 {
761 struct buffer_head *bh = NULL;
762 struct mb_cache_entry *ce;
763
764 down_write(&EXT2_I(inode)->xattr_sem);
765 if (!EXT2_I(inode)->i_file_acl)
766 goto cleanup;
767 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
768 if (!bh) {
769 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
770 "inode %ld: block %d read error", inode->i_ino,
771 EXT2_I(inode)->i_file_acl);
772 goto cleanup;
773 }
774 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
775 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
776 HDR(bh)->h_blocks != cpu_to_le32(1)) {
777 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
778 "inode %ld: bad block %d", inode->i_ino,
779 EXT2_I(inode)->i_file_acl);
780 goto cleanup;
781 }
782 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
783 lock_buffer(bh);
784 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
785 if (ce)
786 mb_cache_entry_free(ce);
787 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
788 get_bh(bh);
789 bforget(bh);
790 unlock_buffer(bh);
791 } else {
792 HDR(bh)->h_refcount = cpu_to_le32(
793 le32_to_cpu(HDR(bh)->h_refcount) - 1);
794 if (ce)
795 mb_cache_entry_release(ce);
796 ea_bdebug(bh, "refcount now=%d",
797 le32_to_cpu(HDR(bh)->h_refcount));
798 unlock_buffer(bh);
799 mark_buffer_dirty(bh);
800 if (IS_SYNC(inode))
801 sync_dirty_buffer(bh);
802 DQUOT_FREE_BLOCK(inode, 1);
803 }
804 EXT2_I(inode)->i_file_acl = 0;
805
806 cleanup:
807 brelse(bh);
808 up_write(&EXT2_I(inode)->xattr_sem);
809 }
810
811 /*
812 * ext2_xattr_put_super()
813 *
814 * This is called when a file system is unmounted.
815 */
816 void
817 ext2_xattr_put_super(struct super_block *sb)
818 {
819 mb_cache_shrink(sb->s_bdev);
820 }
821
822
823 /*
824 * ext2_xattr_cache_insert()
825 *
826 * Create a new entry in the extended attribute cache, and insert
827 * it unless such an entry is already in the cache.
828 *
829 * Returns 0, or a negative error number on failure.
830 */
831 static int
832 ext2_xattr_cache_insert(struct buffer_head *bh)
833 {
834 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
835 struct mb_cache_entry *ce;
836 int error;
837
838 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
839 if (!ce)
840 return -ENOMEM;
841 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
842 if (error) {
843 mb_cache_entry_free(ce);
844 if (error == -EBUSY) {
845 ea_bdebug(bh, "already in cache (%d cache entries)",
846 atomic_read(&ext2_xattr_cache->c_entry_count));
847 error = 0;
848 }
849 } else {
850 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
851 atomic_read(&ext2_xattr_cache->c_entry_count));
852 mb_cache_entry_release(ce);
853 }
854 return error;
855 }
856
857 /*
858 * ext2_xattr_cmp()
859 *
860 * Compare two extended attribute blocks for equality.
861 *
862 * Returns 0 if the blocks are equal, 1 if they differ, and
863 * a negative error number on errors.
864 */
865 static int
866 ext2_xattr_cmp(struct ext2_xattr_header *header1,
867 struct ext2_xattr_header *header2)
868 {
869 struct ext2_xattr_entry *entry1, *entry2;
870
871 entry1 = ENTRY(header1+1);
872 entry2 = ENTRY(header2+1);
873 while (!IS_LAST_ENTRY(entry1)) {
874 if (IS_LAST_ENTRY(entry2))
875 return 1;
876 if (entry1->e_hash != entry2->e_hash ||
877 entry1->e_name_index != entry2->e_name_index ||
878 entry1->e_name_len != entry2->e_name_len ||
879 entry1->e_value_size != entry2->e_value_size ||
880 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
881 return 1;
882 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
883 return -EIO;
884 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
885 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
886 le32_to_cpu(entry1->e_value_size)))
887 return 1;
888
889 entry1 = EXT2_XATTR_NEXT(entry1);
890 entry2 = EXT2_XATTR_NEXT(entry2);
891 }
892 if (!IS_LAST_ENTRY(entry2))
893 return 1;
894 return 0;
895 }
896
897 /*
898 * ext2_xattr_cache_find()
899 *
900 * Find an identical extended attribute block.
901 *
902 * Returns a locked buffer head to the block found, or NULL if such
903 * a block was not found or an error occurred.
904 */
905 static struct buffer_head *
906 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
907 {
908 __u32 hash = le32_to_cpu(header->h_hash);
909 struct mb_cache_entry *ce;
910
911 if (!header->h_hash)
912 return NULL; /* never share */
913 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
914 again:
915 ce = mb_cache_entry_find_first(ext2_xattr_cache, 0,
916 inode->i_sb->s_bdev, hash);
917 while (ce) {
918 struct buffer_head *bh;
919
920 if (IS_ERR(ce)) {
921 if (PTR_ERR(ce) == -EAGAIN)
922 goto again;
923 break;
924 }
925
926 bh = sb_bread(inode->i_sb, ce->e_block);
927 if (!bh) {
928 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
929 "inode %ld: block %ld read error",
930 inode->i_ino, (unsigned long) ce->e_block);
931 } else {
932 lock_buffer(bh);
933 if (le32_to_cpu(HDR(bh)->h_refcount) >
934 EXT2_XATTR_REFCOUNT_MAX) {
935 ea_idebug(inode, "block %ld refcount %d>%d",
936 (unsigned long) ce->e_block,
937 le32_to_cpu(HDR(bh)->h_refcount),
938 EXT2_XATTR_REFCOUNT_MAX);
939 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
940 ea_bdebug(bh, "b_count=%d",
941 atomic_read(&(bh->b_count)));
942 mb_cache_entry_release(ce);
943 return bh;
944 }
945 unlock_buffer(bh);
946 brelse(bh);
947 }
948 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
949 }
950 return NULL;
951 }
952
953 #define NAME_HASH_SHIFT 5
954 #define VALUE_HASH_SHIFT 16
955
956 /*
957 * ext2_xattr_hash_entry()
958 *
959 * Compute the hash of an extended attribute.
960 */
961 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
962 struct ext2_xattr_entry *entry)
963 {
964 __u32 hash = 0;
965 char *name = entry->e_name;
966 int n;
967
968 for (n=0; n < entry->e_name_len; n++) {
969 hash = (hash << NAME_HASH_SHIFT) ^
970 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
971 *name++;
972 }
973
974 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
975 __le32 *value = (__le32 *)((char *)header +
976 le16_to_cpu(entry->e_value_offs));
977 for (n = (le32_to_cpu(entry->e_value_size) +
978 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
979 hash = (hash << VALUE_HASH_SHIFT) ^
980 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
981 le32_to_cpu(*value++);
982 }
983 }
984 entry->e_hash = cpu_to_le32(hash);
985 }
986
987 #undef NAME_HASH_SHIFT
988 #undef VALUE_HASH_SHIFT
989
990 #define BLOCK_HASH_SHIFT 16
991
992 /*
993 * ext2_xattr_rehash()
994 *
995 * Re-compute the extended attribute hash value after an entry has changed.
996 */
997 static void ext2_xattr_rehash(struct ext2_xattr_header *header,
998 struct ext2_xattr_entry *entry)
999 {
1000 struct ext2_xattr_entry *here;
1001 __u32 hash = 0;
1002
1003 ext2_xattr_hash_entry(header, entry);
1004 here = ENTRY(header+1);
1005 while (!IS_LAST_ENTRY(here)) {
1006 if (!here->e_hash) {
1007 /* Block is not shared if an entry's hash value == 0 */
1008 hash = 0;
1009 break;
1010 }
1011 hash = (hash << BLOCK_HASH_SHIFT) ^
1012 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1013 le32_to_cpu(here->e_hash);
1014 here = EXT2_XATTR_NEXT(here);
1015 }
1016 header->h_hash = cpu_to_le32(hash);
1017 }
1018
1019 #undef BLOCK_HASH_SHIFT
1020
1021 int __init
1022 init_ext2_xattr(void)
1023 {
1024 ext2_xattr_cache = mb_cache_create("ext2_xattr", NULL,
1025 sizeof(struct mb_cache_entry) +
1026 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1027 if (!ext2_xattr_cache)
1028 return -ENOMEM;
1029 return 0;
1030 }
1031
1032 void
1033 exit_ext2_xattr(void)
1034 {
1035 mb_cache_destroy(ext2_xattr_cache);
1036 }
1037
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