Merge branch 'setns'
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / ext2 / xattr.c
blob529970617a21c5c45cd1cffa1b39c14f318d72aa
1 /*
2 * linux/fs/ext2/xattr.c
4 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>
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.
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.
23 * Extended attribute block layout:
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 * +------------------+
37 * The block header is followed by multiple entry descriptors. These entry
38 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD
39 * byte boundaries. The entry descriptors are sorted by attribute name,
40 * so that two extended attribute blocks can be compared efficiently.
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.
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.
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 <linux/security.h>
64 #include "ext2.h"
65 #include "xattr.h"
66 #include "acl.h"
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)
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 char b[BDEVNAME_SIZE]; \
82 printk(KERN_DEBUG "block %s:%lu: ", \
83 bdevname(bh->b_bdev, b), \
84 (unsigned long) bh->b_blocknr); \
85 printk(f); \
86 printk("\n"); \
87 } while (0)
88 #else
89 # define ea_idebug(f...)
90 # define ea_bdebug(f...)
91 #endif
93 static int ext2_xattr_set2(struct inode *, struct buffer_head *,
94 struct ext2_xattr_header *);
96 static int ext2_xattr_cache_insert(struct buffer_head *);
97 static struct buffer_head *ext2_xattr_cache_find(struct inode *,
98 struct ext2_xattr_header *);
99 static void ext2_xattr_rehash(struct ext2_xattr_header *,
100 struct ext2_xattr_entry *);
102 static struct mb_cache *ext2_xattr_cache;
104 static const struct xattr_handler *ext2_xattr_handler_map[] = {
105 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,
106 #ifdef CONFIG_EXT2_FS_POSIX_ACL
107 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler,
108 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler,
109 #endif
110 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
111 #ifdef CONFIG_EXT2_FS_SECURITY
112 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
113 #endif
116 const struct xattr_handler *ext2_xattr_handlers[] = {
117 &ext2_xattr_user_handler,
118 &ext2_xattr_trusted_handler,
119 #ifdef CONFIG_EXT2_FS_POSIX_ACL
120 &ext2_xattr_acl_access_handler,
121 &ext2_xattr_acl_default_handler,
122 #endif
123 #ifdef CONFIG_EXT2_FS_SECURITY
124 &ext2_xattr_security_handler,
125 #endif
126 NULL
129 static inline const struct xattr_handler *
130 ext2_xattr_handler(int name_index)
132 const struct xattr_handler *handler = NULL;
134 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))
135 handler = ext2_xattr_handler_map[name_index];
136 return handler;
140 * ext2_xattr_get()
142 * Copy an extended attribute into the buffer
143 * provided, or compute the buffer size required.
144 * Buffer is NULL to compute the size of the buffer required.
146 * Returns a negative error number on failure, or the number of bytes
147 * used / required on success.
150 ext2_xattr_get(struct inode *inode, int name_index, const char *name,
151 void *buffer, size_t buffer_size)
153 struct buffer_head *bh = NULL;
154 struct ext2_xattr_entry *entry;
155 size_t name_len, size;
156 char *end;
157 int error;
159 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
160 name_index, name, buffer, (long)buffer_size);
162 if (name == NULL)
163 return -EINVAL;
164 down_read(&EXT2_I(inode)->xattr_sem);
165 error = -ENODATA;
166 if (!EXT2_I(inode)->i_file_acl)
167 goto cleanup;
168 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
169 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
170 error = -EIO;
171 if (!bh)
172 goto cleanup;
173 ea_bdebug(bh, "b_count=%d, refcount=%d",
174 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
175 end = bh->b_data + bh->b_size;
176 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
177 HDR(bh)->h_blocks != cpu_to_le32(1)) {
178 bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
179 "inode %ld: bad block %d", inode->i_ino,
180 EXT2_I(inode)->i_file_acl);
181 error = -EIO;
182 goto cleanup;
184 /* find named attribute */
185 name_len = strlen(name);
187 error = -ERANGE;
188 if (name_len > 255)
189 goto cleanup;
190 entry = FIRST_ENTRY(bh);
191 while (!IS_LAST_ENTRY(entry)) {
192 struct ext2_xattr_entry *next =
193 EXT2_XATTR_NEXT(entry);
194 if ((char *)next >= end)
195 goto bad_block;
196 if (name_index == entry->e_name_index &&
197 name_len == entry->e_name_len &&
198 memcmp(name, entry->e_name, name_len) == 0)
199 goto found;
200 entry = next;
202 if (ext2_xattr_cache_insert(bh))
203 ea_idebug(inode, "cache insert failed");
204 error = -ENODATA;
205 goto cleanup;
206 found:
207 /* check the buffer size */
208 if (entry->e_value_block != 0)
209 goto bad_block;
210 size = le32_to_cpu(entry->e_value_size);
211 if (size > inode->i_sb->s_blocksize ||
212 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
213 goto bad_block;
215 if (ext2_xattr_cache_insert(bh))
216 ea_idebug(inode, "cache insert failed");
217 if (buffer) {
218 error = -ERANGE;
219 if (size > buffer_size)
220 goto cleanup;
221 /* return value of attribute */
222 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
223 size);
225 error = size;
227 cleanup:
228 brelse(bh);
229 up_read(&EXT2_I(inode)->xattr_sem);
231 return error;
235 * ext2_xattr_list()
237 * Copy a list of attribute names into the buffer
238 * provided, or compute the buffer size required.
239 * Buffer is NULL to compute the size of the buffer required.
241 * Returns a negative error number on failure, or the number of bytes
242 * used / required on success.
244 static int
245 ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
247 struct inode *inode = dentry->d_inode;
248 struct buffer_head *bh = NULL;
249 struct ext2_xattr_entry *entry;
250 char *end;
251 size_t rest = buffer_size;
252 int error;
254 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
255 buffer, (long)buffer_size);
257 down_read(&EXT2_I(inode)->xattr_sem);
258 error = 0;
259 if (!EXT2_I(inode)->i_file_acl)
260 goto cleanup;
261 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
262 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
263 error = -EIO;
264 if (!bh)
265 goto cleanup;
266 ea_bdebug(bh, "b_count=%d, refcount=%d",
267 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
268 end = bh->b_data + bh->b_size;
269 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
270 HDR(bh)->h_blocks != cpu_to_le32(1)) {
271 bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
272 "inode %ld: bad block %d", inode->i_ino,
273 EXT2_I(inode)->i_file_acl);
274 error = -EIO;
275 goto cleanup;
278 /* check the on-disk data structure */
279 entry = FIRST_ENTRY(bh);
280 while (!IS_LAST_ENTRY(entry)) {
281 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
283 if ((char *)next >= end)
284 goto bad_block;
285 entry = next;
287 if (ext2_xattr_cache_insert(bh))
288 ea_idebug(inode, "cache insert failed");
290 /* list the attribute names */
291 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
292 entry = EXT2_XATTR_NEXT(entry)) {
293 const struct xattr_handler *handler =
294 ext2_xattr_handler(entry->e_name_index);
296 if (handler) {
297 size_t size = handler->list(dentry, buffer, rest,
298 entry->e_name,
299 entry->e_name_len,
300 handler->flags);
301 if (buffer) {
302 if (size > rest) {
303 error = -ERANGE;
304 goto cleanup;
306 buffer += size;
308 rest -= size;
311 error = buffer_size - rest; /* total size */
313 cleanup:
314 brelse(bh);
315 up_read(&EXT2_I(inode)->xattr_sem);
317 return error;
321 * Inode operation listxattr()
323 * dentry->d_inode->i_mutex: don't care
325 ssize_t
326 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
328 return ext2_xattr_list(dentry, buffer, size);
332 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
333 * not set, set it.
335 static void ext2_xattr_update_super_block(struct super_block *sb)
337 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
338 return;
340 spin_lock(&EXT2_SB(sb)->s_lock);
341 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
342 spin_unlock(&EXT2_SB(sb)->s_lock);
343 sb->s_dirt = 1;
344 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
348 * ext2_xattr_set()
350 * Create, replace or remove an extended attribute for this inode. Value
351 * is NULL to remove an existing extended attribute, and non-NULL to
352 * either replace an existing extended attribute, or create a new extended
353 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
354 * specify that an extended attribute must exist and must not exist
355 * previous to the call, respectively.
357 * Returns 0, or a negative error number on failure.
360 ext2_xattr_set(struct inode *inode, int name_index, const char *name,
361 const void *value, size_t value_len, int flags)
363 struct super_block *sb = inode->i_sb;
364 struct buffer_head *bh = NULL;
365 struct ext2_xattr_header *header = NULL;
366 struct ext2_xattr_entry *here, *last;
367 size_t name_len, free, min_offs = sb->s_blocksize;
368 int not_found = 1, error;
369 char *end;
372 * header -- Points either into bh, or to a temporarily
373 * allocated buffer.
374 * here -- The named entry found, or the place for inserting, within
375 * the block pointed to by header.
376 * last -- Points right after the last named entry within the block
377 * pointed to by header.
378 * min_offs -- The offset of the first value (values are aligned
379 * towards the end of the block).
380 * end -- Points right after the block pointed to by header.
383 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
384 name_index, name, value, (long)value_len);
386 if (value == NULL)
387 value_len = 0;
388 if (name == NULL)
389 return -EINVAL;
390 name_len = strlen(name);
391 if (name_len > 255 || value_len > sb->s_blocksize)
392 return -ERANGE;
393 down_write(&EXT2_I(inode)->xattr_sem);
394 if (EXT2_I(inode)->i_file_acl) {
395 /* The inode already has an extended attribute block. */
396 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
397 error = -EIO;
398 if (!bh)
399 goto cleanup;
400 ea_bdebug(bh, "b_count=%d, refcount=%d",
401 atomic_read(&(bh->b_count)),
402 le32_to_cpu(HDR(bh)->h_refcount));
403 header = HDR(bh);
404 end = bh->b_data + bh->b_size;
405 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
406 header->h_blocks != cpu_to_le32(1)) {
407 bad_block: ext2_error(sb, "ext2_xattr_set",
408 "inode %ld: bad block %d", inode->i_ino,
409 EXT2_I(inode)->i_file_acl);
410 error = -EIO;
411 goto cleanup;
413 /* Find the named attribute. */
414 here = FIRST_ENTRY(bh);
415 while (!IS_LAST_ENTRY(here)) {
416 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
417 if ((char *)next >= end)
418 goto bad_block;
419 if (!here->e_value_block && here->e_value_size) {
420 size_t offs = le16_to_cpu(here->e_value_offs);
421 if (offs < min_offs)
422 min_offs = offs;
424 not_found = name_index - here->e_name_index;
425 if (!not_found)
426 not_found = name_len - here->e_name_len;
427 if (!not_found)
428 not_found = memcmp(name, here->e_name,name_len);
429 if (not_found <= 0)
430 break;
431 here = next;
433 last = here;
434 /* We still need to compute min_offs and last. */
435 while (!IS_LAST_ENTRY(last)) {
436 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
437 if ((char *)next >= end)
438 goto bad_block;
439 if (!last->e_value_block && last->e_value_size) {
440 size_t offs = le16_to_cpu(last->e_value_offs);
441 if (offs < min_offs)
442 min_offs = offs;
444 last = next;
447 /* Check whether we have enough space left. */
448 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
449 } else {
450 /* We will use a new extended attribute block. */
451 free = sb->s_blocksize -
452 sizeof(struct ext2_xattr_header) - sizeof(__u32);
453 here = last = NULL; /* avoid gcc uninitialized warning. */
456 if (not_found) {
457 /* Request to remove a nonexistent attribute? */
458 error = -ENODATA;
459 if (flags & XATTR_REPLACE)
460 goto cleanup;
461 error = 0;
462 if (value == NULL)
463 goto cleanup;
464 } else {
465 /* Request to create an existing attribute? */
466 error = -EEXIST;
467 if (flags & XATTR_CREATE)
468 goto cleanup;
469 if (!here->e_value_block && here->e_value_size) {
470 size_t size = le32_to_cpu(here->e_value_size);
472 if (le16_to_cpu(here->e_value_offs) + size >
473 sb->s_blocksize || size > sb->s_blocksize)
474 goto bad_block;
475 free += EXT2_XATTR_SIZE(size);
477 free += EXT2_XATTR_LEN(name_len);
479 error = -ENOSPC;
480 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
481 goto cleanup;
483 /* Here we know that we can set the new attribute. */
485 if (header) {
486 struct mb_cache_entry *ce;
488 /* assert(header == HDR(bh)); */
489 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
490 bh->b_blocknr);
491 lock_buffer(bh);
492 if (header->h_refcount == cpu_to_le32(1)) {
493 ea_bdebug(bh, "modifying in-place");
494 if (ce)
495 mb_cache_entry_free(ce);
496 /* keep the buffer locked while modifying it. */
497 } else {
498 int offset;
500 if (ce)
501 mb_cache_entry_release(ce);
502 unlock_buffer(bh);
503 ea_bdebug(bh, "cloning");
504 header = kmalloc(bh->b_size, GFP_KERNEL);
505 error = -ENOMEM;
506 if (header == NULL)
507 goto cleanup;
508 memcpy(header, HDR(bh), bh->b_size);
509 header->h_refcount = cpu_to_le32(1);
511 offset = (char *)here - bh->b_data;
512 here = ENTRY((char *)header + offset);
513 offset = (char *)last - bh->b_data;
514 last = ENTRY((char *)header + offset);
516 } else {
517 /* Allocate a buffer where we construct the new block. */
518 header = kzalloc(sb->s_blocksize, GFP_KERNEL);
519 error = -ENOMEM;
520 if (header == NULL)
521 goto cleanup;
522 end = (char *)header + sb->s_blocksize;
523 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
524 header->h_blocks = header->h_refcount = cpu_to_le32(1);
525 last = here = ENTRY(header+1);
528 /* Iff we are modifying the block in-place, bh is locked here. */
530 if (not_found) {
531 /* Insert the new name. */
532 size_t size = EXT2_XATTR_LEN(name_len);
533 size_t rest = (char *)last - (char *)here;
534 memmove((char *)here + size, here, rest);
535 memset(here, 0, size);
536 here->e_name_index = name_index;
537 here->e_name_len = name_len;
538 memcpy(here->e_name, name, name_len);
539 } else {
540 if (!here->e_value_block && here->e_value_size) {
541 char *first_val = (char *)header + min_offs;
542 size_t offs = le16_to_cpu(here->e_value_offs);
543 char *val = (char *)header + offs;
544 size_t size = EXT2_XATTR_SIZE(
545 le32_to_cpu(here->e_value_size));
547 if (size == EXT2_XATTR_SIZE(value_len)) {
548 /* The old and the new value have the same
549 size. Just replace. */
550 here->e_value_size = cpu_to_le32(value_len);
551 memset(val + size - EXT2_XATTR_PAD, 0,
552 EXT2_XATTR_PAD); /* Clear pad bytes. */
553 memcpy(val, value, value_len);
554 goto skip_replace;
557 /* Remove the old value. */
558 memmove(first_val + size, first_val, val - first_val);
559 memset(first_val, 0, size);
560 here->e_value_offs = 0;
561 min_offs += size;
563 /* Adjust all value offsets. */
564 last = ENTRY(header+1);
565 while (!IS_LAST_ENTRY(last)) {
566 size_t o = le16_to_cpu(last->e_value_offs);
567 if (!last->e_value_block && o < offs)
568 last->e_value_offs =
569 cpu_to_le16(o + size);
570 last = EXT2_XATTR_NEXT(last);
573 if (value == NULL) {
574 /* Remove the old name. */
575 size_t size = EXT2_XATTR_LEN(name_len);
576 last = ENTRY((char *)last - size);
577 memmove(here, (char*)here + size,
578 (char*)last - (char*)here);
579 memset(last, 0, size);
583 if (value != NULL) {
584 /* Insert the new value. */
585 here->e_value_size = cpu_to_le32(value_len);
586 if (value_len) {
587 size_t size = EXT2_XATTR_SIZE(value_len);
588 char *val = (char *)header + min_offs - size;
589 here->e_value_offs =
590 cpu_to_le16((char *)val - (char *)header);
591 memset(val + size - EXT2_XATTR_PAD, 0,
592 EXT2_XATTR_PAD); /* Clear the pad bytes. */
593 memcpy(val, value, value_len);
597 skip_replace:
598 if (IS_LAST_ENTRY(ENTRY(header+1))) {
599 /* This block is now empty. */
600 if (bh && header == HDR(bh))
601 unlock_buffer(bh); /* we were modifying in-place. */
602 error = ext2_xattr_set2(inode, bh, NULL);
603 } else {
604 ext2_xattr_rehash(header, here);
605 if (bh && header == HDR(bh))
606 unlock_buffer(bh); /* we were modifying in-place. */
607 error = ext2_xattr_set2(inode, bh, header);
610 cleanup:
611 brelse(bh);
612 if (!(bh && header == HDR(bh)))
613 kfree(header);
614 up_write(&EXT2_I(inode)->xattr_sem);
616 return error;
620 * Second half of ext2_xattr_set(): Update the file system.
622 static int
623 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
624 struct ext2_xattr_header *header)
626 struct super_block *sb = inode->i_sb;
627 struct buffer_head *new_bh = NULL;
628 int error;
630 if (header) {
631 new_bh = ext2_xattr_cache_find(inode, header);
632 if (new_bh) {
633 /* We found an identical block in the cache. */
634 if (new_bh == old_bh) {
635 ea_bdebug(new_bh, "keeping this block");
636 } else {
637 /* The old block is released after updating
638 the inode. */
639 ea_bdebug(new_bh, "reusing block");
641 error = dquot_alloc_block(inode, 1);
642 if (error) {
643 unlock_buffer(new_bh);
644 goto cleanup;
646 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);
647 ea_bdebug(new_bh, "refcount now=%d",
648 le32_to_cpu(HDR(new_bh)->h_refcount));
650 unlock_buffer(new_bh);
651 } else if (old_bh && header == HDR(old_bh)) {
652 /* Keep this block. No need to lock the block as we
653 don't need to change the reference count. */
654 new_bh = old_bh;
655 get_bh(new_bh);
656 ext2_xattr_cache_insert(new_bh);
657 } else {
658 /* We need to allocate a new block */
659 ext2_fsblk_t goal = ext2_group_first_block_no(sb,
660 EXT2_I(inode)->i_block_group);
661 int block = ext2_new_block(inode, goal, &error);
662 if (error)
663 goto cleanup;
664 ea_idebug(inode, "creating block %d", block);
666 new_bh = sb_getblk(sb, block);
667 if (!new_bh) {
668 ext2_free_blocks(inode, block, 1);
669 mark_inode_dirty(inode);
670 error = -EIO;
671 goto cleanup;
673 lock_buffer(new_bh);
674 memcpy(new_bh->b_data, header, new_bh->b_size);
675 set_buffer_uptodate(new_bh);
676 unlock_buffer(new_bh);
677 ext2_xattr_cache_insert(new_bh);
679 ext2_xattr_update_super_block(sb);
681 mark_buffer_dirty(new_bh);
682 if (IS_SYNC(inode)) {
683 sync_dirty_buffer(new_bh);
684 error = -EIO;
685 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
686 goto cleanup;
690 /* Update the inode. */
691 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
692 inode->i_ctime = CURRENT_TIME_SEC;
693 if (IS_SYNC(inode)) {
694 error = sync_inode_metadata(inode, 1);
695 /* In case sync failed due to ENOSPC the inode was actually
696 * written (only some dirty data were not) so we just proceed
697 * as if nothing happened and cleanup the unused block */
698 if (error && error != -ENOSPC) {
699 if (new_bh && new_bh != old_bh) {
700 dquot_free_block_nodirty(inode, 1);
701 mark_inode_dirty(inode);
703 goto cleanup;
705 } else
706 mark_inode_dirty(inode);
708 error = 0;
709 if (old_bh && old_bh != new_bh) {
710 struct mb_cache_entry *ce;
713 * If there was an old block and we are no longer using it,
714 * release the old block.
716 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
717 old_bh->b_blocknr);
718 lock_buffer(old_bh);
719 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
720 /* Free the old block. */
721 if (ce)
722 mb_cache_entry_free(ce);
723 ea_bdebug(old_bh, "freeing");
724 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
725 mark_inode_dirty(inode);
726 /* We let our caller release old_bh, so we
727 * need to duplicate the buffer before. */
728 get_bh(old_bh);
729 bforget(old_bh);
730 } else {
731 /* Decrement the refcount only. */
732 le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
733 if (ce)
734 mb_cache_entry_release(ce);
735 dquot_free_block_nodirty(inode, 1);
736 mark_inode_dirty(inode);
737 mark_buffer_dirty(old_bh);
738 ea_bdebug(old_bh, "refcount now=%d",
739 le32_to_cpu(HDR(old_bh)->h_refcount));
741 unlock_buffer(old_bh);
744 cleanup:
745 brelse(new_bh);
747 return error;
751 * ext2_xattr_delete_inode()
753 * Free extended attribute resources associated with this inode. This
754 * is called immediately before an inode is freed.
756 void
757 ext2_xattr_delete_inode(struct inode *inode)
759 struct buffer_head *bh = NULL;
760 struct mb_cache_entry *ce;
762 down_write(&EXT2_I(inode)->xattr_sem);
763 if (!EXT2_I(inode)->i_file_acl)
764 goto cleanup;
765 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
766 if (!bh) {
767 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
768 "inode %ld: block %d read error", inode->i_ino,
769 EXT2_I(inode)->i_file_acl);
770 goto cleanup;
772 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
773 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
774 HDR(bh)->h_blocks != cpu_to_le32(1)) {
775 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
776 "inode %ld: bad block %d", inode->i_ino,
777 EXT2_I(inode)->i_file_acl);
778 goto cleanup;
780 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr);
781 lock_buffer(bh);
782 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
783 if (ce)
784 mb_cache_entry_free(ce);
785 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
786 get_bh(bh);
787 bforget(bh);
788 unlock_buffer(bh);
789 } else {
790 le32_add_cpu(&HDR(bh)->h_refcount, -1);
791 if (ce)
792 mb_cache_entry_release(ce);
793 ea_bdebug(bh, "refcount now=%d",
794 le32_to_cpu(HDR(bh)->h_refcount));
795 unlock_buffer(bh);
796 mark_buffer_dirty(bh);
797 if (IS_SYNC(inode))
798 sync_dirty_buffer(bh);
799 dquot_free_block_nodirty(inode, 1);
801 EXT2_I(inode)->i_file_acl = 0;
803 cleanup:
804 brelse(bh);
805 up_write(&EXT2_I(inode)->xattr_sem);
809 * ext2_xattr_put_super()
811 * This is called when a file system is unmounted.
813 void
814 ext2_xattr_put_super(struct super_block *sb)
816 mb_cache_shrink(sb->s_bdev);
821 * ext2_xattr_cache_insert()
823 * Create a new entry in the extended attribute cache, and insert
824 * it unless such an entry is already in the cache.
826 * Returns 0, or a negative error number on failure.
828 static int
829 ext2_xattr_cache_insert(struct buffer_head *bh)
831 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
832 struct mb_cache_entry *ce;
833 int error;
835 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS);
836 if (!ce)
837 return -ENOMEM;
838 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
839 if (error) {
840 mb_cache_entry_free(ce);
841 if (error == -EBUSY) {
842 ea_bdebug(bh, "already in cache (%d cache entries)",
843 atomic_read(&ext2_xattr_cache->c_entry_count));
844 error = 0;
846 } else {
847 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
848 atomic_read(&ext2_xattr_cache->c_entry_count));
849 mb_cache_entry_release(ce);
851 return error;
855 * ext2_xattr_cmp()
857 * Compare two extended attribute blocks for equality.
859 * Returns 0 if the blocks are equal, 1 if they differ, and
860 * a negative error number on errors.
862 static int
863 ext2_xattr_cmp(struct ext2_xattr_header *header1,
864 struct ext2_xattr_header *header2)
866 struct ext2_xattr_entry *entry1, *entry2;
868 entry1 = ENTRY(header1+1);
869 entry2 = ENTRY(header2+1);
870 while (!IS_LAST_ENTRY(entry1)) {
871 if (IS_LAST_ENTRY(entry2))
872 return 1;
873 if (entry1->e_hash != entry2->e_hash ||
874 entry1->e_name_index != entry2->e_name_index ||
875 entry1->e_name_len != entry2->e_name_len ||
876 entry1->e_value_size != entry2->e_value_size ||
877 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
878 return 1;
879 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
880 return -EIO;
881 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
882 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
883 le32_to_cpu(entry1->e_value_size)))
884 return 1;
886 entry1 = EXT2_XATTR_NEXT(entry1);
887 entry2 = EXT2_XATTR_NEXT(entry2);
889 if (!IS_LAST_ENTRY(entry2))
890 return 1;
891 return 0;
895 * ext2_xattr_cache_find()
897 * Find an identical extended attribute block.
899 * Returns a locked buffer head to the block found, or NULL if such
900 * a block was not found or an error occurred.
902 static struct buffer_head *
903 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
905 __u32 hash = le32_to_cpu(header->h_hash);
906 struct mb_cache_entry *ce;
908 if (!header->h_hash)
909 return NULL; /* never share */
910 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
911 again:
912 ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev,
913 hash);
914 while (ce) {
915 struct buffer_head *bh;
917 if (IS_ERR(ce)) {
918 if (PTR_ERR(ce) == -EAGAIN)
919 goto again;
920 break;
923 bh = sb_bread(inode->i_sb, ce->e_block);
924 if (!bh) {
925 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
926 "inode %ld: block %ld read error",
927 inode->i_ino, (unsigned long) ce->e_block);
928 } else {
929 lock_buffer(bh);
930 if (le32_to_cpu(HDR(bh)->h_refcount) >
931 EXT2_XATTR_REFCOUNT_MAX) {
932 ea_idebug(inode, "block %ld refcount %d>%d",
933 (unsigned long) ce->e_block,
934 le32_to_cpu(HDR(bh)->h_refcount),
935 EXT2_XATTR_REFCOUNT_MAX);
936 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
937 ea_bdebug(bh, "b_count=%d",
938 atomic_read(&(bh->b_count)));
939 mb_cache_entry_release(ce);
940 return bh;
942 unlock_buffer(bh);
943 brelse(bh);
945 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
947 return NULL;
950 #define NAME_HASH_SHIFT 5
951 #define VALUE_HASH_SHIFT 16
954 * ext2_xattr_hash_entry()
956 * Compute the hash of an extended attribute.
958 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
959 struct ext2_xattr_entry *entry)
961 __u32 hash = 0;
962 char *name = entry->e_name;
963 int n;
965 for (n=0; n < entry->e_name_len; n++) {
966 hash = (hash << NAME_HASH_SHIFT) ^
967 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
968 *name++;
971 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
972 __le32 *value = (__le32 *)((char *)header +
973 le16_to_cpu(entry->e_value_offs));
974 for (n = (le32_to_cpu(entry->e_value_size) +
975 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
976 hash = (hash << VALUE_HASH_SHIFT) ^
977 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
978 le32_to_cpu(*value++);
981 entry->e_hash = cpu_to_le32(hash);
984 #undef NAME_HASH_SHIFT
985 #undef VALUE_HASH_SHIFT
987 #define BLOCK_HASH_SHIFT 16
990 * ext2_xattr_rehash()
992 * Re-compute the extended attribute hash value after an entry has changed.
994 static void ext2_xattr_rehash(struct ext2_xattr_header *header,
995 struct ext2_xattr_entry *entry)
997 struct ext2_xattr_entry *here;
998 __u32 hash = 0;
1000 ext2_xattr_hash_entry(header, entry);
1001 here = ENTRY(header+1);
1002 while (!IS_LAST_ENTRY(here)) {
1003 if (!here->e_hash) {
1004 /* Block is not shared if an entry's hash value == 0 */
1005 hash = 0;
1006 break;
1008 hash = (hash << BLOCK_HASH_SHIFT) ^
1009 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1010 le32_to_cpu(here->e_hash);
1011 here = EXT2_XATTR_NEXT(here);
1013 header->h_hash = cpu_to_le32(hash);
1016 #undef BLOCK_HASH_SHIFT
1018 int __init
1019 init_ext2_xattr(void)
1021 ext2_xattr_cache = mb_cache_create("ext2_xattr", 6);
1022 if (!ext2_xattr_cache)
1023 return -ENOMEM;
1024 return 0;
1027 void
1028 exit_ext2_xattr(void)
1030 mb_cache_destroy(ext2_xattr_cache);