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>,
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 * +------------------+
28 * | entry 2 | | growing downwards
33 * | value 3 | | growing upwards
35 * +------------------+
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.
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.
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
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/vs_dlimit.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); \
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); \
89 # define ea_idebug(f...)
90 # define ea_bdebug(f...)
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 struct xattr_handler *ext2_xattr_handler_map[EXT2_XATTR_INDEX_MAX] = {
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,
110 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,
111 #ifdef CONFIG_EXT2_FS_SECURITY
112 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,
116 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,
123 #ifdef CONFIG_EXT2_FS_SECURITY
124 &ext2_xattr_security_handler,
129 static inline struct xattr_handler *
130 ext2_xattr_handler(int name_index)
132 struct xattr_handler *handler = NULL;
134 if (name_index > 0 && name_index <= EXT2_XATTR_INDEX_MAX)
135 handler = ext2_xattr_handler_map[name_index];
140 * Inode operation listxattr()
142 * dentry->d_inode->i_sem: don't care
145 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)
147 return ext2_xattr_list(dentry->d_inode, buffer, size);
153 * Copy an extended attribute into the buffer
154 * provided, or compute the buffer size required.
155 * Buffer is NULL to compute the size of the buffer required.
157 * Returns a negative error number on failure, or the number of bytes
158 * used / required on success.
161 ext2_xattr_get(struct inode *inode, int name_index, const char *name,
162 void *buffer, size_t buffer_size)
164 struct buffer_head *bh = NULL;
165 struct ext2_xattr_entry *entry;
166 size_t name_len, size;
170 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
171 name_index, name, buffer, (long)buffer_size);
175 down_read(&EXT2_I(inode)->xattr_sem);
177 if (!EXT2_I(inode)->i_file_acl)
179 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
180 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
184 ea_bdebug(bh, "b_count=%d, refcount=%d",
185 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
186 end = bh->b_data + bh->b_size;
187 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
188 HDR(bh)->h_blocks != cpu_to_le32(1)) {
189 bad_block: ext2_error(inode->i_sb, "ext2_xattr_get",
190 "inode %ld: bad block %d", inode->i_ino,
191 EXT2_I(inode)->i_file_acl);
195 /* find named attribute */
196 name_len = strlen(name);
201 entry = FIRST_ENTRY(bh);
202 while (!IS_LAST_ENTRY(entry)) {
203 struct ext2_xattr_entry *next =
204 EXT2_XATTR_NEXT(entry);
205 if ((char *)next >= end)
207 if (name_index == entry->e_name_index &&
208 name_len == entry->e_name_len &&
209 memcmp(name, entry->e_name, name_len) == 0)
213 /* Check the remaining name entries */
214 while (!IS_LAST_ENTRY(entry)) {
215 struct ext2_xattr_entry *next =
216 EXT2_XATTR_NEXT(entry);
217 if ((char *)next >= end)
221 if (ext2_xattr_cache_insert(bh))
222 ea_idebug(inode, "cache insert failed");
226 /* check the buffer size */
227 if (entry->e_value_block != 0)
229 size = le32_to_cpu(entry->e_value_size);
230 if (size > inode->i_sb->s_blocksize ||
231 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize)
234 if (ext2_xattr_cache_insert(bh))
235 ea_idebug(inode, "cache insert failed");
238 if (size > buffer_size)
240 /* return value of attribute */
241 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
248 up_read(&EXT2_I(inode)->xattr_sem);
256 * Copy a list of attribute names into the buffer
257 * provided, or compute the buffer size required.
258 * Buffer is NULL to compute the size of the buffer required.
260 * Returns a negative error number on failure, or the number of bytes
261 * used / required on success.
264 ext2_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
266 struct buffer_head *bh = NULL;
267 struct ext2_xattr_entry *entry;
269 size_t rest = buffer_size;
272 ea_idebug(inode, "buffer=%p, buffer_size=%ld",
273 buffer, (long)buffer_size);
275 down_read(&EXT2_I(inode)->xattr_sem);
277 if (!EXT2_I(inode)->i_file_acl)
279 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);
280 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
284 ea_bdebug(bh, "b_count=%d, refcount=%d",
285 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
286 end = bh->b_data + bh->b_size;
287 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
288 HDR(bh)->h_blocks != cpu_to_le32(1)) {
289 bad_block: ext2_error(inode->i_sb, "ext2_xattr_list",
290 "inode %ld: bad block %d", inode->i_ino,
291 EXT2_I(inode)->i_file_acl);
296 /* check the on-disk data structure */
297 entry = FIRST_ENTRY(bh);
298 while (!IS_LAST_ENTRY(entry)) {
299 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry);
301 if ((char *)next >= end)
305 if (ext2_xattr_cache_insert(bh))
306 ea_idebug(inode, "cache insert failed");
308 /* list the attribute names */
309 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);
310 entry = EXT2_XATTR_NEXT(entry)) {
311 struct xattr_handler *handler =
312 ext2_xattr_handler(entry->e_name_index);
315 size_t size = handler->list(inode, buffer, rest,
328 error = buffer_size - rest; /* total size */
332 up_read(&EXT2_I(inode)->xattr_sem);
338 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is
341 static void ext2_xattr_update_super_block(struct super_block *sb)
343 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
347 EXT2_SB(sb)->s_es->s_feature_compat |=
348 cpu_to_le32(EXT2_FEATURE_COMPAT_EXT_ATTR);
350 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
357 * Create, replace or remove an extended attribute for this inode. Buffer
358 * is NULL to remove an existing extended attribute, and non-NULL to
359 * either replace an existing extended attribute, or create a new extended
360 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
361 * specify that an extended attribute must exist and must not exist
362 * previous to the call, respectively.
364 * Returns 0, or a negative error number on failure.
367 ext2_xattr_set(struct inode *inode, int name_index, const char *name,
368 const void *value, size_t value_len, int flags)
370 struct super_block *sb = inode->i_sb;
371 struct buffer_head *bh = NULL;
372 struct ext2_xattr_header *header = NULL;
373 struct ext2_xattr_entry *here, *last;
374 size_t name_len, free, min_offs = sb->s_blocksize;
375 int not_found = 1, error;
379 * header -- Points either into bh, or to a temporarily
381 * here -- The named entry found, or the place for inserting, within
382 * the block pointed to by header.
383 * last -- Points right after the last named entry within the block
384 * pointed to by header.
385 * min_offs -- The offset of the first value (values are aligned
386 * towards the end of the block).
387 * end -- Points right after the block pointed to by header.
390 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
391 name_index, name, value, (long)value_len);
393 if (IS_RDONLY(inode))
395 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
401 name_len = strlen(name);
402 if (name_len > 255 || value_len > sb->s_blocksize)
404 down_write(&EXT2_I(inode)->xattr_sem);
405 if (EXT2_I(inode)->i_file_acl) {
406 /* The inode already has an extended attribute block. */
407 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);
411 ea_bdebug(bh, "b_count=%d, refcount=%d",
412 atomic_read(&(bh->b_count)),
413 le32_to_cpu(HDR(bh)->h_refcount));
415 end = bh->b_data + bh->b_size;
416 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
417 header->h_blocks != cpu_to_le32(1)) {
418 bad_block: ext2_error(sb, "ext2_xattr_set",
419 "inode %ld: bad block %d", inode->i_ino,
420 EXT2_I(inode)->i_file_acl);
424 /* Find the named attribute. */
425 here = FIRST_ENTRY(bh);
426 while (!IS_LAST_ENTRY(here)) {
427 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here);
428 if ((char *)next >= end)
430 if (!here->e_value_block && here->e_value_size) {
431 size_t offs = le16_to_cpu(here->e_value_offs);
435 not_found = name_index - here->e_name_index;
437 not_found = name_len - here->e_name_len;
439 not_found = memcmp(name, here->e_name,name_len);
445 /* We still need to compute min_offs and last. */
446 while (!IS_LAST_ENTRY(last)) {
447 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last);
448 if ((char *)next >= end)
450 if (!last->e_value_block && last->e_value_size) {
451 size_t offs = le16_to_cpu(last->e_value_offs);
458 /* Check whether we have enough space left. */
459 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);
461 /* We will use a new extended attribute block. */
462 free = sb->s_blocksize -
463 sizeof(struct ext2_xattr_header) - sizeof(__u32);
464 here = last = NULL; /* avoid gcc uninitialized warning. */
468 /* Request to remove a nonexistent attribute? */
470 if (flags & XATTR_REPLACE)
476 /* Request to create an existing attribute? */
478 if (flags & XATTR_CREATE)
480 if (!here->e_value_block && here->e_value_size) {
481 size_t size = le32_to_cpu(here->e_value_size);
483 if (le16_to_cpu(here->e_value_offs) + size >
484 sb->s_blocksize || size > sb->s_blocksize)
486 free += EXT2_XATTR_SIZE(size);
488 free += EXT2_XATTR_LEN(name_len);
491 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))
494 /* Here we know that we can set the new attribute. */
497 struct mb_cache_entry *ce;
498 /* assert(header == HDR(bh)); */
499 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
502 if (header->h_refcount == cpu_to_le32(1)) {
503 ea_bdebug(bh, "modifying in-place");
505 mb_cache_entry_free(ce);
506 /* keep the buffer locked while modifying it. */
511 mb_cache_entry_release(ce);
513 ea_bdebug(bh, "cloning");
514 header = kmalloc(bh->b_size, GFP_KERNEL);
518 memcpy(header, HDR(bh), bh->b_size);
519 header->h_refcount = cpu_to_le32(1);
521 offset = (char *)here - bh->b_data;
522 here = ENTRY((char *)header + offset);
523 offset = (char *)last - bh->b_data;
524 last = ENTRY((char *)header + offset);
527 /* Allocate a buffer where we construct the new block. */
528 header = kmalloc(sb->s_blocksize, GFP_KERNEL);
532 memset(header, 0, sb->s_blocksize);
533 end = (char *)header + sb->s_blocksize;
534 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);
535 header->h_blocks = header->h_refcount = cpu_to_le32(1);
536 last = here = ENTRY(header+1);
539 /* Iff we are modifying the block in-place, bh is locked here. */
542 /* Insert the new name. */
543 size_t size = EXT2_XATTR_LEN(name_len);
544 size_t rest = (char *)last - (char *)here;
545 memmove((char *)here + size, here, rest);
546 memset(here, 0, size);
547 here->e_name_index = name_index;
548 here->e_name_len = name_len;
549 memcpy(here->e_name, name, name_len);
551 if (!here->e_value_block && here->e_value_size) {
552 char *first_val = (char *)header + min_offs;
553 size_t offs = le16_to_cpu(here->e_value_offs);
554 char *val = (char *)header + offs;
555 size_t size = EXT2_XATTR_SIZE(
556 le32_to_cpu(here->e_value_size));
558 if (size == EXT2_XATTR_SIZE(value_len)) {
559 /* The old and the new value have the same
560 size. Just replace. */
561 here->e_value_size = cpu_to_le32(value_len);
562 memset(val + size - EXT2_XATTR_PAD, 0,
563 EXT2_XATTR_PAD); /* Clear pad bytes. */
564 memcpy(val, value, value_len);
568 /* Remove the old value. */
569 memmove(first_val + size, first_val, val - first_val);
570 memset(first_val, 0, size);
571 here->e_value_offs = 0;
574 /* Adjust all value offsets. */
575 last = ENTRY(header+1);
576 while (!IS_LAST_ENTRY(last)) {
577 size_t o = le16_to_cpu(last->e_value_offs);
578 if (!last->e_value_block && o < offs)
580 cpu_to_le16(o + size);
581 last = EXT2_XATTR_NEXT(last);
585 /* Remove the old name. */
586 size_t size = EXT2_XATTR_LEN(name_len);
587 last = ENTRY((char *)last - size);
588 memmove(here, (char*)here + size,
589 (char*)last - (char*)here);
590 memset(last, 0, size);
595 /* Insert the new value. */
596 here->e_value_size = cpu_to_le32(value_len);
598 size_t size = EXT2_XATTR_SIZE(value_len);
599 char *val = (char *)header + min_offs - size;
601 cpu_to_le16((char *)val - (char *)header);
602 memset(val + size - EXT2_XATTR_PAD, 0,
603 EXT2_XATTR_PAD); /* Clear the pad bytes. */
604 memcpy(val, value, value_len);
609 if (IS_LAST_ENTRY(ENTRY(header+1))) {
610 /* This block is now empty. */
611 if (bh && header == HDR(bh))
612 unlock_buffer(bh); /* we were modifying in-place. */
613 error = ext2_xattr_set2(inode, bh, NULL);
615 ext2_xattr_rehash(header, here);
616 if (bh && header == HDR(bh))
617 unlock_buffer(bh); /* we were modifying in-place. */
618 error = ext2_xattr_set2(inode, bh, header);
623 if (!(bh && header == HDR(bh)))
625 up_write(&EXT2_I(inode)->xattr_sem);
631 * Second half of ext2_xattr_set(): Update the file system.
634 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
635 struct ext2_xattr_header *header)
637 struct super_block *sb = inode->i_sb;
638 struct buffer_head *new_bh = NULL;
642 new_bh = ext2_xattr_cache_find(inode, header);
644 /* We found an identical block in the cache. */
645 if (new_bh == old_bh) {
646 ea_bdebug(new_bh, "keeping this block");
648 /* The old block is released after updating
650 ea_bdebug(new_bh, "reusing block");
653 if (DLIMIT_ALLOC_BLOCK(sb, inode->i_xid, 1))
656 if (DQUOT_ALLOC_BLOCK(inode, 1)) {
657 DLIMIT_FREE_BLOCK(sb, inode->i_xid, 1);
658 unlock_buffer(new_bh);
661 HDR(new_bh)->h_refcount = cpu_to_le32(1 +
662 le32_to_cpu(HDR(new_bh)->h_refcount));
663 ea_bdebug(new_bh, "refcount now=%d",
664 le32_to_cpu(HDR(new_bh)->h_refcount));
666 unlock_buffer(new_bh);
667 } else if (old_bh && header == HDR(old_bh)) {
668 /* Keep this block. No need to lock the block as we
669 don't need to change the reference count. */
672 ext2_xattr_cache_insert(new_bh);
674 /* We need to allocate a new block */
675 int goal = le32_to_cpu(EXT2_SB(sb)->s_es->
676 s_first_data_block) +
677 EXT2_I(inode)->i_block_group *
678 EXT2_BLOCKS_PER_GROUP(sb);
679 int block = ext2_new_block(inode, goal,
683 ea_idebug(inode, "creating block %d", block);
685 new_bh = sb_getblk(sb, block);
687 ext2_free_blocks(inode, block, 1);
692 memcpy(new_bh->b_data, header, new_bh->b_size);
693 set_buffer_uptodate(new_bh);
694 unlock_buffer(new_bh);
695 ext2_xattr_cache_insert(new_bh);
697 ext2_xattr_update_super_block(sb);
699 mark_buffer_dirty(new_bh);
700 if (IS_SYNC(inode)) {
701 sync_dirty_buffer(new_bh);
703 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))
708 /* Update the inode. */
709 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
710 inode->i_ctime = CURRENT_TIME;
711 if (IS_SYNC(inode)) {
712 error = ext2_sync_inode (inode);
716 mark_inode_dirty(inode);
719 if (old_bh && old_bh != new_bh) {
720 struct mb_cache_entry *ce;
722 * If there was an old block and we are no longer using it,
723 * release the old block.
725 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev,
728 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) {
729 /* Free the old block. */
731 mb_cache_entry_free(ce);
732 ea_bdebug(old_bh, "freeing");
733 ext2_free_blocks(inode, old_bh->b_blocknr, 1);
734 /* We let our caller release old_bh, so we
735 * need to duplicate the buffer before. */
739 /* Decrement the refcount only. */
741 mb_cache_entry_release(ce);
742 HDR(old_bh)->h_refcount = cpu_to_le32(
743 le32_to_cpu(HDR(old_bh)->h_refcount) - 1);
744 DLIMIT_FREE_BLOCK(sb, inode->i_xid, 1);
745 DQUOT_FREE_BLOCK(inode, 1);
746 mark_buffer_dirty(old_bh);
747 ea_bdebug(old_bh, "refcount now=%d",
748 le32_to_cpu(HDR(old_bh)->h_refcount));
750 unlock_buffer(old_bh);
760 * ext2_xattr_delete_inode()
762 * Free extended attribute resources associated with this inode. This
763 * is called immediately before an inode is freed.
766 ext2_xattr_delete_inode(struct inode *inode)
768 struct buffer_head *bh = NULL;
769 struct mb_cache_entry *ce;
771 down_write(&EXT2_I(inode)->xattr_sem);
772 if (!EXT2_I(inode)->i_file_acl)
774 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);
776 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
777 "inode %ld: block %d read error", inode->i_ino,
778 EXT2_I(inode)->i_file_acl);
781 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
782 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
783 HDR(bh)->h_blocks != cpu_to_le32(1)) {
784 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
785 "inode %ld: bad block %d", inode->i_ino,
786 EXT2_I(inode)->i_file_acl);
789 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev,
792 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {
794 mb_cache_entry_free(ce);
795 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
800 mb_cache_entry_release(ce);
801 HDR(bh)->h_refcount = cpu_to_le32(
802 le32_to_cpu(HDR(bh)->h_refcount) - 1);
803 mark_buffer_dirty(bh);
805 sync_dirty_buffer(bh);
806 DLIMIT_FREE_BLOCK(inode->i_sb, inode->i_xid, 1);
807 DQUOT_FREE_BLOCK(inode, 1);
809 ea_bdebug(bh, "refcount now=%d", le32_to_cpu(HDR(bh)->h_refcount) - 1);
811 EXT2_I(inode)->i_file_acl = 0;
815 up_write(&EXT2_I(inode)->xattr_sem);
819 * ext2_xattr_put_super()
821 * This is called when a file system is unmounted.
824 ext2_xattr_put_super(struct super_block *sb)
826 mb_cache_shrink(ext2_xattr_cache, sb->s_bdev);
831 * ext2_xattr_cache_insert()
833 * Create a new entry in the extended attribute cache, and insert
834 * it unless such an entry is already in the cache.
836 * Returns 0, or a negative error number on failure.
839 ext2_xattr_cache_insert(struct buffer_head *bh)
841 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);
842 struct mb_cache_entry *ce;
845 ce = mb_cache_entry_alloc(ext2_xattr_cache);
848 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
850 mb_cache_entry_free(ce);
851 if (error == -EBUSY) {
852 ea_bdebug(bh, "already in cache (%d cache entries)",
853 atomic_read(&ext2_xattr_cache->c_entry_count));
857 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash,
858 atomic_read(&ext2_xattr_cache->c_entry_count));
859 mb_cache_entry_release(ce);
867 * Compare two extended attribute blocks for equality.
869 * Returns 0 if the blocks are equal, 1 if they differ, and
870 * a negative error number on errors.
873 ext2_xattr_cmp(struct ext2_xattr_header *header1,
874 struct ext2_xattr_header *header2)
876 struct ext2_xattr_entry *entry1, *entry2;
878 entry1 = ENTRY(header1+1);
879 entry2 = ENTRY(header2+1);
880 while (!IS_LAST_ENTRY(entry1)) {
881 if (IS_LAST_ENTRY(entry2))
883 if (entry1->e_hash != entry2->e_hash ||
884 entry1->e_name_len != entry2->e_name_len ||
885 entry1->e_value_size != entry2->e_value_size ||
886 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
888 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
890 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
891 (char *)header2 + le16_to_cpu(entry2->e_value_offs),
892 le32_to_cpu(entry1->e_value_size)))
895 entry1 = EXT2_XATTR_NEXT(entry1);
896 entry2 = EXT2_XATTR_NEXT(entry2);
898 if (!IS_LAST_ENTRY(entry2))
904 * ext2_xattr_cache_find()
906 * Find an identical extended attribute block.
908 * Returns a locked buffer head to the block found, or NULL if such
909 * a block was not found or an error occurred.
911 static struct buffer_head *
912 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)
914 __u32 hash = le32_to_cpu(header->h_hash);
915 struct mb_cache_entry *ce;
918 return NULL; /* never share */
919 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
921 ce = mb_cache_entry_find_first(ext2_xattr_cache, 0,
922 inode->i_sb->s_bdev, hash);
924 struct buffer_head *bh;
927 if (PTR_ERR(ce) == -EAGAIN)
932 bh = sb_bread(inode->i_sb, ce->e_block);
935 ext2_error(inode->i_sb, "ext2_xattr_cache_find",
936 "inode %ld: block %ld read error",
937 inode->i_ino, (unsigned long) ce->e_block);
940 if (le32_to_cpu(HDR(bh)->h_refcount) >
941 EXT2_XATTR_REFCOUNT_MAX) {
942 ea_idebug(inode, "block %ld refcount %d>%d",
943 (unsigned long) ce->e_block,
944 le32_to_cpu(HDR(bh)->h_refcount),
945 EXT2_XATTR_REFCOUNT_MAX);
946 } else if (!ext2_xattr_cmp(header, HDR(bh))) {
947 ea_bdebug(bh, "b_count=%d",
948 atomic_read(&(bh->b_count)));
949 mb_cache_entry_release(ce);
955 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
960 #define NAME_HASH_SHIFT 5
961 #define VALUE_HASH_SHIFT 16
964 * ext2_xattr_hash_entry()
966 * Compute the hash of an extended attribute.
968 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,
969 struct ext2_xattr_entry *entry)
972 char *name = entry->e_name;
975 for (n=0; n < entry->e_name_len; n++) {
976 hash = (hash << NAME_HASH_SHIFT) ^
977 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
981 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
982 __le32 *value = (__le32 *)((char *)header +
983 le16_to_cpu(entry->e_value_offs));
984 for (n = (le32_to_cpu(entry->e_value_size) +
985 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {
986 hash = (hash << VALUE_HASH_SHIFT) ^
987 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
988 le32_to_cpu(*value++);
991 entry->e_hash = cpu_to_le32(hash);
994 #undef NAME_HASH_SHIFT
995 #undef VALUE_HASH_SHIFT
997 #define BLOCK_HASH_SHIFT 16
1000 * ext2_xattr_rehash()
1002 * Re-compute the extended attribute hash value after an entry has changed.
1004 static void ext2_xattr_rehash(struct ext2_xattr_header *header,
1005 struct ext2_xattr_entry *entry)
1007 struct ext2_xattr_entry *here;
1010 ext2_xattr_hash_entry(header, entry);
1011 here = ENTRY(header+1);
1012 while (!IS_LAST_ENTRY(here)) {
1013 if (!here->e_hash) {
1014 /* Block is not shared if an entry's hash value == 0 */
1018 hash = (hash << BLOCK_HASH_SHIFT) ^
1019 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1020 le32_to_cpu(here->e_hash);
1021 here = EXT2_XATTR_NEXT(here);
1023 header->h_hash = cpu_to_le32(hash);
1026 #undef BLOCK_HASH_SHIFT
1029 init_ext2_xattr(void)
1031 ext2_xattr_cache = mb_cache_create("ext2_xattr", NULL,
1032 sizeof(struct mb_cache_entry) +
1033 sizeof(struct mb_cache_entry_index), 1, 6);
1034 if (!ext2_xattr_cache)
1040 exit_ext2_xattr(void)
1042 mb_cache_destroy(ext2_xattr_cache);