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/fs/ext3/xattr.c

https://bitbucket.org/evzijst/gittest
C | 1320 lines | 1035 code | 111 blank | 174 comment | 235 complexity | 1d4075ed54301ed32810848903676bae MD5 | raw file
   1/*
   2 * linux/fs/ext3/xattr.c
   3 *
   4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5 *
   6 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
   7 * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
   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 * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
  13 *  and Andreas Gruenbacher <agruen@suse.de>.
  14 */
  15
  16/*
  17 * Extended attributes are stored directly in inodes (on file systems with
  18 * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
  19 * field contains the block number if an inode uses an additional block. All
  20 * attributes must fit in the inode and one additional block. Blocks that
  21 * contain the identical set of attributes may be shared among several inodes.
  22 * Identical blocks are detected by keeping a cache of blocks that have
  23 * recently been accessed.
  24 *
  25 * The attributes in inodes and on blocks have a different header; the entries
  26 * are stored in the same format:
  27 *
  28 *   +------------------+
  29 *   | header           |
  30 *   | entry 1          | |
  31 *   | entry 2          | | growing downwards
  32 *   | entry 3          | v
  33 *   | four null bytes  |
  34 *   | . . .            |
  35 *   | value 1          | ^
  36 *   | value 3          | | growing upwards
  37 *   | value 2          | |
  38 *   +------------------+
  39 *
  40 * The header is followed by multiple entry descriptors. In disk blocks, the
  41 * entry descriptors are kept sorted. In inodes, they are unsorted. The
  42 * attribute values are aligned to the end of the block in no specific order.
  43 *
  44 * Locking strategy
  45 * ----------------
  46 * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
  47 * EA blocks are only changed if they are exclusive to an inode, so
  48 * holding xattr_sem also means that nothing but the EA block's reference
  49 * count can change. Multiple writers to the same block are synchronized
  50 * by the buffer lock.
  51 */
  52
  53#include <linux/init.h>
  54#include <linux/fs.h>
  55#include <linux/slab.h>
  56#include <linux/ext3_jbd.h>
  57#include <linux/ext3_fs.h>
  58#include <linux/mbcache.h>
  59#include <linux/quotaops.h>
  60#include <linux/rwsem.h>
  61#include "xattr.h"
  62#include "acl.h"
  63
  64#define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
  65#define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
  66#define BFIRST(bh) ENTRY(BHDR(bh)+1)
  67#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  68
  69#define IHDR(inode, raw_inode) \
  70	((struct ext3_xattr_ibody_header *) \
  71		((void *)raw_inode + \
  72		 EXT3_GOOD_OLD_INODE_SIZE + \
  73		 EXT3_I(inode)->i_extra_isize))
  74#define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
  75
  76#ifdef EXT3_XATTR_DEBUG
  77# define ea_idebug(inode, f...) do { \
  78		printk(KERN_DEBUG "inode %s:%ld: ", \
  79			inode->i_sb->s_id, inode->i_ino); \
  80		printk(f); \
  81		printk("\n"); \
  82	} while (0)
  83# define ea_bdebug(bh, f...) do { \
  84		char b[BDEVNAME_SIZE]; \
  85		printk(KERN_DEBUG "block %s:%lu: ", \
  86			bdevname(bh->b_bdev, b), \
  87			(unsigned long) bh->b_blocknr); \
  88		printk(f); \
  89		printk("\n"); \
  90	} while (0)
  91#else
  92# define ea_idebug(f...)
  93# define ea_bdebug(f...)
  94#endif
  95
  96static void ext3_xattr_cache_insert(struct buffer_head *);
  97static struct buffer_head *ext3_xattr_cache_find(struct inode *,
  98						 struct ext3_xattr_header *,
  99						 struct mb_cache_entry **);
 100static void ext3_xattr_rehash(struct ext3_xattr_header *,
 101			      struct ext3_xattr_entry *);
 102
 103static struct mb_cache *ext3_xattr_cache;
 104
 105static struct xattr_handler *ext3_xattr_handler_map[] = {
 106	[EXT3_XATTR_INDEX_USER]		     = &ext3_xattr_user_handler,
 107#ifdef CONFIG_EXT3_FS_POSIX_ACL
 108	[EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext3_xattr_acl_access_handler,
 109	[EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
 110#endif
 111	[EXT3_XATTR_INDEX_TRUSTED]	     = &ext3_xattr_trusted_handler,
 112#ifdef CONFIG_EXT3_FS_SECURITY
 113	[EXT3_XATTR_INDEX_SECURITY]	     = &ext3_xattr_security_handler,
 114#endif
 115};
 116
 117struct xattr_handler *ext3_xattr_handlers[] = {
 118	&ext3_xattr_user_handler,
 119	&ext3_xattr_trusted_handler,
 120#ifdef CONFIG_EXT3_FS_POSIX_ACL
 121	&ext3_xattr_acl_access_handler,
 122	&ext3_xattr_acl_default_handler,
 123#endif
 124#ifdef CONFIG_EXT3_FS_SECURITY
 125	&ext3_xattr_security_handler,
 126#endif
 127	NULL
 128};
 129
 130static inline struct xattr_handler *
 131ext3_xattr_handler(int name_index)
 132{
 133	struct xattr_handler *handler = NULL;
 134
 135	if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
 136		handler = ext3_xattr_handler_map[name_index];
 137	return handler;
 138}
 139
 140/*
 141 * Inode operation listxattr()
 142 *
 143 * dentry->d_inode->i_sem: don't care
 144 */
 145ssize_t
 146ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
 147{
 148	return ext3_xattr_list(dentry->d_inode, buffer, size);
 149}
 150
 151static int
 152ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
 153{
 154	while (!IS_LAST_ENTRY(entry)) {
 155		struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
 156		if ((void *)next >= end)
 157			return -EIO;
 158		entry = next;
 159	}
 160	return 0;
 161}
 162
 163static inline int
 164ext3_xattr_check_block(struct buffer_head *bh)
 165{
 166	int error;
 167
 168	if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
 169	    BHDR(bh)->h_blocks != cpu_to_le32(1))
 170		return -EIO;
 171	error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 172	return error;
 173}
 174
 175static inline int
 176ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
 177{
 178	size_t value_size = le32_to_cpu(entry->e_value_size);
 179
 180	if (entry->e_value_block != 0 || value_size > size ||
 181	    le16_to_cpu(entry->e_value_offs) + value_size > size)
 182		return -EIO;
 183	return 0;
 184}
 185
 186static int
 187ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
 188		      const char *name, size_t size, int sorted)
 189{
 190	struct ext3_xattr_entry *entry;
 191	size_t name_len;
 192	int cmp = 1;
 193
 194	if (name == NULL)
 195		return -EINVAL;
 196	name_len = strlen(name);
 197	entry = *pentry;
 198	for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 199		cmp = name_index - entry->e_name_index;
 200		if (!cmp)
 201			cmp = name_len - entry->e_name_len;
 202		if (!cmp)
 203			cmp = memcmp(name, entry->e_name, name_len);
 204		if (cmp <= 0 && (sorted || cmp == 0))
 205			break;
 206	}
 207	*pentry = entry;
 208	if (!cmp && ext3_xattr_check_entry(entry, size))
 209			return -EIO;
 210	return cmp ? -ENODATA : 0;
 211}
 212
 213int
 214ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
 215		     void *buffer, size_t buffer_size)
 216{
 217	struct buffer_head *bh = NULL;
 218	struct ext3_xattr_entry *entry;
 219	size_t size;
 220	int error;
 221
 222	ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 223		  name_index, name, buffer, (long)buffer_size);
 224
 225	error = -ENODATA;
 226	if (!EXT3_I(inode)->i_file_acl)
 227		goto cleanup;
 228	ea_idebug(inode, "reading block %d", EXT3_I(inode)->i_file_acl);
 229	bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 230	if (!bh)
 231		goto cleanup;
 232	ea_bdebug(bh, "b_count=%d, refcount=%d",
 233		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 234	if (ext3_xattr_check_block(bh)) {
 235bad_block:	ext3_error(inode->i_sb, __FUNCTION__,
 236			   "inode %ld: bad block %d", inode->i_ino,
 237			   EXT3_I(inode)->i_file_acl);
 238		error = -EIO;
 239		goto cleanup;
 240	}
 241	ext3_xattr_cache_insert(bh);
 242	entry = BFIRST(bh);
 243	error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 244	if (error == -EIO)
 245		goto bad_block;
 246	if (error)
 247		goto cleanup;
 248	size = le32_to_cpu(entry->e_value_size);
 249	if (buffer) {
 250		error = -ERANGE;
 251		if (size > buffer_size)
 252			goto cleanup;
 253		memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 254		       size);
 255	}
 256	error = size;
 257
 258cleanup:
 259	brelse(bh);
 260	return error;
 261}
 262
 263static int
 264ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 265		     void *buffer, size_t buffer_size)
 266{
 267	struct ext3_xattr_ibody_header *header;
 268	struct ext3_xattr_entry *entry;
 269	struct ext3_inode *raw_inode;
 270	struct ext3_iloc iloc;
 271	size_t size;
 272	void *end;
 273	int error;
 274
 275	if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
 276		return -ENODATA;
 277	error = ext3_get_inode_loc(inode, &iloc);
 278	if (error)
 279		return error;
 280	raw_inode = ext3_raw_inode(&iloc);
 281	header = IHDR(inode, raw_inode);
 282	entry = IFIRST(header);
 283	end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 284	error = ext3_xattr_check_names(entry, end);
 285	if (error)
 286		goto cleanup;
 287	error = ext3_xattr_find_entry(&entry, name_index, name,
 288				      end - (void *)entry, 0);
 289	if (error)
 290		goto cleanup;
 291	size = le32_to_cpu(entry->e_value_size);
 292	if (buffer) {
 293		error = -ERANGE;
 294		if (size > buffer_size)
 295			goto cleanup;
 296		memcpy(buffer, (void *)IFIRST(header) +
 297		       le16_to_cpu(entry->e_value_offs), size);
 298	}
 299	error = size;
 300
 301cleanup:
 302	brelse(iloc.bh);
 303	return error;
 304}
 305
 306/*
 307 * ext3_xattr_get()
 308 *
 309 * Copy an extended attribute into the buffer
 310 * provided, or compute the buffer size required.
 311 * Buffer is NULL to compute the size of the buffer required.
 312 *
 313 * Returns a negative error number on failure, or the number of bytes
 314 * used / required on success.
 315 */
 316int
 317ext3_xattr_get(struct inode *inode, int name_index, const char *name,
 318	       void *buffer, size_t buffer_size)
 319{
 320	int error;
 321
 322	down_read(&EXT3_I(inode)->xattr_sem);
 323	error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
 324				     buffer_size);
 325	if (error == -ENODATA)
 326		error = ext3_xattr_block_get(inode, name_index, name, buffer,
 327					     buffer_size);
 328	up_read(&EXT3_I(inode)->xattr_sem);
 329	return error;
 330}
 331
 332static int
 333ext3_xattr_list_entries(struct inode *inode, struct ext3_xattr_entry *entry,
 334			char *buffer, size_t buffer_size)
 335{
 336	size_t rest = buffer_size;
 337
 338	for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 339		struct xattr_handler *handler =
 340			ext3_xattr_handler(entry->e_name_index);
 341
 342		if (handler) {
 343			size_t size = handler->list(inode, buffer, rest,
 344						    entry->e_name,
 345						    entry->e_name_len);
 346			if (buffer) {
 347				if (size > rest)
 348					return -ERANGE;
 349				buffer += size;
 350			}
 351			rest -= size;
 352		}
 353	}
 354	return buffer_size - rest;
 355}
 356
 357int
 358ext3_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
 359{
 360	struct buffer_head *bh = NULL;
 361	int error;
 362
 363	ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 364		  buffer, (long)buffer_size);
 365
 366	error = 0;
 367	if (!EXT3_I(inode)->i_file_acl)
 368		goto cleanup;
 369	ea_idebug(inode, "reading block %d", EXT3_I(inode)->i_file_acl);
 370	bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 371	error = -EIO;
 372	if (!bh)
 373		goto cleanup;
 374	ea_bdebug(bh, "b_count=%d, refcount=%d",
 375		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 376	if (ext3_xattr_check_block(bh)) {
 377		ext3_error(inode->i_sb, __FUNCTION__,
 378			   "inode %ld: bad block %d", inode->i_ino,
 379			   EXT3_I(inode)->i_file_acl);
 380		error = -EIO;
 381		goto cleanup;
 382	}
 383	ext3_xattr_cache_insert(bh);
 384	error = ext3_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
 385
 386cleanup:
 387	brelse(bh);
 388
 389	return error;
 390}
 391
 392static int
 393ext3_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
 394{
 395	struct ext3_xattr_ibody_header *header;
 396	struct ext3_inode *raw_inode;
 397	struct ext3_iloc iloc;
 398	void *end;
 399	int error;
 400
 401	if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
 402		return 0;
 403	error = ext3_get_inode_loc(inode, &iloc);
 404	if (error)
 405		return error;
 406	raw_inode = ext3_raw_inode(&iloc);
 407	header = IHDR(inode, raw_inode);
 408	end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 409	error = ext3_xattr_check_names(IFIRST(header), end);
 410	if (error)
 411		goto cleanup;
 412	error = ext3_xattr_list_entries(inode, IFIRST(header),
 413					buffer, buffer_size);
 414
 415cleanup:
 416	brelse(iloc.bh);
 417	return error;
 418}
 419
 420/*
 421 * ext3_xattr_list()
 422 *
 423 * Copy a list of attribute names into the buffer
 424 * provided, or compute the buffer size required.
 425 * Buffer is NULL to compute the size of the buffer required.
 426 *
 427 * Returns a negative error number on failure, or the number of bytes
 428 * used / required on success.
 429 */
 430int
 431ext3_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
 432{
 433	int i_error, b_error;
 434
 435	down_read(&EXT3_I(inode)->xattr_sem);
 436	i_error = ext3_xattr_ibody_list(inode, buffer, buffer_size);
 437	if (i_error < 0) {
 438		b_error = 0;
 439	} else {
 440		if (buffer) {
 441			buffer += i_error;
 442			buffer_size -= i_error;
 443		}
 444		b_error = ext3_xattr_block_list(inode, buffer, buffer_size);
 445		if (b_error < 0)
 446			i_error = 0;
 447	}
 448	up_read(&EXT3_I(inode)->xattr_sem);
 449	return i_error + b_error;
 450}
 451
 452/*
 453 * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 454 * not set, set it.
 455 */
 456static void ext3_xattr_update_super_block(handle_t *handle,
 457					  struct super_block *sb)
 458{
 459	if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
 460		return;
 461
 462	lock_super(sb);
 463	if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
 464		EXT3_SB(sb)->s_es->s_feature_compat |=
 465			cpu_to_le32(EXT3_FEATURE_COMPAT_EXT_ATTR);
 466		sb->s_dirt = 1;
 467		ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 468	}
 469	unlock_super(sb);
 470}
 471
 472/*
 473 * Release the xattr block BH: If the reference count is > 1, decrement
 474 * it; otherwise free the block.
 475 */
 476static void
 477ext3_xattr_release_block(handle_t *handle, struct inode *inode,
 478			 struct buffer_head *bh)
 479{
 480	struct mb_cache_entry *ce = NULL;
 481
 482	ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
 483	if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 484		ea_bdebug(bh, "refcount now=0; freeing");
 485		if (ce)
 486			mb_cache_entry_free(ce);
 487		ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
 488		get_bh(bh);
 489		ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
 490	} else {
 491		if (ext3_journal_get_write_access(handle, bh) == 0) {
 492			lock_buffer(bh);
 493			BHDR(bh)->h_refcount = cpu_to_le32(
 494				le32_to_cpu(BHDR(bh)->h_refcount) - 1);
 495			ext3_journal_dirty_metadata(handle, bh);
 496			if (IS_SYNC(inode))
 497				handle->h_sync = 1;
 498			DQUOT_FREE_BLOCK(inode, 1);
 499			unlock_buffer(bh);
 500			ea_bdebug(bh, "refcount now=%d; releasing",
 501				  le32_to_cpu(BHDR(bh)->h_refcount));
 502		}
 503		if (ce)
 504			mb_cache_entry_release(ce);
 505	}
 506}
 507
 508struct ext3_xattr_info {
 509	int name_index;
 510	const char *name;
 511	const void *value;
 512	size_t value_len;
 513};
 514
 515struct ext3_xattr_search {
 516	struct ext3_xattr_entry *first;
 517	void *base;
 518	void *end;
 519	struct ext3_xattr_entry *here;
 520	int not_found;
 521};
 522
 523static int
 524ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
 525{
 526	struct ext3_xattr_entry *last;
 527	size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 528
 529	/* Compute min_offs and last. */
 530	last = s->first;
 531	for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
 532		if (!last->e_value_block && last->e_value_size) {
 533			size_t offs = le16_to_cpu(last->e_value_offs);
 534			if (offs < min_offs)
 535				min_offs = offs;
 536		}
 537	}
 538	free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 539	if (!s->not_found) {
 540		if (!s->here->e_value_block && s->here->e_value_size) {
 541			size_t size = le32_to_cpu(s->here->e_value_size);
 542			free += EXT3_XATTR_SIZE(size);
 543		}
 544		free += EXT3_XATTR_LEN(name_len);
 545	}
 546	if (i->value) {
 547		if (free < EXT3_XATTR_SIZE(i->value_len) ||
 548		    free < EXT3_XATTR_LEN(name_len) +
 549			   EXT3_XATTR_SIZE(i->value_len))
 550			return -ENOSPC;
 551	}
 552
 553	if (i->value && s->not_found) {
 554		/* Insert the new name. */
 555		size_t size = EXT3_XATTR_LEN(name_len);
 556		size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 557		memmove((void *)s->here + size, s->here, rest);
 558		memset(s->here, 0, size);
 559		s->here->e_name_index = i->name_index;
 560		s->here->e_name_len = name_len;
 561		memcpy(s->here->e_name, i->name, name_len);
 562	} else {
 563		if (!s->here->e_value_block && s->here->e_value_size) {
 564			void *first_val = s->base + min_offs;
 565			size_t offs = le16_to_cpu(s->here->e_value_offs);
 566			void *val = s->base + offs;
 567			size_t size = EXT3_XATTR_SIZE(
 568				le32_to_cpu(s->here->e_value_size));
 569
 570			if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
 571				/* The old and the new value have the same
 572				   size. Just replace. */
 573				s->here->e_value_size =
 574					cpu_to_le32(i->value_len);
 575				memset(val + size - EXT3_XATTR_PAD, 0,
 576				       EXT3_XATTR_PAD); /* Clear pad bytes. */
 577				memcpy(val, i->value, i->value_len);
 578				return 0;
 579			}
 580
 581			/* Remove the old value. */
 582			memmove(first_val + size, first_val, val - first_val);
 583			memset(first_val, 0, size);
 584			s->here->e_value_size = 0;
 585			s->here->e_value_offs = 0;
 586			min_offs += size;
 587
 588			/* Adjust all value offsets. */
 589			last = s->first;
 590			while (!IS_LAST_ENTRY(last)) {
 591				size_t o = le16_to_cpu(last->e_value_offs);
 592				if (!last->e_value_block &&
 593				    last->e_value_size && o < offs)
 594					last->e_value_offs =
 595						cpu_to_le16(o + size);
 596				last = EXT3_XATTR_NEXT(last);
 597			}
 598		}
 599		if (!i->value) {
 600			/* Remove the old name. */
 601			size_t size = EXT3_XATTR_LEN(name_len);
 602			last = ENTRY((void *)last - size);
 603			memmove(s->here, (void *)s->here + size,
 604				(void *)last - (void *)s->here + sizeof(__u32));
 605			memset(last, 0, size);
 606		}
 607	}
 608
 609	if (i->value) {
 610		/* Insert the new value. */
 611		s->here->e_value_size = cpu_to_le32(i->value_len);
 612		if (i->value_len) {
 613			size_t size = EXT3_XATTR_SIZE(i->value_len);
 614			void *val = s->base + min_offs - size;
 615			s->here->e_value_offs = cpu_to_le16(min_offs - size);
 616			memset(val + size - EXT3_XATTR_PAD, 0,
 617			       EXT3_XATTR_PAD); /* Clear the pad bytes. */
 618			memcpy(val, i->value, i->value_len);
 619		}
 620	}
 621	return 0;
 622}
 623
 624struct ext3_xattr_block_find {
 625	struct ext3_xattr_search s;
 626	struct buffer_head *bh;
 627};
 628
 629int
 630ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
 631		      struct ext3_xattr_block_find *bs)
 632{
 633	struct super_block *sb = inode->i_sb;
 634	int error;
 635
 636	ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 637		  i->name_index, i->name, i->value, (long)i->value_len);
 638
 639	if (EXT3_I(inode)->i_file_acl) {
 640		/* The inode already has an extended attribute block. */
 641		bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
 642		error = -EIO;
 643		if (!bs->bh)
 644			goto cleanup;
 645		ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 646			atomic_read(&(bs->bh->b_count)),
 647			le32_to_cpu(BHDR(bs->bh)->h_refcount));
 648		if (ext3_xattr_check_block(bs->bh)) {
 649			ext3_error(sb, __FUNCTION__,
 650				"inode %ld: bad block %d", inode->i_ino,
 651				EXT3_I(inode)->i_file_acl);
 652			error = -EIO;
 653			goto cleanup;
 654		}
 655		/* Find the named attribute. */
 656		bs->s.base = BHDR(bs->bh);
 657		bs->s.first = BFIRST(bs->bh);
 658		bs->s.end = bs->bh->b_data + bs->bh->b_size;
 659		bs->s.here = bs->s.first;
 660		error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
 661					      i->name, bs->bh->b_size, 1);
 662		if (error && error != -ENODATA)
 663			goto cleanup;
 664		bs->s.not_found = error;
 665	}
 666	error = 0;
 667
 668cleanup:
 669	return error;
 670}
 671
 672static int
 673ext3_xattr_block_set(handle_t *handle, struct inode *inode,
 674		     struct ext3_xattr_info *i,
 675		     struct ext3_xattr_block_find *bs)
 676{
 677	struct super_block *sb = inode->i_sb;
 678	struct buffer_head *new_bh = NULL;
 679	struct ext3_xattr_search *s = &bs->s;
 680	struct mb_cache_entry *ce = NULL;
 681	int error;
 682
 683#define header(x) ((struct ext3_xattr_header *)(x))
 684
 685	if (i->value && i->value_len > sb->s_blocksize)
 686		return -ENOSPC;
 687	if (s->base) {
 688		ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
 689					bs->bh->b_blocknr);
 690		if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 691			if (ce) {
 692				mb_cache_entry_free(ce);
 693				ce = NULL;
 694			}
 695			ea_bdebug(bs->bh, "modifying in-place");
 696			error = ext3_journal_get_write_access(handle, bs->bh);
 697			if (error)
 698				goto cleanup;
 699			lock_buffer(bs->bh);
 700			error = ext3_xattr_set_entry(i, s);
 701			if (!error) {
 702				if (!IS_LAST_ENTRY(s->first))
 703					ext3_xattr_rehash(header(s->base),
 704							  s->here);
 705				ext3_xattr_cache_insert(bs->bh);
 706			}
 707			unlock_buffer(bs->bh);
 708			if (error == -EIO)
 709				goto bad_block;
 710			if (!error)
 711				error = ext3_journal_dirty_metadata(handle,
 712								    bs->bh);
 713			if (error)
 714				goto cleanup;
 715			goto inserted;
 716		} else {
 717			int offset = (char *)s->here - bs->bh->b_data;
 718
 719			if (ce) {
 720				mb_cache_entry_release(ce);
 721				ce = NULL;
 722			}
 723			ea_bdebug(bs->bh, "cloning");
 724			s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
 725			error = -ENOMEM;
 726			if (s->base == NULL)
 727				goto cleanup;
 728			memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 729			s->first = ENTRY(header(s->base)+1);
 730			header(s->base)->h_refcount = cpu_to_le32(1);
 731			s->here = ENTRY(s->base + offset);
 732			s->end = s->base + bs->bh->b_size;
 733		}
 734	} else {
 735		/* Allocate a buffer where we construct the new block. */
 736		s->base = kmalloc(sb->s_blocksize, GFP_KERNEL);
 737		/* assert(header == s->base) */
 738		error = -ENOMEM;
 739		if (s->base == NULL)
 740			goto cleanup;
 741		memset(s->base, 0, sb->s_blocksize);
 742		header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 743		header(s->base)->h_blocks = cpu_to_le32(1);
 744		header(s->base)->h_refcount = cpu_to_le32(1);
 745		s->first = ENTRY(header(s->base)+1);
 746		s->here = ENTRY(header(s->base)+1);
 747		s->end = s->base + sb->s_blocksize;
 748	}
 749
 750	error = ext3_xattr_set_entry(i, s);
 751	if (error == -EIO)
 752		goto bad_block;
 753	if (error)
 754		goto cleanup;
 755	if (!IS_LAST_ENTRY(s->first))
 756		ext3_xattr_rehash(header(s->base), s->here);
 757
 758inserted:
 759	if (!IS_LAST_ENTRY(s->first)) {
 760		new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
 761		if (new_bh) {
 762			/* We found an identical block in the cache. */
 763			if (new_bh == bs->bh)
 764				ea_bdebug(new_bh, "keeping");
 765			else {
 766				/* The old block is released after updating
 767				   the inode. */
 768				error = -EDQUOT;
 769				if (DQUOT_ALLOC_BLOCK(inode, 1))
 770					goto cleanup;
 771				error = ext3_journal_get_write_access(handle,
 772								      new_bh);
 773				if (error)
 774					goto cleanup_dquot;
 775				lock_buffer(new_bh);
 776				BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
 777					le32_to_cpu(BHDR(new_bh)->h_refcount));
 778				ea_bdebug(new_bh, "reusing; refcount now=%d",
 779					le32_to_cpu(BHDR(new_bh)->h_refcount));
 780				unlock_buffer(new_bh);
 781				error = ext3_journal_dirty_metadata(handle,
 782								    new_bh);
 783				if (error)
 784					goto cleanup_dquot;
 785			}
 786			mb_cache_entry_release(ce);
 787			ce = NULL;
 788		} else if (bs->bh && s->base == bs->bh->b_data) {
 789			/* We were modifying this block in-place. */
 790			ea_bdebug(bs->bh, "keeping this block");
 791			new_bh = bs->bh;
 792			get_bh(new_bh);
 793		} else {
 794			/* We need to allocate a new block */
 795			int goal = le32_to_cpu(
 796					EXT3_SB(sb)->s_es->s_first_data_block) +
 797				EXT3_I(inode)->i_block_group *
 798				EXT3_BLOCKS_PER_GROUP(sb);
 799			int block = ext3_new_block(handle, inode, goal, &error);
 800			if (error)
 801				goto cleanup;
 802			ea_idebug(inode, "creating block %d", block);
 803
 804			new_bh = sb_getblk(sb, block);
 805			if (!new_bh) {
 806getblk_failed:
 807				ext3_free_blocks(handle, inode, block, 1);
 808				error = -EIO;
 809				goto cleanup;
 810			}
 811			lock_buffer(new_bh);
 812			error = ext3_journal_get_create_access(handle, new_bh);
 813			if (error) {
 814				unlock_buffer(new_bh);
 815				goto getblk_failed;
 816			}
 817			memcpy(new_bh->b_data, s->base, new_bh->b_size);
 818			set_buffer_uptodate(new_bh);
 819			unlock_buffer(new_bh);
 820			ext3_xattr_cache_insert(new_bh);
 821			error = ext3_journal_dirty_metadata(handle, new_bh);
 822			if (error)
 823				goto cleanup;
 824		}
 825	}
 826
 827	/* Update the inode. */
 828	EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 829
 830	/* Drop the previous xattr block. */
 831	if (bs->bh && bs->bh != new_bh)
 832		ext3_xattr_release_block(handle, inode, bs->bh);
 833	error = 0;
 834
 835cleanup:
 836	if (ce)
 837		mb_cache_entry_release(ce);
 838	brelse(new_bh);
 839	if (!(bs->bh && s->base == bs->bh->b_data))
 840		kfree(s->base);
 841
 842	return error;
 843
 844cleanup_dquot:
 845	DQUOT_FREE_BLOCK(inode, 1);
 846	goto cleanup;
 847
 848bad_block:
 849	ext3_error(inode->i_sb, __FUNCTION__,
 850		   "inode %ld: bad block %d", inode->i_ino,
 851		   EXT3_I(inode)->i_file_acl);
 852	goto cleanup;
 853
 854#undef header
 855}
 856
 857struct ext3_xattr_ibody_find {
 858	struct ext3_xattr_search s;
 859	struct ext3_iloc iloc;
 860};
 861
 862int
 863ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
 864		      struct ext3_xattr_ibody_find *is)
 865{
 866	struct ext3_xattr_ibody_header *header;
 867	struct ext3_inode *raw_inode;
 868	int error;
 869
 870	if (EXT3_I(inode)->i_extra_isize == 0)
 871		return 0;
 872	raw_inode = ext3_raw_inode(&is->iloc);
 873	header = IHDR(inode, raw_inode);
 874	is->s.base = is->s.first = IFIRST(header);
 875	is->s.here = is->s.first;
 876	is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 877	if (EXT3_I(inode)->i_state & EXT3_STATE_XATTR) {
 878		error = ext3_xattr_check_names(IFIRST(header), is->s.end);
 879		if (error)
 880			return error;
 881		/* Find the named attribute. */
 882		error = ext3_xattr_find_entry(&is->s.here, i->name_index,
 883					      i->name, is->s.end -
 884					      (void *)is->s.base, 0);
 885		if (error && error != -ENODATA)
 886			return error;
 887		is->s.not_found = error;
 888	}
 889	return 0;
 890}
 891
 892static int
 893ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
 894		     struct ext3_xattr_info *i,
 895		     struct ext3_xattr_ibody_find *is)
 896{
 897	struct ext3_xattr_ibody_header *header;
 898	struct ext3_xattr_search *s = &is->s;
 899	int error;
 900
 901	if (EXT3_I(inode)->i_extra_isize == 0)
 902		return -ENOSPC;
 903	error = ext3_xattr_set_entry(i, s);
 904	if (error)
 905		return error;
 906	header = IHDR(inode, ext3_raw_inode(&is->iloc));
 907	if (!IS_LAST_ENTRY(s->first)) {
 908		header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 909		EXT3_I(inode)->i_state |= EXT3_STATE_XATTR;
 910	} else {
 911		header->h_magic = cpu_to_le32(0);
 912		EXT3_I(inode)->i_state &= ~EXT3_STATE_XATTR;
 913	}
 914	return 0;
 915}
 916
 917/*
 918 * ext3_xattr_set_handle()
 919 *
 920 * Create, replace or remove an extended attribute for this inode. Buffer
 921 * is NULL to remove an existing extended attribute, and non-NULL to
 922 * either replace an existing extended attribute, or create a new extended
 923 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 924 * specify that an extended attribute must exist and must not exist
 925 * previous to the call, respectively.
 926 *
 927 * Returns 0, or a negative error number on failure.
 928 */
 929int
 930ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 931		      const char *name, const void *value, size_t value_len,
 932		      int flags)
 933{
 934	struct ext3_xattr_info i = {
 935		.name_index = name_index,
 936		.name = name,
 937		.value = value,
 938		.value_len = value_len,
 939
 940	};
 941	struct ext3_xattr_ibody_find is = {
 942		.s = { .not_found = -ENODATA, },
 943	};
 944	struct ext3_xattr_block_find bs = {
 945		.s = { .not_found = -ENODATA, },
 946	};
 947	int error;
 948
 949	if (IS_RDONLY(inode))
 950		return -EROFS;
 951	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 952		return -EPERM;
 953	if (!name)
 954		return -EINVAL;
 955	if (strlen(name) > 255)
 956		return -ERANGE;
 957	down_write(&EXT3_I(inode)->xattr_sem);
 958	error = ext3_get_inode_loc(inode, &is.iloc);
 959	if (error)
 960		goto cleanup;
 961
 962	if (EXT3_I(inode)->i_state & EXT3_STATE_NEW) {
 963		struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
 964		memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
 965		EXT3_I(inode)->i_state &= ~EXT3_STATE_NEW;
 966	}
 967
 968	error = ext3_xattr_ibody_find(inode, &i, &is);
 969	if (error)
 970		goto cleanup;
 971	if (is.s.not_found)
 972		error = ext3_xattr_block_find(inode, &i, &bs);
 973	if (error)
 974		goto cleanup;
 975	if (is.s.not_found && bs.s.not_found) {
 976		error = -ENODATA;
 977		if (flags & XATTR_REPLACE)
 978			goto cleanup;
 979		error = 0;
 980		if (!value)
 981			goto cleanup;
 982	} else {
 983		error = -EEXIST;
 984		if (flags & XATTR_CREATE)
 985			goto cleanup;
 986	}
 987	error = ext3_journal_get_write_access(handle, is.iloc.bh);
 988	if (error)
 989		goto cleanup;
 990	if (!value) {
 991		if (!is.s.not_found)
 992			error = ext3_xattr_ibody_set(handle, inode, &i, &is);
 993		else if (!bs.s.not_found)
 994			error = ext3_xattr_block_set(handle, inode, &i, &bs);
 995	} else {
 996		error = ext3_xattr_ibody_set(handle, inode, &i, &is);
 997		if (!error && !bs.s.not_found) {
 998			i.value = NULL;
 999			error = ext3_xattr_block_set(handle, inode, &i, &bs);
1000		} else if (error == -ENOSPC) {
1001			error = ext3_xattr_block_set(handle, inode, &i, &bs);
1002			if (error)
1003				goto cleanup;
1004			if (!is.s.not_found) {
1005				i.value = NULL;
1006				error = ext3_xattr_ibody_set(handle, inode, &i,
1007							     &is);
1008			}
1009		}
1010	}
1011	if (!error) {
1012		ext3_xattr_update_super_block(handle, inode->i_sb);
1013		inode->i_ctime = CURRENT_TIME_SEC;
1014		error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1015		/*
1016		 * The bh is consumed by ext3_mark_iloc_dirty, even with
1017		 * error != 0.
1018		 */
1019		is.iloc.bh = NULL;
1020		if (IS_SYNC(inode))
1021			handle->h_sync = 1;
1022	}
1023
1024cleanup:
1025	brelse(is.iloc.bh);
1026	brelse(bs.bh);
1027	up_write(&EXT3_I(inode)->xattr_sem);
1028	return error;
1029}
1030
1031/*
1032 * ext3_xattr_set()
1033 *
1034 * Like ext3_xattr_set_handle, but start from an inode. This extended
1035 * attribute modification is a filesystem transaction by itself.
1036 *
1037 * Returns 0, or a negative error number on failure.
1038 */
1039int
1040ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1041	       const void *value, size_t value_len, int flags)
1042{
1043	handle_t *handle;
1044	int error, retries = 0;
1045
1046retry:
1047	handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
1048	if (IS_ERR(handle)) {
1049		error = PTR_ERR(handle);
1050	} else {
1051		int error2;
1052
1053		error = ext3_xattr_set_handle(handle, inode, name_index, name,
1054					      value, value_len, flags);
1055		error2 = ext3_journal_stop(handle);
1056		if (error == -ENOSPC &&
1057		    ext3_should_retry_alloc(inode->i_sb, &retries))
1058			goto retry;
1059		if (error == 0)
1060			error = error2;
1061	}
1062
1063	return error;
1064}
1065
1066/*
1067 * ext3_xattr_delete_inode()
1068 *
1069 * Free extended attribute resources associated with this inode. This
1070 * is called immediately before an inode is freed. We have exclusive
1071 * access to the inode.
1072 */
1073void
1074ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1075{
1076	struct buffer_head *bh = NULL;
1077
1078	if (!EXT3_I(inode)->i_file_acl)
1079		goto cleanup;
1080	bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1081	if (!bh) {
1082		ext3_error(inode->i_sb, __FUNCTION__,
1083			"inode %ld: block %d read error", inode->i_ino,
1084			EXT3_I(inode)->i_file_acl);
1085		goto cleanup;
1086	}
1087	if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1088	    BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1089		ext3_error(inode->i_sb, __FUNCTION__,
1090			"inode %ld: bad block %d", inode->i_ino,
1091			EXT3_I(inode)->i_file_acl);
1092		goto cleanup;
1093	}
1094	ext3_xattr_release_block(handle, inode, bh);
1095	EXT3_I(inode)->i_file_acl = 0;
1096
1097cleanup:
1098	brelse(bh);
1099}
1100
1101/*
1102 * ext3_xattr_put_super()
1103 *
1104 * This is called when a file system is unmounted.
1105 */
1106void
1107ext3_xattr_put_super(struct super_block *sb)
1108{
1109	mb_cache_shrink(ext3_xattr_cache, sb->s_bdev);
1110}
1111
1112/*
1113 * ext3_xattr_cache_insert()
1114 *
1115 * Create a new entry in the extended attribute cache, and insert
1116 * it unless such an entry is already in the cache.
1117 *
1118 * Returns 0, or a negative error number on failure.
1119 */
1120static void
1121ext3_xattr_cache_insert(struct buffer_head *bh)
1122{
1123	__u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1124	struct mb_cache_entry *ce;
1125	int error;
1126
1127	ce = mb_cache_entry_alloc(ext3_xattr_cache);
1128	if (!ce) {
1129		ea_bdebug(bh, "out of memory");
1130		return;
1131	}
1132	error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1133	if (error) {
1134		mb_cache_entry_free(ce);
1135		if (error == -EBUSY) {
1136			ea_bdebug(bh, "already in cache");
1137			error = 0;
1138		}
1139	} else {
1140		ea_bdebug(bh, "inserting [%x]", (int)hash);
1141		mb_cache_entry_release(ce);
1142	}
1143}
1144
1145/*
1146 * ext3_xattr_cmp()
1147 *
1148 * Compare two extended attribute blocks for equality.
1149 *
1150 * Returns 0 if the blocks are equal, 1 if they differ, and
1151 * a negative error number on errors.
1152 */
1153static int
1154ext3_xattr_cmp(struct ext3_xattr_header *header1,
1155	       struct ext3_xattr_header *header2)
1156{
1157	struct ext3_xattr_entry *entry1, *entry2;
1158
1159	entry1 = ENTRY(header1+1);
1160	entry2 = ENTRY(header2+1);
1161	while (!IS_LAST_ENTRY(entry1)) {
1162		if (IS_LAST_ENTRY(entry2))
1163			return 1;
1164		if (entry1->e_hash != entry2->e_hash ||
1165		    entry1->e_name_index != entry2->e_name_index ||
1166		    entry1->e_name_len != entry2->e_name_len ||
1167		    entry1->e_value_size != entry2->e_value_size ||
1168		    memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1169			return 1;
1170		if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1171			return -EIO;
1172		if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1173			   (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1174			   le32_to_cpu(entry1->e_value_size)))
1175			return 1;
1176
1177		entry1 = EXT3_XATTR_NEXT(entry1);
1178		entry2 = EXT3_XATTR_NEXT(entry2);
1179	}
1180	if (!IS_LAST_ENTRY(entry2))
1181		return 1;
1182	return 0;
1183}
1184
1185/*
1186 * ext3_xattr_cache_find()
1187 *
1188 * Find an identical extended attribute block.
1189 *
1190 * Returns a pointer to the block found, or NULL if such a block was
1191 * not found or an error occurred.
1192 */
1193static struct buffer_head *
1194ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1195		      struct mb_cache_entry **pce)
1196{
1197	__u32 hash = le32_to_cpu(header->h_hash);
1198	struct mb_cache_entry *ce;
1199
1200	if (!header->h_hash)
1201		return NULL;  /* never share */
1202	ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1203again:
1204	ce = mb_cache_entry_find_first(ext3_xattr_cache, 0,
1205				       inode->i_sb->s_bdev, hash);
1206	while (ce) {
1207		struct buffer_head *bh;
1208
1209		if (IS_ERR(ce)) {
1210			if (PTR_ERR(ce) == -EAGAIN)
1211				goto again;
1212			break;
1213		}
1214		bh = sb_bread(inode->i_sb, ce->e_block);
1215		if (!bh) {
1216			ext3_error(inode->i_sb, __FUNCTION__,
1217				"inode %ld: block %ld read error",
1218				inode->i_ino, (unsigned long) ce->e_block);
1219		} else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1220				EXT3_XATTR_REFCOUNT_MAX) {
1221			ea_idebug(inode, "block %ld refcount %d>=%d",
1222				  (unsigned long) ce->e_block,
1223				  le32_to_cpu(BHDR(bh)->h_refcount),
1224					  EXT3_XATTR_REFCOUNT_MAX);
1225		} else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1226			*pce = ce;
1227			return bh;
1228		}
1229		brelse(bh);
1230		ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1231	}
1232	return NULL;
1233}
1234
1235#define NAME_HASH_SHIFT 5
1236#define VALUE_HASH_SHIFT 16
1237
1238/*
1239 * ext3_xattr_hash_entry()
1240 *
1241 * Compute the hash of an extended attribute.
1242 */
1243static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1244					 struct ext3_xattr_entry *entry)
1245{
1246	__u32 hash = 0;
1247	char *name = entry->e_name;
1248	int n;
1249
1250	for (n=0; n < entry->e_name_len; n++) {
1251		hash = (hash << NAME_HASH_SHIFT) ^
1252		       (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1253		       *name++;
1254	}
1255
1256	if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1257		__le32 *value = (__le32 *)((char *)header +
1258			le16_to_cpu(entry->e_value_offs));
1259		for (n = (le32_to_cpu(entry->e_value_size) +
1260		     EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1261			hash = (hash << VALUE_HASH_SHIFT) ^
1262			       (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1263			       le32_to_cpu(*value++);
1264		}
1265	}
1266	entry->e_hash = cpu_to_le32(hash);
1267}
1268
1269#undef NAME_HASH_SHIFT
1270#undef VALUE_HASH_SHIFT
1271
1272#define BLOCK_HASH_SHIFT 16
1273
1274/*
1275 * ext3_xattr_rehash()
1276 *
1277 * Re-compute the extended attribute hash value after an entry has changed.
1278 */
1279static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1280			      struct ext3_xattr_entry *entry)
1281{
1282	struct ext3_xattr_entry *here;
1283	__u32 hash = 0;
1284
1285	ext3_xattr_hash_entry(header, entry);
1286	here = ENTRY(header+1);
1287	while (!IS_LAST_ENTRY(here)) {
1288		if (!here->e_hash) {
1289			/* Block is not shared if an entry's hash value == 0 */
1290			hash = 0;
1291			break;
1292		}
1293		hash = (hash << BLOCK_HASH_SHIFT) ^
1294		       (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1295		       le32_to_cpu(here->e_hash);
1296		here = EXT3_XATTR_NEXT(here);
1297	}
1298	header->h_hash = cpu_to_le32(hash);
1299}
1300
1301#undef BLOCK_HASH_SHIFT
1302
1303int __init
1304init_ext3_xattr(void)
1305{
1306	ext3_xattr_cache = mb_cache_create("ext3_xattr", NULL,
1307		sizeof(struct mb_cache_entry) +
1308		sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1309	if (!ext3_xattr_cache)
1310		return -ENOMEM;
1311	return 0;
1312}
1313
1314void
1315exit_ext3_xattr(void)
1316{
1317	if (ext3_xattr_cache)
1318		mb_cache_destroy(ext3_xattr_cache);
1319	ext3_xattr_cache = NULL;
1320}