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1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/ext2/xattr.c4 *5 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de>6 *7 * Fix by Harrison Xing <harrison@mountainviewdata.com>.8 * Extended attributes for symlinks and special files added per9 * suggestion of Luka Renko <luka.renko@hermes.si>.10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,11 * Red Hat Inc.12 *13 */14 15/*16 * Extended attributes are stored on disk blocks allocated outside of17 * any inode. The i_file_acl field is then made to point to this allocated18 * block. If all extended attributes of an inode are identical, these19 * inodes may share the same extended attribute block. Such situations20 * are automatically detected by keeping a cache of recent attribute block21 * numbers and hashes over the block's contents in memory.22 *23 *24 * Extended attribute block layout:25 *26 * +------------------+27 * | header |28 * | entry 1 | |29 * | entry 2 | | growing downwards30 * | entry 3 | v31 * | four null bytes |32 * | . . . |33 * | value 1 | ^34 * | value 3 | | growing upwards35 * | value 2 | |36 * +------------------+37 *38 * The block header is followed by multiple entry descriptors. These entry39 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD40 * byte boundaries. The entry descriptors are sorted by attribute name,41 * so that two extended attribute blocks can be compared efficiently.42 *43 * Attribute values are aligned to the end of the block, stored in44 * no specific order. They are also padded to EXT2_XATTR_PAD byte45 * boundaries. No additional gaps are left between them.46 *47 * Locking strategy48 * ----------------49 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem.50 * EA blocks are only changed if they are exclusive to an inode, so51 * holding xattr_sem also means that nothing but the EA block's reference52 * count will change. Multiple writers to an EA block are synchronized53 * by the bh lock. No more than a single bh lock is held at any time54 * to avoid deadlocks.55 */56 57#include <linux/buffer_head.h>58#include <linux/init.h>59#include <linux/printk.h>60#include <linux/slab.h>61#include <linux/mbcache.h>62#include <linux/quotaops.h>63#include <linux/rwsem.h>64#include <linux/security.h>65#include "ext2.h"66#include "xattr.h"67#include "acl.h"68 69#define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data))70#define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr))71#define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1)72#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)73 74#ifdef EXT2_XATTR_DEBUG75# define ea_idebug(inode, f...) do { \76 printk(KERN_DEBUG "inode %s:%ld: ", \77 inode->i_sb->s_id, inode->i_ino); \78 printk(f); \79 printk("\n"); \80 } while (0)81# define ea_bdebug(bh, f...) do { \82 printk(KERN_DEBUG "block %pg:%lu: ", \83 bh->b_bdev, (unsigned long) bh->b_blocknr); \84 printk(f); \85 printk("\n"); \86 } while (0)87#else88# define ea_idebug(inode, f...) no_printk(f)89# define ea_bdebug(bh, f...) no_printk(f)90#endif91 92static int ext2_xattr_set2(struct inode *, struct buffer_head *,93 struct ext2_xattr_header *);94 95static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *);96static struct buffer_head *ext2_xattr_cache_find(struct inode *,97 struct ext2_xattr_header *);98static void ext2_xattr_rehash(struct ext2_xattr_header *,99 struct ext2_xattr_entry *);100 101static const struct xattr_handler * const ext2_xattr_handler_map[] = {102 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler,103#ifdef CONFIG_EXT2_FS_POSIX_ACL104 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &nop_posix_acl_access,105 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &nop_posix_acl_default,106#endif107 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler,108#ifdef CONFIG_EXT2_FS_SECURITY109 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler,110#endif111};112 113const struct xattr_handler * const ext2_xattr_handlers[] = {114 &ext2_xattr_user_handler,115 &ext2_xattr_trusted_handler,116#ifdef CONFIG_EXT2_FS_SECURITY117 &ext2_xattr_security_handler,118#endif119 NULL120};121 122#define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache)123 124static inline const char *ext2_xattr_prefix(int name_index,125 struct dentry *dentry)126{127 const struct xattr_handler *handler = NULL;128 129 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map))130 handler = ext2_xattr_handler_map[name_index];131 132 if (!xattr_handler_can_list(handler, dentry))133 return NULL;134 135 return xattr_prefix(handler);136}137 138static bool139ext2_xattr_header_valid(struct ext2_xattr_header *header)140{141 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||142 header->h_blocks != cpu_to_le32(1))143 return false;144 145 return true;146}147 148static bool149ext2_xattr_entry_valid(struct ext2_xattr_entry *entry,150 char *end, size_t end_offs)151{152 struct ext2_xattr_entry *next;153 size_t size;154 155 next = EXT2_XATTR_NEXT(entry);156 if ((char *)next >= end)157 return false;158 159 if (entry->e_value_block != 0)160 return false;161 162 size = le32_to_cpu(entry->e_value_size);163 if (size > end_offs ||164 le16_to_cpu(entry->e_value_offs) + size > end_offs)165 return false;166 167 return true;168}169 170static int171ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name,172 struct ext2_xattr_entry *entry)173{174 int cmp;175 176 cmp = name_index - entry->e_name_index;177 if (!cmp)178 cmp = name_len - entry->e_name_len;179 if (!cmp)180 cmp = memcmp(name, entry->e_name, name_len);181 182 return cmp;183}184 185/*186 * ext2_xattr_get()187 *188 * Copy an extended attribute into the buffer189 * provided, or compute the buffer size required.190 * Buffer is NULL to compute the size of the buffer required.191 *192 * Returns a negative error number on failure, or the number of bytes193 * used / required on success.194 */195int196ext2_xattr_get(struct inode *inode, int name_index, const char *name,197 void *buffer, size_t buffer_size)198{199 struct buffer_head *bh = NULL;200 struct ext2_xattr_entry *entry;201 size_t name_len, size;202 char *end;203 int error, not_found;204 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);205 206 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",207 name_index, name, buffer, (long)buffer_size);208 209 if (name == NULL)210 return -EINVAL;211 name_len = strlen(name);212 if (name_len > 255)213 return -ERANGE;214 215 down_read(&EXT2_I(inode)->xattr_sem);216 error = -ENODATA;217 if (!EXT2_I(inode)->i_file_acl)218 goto cleanup;219 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);220 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);221 error = -EIO;222 if (!bh)223 goto cleanup;224 ea_bdebug(bh, "b_count=%d, refcount=%d",225 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));226 end = bh->b_data + bh->b_size;227 if (!ext2_xattr_header_valid(HDR(bh))) {228bad_block:229 ext2_error(inode->i_sb, "ext2_xattr_get",230 "inode %ld: bad block %d", inode->i_ino,231 EXT2_I(inode)->i_file_acl);232 error = -EIO;233 goto cleanup;234 }235 236 /* find named attribute */237 entry = FIRST_ENTRY(bh);238 while (!IS_LAST_ENTRY(entry)) {239 if (!ext2_xattr_entry_valid(entry, end,240 inode->i_sb->s_blocksize))241 goto bad_block;242 243 not_found = ext2_xattr_cmp_entry(name_index, name_len, name,244 entry);245 if (!not_found)246 goto found;247 if (not_found < 0)248 break;249 250 entry = EXT2_XATTR_NEXT(entry);251 }252 if (ext2_xattr_cache_insert(ea_block_cache, bh))253 ea_idebug(inode, "cache insert failed");254 error = -ENODATA;255 goto cleanup;256found:257 size = le32_to_cpu(entry->e_value_size);258 if (ext2_xattr_cache_insert(ea_block_cache, bh))259 ea_idebug(inode, "cache insert failed");260 if (buffer) {261 error = -ERANGE;262 if (size > buffer_size)263 goto cleanup;264 /* return value of attribute */265 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),266 size);267 }268 error = size;269 270cleanup:271 brelse(bh);272 up_read(&EXT2_I(inode)->xattr_sem);273 274 return error;275}276 277/*278 * ext2_xattr_list()279 *280 * Copy a list of attribute names into the buffer281 * provided, or compute the buffer size required.282 * Buffer is NULL to compute the size of the buffer required.283 *284 * Returns a negative error number on failure, or the number of bytes285 * used / required on success.286 */287static int288ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)289{290 struct inode *inode = d_inode(dentry);291 struct buffer_head *bh = NULL;292 struct ext2_xattr_entry *entry;293 char *end;294 size_t rest = buffer_size;295 int error;296 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);297 298 ea_idebug(inode, "buffer=%p, buffer_size=%ld",299 buffer, (long)buffer_size);300 301 down_read(&EXT2_I(inode)->xattr_sem);302 error = 0;303 if (!EXT2_I(inode)->i_file_acl)304 goto cleanup;305 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl);306 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);307 error = -EIO;308 if (!bh)309 goto cleanup;310 ea_bdebug(bh, "b_count=%d, refcount=%d",311 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));312 end = bh->b_data + bh->b_size;313 if (!ext2_xattr_header_valid(HDR(bh))) {314bad_block:315 ext2_error(inode->i_sb, "ext2_xattr_list",316 "inode %ld: bad block %d", inode->i_ino,317 EXT2_I(inode)->i_file_acl);318 error = -EIO;319 goto cleanup;320 }321 322 /* check the on-disk data structure */323 entry = FIRST_ENTRY(bh);324 while (!IS_LAST_ENTRY(entry)) {325 if (!ext2_xattr_entry_valid(entry, end,326 inode->i_sb->s_blocksize))327 goto bad_block;328 entry = EXT2_XATTR_NEXT(entry);329 }330 if (ext2_xattr_cache_insert(ea_block_cache, bh))331 ea_idebug(inode, "cache insert failed");332 333 /* list the attribute names */334 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry);335 entry = EXT2_XATTR_NEXT(entry)) {336 const char *prefix;337 338 prefix = ext2_xattr_prefix(entry->e_name_index, dentry);339 if (prefix) {340 size_t prefix_len = strlen(prefix);341 size_t size = prefix_len + entry->e_name_len + 1;342 343 if (buffer) {344 if (size > rest) {345 error = -ERANGE;346 goto cleanup;347 }348 memcpy(buffer, prefix, prefix_len);349 buffer += prefix_len;350 memcpy(buffer, entry->e_name, entry->e_name_len);351 buffer += entry->e_name_len;352 *buffer++ = 0;353 }354 rest -= size;355 }356 }357 error = buffer_size - rest; /* total size */358 359cleanup:360 brelse(bh);361 up_read(&EXT2_I(inode)->xattr_sem);362 363 return error;364}365 366/*367 * Inode operation listxattr()368 *369 * d_inode(dentry)->i_mutex: don't care370 */371ssize_t372ext2_listxattr(struct dentry *dentry, char *buffer, size_t size)373{374 return ext2_xattr_list(dentry, buffer, size);375}376 377/*378 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is379 * not set, set it.380 */381static void ext2_xattr_update_super_block(struct super_block *sb)382{383 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))384 return;385 386 spin_lock(&EXT2_SB(sb)->s_lock);387 ext2_update_dynamic_rev(sb);388 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);389 spin_unlock(&EXT2_SB(sb)->s_lock);390 mark_buffer_dirty(EXT2_SB(sb)->s_sbh);391}392 393/*394 * ext2_xattr_set()395 *396 * Create, replace or remove an extended attribute for this inode. Value397 * is NULL to remove an existing extended attribute, and non-NULL to398 * either replace an existing extended attribute, or create a new extended399 * attribute. The flags XATTR_REPLACE and XATTR_CREATE400 * specify that an extended attribute must exist and must not exist401 * previous to the call, respectively.402 *403 * Returns 0, or a negative error number on failure.404 */405int406ext2_xattr_set(struct inode *inode, int name_index, const char *name,407 const void *value, size_t value_len, int flags)408{409 struct super_block *sb = inode->i_sb;410 struct buffer_head *bh = NULL;411 struct ext2_xattr_header *header = NULL;412 struct ext2_xattr_entry *here = NULL, *last = NULL;413 size_t name_len, free, min_offs = sb->s_blocksize;414 int not_found = 1, error;415 char *end;416 417 /*418 * header -- Points either into bh, or to a temporarily419 * allocated buffer.420 * here -- The named entry found, or the place for inserting, within421 * the block pointed to by header.422 * last -- Points right after the last named entry within the block423 * pointed to by header.424 * min_offs -- The offset of the first value (values are aligned425 * towards the end of the block).426 * end -- Points right after the block pointed to by header.427 */428 429 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",430 name_index, name, value, (long)value_len);431 432 if (value == NULL)433 value_len = 0;434 if (name == NULL)435 return -EINVAL;436 name_len = strlen(name);437 if (name_len > 255 || value_len > sb->s_blocksize)438 return -ERANGE;439 error = dquot_initialize(inode);440 if (error)441 return error;442 down_write(&EXT2_I(inode)->xattr_sem);443 if (EXT2_I(inode)->i_file_acl) {444 /* The inode already has an extended attribute block. */445 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl);446 error = -EIO;447 if (!bh)448 goto cleanup;449 ea_bdebug(bh, "b_count=%d, refcount=%d",450 atomic_read(&(bh->b_count)),451 le32_to_cpu(HDR(bh)->h_refcount));452 header = HDR(bh);453 end = bh->b_data + bh->b_size;454 if (!ext2_xattr_header_valid(header)) {455bad_block:456 ext2_error(sb, "ext2_xattr_set",457 "inode %ld: bad block %d", inode->i_ino, 458 EXT2_I(inode)->i_file_acl);459 error = -EIO;460 goto cleanup;461 }462 /*463 * Find the named attribute. If not found, 'here' will point464 * to entry where the new attribute should be inserted to465 * maintain sorting.466 */467 last = FIRST_ENTRY(bh);468 while (!IS_LAST_ENTRY(last)) {469 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize))470 goto bad_block;471 if (last->e_value_size) {472 size_t offs = le16_to_cpu(last->e_value_offs);473 if (offs < min_offs)474 min_offs = offs;475 }476 if (not_found > 0) {477 not_found = ext2_xattr_cmp_entry(name_index,478 name_len,479 name, last);480 if (not_found <= 0)481 here = last;482 }483 last = EXT2_XATTR_NEXT(last);484 }485 if (not_found > 0)486 here = last;487 488 /* Check whether we have enough space left. */489 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32);490 } else {491 /* We will use a new extended attribute block. */492 free = sb->s_blocksize -493 sizeof(struct ext2_xattr_header) - sizeof(__u32);494 }495 496 if (not_found) {497 /* Request to remove a nonexistent attribute? */498 error = -ENODATA;499 if (flags & XATTR_REPLACE)500 goto cleanup;501 error = 0;502 if (value == NULL)503 goto cleanup;504 } else {505 /* Request to create an existing attribute? */506 error = -EEXIST;507 if (flags & XATTR_CREATE)508 goto cleanup;509 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size));510 free += EXT2_XATTR_LEN(name_len);511 }512 error = -ENOSPC;513 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len))514 goto cleanup;515 516 /* Here we know that we can set the new attribute. */517 518 if (header) {519 int offset;520 521 lock_buffer(bh);522 if (header->h_refcount == cpu_to_le32(1)) {523 __u32 hash = le32_to_cpu(header->h_hash);524 struct mb_cache_entry *oe;525 526 oe = mb_cache_entry_delete_or_get(EA_BLOCK_CACHE(inode),527 hash, bh->b_blocknr);528 if (!oe) {529 ea_bdebug(bh, "modifying in-place");530 goto update_block;531 }532 /*533 * Someone is trying to reuse the block, leave it alone534 */535 mb_cache_entry_put(EA_BLOCK_CACHE(inode), oe);536 }537 unlock_buffer(bh);538 ea_bdebug(bh, "cloning");539 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL);540 error = -ENOMEM;541 if (header == NULL)542 goto cleanup;543 header->h_refcount = cpu_to_le32(1);544 545 offset = (char *)here - bh->b_data;546 here = ENTRY((char *)header + offset);547 offset = (char *)last - bh->b_data;548 last = ENTRY((char *)header + offset);549 } else {550 /* Allocate a buffer where we construct the new block. */551 header = kzalloc(sb->s_blocksize, GFP_KERNEL);552 error = -ENOMEM;553 if (header == NULL)554 goto cleanup;555 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC);556 header->h_blocks = header->h_refcount = cpu_to_le32(1);557 last = here = ENTRY(header+1);558 }559 560update_block:561 /* Iff we are modifying the block in-place, bh is locked here. */562 563 if (not_found) {564 /* Insert the new name. */565 size_t size = EXT2_XATTR_LEN(name_len);566 size_t rest = (char *)last - (char *)here;567 memmove((char *)here + size, here, rest);568 memset(here, 0, size);569 here->e_name_index = name_index;570 here->e_name_len = name_len;571 memcpy(here->e_name, name, name_len);572 } else {573 if (here->e_value_size) {574 char *first_val = (char *)header + min_offs;575 size_t offs = le16_to_cpu(here->e_value_offs);576 char *val = (char *)header + offs;577 size_t size = EXT2_XATTR_SIZE(578 le32_to_cpu(here->e_value_size));579 580 if (size == EXT2_XATTR_SIZE(value_len)) {581 /* The old and the new value have the same582 size. Just replace. */583 here->e_value_size = cpu_to_le32(value_len);584 memset(val + size - EXT2_XATTR_PAD, 0,585 EXT2_XATTR_PAD); /* Clear pad bytes. */586 memcpy(val, value, value_len);587 goto skip_replace;588 }589 590 /* Remove the old value. */591 memmove(first_val + size, first_val, val - first_val);592 memset(first_val, 0, size);593 min_offs += size;594 595 /* Adjust all value offsets. */596 last = ENTRY(header+1);597 while (!IS_LAST_ENTRY(last)) {598 size_t o = le16_to_cpu(last->e_value_offs);599 if (o < offs)600 last->e_value_offs =601 cpu_to_le16(o + size);602 last = EXT2_XATTR_NEXT(last);603 }604 605 here->e_value_offs = 0;606 }607 if (value == NULL) {608 /* Remove the old name. */609 size_t size = EXT2_XATTR_LEN(name_len);610 last = ENTRY((char *)last - size);611 memmove(here, (char*)here + size,612 (char*)last - (char*)here);613 memset(last, 0, size);614 }615 }616 617 if (value != NULL) {618 /* Insert the new value. */619 here->e_value_size = cpu_to_le32(value_len);620 if (value_len) {621 size_t size = EXT2_XATTR_SIZE(value_len);622 char *val = (char *)header + min_offs - size;623 here->e_value_offs =624 cpu_to_le16((char *)val - (char *)header);625 memset(val + size - EXT2_XATTR_PAD, 0,626 EXT2_XATTR_PAD); /* Clear the pad bytes. */627 memcpy(val, value, value_len);628 }629 }630 631skip_replace:632 if (IS_LAST_ENTRY(ENTRY(header+1))) {633 /* This block is now empty. */634 if (bh && header == HDR(bh))635 unlock_buffer(bh); /* we were modifying in-place. */636 error = ext2_xattr_set2(inode, bh, NULL);637 } else {638 ext2_xattr_rehash(header, here);639 if (bh && header == HDR(bh))640 unlock_buffer(bh); /* we were modifying in-place. */641 error = ext2_xattr_set2(inode, bh, header);642 }643 644cleanup:645 if (!(bh && header == HDR(bh)))646 kfree(header);647 brelse(bh);648 up_write(&EXT2_I(inode)->xattr_sem);649 650 return error;651}652 653static void ext2_xattr_release_block(struct inode *inode,654 struct buffer_head *bh)655{656 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);657 658retry_ref:659 lock_buffer(bh);660 if (HDR(bh)->h_refcount == cpu_to_le32(1)) {661 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);662 struct mb_cache_entry *oe;663 664 /*665 * This must happen under buffer lock to properly666 * serialize with ext2_xattr_set() reusing the block.667 */668 oe = mb_cache_entry_delete_or_get(ea_block_cache, hash,669 bh->b_blocknr);670 if (oe) {671 /*672 * Someone is trying to reuse the block. Wait673 * and retry.674 */675 unlock_buffer(bh);676 mb_cache_entry_wait_unused(oe);677 mb_cache_entry_put(ea_block_cache, oe);678 goto retry_ref;679 }680 681 /* Free the old block. */682 ea_bdebug(bh, "freeing");683 ext2_free_blocks(inode, bh->b_blocknr, 1);684 /* We let our caller release bh, so we685 * need to duplicate the buffer before. */686 get_bh(bh);687 bforget(bh);688 unlock_buffer(bh);689 } else {690 /* Decrement the refcount only. */691 le32_add_cpu(&HDR(bh)->h_refcount, -1);692 dquot_free_block(inode, 1);693 mark_buffer_dirty(bh);694 unlock_buffer(bh);695 ea_bdebug(bh, "refcount now=%d",696 le32_to_cpu(HDR(bh)->h_refcount));697 if (IS_SYNC(inode))698 sync_dirty_buffer(bh);699 }700}701 702/*703 * Second half of ext2_xattr_set(): Update the file system.704 */705static int706ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,707 struct ext2_xattr_header *header)708{709 struct super_block *sb = inode->i_sb;710 struct buffer_head *new_bh = NULL;711 int error;712 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);713 714 if (header) {715 new_bh = ext2_xattr_cache_find(inode, header);716 if (new_bh) {717 /* We found an identical block in the cache. */718 if (new_bh == old_bh) {719 ea_bdebug(new_bh, "keeping this block");720 } else {721 /* The old block is released after updating722 the inode. */723 ea_bdebug(new_bh, "reusing block");724 725 error = dquot_alloc_block(inode, 1);726 if (error) {727 unlock_buffer(new_bh);728 goto cleanup;729 }730 le32_add_cpu(&HDR(new_bh)->h_refcount, 1);731 ea_bdebug(new_bh, "refcount now=%d",732 le32_to_cpu(HDR(new_bh)->h_refcount));733 }734 unlock_buffer(new_bh);735 } else if (old_bh && header == HDR(old_bh)) {736 /* Keep this block. No need to lock the block as we737 don't need to change the reference count. */738 new_bh = old_bh;739 get_bh(new_bh);740 ext2_xattr_cache_insert(ea_block_cache, new_bh);741 } else {742 /* We need to allocate a new block */743 ext2_fsblk_t goal = ext2_group_first_block_no(sb,744 EXT2_I(inode)->i_block_group);745 unsigned long count = 1;746 ext2_fsblk_t block = ext2_new_blocks(inode, goal,747 &count, &error,748 EXT2_ALLOC_NORESERVE);749 if (error)750 goto cleanup;751 ea_idebug(inode, "creating block %lu", block);752 753 new_bh = sb_getblk(sb, block);754 if (unlikely(!new_bh)) {755 ext2_free_blocks(inode, block, 1);756 mark_inode_dirty(inode);757 error = -ENOMEM;758 goto cleanup;759 }760 lock_buffer(new_bh);761 memcpy(new_bh->b_data, header, new_bh->b_size);762 set_buffer_uptodate(new_bh);763 unlock_buffer(new_bh);764 ext2_xattr_cache_insert(ea_block_cache, new_bh);765 766 ext2_xattr_update_super_block(sb);767 }768 mark_buffer_dirty(new_bh);769 if (IS_SYNC(inode)) {770 sync_dirty_buffer(new_bh);771 error = -EIO;772 if (buffer_req(new_bh) && !buffer_uptodate(new_bh))773 goto cleanup;774 }775 }776 777 /* Update the inode. */778 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;779 inode_set_ctime_current(inode);780 if (IS_SYNC(inode)) {781 error = sync_inode_metadata(inode, 1);782 /* In case sync failed due to ENOSPC the inode was actually783 * written (only some dirty data were not) so we just proceed784 * as if nothing happened and cleanup the unused block */785 if (error && error != -ENOSPC) {786 if (new_bh && new_bh != old_bh) {787 dquot_free_block_nodirty(inode, 1);788 mark_inode_dirty(inode);789 }790 goto cleanup;791 }792 } else793 mark_inode_dirty(inode);794 795 error = 0;796 if (old_bh && old_bh != new_bh) {797 /*798 * If there was an old block and we are no longer using it,799 * release the old block.800 */801 ext2_xattr_release_block(inode, old_bh);802 }803 804cleanup:805 brelse(new_bh);806 807 return error;808}809 810/*811 * ext2_xattr_delete_inode()812 *813 * Free extended attribute resources associated with this inode. This814 * is called immediately before an inode is freed.815 */816void817ext2_xattr_delete_inode(struct inode *inode)818{819 struct buffer_head *bh = NULL;820 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);821 822 /*823 * We are the only ones holding inode reference. The xattr_sem should824 * better be unlocked! We could as well just not acquire xattr_sem at825 * all but this makes the code more futureproof. OTOH we need trylock826 * here to avoid false-positive warning from lockdep about reclaim827 * circular dependency.828 */829 if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem)))830 return;831 if (!EXT2_I(inode)->i_file_acl)832 goto cleanup;833 834 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) {835 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",836 "inode %ld: xattr block %d is out of data blocks range",837 inode->i_ino, EXT2_I(inode)->i_file_acl);838 goto cleanup;839 }840 841 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl);842 if (!bh) {843 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",844 "inode %ld: block %d read error", inode->i_ino,845 EXT2_I(inode)->i_file_acl);846 goto cleanup;847 }848 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));849 if (!ext2_xattr_header_valid(HDR(bh))) {850 ext2_error(inode->i_sb, "ext2_xattr_delete_inode",851 "inode %ld: bad block %d", inode->i_ino,852 EXT2_I(inode)->i_file_acl);853 goto cleanup;854 }855 ext2_xattr_release_block(inode, bh);856 EXT2_I(inode)->i_file_acl = 0;857 858cleanup:859 brelse(bh);860 up_write(&EXT2_I(inode)->xattr_sem);861}862 863/*864 * ext2_xattr_cache_insert()865 *866 * Create a new entry in the extended attribute cache, and insert867 * it unless such an entry is already in the cache.868 *869 * Returns 0, or a negative error number on failure.870 */871static int872ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh)873{874 __u32 hash = le32_to_cpu(HDR(bh)->h_hash);875 int error;876 877 error = mb_cache_entry_create(cache, GFP_KERNEL, hash, bh->b_blocknr,878 true);879 if (error) {880 if (error == -EBUSY) {881 ea_bdebug(bh, "already in cache");882 error = 0;883 }884 } else885 ea_bdebug(bh, "inserting [%x]", (int)hash);886 return error;887}888 889/*890 * ext2_xattr_cmp()891 *892 * Compare two extended attribute blocks for equality.893 *894 * Returns 0 if the blocks are equal, 1 if they differ, and895 * a negative error number on errors.896 */897static int898ext2_xattr_cmp(struct ext2_xattr_header *header1,899 struct ext2_xattr_header *header2)900{901 struct ext2_xattr_entry *entry1, *entry2;902 903 entry1 = ENTRY(header1+1);904 entry2 = ENTRY(header2+1);905 while (!IS_LAST_ENTRY(entry1)) {906 if (IS_LAST_ENTRY(entry2))907 return 1;908 if (entry1->e_hash != entry2->e_hash ||909 entry1->e_name_index != entry2->e_name_index ||910 entry1->e_name_len != entry2->e_name_len ||911 entry1->e_value_size != entry2->e_value_size ||912 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))913 return 1;914 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)915 return -EIO;916 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),917 (char *)header2 + le16_to_cpu(entry2->e_value_offs),918 le32_to_cpu(entry1->e_value_size)))919 return 1;920 921 entry1 = EXT2_XATTR_NEXT(entry1);922 entry2 = EXT2_XATTR_NEXT(entry2);923 }924 if (!IS_LAST_ENTRY(entry2))925 return 1;926 return 0;927}928 929/*930 * ext2_xattr_cache_find()931 *932 * Find an identical extended attribute block.933 *934 * Returns a locked buffer head to the block found, or NULL if such935 * a block was not found or an error occurred.936 */937static struct buffer_head *938ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header)939{940 __u32 hash = le32_to_cpu(header->h_hash);941 struct mb_cache_entry *ce;942 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);943 944 if (!header->h_hash)945 return NULL; /* never share */946 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);947 948 ce = mb_cache_entry_find_first(ea_block_cache, hash);949 while (ce) {950 struct buffer_head *bh;951 952 bh = sb_bread(inode->i_sb, ce->e_value);953 if (!bh) {954 ext2_error(inode->i_sb, "ext2_xattr_cache_find",955 "inode %ld: block %ld read error",956 inode->i_ino, (unsigned long) ce->e_value);957 } else {958 lock_buffer(bh);959 if (le32_to_cpu(HDR(bh)->h_refcount) >960 EXT2_XATTR_REFCOUNT_MAX) {961 ea_idebug(inode, "block %ld refcount %d>%d",962 (unsigned long) ce->e_value,963 le32_to_cpu(HDR(bh)->h_refcount),964 EXT2_XATTR_REFCOUNT_MAX);965 } else if (!ext2_xattr_cmp(header, HDR(bh))) {966 ea_bdebug(bh, "b_count=%d",967 atomic_read(&(bh->b_count)));968 mb_cache_entry_touch(ea_block_cache, ce);969 mb_cache_entry_put(ea_block_cache, ce);970 return bh;971 }972 unlock_buffer(bh);973 brelse(bh);974 }975 ce = mb_cache_entry_find_next(ea_block_cache, ce);976 }977 return NULL;978}979 980#define NAME_HASH_SHIFT 5981#define VALUE_HASH_SHIFT 16982 983/*984 * ext2_xattr_hash_entry()985 *986 * Compute the hash of an extended attribute.987 */988static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header,989 struct ext2_xattr_entry *entry)990{991 __u32 hash = 0;992 char *name = entry->e_name;993 int n;994 995 for (n=0; n < entry->e_name_len; n++) {996 hash = (hash << NAME_HASH_SHIFT) ^997 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^998 *name++;999 }1000 1001 if (entry->e_value_block == 0 && entry->e_value_size != 0) {1002 __le32 *value = (__le32 *)((char *)header +1003 le16_to_cpu(entry->e_value_offs));1004 for (n = (le32_to_cpu(entry->e_value_size) +1005 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) {1006 hash = (hash << VALUE_HASH_SHIFT) ^1007 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^1008 le32_to_cpu(*value++);1009 }1010 }1011 entry->e_hash = cpu_to_le32(hash);1012}1013 1014#undef NAME_HASH_SHIFT1015#undef VALUE_HASH_SHIFT1016 1017#define BLOCK_HASH_SHIFT 161018 1019/*1020 * ext2_xattr_rehash()1021 *1022 * Re-compute the extended attribute hash value after an entry has changed.1023 */1024static void ext2_xattr_rehash(struct ext2_xattr_header *header,1025 struct ext2_xattr_entry *entry)1026{1027 struct ext2_xattr_entry *here;1028 __u32 hash = 0;1029 1030 ext2_xattr_hash_entry(header, entry);1031 here = ENTRY(header+1);1032 while (!IS_LAST_ENTRY(here)) {1033 if (!here->e_hash) {1034 /* Block is not shared if an entry's hash value == 0 */1035 hash = 0;1036 break;1037 }1038 hash = (hash << BLOCK_HASH_SHIFT) ^1039 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^1040 le32_to_cpu(here->e_hash);1041 here = EXT2_XATTR_NEXT(here);1042 }1043 header->h_hash = cpu_to_le32(hash);1044}1045 1046#undef BLOCK_HASH_SHIFT1047 1048#define HASH_BUCKET_BITS 101049 1050struct mb_cache *ext2_xattr_create_cache(void)1051{1052 return mb_cache_create(HASH_BUCKET_BITS);1053}1054 1055void ext2_xattr_destroy_cache(struct mb_cache *cache)1056{1057 if (cache)1058 mb_cache_destroy(cache);1059}1060