/* * linux/fs/ext4/xattr.c * * Copyright (C) 2001-2003 Andreas Gruenbacher, * * Fix by Harrison Xing . * Ext4 code with a lot of help from Eric Jarman . * Extended attributes for symlinks and special files added per * suggestion of Luka Renko . * xattr consolidation Copyright (c) 2004 James Morris , * Red Hat Inc. * ea-in-inode support by Alex Tomas aka bzzz * and Andreas Gruenbacher . */ /* * Extended attributes are stored directly in inodes (on file systems with * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl * field contains the block number if an inode uses an additional block. All * attributes must fit in the inode and one additional block. Blocks that * contain the identical set of attributes may be shared among several inodes. * Identical blocks are detected by keeping a cache of blocks that have * recently been accessed. * * The attributes in inodes and on blocks have a different header; the entries * are stored in the same format: * * +------------------+ * | header | * | entry 1 | | * | entry 2 | | growing downwards * | entry 3 | v * | four null bytes | * | . . . | * | value 1 | ^ * | value 3 | | growing upwards * | value 2 | | * +------------------+ * * The header is followed by multiple entry descriptors. In disk blocks, the * entry descriptors are kept sorted. In inodes, they are unsorted. The * attribute values are aligned to the end of the block in no specific order. * * Locking strategy * ---------------- * EXT4_I(inode)->i_file_acl is protected by EXT4_I(inode)->xattr_sem. * EA blocks are only changed if they are exclusive to an inode, so * holding xattr_sem also means that nothing but the EA block's reference * count can change. Multiple writers to the same block are synchronized * by the buffer lock. */ #include #include #include #include #include #include "ext4_jbd2.h" #include "ext4.h" #include "xattr.h" #include "acl.h" #ifdef EXT4_XATTR_DEBUG # define ea_idebug(inode, f...) do { \ printk(KERN_DEBUG "inode %s:%lu: ", \ inode->i_sb->s_id, inode->i_ino); \ printk(f); \ printk("\n"); \ } while (0) # define ea_bdebug(bh, f...) do { \ char b[BDEVNAME_SIZE]; \ printk(KERN_DEBUG "block %s:%lu: ", \ bdevname(bh->b_bdev, b), \ (unsigned long) bh->b_blocknr); \ printk(f); \ printk("\n"); \ } while (0) #else # define ea_idebug(inode, fmt, ...) no_printk(fmt, ##__VA_ARGS__) # define ea_bdebug(bh, fmt, ...) no_printk(fmt, ##__VA_ARGS__) #endif static void ext4_xattr_cache_insert(struct mb2_cache *, struct buffer_head *); static struct buffer_head *ext4_xattr_cache_find(struct inode *, struct ext4_xattr_header *, struct mb2_cache_entry **); static void ext4_xattr_rehash(struct ext4_xattr_header *, struct ext4_xattr_entry *); static int ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size); static const struct xattr_handler *ext4_xattr_handler_map[] = { [EXT4_XATTR_INDEX_USER] = &ext4_xattr_user_handler, #ifdef CONFIG_EXT4_FS_POSIX_ACL [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler, [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler, #endif [EXT4_XATTR_INDEX_TRUSTED] = &ext4_xattr_trusted_handler, #ifdef CONFIG_EXT4_FS_SECURITY [EXT4_XATTR_INDEX_SECURITY] = &ext4_xattr_security_handler, #endif }; const struct xattr_handler *ext4_xattr_handlers[] = { &ext4_xattr_user_handler, &ext4_xattr_trusted_handler, #ifdef CONFIG_EXT4_FS_POSIX_ACL &posix_acl_access_xattr_handler, &posix_acl_default_xattr_handler, #endif #ifdef CONFIG_EXT4_FS_SECURITY &ext4_xattr_security_handler, #endif NULL }; #define EXT4_GET_MB_CACHE(inode) (((struct ext4_sb_info *) \ inode->i_sb->s_fs_info)->s_mb_cache) static __le32 ext4_xattr_block_csum(struct inode *inode, sector_t block_nr, struct ext4_xattr_header *hdr) { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); __u32 csum; __le64 dsk_block_nr = cpu_to_le64(block_nr); __u32 dummy_csum = 0; int offset = offsetof(struct ext4_xattr_header, h_checksum); csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr, sizeof(dsk_block_nr)); csum = ext4_chksum(sbi, csum, (__u8 *)hdr, offset); csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum)); offset += sizeof(dummy_csum); csum = ext4_chksum(sbi, csum, (__u8 *)hdr + offset, EXT4_BLOCK_SIZE(inode->i_sb) - offset); return cpu_to_le32(csum); } static int ext4_xattr_block_csum_verify(struct inode *inode, sector_t block_nr, struct ext4_xattr_header *hdr) { if (ext4_has_metadata_csum(inode->i_sb) && (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr))) return 0; return 1; } static void ext4_xattr_block_csum_set(struct inode *inode, sector_t block_nr, struct ext4_xattr_header *hdr) { if (!ext4_has_metadata_csum(inode->i_sb)) return; hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr); } static inline int ext4_handle_dirty_xattr_block(handle_t *handle, struct inode *inode, struct buffer_head *bh) { ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh)); return ext4_handle_dirty_metadata(handle, inode, bh); } static inline const struct xattr_handler * ext4_xattr_handler(int name_index) { const struct xattr_handler *handler = NULL; if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map)) handler = ext4_xattr_handler_map[name_index]; return handler; } /* * Inode operation listxattr() * * d_inode(dentry)->i_mutex: don't care */ ssize_t ext4_listxattr(struct dentry *dentry, char *buffer, size_t size) { return ext4_xattr_list(dentry, buffer, size); } static int ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end, void *value_start) { struct ext4_xattr_entry *e = entry; while (!IS_LAST_ENTRY(e)) { struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e); if ((void *)next >= end) return -EFSCORRUPTED; if (strnlen(e->e_name, e->e_name_len) != e->e_name_len) return -EFSCORRUPTED; e = next; } while (!IS_LAST_ENTRY(entry)) { if (entry->e_value_size != 0 && (value_start + le16_to_cpu(entry->e_value_offs) < (void *)e + sizeof(__u32) || value_start + le16_to_cpu(entry->e_value_offs) + le32_to_cpu(entry->e_value_size) > end)) return -EFSCORRUPTED; entry = EXT4_XATTR_NEXT(entry); } return 0; } static inline int ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh) { int error; if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) || BHDR(bh)->h_blocks != cpu_to_le32(1)) return -EFSCORRUPTED; if (buffer_verified(bh)) return 0; if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh))) return -EFSBADCRC; error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size, bh->b_data); if (!error) set_buffer_verified(bh); return error; } static int __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, void *end, const char *function, unsigned int line) { struct ext4_xattr_entry *entry = IFIRST(header); int error = -EFSCORRUPTED; if (((void *) header >= end) || (header->h_magic != le32_to_cpu(EXT4_XATTR_MAGIC))) goto errout; error = ext4_xattr_check_names(entry, end, entry); errout: if (error) __ext4_error_inode(inode, function, line, 0, "corrupted in-inode xattr"); return error; } #define xattr_check_inode(inode, header, end) \ __xattr_check_inode((inode), (header), (end), __func__, __LINE__) static inline int ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size) { size_t value_size = le32_to_cpu(entry->e_value_size); if (entry->e_value_block != 0 || value_size > size || le16_to_cpu(entry->e_value_offs) + value_size > size) return -EFSCORRUPTED; return 0; } static int ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index, const char *name, size_t size, int sorted) { struct ext4_xattr_entry *entry; size_t name_len; int cmp = 1; if (name == NULL) return -EINVAL; name_len = strlen(name); entry = *pentry; for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) { cmp = name_index - entry->e_name_index; if (!cmp) cmp = name_len - entry->e_name_len; if (!cmp) cmp = memcmp(name, entry->e_name, name_len); if (cmp <= 0 && (sorted || cmp == 0)) break; } *pentry = entry; if (!cmp && ext4_xattr_check_entry(entry, size)) return -EFSCORRUPTED; return cmp ? -ENODATA : 0; } static int ext4_xattr_block_get(struct inode *inode, int name_index, const char *name, void *buffer, size_t buffer_size) { struct buffer_head *bh = NULL; struct ext4_xattr_entry *entry; size_t size; int error; struct mb2_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode); ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", name_index, name, buffer, (long)buffer_size); error = -ENODATA; if (!EXT4_I(inode)->i_file_acl) goto cleanup; ea_idebug(inode, "reading block %llu", (unsigned long long)EXT4_I(inode)->i_file_acl); bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl); if (!bh) goto cleanup; ea_bdebug(bh, "b_count=%d, refcount=%d", atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount)); if (ext4_xattr_check_block(inode, bh)) { bad_block: EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); error = -EFSCORRUPTED; goto cleanup; } ext4_xattr_cache_insert(ext4_mb_cache, bh); entry = BFIRST(bh); error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1); if (error == -EFSCORRUPTED) goto bad_block; if (error) goto cleanup; size = le32_to_cpu(entry->e_value_size); if (buffer) { error = -ERANGE; if (size > buffer_size) goto cleanup; memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), size); } error = size; cleanup: brelse(bh); return error; } int ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name, void *buffer, size_t buffer_size) { struct ext4_xattr_ibody_header *header; struct ext4_xattr_entry *entry; struct ext4_inode *raw_inode; struct ext4_iloc iloc; size_t size; void *end; int error; if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR)) return -ENODATA; error = ext4_get_inode_loc(inode, &iloc); if (error) return error; raw_inode = ext4_raw_inode(&iloc); header = IHDR(inode, raw_inode); entry = IFIRST(header); end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size; error = xattr_check_inode(inode, header, end); if (error) goto cleanup; error = ext4_xattr_find_entry(&entry, name_index, name, end - (void *)entry, 0); if (error) goto cleanup; size = le32_to_cpu(entry->e_value_size); if (buffer) { error = -ERANGE; if (size > buffer_size) goto cleanup; memcpy(buffer, (void *)IFIRST(header) + le16_to_cpu(entry->e_value_offs), size); } error = size; cleanup: brelse(iloc.bh); return error; } /* * ext4_xattr_get() * * Copy an extended attribute into the buffer * provided, or compute the buffer size required. * Buffer is NULL to compute the size of the buffer required. * * Returns a negative error number on failure, or the number of bytes * used / required on success. */ int ext4_xattr_get(struct inode *inode, int name_index, const char *name, void *buffer, size_t buffer_size) { int error; if (strlen(name) > 255) return -ERANGE; down_read(&EXT4_I(inode)->xattr_sem); error = ext4_xattr_ibody_get(inode, name_index, name, buffer, buffer_size); if (error == -ENODATA) error = ext4_xattr_block_get(inode, name_index, name, buffer, buffer_size); up_read(&EXT4_I(inode)->xattr_sem); return error; } static int ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry, char *buffer, size_t buffer_size) { size_t rest = buffer_size; for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) { const struct xattr_handler *handler = ext4_xattr_handler(entry->e_name_index); if (handler) { size_t size = handler->list(handler, dentry, buffer, rest, entry->e_name, entry->e_name_len); if (buffer) { if (size > rest) return -ERANGE; buffer += size; } rest -= size; } } return buffer_size - rest; } static int ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size) { struct inode *inode = d_inode(dentry); struct buffer_head *bh = NULL; int error; struct mb2_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode); ea_idebug(inode, "buffer=%p, buffer_size=%ld", buffer, (long)buffer_size); error = 0; if (!EXT4_I(inode)->i_file_acl) goto cleanup; ea_idebug(inode, "reading block %llu", (unsigned long long)EXT4_I(inode)->i_file_acl); bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl); error = -EIO; if (!bh) goto cleanup; ea_bdebug(bh, "b_count=%d, refcount=%d", atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount)); if (ext4_xattr_check_block(inode, bh)) { EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); error = -EFSCORRUPTED; goto cleanup; } ext4_xattr_cache_insert(ext4_mb_cache, bh); error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size); cleanup: brelse(bh); return error; } static int ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size) { struct inode *inode = d_inode(dentry); struct ext4_xattr_ibody_header *header; struct ext4_inode *raw_inode; struct ext4_iloc iloc; void *end; int error; if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR)) return 0; error = ext4_get_inode_loc(inode, &iloc); if (error) return error; raw_inode = ext4_raw_inode(&iloc); header = IHDR(inode, raw_inode); end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size; error = xattr_check_inode(inode, header, end); if (error) goto cleanup; error = ext4_xattr_list_entries(dentry, IFIRST(header), buffer, buffer_size); cleanup: brelse(iloc.bh); return error; } /* * ext4_xattr_list() * * Copy a list of attribute names into the buffer * provided, or compute the buffer size required. * Buffer is NULL to compute the size of the buffer required. * * Returns a negative error number on failure, or the number of bytes * used / required on success. */ static int ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) { int ret, ret2; down_read(&EXT4_I(d_inode(dentry))->xattr_sem); ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size); if (ret < 0) goto errout; if (buffer) { buffer += ret; buffer_size -= ret; } ret = ext4_xattr_block_list(dentry, buffer, buffer_size); if (ret < 0) goto errout; ret += ret2; errout: up_read(&EXT4_I(d_inode(dentry))->xattr_sem); return ret; } /* * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is * not set, set it. */ static void ext4_xattr_update_super_block(handle_t *handle, struct super_block *sb) { if (ext4_has_feature_xattr(sb)) return; BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access"); if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) { ext4_set_feature_xattr(sb); ext4_handle_dirty_super(handle, sb); } } /* * Release the xattr block BH: If the reference count is > 1, decrement it; * otherwise free the block. */ static void ext4_xattr_release_block(handle_t *handle, struct inode *inode, struct buffer_head *bh) { int error = 0; BUFFER_TRACE(bh, "get_write_access"); error = ext4_journal_get_write_access(handle, bh); if (error) goto out; lock_buffer(bh); if (BHDR(bh)->h_refcount == cpu_to_le32(1)) { __u32 hash = le32_to_cpu(BHDR(bh)->h_hash); ea_bdebug(bh, "refcount now=0; freeing"); /* * This must happen under buffer lock for * ext4_xattr_block_set() to reliably detect freed block */ mb2_cache_entry_delete_block(EXT4_GET_MB_CACHE(inode), hash, bh->b_blocknr); get_bh(bh); unlock_buffer(bh); ext4_free_blocks(handle, inode, bh, 0, 1, EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET); } else { le32_add_cpu(&BHDR(bh)->h_refcount, -1); /* * Beware of this ugliness: Releasing of xattr block references * from different inodes can race and so we have to protect * from a race where someone else frees the block (and releases * its journal_head) before we are done dirtying the buffer. In * nojournal mode this race is harmless and we actually cannot * call ext4_handle_dirty_xattr_block() with locked buffer as * that function can call sync_dirty_buffer() so for that case * we handle the dirtying after unlocking the buffer. */ if (ext4_handle_valid(handle)) error = ext4_handle_dirty_xattr_block(handle, inode, bh); unlock_buffer(bh); if (!ext4_handle_valid(handle)) error = ext4_handle_dirty_xattr_block(handle, inode, bh); if (IS_SYNC(inode)) ext4_handle_sync(handle); dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1)); ea_bdebug(bh, "refcount now=%d; releasing", le32_to_cpu(BHDR(bh)->h_refcount)); } out: ext4_std_error(inode->i_sb, error); return; } /* * Find the available free space for EAs. This also returns the total number of * bytes used by EA entries. */ static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last, size_t *min_offs, void *base, int *total) { for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) { if (!last->e_value_block && last->e_value_size) { size_t offs = le16_to_cpu(last->e_value_offs); if (offs < *min_offs) *min_offs = offs; } if (total) *total += EXT4_XATTR_LEN(last->e_name_len); } return (*min_offs - ((void *)last - base) - sizeof(__u32)); } static int ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s, struct inode *inode) { struct ext4_xattr_entry *last, *next; size_t free, min_offs = s->end - s->base, name_len = strlen(i->name); /* Compute min_offs and last. */ last = s->first; for (; !IS_LAST_ENTRY(last); last = next) { next = EXT4_XATTR_NEXT(last); if ((void *)next >= s->end) { EXT4_ERROR_INODE(inode, "corrupted xattr entries"); return -EFSCORRUPTED; } if (!last->e_value_block && last->e_value_size) { size_t offs = le16_to_cpu(last->e_value_offs); if (offs < min_offs) min_offs = offs; } } free = min_offs - ((void *)last - s->base) - sizeof(__u32); if (!s->not_found) { if (!s->here->e_value_block && s->here->e_value_size) { size_t size = le32_to_cpu(s->here->e_value_size); free += EXT4_XATTR_SIZE(size); } free += EXT4_XATTR_LEN(name_len); } if (i->value) { if (free < EXT4_XATTR_LEN(name_len) + EXT4_XATTR_SIZE(i->value_len)) return -ENOSPC; } if (i->value && s->not_found) { /* Insert the new name. */ size_t size = EXT4_XATTR_LEN(name_len); size_t rest = (void *)last - (void *)s->here + sizeof(__u32); memmove((void *)s->here + size, s->here, rest); memset(s->here, 0, size); s->here->e_name_index = i->name_index; s->here->e_name_len = name_len; memcpy(s->here->e_name, i->name, name_len); } else { if (!s->here->e_value_block && s->here->e_value_size) { void *first_val = s->base + min_offs; size_t offs = le16_to_cpu(s->here->e_value_offs); void *val = s->base + offs; size_t size = EXT4_XATTR_SIZE( le32_to_cpu(s->here->e_value_size)); if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) { /* The old and the new value have the same size. Just replace. */ s->here->e_value_size = cpu_to_le32(i->value_len); if (i->value == EXT4_ZERO_XATTR_VALUE) { memset(val, 0, size); } else { /* Clear pad bytes first. */ memset(val + size - EXT4_XATTR_PAD, 0, EXT4_XATTR_PAD); memcpy(val, i->value, i->value_len); } return 0; } /* Remove the old value. */ memmove(first_val + size, first_val, val - first_val); memset(first_val, 0, size); s->here->e_value_size = 0; s->here->e_value_offs = 0; min_offs += size; /* Adjust all value offsets. */ last = s->first; while (!IS_LAST_ENTRY(last)) { size_t o = le16_to_cpu(last->e_value_offs); if (!last->e_value_block && last->e_value_size && o < offs) last->e_value_offs = cpu_to_le16(o + size); last = EXT4_XATTR_NEXT(last); } } if (!i->value) { /* Remove the old name. */ size_t size = EXT4_XATTR_LEN(name_len); last = ENTRY((void *)last - size); memmove(s->here, (void *)s->here + size, (void *)last - (void *)s->here + sizeof(__u32)); memset(last, 0, size); } } if (i->value) { /* Insert the new value. */ s->here->e_value_size = cpu_to_le32(i->value_len); if (i->value_len) { size_t size = EXT4_XATTR_SIZE(i->value_len); void *val = s->base + min_offs - size; s->here->e_value_offs = cpu_to_le16(min_offs - size); if (i->value == EXT4_ZERO_XATTR_VALUE) { memset(val, 0, size); } else { /* Clear the pad bytes first. */ memset(val + size - EXT4_XATTR_PAD, 0, EXT4_XATTR_PAD); memcpy(val, i->value, i->value_len); } } } return 0; } struct ext4_xattr_block_find { struct ext4_xattr_search s; struct buffer_head *bh; }; static int ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i, struct ext4_xattr_block_find *bs) { struct super_block *sb = inode->i_sb; int error; ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", i->name_index, i->name, i->value, (long)i->value_len); if (EXT4_I(inode)->i_file_acl) { /* The inode already has an extended attribute block. */ bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl); error = -EIO; if (!bs->bh) goto cleanup; ea_bdebug(bs->bh, "b_count=%d, refcount=%d", atomic_read(&(bs->bh->b_count)), le32_to_cpu(BHDR(bs->bh)->h_refcount)); if (ext4_xattr_check_block(inode, bs->bh)) { EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); error = -EFSCORRUPTED; goto cleanup; } /* Find the named attribute. */ bs->s.base = BHDR(bs->bh); bs->s.first = BFIRST(bs->bh); bs->s.end = bs->bh->b_data + bs->bh->b_size; bs->s.here = bs->s.first; error = ext4_xattr_find_entry(&bs->s.here, i->name_index, i->name, bs->bh->b_size, 1); if (error && error != -ENODATA) goto cleanup; bs->s.not_found = error; } error = 0; cleanup: return error; } static int ext4_xattr_block_set(handle_t *handle, struct inode *inode, struct ext4_xattr_info *i, struct ext4_xattr_block_find *bs) { struct super_block *sb = inode->i_sb; struct buffer_head *new_bh = NULL; struct ext4_xattr_search *s = &bs->s; struct mb2_cache_entry *ce = NULL; int error = 0; struct mb2_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode); #define header(x) ((struct ext4_xattr_header *)(x)) if (i->value && i->value_len > sb->s_blocksize) return -ENOSPC; if (s->base) { BUFFER_TRACE(bs->bh, "get_write_access"); error = ext4_journal_get_write_access(handle, bs->bh); if (error) goto cleanup; lock_buffer(bs->bh); if (header(s->base)->h_refcount == cpu_to_le32(1)) { __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash); /* * This must happen under buffer lock for * ext4_xattr_block_set() to reliably detect modified * block */ mb2_cache_entry_delete_block(ext4_mb_cache, hash, bs->bh->b_blocknr); ea_bdebug(bs->bh, "modifying in-place"); error = ext4_xattr_set_entry(i, s, inode); if (!error) { if (!IS_LAST_ENTRY(s->first)) ext4_xattr_rehash(header(s->base), s->here); } unlock_buffer(bs->bh); if (error == -EFSCORRUPTED) goto bad_block; if (!error) error = ext4_handle_dirty_xattr_block(handle, inode, bs->bh); if (error) goto cleanup; goto inserted; } else { int offset = (char *)s->here - bs->bh->b_data; unlock_buffer(bs->bh); ea_bdebug(bs->bh, "cloning"); s->base = kmalloc(bs->bh->b_size, GFP_NOFS); error = -ENOMEM; if (s->base == NULL) goto cleanup; memcpy(s->base, BHDR(bs->bh), bs->bh->b_size); s->first = ENTRY(header(s->base)+1); header(s->base)->h_refcount = cpu_to_le32(1); s->here = ENTRY(s->base + offset); s->end = s->base + bs->bh->b_size; } } else { /* Allocate a buffer where we construct the new block. */ s->base = kzalloc(sb->s_blocksize, GFP_NOFS); /* assert(header == s->base) */ error = -ENOMEM; if (s->base == NULL) goto cleanup; header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC); header(s->base)->h_blocks = cpu_to_le32(1); header(s->base)->h_refcount = cpu_to_le32(1); s->first = ENTRY(header(s->base)+1); s->here = ENTRY(header(s->base)+1); s->end = s->base + sb->s_blocksize; } error = ext4_xattr_set_entry(i, s, inode); if (error == -EFSCORRUPTED) goto bad_block; if (error) goto cleanup; if (!IS_LAST_ENTRY(s->first)) ext4_xattr_rehash(header(s->base), s->here); inserted: if (!IS_LAST_ENTRY(s->first)) { new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce); if (new_bh) { /* We found an identical block in the cache. */ if (new_bh == bs->bh) ea_bdebug(new_bh, "keeping"); else { /* The old block is released after updating the inode. */ error = dquot_alloc_block(inode, EXT4_C2B(EXT4_SB(sb), 1)); if (error) goto cleanup; BUFFER_TRACE(new_bh, "get_write_access"); error = ext4_journal_get_write_access(handle, new_bh); if (error) goto cleanup_dquot; lock_buffer(new_bh); /* * We have to be careful about races with * freeing or rehashing of xattr block. Once we * hold buffer lock xattr block's state is * stable so we can check whether the block got * freed / rehashed or not. Since we unhash * mbcache entry under buffer lock when freeing * / rehashing xattr block, checking whether * entry is still hashed is reliable. */ if (hlist_bl_unhashed(&ce->e_hash_list)) { /* * Undo everything and check mbcache * again. */ unlock_buffer(new_bh); dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1)); brelse(new_bh); mb2_cache_entry_put(ext4_mb_cache, ce); ce = NULL; new_bh = NULL; goto inserted; } le32_add_cpu(&BHDR(new_bh)->h_refcount, 1); ea_bdebug(new_bh, "reusing; refcount now=%d", le32_to_cpu(BHDR(new_bh)->h_refcount)); unlock_buffer(new_bh); error = ext4_handle_dirty_xattr_block(handle, inode, new_bh); if (error) goto cleanup_dquot; } mb2_cache_entry_touch(ext4_mb_cache, ce); mb2_cache_entry_put(ext4_mb_cache, ce); ce = NULL; } else if (bs->bh && s->base == bs->bh->b_data) { /* We were modifying this block in-place. */ ea_bdebug(bs->bh, "keeping this block"); ext4_xattr_cache_insert(ext4_mb_cache, bs->bh); new_bh = bs->bh; get_bh(new_bh); } else { /* We need to allocate a new block */ ext4_fsblk_t goal, block; goal = ext4_group_first_block_no(sb, EXT4_I(inode)->i_block_group); /* non-extent files can't have physical blocks past 2^32 */ if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) goal = goal & EXT4_MAX_BLOCK_FILE_PHYS; block = ext4_new_meta_blocks(handle, inode, goal, 0, NULL, &error); if (error) goto cleanup; if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS); ea_idebug(inode, "creating block %llu", (unsigned long long)block); new_bh = sb_getblk(sb, block); if (unlikely(!new_bh)) { error = -ENOMEM; getblk_failed: ext4_free_blocks(handle, inode, NULL, block, 1, EXT4_FREE_BLOCKS_METADATA); goto cleanup; } lock_buffer(new_bh); error = ext4_journal_get_create_access(handle, new_bh); if (error) { unlock_buffer(new_bh); error = -EIO; goto getblk_failed; } memcpy(new_bh->b_data, s->base, new_bh->b_size); set_buffer_uptodate(new_bh); unlock_buffer(new_bh); ext4_xattr_cache_insert(ext4_mb_cache, new_bh); error = ext4_handle_dirty_xattr_block(handle, inode, new_bh); if (error) goto cleanup; } } /* Update the inode. */ EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; /* Drop the previous xattr block. */ if (bs->bh && bs->bh != new_bh) ext4_xattr_release_block(handle, inode, bs->bh); error = 0; cleanup: if (ce) mb2_cache_entry_put(ext4_mb_cache, ce); brelse(new_bh); if (!(bs->bh && s->base == bs->bh->b_data)) kfree(s->base); return error; cleanup_dquot: dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1)); goto cleanup; bad_block: EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); goto cleanup; #undef header } int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i, struct ext4_xattr_ibody_find *is) { struct ext4_xattr_ibody_header *header; struct ext4_inode *raw_inode; int error; if (EXT4_I(inode)->i_extra_isize == 0) return 0; raw_inode = ext4_raw_inode(&is->iloc); header = IHDR(inode, raw_inode); is->s.base = is->s.first = IFIRST(header); is->s.here = is->s.first; is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size; if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) { error = xattr_check_inode(inode, header, is->s.end); if (error) return error; /* Find the named attribute. */ error = ext4_xattr_find_entry(&is->s.here, i->name_index, i->name, is->s.end - (void *)is->s.base, 0); if (error && error != -ENODATA) return error; is->s.not_found = error; } return 0; } int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode, struct ext4_xattr_info *i, struct ext4_xattr_ibody_find *is) { struct ext4_xattr_ibody_header *header; struct ext4_xattr_search *s = &is->s; int error; if (EXT4_I(inode)->i_extra_isize == 0) return -ENOSPC; error = ext4_xattr_set_entry(i, s, inode); if (error) return error; header = IHDR(inode, ext4_raw_inode(&is->iloc)); if (!IS_LAST_ENTRY(s->first)) { header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC); ext4_set_inode_state(inode, EXT4_STATE_XATTR); } else { header->h_magic = cpu_to_le32(0); ext4_clear_inode_state(inode, EXT4_STATE_XATTR); } return 0; } static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode, struct ext4_xattr_info *i, struct ext4_xattr_ibody_find *is) { struct ext4_xattr_ibody_header *header; struct ext4_xattr_search *s = &is->s; int error; if (EXT4_I(inode)->i_extra_isize == 0) return -ENOSPC; error = ext4_xattr_set_entry(i, s, inode); if (error) return error; header = IHDR(inode, ext4_raw_inode(&is->iloc)); if (!IS_LAST_ENTRY(s->first)) { header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC); ext4_set_inode_state(inode, EXT4_STATE_XATTR); } else { header->h_magic = cpu_to_le32(0); ext4_clear_inode_state(inode, EXT4_STATE_XATTR); } return 0; } /* * ext4_xattr_set_handle() * * Create, replace or remove an extended attribute for this inode. Value * is NULL to remove an existing extended attribute, and non-NULL to * either replace an existing extended attribute, or create a new extended * attribute. The flags XATTR_REPLACE and XATTR_CREATE * specify that an extended attribute must exist and must not exist * previous to the call, respectively. * * Returns 0, or a negative error number on failure. */ int ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index, const char *name, const void *value, size_t value_len, int flags) { struct ext4_xattr_info i = { .name_index = name_index, .name = name, .value = value, .value_len = value_len, }; struct ext4_xattr_ibody_find is = { .s = { .not_found = -ENODATA, }, }; struct ext4_xattr_block_find bs = { .s = { .not_found = -ENODATA, }, }; int no_expand; int error; if (!name) return -EINVAL; if (strlen(name) > 255) return -ERANGE; ext4_write_lock_xattr(inode, &no_expand); error = ext4_reserve_inode_write(handle, inode, &is.iloc); if (error) goto cleanup; if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) { struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc); memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size); ext4_clear_inode_state(inode, EXT4_STATE_NEW); } error = ext4_xattr_ibody_find(inode, &i, &is); if (error) goto cleanup; if (is.s.not_found) error = ext4_xattr_block_find(inode, &i, &bs); if (error) goto cleanup; if (is.s.not_found && bs.s.not_found) { error = -ENODATA; if (flags & XATTR_REPLACE) goto cleanup; error = 0; if (!value) goto cleanup; } else { error = -EEXIST; if (flags & XATTR_CREATE) goto cleanup; } if (!value) { if (!is.s.not_found) error = ext4_xattr_ibody_set(handle, inode, &i, &is); else if (!bs.s.not_found) error = ext4_xattr_block_set(handle, inode, &i, &bs); } else { error = ext4_xattr_ibody_set(handle, inode, &i, &is); if (!error && !bs.s.not_found) { i.value = NULL; error = ext4_xattr_block_set(handle, inode, &i, &bs); } else if (error == -ENOSPC) { if (EXT4_I(inode)->i_file_acl && !bs.s.base) { brelse(bs.bh); bs.bh = NULL; error = ext4_xattr_block_find(inode, &i, &bs); if (error) goto cleanup; } error = ext4_xattr_block_set(handle, inode, &i, &bs); if (error) goto cleanup; if (!is.s.not_found) { i.value = NULL; error = ext4_xattr_ibody_set(handle, inode, &i, &is); } } } if (!error) { ext4_xattr_update_super_block(handle, inode->i_sb); inode->i_ctime = ext4_current_time(inode); if (!value) no_expand = 0; error = ext4_mark_iloc_dirty(handle, inode, &is.iloc); /* * The bh is consumed by ext4_mark_iloc_dirty, even with * error != 0. */ is.iloc.bh = NULL; if (IS_SYNC(inode)) ext4_handle_sync(handle); } cleanup: brelse(is.iloc.bh); brelse(bs.bh); ext4_write_unlock_xattr(inode, &no_expand); return error; } /* * ext4_xattr_set() * * Like ext4_xattr_set_handle, but start from an inode. This extended * attribute modification is a filesystem transaction by itself. * * Returns 0, or a negative error number on failure. */ int ext4_xattr_set(struct inode *inode, int name_index, const char *name, const void *value, size_t value_len, int flags) { handle_t *handle; int error, retries = 0; int credits = ext4_jbd2_credits_xattr(inode); retry: handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits); if (IS_ERR(handle)) { error = PTR_ERR(handle); } else { int error2; error = ext4_xattr_set_handle(handle, inode, name_index, name, value, value_len, flags); error2 = ext4_journal_stop(handle); if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) goto retry; if (error == 0) error = error2; } return error; } /* * Shift the EA entries in the inode to create space for the increased * i_extra_isize. */ static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry, int value_offs_shift, void *to, void *from, size_t n, int blocksize) { struct ext4_xattr_entry *last = entry; int new_offs; /* Adjust the value offsets of the entries */ for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) { if (!last->e_value_block && last->e_value_size) { new_offs = le16_to_cpu(last->e_value_offs) + value_offs_shift; BUG_ON(new_offs + le32_to_cpu(last->e_value_size) > blocksize); last->e_value_offs = cpu_to_le16(new_offs); } } /* Shift the entries by n bytes */ memmove(to, from, n); } /* * Expand an inode by new_extra_isize bytes when EAs are present. * Returns 0 on success or negative error number on failure. */ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize, struct ext4_inode *raw_inode, handle_t *handle) { struct ext4_xattr_ibody_header *header; struct ext4_xattr_entry *entry, *last, *first; struct buffer_head *bh = NULL; struct ext4_xattr_ibody_find *is = NULL; struct ext4_xattr_block_find *bs = NULL; char *buffer = NULL, *b_entry_name = NULL; size_t min_offs, free; int total_ino; void *base, *start, *end; int error = 0, tried_min_extra_isize = 0; int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize); int isize_diff; /* How much do we need to grow i_extra_isize */ int no_expand; if (ext4_write_trylock_xattr(inode, &no_expand) == 0) return 0; retry: isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize; if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) goto out; header = IHDR(inode, raw_inode); entry = IFIRST(header); /* * Check if enough free space is available in the inode to shift the * entries ahead by new_extra_isize. */ base = start = entry; end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size; min_offs = end - base; last = entry; total_ino = sizeof(struct ext4_xattr_ibody_header); error = xattr_check_inode(inode, header, end); if (error) goto cleanup; free = ext4_xattr_free_space(last, &min_offs, base, &total_ino); if (free >= isize_diff) { entry = IFIRST(header); ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize - new_extra_isize, (void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize, (void *)header, total_ino, inode->i_sb->s_blocksize); EXT4_I(inode)->i_extra_isize = new_extra_isize; goto out; } /* * Enough free space isn't available in the inode, check if * EA block can hold new_extra_isize bytes. */ if (EXT4_I(inode)->i_file_acl) { bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl); error = -EIO; if (!bh) goto cleanup; if (ext4_xattr_check_block(inode, bh)) { EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); error = -EFSCORRUPTED; goto cleanup; } base = BHDR(bh); first = BFIRST(bh); end = bh->b_data + bh->b_size; min_offs = end - base; free = ext4_xattr_free_space(first, &min_offs, base, NULL); if (free < isize_diff) { if (!tried_min_extra_isize && s_min_extra_isize) { tried_min_extra_isize++; new_extra_isize = s_min_extra_isize; brelse(bh); goto retry; } error = -1; goto cleanup; } } else { free = inode->i_sb->s_blocksize; } while (isize_diff > 0) { size_t offs, size, entry_size; struct ext4_xattr_entry *small_entry = NULL; struct ext4_xattr_info i = { .value = NULL, .value_len = 0, }; unsigned int total_size; /* EA entry size + value size */ unsigned int shift_bytes; /* No. of bytes to shift EAs by? */ unsigned int min_total_size = ~0U; is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS); bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS); if (!is || !bs) { error = -ENOMEM; goto cleanup; } is->s.not_found = -ENODATA; bs->s.not_found = -ENODATA; is->iloc.bh = NULL; bs->bh = NULL; last = IFIRST(header); /* Find the entry best suited to be pushed into EA block */ entry = NULL; for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) { /* never move system.data out of the inode */ if ((last->e_name_len == 4) && (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) && !memcmp(last->e_name, "data", 4)) continue; total_size = EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) + EXT4_XATTR_LEN(last->e_name_len); if (total_size <= free && total_size < min_total_size) { if (total_size < isize_diff) { small_entry = last; } else { entry = last; min_total_size = total_size; } } } if (entry == NULL) { if (small_entry) { entry = small_entry; } else { if (!tried_min_extra_isize && s_min_extra_isize) { tried_min_extra_isize++; new_extra_isize = s_min_extra_isize; kfree(is); is = NULL; kfree(bs); bs = NULL; brelse(bh); goto retry; } error = -1; goto cleanup; } } offs = le16_to_cpu(entry->e_value_offs); size = le32_to_cpu(entry->e_value_size); entry_size = EXT4_XATTR_LEN(entry->e_name_len); i.name_index = entry->e_name_index, buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS); b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS); if (!buffer || !b_entry_name) { error = -ENOMEM; goto cleanup; } /* Save the entry name and the entry value */ memcpy(buffer, (void *)IFIRST(header) + offs, EXT4_XATTR_SIZE(size)); memcpy(b_entry_name, entry->e_name, entry->e_name_len); b_entry_name[entry->e_name_len] = '\0'; i.name = b_entry_name; error = ext4_get_inode_loc(inode, &is->iloc); if (error) goto cleanup; error = ext4_xattr_ibody_find(inode, &i, is); if (error) goto cleanup; /* Remove the chosen entry from the inode */ error = ext4_xattr_ibody_set(handle, inode, &i, is); if (error) goto cleanup; total_ino -= entry_size; entry = IFIRST(header); if (entry_size + EXT4_XATTR_SIZE(size) >= isize_diff) shift_bytes = isize_diff; else shift_bytes = entry_size + EXT4_XATTR_SIZE(size); /* Adjust the offsets and shift the remaining entries ahead */ ext4_xattr_shift_entries(entry, -shift_bytes, (void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE + EXT4_I(inode)->i_extra_isize + shift_bytes, (void *)header, total_ino, inode->i_sb->s_blocksize); isize_diff -= shift_bytes; EXT4_I(inode)->i_extra_isize += shift_bytes; header = IHDR(inode, raw_inode); i.name = b_entry_name; i.value = buffer; i.value_len = size; error = ext4_xattr_block_find(inode, &i, bs); if (error) goto cleanup; /* Add entry which was removed from the inode into the block */ error = ext4_xattr_block_set(handle, inode, &i, bs); if (error) goto cleanup; kfree(b_entry_name); kfree(buffer); b_entry_name = NULL; buffer = NULL; brelse(is->iloc.bh); kfree(is); kfree(bs); } brelse(bh); out: ext4_write_unlock_xattr(inode, &no_expand); return 0; cleanup: kfree(b_entry_name); kfree(buffer); if (is) brelse(is->iloc.bh); if (bs) brelse(bs->bh); kfree(is); kfree(bs); brelse(bh); /* * Inode size expansion failed; don't try again */ no_expand = 1; ext4_write_unlock_xattr(inode, &no_expand); return error; } /* * ext4_xattr_delete_inode() * * Free extended attribute resources associated with this inode. This * is called immediately before an inode is freed. We have exclusive * access to the inode. */ void ext4_xattr_delete_inode(handle_t *handle, struct inode *inode) { struct buffer_head *bh = NULL; if (!EXT4_I(inode)->i_file_acl) goto cleanup; bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl); if (!bh) { EXT4_ERROR_INODE(inode, "block %llu read error", EXT4_I(inode)->i_file_acl); goto cleanup; } if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) || BHDR(bh)->h_blocks != cpu_to_le32(1)) { EXT4_ERROR_INODE(inode, "bad block %llu", EXT4_I(inode)->i_file_acl); goto cleanup; } ext4_xattr_release_block(handle, inode, bh); EXT4_I(inode)->i_file_acl = 0; cleanup: brelse(bh); } /* * ext4_xattr_cache_insert() * * Create a new entry in the extended attribute cache, and insert * it unless such an entry is already in the cache. * * Returns 0, or a negative error number on failure. */ static void ext4_xattr_cache_insert(struct mb2_cache *ext4_mb_cache, struct buffer_head *bh) { __u32 hash = le32_to_cpu(BHDR(bh)->h_hash); int error; error = mb2_cache_entry_create(ext4_mb_cache, GFP_NOFS, hash, bh->b_blocknr); if (error) { if (error == -EBUSY) ea_bdebug(bh, "already in cache"); } else ea_bdebug(bh, "inserting [%x]", (int)hash); } /* * ext4_xattr_cmp() * * Compare two extended attribute blocks for equality. * * Returns 0 if the blocks are equal, 1 if they differ, and * a negative error number on errors. */ static int ext4_xattr_cmp(struct ext4_xattr_header *header1, struct ext4_xattr_header *header2) { struct ext4_xattr_entry *entry1, *entry2; entry1 = ENTRY(header1+1); entry2 = ENTRY(header2+1); while (!IS_LAST_ENTRY(entry1)) { if (IS_LAST_ENTRY(entry2)) return 1; if (entry1->e_hash != entry2->e_hash || entry1->e_name_index != entry2->e_name_index || entry1->e_name_len != entry2->e_name_len || entry1->e_value_size != entry2->e_value_size || memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) return 1; if (entry1->e_value_block != 0 || entry2->e_value_block != 0) return -EFSCORRUPTED; if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), (char *)header2 + le16_to_cpu(entry2->e_value_offs), le32_to_cpu(entry1->e_value_size))) return 1; entry1 = EXT4_XATTR_NEXT(entry1); entry2 = EXT4_XATTR_NEXT(entry2); } if (!IS_LAST_ENTRY(entry2)) return 1; return 0; } /* * ext4_xattr_cache_find() * * Find an identical extended attribute block. * * Returns a pointer to the block found, or NULL if such a block was * not found or an error occurred. */ static struct buffer_head * ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header, struct mb2_cache_entry **pce) { __u32 hash = le32_to_cpu(header->h_hash); struct mb2_cache_entry *ce; struct mb2_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode); if (!header->h_hash) return NULL; /* never share */ ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); ce = mb2_cache_entry_find_first(ext4_mb_cache, hash); while (ce) { struct buffer_head *bh; bh = sb_bread(inode->i_sb, ce->e_block); if (!bh) { EXT4_ERROR_INODE(inode, "block %lu read error", (unsigned long) ce->e_block); } else if (le32_to_cpu(BHDR(bh)->h_refcount) >= EXT4_XATTR_REFCOUNT_MAX) { ea_idebug(inode, "block %lu refcount %d>=%d", (unsigned long) ce->e_block, le32_to_cpu(BHDR(bh)->h_refcount), EXT4_XATTR_REFCOUNT_MAX); } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) { *pce = ce; return bh; } brelse(bh); ce = mb2_cache_entry_find_next(ext4_mb_cache, ce); } return NULL; } #define NAME_HASH_SHIFT 5 #define VALUE_HASH_SHIFT 16 /* * ext4_xattr_hash_entry() * * Compute the hash of an extended attribute. */ static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header, struct ext4_xattr_entry *entry) { __u32 hash = 0; char *name = entry->e_name; int n; for (n = 0; n < entry->e_name_len; n++) { hash = (hash << NAME_HASH_SHIFT) ^ (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ *name++; } if (entry->e_value_block == 0 && entry->e_value_size != 0) { __le32 *value = (__le32 *)((char *)header + le16_to_cpu(entry->e_value_offs)); for (n = (le32_to_cpu(entry->e_value_size) + EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) { hash = (hash << VALUE_HASH_SHIFT) ^ (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ le32_to_cpu(*value++); } } entry->e_hash = cpu_to_le32(hash); } #undef NAME_HASH_SHIFT #undef VALUE_HASH_SHIFT #define BLOCK_HASH_SHIFT 16 /* * ext4_xattr_rehash() * * Re-compute the extended attribute hash value after an entry has changed. */ static void ext4_xattr_rehash(struct ext4_xattr_header *header, struct ext4_xattr_entry *entry) { struct ext4_xattr_entry *here; __u32 hash = 0; ext4_xattr_hash_entry(header, entry); here = ENTRY(header+1); while (!IS_LAST_ENTRY(here)) { if (!here->e_hash) { /* Block is not shared if an entry's hash value == 0 */ hash = 0; break; } hash = (hash << BLOCK_HASH_SHIFT) ^ (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ le32_to_cpu(here->e_hash); here = EXT4_XATTR_NEXT(here); } header->h_hash = cpu_to_le32(hash); } #undef BLOCK_HASH_SHIFT #define HASH_BUCKET_BITS 10 struct mb2_cache * ext4_xattr_create_cache(void) { return mb2_cache_create(HASH_BUCKET_BITS); } void ext4_xattr_destroy_cache(struct mb2_cache *cache) { if (cache) mb2_cache_destroy(cache); }