/* * linux/fs/ext2/xattr.c * * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de> * * Fix by Harrison Xing <harrison@mountainviewdata.com>. * Extended attributes for symlinks and special files added per * suggestion of Luka Renko <luka.renko@hermes.si>. * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>, * Red Hat Inc. * */ /* * Extended attributes are stored on disk blocks allocated outside of * any inode. The i_file_acl field is then made to point to this allocated * block. If all extended attributes of an inode are identical, these * inodes may share the same extended attribute block. Such situations * are automatically detected by keeping a cache of recent attribute block * numbers and hashes over the block's contents in memory. * * * Extended attribute block layout: * * +------------------+ * | header | * | entry 1 | | * | entry 2 | | growing downwards * | entry 3 | v * | four null bytes | * | . . . | * | value 1 | ^ * | value 3 | | growing upwards * | value 2 | | * +------------------+ * * The block header is followed by multiple entry descriptors. These entry * descriptors are variable in size, and aligned to EXT2_XATTR_PAD * byte boundaries. The entry descriptors are sorted by attribute name, * so that two extended attribute blocks can be compared efficiently. * * Attribute values are aligned to the end of the block, stored in * no specific order. They are also padded to EXT2_XATTR_PAD byte * boundaries. No additional gaps are left between them. * * Locking strategy * ---------------- * EXT2_I(inode)->i_file_acl is protected by EXT2_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 will change. Multiple writers to an EA block are synchronized * by the bh lock. No more than a single bh lock is held at any time * to avoid deadlocks. */ #include <linux/buffer_head.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/mbcache.h> #include <linux/quotaops.h> #include <linux/rwsem.h> #include <linux/security.h> #include "ext2.h" #include "xattr.h" #include "acl.h" #define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data)) #define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr)) #define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1) #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) #ifdef EXT2_XATTR_DEBUG # define ea_idebug(inode, f...) do { \ printk(KERN_DEBUG "inode %s:%ld: ", \ inode->i_sb->s_id, inode->i_ino); \ printk(f); \ printk("\n"); \ } while (0) # define ea_bdebug(bh, f...) do { \ printk(KERN_DEBUG "block %pg:%lu: ", \ bh->b_bdev, (unsigned long) bh->b_blocknr); \ printk(f); \ printk("\n"); \ } while (0) #else # define ea_idebug(f...) # define ea_bdebug(f...) #endif static int ext2_xattr_set2(struct inode *, struct buffer_head *, struct ext2_xattr_header *); static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *); static struct buffer_head *ext2_xattr_cache_find(struct inode *, struct ext2_xattr_header *); static void ext2_xattr_rehash(struct ext2_xattr_header *, struct ext2_xattr_entry *); static const struct xattr_handler *ext2_xattr_handler_map[] = { [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler, #ifdef CONFIG_EXT2_FS_POSIX_ACL [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler, [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler, #endif [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler, #ifdef CONFIG_EXT2_FS_SECURITY [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler, #endif }; const struct xattr_handler *ext2_xattr_handlers[] = { &ext2_xattr_user_handler, &ext2_xattr_trusted_handler, #ifdef CONFIG_EXT2_FS_POSIX_ACL &posix_acl_access_xattr_handler, &posix_acl_default_xattr_handler, #endif #ifdef CONFIG_EXT2_FS_SECURITY &ext2_xattr_security_handler, #endif NULL }; static inline const struct xattr_handler * ext2_xattr_handler(int name_index) { const struct xattr_handler *handler = NULL; if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map)) handler = ext2_xattr_handler_map[name_index]; return handler; } /* * ext2_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 ext2_xattr_get(struct inode *inode, int name_index, const char *name, void *buffer, size_t buffer_size) { struct buffer_head *bh = NULL; struct ext2_xattr_entry *entry; size_t name_len, size; char *end; int error; struct mb_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache; ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", name_index, name, buffer, (long)buffer_size); if (name == NULL) return -EINVAL; name_len = strlen(name); if (name_len > 255) return -ERANGE; down_read(&EXT2_I(inode)->xattr_sem); error = -ENODATA; if (!EXT2_I(inode)->i_file_acl) goto cleanup; ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); bh = sb_bread(inode->i_sb, EXT2_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(HDR(bh)->h_refcount)); end = bh->b_data + bh->b_size; if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || HDR(bh)->h_blocks != cpu_to_le32(1)) { bad_block: ext2_error(inode->i_sb, "ext2_xattr_get", "inode %ld: bad block %d", inode->i_ino, EXT2_I(inode)->i_file_acl); error = -EIO; goto cleanup; } /* find named attribute */ entry = FIRST_ENTRY(bh); while (!IS_LAST_ENTRY(entry)) { struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry); if ((char *)next >= end) goto bad_block; if (name_index == entry->e_name_index && name_len == entry->e_name_len && memcmp(name, entry->e_name, name_len) == 0) goto found; entry = next; } if (ext2_xattr_cache_insert(ext2_mb_cache, bh)) ea_idebug(inode, "cache insert failed"); error = -ENODATA; goto cleanup; found: /* check the buffer size */ if (entry->e_value_block != 0) goto bad_block; size = le32_to_cpu(entry->e_value_size); if (size > inode->i_sb->s_blocksize || le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize) goto bad_block; if (ext2_xattr_cache_insert(ext2_mb_cache, bh)) ea_idebug(inode, "cache insert failed"); if (buffer) { error = -ERANGE; if (size > buffer_size) goto cleanup; /* return value of attribute */ memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), size); } error = size; cleanup: brelse(bh); up_read(&EXT2_I(inode)->xattr_sem); return error; } /* * ext2_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 ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) { struct inode *inode = d_inode(dentry); struct buffer_head *bh = NULL; struct ext2_xattr_entry *entry; char *end; size_t rest = buffer_size; int error; struct mb_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache; ea_idebug(inode, "buffer=%p, buffer_size=%ld", buffer, (long)buffer_size); down_read(&EXT2_I(inode)->xattr_sem); error = 0; if (!EXT2_I(inode)->i_file_acl) goto cleanup; ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); bh = sb_bread(inode->i_sb, EXT2_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(HDR(bh)->h_refcount)); end = bh->b_data + bh->b_size; if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || HDR(bh)->h_blocks != cpu_to_le32(1)) { bad_block: ext2_error(inode->i_sb, "ext2_xattr_list", "inode %ld: bad block %d", inode->i_ino, EXT2_I(inode)->i_file_acl); error = -EIO; goto cleanup; } /* check the on-disk data structure */ entry = FIRST_ENTRY(bh); while (!IS_LAST_ENTRY(entry)) { struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry); if ((char *)next >= end) goto bad_block; entry = next; } if (ext2_xattr_cache_insert(ext2_mb_cache, bh)) ea_idebug(inode, "cache insert failed"); /* list the attribute names */ for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); entry = EXT2_XATTR_NEXT(entry)) { const struct xattr_handler *handler = ext2_xattr_handler(entry->e_name_index); if (handler && (!handler->list || handler->list(dentry))) { const char *prefix = handler->prefix ?: handler->name; size_t prefix_len = strlen(prefix); size_t size = prefix_len + entry->e_name_len + 1; if (buffer) { if (size > rest) { error = -ERANGE; goto cleanup; } memcpy(buffer, prefix, prefix_len); buffer += prefix_len; memcpy(buffer, entry->e_name, entry->e_name_len); buffer += entry->e_name_len; *buffer++ = 0; } rest -= size; } } error = buffer_size - rest; /* total size */ cleanup: brelse(bh); up_read(&EXT2_I(inode)->xattr_sem); return error; } /* * Inode operation listxattr() * * d_inode(dentry)->i_mutex: don't care */ ssize_t ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) { return ext2_xattr_list(dentry, buffer, size); } /* * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is * not set, set it. */ static void ext2_xattr_update_super_block(struct super_block *sb) { if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR)) return; spin_lock(&EXT2_SB(sb)->s_lock); EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR); spin_unlock(&EXT2_SB(sb)->s_lock); mark_buffer_dirty(EXT2_SB(sb)->s_sbh); } /* * ext2_xattr_set() * * 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 ext2_xattr_set(struct inode *inode, int name_index, const char *name, const void *value, size_t value_len, int flags) { struct super_block *sb = inode->i_sb; struct buffer_head *bh = NULL; struct ext2_xattr_header *header = NULL; struct ext2_xattr_entry *here, *last; size_t name_len, free, min_offs = sb->s_blocksize; int not_found = 1, error; char *end; /* * header -- Points either into bh, or to a temporarily * allocated buffer. * here -- The named entry found, or the place for inserting, within * the block pointed to by header. * last -- Points right after the last named entry within the block * pointed to by header. * min_offs -- The offset of the first value (values are aligned * towards the end of the block). * end -- Points right after the block pointed to by header. */ ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", name_index, name, value, (long)value_len); if (value == NULL) value_len = 0; if (name == NULL) return -EINVAL; name_len = strlen(name); if (name_len > 255 || value_len > sb->s_blocksize) return -ERANGE; down_write(&EXT2_I(inode)->xattr_sem); if (EXT2_I(inode)->i_file_acl) { /* The inode already has an extended attribute block. */ bh = sb_bread(sb, EXT2_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(HDR(bh)->h_refcount)); header = HDR(bh); end = bh->b_data + bh->b_size; if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || header->h_blocks != cpu_to_le32(1)) { bad_block: ext2_error(sb, "ext2_xattr_set", "inode %ld: bad block %d", inode->i_ino, EXT2_I(inode)->i_file_acl); error = -EIO; goto cleanup; } /* Find the named attribute. */ here = FIRST_ENTRY(bh); while (!IS_LAST_ENTRY(here)) { struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here); if ((char *)next >= end) goto bad_block; if (!here->e_value_block && here->e_value_size) { size_t offs = le16_to_cpu(here->e_value_offs); if (offs < min_offs) min_offs = offs; } not_found = name_index - here->e_name_index; if (!not_found) not_found = name_len - here->e_name_len; if (!not_found) not_found = memcmp(name, here->e_name,name_len); if (not_found <= 0) break; here = next; } last = here; /* We still need to compute min_offs and last. */ while (!IS_LAST_ENTRY(last)) { struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last); if ((char *)next >= end) goto bad_block; 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; } last = next; } /* Check whether we have enough space left. */ free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); } else { /* We will use a new extended attribute block. */ free = sb->s_blocksize - sizeof(struct ext2_xattr_header) - sizeof(__u32); here = last = NULL; /* avoid gcc uninitialized warning. */ } if (not_found) { /* Request to remove a nonexistent attribute? */ error = -ENODATA; if (flags & XATTR_REPLACE) goto cleanup; error = 0; if (value == NULL) goto cleanup; } else { /* Request to create an existing attribute? */ error = -EEXIST; if (flags & XATTR_CREATE) goto cleanup; if (!here->e_value_block && here->e_value_size) { size_t size = le32_to_cpu(here->e_value_size); if (le16_to_cpu(here->e_value_offs) + size > sb->s_blocksize || size > sb->s_blocksize) goto bad_block; free += EXT2_XATTR_SIZE(size); } free += EXT2_XATTR_LEN(name_len); } error = -ENOSPC; if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) goto cleanup; /* Here we know that we can set the new attribute. */ if (header) { /* assert(header == HDR(bh)); */ lock_buffer(bh); if (header->h_refcount == cpu_to_le32(1)) { __u32 hash = le32_to_cpu(header->h_hash); ea_bdebug(bh, "modifying in-place"); /* * This must happen under buffer lock for * ext2_xattr_set2() to reliably detect modified block */ mb_cache_entry_delete_block(EXT2_SB(sb)->s_mb_cache, hash, bh->b_blocknr); /* keep the buffer locked while modifying it. */ } else { int offset; unlock_buffer(bh); ea_bdebug(bh, "cloning"); header = kmalloc(bh->b_size, GFP_KERNEL); error = -ENOMEM; if (header == NULL) goto cleanup; memcpy(header, HDR(bh), bh->b_size); header->h_refcount = cpu_to_le32(1); offset = (char *)here - bh->b_data; here = ENTRY((char *)header + offset); offset = (char *)last - bh->b_data; last = ENTRY((char *)header + offset); } } else { /* Allocate a buffer where we construct the new block. */ header = kzalloc(sb->s_blocksize, GFP_KERNEL); error = -ENOMEM; if (header == NULL) goto cleanup; end = (char *)header + sb->s_blocksize; header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); header->h_blocks = header->h_refcount = cpu_to_le32(1); last = here = ENTRY(header+1); } /* Iff we are modifying the block in-place, bh is locked here. */ if (not_found) { /* Insert the new name. */ size_t size = EXT2_XATTR_LEN(name_len); size_t rest = (char *)last - (char *)here; memmove((char *)here + size, here, rest); memset(here, 0, size); here->e_name_index = name_index; here->e_name_len = name_len; memcpy(here->e_name, name, name_len); } else { if (!here->e_value_block && here->e_value_size) { char *first_val = (char *)header + min_offs; size_t offs = le16_to_cpu(here->e_value_offs); char *val = (char *)header + offs; size_t size = EXT2_XATTR_SIZE( le32_to_cpu(here->e_value_size)); if (size == EXT2_XATTR_SIZE(value_len)) { /* The old and the new value have the same size. Just replace. */ here->e_value_size = cpu_to_le32(value_len); memset(val + size - EXT2_XATTR_PAD, 0, EXT2_XATTR_PAD); /* Clear pad bytes. */ memcpy(val, value, value_len); goto skip_replace; } /* Remove the old value. */ memmove(first_val + size, first_val, val - first_val); memset(first_val, 0, size); here->e_value_offs = 0; min_offs += size; /* Adjust all value offsets. */ last = ENTRY(header+1); while (!IS_LAST_ENTRY(last)) { size_t o = le16_to_cpu(last->e_value_offs); if (!last->e_value_block && o < offs) last->e_value_offs = cpu_to_le16(o + size); last = EXT2_XATTR_NEXT(last); } } if (value == NULL) { /* Remove the old name. */ size_t size = EXT2_XATTR_LEN(name_len); last = ENTRY((char *)last - size); memmove(here, (char*)here + size, (char*)last - (char*)here); memset(last, 0, size); } } if (value != NULL) { /* Insert the new value. */ here->e_value_size = cpu_to_le32(value_len); if (value_len) { size_t size = EXT2_XATTR_SIZE(value_len); char *val = (char *)header + min_offs - size; here->e_value_offs = cpu_to_le16((char *)val - (char *)header); memset(val + size - EXT2_XATTR_PAD, 0, EXT2_XATTR_PAD); /* Clear the pad bytes. */ memcpy(val, value, value_len); } } skip_replace: if (IS_LAST_ENTRY(ENTRY(header+1))) { /* This block is now empty. */ if (bh && header == HDR(bh)) unlock_buffer(bh); /* we were modifying in-place. */ error = ext2_xattr_set2(inode, bh, NULL); } else { ext2_xattr_rehash(header, here); if (bh && header == HDR(bh)) unlock_buffer(bh); /* we were modifying in-place. */ error = ext2_xattr_set2(inode, bh, header); } cleanup: brelse(bh); if (!(bh && header == HDR(bh))) kfree(header); up_write(&EXT2_I(inode)->xattr_sem); return error; } /* * Second half of ext2_xattr_set(): Update the file system. */ static int ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, struct ext2_xattr_header *header) { struct super_block *sb = inode->i_sb; struct buffer_head *new_bh = NULL; int error; struct mb_cache *ext2_mb_cache = EXT2_SB(sb)->s_mb_cache; if (header) { new_bh = ext2_xattr_cache_find(inode, header); if (new_bh) { /* We found an identical block in the cache. */ if (new_bh == old_bh) { ea_bdebug(new_bh, "keeping this block"); } else { /* The old block is released after updating the inode. */ ea_bdebug(new_bh, "reusing block"); error = dquot_alloc_block(inode, 1); if (error) { unlock_buffer(new_bh); goto cleanup; } le32_add_cpu(&HDR(new_bh)->h_refcount, 1); ea_bdebug(new_bh, "refcount now=%d", le32_to_cpu(HDR(new_bh)->h_refcount)); } unlock_buffer(new_bh); } else if (old_bh && header == HDR(old_bh)) { /* Keep this block. No need to lock the block as we don't need to change the reference count. */ new_bh = old_bh; get_bh(new_bh); ext2_xattr_cache_insert(ext2_mb_cache, new_bh); } else { /* We need to allocate a new block */ ext2_fsblk_t goal = ext2_group_first_block_no(sb, EXT2_I(inode)->i_block_group); int block = ext2_new_block(inode, goal, &error); if (error) goto cleanup; ea_idebug(inode, "creating block %d", block); new_bh = sb_getblk(sb, block); if (unlikely(!new_bh)) { ext2_free_blocks(inode, block, 1); mark_inode_dirty(inode); error = -ENOMEM; goto cleanup; } lock_buffer(new_bh); memcpy(new_bh->b_data, header, new_bh->b_size); set_buffer_uptodate(new_bh); unlock_buffer(new_bh); ext2_xattr_cache_insert(ext2_mb_cache, new_bh); ext2_xattr_update_super_block(sb); } mark_buffer_dirty(new_bh); if (IS_SYNC(inode)) { sync_dirty_buffer(new_bh); error = -EIO; if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) goto cleanup; } } /* Update the inode. */ EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; inode->i_ctime = CURRENT_TIME_SEC; if (IS_SYNC(inode)) { error = sync_inode_metadata(inode, 1); /* In case sync failed due to ENOSPC the inode was actually * written (only some dirty data were not) so we just proceed * as if nothing happened and cleanup the unused block */ if (error && error != -ENOSPC) { if (new_bh && new_bh != old_bh) { dquot_free_block_nodirty(inode, 1); mark_inode_dirty(inode); } goto cleanup; } } else mark_inode_dirty(inode); error = 0; if (old_bh && old_bh != new_bh) { /* * If there was an old block and we are no longer using it, * release the old block. */ lock_buffer(old_bh); if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash); /* * This must happen under buffer lock for * ext2_xattr_set2() to reliably detect freed block */ mb_cache_entry_delete_block(ext2_mb_cache, hash, old_bh->b_blocknr); /* Free the old block. */ ea_bdebug(old_bh, "freeing"); ext2_free_blocks(inode, old_bh->b_blocknr, 1); mark_inode_dirty(inode); /* We let our caller release old_bh, so we * need to duplicate the buffer before. */ get_bh(old_bh); bforget(old_bh); } else { /* Decrement the refcount only. */ le32_add_cpu(&HDR(old_bh)->h_refcount, -1); dquot_free_block_nodirty(inode, 1); mark_inode_dirty(inode); mark_buffer_dirty(old_bh); ea_bdebug(old_bh, "refcount now=%d", le32_to_cpu(HDR(old_bh)->h_refcount)); } unlock_buffer(old_bh); } cleanup: brelse(new_bh); return error; } /* * ext2_xattr_delete_inode() * * Free extended attribute resources associated with this inode. This * is called immediately before an inode is freed. */ void ext2_xattr_delete_inode(struct inode *inode) { struct buffer_head *bh = NULL; down_write(&EXT2_I(inode)->xattr_sem); if (!EXT2_I(inode)->i_file_acl) goto cleanup; bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); if (!bh) { ext2_error(inode->i_sb, "ext2_xattr_delete_inode", "inode %ld: block %d read error", inode->i_ino, EXT2_I(inode)->i_file_acl); goto cleanup; } ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || HDR(bh)->h_blocks != cpu_to_le32(1)) { ext2_error(inode->i_sb, "ext2_xattr_delete_inode", "inode %ld: bad block %d", inode->i_ino, EXT2_I(inode)->i_file_acl); goto cleanup; } lock_buffer(bh); if (HDR(bh)->h_refcount == cpu_to_le32(1)) { __u32 hash = le32_to_cpu(HDR(bh)->h_hash); /* * This must happen under buffer lock for ext2_xattr_set2() to * reliably detect freed block */ mb_cache_entry_delete_block(EXT2_SB(inode->i_sb)->s_mb_cache, hash, bh->b_blocknr); ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); get_bh(bh); bforget(bh); unlock_buffer(bh); } else { le32_add_cpu(&HDR(bh)->h_refcount, -1); ea_bdebug(bh, "refcount now=%d", le32_to_cpu(HDR(bh)->h_refcount)); unlock_buffer(bh); mark_buffer_dirty(bh); if (IS_SYNC(inode)) sync_dirty_buffer(bh); dquot_free_block_nodirty(inode, 1); } EXT2_I(inode)->i_file_acl = 0; cleanup: brelse(bh); up_write(&EXT2_I(inode)->xattr_sem); } /* * ext2_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 int ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh) { __u32 hash = le32_to_cpu(HDR(bh)->h_hash); int error; error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, 1); if (error) { if (error == -EBUSY) { ea_bdebug(bh, "already in cache (%d cache entries)", atomic_read(&ext2_xattr_cache->c_entry_count)); error = 0; } } else ea_bdebug(bh, "inserting [%x]", (int)hash); return error; } /* * ext2_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 ext2_xattr_cmp(struct ext2_xattr_header *header1, struct ext2_xattr_header *header2) { struct ext2_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 -EIO; 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 = EXT2_XATTR_NEXT(entry1); entry2 = EXT2_XATTR_NEXT(entry2); } if (!IS_LAST_ENTRY(entry2)) return 1; return 0; } /* * ext2_xattr_cache_find() * * Find an identical extended attribute block. * * Returns a locked buffer head to the block found, or NULL if such * a block was not found or an error occurred. */ static struct buffer_head * ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) { __u32 hash = le32_to_cpu(header->h_hash); struct mb_cache_entry *ce; struct mb_cache *ext2_mb_cache = EXT2_SB(inode->i_sb)->s_mb_cache; if (!header->h_hash) return NULL; /* never share */ ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); again: ce = mb_cache_entry_find_first(ext2_mb_cache, hash); while (ce) { struct buffer_head *bh; bh = sb_bread(inode->i_sb, ce->e_block); if (!bh) { ext2_error(inode->i_sb, "ext2_xattr_cache_find", "inode %ld: block %ld read error", inode->i_ino, (unsigned long) ce->e_block); } else { lock_buffer(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)) { mb_cache_entry_put(ext2_mb_cache, ce); unlock_buffer(bh); brelse(bh); goto again; } else if (le32_to_cpu(HDR(bh)->h_refcount) > EXT2_XATTR_REFCOUNT_MAX) { ea_idebug(inode, "block %ld refcount %d>%d", (unsigned long) ce->e_block, le32_to_cpu(HDR(bh)->h_refcount), EXT2_XATTR_REFCOUNT_MAX); } else if (!ext2_xattr_cmp(header, HDR(bh))) { ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); mb_cache_entry_touch(ext2_mb_cache, ce); mb_cache_entry_put(ext2_mb_cache, ce); return bh; } unlock_buffer(bh); brelse(bh); } ce = mb_cache_entry_find_next(ext2_mb_cache, ce); } return NULL; } #define NAME_HASH_SHIFT 5 #define VALUE_HASH_SHIFT 16 /* * ext2_xattr_hash_entry() * * Compute the hash of an extended attribute. */ static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, struct ext2_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) + EXT2_XATTR_ROUND) >> EXT2_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 /* * ext2_xattr_rehash() * * Re-compute the extended attribute hash value after an entry has changed. */ static void ext2_xattr_rehash(struct ext2_xattr_header *header, struct ext2_xattr_entry *entry) { struct ext2_xattr_entry *here; __u32 hash = 0; ext2_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 = EXT2_XATTR_NEXT(here); } header->h_hash = cpu_to_le32(hash); } #undef BLOCK_HASH_SHIFT #define HASH_BUCKET_BITS 10 struct mb_cache *ext2_xattr_create_cache(void) { return mb_cache_create(HASH_BUCKET_BITS); } void ext2_xattr_destroy_cache(struct mb_cache *cache) { if (cache) mb_cache_destroy(cache); }