Directories are indexed in two ways. The first index is based on a
hash of the file name (crc32c right now) and the second index is based
on a per-directory sequence number.
The first index gives us fast lookups of file names, and the second index
gives us a stable index for readdir/telldir and NFS. Since the
second index is roughly similar to inode order on disk, it allows
readdir to return things in a good order for reading the files returned.
xattrs are indexed by a hash of the name in a very similar fashion to the
directories, and so their helpers are implemented here as well.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
new file mode 100644
index 0000000..926a0b2
--- /dev/null
+++ b/fs/btrfs/dir-item.c
@@ -0,0 +1,386 @@
+/*
+ * Copyright (C) 2007 Oracle. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include "ctree.h"
+#include "disk-io.h"
+#include "hash.h"
+#include "transaction.h"
+
+/*
+ * insert a name into a directory, doing overflow properly if there is a hash
+ * collision. data_size indicates how big the item inserted should be. On
+ * success a struct btrfs_dir_item pointer is returned, otherwise it is
+ * an ERR_PTR.
+ *
+ * The name is not copied into the dir item, you have to do that yourself.
+ */
+static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
+ *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ struct btrfs_key *cpu_key,
+ u32 data_size,
+ const char *name,
+ int name_len)
+{
+ int ret;
+ char *ptr;
+ struct btrfs_item *item;
+ struct extent_buffer *leaf;
+
+ ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
+ if (ret == -EEXIST) {
+ struct btrfs_dir_item *di;
+ di = btrfs_match_dir_item_name(root, path, name, name_len);
+ if (di)
+ return ERR_PTR(-EEXIST);
+ ret = btrfs_extend_item(trans, root, path, data_size);
+ WARN_ON(ret > 0);
+ }
+ if (ret < 0)
+ return ERR_PTR(ret);
+ WARN_ON(ret > 0);
+ leaf = path->nodes[0];
+ item = btrfs_item_nr(leaf, path->slots[0]);
+ ptr = btrfs_item_ptr(leaf, path->slots[0], char);
+ BUG_ON(data_size > btrfs_item_size(leaf, item));
+ ptr += btrfs_item_size(leaf, item) - data_size;
+ return (struct btrfs_dir_item *)ptr;
+}
+
+/*
+ * xattrs work a lot like directories, this inserts an xattr item
+ * into the tree
+ */
+int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, const char *name,
+ u16 name_len, const void *data, u16 data_len,
+ u64 dir)
+{
+ int ret = 0;
+ struct btrfs_path *path;
+ struct btrfs_dir_item *dir_item;
+ unsigned long name_ptr, data_ptr;
+ struct btrfs_key key, location;
+ struct btrfs_disk_key disk_key;
+ struct extent_buffer *leaf;
+ u32 data_size;
+
+ key.objectid = dir;
+ btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
+ key.offset = btrfs_name_hash(name, name_len);
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ if (name_len + data_len + sizeof(struct btrfs_dir_item) >
+ BTRFS_LEAF_DATA_SIZE(root) - sizeof(struct btrfs_item))
+ return -ENOSPC;
+
+ data_size = sizeof(*dir_item) + name_len + data_len;
+ dir_item = insert_with_overflow(trans, root, path, &key, data_size,
+ name, name_len);
+ /*
+ * FIXME: at some point we should handle xattr's that are larger than
+ * what we can fit in our leaf. We set location to NULL b/c we arent
+ * pointing at anything else, that will change if we store the xattr
+ * data in a separate inode.
+ */
+ BUG_ON(IS_ERR(dir_item));
+ memset(&location, 0, sizeof(location));
+
+ leaf = path->nodes[0];
+ btrfs_cpu_key_to_disk(&disk_key, &location);
+ btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
+ btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
+ btrfs_set_dir_name_len(leaf, dir_item, name_len);
+ btrfs_set_dir_transid(leaf, dir_item, trans->transid);
+ btrfs_set_dir_data_len(leaf, dir_item, data_len);
+ name_ptr = (unsigned long)(dir_item + 1);
+ data_ptr = (unsigned long)((char *)name_ptr + name_len);
+
+ write_extent_buffer(leaf, name, name_ptr, name_len);
+ write_extent_buffer(leaf, data, data_ptr, data_len);
+ btrfs_mark_buffer_dirty(path->nodes[0]);
+
+ btrfs_free_path(path);
+ return ret;
+}
+
+/*
+ * insert a directory item in the tree, doing all the magic for
+ * both indexes. 'dir' indicates which objectid to insert it into,
+ * 'location' is the key to stuff into the directory item, 'type' is the
+ * type of the inode we're pointing to, and 'index' is the sequence number
+ * to use for the second index (if one is created).
+ */
+int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
+ *root, const char *name, int name_len, u64 dir,
+ struct btrfs_key *location, u8 type, u64 index)
+{
+ int ret = 0;
+ int ret2 = 0;
+ struct btrfs_path *path;
+ struct btrfs_dir_item *dir_item;
+ struct extent_buffer *leaf;
+ unsigned long name_ptr;
+ struct btrfs_key key;
+ struct btrfs_disk_key disk_key;
+ u32 data_size;
+
+ key.objectid = dir;
+ btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
+ key.offset = btrfs_name_hash(name, name_len);
+ path = btrfs_alloc_path();
+ data_size = sizeof(*dir_item) + name_len;
+ dir_item = insert_with_overflow(trans, root, path, &key, data_size,
+ name, name_len);
+ if (IS_ERR(dir_item)) {
+ ret = PTR_ERR(dir_item);
+ if (ret == -EEXIST)
+ goto second_insert;
+ goto out;
+ }
+
+ leaf = path->nodes[0];
+ btrfs_cpu_key_to_disk(&disk_key, location);
+ btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
+ btrfs_set_dir_type(leaf, dir_item, type);
+ btrfs_set_dir_data_len(leaf, dir_item, 0);
+ btrfs_set_dir_name_len(leaf, dir_item, name_len);
+ btrfs_set_dir_transid(leaf, dir_item, trans->transid);
+ name_ptr = (unsigned long)(dir_item + 1);
+
+ write_extent_buffer(leaf, name, name_ptr, name_len);
+ btrfs_mark_buffer_dirty(leaf);
+
+second_insert:
+ /* FIXME, use some real flag for selecting the extra index */
+ if (root == root->fs_info->tree_root) {
+ ret = 0;
+ goto out;
+ }
+ btrfs_release_path(root, path);
+
+ btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
+ key.offset = index;
+ dir_item = insert_with_overflow(trans, root, path, &key, data_size,
+ name, name_len);
+ if (IS_ERR(dir_item)) {
+ ret2 = PTR_ERR(dir_item);
+ goto out;
+ }
+ leaf = path->nodes[0];
+ btrfs_cpu_key_to_disk(&disk_key, location);
+ btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
+ btrfs_set_dir_type(leaf, dir_item, type);
+ btrfs_set_dir_data_len(leaf, dir_item, 0);
+ btrfs_set_dir_name_len(leaf, dir_item, name_len);
+ btrfs_set_dir_transid(leaf, dir_item, trans->transid);
+ name_ptr = (unsigned long)(dir_item + 1);
+ write_extent_buffer(leaf, name, name_ptr, name_len);
+ btrfs_mark_buffer_dirty(leaf);
+out:
+ btrfs_free_path(path);
+ if (ret)
+ return ret;
+ if (ret2)
+ return ret2;
+ return 0;
+}
+
+/*
+ * lookup a directory item based on name. 'dir' is the objectid
+ * we're searching in, and 'mod' tells us if you plan on deleting the
+ * item (use mod < 0) or changing the options (use mod > 0)
+ */
+struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path, u64 dir,
+ const char *name, int name_len,
+ int mod)
+{
+ int ret;
+ struct btrfs_key key;
+ int ins_len = mod < 0 ? -1 : 0;
+ int cow = mod != 0;
+ struct btrfs_key found_key;
+ struct extent_buffer *leaf;
+
+ key.objectid = dir;
+ btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
+
+ key.offset = btrfs_name_hash(name, name_len);
+
+ ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
+ if (ret < 0)
+ return ERR_PTR(ret);
+ if (ret > 0) {
+ if (path->slots[0] == 0)
+ return NULL;
+ path->slots[0]--;
+ }
+
+ leaf = path->nodes[0];
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+ if (found_key.objectid != dir ||
+ btrfs_key_type(&found_key) != BTRFS_DIR_ITEM_KEY ||
+ found_key.offset != key.offset)
+ return NULL;
+
+ return btrfs_match_dir_item_name(root, path, name, name_len);
+}
+
+/*
+ * lookup a directory item based on index. 'dir' is the objectid
+ * we're searching in, and 'mod' tells us if you plan on deleting the
+ * item (use mod < 0) or changing the options (use mod > 0)
+ *
+ * The name is used to make sure the index really points to the name you were
+ * looking for.
+ */
+struct btrfs_dir_item *
+btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path, u64 dir,
+ u64 objectid, const char *name, int name_len,
+ int mod)
+{
+ int ret;
+ struct btrfs_key key;
+ int ins_len = mod < 0 ? -1 : 0;
+ int cow = mod != 0;
+
+ key.objectid = dir;
+ btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
+ key.offset = objectid;
+
+ ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
+ if (ret < 0)
+ return ERR_PTR(ret);
+ if (ret > 0)
+ return ERR_PTR(-ENOENT);
+ return btrfs_match_dir_item_name(root, path, name, name_len);
+}
+
+struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path, u64 dir,
+ const char *name, u16 name_len,
+ int mod)
+{
+ int ret;
+ struct btrfs_key key;
+ int ins_len = mod < 0 ? -1 : 0;
+ int cow = mod != 0;
+ struct btrfs_key found_key;
+ struct extent_buffer *leaf;
+
+ key.objectid = dir;
+ btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
+ key.offset = btrfs_name_hash(name, name_len);
+ ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
+ if (ret < 0)
+ return ERR_PTR(ret);
+ if (ret > 0) {
+ if (path->slots[0] == 0)
+ return NULL;
+ path->slots[0]--;
+ }
+
+ leaf = path->nodes[0];
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+ if (found_key.objectid != dir ||
+ btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY ||
+ found_key.offset != key.offset)
+ return NULL;
+
+ return btrfs_match_dir_item_name(root, path, name, name_len);
+}
+
+/*
+ * helper function to look at the directory item pointed to by 'path'
+ * this walks through all the entries in a dir item and finds one
+ * for a specific name.
+ */
+struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
+ struct btrfs_path *path,
+ const char *name, int name_len)
+{
+ struct btrfs_dir_item *dir_item;
+ unsigned long name_ptr;
+ u32 total_len;
+ u32 cur = 0;
+ u32 this_len;
+ struct extent_buffer *leaf;
+
+ leaf = path->nodes[0];
+ dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
+ total_len = btrfs_item_size_nr(leaf, path->slots[0]);
+ while (cur < total_len) {
+ this_len = sizeof(*dir_item) +
+ btrfs_dir_name_len(leaf, dir_item) +
+ btrfs_dir_data_len(leaf, dir_item);
+ name_ptr = (unsigned long)(dir_item + 1);
+
+ if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
+ memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
+ return dir_item;
+
+ cur += this_len;
+ dir_item = (struct btrfs_dir_item *)((char *)dir_item +
+ this_len);
+ }
+ return NULL;
+}
+
+/*
+ * given a pointer into a directory item, delete it. This
+ * handles items that have more than one entry in them.
+ */
+int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ struct btrfs_dir_item *di)
+{
+
+ struct extent_buffer *leaf;
+ u32 sub_item_len;
+ u32 item_len;
+ int ret = 0;
+
+ leaf = path->nodes[0];
+ sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
+ btrfs_dir_data_len(leaf, di);
+ item_len = btrfs_item_size_nr(leaf, path->slots[0]);
+ if (sub_item_len == item_len) {
+ ret = btrfs_del_item(trans, root, path);
+ } else {
+ /* MARKER */
+ unsigned long ptr = (unsigned long)di;
+ unsigned long start;
+
+ start = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
+ item_len - (ptr + sub_item_len - start));
+ ret = btrfs_truncate_item(trans, root, path,
+ item_len - sub_item_len, 1);
+ }
+ return 0;
+}
--
1.6.0.2
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