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-rw-r--r--fs/btrfs/dir-item.c439
1 files changed, 439 insertions, 0 deletions
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
new file mode 100644
index 000000000..fdab48c1a
--- /dev/null
+++ b/fs/btrfs/dir-item.c
@@ -0,0 +1,439 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle. All rights reserved.
+ */
+
+#include "ctree.h"
+#include "disk-io.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)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ int ret;
+ char *ptr;
+ 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(fs_info, path, name, name_len);
+ if (di)
+ return ERR_PTR(-EEXIST);
+ btrfs_extend_item(path, data_size);
+ } else if (ret < 0)
+ return ERR_PTR(ret);
+ WARN_ON(ret > 0);
+ leaf = path->nodes[0];
+ ptr = btrfs_item_ptr(leaf, path->slots[0], char);
+ ASSERT(data_size <= btrfs_item_size(leaf, path->slots[0]));
+ ptr += btrfs_item_size(leaf, path->slots[0]) - 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,
+ struct btrfs_path *path, u64 objectid,
+ const char *name, u16 name_len,
+ const void *data, u16 data_len)
+{
+ int ret = 0;
+ 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;
+
+ if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info))
+ return -ENOSPC;
+
+ key.objectid = objectid;
+ key.type = BTRFS_XATTR_ITEM_KEY;
+ key.offset = btrfs_name_hash(name, name_len);
+
+ data_size = sizeof(*dir_item) + name_len + data_len;
+ dir_item = insert_with_overflow(trans, root, path, &key, data_size,
+ name, name_len);
+ if (IS_ERR(dir_item))
+ return PTR_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]);
+
+ 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).
+ * Will return 0 or -ENOMEM
+ */
+int btrfs_insert_dir_item(struct btrfs_trans_handle *trans,
+ const struct fscrypt_str *name, struct btrfs_inode *dir,
+ struct btrfs_key *location, u8 type, u64 index)
+{
+ int ret = 0;
+ int ret2 = 0;
+ struct btrfs_root *root = dir->root;
+ 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 = btrfs_ino(dir);
+ key.type = BTRFS_DIR_ITEM_KEY;
+ key.offset = btrfs_name_hash(name->name, name->len);
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ btrfs_cpu_key_to_disk(&disk_key, location);
+
+ data_size = sizeof(*dir_item) + name->len;
+ dir_item = insert_with_overflow(trans, root, path, &key, data_size,
+ name->name, name->len);
+ if (IS_ERR(dir_item)) {
+ ret = PTR_ERR(dir_item);
+ if (ret == -EEXIST)
+ goto second_insert;
+ goto out_free;
+ }
+
+ leaf = path->nodes[0];
+ 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, 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_free;
+ }
+ btrfs_release_path(path);
+
+ ret2 = btrfs_insert_delayed_dir_index(trans, name->name, name->len, dir,
+ &disk_key, type, index);
+out_free:
+ btrfs_free_path(path);
+ if (ret)
+ return ret;
+ if (ret2)
+ return ret2;
+ return 0;
+}
+
+static struct btrfs_dir_item *btrfs_lookup_match_dir(
+ struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, struct btrfs_path *path,
+ struct btrfs_key *key, const char *name,
+ int name_len, int mod)
+{
+ const int ins_len = (mod < 0 ? -1 : 0);
+ const int cow = (mod != 0);
+ int ret;
+
+ 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->fs_info, path, name, name_len);
+}
+
+/*
+ * Lookup for a directory item by name.
+ *
+ * @trans: The transaction handle to use. Can be NULL if @mod is 0.
+ * @root: The root of the target tree.
+ * @path: Path to use for the search.
+ * @dir: The inode number (objectid) of the directory.
+ * @name: The name associated to the directory entry we are looking for.
+ * @name_len: The length of the name.
+ * @mod: Used to indicate if the tree search is meant for a read only
+ * lookup, for a modification lookup or for a deletion lookup, so
+ * its value should be 0, 1 or -1, respectively.
+ *
+ * Returns: NULL if the dir item does not exists, an error pointer if an error
+ * happened, or a pointer to a dir item if a dir item exists for the given name.
+ */
+struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path, u64 dir,
+ const struct fscrypt_str *name,
+ int mod)
+{
+ struct btrfs_key key;
+ struct btrfs_dir_item *di;
+
+ key.objectid = dir;
+ key.type = BTRFS_DIR_ITEM_KEY;
+ key.offset = btrfs_name_hash(name->name, name->len);
+
+ di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
+ name->len, mod);
+ if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
+ return NULL;
+
+ return di;
+}
+
+int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
+ const struct fscrypt_str *name)
+{
+ int ret;
+ struct btrfs_key key;
+ struct btrfs_dir_item *di;
+ int data_size;
+ struct extent_buffer *leaf;
+ int slot;
+ struct btrfs_path *path;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ key.objectid = dir;
+ key.type = BTRFS_DIR_ITEM_KEY;
+ key.offset = btrfs_name_hash(name->name, name->len);
+
+ di = btrfs_lookup_match_dir(NULL, root, path, &key, name->name,
+ name->len, 0);
+ if (IS_ERR(di)) {
+ ret = PTR_ERR(di);
+ /* Nothing found, we're safe */
+ if (ret == -ENOENT) {
+ ret = 0;
+ goto out;
+ }
+
+ if (ret < 0)
+ goto out;
+ }
+
+ /* we found an item, look for our name in the item */
+ if (di) {
+ /* our exact name was found */
+ ret = -EEXIST;
+ goto out;
+ }
+
+ /* See if there is room in the item to insert this name. */
+ data_size = sizeof(*di) + name->len;
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+ if (data_size + btrfs_item_size(leaf, slot) +
+ sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
+ ret = -EOVERFLOW;
+ } else {
+ /* plenty of insertion room */
+ ret = 0;
+ }
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+/*
+ * Lookup for a directory index item by name and index number.
+ *
+ * @trans: The transaction handle to use. Can be NULL if @mod is 0.
+ * @root: The root of the target tree.
+ * @path: Path to use for the search.
+ * @dir: The inode number (objectid) of the directory.
+ * @index: The index number.
+ * @name: The name associated to the directory entry we are looking for.
+ * @name_len: The length of the name.
+ * @mod: Used to indicate if the tree search is meant for a read only
+ * lookup, for a modification lookup or for a deletion lookup, so
+ * its value should be 0, 1 or -1, respectively.
+ *
+ * Returns: NULL if the dir index item does not exists, an error pointer if an
+ * error happened, or a pointer to a dir item if the dir index item exists and
+ * matches the criteria (name and index number).
+ */
+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 index, const struct fscrypt_str *name, int mod)
+{
+ struct btrfs_dir_item *di;
+ struct btrfs_key key;
+
+ key.objectid = dir;
+ key.type = BTRFS_DIR_INDEX_KEY;
+ key.offset = index;
+
+ di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
+ name->len, mod);
+ if (di == ERR_PTR(-ENOENT))
+ return NULL;
+
+ return di;
+}
+
+struct btrfs_dir_item *
+btrfs_search_dir_index_item(struct btrfs_root *root, struct btrfs_path *path,
+ u64 dirid, const struct fscrypt_str *name)
+{
+ struct btrfs_dir_item *di;
+ struct btrfs_key key;
+ int ret;
+
+ key.objectid = dirid;
+ key.type = BTRFS_DIR_INDEX_KEY;
+ key.offset = 0;
+
+ btrfs_for_each_slot(root, &key, &key, path, ret) {
+ if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
+ break;
+
+ di = btrfs_match_dir_item_name(root->fs_info, path,
+ name->name, name->len);
+ if (di)
+ return di;
+ }
+ /* Adjust return code if the key was not found in the next leaf. */
+ if (ret > 0)
+ ret = 0;
+
+ return ERR_PTR(ret);
+}
+
+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)
+{
+ struct btrfs_key key;
+ struct btrfs_dir_item *di;
+
+ key.objectid = dir;
+ key.type = BTRFS_XATTR_ITEM_KEY;
+ key.offset = btrfs_name_hash(name, name_len);
+
+ di = btrfs_lookup_match_dir(trans, root, path, &key, name, name_len, mod);
+ if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
+ return NULL;
+
+ return di;
+}
+
+/*
+ * 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_fs_info *fs_info,
+ 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(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(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));
+ btrfs_truncate_item(path, item_len - sub_item_len, 1);
+ }
+ return ret;
+}
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