btrfs-progs/kernel-shared/dir-item.c

/*
 * 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 "kerncompat.h"
#include <linux/limits.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "kernel-lib/bitops.h"
#include "kernel-shared/ctree.h"
#include "kernel-shared/disk-io.h"
#include "kernel-shared/accessors.h"
#include "kernel-shared/extent_io.h"
#include "kernel-shared/uapi/btrfs_tree.h"

struct btrfs_trans_handle;

/*
 * 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 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);
		btrfs_extend_item(path, data_size);
		ret = 0;
	}
	if (ret < 0)
		return ERR_PTR(ret);
	WARN_ON(ret > 0);
	leaf = path->nodes[0];
	ptr = btrfs_item_ptr(leaf, path->slots[0], char);
	BUG_ON(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, 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;
	key.type = BTRFS_XATTR_ITEM_KEY;
	key.offset = btrfs_name_hash(name, name_len);
	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	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 aren't
	 * 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_flags(leaf, dir_item, BTRFS_FT_XATTR);
	btrfs_set_dir_name_len(leaf, dir_item, name_len);
	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).
 * Will return 0 or -ENOMEM
 */
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;
	key.type = BTRFS_DIR_ITEM_KEY;
	key.offset = btrfs_name_hash(name, name_len);
	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
	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);

		/* Continue to insert item if existed */
		if (ret == -EEXIST) {
			ret = 0;
			goto insert;
		} else {
			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_flags(leaf, dir_item, type);
	btrfs_set_dir_data_len(leaf, dir_item, 0);
	btrfs_set_dir_name_len(leaf, dir_item, name_len);
	name_ptr = (unsigned long)(dir_item + 1);

	write_extent_buffer(leaf, name, name_ptr, name_len);
	btrfs_mark_buffer_dirty(leaf);

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(path);

	key.type = 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);
		if (ret2 == -EEXIST)
			ret = 0;
		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_flags(leaf, dir_item, type);
	btrfs_set_dir_data_len(leaf, dir_item, 0);
	btrfs_set_dir_name_len(leaf, dir_item, name_len);
	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;
}

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;
	key.type = 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 ||
	    found_key.type != BTRFS_DIR_ITEM_KEY ||
	    found_key.offset != key.offset)
		return NULL;

	return btrfs_match_dir_item_name(root, path, name, name_len);
}

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;
	key.type = 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);
}

/*
 * 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 is longer than @item_len, then it means the
	 * name_len is just corrupted.
	 * No good idea to know if there is anything we can recover from
	 * the corrupted item.
	 * Just delete the item.
	 */
	if (sub_item_len >= item_len) {
		ret = btrfs_del_item(trans, root, path);
	} else {
		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;
}

static int verify_dir_item(struct btrfs_root *root,
		    struct extent_buffer *leaf,
		    struct btrfs_dir_item *dir_item)
{
	u16 namelen = BTRFS_NAME_LEN;
	u8 type = btrfs_dir_ftype(leaf, dir_item);

	if (type == BTRFS_FT_XATTR)
		namelen = XATTR_NAME_MAX;

	if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
		fprintf(stderr, "invalid dir item name len: %u\n",
		       (unsigned)btrfs_dir_data_len(leaf, dir_item));
		return 1;
	}

	/* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
	if ((btrfs_dir_data_len(leaf, dir_item) +
	     btrfs_dir_name_len(leaf, dir_item)) >
			BTRFS_MAX_XATTR_SIZE(root->fs_info)) {
		fprintf(stderr, "invalid dir item name + data len: %u + %u\n",
		       (unsigned)btrfs_dir_name_len(leaf, dir_item),
		       (unsigned)btrfs_dir_data_len(leaf, dir_item));
		return 1;
	}

	return 0;
}

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(leaf, path->slots[0]);
	if (verify_dir_item(root, leaf, dir_item))
		return NULL;

	while(cur < total_len) {
		this_len = sizeof(*dir_item) +
			btrfs_dir_name_len(leaf, dir_item) +
			btrfs_dir_data_len(leaf, dir_item);
		if (this_len > (total_len - cur)) {
			fprintf(stderr, "invalid dir item size\n");
			return NULL;
		}

		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;
}