C++ btrfs_search_slot函数代码示例

static int remove_extent_ref(struct btrfs_root *root, u64 bytenr,
			     u64 num_bytes, u64 parent, u64 root_objectid)
{
	struct btrfs_trans_handle trans;
	struct btrfs_extent_item *item;
	struct btrfs_path *path;
	struct btrfs_key key;
	u64 refs;
	int ret;

	btrfs_init_dummy_trans(&trans);

	key.objectid = bytenr;
	key.type = BTRFS_EXTENT_ITEM_KEY;
	key.offset = num_bytes;

	path = btrfs_alloc_path();
	if (!path) {
		test_msg("Couldn't allocate path\n");
		return -ENOMEM;
	}

	path->leave_spinning = 1;
	ret = btrfs_search_slot(&trans, root, &key, path, 0, 1);
	if (ret) {
		test_msg("Couldn't find extent ref\n");
		btrfs_free_path(path);
		return ret;
	}

	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
			      struct btrfs_extent_item);
	refs = btrfs_extent_refs(path->nodes[0], item);
	btrfs_set_extent_refs(path->nodes[0], item, refs - 1);
	btrfs_release_path(path);

	key.objectid = bytenr;
	if (parent) {
		key.type = BTRFS_SHARED_BLOCK_REF_KEY;
		key.offset = parent;
	} else {
		key.type = BTRFS_TREE_BLOCK_REF_KEY;
		key.offset = root_objectid;
	}

	ret = btrfs_search_slot(&trans, root, &key, path, -1, 1);
	if (ret) {
		test_msg("Couldn't find backref %d\n", ret);
		btrfs_free_path(path);
		return ret;
	}
	btrfs_del_item(&trans, root, path);
	btrfs_free_path(path);
	return ret;
}

int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
		      *root, struct btrfs_key *key, struct btrfs_root_item
		      *item)
{
	struct btrfs_path *path;
	struct extent_buffer *l;
	int ret;
	int slot;
	unsigned long ptr;

	path = btrfs_alloc_path();
	BUG_ON(!path);
	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
	if (ret < 0)
		goto out;
	BUG_ON(ret != 0);
	l = path->nodes[0];
	slot = path->slots[0];
	ptr = btrfs_item_ptr_offset(l, slot);
	write_extent_buffer(l, item, ptr, sizeof(*item));
	btrfs_mark_buffer_dirty(path->nodes[0]);
out:
	btrfs_release_path(root, path);
	btrfs_free_path(path);
	return ret;
}

static int write_one_cache_group(struct btrfs_trans_handle *trans,
				 struct btrfs_root *root,
				 struct btrfs_path *path,
				 struct btrfs_block_group_cache *cache)
{
	int ret;
	int pending_ret;
	struct btrfs_root *extent_root = root->fs_info->extent_root;
	struct btrfs_block_group_item *bi;
	struct btrfs_key ins;

	ret = find_free_extent(trans, root, 0, 0, (u64)-1, &ins);
	if (ret)
		return ret;
	ret = btrfs_search_slot(trans, root->fs_info->extent_root,
				&cache->key, path, 0, 1);
	BUG_ON(ret);
	bi = btrfs_item_ptr(&path->nodes[0]->leaf, path->slots[0],
			    struct btrfs_block_group_item);
	memcpy(bi, &cache->item, sizeof(*bi));
	dirty_tree_block(trans, extent_root, path->nodes[0]);
	btrfs_release_path(extent_root, path);
	finish_current_insert(trans, root);
	pending_ret = run_pending(trans, root);
	if (ret)
		return ret;
	if (pending_ret)
		return pending_ret;
	return 0;

}

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);
}

static int remove_extent_item(struct btrfs_root *root, u64 bytenr,
			      u64 num_bytes)
{
	struct btrfs_trans_handle trans;
	struct btrfs_key key;
	struct btrfs_path *path;
	int ret;

	btrfs_init_dummy_trans(&trans);

	key.objectid = bytenr;
	key.type = BTRFS_EXTENT_ITEM_KEY;
	key.offset = num_bytes;

	path = btrfs_alloc_path();
	if (!path) {
		test_msg("Couldn't allocate path\n");
		return -ENOMEM;
	}
	path->leave_spinning = 1;

	ret = btrfs_search_slot(&trans, root, &key, path, -1, 1);
	if (ret) {
		test_msg("Didn't find our key %d\n", ret);
		btrfs_free_path(path);
		return ret;
	}
	btrfs_del_item(&trans, root, path);
	btrfs_free_path(path);
	return 0;
}

/* drop the root item for 'key' from 'root' */
int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
		   struct btrfs_key *key)
{
	struct btrfs_path *path;
	int ret;
	u32 refs;
	struct btrfs_root_item *ri;
	struct extent_buffer *leaf;

	path = btrfs_alloc_path();
	BUG_ON(!path);
	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
	if (ret < 0)
		goto out;

	BUG_ON(ret != 0);
	leaf = path->nodes[0];
	ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);

	refs = btrfs_disk_root_refs(leaf, ri);
	BUG_ON(refs != 0);
	ret = btrfs_del_item(trans, root, path);
out:
	btrfs_free_path(path);
	return ret;
}

int btrfs_find_highest_inode(struct btrfs_root *root, u64 *objectid)
{
	struct btrfs_path *path;
	int ret;
	struct extent_buffer *l;
	struct btrfs_key search_key;
	struct btrfs_key found_key;
	int slot;

	path = btrfs_alloc_path();
	BUG_ON(!path);

	search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
	search_key.type = -1;
	search_key.offset = (u64)-1;
	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
	if (ret < 0)
		goto error;
	BUG_ON(ret == 0);
	if (path->slots[0] > 0) {
		slot = path->slots[0] - 1;
		l = path->nodes[0];
		btrfs_item_key_to_cpu(l, &found_key, slot);
		*objectid = found_key.objectid;
	} else {
		*objectid = BTRFS_FIRST_FREE_OBJECTID;
	}
	ret = 0;
error:
	btrfs_free_path(path);
	return ret;
}

/*
 * this makes the path point to (logical EXTENT_ITEM *)
 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
 * tree blocks and <0 on error.
 */
int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
			struct btrfs_path *path, struct btrfs_key *found_key,
			u64 *flags_ret)
{
	int ret;
	u64 flags;
	u32 item_size;
	struct extent_buffer *eb;
	struct btrfs_extent_item *ei;
	struct btrfs_key key;

	key.type = BTRFS_EXTENT_ITEM_KEY;
	key.objectid = logical;
	key.offset = (u64)-1;

	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
	if (ret < 0)
		return ret;
	ret = btrfs_previous_item(fs_info->extent_root, path,
					0, BTRFS_EXTENT_ITEM_KEY);
	if (ret < 0)
		return ret;

	btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
	if (found_key->type != BTRFS_EXTENT_ITEM_KEY ||
	    found_key->objectid > logical ||
	    found_key->objectid + found_key->offset <= logical) {
		pr_debug("logical %llu is not within any extent\n",
			 (unsigned long long)logical);
		return -ENOENT;
	}

	eb = path->nodes[0];
	item_size = btrfs_item_size_nr(eb, path->slots[0]);
	BUG_ON(item_size < sizeof(*ei));

	ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
	flags = btrfs_extent_flags(eb, ei);

	pr_debug("logical %llu is at position %llu within the extent (%llu "
		 "EXTENT_ITEM %llu) flags %#llx size %u\n",
		 (unsigned long long)logical,
		 (unsigned long long)(logical - found_key->objectid),
		 (unsigned long long)found_key->objectid,
		 (unsigned long long)found_key->offset,
		 (unsigned long long)flags, item_size);

	WARN_ON(!flags_ret);
	if (flags_ret) {
		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
			*flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
		else if (flags & BTRFS_EXTENT_FLAG_DATA)
			*flags_ret = BTRFS_EXTENT_FLAG_DATA;
		else
			BUG_ON(1);
		return 0;
	}

	return -EIO;
}

/*
 * copy the data in 'item' into the btree
 */
int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
		      *root, struct btrfs_key *key, struct btrfs_root_item
		      *item)
{
	struct btrfs_path *path;
	struct extent_buffer *l;
	int ret;
	int slot;
	unsigned long ptr;

	path = btrfs_alloc_path();
	BUG_ON(!path);
	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
	if (ret < 0)
		goto out;

	if (ret != 0) {
		btrfs_print_leaf(root, path->nodes[0]);
		printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
		       (unsigned long long)key->objectid, key->type,
		       (unsigned long long)key->offset);
		BUG_ON(1);
	}

	l = path->nodes[0];
	slot = path->slots[0];
	ptr = btrfs_item_ptr_offset(l, slot);
	write_extent_buffer(l, item, ptr, sizeof(*item));
	btrfs_mark_buffer_dirty(path->nodes[0]);
out:
	btrfs_free_path(path);
	return ret;
}

static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
			 *root, u64 blocknr)
{
	struct btrfs_path path;
	int ret;
	struct btrfs_key key;
	struct btrfs_leaf *l;
	struct btrfs_extent_item *item;
	struct btrfs_key ins;
	u32 refs;

	find_free_extent(trans, root->fs_info->extent_root, 0, 0, (u64)-1,
			 &ins);
	btrfs_init_path(&path);
	key.objectid = blocknr;
	key.flags = 0;
	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
	key.offset = 1;
	ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
				0, 1);
	if (ret != 0)
		BUG();
	BUG_ON(ret != 0);
	l = &path.nodes[0]->leaf;
	item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
	refs = btrfs_extent_refs(item);
	btrfs_set_extent_refs(item, refs + 1);

	BUG_ON(list_empty(&path.nodes[0]->dirty));
	btrfs_release_path(root->fs_info->extent_root, &path);
	finish_current_insert(trans, root->fs_info->extent_root);
	run_pending(trans, root->fs_info->extent_root);
	return 0;
}

int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
		   struct btrfs_key *key)
{
	struct btrfs_path *path;
	int ret;
	u32 refs;
	struct btrfs_root_item *ri;
	struct extent_buffer *leaf;

	path = btrfs_alloc_path();
	BUG_ON(!path);
	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
	if (ret < 0)
		goto out;
	if (ret) {
btrfs_print_leaf(root, path->nodes[0]);
printk("failed to del %llu %u %llu\n",
	(unsigned long long)key->objectid,
	key->type,
	(unsigned long long)key->offset);

	}
	BUG_ON(ret != 0);
	leaf = path->nodes[0];
	ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);

	refs = btrfs_disk_root_refs(leaf, ri);
	BUG_ON(refs != 0);
	ret = btrfs_del_item(trans, root, path);
out:
	btrfs_release_path(root, path);
	btrfs_free_path(path);
	return ret;
}

static int __inode_info(u64 inum, u64 ioff, u8 key_type,
			struct btrfs_root *fs_root, struct btrfs_path *path,
			struct btrfs_key *found_key)
{
	int ret;
	struct btrfs_key key;
	struct extent_buffer *eb;

	key.type = key_type;
	key.objectid = inum;
	key.offset = ioff;

	ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
	if (ret < 0)
		return ret;

	eb = path->nodes[0];
	if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
		ret = btrfs_next_leaf(fs_root, path);
		if (ret)
			return ret;
		eb = path->nodes[0];
	}

	btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
	if (found_key->type != key.type || found_key->objectid != key.objectid)
		return 1;

	return 0;
}

int btrfs_del_orphan_item(struct btrfs_trans_handle *trans,
			  struct btrfs_root *root, u64 offset)
{
	struct btrfs_path *path;
	struct btrfs_key key;
	int ret = 0;

	key.objectid = BTRFS_ORPHAN_OBJECTID;
	btrfs_set_key_type(&key, BTRFS_ORPHAN_ITEM_KEY);
	key.offset = offset;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret)
		goto out;

	ret = btrfs_del_item(trans, root, path);

out:
	btrfs_free_path(path);
	return ret;
}

/*
 * Change inode flags to given value
 */
int btrfs_change_inode_flags(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root, u64 ino, u64 flags)
{
	struct btrfs_inode_item *item;
	struct btrfs_path *path;
	struct btrfs_key key;
	int ret;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	key.objectid = ino;
	key.type = BTRFS_INODE_ITEM_KEY;
	key.offset = 0;

	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
	if (ret > 0) {
		ret = -ENOENT;
		goto out;
	}
	if (ret < 0)
		goto out;

	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
			      struct btrfs_inode_item);
	btrfs_set_inode_flags(path->nodes[0], item, flags);
	btrfs_mark_buffer_dirty(path->nodes[0]);
out:
	btrfs_free_path(path);
	return ret;
}

struct btrfs_free_space_info *
search_free_space_info(struct btrfs_trans_handle *trans,
                       struct btrfs_fs_info *fs_info,
                       struct btrfs_block_group_cache *block_group,
                       struct btrfs_path *path, int cow)
{
    struct btrfs_root *root = fs_info->free_space_root;
    struct btrfs_key key;
    int ret;

    key.objectid = block_group->key.objectid;
    key.type = BTRFS_FREE_SPACE_INFO_KEY;
    key.offset = block_group->key.offset;

    ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
    if (ret < 0)
        return ERR_PTR(ret);
    if (ret != 0) {
        btrfs_warn(fs_info, "missing free space info for %llu\n",
                   block_group->key.objectid);
        ASSERT(0);
        return ERR_PTR(-ENOENT);
    }

    return btrfs_item_ptr(path->nodes[0], path->slots[0],
                          struct btrfs_free_space_info);
}