C++ btrfs_item_key_to_cpu函数代码示例

/*
 * read tree blocks and add keys where required.
 */
static int __add_missing_keys(struct btrfs_fs_info *fs_info,
			      struct list_head *head)
{
	struct list_head *pos;
	struct extent_buffer *eb;

	list_for_each(pos, head) {
		struct __prelim_ref *ref;
		ref = list_entry(pos, struct __prelim_ref, list);

		if (ref->parent)
			continue;
		if (ref->key_for_search.type)
			continue;
		BUG_ON(!ref->wanted_disk_byte);
		eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
				     fs_info->tree_root->leafsize, 0);
		if (!eb || !extent_buffer_uptodate(eb)) {
			free_extent_buffer(eb);
			return -EIO;
		}
		btrfs_tree_read_lock(eb);
		if (btrfs_header_level(eb) == 0)
			btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
		else
			btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
		btrfs_tree_read_unlock(eb);
		free_extent_buffer(eb);
	}
	return 0;
}

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;
}

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);
}

/*
 * 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;
}

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;
}

static void free_space_set_bits(struct btrfs_block_group_cache *block_group,
                                struct btrfs_path *path, u64 *start, u64 *size,
                                int bit)
{
    struct extent_buffer *leaf;
    struct btrfs_key key;
    u64 end = *start + *size;
    u64 found_start, found_end;
    unsigned long ptr, first, last;

    leaf = path->nodes[0];
    btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
    ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);

    found_start = key.objectid;
    found_end = key.objectid + key.offset;
    ASSERT(*start >= found_start && *start < found_end);
    ASSERT(end > found_start);

    if (end > found_end)
        end = found_end;

    ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
    first = div_u64(*start - found_start, block_group->sectorsize);
    last = div_u64(end - found_start, block_group->sectorsize);
    if (bit)
        extent_buffer_bitmap_set(leaf, ptr, first, last - first);
    else
        extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
    btrfs_mark_buffer_dirty(leaf);

    *size -= end - *start;
    *start = end;
}

static int map_one_extent(struct btrfs_fs_info *fs_info,
			  u64 *logical_ret, u64 *len_ret, int search_forward)
{
	struct btrfs_path *path;
	struct btrfs_key key;
	u64 logical;
	u64 len = 0;
	int ret = 0;

	BUG_ON(!logical_ret);
	logical = *logical_ret;

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

	key.objectid = logical;
	key.type = 0;
	key.offset = 0;

	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path,
				0, 0);
	if (ret < 0)
		goto out;
	BUG_ON(ret == 0);
	ret = 0;

again:
	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
	if ((search_forward && key.objectid < logical) ||
	    (!search_forward && key.objectid > logical) ||
	    (key.type != BTRFS_EXTENT_ITEM_KEY &&
	     key.type != BTRFS_METADATA_ITEM_KEY)) {
		if (!search_forward)
			ret = btrfs_previous_extent_item(fs_info->extent_root,
							 path, 0);
		else
			ret = btrfs_next_extent_item(fs_info->extent_root,
						     path, 0);
		if (ret)
			goto out;
		goto again;
	}
	logical = key.objectid;
	if (key.type == BTRFS_METADATA_ITEM_KEY)
		len = fs_info->nodesize;
	else
		len = key.offset;

out:
	btrfs_free_path(path);
	if (!ret) {
		*logical_ret = logical;
		if (len_ret)
			*len_ret = len;
	}
	return ret;
}

static struct dentry *btrfs_get_parent(struct dentry *child)
{
    struct inode *dir = child->d_inode;
    struct btrfs_root *root = BTRFS_I(dir)->root;
    struct btrfs_key key;
    struct btrfs_path *path;
    struct extent_buffer *leaf;
    int slot;
    u64 objectid;
    int ret;

    path = btrfs_alloc_path();

    key.objectid = dir->i_ino;
    btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
    key.offset = (u64)-1;

    ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
    if (ret < 0) {
        /* Error */
        btrfs_free_path(path);
        return ERR_PTR(ret);
    }
    leaf = path->nodes[0];
    slot = path->slots[0];
    if (ret) {
        /* btrfs_search_slot() returns the slot where we'd want to
           insert a backref for parent inode #0xFFFFFFFFFFFFFFFF.
           The _real_ backref, telling us what the parent inode
           _actually_ is, will be in the slot _before_ the one
           that btrfs_search_slot() returns. */
        if (!slot) {
            /* Unless there is _no_ key in the tree before... */
            btrfs_free_path(path);
            return ERR_PTR(-EIO);
        }
        slot--;
    }

    btrfs_item_key_to_cpu(leaf, &key, slot);
    btrfs_free_path(path);

    if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY)
        return ERR_PTR(-EINVAL);

    objectid = key.offset;

    /* If we are already at the root of a subvol, return the real root */
    if (objectid == dir->i_ino)
        return dget(dir->i_sb->s_root);

    /* Build a new key for the inode item */
    key.objectid = objectid;
    btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
    key.offset = 0;

    return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
}

int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
{
	struct extent_buffer *leaf;
	struct btrfs_path *path;
	struct btrfs_key key;
	int err = 0;
	int ret;

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

	key.objectid = BTRFS_ORPHAN_OBJECTID;
	key.type = BTRFS_ORPHAN_ITEM_KEY;
	key.offset = 0;

	while (1) {
		ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
		if (ret < 0) {
			err = ret;
			break;
		}

		leaf = path->nodes[0];
		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
			ret = btrfs_next_leaf(tree_root, path);
			if (ret < 0)
				err = ret;
			if (ret != 0)
				break;
			leaf = path->nodes[0];
		}

		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
		btrfs_release_path(tree_root, path);

		if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
		    key.type != BTRFS_ORPHAN_ITEM_KEY)
			break;

		ret = btrfs_find_dead_roots(tree_root, key.offset);
		if (ret) {
			err = ret;
			break;
		}

		key.offset++;
	}

	btrfs_free_path(path);
	return err;
}

static struct dentry *btrfs_get_parent(struct dentry *child)
{
	struct inode *dir = d_inode(child);
	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
	struct btrfs_root *root = BTRFS_I(dir)->root;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	struct btrfs_root_ref *ref;
	struct btrfs_key key;
	struct btrfs_key found_key;
	int ret;

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

	if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
		key.objectid = root->root_key.objectid;
		key.type = BTRFS_ROOT_BACKREF_KEY;
		key.offset = (u64)-1;
		root = fs_info->tree_root;
	} else {
		key.objectid = btrfs_ino(BTRFS_I(dir));
		key.type = BTRFS_INODE_REF_KEY;
		key.offset = (u64)-1;
	}

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto fail;

	BUG_ON(ret == 0); /* Key with offset of -1 found */
	if (path->slots[0] == 0) {
		ret = -ENOENT;
		goto fail;
	}

	path->slots[0]--;
	leaf = path->nodes[0];

	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
	if (found_key.objectid != key.objectid || found_key.type != key.type) {
		ret = -ENOENT;
		goto fail;
	}

	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
		ref = btrfs_item_ptr(leaf, path->slots[0],
				     struct btrfs_root_ref);
		key.objectid = btrfs_root_ref_dirid(leaf, ref);
	} else {

/*
 * Find a free inode index for later btrfs_add_link().
 * Currently just search from the largest dir_index and +1.
 */
static int btrfs_find_free_dir_index(struct btrfs_root *root, u64 dir_ino,
				     u64 *ret_ino)
{
	struct btrfs_path *path;
	struct btrfs_key key;
	struct btrfs_key found_key;
	u64 ret_val = 2;
	int ret = 0;

	if (!ret_ino)
		return 0;

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

	key.objectid = dir_ino;
	key.type = BTRFS_DIR_INDEX_KEY;
	key.offset = (u64)-1;

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto out;
	ret = 0;
	if (path->slots[0] == 0) {
		ret = btrfs_prev_leaf(root, path);
		if (ret < 0)
			goto out;
		if (ret > 0) {
			/*
			 * This shouldn't happen since there must be a leaf
			 * containing the DIR_ITEM.
			 * Can only happen when the previous leaf is corrupted.
			 */
			ret = -EIO;
			goto out;
		}
	} else {
		path->slots[0]--;
	}
	btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
	if (found_key.objectid != dir_ino ||
	    found_key.type != BTRFS_DIR_INDEX_KEY)
		goto out;
	ret_val = found_key.offset + 1;
out:
	btrfs_free_path(path);
	if (ret == 0)
		*ret_ino = ret_val;
	return ret;
}

static struct btrfs_csum_item *
btrfs_lookup_csum(struct btrfs_trans_handle *trans,
                  struct btrfs_root *root,
                  struct btrfs_path *path,
                  u64 bytenr, int cow)
{
    int ret;
    struct btrfs_key file_key;
    struct btrfs_key found_key;
    struct btrfs_csum_item *item;
    struct extent_buffer *leaf;
    u64 csum_offset = 0;
    u16 csum_size =
        btrfs_super_csum_size(root->fs_info->super_copy);
    int csums_in_item;

    file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
    file_key.offset = bytenr;
    btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
    ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
    if (ret < 0)
        goto fail;
    leaf = path->nodes[0];
    if (ret > 0) {
        ret = 1;
        if (path->slots[0] == 0)
            goto fail;
        path->slots[0]--;
        btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
        if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
            goto fail;

        csum_offset = (bytenr - found_key.offset) / root->sectorsize;
        csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
        csums_in_item /= csum_size;

        if (csum_offset >= csums_in_item) {
            ret = -EFBIG;
            goto fail;
        }
    }
    item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
    item = (struct btrfs_csum_item *)((unsigned char *)item +
                                      csum_offset * csum_size);
    return item;
fail:
    if (ret > 0)
        ret = -ENOENT;
    return ERR_PTR(ret);
}

struct btrfs_dir_item *
btrfs_search_dir_index_item(struct btrfs_root *root,
			    struct btrfs_path *path, u64 dirid,
			    const char *name, int name_len)
{
	struct extent_buffer *leaf;
	struct btrfs_dir_item *di;
	struct btrfs_key key;
	u32 nritems;
	int ret;

	key.objectid = dirid;
	key.type = BTRFS_DIR_INDEX_KEY;
	key.offset = 0;

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

	leaf = path->nodes[0];
	nritems = btrfs_header_nritems(leaf);

	while (1) {
		if (path->slots[0] >= nritems) {
			ret = btrfs_next_leaf(root, path);
			if (ret < 0)
				return ERR_PTR(ret);
			if (ret > 0)
				break;
			leaf = path->nodes[0];
			nritems = btrfs_header_nritems(leaf);
			continue;
		}

		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
		if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
			break;

		di = btrfs_match_dir_item_name(root->fs_info, path,
					       name, name_len);
		if (di)
			return di;

		path->slots[0]++;
	}
	return NULL;
}

static int ondisk_del(struct btrfs_trans_handle *trans,
		      struct btrfs_dedup_info *dedup_info, u64 bytenr)
{
	struct btrfs_root *dedup_root = dedup_info->dedup_root;
	struct btrfs_path *path;
	struct btrfs_key key;
	int ret;

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

	key.objectid = bytenr;
	key.type = BTRFS_DEDUP_BYTENR_ITEM_KEY;
	key.offset = 0;

	mutex_lock(&dedup_info->lock);

	ret = ondisk_search_bytenr(trans, dedup_info, path, bytenr, 1);
	if (ret <= 0)
		goto out;

	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
	btrfs_del_item(trans, dedup_root, path);
	btrfs_release_path(path);

	/* Search for hash item and delete it */
	key.objectid = key.offset;
	key.type = BTRFS_DEDUP_HASH_ITEM_KEY;
	key.offset = bytenr;

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

out:
	btrfs_free_path(path);
	mutex_unlock(&dedup_info->lock);
	return ret;
}

/*
 * lookup the root with the highest offset for a given objectid.  The key we do
 * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
 * on error.
 */
int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
			struct btrfs_root_item *item, struct btrfs_key *key)
{
	struct btrfs_path *path;
	struct btrfs_key search_key;
	struct btrfs_key found_key;
	struct extent_buffer *l;
	int ret;
	int slot;

	search_key.objectid = objectid;
	search_key.type = BTRFS_ROOT_ITEM_KEY;
	search_key.offset = (u64)-1;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
	if (ret < 0)
		goto out;

	BUG_ON(ret == 0);
	if (path->slots[0] == 0) {
		ret = 1;
		goto out;
	}
	l = path->nodes[0];
	slot = path->slots[0] - 1;
	btrfs_item_key_to_cpu(l, &found_key, slot);
	if (found_key.objectid != objectid ||
	    found_key.type != BTRFS_ROOT_ITEM_KEY) {
		ret = 1;
		goto out;
	}
	if (item)
		read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
				   sizeof(*item));
	if (key)
		memcpy(key, &found_key, sizeof(found_key));
	ret = 0;
out:
	btrfs_free_path(path);
	return ret;
}