C++ btrfs_release_path函数代码示例

static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
			      struct btrfs_path *path,
			      iterate_irefs_t *iterate, void *ctx)
{
	int ret = 0;
	int slot;
	u32 cur;
	u32 len;
	u32 name_len;
	u64 parent = 0;
	int found = 0;
	struct extent_buffer *eb;
	struct btrfs_item *item;
	struct btrfs_inode_ref *iref;
	struct btrfs_key found_key;

	while (!ret) {
		ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
				     &found_key);
		if (ret < 0)
			break;
		if (ret) {
			ret = found ? 0 : -ENOENT;
			break;
		}
		++found;

		parent = found_key.offset;
		slot = path->slots[0];
		eb = btrfs_clone_extent_buffer(path->nodes[0]);
		if (!eb) {
			ret = -ENOMEM;
			break;
		}
		extent_buffer_get(eb);
		btrfs_release_path(path);

		item = btrfs_item_nr(slot);
		iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);

		for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
			name_len = btrfs_inode_ref_name_len(eb, iref);
			/* path must be released before calling iterate()! */
			pr_debug("following ref at offset %u for inode %llu in "
				 "tree %llu\n", cur, found_key.objectid,
				 fs_root->objectid);
			ret = iterate(parent, name_len,
				      (unsigned long)(iref + 1), eb, ctx);
			if (ret)
				break;
			len = sizeof(*iref) + name_len;
			iref = (struct btrfs_inode_ref *)((char *)iref + len);
		}
		free_extent_buffer(eb);
	}

	btrfs_release_path(path);

	return ret;
}

/*
 * this iterates to turn a name (from iref/extref) into a full filesystem path.
 * Elements of the path are separated by '/' and the path is guaranteed to be
 * 0-terminated. the path is only given within the current file system.
 * Therefore, it never starts with a '/'. the caller is responsible to provide
 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
 * the start point of the resulting string is returned. this pointer is within
 * dest, normally.
 * in case the path buffer would overflow, the pointer is decremented further
 * as if output was written to the buffer, though no more output is actually
 * generated. that way, the caller can determine how much space would be
 * required for the path to fit into the buffer. in that case, the returned
 * value will be smaller than dest. callers must check this!
 */
char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
			u32 name_len, unsigned long name_off,
			struct extent_buffer *eb_in, u64 parent,
			char *dest, u32 size)
{
	int slot;
	u64 next_inum;
	int ret;
	s64 bytes_left = ((s64)size) - 1;
	struct extent_buffer *eb = eb_in;
	struct btrfs_key found_key;
	struct btrfs_inode_ref *iref;

	if (bytes_left >= 0)
		dest[bytes_left] = '\0';

	while (1) {
		bytes_left -= name_len;
		if (bytes_left >= 0)
			read_extent_buffer(eb, dest + bytes_left,
					   name_off, name_len);
		if (eb != eb_in)
			free_extent_buffer(eb);
		ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
		if (ret > 0)
			ret = -ENOENT;
		if (ret)
			break;

		next_inum = found_key.offset;

		/* regular exit ahead */
		if (parent == next_inum)
			break;

		slot = path->slots[0];
		eb = path->nodes[0];
		/* make sure we can use eb after releasing the path */
		if (eb != eb_in)
			eb->refs++;
		btrfs_release_path(path);
		iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);

		name_len = btrfs_inode_ref_name_len(eb, iref);
		name_off = (unsigned long)(iref + 1);

		parent = next_inum;
		--bytes_left;
		if (bytes_left >= 0)
			dest[bytes_left] = '/';
	}

	btrfs_release_path(path);

	if (ret)
		return ERR_PTR(ret);

	return dest + bytes_left;
}

static int do_setxattr(struct btrfs_trans_handle *trans,
		       struct inode *inode, const char *name,
		       const void *value, size_t size, int flags)
{
	struct btrfs_dir_item *di;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	size_t name_len = strlen(name);
	int ret = 0;

	if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
		return -ENOSPC;

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

	/* first lets see if we already have this xattr */
	di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
				strlen(name), -1);
	if (IS_ERR(di)) {
		ret = PTR_ERR(di);
		goto out;
	}

	/* ok we already have this xattr, lets remove it */
	if (di) {
		/* if we want create only exit */
		if (flags & XATTR_CREATE) {
			ret = -EEXIST;
			goto out;
		}

		ret = btrfs_delete_one_dir_name(trans, root, path, di);
		BUG_ON(ret);
		btrfs_release_path(path);

		/* if we don't have a value then we are removing the xattr */
		if (!value)
			goto out;
	} else {
		btrfs_release_path(path);

		if (flags & XATTR_REPLACE) {
			/* we couldn't find the attr to replace */
			ret = -ENODATA;
			goto out;
		}
	}

	/* ok we have to create a completely new xattr */
	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
				      name, name_len, value, size);
	BUG_ON(ret);
out:
	btrfs_free_path(path);
	return ret;
}

int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
			  *root, char *name, int name_len, u64 dir,
			  struct btrfs_key *location, u8 type)
{
	int ret = 0;
	struct btrfs_path path;
	struct btrfs_dir_item *dir_item;
	char *name_ptr;
	struct btrfs_key key;
	u32 data_size;

	key.objectid = dir;
	key.flags = 0;
	btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
	if (name_len == 1 && *name == '.')
		key.offset = 1;
	else if (name_len == 2 && name[0] == '.' && name[1] == '.')
		key.offset = 2;
	else
		ret = btrfs_name_hash(name, name_len, &key.offset);
	BUG_ON(ret);
	btrfs_init_path(&path);
	data_size = sizeof(*dir_item) + name_len;
	dir_item = insert_with_overflow(trans, root, &path, &key, data_size);
	if (!dir_item) {
		ret = -1;
		goto out;
	}
	btrfs_cpu_key_to_disk(&dir_item->location, location);
	btrfs_set_dir_type(dir_item, type);
	btrfs_set_dir_flags(dir_item, 0);
	btrfs_set_dir_name_len(dir_item, name_len);
	name_ptr = (char *)(dir_item + 1);
	memcpy(name_ptr, name, name_len);

	/* FIXME, use some real flag for selecting the extra index */
	if (root == root->fs_info->tree_root)
		goto out;

	btrfs_release_path(root, &path);
	btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
	key.offset = location->objectid;
	dir_item = insert_with_overflow(trans, root, &path, &key, data_size);
	if (!dir_item) {
		ret = -1;
		goto out;
	}
	btrfs_cpu_key_to_disk(&dir_item->location, location);
	btrfs_set_dir_type(dir_item, type);
	btrfs_set_dir_flags(dir_item, 0);
	btrfs_set_dir_name_len(dir_item, name_len);
	name_ptr = (char *)(dir_item + 1);
	memcpy(name_ptr, name, name_len);
out:
	btrfs_release_path(root, &path);
	return ret;
}

int btrfs_read_block_groups(struct btrfs_root *root)
{
	struct btrfs_path path;
	int ret;
	int err = 0;
	struct btrfs_block_group_item *bi;
	struct btrfs_block_group_cache *cache;
	struct btrfs_key key;
	struct btrfs_key found_key;
	struct btrfs_leaf *leaf;
	u64 group_size_blocks = BTRFS_BLOCK_GROUP_SIZE / root->blocksize;

	root = root->fs_info->extent_root;
	key.objectid = 0;
	key.offset = group_size_blocks;
	key.flags = 0;
	btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
	btrfs_init_path(&path);

	while(1) {
		ret = btrfs_search_slot(NULL, root->fs_info->extent_root,
					&key, &path, 0, 0);
		if (ret != 0) {
			err = ret;
			break;
		}
		leaf = &path.nodes[0]->leaf;
		btrfs_disk_key_to_cpu(&found_key,
				      &leaf->items[path.slots[0]].key);
		cache = malloc(sizeof(*cache));
		if (!cache) {
			err = -1;
			break;
		}
		bi = btrfs_item_ptr(leaf, path.slots[0],
				    struct btrfs_block_group_item);
		memcpy(&cache->item, bi, sizeof(*bi));
		memcpy(&cache->key, &found_key, sizeof(found_key));
		key.objectid = found_key.objectid + found_key.offset;
		btrfs_release_path(root, &path);
		ret = radix_tree_insert(&root->fs_info->block_group_radix,
					found_key.objectid +
					found_key.offset - 1, (void *)cache);
		BUG_ON(ret);
		if (key.objectid >=
		    btrfs_super_total_blocks(root->fs_info->disk_super))
			break;
	}
	btrfs_release_path(root, &path);
	return 0;
}

/*
 * 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_release_path(root, path);
	btrfs_free_path(path);
	return ret;
}

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 add_new_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)
{
    struct btrfs_root *root = fs_info->free_space_root;
    struct btrfs_free_space_info *info;
    struct btrfs_key key;
    struct extent_buffer *leaf;
    int ret;

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

    ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
    if (ret)
        goto out;

    leaf = path->nodes[0];
    info = btrfs_item_ptr(leaf, path->slots[0],
                          struct btrfs_free_space_info);
    btrfs_set_free_space_extent_count(leaf, info, 0);
    btrfs_set_free_space_flags(leaf, info, 0);
    btrfs_mark_buffer_dirty(leaf);

    ret = 0;
out:
    btrfs_release_path(path);
    return ret;
}

int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
                             struct btrfs_fs_info *fs_info,
                             struct btrfs_block_group_cache *block_group,
                             struct btrfs_path *path, u64 start, u64 size)
{
    struct btrfs_free_space_info *info;
    u32 flags;
    int ret;

    if (block_group->needs_free_space) {
        ret = __add_block_group_free_space(trans, fs_info, block_group,
                                           path);
        if (ret)
            return ret;
    }

    info = search_free_space_info(NULL, fs_info, block_group, path, 0);
    if (IS_ERR(info))
        return PTR_ERR(info);
    flags = btrfs_free_space_flags(path->nodes[0], info);
    btrfs_release_path(path);

    if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
        return modify_free_space_bitmap(trans, fs_info, block_group,
                                        path, start, size, 0);
    } else {
        return add_free_space_extent(trans, fs_info, block_group, path,
                                     start, size);
    }
}

/* 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_release_path(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 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;
}

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_root *btrfs_read_fs_root_no_cache(struct btrfs_fs_info *fs_info,
					       struct btrfs_key *location)
{
	struct btrfs_root *root;
	struct btrfs_root *tree_root = fs_info->tree_root;
	struct btrfs_path *path;
	struct extent_buffer *l;
	u64 generation;
	u32 blocksize;
	int ret = 0;

	root = malloc(sizeof(*root));
	if (!root)
		return ERR_PTR(-ENOMEM);
	memset(root, 0, sizeof(*root));
	if (location->offset == (u64)-1) {
		ret = find_and_setup_root(tree_root, fs_info,
					  location->objectid, root);
		if (ret) {
			free(root);
			return ERR_PTR(ret);
		}
		goto insert;
	}

	__setup_root(tree_root->nodesize, tree_root->leafsize,
		     tree_root->sectorsize, tree_root->stripesize,
		     root, fs_info, location->objectid);

	path = btrfs_alloc_path();
	BUG_ON(!path);
	ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
	if (ret != 0) {
		if (ret > 0)
			ret = -ENOENT;
		goto out;
	}
	l = path->nodes[0];
	read_extent_buffer(l, &root->root_item,
	       btrfs_item_ptr_offset(l, path->slots[0]),
	       sizeof(root->root_item));
	memcpy(&root->root_key, location, sizeof(*location));
	ret = 0;
out:
	btrfs_release_path(root, path);
	btrfs_free_path(path);
	if (ret) {
		free(root);
		return ERR_PTR(ret);
	}
	generation = btrfs_root_generation(&root->root_item);
	blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
	root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
				     blocksize, generation);
	BUG_ON(!root->node);
insert:
	root->ref_cows = 1;
	return root;
}

/*
 * remove an extent from the root, returns 0 on success
 */
static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
			 *root, u64 blocknr, u64 num_blocks, int pin)
{
	struct btrfs_path path;
	struct btrfs_key key;
	struct btrfs_fs_info *info = root->fs_info;
	struct btrfs_root *extent_root = info->extent_root;
	int ret;
	struct btrfs_extent_item *ei;
	struct btrfs_key ins;
	u32 refs;

	BUG_ON(pin && num_blocks != 1);
	key.objectid = blocknr;
	key.flags = 0;
	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
	key.offset = num_blocks;

	find_free_extent(trans, root, 0, 0, (u64)-1, &ins);
	btrfs_init_path(&path);
	ret = btrfs_search_slot(trans, extent_root, &key, &path, -1, 1);
	if (ret) {
		btrfs_print_tree(extent_root, extent_root->node);
		printf("failed to find %llu\n",
		       (u64)key.objectid);
		BUG();
	}
	ei = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0],
			    struct btrfs_extent_item);
	BUG_ON(ei->refs == 0);
	refs = btrfs_extent_refs(ei) - 1;
	btrfs_set_extent_refs(ei, refs);
	if (refs == 0) {
		u64 super_blocks_used;
		if (pin) {
			int err;
			unsigned long bl = blocknr;
			radix_tree_preload(GFP_KERNEL);
			err = radix_tree_insert(&info->pinned_radix,
						blocknr, (void *)bl);
			BUG_ON(err);
			radix_tree_preload_end();
		}
		super_blocks_used = btrfs_super_blocks_used(info->disk_super);
		btrfs_set_super_blocks_used(info->disk_super,
					    super_blocks_used - num_blocks);
		ret = btrfs_del_item(trans, extent_root, &path);
		if (!pin && extent_root->fs_info->last_insert.objectid >
		    blocknr)
			extent_root->fs_info->last_insert.objectid = blocknr;
		if (ret)
			BUG();
		ret = update_block_group(trans, root, blocknr, num_blocks, 0);
		BUG_ON(ret);
	}
	btrfs_release_path(extent_root, &path);
	finish_current_insert(trans, extent_root);
	return ret;
}