btrfs: backref: implement btrfs_backref_iter_next() (c39c2ddc) · Commits · 戴 / test

fs/btrfs/backref.c

+60 −0

Original line number	Diff line number	Diff line
		@@ -2405,3 +2405,63 @@ release:
		btrfs_backref_iter_release(iter);
		return ret;
		}

		/*
		* Go to the next backref item of current bytenr, can be either inlined or
		* keyed.
		*
		* Caller needs to check whether it's inline ref or not by iter->cur_key.
		*
		* Return 0 if we get next backref without problem.
		* Return >0 if there is no extra backref for this bytenr.
		* Return <0 if there is something wrong happened.
		*/
		int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
		{
		struct extent_buffer *eb = btrfs_backref_get_eb(iter);
		struct btrfs_path *path = iter->path;
		struct btrfs_extent_inline_ref *iref;
		int ret;
		u32 size;

		if (btrfs_backref_iter_is_inline_ref(iter)) {
		/* We're still inside the inline refs */
		ASSERT(iter->cur_ptr < iter->end_ptr);

		if (btrfs_backref_has_tree_block_info(iter)) {
		/* First tree block info */
		size = sizeof(struct btrfs_tree_block_info);
		} else {
		/* Use inline ref type to determine the size */
		int type;

		iref = (struct btrfs_extent_inline_ref *)
		((unsigned long)iter->cur_ptr);
		type = btrfs_extent_inline_ref_type(eb, iref);

		size = btrfs_extent_inline_ref_size(type);
		}
		iter->cur_ptr += size;
		if (iter->cur_ptr < iter->end_ptr)
		return 0;

		/* All inline items iterated, fall through */
		}

		/* We're at keyed items, there is no inline item, go to the next one */
		ret = btrfs_next_item(iter->fs_info->extent_root, iter->path);
		if (ret)
		return ret;

		btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]);
		if (iter->cur_key.objectid != iter->bytenr \|\|
		(iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
		iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
		return 1;
		iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
		path->slots[0]);
		iter->cur_ptr = iter->item_ptr;
		iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size_nr(path->nodes[0],
		path->slots[0]);
		return 0;
		}

fs/btrfs/backref.h

+34 −0

Original line number	Diff line number	Diff line
		@@ -104,8 +104,42 @@ static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter)
		kfree(iter);
		}

		static inline struct extent_buffer *btrfs_backref_get_eb(
		struct btrfs_backref_iter *iter)
		{
		if (!iter)
		return NULL;
		return iter->path->nodes[0];
		}

		/*
		* For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data
		* is btrfs_tree_block_info, without a btrfs_extent_inline_ref header.
		*
		* This helper determines if that's the case.
		*/
		static inline bool btrfs_backref_has_tree_block_info(
		struct btrfs_backref_iter *iter)
		{
		if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY &&
		iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item))
		return true;
		return false;
		}

		int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr);

		int btrfs_backref_iter_next(struct btrfs_backref_iter *iter);

		static inline bool btrfs_backref_iter_is_inline_ref(
		struct btrfs_backref_iter *iter)
		{
		if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY \|\|
		iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
		return true;
		return false;
		}

		static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
		{
		iter->bytenr = 0;

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