Commit bd3c685e authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: Document __btrfs_inc_extent_ref 



Here is a doc-only patch which tires to deobfuscate the terra-incognita
that arguments for delayed refs are.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 9bebe665

fs/btrfs/extent-tree.c

+34 −0
Original line number Diff line number Diff line
@@ -2207,6 +2207,40 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans, 
	return ret;

}



/*

 * __btrfs_inc_extent_ref - insert backreference for a given extent

 *

 * @trans:	    Handle of transaction

 *

 * @node:	    The delayed ref node used to get the bytenr/length for

 *		    extent whose references are incremented.

 *

 * @parent:	    If this is a shared extent (BTRFS_SHARED_DATA_REF_KEY/

 *		    BTRFS_SHARED_BLOCK_REF_KEY) then it holds the logical

 *		    bytenr of the parent block. Since new extents are always

 *		    created with indirect references, this will only be the case

 *		    when relocating a shared extent. In that case, root_objectid

 *		    will be BTRFS_TREE_RELOC_OBJECTID. Otheriwse, parent must

 *		    be 0

 *

 * @root_objectid:  The id of the root where this modification has originated,

 *		    this can be either one of the well-known metadata trees or

 *		    the subvolume id which references this extent.

 *

 * @owner:	    For data extents it is the inode number of the owning file.

 *		    For metadata extents this parameter holds the level in the

 *		    tree of the extent.

 *

 * @offset:	    For metadata extents the offset is ignored and is currently

 *		    always passed as 0. For data extents it is the fileoffset

 *		    this extent belongs to.

 *

 * @refs_to_add     Number of references to add

 *

 * @extent_op       Pointer to a structure, holding information necessary when

 *                  updating a tree block's flags

 *

 */

static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,

				  struct btrfs_fs_info *fs_info,

				  struct btrfs_delayed_ref_node *node,