From: Darrick J. Wong <djwong@xxxxxxxxxx> We've landed online repair and full backrefs in the filesystem, so update the links to the new sections and transform future tense to present tense. Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> --- .../reconstruction.asciidoc | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/design/XFS_Filesystem_Structure/reconstruction.asciidoc b/design/XFS_Filesystem_Structure/reconstruction.asciidoc index f172e0f8161656..f4c10217910b6c 100644 --- a/design/XFS_Filesystem_Structure/reconstruction.asciidoc +++ b/design/XFS_Filesystem_Structure/reconstruction.asciidoc @@ -1,10 +1,6 @@ [[Reconstruction]] = Metadata Reconstruction -[NOTE] -This is a theoretical discussion of how reconstruction could work; none of this -is implemented as of 2015. - A simple UNIX filesystem can be thought of in terms of a directed acyclic graph. To a first approximation, there exists a root directory node, which points to other nodes. Those other nodes can themselves be directories or they can be @@ -45,9 +41,14 @@ The xref:Reverse_Mapping_Btree[reverse-mapping B+tree] fills in part of the puzzle. Since it contains copies of every entry in each inode’s data and attribute forks, we can fix a corrupted block map with these records. Furthermore, if the inode B+trees become corrupt, it is possible to visit all -inode chunks using the reverse-mapping data. Should XFS ever gain the ability -to store parent directory information in each inode, it also becomes possible +inode chunks using the reverse-mapping data. xref:Parent_Pointers[Directory +parent pointers] fill in the rest of the puzzle by mirroring the directory tree +structure with parent directory information in each inode. It is now possible to resurrect damaged directory trees, which should reduce the complaints about inodes ending up in +/lost+found+. Everything else in the per-AG primary -metadata can already be reconstructed via +xfs_repair+. Hopefully, -reconstruction will not turn out to be a fool's errand. +metadata can already be reconstructed via +xfs_repair+. + +See the +https://docs.kernel.org/filesystems/xfs/xfs-online-fsck-design.html[design +document] for online repair for a more thorough discussion of how this metadata +are put to use.
