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[1/2] design: update metadata reconstruction chapter

Message ID 173092058951.2883036.12931641443859459770.stgit@frogsfrogsfrogs (mailing list archive)
State New
Headers show
Series [1/2] design: update metadata reconstruction chapter | expand

Commit Message

Darrick J. Wong Nov. 6, 2024, 7:18 p.m. UTC 
From: Darrick J. Wong <djwong@kernel.org>

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@kernel.org>
---
 .../reconstruction.asciidoc                        |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

Comments

Christoph Hellwig Nov. 7, 2024, 7:28 a.m. UTC | #1 
Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
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Patch

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.