[v20,0/4] xfs: online repair of AG btrees

Message

Darrick J. Wong Oct. 9, 2019, 4:50 p.m. UTC

Hi all,

This is the first part of the twentieth revision of a patchset that
adds to XFS kernel support for online metadata scrubbing and repair.
There aren't any on-disk format changes.

New for this version is a rebase against 5.3-rc6, bulk loading of
btrees, integration with the health reporting subsystem, and the
explicit revalidation of all metadata structures that were rebuilt.

First, create a new data structure that provides an abstraction of a big
memory array by using linked lists.  This is where we store records for
btree reconstruction.  This first implementation is memory inefficient
and consumes a /lot/ of kernel memory, but lays the groundwork for a
later patch in the set to convert the implementation to use a (memfd)
swap file, which enables us to use pageable memory without pounding the
slab cache.

The three patches after that implement reconstruction of the free space
btrees, inode btrees, and reference count btree.  The reverse mapping
btree requires considerably more thought and will be covered later.

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-ag-btrees

xfsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=repair-ag-btrees