[PATCHSET,v24.0,0/6] xfs: detect incorrect gaps in refcount btree

Message

Darrick J. Wong Dec. 30, 2022, 10:11 p.m. UTC

Hi all,

The next few patchsets address a deficiency in scrub that I found while
QAing the refcount btree scrubber.  If there's a gap between refcount
records, we need to cross-reference that gap with the reverse mappings
to ensure that there are no overlapping records in the rmap btree.  If
we find any, then the refcount btree is not consistent.  This is not a
property that is specific to the refcount btree; they all need to have
this sort of keyspace scanning logic to detect inconsistencies.

To do this accurately, we need to be able to scan the keyspace of a
btree (which we already do) to be able to tell the caller if the
keyspace is empty, sparse, or fully covered by records.  The first few
patches add the keyspace scanner to the generic btree code, along with
the ability to mask off parts of btree keys because when we scan the
rmapbt, we only care about space usage, not the owners.

The final patch closes the scanning gap in the refcountbt scanner.

v23.1: create helpers for the key extraction and comparison functions,
       improve documentation, and eliminate the ->mask_key indirect
       calls

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=scrub-detect-refcount-gaps

xfsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=scrub-detect-refcount-gaps
---
 fs/xfs/libxfs/xfs_alloc.c          |   11 +-
 fs/xfs/libxfs/xfs_alloc.h          |    4 -
 fs/xfs/libxfs/xfs_alloc_btree.c    |   28 ++++-
 fs/xfs/libxfs/xfs_bmap_btree.c     |   19 +++
 fs/xfs/libxfs/xfs_btree.c          |  208 ++++++++++++++++++++++++++----------
 fs/xfs/libxfs/xfs_btree.h          |  141 ++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_ialloc_btree.c   |   22 +++-
 fs/xfs/libxfs/xfs_refcount.c       |   11 +-
 fs/xfs/libxfs/xfs_refcount.h       |    4 -
 fs/xfs/libxfs/xfs_refcount_btree.c |   21 +++-
 fs/xfs/libxfs/xfs_rmap.c           |   15 ++-
 fs/xfs/libxfs/xfs_rmap.h           |    4 -
 fs/xfs/libxfs/xfs_rmap_btree.c     |   61 ++++++++---
 fs/xfs/libxfs/xfs_types.h          |   12 ++
 fs/xfs/scrub/agheader.c            |    5 +
 fs/xfs/scrub/alloc.c               |    7 +
 fs/xfs/scrub/bmap.c                |   11 +-
 fs/xfs/scrub/btree.c               |   24 ++--
 fs/xfs/scrub/ialloc.c              |    2 
 fs/xfs/scrub/inode.c               |    1 
 fs/xfs/scrub/refcount.c            |  124 ++++++++++++++++++++-
 fs/xfs/scrub/rmap.c                |    6 +
 fs/xfs/scrub/scrub.h               |    2 
 23 files changed, 612 insertions(+), 131 deletions(-)