[PATCH 0/2] btrfs: fix filesystem corruption caused by space cache race

[Omar Sandoval <osandov@osandov.com>]

From: Omar Sandoval <osandov@fb.com>

Hello,

We recently deployed space_cache v2 on a large set of machines to do
some performance comparisons and found a nasty filesystem corruption bug
that was introduced by the fsync transaction optimization in 5.12. It's
much more likely to affect space_cache=v2 and nospace_cache, but since
space_cache=v1 effectively falls back to nospace_cache if there is a
free space inode generation mismatch, space_cache=v1 could also
theoretically be affected. discard/discard=sync also makes the bug much
easier to hit by making the race window larger.

Patch 1 is the fix itself with a lot more details. Patch 2 is a followup
cleanup.

I'm still working on a reproducer, but I wanted to get this fix out
ASAP.

Thanks!

Omar Sandoval (2):
  btrfs: fix space cache corruption and potential double allocations
  btrfs: get rid of block group caching progress logic

 fs/btrfs/block-group.c     | 49 +++++++++++---------------------------
 fs/btrfs/block-group.h     |  5 +---
 fs/btrfs/extent-tree.c     | 39 +++++++-----------------------
 fs/btrfs/free-space-tree.c |  8 -------
 fs/btrfs/transaction.c     | 41 -------------------------------
 fs/btrfs/zoned.c           |  1 -
 6 files changed, 23 insertions(+), 120 deletions(-)

-- 
2.37.2