[0/4] btrfs: detect and fix the ram_bytes mismatch

Message

Qu Wenruo June 25, 2024, 5:07 a.m. UTC

There is a long existing mismatch between ram_bytes and disk_num_bytes
for regular non-compressed data extents.

It turns out to be caused by truncated ordered extents, which modified
ram_bytes unnecessarily.

Thankfully this is not going to cause any data corruption or whatever,
kernel can handle it correctly without any extra problem.
It's only a small violation on the on-disk format.

This series would fix by:

- Cleanup the @bytenr usage inside btrfs_extent_item_to_extent_map()
- Override the ram_bytes when reading file extent items from disk
  So that we always get correct extent maps even if the on-disk one is
  incorrect.
- Add the proper fix for the ram_bytes mismatch
- Add a tree-checker for the ram_bytes mismatch
  Since we can have on-disk ram_bytes incorrect already, this check is
  only for DEBUG and ASSERT builds, and it won't report error but only
  does a kernel warning for us to catch.

Qu Wenruo (4):
  btrfs: cleanup the bytenr usage inside
    btrfs_extent_item_to_extent_map()
  btrfs: make validate_extent_map() to catch ram_bytes mismatch
  btrfs: fix the ram_bytes assignment for truncated ordered extents
  btrfs: tree-checker: add extra ram_bytes and disk_num_bytes check

 fs/btrfs/extent_map.c   |  5 +++++
 fs/btrfs/file-item.c    |  9 ++++-----
 fs/btrfs/inode.c        |  4 +---
 fs/btrfs/tree-checker.c | 19 +++++++++++++++++++
 4 files changed, 29 insertions(+), 8 deletions(-)