[0/2] btrfs: fix btrfs_file_extent_item::ram_bytes of btrfs_split_ordered_extent()

Message

Qu Wenruo April 15, 2024, 11:24 p.m. UTC

During my extent_map members rework, I added a sanity check to make sure
regular non-compressed extent_map would have its disk_num_bytes to match
ram_bytes.

But that extent_map sanity check always fail as we have on-disk file
extent items which has its ram_bytes much larger than the corresponding
disk_num_bytes, even if it's not compressed.

It turns out that, the ram_bytes > disk_num_bytes is caused by
btrfs_split_ordered_extent(), where it doesn't properly update
ram_bytes, resulting it larger than disk_num_bytes.

Thankfully everything is fine, as our code doesn't really bother
ram_bytes for non-compressed regular file extents, so no real damage.

Still I'd like to catch such problem in the future, so add another
tree-checker patch for this case.

And since the invalid ram_bytes is already in the wild for a while, we
do not want to bother the end users to fix their fs for nothing.
So the check is only behind DEBUG builds.

Furthermore, the tree-checker is only to make sure @ram_bytes <
@disk_num_bytes for non-compressed file extents.
As we still have other locations to make @ram_bytes < @disk_num_bytes.

And for btrfs-progs, I'm going to add extra check and repair support
soon.

Qu Wenruo (2):
  btrfs: set correct ram_bytes when splitting ordered extent
  btrfs: tree-checker: add one extra file extent item ram_bytes check

 fs/btrfs/ordered-data.c |  1 +
 fs/btrfs/tree-checker.c | 35 +++++++++++++++++++++++++++++------
 2 files changed, 30 insertions(+), 6 deletions(-)