Changes for Linux 5.1:
- Fix online fsck to handle inode btrees correctly on 64k block
  filesystems.
- Teach online fsck to check directory and attribute names for invalid
  characters.
- Miscellanous fixes for online fsck.
- Introduce a new panic mask so that we can halt immediately on
  metadata corruption (for debugging purposes)
- Fix a block mapping race during writeback.
- Cache unlinked inode list backrefs in memory to speed up list
  processing.
- Separate the bnobt/cntbt and inobt/finobt buffer verifiers so that we
  can detect crosslinked btrees.
- Refactor magic number verification so that we can standardize it.
- Strengthen ondisk metadata structure offset build time verification.
xfs: compile time offset checks for common v4/v5 metadata

The v5 superblock format added various metadata fields (such as crc,
metadata lsn, owner uuid, etc.) to v4 metadata headers or created
new v5 headers for blocks where no such headers existed on v4. Where
v4 headers did exist, the v5 structures are careful to place v4
metadata at the original location. For example, the magic value is
expected to be at the same location in certain blocks to facilitate
version detection.

While failure of this invariant is likely to cause severe and
obvious problems at runtime, we can detect this condition at compile
time via the more recently added on-disk format check
infrastructure. Since there is no runtime cost, add some offset
checks that start with v5 structure definitions, traverse down to
the first bit of common metadata with v4 and ensure that common
metadata is at the expected offset. Note that we don't care about
blocks which had no v4 header because there is no common metadata in
those cases. No functional changes.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
1 file changed