iomap: teach iomap to read files with fsverity

Obtain fsverity info for folios with file data and fsverity metadata.
Filesystem can pass vi down to ioend and then to fsverity for
verification. This is different from other filesystems ext4, f2fs, btrfs
supporting fsverity, these filesystems don't need fsverity_info for
reading fsverity metadata. While reading merkle tree iomap requires
fsverity info to synthesize hashes for zeroed data block.

fsverity metadata has two kinds of holes - ones in merkle tree and one
after fsverity descriptor.

Merkle tree holes are blocks full of hashes of zeroed data blocks. These
are not stored on the disk but synthesized on the fly. This saves a bit
of space for sparse files. Due to this iomap also need to lookup
fsverity_info for folios with fsverity metadata. ->vi has a hash of the
zeroed data block which will be used to fill the merkle tree block.

The hole past descriptor is interpreted as end of metadata region. As we
don't have EOF here we use this hole as an indication that rest of the
folio is empty. This patch marks rest of the folio beyond fsverity
descriptor as uptodate.

For file data, fsverity needs to verify consistency of the whole file
against the root hash, hashes of holes are included in the merkle tree.
Verify them too.

Issue reading of fsverity merkle tree on the fsverity inodes. This way
metadata will be available at I/O completion time.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Link: https://patch.msgid.link/20260520123722.405752-9-aalbersh@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions