On Mon, Mar 15, 2021 at 04:09:41PM -0700, Eric Biggers wrote:

On Fri, Mar 05, 2021 at 11:26:28AM -0800, Boris Burkov wrote:

quoted

This patchset provides support for fsverity in btrfs.

At a high level, we store the verity descriptor and Merkle tree data
in the file system btree with the file's inode as the objectid, and
direct reads/writes to those items to implement the generic fsverity
interface required by fs/verity/.

The first patch is a preparatory patch which adds a notion of
compat_flags to the btrfs_inode and inode_item in order to allow
enabling verity on a file without making the file system unmountable for
older kernels. (It runs afoul of the leaf corruption check otherwise)

The second patch is the bulk of the fsverity implementation. It
implements the fsverity interface and adds verity checks for the typical
file reading case.

The third patch cleans up the corner cases in readpage, covering inline
extents, preallocated extents, and holes.

The fourth patch handles direct io of a veritied file by falling back to
buffered io.

The fifth patch handles crashes mid-verity enable via orphan items

Can you include information about how this was tested?

Right now, I'm testing it with the btrfs xfstest I added as well as a
one-off script that corrupts regular extent data. I'm still working on
integrating the btrfs specifics with the generic verity xfstests, and
how to test verity+compression without hacks.

Also, fsverity-utils works with btrfs as-is, correct?

As far as I know, yes. I've tested using both the rpm packaged by Fedora
and building from source.

- Eric