Re: [RFC PATCH 10/11] xfs: add fs-verity support

[Dave Chinner <david@fromorbit.com>]

On Tue, Dec 13, 2022 at 11:08:45AM -0800, Eric Biggers wrote:
> On Tue, Dec 13, 2022 at 06:29:34PM +0100, Andrey Albershteyn wrote:
> > 
> > Also add check that block size == PAGE_SIZE as fs-verity doesn't
> > support different sizes yet.
> 
> That's coming with
> https://lore.kernel.org/linux-fsdevel/20221028224539.171818-1-ebiggers@kernel.org/T/#u,
> which I'll be resending soon and I hope to apply for 6.3.
> Review and testing of that patchset, along with its associated xfstests update
> (https://lore.kernel.org/fstests/20221211070704.341481-1-ebiggers@kernel.org/T/#u),
> would be greatly appreciated.
> 
> Note, as proposed there will still be a limit of:
> 
> 	merkle_tree_block_size <= fs_block_size <= page_size

> Hopefully you don't need fs_block_size > page_size or

Yes, we will.

This back on my radar now that folios have settled down. It's
pretty trivial for XFS to do because we already support metadata
block sizes > filesystem block size. Here is an old prototype:

https://lore.kernel.org/linux-xfs/20181107063127.3902-1-david@fromorbit.com/

> merkle_tree_block_size > fs_block_size?

That's also a desirable addition.

XFS is using xattrs to hold merkle tree blocks so the merkle tree
storage is are already independent of the filesystem block size and
page cache limitations. Being able to using 64kB merkle tree blocks
would be really handy for reducing the search depth and overall IO
footprint of really large files.

Cheers,

Dave.

-- 
Dave Chinner
david@fromorbit.com