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Date: Tue, 12 Aug 2025 12:09:49 -0700
From: "Darrick J. Wong" <djwong@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Andrey Albershteyn <aalbersh@redhat.com>, fsverity@lists.linux.dev,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	david@fromorbit.com, ebiggers@kernel.org
Subject: Re: [PATCH RFC 12/29] fsverity: expose merkle tree geometry to
 callers
Message-ID: <20250812190949.GN7965@frogsfrogsfrogs>
References: <20250728-fsverity-v1-0-9e5443af0e34@kernel.org>
 <20250728-fsverity-v1-12-9e5443af0e34@kernel.org>
 <20250811114813.GC8969@lst.de>
 <20250811153822.GK7965@frogsfrogsfrogs>
 <20250812074208.GB18413@lst.de>
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In-Reply-To: <20250812074208.GB18413@lst.de>

On Tue, Aug 12, 2025 at 09:42:08AM +0200, Christoph Hellwig wrote:
> On Mon, Aug 11, 2025 at 08:38:22AM -0700, Darrick J. Wong wrote:
> > > Just curious, why does xfs need this, but the existing file systems
> > > don't?  That would be some good background information for the commit
> > > message.
> > 
> > Hrmmm... the last time I sent this RFC, online fsck used it to check the
> > validity of the merkle tree xattrs.
> 
> I saw a few users, so it does get used.  But patches exporting something
> should in generaly document what the use case is.
> 
> > > > +	if (!IS_VERITY(inode))
> > > > +		return -ENODATA;
> > > > +
> > > > +	error = ensure_verity_info(inode);
> > > > +	if (error)
> > > > +		return error;
> > > > +
> > > > +	vi = inode->i_verity_info;
> > > 
> > > Wouldn't it be a better interface to return the verity_ino from
> > > ensure_verity_info (NULL for !IS_VERITY, ERR_PTR for real error)
> > > and then just look at the fields directly?
> > 
> > They're private to fsverity_private.h.
> 
> Indeed.  Is ensure_verity_info ven the right thing here?  I.e.
> should quering the paramters create the info if it wasn't there
> yet?

I think it's usually the case that we're about to access the merkle tree
anyway, so the next step in whatever we're doing would load it for us.

--D