Re: [PATCH 5/5] exportfs: support encoding non-decodeable file handles by default

From: Jan Kara <jack@suse.cz>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Jan Kara <jack@suse.cz>, Jeff Layton <jlayton@kernel.org>,
	Chuck Lever <chuck.lever@oracle.com>,
	Christian Brauner <brauner@kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org
Subject: Re: [PATCH 5/5] exportfs: support encoding non-decodeable file handles by default
Date: Mon, 23 Oct 2023 18:33:08 +0200	[thread overview]
Message-ID: <20231023163308.7szzloiuzzc7lnia@quack3> (raw)
In-Reply-To: <CAOQ4uxhiRU2nNnYtuXUaURMCuYjssC9Rn=ORWW=MmVyMD1H6Rg@mail.gmail.com>

On Mon 23-10-23 16:55:40, Amir Goldstein wrote:
> On Wed, Oct 18, 2023 at 1:00 PM Amir Goldstein <amir73il@gmail.com> wrote:
> >
> > AT_HANDLE_FID was added as an API for name_to_handle_at() that request
> > the encoding of a file id, which is not intended to be decoded.
> >
> > This file id is used by fanotify to describe objects in events.
> >
> > So far, overlayfs is the only filesystem that supports encoding
> > non-decodeable file ids, by providing export_operations with an
> > ->encode_fh() method and without a ->decode_fh() method.
> >
> > Add support for encoding non-decodeable file ids to all the filesystems
> > that do not provide export_operations, by encoding a file id of type
> > FILEID_INO64_GEN from { i_ino, i_generation }.
> >
> > A filesystem may that does not support NFS export, can opt-out of
> > encoding non-decodeable file ids for fanotify by defining an empty
> > export_operations struct (i.e. with a NULL ->encode_fh() method).
> >
> > This allows the use of fanotify events with file ids on filesystems
> > like 9p which do not support NFS export to bring fanotify in feature
> > parity with inotify on those filesystems.
> >
> > Note that fanotify also requires that the filesystems report a non-null
> > fsid.  Currently, many simple filesystems that have support for inotify
> > (e.g. debugfs, tracefs, sysfs) report a null fsid, so can still not be
> > used with fanotify in file id reporting mode.
> >
> > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> 
> Hi Jan,
> 
> Did you get a chance to look at this patch?
> I saw your review comments on the rest of the series, so was waiting
> for feedback on this last one before posting v2.

Ah, sorry. I don't have any further comments regarding this patch besides
what Chuck already wrote.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR