From: Christoph Hellwig <hch@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
Jens Axboe <axboe@kernel.dk>, Leon Romanovsky <leon@kernel.org>,
Christian Brauner <christian@brauner.io>,
Paulo Alcantara <pc@manguebit.com>,
netfs@lists.linux.dev, linux-afs@lists.infradead.org,
linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org,
ceph-devel@vger.kernel.org, v9fs@lists.linux.dev,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Paulo Alcantara <pc@manguebit.org>,
Steve French <sfrench@samba.org>,
Namjae Jeon <linkinjeon@kernel.org>, Tom Talpey <tom@talpey.com>,
Chuck Lever <chuck.lever@oracle.com>
Subject: Re: [RFC PATCH 02/17] vfs: Implement a FIEMAP callback
Date: Wed, 4 Mar 2026 06:25:50 -0800 [thread overview]
Message-ID: <aahA7rQVf5liFYMv@infradead.org> (raw)
In-Reply-To: <114166.1772634114@warthog.procyon.org.uk>
On Wed, Mar 04, 2026 at 02:21:54PM +0000, David Howells wrote:
> Christoph Hellwig <hch@infradead.org> wrote:
>
> > On Wed, Mar 04, 2026 at 02:03:09PM +0000, David Howells wrote:
> > > Implement a callback in the internal kernel FIEMAP API so that kernel users
> > > can make use of it as the filler function expects to write to userspace.
> > > This allows the FIEMAP data to be captured and parsed. This is useful for
> > > cachefiles and also potentially for knfsd and ksmbd to implement their
> > > equivalents of FIEMAP remotely rather than using SEEK_DATA/SEEK_HOLE.
> >
> > Hell no. FIEMAP is purely a debugging toool and must not get anywhere
> > near a data path. NAK to all of this.
>
> So I have to stick with SEEK_DATA/SEEK_HOLE for this?
Yes. Why do you even want to move away from that? It's the far
better API. Of course like all other reporting APIs it still is
racy, but has far less problems than fiemap.
next prev parent reply other threads:[~2026-03-04 14:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-04 14:03 [RFC PATCH 00/17] netfs: [WIP] Keep track of folios in a segmented bio_vec[] chain David Howells
2026-03-04 14:03 ` [RFC PATCH 01/17] netfs: Fix unbuffered/DIO writes to dispatch subrequests in strict sequence David Howells
2026-03-04 14:03 ` [RFC PATCH 02/17] vfs: Implement a FIEMAP callback David Howells
2026-03-04 14:06 ` Christoph Hellwig
2026-03-04 14:21 ` David Howells
2026-03-04 14:25 ` Christoph Hellwig [this message]
2026-03-04 14:34 ` David Howells
2026-03-04 14:03 ` [RFC PATCH 03/17] iov_iter: Add a segmented queue of bio_vec[] David Howells
2026-03-04 14:03 ` [RFC PATCH 04/17] Add a function to kmap one page of a multipage bio_vec David Howells
2026-03-04 14:03 ` [RFC PATCH 05/17] netfs: Add some tools for managing bvecq chains David Howells
2026-03-04 14:03 ` [RFC PATCH 06/17] afs: Use a bvecq to hold dir content rather than folioq David Howells
2026-03-04 14:03 ` [RFC PATCH 07/17] netfs: Add a function to extract from an iter into a bvecq David Howells
2026-03-04 14:03 ` [RFC PATCH 08/17] cifs: Use a bvecq for buffering instead of a folioq David Howells
2026-03-04 14:03 ` [RFC PATCH 09/17] cifs: Support ITER_BVECQ in smb_extract_iter_to_rdma() David Howells
2026-03-04 14:03 ` [RFC PATCH 10/17] netfs: Switch to using bvecq rather than folio_queue and rolling_buffer David Howells
2026-03-04 14:03 ` [RFC PATCH 11/17] cifs: Remove support for ITER_KVEC/BVEC/FOLIOQ from smb_extract_iter_to_rdma() David Howells
2026-03-04 14:03 ` [RFC PATCH 12/17] netfs: Remove netfs_alloc/free_folioq_buffer() David Howells
2026-03-04 14:03 ` [RFC PATCH 13/17] netfs: Remove netfs_extract_user_iter() David Howells
2026-03-04 14:03 ` [RFC PATCH 14/17] iov_iter: Remove ITER_FOLIOQ David Howells
2026-03-04 14:03 ` [RFC PATCH 15/17] netfs: Remove folio_queue and rolling_buffer David Howells
2026-03-04 14:03 ` [RFC PATCH 16/17] netfs: Check for too much data being read David Howells
2026-03-04 14:03 ` [RFC PATCH 17/17] netfs: Combine prepare and issue ops and grab the buffers on request David Howells
2026-03-04 14:39 ` Christoph Hellwig
2026-03-04 14:51 ` David Howells
2026-03-04 15:01 ` Christoph Hellwig
2026-03-23 18:37 ` ChenXiaoSong
2026-03-23 20:14 ` David Howells
2026-03-23 22:44 ` Paulo Alcantara
2026-03-24 1:03 ` ChenXiaoSong
2026-03-24 7:16 ` David Howells
2026-03-24 7:38 ` ChenXiaoSong
2026-03-24 7:53 ` David Howells
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