From: David Howells <dhowells@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: dhowells@redhat.com, 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, 04 Mar 2026 14:21:54 +0000 [thread overview]
Message-ID: <114166.1772634114@warthog.procyon.org.uk> (raw)
In-Reply-To: <aag8fPUDCY_g-_LY@infradead.org>
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?
(Before you ask, yes, I do want to keep track of this myself, but working out
the best way to do that without reinventing the filesystem is the issue -
well, that and finding time to do it).
David
next prev parent reply other threads:[~2026-03-04 14:22 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 [this message]
2026-03-04 14:25 ` Christoph Hellwig
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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