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>
Subject: Re: [RFC PATCH 17/17] netfs: Combine prepare and issue ops and grab the buffers on request
Date: Wed, 4 Mar 2026 07:01:00 -0800 [thread overview]
Message-ID: <aahJLBBQuqWNDk6p@infradead.org> (raw)
In-Reply-To: <181470.1772635861@warthog.procyon.org.uk>
On Wed, Mar 04, 2026 at 02:51:01PM +0000, David Howells wrote:
> > > +static int cachefiles_query_occupancy(struct netfs_cache_resources *cres,
> > > + struct fscache_occupancy *occ)
> > > +{
> >
> > Independent of fiemap or not, how is this supposed to work? File
> > systems can create speculative preallocations any time they want,
> > so simply querying for holes vs data will corrupt your cache trivially.
>
> SEEK_DATA and SEEK_HOLE avoid preallocations, I presume?
No, they can't. The file system doesn't even know what range is
a persistent preallocation or not. You need to track your cached
ranges yourself.
next prev parent reply other threads:[~2026-03-04 15:01 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
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 [this message]
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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