From: Christoph Hellwig <hch@infradead.org>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org,
Christian Borntraeger <borntraeger@linux.ibm.com>
Subject: Re: [PATCH RFC v2] btrfs: disable direct reads to avoid dirty folios without fs knowing
Date: Thu, 23 Jul 2026 04:31:37 -0700 [thread overview]
Message-ID: <amH7mUsPFIAJXZUg@infradead.org> (raw)
In-Reply-To: <c6dfdac9fc51c94183e51a861eec269185239660.1784787211.git.wqu@suse.com>
On Thu, Jul 23, 2026 at 03:43:40PM +0930, Qu Wenruo wrote:
> There is a bug report that a reproducer which doing the following
> workloads in two threads:
>
> - Direct read into memory mapped from page cache
> - Sync the above range
>
> This can lead to dirty folios without fs knowing, this can be a huge
> problem for btrfs, as even on the very basic bs == ps cases without
> large folios, such reproducer can screw up the ordered extent accounting
> already:
Disabling direct I/O on btrfs is not going to help you with that,
as you could still call the direct I/O read operation on another
file system (or a block device, or various other direct I/O like
things) on the btrfs file mapping.
prev parent reply other threads:[~2026-07-23 11:31 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <c6dfdac9fc51c94183e51a861eec269185239660.1784787211.git.wqu@suse.com>
2026-07-23 6:48 ` [PATCH RFC v2] btrfs: disable direct reads to avoid dirty folios without fs knowing Christian Borntraeger
2026-07-23 6:59 ` Qu Wenruo
2026-07-23 9:45 ` Help needed to address the dirty folio without fs notification delimma (Re: [PATCH RFC v2] btrfs: disable direct reads to avoid dirty folios without fs knowing) Qu Wenruo
2026-07-23 12:37 ` Matthew Wilcox
2026-07-23 10:38 ` [PATCH RFC v2] btrfs: disable direct reads to avoid dirty folios without fs knowing Filipe Manana
2026-07-23 11:17 ` Qu Wenruo
2026-07-23 11:23 ` Filipe Manana
2026-07-23 11:45 ` Christian Borntraeger
2026-07-23 11:31 ` Christoph Hellwig [this message]
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