From: Christoph Hellwig <hch@infradead.org>
To: Bernd Schubert <bschubert@ddn.com>
Cc: linux-fsdevel@vger.kernel.org, bernd.schubert@fastmail.fm,
miklos@szeredi.hu, dsingh@ddn.com,
Josef Bacik <josef@toxicpanda.com>,
linux-btrfs@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>
Subject: Re: [PATCH 0/2] Use exclusive lock for file_remove_privs
Date: Thu, 31 Aug 2023 00:40:45 -0700 [thread overview]
Message-ID: <ZPBD/X9IUrz46Sia@infradead.org> (raw)
In-Reply-To: <20230830181519.2964941-1-bschubert@ddn.com>
On Wed, Aug 30, 2023 at 08:15:17PM +0200, Bernd Schubert wrote:
> While adding shared direct IO write locks to fuse Miklos noticed
> that file_remove_privs() needs an exclusive lock. I then
> noticed that btrfs actually has the same issue as I had in my patch,
> it was calling into that function with a shared lock.
> This series adds a new exported function file_needs_remove_privs(),
> which used by the follow up btrfs patch and will be used by the
> DIO code path in fuse as well. If that function returns any mask
> the shared lock needs to be dropped and replaced by the exclusive
> variant.
FYI, xfs and ext4 use a simple IS_NOSEC check for this. That has
a lot more false positives, but also is a much faster check in the
fast path. It might be worth benchmarking which way to go, but
we should be consistent across file systems for the behavior.
next prev parent reply other threads:[~2023-08-31 7:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-30 18:15 [PATCH 0/2] Use exclusive lock for file_remove_privs Bernd Schubert
2023-08-30 18:15 ` [PATCH 1/2] fs: Add and export file_needs_remove_privs Bernd Schubert
2023-09-01 6:48 ` Christoph Hellwig
2023-08-30 18:15 ` [PATCH 2/2] btrfs: file_remove_privs needs an exclusive lock Bernd Schubert
2023-08-31 7:40 ` Christoph Hellwig [this message]
2023-08-31 10:17 ` [PATCH 0/2] Use exclusive lock for file_remove_privs Bernd Schubert
2023-08-31 10:18 ` Mateusz Guzik
2023-08-31 14:41 ` Bernd Schubert
2023-09-01 6:49 ` Christoph Hellwig
2023-09-01 11:38 ` Matthew Wilcox
2023-09-01 11:47 ` Mateusz Guzik
2023-09-06 15:13 ` Matthew Wilcox
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