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From: David Sterba <dsterba@suse.cz>
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 v2 0/2] Use exclusive lock for file_remove_privs
Date: Tue, 5 Sep 2023 20:02:59 +0200	[thread overview]
Message-ID: <20230905180259.GG14420@twin.jikos.cz> (raw)
In-Reply-To: <20230831112431.2998368-1-bschubert@ddn.com>

On Thu, Aug 31, 2023 at 01:24:29PM +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.
> 
> Note: Compilation tested only.

The fix makes sense, there should be no noticeable performance impact,
basically the same check is done in the newly exported helper for the
IS_NOSEC bit.  I can give it a test locally for the default case, I'm
not sure if we have specific tests for the security layers in fstests.

Regarding merge, I can take the two patches via btrfs tree or can wait
until the export is present in Linus' tree in case FUSE needs it
independently.

  parent reply	other threads:[~2023-09-05 18:16 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-31 11:24 [PATCH v2 0/2] Use exclusive lock for file_remove_privs Bernd Schubert
2023-08-31 11:24 ` [PATCH 1/2] fs: Add and export file_needs_remove_privs Bernd Schubert
2023-08-31 13:16   ` Christian Brauner
2023-08-31 13:40   ` Christian Brauner
2023-08-31 14:17     ` Bernd Schubert
2023-09-01 12:50       ` Christian Brauner
2023-08-31 11:24 ` [PATCH 2/2] btrfs: file_remove_privs needs an exclusive lock Bernd Schubert
2023-09-05 18:02 ` David Sterba [this message]
2023-09-06 14:43   ` [PATCH v2 0/2] Use exclusive lock for file_remove_privs Christian Brauner
2023-09-06 14:51     ` Bernd Schubert
2023-09-06 15:07       ` Christian Brauner
2023-09-07 14:00     ` David Sterba

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