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Date: Tue, 5 Dec 2023 22:44:30 -0800
From: Eric Biggers <ebiggers@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-btrfs@vger.kernel.org, Josef Bacik <josef@toxicpanda.com>
Subject: Re: [PATCH] fscrypt: move the call to fscrypt_destroy_keyring() into
 ->put_super()
Message-ID: <20231206064430.GA41771@sol.localdomain>
References: <20231206001325.13676-1-ebiggers@kernel.org>
 <ZXAW1BREPtCSUz4W@infradead.org>
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In-Reply-To: <ZXAW1BREPtCSUz4W@infradead.org>

On Tue, Dec 05, 2023 at 10:38:12PM -0800, Christoph Hellwig wrote:
> On Tue, Dec 05, 2023 at 04:13:24PM -0800, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > btrfs, which is planning to add support for fscrypt, has a variety of
> > asynchronous things it does with inodes that can potentially last until
> > ->put_super, when it shuts everything down and cleans up all async work.
> > Consequently, btrfs needs the call to fscrypt_destroy_keyring() to
> > happen either after or within ->put_super.
> > 
> > Meanwhile, f2fs needs the call to fscrypt_destroy_keyring() to happen
> > either *before* or within ->put_super, due to the dependency of
> > f2fs_get_devices() on ->s_fs_info still existing.
> 
> And that means f2fs should free ->s_fs_info in ->kill_sb after
> the call to shutdown_generic_super.
> 
> So the right thing here is:
> 
>  - change f2fs to free ->s_fs_info later
>  - move down fscrypt_destroy_keyring in the keneric code to happen
>    after ->put_super
> 

There are lots of filesystems that free their ->s_fs_info in ->put_super().  Are
they all wrong?

- Eric