linux-kernel - Re: [PATCH] ecryptfs: Fix inodes not being evicted until unmount

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Message-ID: <20210202152255.GA3383@jeffrey-work-20.04>
Date:   Tue, 2 Feb 2021 09:22:55 -0600
From:   Jeffrey Mitchell <jeffrey.mitchell@...rlab.io>
To:     Tyler Hicks <code@...icks.com>
Cc:     ecryptfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dan Robertson <daniel.robertson@...rlab.io>
Subject: Re: [PATCH] ecryptfs: Fix inodes not being evicted until unmount

On Sat, Jan 30, 2021 at 11:06:40AM -0600, Tyler Hicks wrote:
> Hey Jeffrey and Dan - thanks for the patch! Unfortunately, I think this
> would allow the eCryptfs inode's nlink count to get out of sync with the
> lower inode's nlink count in the case of direct manipulation to the
> lower filesystem.

Hmm. What if I instead synchronize it before calling vfs_unlink(), then
call drop_nlink() if vfs_unlink() succeeds?

> Is the condition that you're trying to fix a result of going through the
> this code path?
> 
>  ecryptfs_unlink() -> ecryptfs_do_unlink() -> vfs_unlink() -> nfs_unlink() -> nfs_sillyrename() -> nfs_async_unlink()

Yes, that is the code path that causes it.

V/R,
Jeffrey Mitchell