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Date:   Thu, 1 Dec 2022 21:10:15 +0000
From:   Eric Biggers <ebiggers@kernel.org>
To:     xiubli@redhat.com
Cc:     idryomov@gmail.com, ceph-devel@vger.kernel.org, jlayton@kernel.org,
        khiremat@redhat.com, linux-fscrypt@vger.kernel.org
Subject: Re: [PATCH] ceph: make sure all the files successfully put before
 unmounting
Message-ID: <Y4kYN8FPeq6NDe5i@gmail.com>
References: <20221201065800.18149-1-xiubli@redhat.com>
 <Y4j+Ccqzi6JxWchv@sol.localdomain>
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On Thu, Dec 01, 2022 at 11:18:33AM -0800, Eric Biggers wrote:
> On Thu, Dec 01, 2022 at 02:58:00PM +0800, xiubli@redhat.com wrote:
> > From: Xiubo Li <xiubli@redhat.com>
> > 
> > When close a file it will be deferred to call the fput(), which
> > will hold the inode's i_count. And when unmounting the mountpoint
> > the evict_inodes() may skip evicting some inodes.
> > 
> > If encrypt is enabled the kernel generate a warning when removing
> > the encrypt keys when the skipped inodes still hold the keyring:
> 
> This does not make sense.  Unmounting is only possible once all the files on the
> filesystem have been closed.
> 

Specifically, __fput() puts the reference to the dentry (and thus the inode)
*before* it puts the reference to the mount.  And an unmount cannot be done
while the mount still has references.  So there should not be any issue here.

- Eric