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Date:   Tue, 18 May 2021 08:33:41 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     "bfields@fieldses.org" <bfields@fieldses.org>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Trond Myklebust <trondmy@hammerspace.com>,
        "nickhuang@synology.com" <nickhuang@synology.com>,
        "chuck.lever@oracle.com" <chuck.lever@oracle.com>,
        "robbieko@synology.com" <robbieko@synology.com>,
        "bingjingc@synology.com" <bingjingc@synology.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        viro@zeniv.linux.org.uk
Subject: Re: [PATCH] nfsd: Prevent truncation of an unlinked inode from
 blocking access to its directory
Message-ID: <YKNt1cJn/e0w/ftm@infradead.org>
References: <20210514035829.5230-1-nickhuang@synology.com>
 <00195ec8bf1752306f549540eed74c3938c5e312.camel@hammerspace.com>
 <YJ9yD1S6Yl2m0gOO@infradead.org>
 <20210517185659.GA4216@fieldses.org>
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On Mon, May 17, 2021 at 02:56:59PM -0400, bfields@fieldses.org wrote:
> On Sat, May 15, 2021 at 08:02:39AM +0100, Christoph Hellwig wrote:
> > On Fri, May 14, 2021 at 03:46:57PM +0000, Trond Myklebust wrote:
> > > Why leave the commit_metadata() call under the lock? If you're
> > > concerned about latency, then it makes more sense to call fh_unlock()
> > > before flushing those metadata updates to disk.
> > 
> > Also I'm not sure why the extra inode reference is needed.  What speaks
> > against just moving the dput out of the locked section?
> 
> I don't know.  Do you know why do_unlinkat() is doing the same thing?

No.  Al, any idea why unlink does the final dput under i_rwsem?