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Date: Wed, 19 Nov 2025 11:08:00 +0100
From: Christoph Hellwig <hch@lst.de>
To: Dai Ngo <dai.ngo@oracle.com>
Cc: Benjamin Coddington <bcodding@hammerspace.com>,
	Chuck Lever <chuck.lever@oracle.com>, jlayton@kernel.org,
	neilb@ownmail.net, okorniev@redhat.com, tom@talpey.com, hch@lst.de,
	alex.aring@gmail.com, viro@zeniv.linux.org.uk, brauner@kernel.org,
	jack@suse.cz, linux-fsdevel@vger.kernel.org,
	linux-nfs@vger.kernel.org
Subject: Re: [PATCH v4 3/3] FSD: Fix NFS server hang when there are
 multiple layout conflicts
Message-ID: <20251119100800.GB25962@lst.de>
References: <20251115191722.3739234-1-dai.ngo@oracle.com> <20251115191722.3739234-4-dai.ngo@oracle.com> <d7888dd6-c238-45e0-94c0-ac82fb90d6b6@oracle.com> <18135047-8695-4190-b7ca-b7575d9e4c6c@oracle.com> <09209CBD-6BEE-4BCE-8A13-D62F96A5BD87@hammerspace.com> <aeb05ba9-83c5-45a4-a75b-f76fc4686e7c@oracle.com>
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On Mon, Nov 17, 2025 at 02:00:07PM -0800, Dai Ngo wrote:
> Perhaps I overstated the severity of the risk. The real issue is, in the
> current state, SCSI layout recall has no timeout and if there are enough
> activities on the server that results in lots of layout conflicts then the
> server can hang.

All this is really caused by the synchronous waiting.  I'm not against
the workaround here, but I think we need to address that.  There's
really no reason to consumer threads for this waiting activity and
we'll need to stop doing it.