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Date:   Mon, 10 Jul 2023 19:28:39 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Chuck Lever III <chuck.lever@oracle.com>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Chuck Lever <cel@kernel.org>
Subject: Re: NFS workload leaves nfsd threads in D state
Message-ID: <20230710172839.GA7190@lst.de>
References: <7A57C7AE-A51A-4254-888B-FE15CA21F9E9@oracle.com> <20230710075634.GA30120@lst.de> <3F16A14B-F854-41CC-A3CA-87C7946FC277@oracle.com> <F610D6B3-876F-4E5D-A3C4-A30F1B81D9B5@oracle.com>
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User-Agent: Mutt/1.5.17 (2007-11-01)
Precedence: bulk

Only found a virtualized AHCI setup so far without much success.  Can
you try this (from Chengming Zhou) in the meantime?

diff --git a/block/blk-flush.c b/block/blk-flush.c
index dba392cf22bec6..5c392a277b9eb2 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -443,7 +443,7 @@ bool blk_insert_flush(struct request *rq)
 		 * the post flush, and then just pass the command on.
 		 */
 		blk_rq_init_flush(rq);
-		rq->flush.seq |= REQ_FSEQ_POSTFLUSH;
+		rq->flush.seq |= REQ_FSEQ_PREFLUSH;
 		spin_lock_irq(&fq->mq_flush_lock);
 		list_move_tail(&rq->flush.list, &fq->flush_data_in_flight);
 		spin_unlock_irq(&fq->mq_flush_lock);