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Date: Tue, 26 Jul 2022 13:33:33 +0200
From: Christoph Hellwig <hch@lst.de>
To: Guixin Liu <kanie@linux.alibaba.com>
Cc: hch@lst.de, sagi@grimberg.me, kch@nvidia.com,
	linux-nvme@lists.infradead.org
Subject: Re: [PATCH v2] nvmet: avoid unnecessary fsync and flush bio
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On Mon, Jul 25, 2022 at 02:28:18PM +0800, Guixin Liu wrote:
>  u16 nvmet_file_flush(struct nvmet_req *req)
>  {
> -	return errno_to_nvme_status(req, vfs_fsync(req->ns->file, 1));
> +	if (req->ns->buffered_io)
> +		return errno_to_nvme_status(req, vfs_fsync(req->ns->file, 1));
> +	return NVME_SC_SUCCESS;

This is broken.  Even direct I/O needs an fsync to commit metadata
changes.