linux-kernel - Re: [PATCH] nvmet: add revalidation support to bdev and file backed namespaces

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Message-ID: <20200403064331.GA23270@lst.de>
Date:   Fri, 3 Apr 2020 08:43:31 +0200
From:   Christoph Hellwig <hch@....de>
To:     Anthony Iliopoulos <ailiop@...e.com>
Cc:     Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
        Chaitanya Kulkarni <chaitanya.kulkarni@....com>,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nvmet: add revalidation support to bdev and file
 backed namespaces

On Thu, Apr 02, 2020 at 09:30:52PM +0200, Anthony Iliopoulos wrote:
> Add support for detecting capacity changes on nvmet blockdev and file
> backed namespaces. This allows for emulating and testing online resizing
> of nvme devices and filesystems on top.
> 
> Signed-off-by: Anthony Iliopoulos <ailiop@...e.com>

I vaguely remember seeing a very similar patch before, is this a repost?

> +void nvmet_bdev_ns_revalidate(struct nvmet_ns *ns)
> +{
> +	loff_t size;
> +
> +	size = i_size_read(ns->bdev->bd_inode);
> +
> +	if (ns->size != size)
> +		ns->size = size;

This can be:

	ns->size = i_size_read(ns->bdev->bd_inode);

> +void nvmet_file_ns_revalidate(struct nvmet_ns *ns)
> +{
> +	struct kstat stat;
> +
> +	if (!ns->file)
> +		return;

Shouldn't this always be non-NULL?

> +
> +	if (vfs_getattr(&ns->file->f_path,
> +			&stat, STATX_SIZE, AT_STATX_FORCE_SYNC))
> +		return;

Use up the full line:

	if (vfs_getattr(&ns->file->f_path, &stat, STATX_SIZE,
			AT_STATX_FORCE_SYNC))

Also shouldn't there be error handling?  If we can't stat the file
the namespace is toast.