linux-kernel - Re: [PATCH v2 1/2] block: add sync_blockdev

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Message-ID: <Yk6cnX5eHrJYrVXQ@infradead.org>
Date:   Thu, 7 Apr 2022 01:11:09 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     "Yuezhang.Mo@...y.com" <Yuezhang.Mo@...y.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Namjae Jeon <linkinjeon@...nel.org>,
        "sj1557.seo@...sung.com" <sj1557.seo@...sung.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "Andy.Wu@...y.com" <Andy.Wu@...y.com>,
        "Wataru.Aoyama@...y.com" <Wataru.Aoyama@...y.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>
Subject: Re: [PATCH v2 1/2] block: add sync_blockdev_range()

On Wed, Apr 06, 2022 at 10:21:15AM +0000, Yuezhang.Mo@...y.com wrote:
> > From: Christoph Hellwig <hch@...radead.org>
> > > --- a/block/bdev.c
> > > +++ b/block/bdev.c
> > > @@ -200,6 +200,16 @@ int sync_blockdev(struct block_device *bdev)  }
> > > EXPORT_SYMBOL(sync_blockdev);
> > >
> > > +int sync_blockdev_range(struct block_device *bdev, loff_t lstart,
> > > +loff_t lend) {
> > > +	if (!bdev)
> > > +		return 0;
> > 
> > This check isn't really needed, and I don't think we need a !CONFIG_BLOCK
> > stub for this either.
> 
> sync_blockdev() and related helpers have this check and a !CONFIG_BLOCK stub.
> I would like to understand the background of your comment, could you explain a little more?

sync_blockdev and sync_blockdev do that because they are unconditionally
called from sync_filesystem, and not just from block-dependent code.
Eventually that should be cleaned up as well, but please don't add it to
new code.