Re: [PATCH] ubifs: Add freeze support

From: Hyunchul Lee <hyc.lee@gmail.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Artem Bityutskiy <dedekind1@gmail.com>,
	Richard Weinberger <richard@nod.at>,
	adrian.hunter@intel.com, linux-kernel@vger.kernel.org,
	kernel-team@lge.com, linux-mtd@lists.infradead.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] ubifs: Add freeze support
Date: Mon, 29 May 2017 09:43:46 +0900	[thread overview]
Message-ID: <20170529004346.GA10215@sebu> (raw)
In-Reply-To: <20170527082338.GC32125@infradead.org>

On Sat, May 27, 2017 at 01:23:38AM -0700, Christoph Hellwig wrote:
> > +static int ubifs_freeze_super(struct super_block *sb)
> > +{
> > +	struct ubifs_info *c = sb->s_fs_info;
> > +	int err;
> > +
> > +	dbg_gen("starting");
> > +	/* freeze_super always succeeds if file system is in read-only.
> > +	 * however if there are errors, UBIFS is switched to read-only mode.
> > +	 * so @ro_error should be checked.
> > +	 */
> > +	err = freeze_super(sb);
> > +	if (!err && c->ro_error) {
> > +		thaw_super(sb);
> > +		return -EIO;
> > +	}
> > +	return err;
> 
> This is just broken.  First ubifs should still properly propagate
> the errors, and second freezing/unfreezing read only file systems is
> perfectly valid, 

it is right.

> and third the freeze_super method is a special
> hack for gfs2 that should not gain additional users.

I thought that it was ok. because commit 48b6bca says "every filesystem
that implements this hooks must call the vfs freeze_super ..."

Thank you for comment.
> 
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-- 

Thanks,
Hyunchul