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Date:   Wed, 25 Nov 2020 17:22:50 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Jan Kara <jack@suse.cz>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        Tejun Heo <tj@kernel.org>, Josef Bacik <josef@toxicpanda.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Johannes Thumshirn <johannes.thumshirn@wdc.com>,
        dm-devel@redhat.com, Richard Weinberger <richard@nod.at>,
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Subject: Re: [PATCH 04/45] fs: simplify freeze_bdev/thaw_bdev
Message-ID: <20201125162250.GA795@lst.de>
References: <20201124132751.3747337-1-hch@lst.de> <20201124132751.3747337-5-hch@lst.de> <20201125122953.GH16944@quack2.suse.cz>
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On Wed, Nov 25, 2020 at 01:29:53PM +0100, Jan Kara wrote:
> >  	mutex_unlock(&bdev->bd_fsfreeze_mutex);
> > -	return sb;	/* thaw_bdev releases s->s_umount */
> > +	return error;	/* thaw_bdev releases s->s_umount */
> 
> The comment about thaw_bdev() seems to be stale? At least I don't see what
> it's speaking about...

Yes, this comment seems long stale.  I think in the very early days
we held s_umount on frozen file system, which caused all kinds of
problems.

> >  	mutex_unlock(&bdev->bd_fsfreeze_mutex);
> > -	return error;
> > +	return 0;
> 
> But we now won't return -EINVAL if this gets called e.g. with
> bd_fsfreeze_count == 0, right?

Yes.  I had tried to drop the return value as all the freeze_bdev
calls ignored it.  But I had missed the unpaired emergency thaw and put
it back and messed this up..