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Date: Tue, 25 Jun 2019 12:12:50 +0200
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 06/12] xfs: remove XFS_TRANS_NOFS
Message-ID: <20190625101250.GJ1462@lst.de>
References: <20190624055253.31183-1-hch@lst.de> <20190624055253.31183-7-hch@lst.de> <20190624225904.GB7777@dread.disaster.area>
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To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>, "Darrick J . Wong" <darrick.wong@oracle.com>, Damien Le Moal <Damien.LeMoal@wdc.com>, Andreas Gruenbacher <agruenba@redhat.com>, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org

On Tue, Jun 25, 2019 at 08:59:04AM +1000, Dave Chinner wrote:
> On Mon, Jun 24, 2019 at 07:52:47AM +0200, Christoph Hellwig wrote:
> > Instead of a magic flag for xfs_trans_alloc, just ensure all callers
> > that can't relclaim through the file system use memalloc_nofs_save to
> > set the per-task nofs flag.
> 
> I'm thinking that it would be a good idea to add comments to explain
> exactly what the memalloc_nofs_save/restore() are protecting where
> they are used. Right now the XFS_TRANS_NOFS flag is largely
> undocumented, so a reader is left guessing as to why the flag is
> necessary and what contexts it may apply to. Hence I think we should
> fix that while we are changing over to a different GFP_NOFS
> allocation context mechanism....

Sure.