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Date:   Mon, 24 Apr 2023 08:22:20 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        Miklos Szeredi <miklos@szeredi.hu>,
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Subject: Re: [PATCH 11/17] iomap: assign current->backing_dev_info in
 iomap_file_buffered_write
Message-ID: <20230424062220.GA10368@lst.de>
References: <20230424054926.26927-1-hch@lst.de> <20230424054926.26927-12-hch@lst.de> <20230424061825.GO360889@frogsfrogsfrogs>
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On Sun, Apr 23, 2023 at 11:18:25PM -0700, Darrick J. Wong wrote:
> > @@ -876,8 +877,11 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
> >  	if (iocb->ki_flags & IOCB_NOWAIT)
> >  		iter.flags |= IOMAP_NOWAIT;
> >  
> > +	current->backing_dev_info = inode_to_bdi(iter.inode);
> 
> Dumb question from me late on a Sunday night, but does the iomap_unshare
> code need to set this too?  Since it works by dirtying pagecache folios
> without actually changing the contents?

A very good question that I have no answer for.  The
current->backing_dev_info mechanism confuses the heck out of me and
appears basically undocumented.