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Date:   Wed, 9 Oct 2019 14:51:32 +0200
From:   Jan Kara <jack@suse.cz>
To:     Matthew Bobrowski <mbobrowski@mbobrowski.org>
Cc:     Jan Kara <jack@suse.cz>, tytso@mit.edu, adilger.kernel@dilger.ca,
        linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        hch@infradead.org, david@fromorbit.com, darrick.wong@oracle.com
Subject: Re: [PATCH v4 5/8] ext4: move inode extension/truncate code out from
 ->iomap_end() callback
Message-ID: <20191009125132.GC5050@quack2.suse.cz>
References: <cover.1570100361.git.mbobrowski@mbobrowski.org>
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 <20191008112512.GH5078@quack2.suse.cz>
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On Wed 09-10-19 21:18:50, Matthew Bobrowski wrote:
> > Just small nits below:
> > 
> > > +static int ext4_handle_inode_extension(struct inode *inode, loff_t offset,
> > > +				       ssize_t written, size_t count)
> > > +{
> > > +	int ret = 0;
> > 
> > I think both the function and callsites may be slightly simpler if you let
> > the function return 'written' or error (not 0 or error). But I'll leave
> > that decision upto you.
> 
> Hm, don't we actually need to return 0 for success cases so that
> iomap_dio_complete() behaves correctly i.e. increments iocb->ki_pos,
> etc?

Correct, iomap_dio_complete() expects 0 on success. So if we keep calling
ext4_handle_inode_extension() from ->end_io handler, we'd need some
specialcasing there and I agree that changing ext4_handle_inode_extension()
return convention isn't then very beneficial. If we stop calling
ext4_handle_inode_extension() from ->end_io handler (patch 8/8 discussion
pending), then the change would be a clear win.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR