linux-ext4 - Re: [PATCH v4 5/8] ext4: move inode extension/truncate code out from ->iomap

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Message-ID: <20191010054418.GD19064@bobrowski>
Date:   Thu, 10 Oct 2019 16:44:18 +1100
From:   Matthew Bobrowski <mbobrowski@...browski.org>
To:     Jan Kara <jack@...e.cz>
Cc:     tytso@....edu, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        hch@...radead.org, david@...morbit.com, darrick.wong@...cle.com
Subject: Re: [PATCH v4 5/8] ext4: move inode extension/truncate code out from
 ->iomap_end() callback

On Wed, Oct 09, 2019 at 02:51:32PM +0200, Jan Kara wrote:
> 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.

Agreed. Well, I think we've got some movement in the right direction in 8/8,
so it looks like changing up the return values is what we'll go ahead with.

--<M>--