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

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Message-ID: <20191009125132.GC5050@quack2.suse.cz>
Date:   Wed, 9 Oct 2019 14:51:32 +0200
From:   Jan Kara <jack@...e.cz>
To:     Matthew Bobrowski <mbobrowski@...browski.org>
Cc:     Jan Kara <jack@...e.cz>, 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 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@...e.com>
SUSE Labs, CR