Re: [patch] fs: remove prepare_write/commit_write

[Nick Piggin <npiggin@suse.de>]

On Wed, Sep 24, 2008 at 07:48:19PM -0400, Christoph Hellwig wrote:
> On Thu, Sep 25, 2008 at 01:41:16AM +0200, Nick Piggin wrote:
> > --- linux-2.6.orig/mm/filemap.c
> > +++ linux-2.6/mm/filemap.c
> > @@ -2016,48 +2016,8 @@ int pagecache_write_begin(struct file *f
> >  {
> >  	const struct address_space_operations *aops = mapping->a_ops;
> >  
> > +	return aops->write_begin(file, mapping, pos, len, flags,
> >  							pagep, fsdata);
> >  }
> >  EXPORT_SYMBOL(pagecache_write_begin);
> 
> Please kill pagecache_write_begin/pagecache_write_end, too.

Well.... we *could* have it handle writes for filesystems that don't
implement write_begin/write_end, couldn't we?

 
> >  static ssize_t generic_perform_write(struct file *file,
> >  				struct iov_iter *i, loff_t pos)
> >  {
> > @@ -2481,10 +2253,7 @@ generic_file_buffered_write(struct kiocb
> >  	struct iov_iter i;
> >  
> >  	iov_iter_init(&i, iov, nr_segs, count, written);
> > -	if (a_ops->write_begin)
> > -		status = generic_perform_write(file, &i, pos);
> > -	else
> > -		status = generic_perform_write_2copy(file, &i, pos);
> > +	status = generic_perform_write(file, &i, pos);
> >  
> >  	if (likely(status >= 0)) {
> >  		written += status;
> 
> Can we merge generic_perform_write back into
> generic_file_buffered_write?  generic_file_buffered_write is left as a
> rather useless wrapper after this.

Yeah that makes sense.

 
> > -	->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
> > +	->write_begin(), ->write_end(), ->sync_page() and ->readpage()
> >  may be called from the request handler (/dev/loop).
> 
> This comment can go away, all file I/O done by the loop device now is
> from a kthread.

Feel like sending a patch to kill that now?

Thanks,
Nick