[Cluster-devel] [PATCH v4 06/11] iomap: Add write_{begin, end} iomap operations

[Christoph Hellwig <hch@lst.de>]

On Fri, May 25, 2018 at 07:58:14PM +0200, Andreas Gr?nbacher wrote:
> > The right way to deal with that is to make
> > inline data an explicit iomap type (done in my next posting of the
> > buffer head removal series), and then have iomap_begin find the data,
> > kmap it and return it in the iomap, with iomap_end doing any fixups.
> 
> I see what you mean. How would iomap_write_actor deal with
> IOMAP_INLINE -- just skip iomap_write_begin and iomap_write_end and
> grab the page from the iomap?

I would add a data pointer to struct iomap and pass the data back
from there.  We'll still need most of iomap_write_begin / iomap_write_end,
but just copy the data from the iomap instead of reading it from disk.
Note that the block_write_begin code already handles that case for
the get_blocks path.