Re: [PATCH 14/18] xfs: simplify xfs_reflink_convert_cow

[Christoph Hellwig <hch@lst.de>]

On Tue, Oct 31, 2017 at 03:20:45PM -0700, Darrick J. Wong wrote:
> >  #define XFS_BMAPI_DELALLOC	0x400
> >  
> > +/* Only convert unwritten extents, don't allocate new hotels */
> 
> New ... blocks?

blocks.

> > +#define XFS_BMAPI_CONVERT_ONLY	0x800
> 
> I wonder if this and XFS_BMAPI_DELALLOC could be solved with a single
> flag that means "don't fill in any holes; only touch pre-existing
> extents" ?

Maybe..  My real plan here is to get rid of xfs_bmapi_write in its
current form.  When we convert delalloc to real we never want to allocate
blocks for holes, and in general the loop will look fairly different.

Except for a DAX special case when we convert unwritten extents we never
really want to fill holes.  There is just way to much magic in
xfs_bmapi_write and it would benefit a lot from being split into a three
different functions.

But I'd like to finish one project first before getting into another
big one..

> >  #define XFS_BMAPI_FLAGS \
> >  	{ XFS_BMAPI_ENTIRE,	"ENTIRE" }, \
> >  	{ XFS_BMAPI_METADATA,	"METADATA" }, \
> 
> If you do end up adding a new BMAPI flag, this needs updating so the
> tracepoints keep working.

Fixed.