Re: [PATCH 04/12] xfs: initialize ioma->flags in xfs_bmbt_to_iomap

From: Christoph Hellwig
Date: Tue Jun 25 2019 - 06:07:33 EST

On Mon, Jun 24, 2019 at 07:57:07AM -0700, Darrick J. Wong wrote:
> On Mon, Jun 24, 2019 at 07:52:45AM +0200, Christoph Hellwig wrote:
> > Currently we don't overwrite the flags field in the iomap in
> > xfs_bmbt_to_iomap. This works fine with 0-initialized iomaps on stack,
> > but is harmful once we want to be able to reuse an iomap in the
> > writeback code.
> Is that going to affect all the other iomap users, or is xfs the only
> one that assumes zero-initialized iomaps being passed into
> ->iomap_begin?

This doesn't affect any existing user as they all get a zeroed iomap
passed from the caller in iomap.c. It affects the writeback code
once it uses struct iomap as it overwrites a previously used iomap.