Re: [PATCH] xfs: fix BUG_ON in xfs_getbmap()

[Darrick J. Wong]

On Mon, Mar 27, 2023 at 06:47:54PM -0700, Christoph Hellwig wrote:
> On Mon, Mar 27, 2023 at 06:43:28PM -0700, Darrick J. Wong wrote:
> > <shrug> Seeing as the data fork mappings can change the instant the
> > ILOCK drops, I'm not /that/ worried about users seeing a delalloc
> > mapping even if the user requested a flush.  The results are already
> > obsolete when they get to userspace, unless the application software has
> > found another means to lock out access to the file.
> 
> That is true, but then again the users asked to not see delalloc
> mappings, so we really shouldn't report one, right?

Yeah, I suppose so.  I wonder how many programs there are out there that
don't pass in BMV_IF_DELALLOC /and/ can't handle that?  But I suppose
taking MMAP_EXCL is good enough to shut up the obvious assertion vector.

The COW implementation probably ought to be doing the flush too.

--D