On 1/18/23 16:21, Christoph Hellwig wrote: > On Sun, Jan 15, 2023 at 09:29:58AM -0800, Darrick J. Wong wrote: >> I don't have any objections to pulling everything except patches 8 and >> 10 for testing this week. > > That would be great. I now have a series to return the ERR_PTR > from __filemap_get_folio which will cause a minor conflict, but > I think that's easy enough for Linux to handle. > >> >> 1. Does zonefs need to revalidate mappings? The mappings are 1:1 so I >> don't think it does, but OTOH zone pointer management might complicate >> that. > > Adding Damien. zonefs has a static mapping of file blocks that never changes and is fully populated up to a file max size from mount. So zonefs is not using the iomap_valid page operation. In fact, zonefs is not even using struct iomap_page_ops. > >> 2. How about porting the writeback iomap validation to use this >> mechanism? (I suspect Dave might already be working on this...) > > What is "this mechanism"? Do you mean the here removed ->iomap_valid > ? writeback calls into ->map_blocks for every block while under the > folio lock, so the validation can (and for XFS currently is) done > in that. Moving it out into a separate method with extra indirect > functiona call overhead and interactions between the methods seems > like a retrograde step to me. > >> 2. Do we need to revalidate mappings for directio writes? I think the >> answer is no (for xfs) because the ->iomap_begin call will allocate >> whatever blocks are needed and truncate/punch/reflink block on the >> iolock while the directio writes are pending, so you'll never end up >> with a stale mapping. > > Yes. -- Damien Le Moal Western Digital Research
