Re: [PATCH v4 10/12] dax: add struct iomap based DAX PMD support

From: Jan Kara
Date: Wed Oct 05 2016 - 01:50:29 EST

On Tue 04-10-16 09:39:48, Ross Zwisler wrote:
> > The gfp_mask that propagates from __do_fault() or do_page_mkwrite() is fine
> > because at that point it is correct. But once we grab filesystem locks
> > which are not reclaim safe, we should update vmf->gfp_mask we pass further
> > down into DAX code to not contain __GFP_FS (that's a bug we apparently have
> > there). And inside DAX code, we definitely are not generally safe to add
> > __GFP_FS to mapping_gfp_mask(). Maybe we'd be better off propagating struct
> > vm_fault into this function, using passed gfp_mask there and make sure
> > callers update gfp_mask as appropriate.
> Yep, that makes sense to me. In reviewing your set it also occurred to me that
> we might want to stick a struct vm_area_struct *vma pointer in the vmf, since
> you always need a vma when you are using a vmf, but we pass them as a pair
> everywhere.

Actually, vma pointer will be in struct vm_fault after my DAX
write-protection series. So once that lands, we can clean up whatever
duplicit function parameters...


Jan Kara <jack@xxxxxxxx>