Re: [PATCH 13/21] mm: Pass vm_fault structure into do_page_mkwrite()

[Jan Kara <jack@suse.cz>]

On Wed 16-11-16 01:40:23, Kirill A. Shutemov wrote:
> On Fri, Nov 04, 2016 at 05:25:09AM +0100, Jan Kara wrote:
> > We will need more information in the ->page_mkwrite() helper for DAX to
> > be able to fully finish faults there. Pass vm_fault structure to
> > do_page_mkwrite() and use it there so that information propagates
> > properly from upper layers.
> > 
> > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> >  mm/memory.c | 19 +++++++------------
> >  1 file changed, 7 insertions(+), 12 deletions(-)
> > 
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 4da66c984c2c..c89f99c270bc 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -2038,20 +2038,14 @@ static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
> >   *
> >   * We do this without the lock held, so that it can sleep if it needs to.
> >   */
> > -static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
> > -	       unsigned long address)
> > +static int do_page_mkwrite(struct vm_fault *vmf)
> >  {
> > -	struct vm_fault vmf;
> >  	int ret;
> > +	struct page *page = vmf->page;
> >  
> > -	vmf.address = address;
> > -	vmf.pgoff = page->index;
> > -	vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
> > -	vmf.gfp_mask = __get_fault_gfp_mask(vma);
> > -	vmf.page = page;
> > -	vmf.cow_page = NULL;
> > +	vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
> 
> This can be destructive: we loose rest of the flags here. It's probably
> okay in current state of the code, but may be should restore them before
> return from do_page_mkwrite()?

Yeah, probably makes sense as future-proofing. Changed.

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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