On Wed, Dec 05, 2018 at 12:04:16PM +0100, Jan Kara wrote: > Hi Jerome! > > On Mon 03-12-18 15:18:16, jglisse@xxxxxxxxxx wrote: > > From: Jérôme Glisse <jglisse@xxxxxxxxxx> > > > > To avoid having to change many call sites everytime we want to add a > > parameter use a structure to group all parameters for the mmu_notifier > > invalidate_range_start/end cakks. No functional changes with this > > patch. > > Two suggestions for the patch below: > > > @@ -772,7 +775,8 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index, > > * call mmu_notifier_invalidate_range_start() on our behalf > > * before taking any lock. > > */ > > - if (follow_pte_pmd(vma->vm_mm, address, &start, &end, &ptep, &pmdp, &ptl)) > > + if (follow_pte_pmd(vma->vm_mm, address, &range, > > + &ptep, &pmdp, &ptl)) > > continue; > > The change of follow_pte_pmd() arguments looks unexpected. Why should that > care about mmu notifier range? I see it may be convenient but it doesn't look > like a good API to me. Saddly i do not see a way around that one this is because of fs/dax.c which does the mmu_notifier_invalidate_range_end while follow_pte_pmd do the mmu_notifier_invalidate_range_start follow_pte_pmd does adjust the start and end address so that the dax function does not have the logic to find those address. So instead of duplicating that follow_pte_pmd inside the dax code i rather passed around the range struct to follow_pte_pmd. > > > @@ -1139,11 +1140,15 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, > > downgrade_write(&mm->mmap_sem); > > break; > > } > > - mmu_notifier_invalidate_range_start(mm, 0, -1); > > + > > + range.start = 0; > > + range.end = -1UL; > > + range.mm = mm; > > + mmu_notifier_invalidate_range_start(&range); > > Also how about providing initializer for struct mmu_notifier_range? Or > something like DECLARE_MMU_NOTIFIER_RANGE? That will make sure that > unused arguments for particular notification places have defined values and > also if you add another mandatory argument (like you do in your third > patch), you just add another argument to the initializer and that way > the compiler makes sure you haven't missed any place. Finally the code will > remain more compact that way (less lines needed to initialize the struct). That is what i do in v2 :) Thank you for looking to all this. Cheers, Jérôme
