+/*
+ * When handling a synchronous page fault and the inode need a fsync, we can
+ * insert the PTE/PMD into page tables only after that fsync happened. Skip
+ * insertion for now and return the pfn so that caller can insert it after the
+ * fsync is done.
+ */
+static vm_fault_t dax_fault_synchronous_pfnp(pfn_t *pfnp, pfn_t pfn)
+{
+ if (WARN_ON_ONCE(!pfnp))
+ return VM_FAULT_SIGBUS;
+ *pfnp = pfn;
+ return VM_FAULT_NEEDDSYNC;
+}
+
+static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf,
+ const struct iomap_iter *iter)
+{
+ sector_t sector = dax_iomap_sector(&iter->iomap, iter->pos);
+ unsigned long vaddr = vmf->address;
+ vm_fault_t ret;
+ int error = 0;
+
+ switch (iter->iomap.type) {
+ case IOMAP_HOLE:
+ case IOMAP_UNWRITTEN:
+ clear_user_highpage(vmf->cow_page, vaddr);
+ break;
+ case IOMAP_MAPPED:
+ error = copy_cow_page_dax(iter->iomap.bdev, iter->iomap.dax_dev,
+ sector, vmf->cow_page, vaddr);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ error = -EIO;
+ break;
+ }
+
+ if (error)
+ return dax_fault_return(error);
+
+ __SetPageUptodate(vmf->cow_page);
+ ret = finish_fault(vmf);
+ if (!ret)
+ return VM_FAULT_DONE_COW;
+ return ret;
+}
+
+/**
+ * dax_fault_iter - Common actor to handle pfn insertion in PTE/PMD fault.
+ * @vmf: vm fault instance
+ * @iter: iomap iter
+ * @pfnp: pfn to be returned
+ * @xas: the dax mapping tree of a file
+ * @entry: an unlocked dax entry to be inserted
+ * @pmd: distinguish whether it is a pmd fault
+ */
+static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
+ const struct iomap_iter *iter, pfn_t *pfnp,
+ struct xa_state *xas, void **entry, bool pmd)
+{
+ struct address_space *mapping = vmf->vma->vm_file->f_mapping;
+ const struct iomap *iomap = &iter->iomap;
+ size_t size = pmd ? PMD_SIZE : PAGE_SIZE;
+ loff_t pos = (loff_t)xas->xa_index << PAGE_SHIFT;
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
+ bool sync = dax_fault_is_synchronous(iter->flags, vmf->vma, iomap);
+ unsigned long entry_flags = pmd ? DAX_PMD : 0;
+ int err = 0;
+ pfn_t pfn;
+
+ if (!pmd && vmf->cow_page)
+ return dax_fault_cow_page(vmf, iter);
+
+ /* if we are reading UNWRITTEN and HOLE, return a hole. */
+ if (!write &&
+ (iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) {
+ if (!pmd)
+ return dax_load_hole(xas, mapping, entry, vmf);
+ return dax_pmd_load_hole(xas, vmf, iomap, entry);
+ }
+
+ if (iomap->type != IOMAP_MAPPED) {
+ WARN_ON_ONCE(1);
+ return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
+ }
+
+ err = dax_iomap_pfn(&iter->iomap, pos, size, &pfn);
+ if (err)
+ return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);
+
+ *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, entry_flags,
+ write && !sync);
+
+ if (sync)
+ return dax_fault_synchronous_pfnp(pfnp, pfn);
+
+ /* insert PMD pfn */
+ if (pmd)
+ return vmf_insert_pfn_pmd(vmf, pfn, write);
+
+ /* insert PTE pfn */
+ if (write)
+ return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
+ return vmf_insert_mixed(vmf->vma, vmf->address, pfn);
+}
+