device-dax: factor out page mapping initialization

Move initialization of page->mapping into a separate helper.

This is in preparation to move the mapping set to be prior to inserting
the page table entry and also for tidying up compound page handling into
one helper.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Joao Martins <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Jane Chu <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Vishal Verma <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 23 insertions, 22 deletions

diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 630de5a795b0..9c87927d4bc2 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -73,6 +73,27 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 	return -1;
 }
 
+static void dax_set_mapping(struct vm_fault *vmf, pfn_t pfn,
+			      unsigned long fault_size)
+{
+	unsigned long i, nr_pages = fault_size / PAGE_SIZE;
+	struct file *filp = vmf->vma->vm_file;
+	pgoff_t pgoff;
+
+	pgoff = linear_page_index(vmf->vma,
+			ALIGN(vmf->address, fault_size));
+
+	for (i = 0; i < nr_pages; i++) {
+		struct page *page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
+
+		if (page->mapping)
+			continue;
+
+		page->mapping = filp->f_mapping;
+		page->index = pgoff + i;
+	}
+}
+
 static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
 				struct vm_fault *vmf, pfn_t *pfn)
 {
@@ -224,28 +245,8 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
 		rc = VM_FAULT_SIGBUS;
 	}
 
-	if (rc == VM_FAULT_NOPAGE) {
-		unsigned long i;
-		pgoff_t pgoff;
-
-		/*
-		 * In the device-dax case the only possibility for a
-		 * VM_FAULT_NOPAGE result is when device-dax capacity is
-		 * mapped. No need to consider the zero page, or racing
-		 * conflicting mappings.
-		 */
-		pgoff = linear_page_index(vmf->vma,
-				ALIGN(vmf->address, fault_size));
-		for (i = 0; i < fault_size / PAGE_SIZE; i++) {
-			struct page *page;
-
-			page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
-			if (page->mapping)
-				continue;
-			page->mapping = filp->f_mapping;
-			page->index = pgoff + i;
-		}
-	}
+	if (rc == VM_FAULT_NOPAGE)
+		dax_set_mapping(vmf, pfn, fault_size);
 	dax_read_unlock(id);
 
 	return rc;