mm: use is_cow_mapping() across tree where proper

After is_cow_mapping() is exported in mm.h, replace some manual checks
elsewhere throughout the tree but start to use the new helper.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Cc: VMware Graphics <[email protected]>
Cc: Roland Scheidegger <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: David Gibson <[email protected]>
Cc: Gal Pressman <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Kirill Shutemov <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Wei Zhang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: xzpeter

drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c

@@ -500,8 +500,6 @@ vm_fault_t vmw_bo_vm_huge_fault(struct vm_fault *vmf,
 	vm_fault_t ret;
 	pgoff_t fault_page_size;
 	bool write = vmf->flags & FAULT_FLAG_WRITE;
-	bool is_cow_mapping =
-		(vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 
 	switch (pe_size) {
 	case PE_SIZE_PMD:
@@ -518,7 +516,7 @@ vm_fault_t vmw_bo_vm_huge_fault(struct vm_fault *vmf,
 	}
 
 	/* Always do write dirty-tracking and COW on PTE level. */
-	if (write && (READ_ONCE(vbo->dirty) || is_cow_mapping))
+	if (write && (READ_ONCE(vbo->dirty) || is_cow_mapping(vma->vm_flags)))
 		return VM_FAULT_FALLBACK;
 
 	ret = ttm_bo_vm_reserve(bo, vmf);

drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c

@@ -49,7 +49,7 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
 	vma->vm_ops = &vmw_vm_ops;
 
 	/* Use VM_PFNMAP rather than VM_MIXEDMAP if not a COW mapping */
-	if ((vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) != VM_MAYWRITE)
+	if (!is_cow_mapping(vma->vm_flags))
 		vma->vm_flags = (vma->vm_flags & ~VM_MIXEDMAP) | VM_PFNMAP;
 
 	return 0;

fs/proc/task_mmu.c

@@ -1036,8 +1036,6 @@ struct clear_refs_private {
 
 #ifdef CONFIG_MEM_SOFT_DIRTY
 
-#define is_cow_mapping(flags) (((flags) & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE)
-
 static inline bool pte_is_pinned(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
 {
 	struct page *page;

mm/hugetlb.c

@@ -3734,15 +3734,13 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 	pte_t *src_pte, *dst_pte, entry, dst_entry;
 	struct page *ptepage;
 	unsigned long addr;
-	int cow;
+	bool cow = is_cow_mapping(vma->vm_flags);
 	struct hstate *h = hstate_vma(vma);
 	unsigned long sz = huge_page_size(h);
 	struct address_space *mapping = vma->vm_file->f_mapping;
 	struct mmu_notifier_range range;
 	int ret = 0;
 
-	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
-
 	if (cow) {
 		mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, src,
 					vma->vm_start,