mm: convert insert_pfn() to vm_fault_t

All callers convert its errno into a vm_fault_t, so convert it to return a
vm_fault_t directly.

Link: http://lkml.kernel.org/r/20180828145728.11873-11-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -1520,19 +1520,16 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(vm_insert_page);
 
-static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 			pfn_t pfn, pgprot_t prot, bool mkwrite)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	int retval;
 	pte_t *pte, entry;
 	spinlock_t *ptl;
 
-	retval = -ENOMEM;
 	pte = get_locked_pte(mm, addr, &ptl);
 	if (!pte)
-		goto out;
-	retval = -EBUSY;
+		return VM_FAULT_OOM;
 	if (!pte_none(*pte)) {
 		if (mkwrite) {
 			/*
@@ -1565,11 +1562,9 @@ out_mkwrite:
 	set_pte_at(mm, addr, pte, entry);
 	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
 
-	retval = 0;
 out_unlock:
 	pte_unmap_unlock(pte, ptl);
-out:
-	return retval;
+	return VM_FAULT_NOPAGE;
 }
 
 /**
@@ -1593,8 +1588,6 @@ out:
 vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn, pgprot_t pgprot)
 {
-	int err;
-
 	/*
 	 * Technically, architectures with pte_special can avoid all these
 	 * restrictions (same for remap_pfn_range).  However we would like
@@ -1615,15 +1608,8 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 
 	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
 
-	err = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
+	return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
 			false);
-
-	if (err == -ENOMEM)
-		return VM_FAULT_OOM;
-	if (err < 0 && err != -EBUSY)
-		return VM_FAULT_SIGBUS;
-
-	return VM_FAULT_NOPAGE;
 }
 EXPORT_SYMBOL(vmf_insert_pfn_prot);
 
@@ -1703,7 +1689,7 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
 		page = pfn_to_page(pfn_t_to_pfn(pfn));
 		err = insert_page(vma, addr, page, pgprot);
 	} else {
-		err = insert_pfn(vma, addr, pfn, pgprot, mkwrite);
+		return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
 	}
 
 	if (err == -ENOMEM)