mm: inline vm_insert_pfn_prot() into caller

vm_insert_pfn_prot() is only called from vmf_insert_pfn_prot(), so inline
it and convert some of the errnos into vm_fault codes earlier.

Link: http://lkml.kernel.org/r/20180828145728.11873-9-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

@@ -1572,36 +1572,6 @@ out:
 	return retval;
 }
 
-static int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
-			unsigned long pfn, pgprot_t pgprot)
-{
-	int ret;
-	/*
-	 * Technically, architectures with pte_special can avoid all these
-	 * restrictions (same for remap_pfn_range).  However we would like
-	 * consistency in testing and feature parity among all, so we should
-	 * try to keep these invariants in place for everybody.
-	 */
-	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
-	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
-						(VM_PFNMAP|VM_MIXEDMAP));
-	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
-	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
-
-	if (addr < vma->vm_start || addr >= vma->vm_end)
-		return -EFAULT;
-
-	if (!pfn_modify_allowed(pfn, pgprot))
-		return -EACCES;
-
-	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
-
-	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
-			false);
-
-	return ret;
-}
-
 /**
  * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
  * @vma: user vma to map to
@@ -1623,7 +1593,30 @@ static int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn, pgprot_t pgprot)
 {
-	int err = vm_insert_pfn_prot(vma, addr, pfn, pgprot);
+	int err;
+
+	/*
+	 * Technically, architectures with pte_special can avoid all these
+	 * restrictions (same for remap_pfn_range).  However we would like
+	 * consistency in testing and feature parity among all, so we should
+	 * try to keep these invariants in place for everybody.
+	 */
+	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
+	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
+						(VM_PFNMAP|VM_MIXEDMAP));
+	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
+	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
+
+	if (addr < vma->vm_start || addr >= vma->vm_end)
+		return VM_FAULT_SIGBUS;
+
+	if (!pfn_modify_allowed(pfn, pgprot))
+		return VM_FAULT_SIGBUS;
+
+	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,
+			false);
 
 	if (err == -ENOMEM)
 		return VM_FAULT_OOM;