[PATCH] vmalloc_to_page helper

After William did the remap_pfn_range change, a very common pattern became:
	page = page_to_pfn(vmalloc_to_page((void *)pos));
	if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED)) {

the patch below adds a very simple helper, vmalloc_to_pfn() to simplify this
a bit.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/media/video/cpia.c

@@ -3781,7 +3781,7 @@ static int cpia_mmap(struct file *file, struct vm_area_struct *vma)
 
 	pos = (unsigned long)(cam->frame_buf);
 	while (size > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED)) {
 			up(&cam->busy_lock);
 			return -EAGAIN;

drivers/media/video/meye.c

@@ -1188,7 +1188,7 @@ static int meye_mmap(struct file *file, struct vm_area_struct *vma) {
 	pos = (unsigned long)meye.grab_fbuffer;
 
 	while (size > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED)) {
 			up(&meye.lock);
 			return -EAGAIN;

drivers/usb/media/ov511.c

@@ -4756,7 +4756,7 @@ ov51x_v4l1_mmap(struct file *file, struct vm_area_struct *vma)
 
 	pos = (unsigned long)ov->fbuf;
 	while (size > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED)) {
 			up(&ov->lock);
 			return -EAGAIN;

drivers/usb/media/se401.c

@@ -1168,7 +1168,7 @@ static int se401_mmap(struct file *file, struct vm_area_struct *vma)
 	}
 	pos = (unsigned long)se401->fbuf;
 	while (size > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED)) {
 			up(&se401->lock);
 			return -EAGAIN;

drivers/usb/media/sn9c102_core.c

@@ -1555,7 +1555,7 @@ static int sn9c102_mmap(struct file* filp, struct vm_area_struct *vma)
 
 	pos = (unsigned long)cam->frame[i].bufmem;
 	while (size > 0) { /* size is page-aligned */
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE,
 		                     vma->vm_page_prot)) {
 			up(&cam->fileop_sem);

drivers/usb/media/stv680.c

@@ -1277,7 +1277,7 @@ static int stv680_mmap (struct file *file, struct vm_area_struct *vma)
 	}
 	pos = (unsigned long) stv680->fbuf;
 	while (size > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED)) {
 			up (&stv680->lock);
 			return -EAGAIN;

drivers/usb/media/usbvideo.c

@@ -1153,7 +1153,7 @@ static int usbvideo_v4l_mmap(struct file *file, struct vm_area_struct *vma)
 
 	pos = (unsigned long) uvd->fbuf;
 	while (size > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
 			return -EAGAIN;
 

drivers/usb/media/vicam.c

@@ -1045,7 +1045,7 @@ vicam_mmap(struct file *file, struct vm_area_struct *vma)
 
 	pos = (unsigned long)cam->framebuf;
 	while (size > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
 			return -EAGAIN;
 

drivers/usb/media/w9968cf.c

@@ -2904,7 +2904,7 @@ static int w9968cf_mmap(struct file* filp, struct vm_area_struct *vma)
 		return -EINVAL;
 
 	while (vsize > 0) {
-		page = page_to_pfn(vmalloc_to_page((void *)pos));
+		page = vmalloc_to_pfn((void *)pos);
 		if (remap_pfn_range(vma, start, page + vma->vm_pgoff,
 						PAGE_SIZE, vma->vm_page_prot))
 			return -EAGAIN;

include/linux/mm.h

@@ -758,6 +758,7 @@ static inline unsigned long vma_pages(struct vm_area_struct *vma)
 extern struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr);
 
 extern struct page * vmalloc_to_page(void *addr);
+extern unsigned long vmalloc_to_pfn(void *addr);
 extern struct page * follow_page(struct mm_struct *mm, unsigned long address,
 		int write);
 int remap_pfn_range(struct vm_area_struct *, unsigned long,

mm/memory.c

@@ -1805,6 +1805,16 @@ struct page * vmalloc_to_page(void * vmalloc_addr)
 
 EXPORT_SYMBOL(vmalloc_to_page);
 
+/*
+ * Map a vmalloc()-space virtual address to the physical page frame number.
+ */
+unsigned long vmalloc_to_pfn(void * vmalloc_addr)
+{
+	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
+}
+
+EXPORT_SYMBOL(vmalloc_to_pfn);
+
 #if !defined(CONFIG_ARCH_GATE_AREA)
 
 #if defined(AT_SYSINFO_EHDR)

mm/nommu.c

@@ -144,6 +144,12 @@ struct page * vmalloc_to_page(void *addr)
 	return virt_to_page(addr);
 }
 
+unsigned long vmalloc_to_pfn(void *addr)
+{
+	return page_to_pfn(virt_to_page(addr));
+}
+
+
 long vread(char *buf, char *addr, unsigned long count)
 {
 	memcpy(buf, addr, count);