get_unmapped_area handles MAP_FIXED in generic code

generic arch_get_unmapped_area() now handles MAP_FIXED.  Now that all
implementations have been fixed, change the toplevel get_unmapped_area() to
call into arch or drivers for the MAP_FIXED case.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: William Irwin <bill.irwin@oracle.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mmap.c

@@ -1200,6 +1200,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
+	if (flags & MAP_FIXED)
+		return addr;
+
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
@@ -1273,6 +1276,9 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
+	if (flags & MAP_FIXED)
+		return addr;
+
 	/* requesting a specific address */
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
@@ -1361,9 +1367,8 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 		unsigned long pgoff, unsigned long flags)
 {
 	unsigned long ret;
-
-	if (!(flags & MAP_FIXED)) {
-		unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
+	unsigned long (*get_area)(struct file *, unsigned long,
+				  unsigned long, unsigned long, unsigned long);
 
 	get_area = current->mm->get_unmapped_area;
 	if (file && file->f_op && file->f_op->get_unmapped_area)
@@ -1371,12 +1376,12 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 	addr = get_area(file, addr, len, pgoff, flags);
 	if (IS_ERR_VALUE(addr))
 		return addr;
-	}
 
 	if (addr > TASK_SIZE - len)
 		return -ENOMEM;
 	if (addr & ~PAGE_MASK)
 		return -EINVAL;
+
 	if (file && is_file_hugepages(file))  {
 		/*
 		 * Check if the given range is hugepage aligned, and