split mmap

This is a straightforward split of do_mmap_pgoff() into two functions:

 - do_mmap_pgoff() checks the parameters, and calculates the vma
   flags.  Then it calls

 - mmap_region(), which does the actual mapping
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -1071,6 +1071,10 @@ extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned lo
 extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,
 	unsigned long flag, unsigned long pgoff);
+extern unsigned long mmap_region(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long flags,
+	unsigned int vm_flags, unsigned long pgoff,
+	int accountable);
 
 static inline unsigned long do_mmap(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,

mm/mmap.c

@@ -894,14 +894,11 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 			unsigned long flags, unsigned long pgoff)
 {
 	struct mm_struct * mm = current->mm;
-	struct vm_area_struct * vma, * prev;
 	struct inode *inode;
 	unsigned int vm_flags;
-	int correct_wcount = 0;
 	int error;
-	struct rb_node ** rb_link, * rb_parent;
 	int accountable = 1;
-	unsigned long charged = 0, reqprot = prot;
+	unsigned long reqprot = prot;
 
 	/*
 	 * Does the application expect PROT_READ to imply PROT_EXEC?
@@ -1027,6 +1024,24 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 	if (error)
 		return error;
 
+	return mmap_region(file, addr, len, flags, vm_flags, pgoff,
+			   accountable);
+}
+EXPORT_SYMBOL(do_mmap_pgoff);
+
+unsigned long mmap_region(struct file *file, unsigned long addr,
+			  unsigned long len, unsigned long flags,
+			  unsigned int vm_flags, unsigned long pgoff,
+			  int accountable)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma, *prev;
+	int correct_wcount = 0;
+	int error;
+	struct rb_node **rb_link, *rb_parent;
+	unsigned long charged = 0;
+	struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
+
 	/* Clear old maps */
 	error = -ENOMEM;
 munmap_back:
@@ -1175,8 +1190,6 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 	return error;
 }
 
-EXPORT_SYMBOL(do_mmap_pgoff);
-
 /* Get an address range which is currently unmapped.
  * For shmat() with addr=0.
  *