Very small patch to 0.99pl12

I hate to put out patches this soon after a release, but there is one
potentially major problem in pl12 which is very simple to fix..  I'm
including patches: both in plain ascii and as a uuencoded gzip file
(it's the same patch - the uuencoded one is in case there is any
newsserver that messes up whitespace).

The main patch is just the change from __get_free_page(GFP_BUFFER) into
get_free_page(GFP_KERNEL), and the two minor patches just add checks
that actually enforce the read-only nature of current file mmap'ings so
that any program that tries to do a write mapping at least will be told
that it won't work.

I'd suggest anybody compiling pl12 should add at least the file_table.c
patch: thanks to Alexandre Julliard for noticing this one.

            Linus

fs/file_table.c

@@ -45,7 +45,7 @@ void grow_files(void)
 	struct file * file;
 	int i;
 
-	file = (struct file*) __get_free_page(GFP_BUFFER);
+	file = (struct file *) get_free_page(GFP_KERNEL);
 
 	if (!file)
 		return;

fs/nfs/mmap.c

@@ -50,6 +50,8 @@ int nfs_mmap(struct inode * inode, struct file * file,
 {
 	struct vm_area_struct * mpnt;
 
+	if (prot & PAGE_RW)	/* only PAGE_COW or read-only supported now */
+		return -EINVAL;
 	if (off & (inode->i_sb->s_blocksize - 1))
 		return -EINVAL;
 	if (len > high_memory || off > high_memory - len) /* avoid overflow */

mm/mmap.c

@@ -197,6 +197,8 @@ int generic_mmap(struct inode * inode, struct file * file,
 	extern struct vm_operations_struct file_mmap;
 	struct buffer_head * bh;
 
+	if (prot & PAGE_RW)	/* only PAGE_COW or read-only supported right now */
+		return -EINVAL;
 	if (off & (inode->i_sb->s_blocksize - 1))
 		return -EINVAL;
 	if (len > high_memory || off > high_memory - len) /* avoid overflow */