proc_map_files_readdir(): don't bother with grabbing files

all we need is their ->f_mode, so just collect _that_
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/proc/base.c

@@ -1805,7 +1805,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path)
 }
 
 struct map_files_info {
-	struct file	*file;
+	fmode_t		mode;
 	unsigned long	len;
 	unsigned char	name[4*sizeof(long)+2]; /* max: %lx-%lx\0 */
 };
@@ -1814,13 +1814,10 @@ static struct dentry *
 proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
 			   struct task_struct *task, const void *ptr)
 {
-	const struct file *file = ptr;
+	fmode_t mode = (fmode_t)(unsigned long)ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
-	if (!file)
-		return ERR_PTR(-ENOENT);
-
 	inode = proc_pid_make_inode(dir->i_sb, task);
 	if (!inode)
 		return ERR_PTR(-ENOENT);
@@ -1832,9 +1829,9 @@ proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
 	inode->i_size = 64;
 	inode->i_mode = S_IFLNK;
 
-	if (file->f_mode & FMODE_READ)
+	if (mode & FMODE_READ)
 		inode->i_mode |= S_IRUSR;
-	if (file->f_mode & FMODE_WRITE)
+	if (mode & FMODE_WRITE)
 		inode->i_mode |= S_IWUSR;
 
 	d_set_d_op(dentry, &tid_map_files_dentry_operations);
@@ -1878,7 +1875,8 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 	if (!vma)
 		goto out_no_vma;
 
-	result = proc_map_files_instantiate(dir, dentry, task, vma->vm_file);
+	result = proc_map_files_instantiate(dir, dentry, task,
+			(void *)(unsigned long)vma->vm_file->f_mode);
 
 out_no_vma:
 	up_read(&mm->mmap_sem);
@@ -1979,7 +1977,7 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 				if (++pos <= filp->f_pos)
 					continue;
 
-				info.file = get_file(vma->vm_file);
+				info.mode = vma->vm_file->f_mode;
 				info.len = snprintf(info.name,
 						sizeof(info.name), "%lx-%lx",
 						vma->vm_start, vma->vm_end);
@@ -1994,19 +1992,11 @@ proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
 			ret = proc_fill_cache(filp, dirent, filldir,
 					      p->name, p->len,
 					      proc_map_files_instantiate,
-					      task, p->file);
+					      task,
+					      (void *)(unsigned long)p->mode);
 			if (ret)
 				break;
 			filp->f_pos++;
-			fput(p->file);
-		}
-		for (; i < nr_files; i++) {
-			/*
-			 * In case of error don't forget
-			 * to put rest of file refs.
-			 */
-			p = flex_array_get(fa, i);
-			fput(p->file);
 		}
 		if (fa)
 			flex_array_free(fa);