autofs4: don't open-code fd_install()

The only difference between autofs_dev_ioctl_fd_install() and
fd_install() is __set_close_on_exec() done by the latter.  Just
use get_unused_fd_flags(O_CLOEXEC) to allocate the descriptor
and be done with that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/autofs4/dev-ioctl.c

@@ -221,20 +221,6 @@ static int test_by_type(struct path *path, void *p)
 	return ino && ino->sbi->type & *(unsigned *)p;
 }
 
-static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
-{
-	struct files_struct *files = current->files;
-	struct fdtable *fdt;
-
-	spin_lock(&files->file_lock);
-	fdt = files_fdtable(files);
-	BUG_ON(fdt->fd[fd] != NULL);
-	rcu_assign_pointer(fdt->fd[fd], file);
-	__set_close_on_exec(fd, fdt);
-	spin_unlock(&files->file_lock);
-}
-
-
 /*
  * Open a file descriptor on the autofs mount point corresponding
  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
@@ -243,7 +229,7 @@ static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 {
 	int err, fd;
 
-	fd = get_unused_fd();
+	fd = get_unused_fd_flags(O_CLOEXEC);
 	if (likely(fd >= 0)) {
 		struct file *filp;
 		struct path path;
@@ -264,7 +250,7 @@ static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 			goto out;
 		}
 
-		autofs_dev_ioctl_fd_install(fd, filp);
+		fd_install(fd, filp);
 	}
 
 	return fd;