autofs4: Pushdown the bkl from ioctl

Pushdown the bkl to autofs4_root_ioctl.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Autofs <autofs@linux.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>

fs/autofs4/root.c

@@ -18,13 +18,14 @@
 #include <linux/slab.h>
 #include <linux/param.h>
 #include <linux/time.h>
+#include <linux/smp_lock.h>
 #include "autofs_i.h"
 
 static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
 static int autofs4_dir_unlink(struct inode *,struct dentry *);
 static int autofs4_dir_rmdir(struct inode *,struct dentry *);
 static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
-static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
+static long autofs4_root_ioctl(struct file *,unsigned int,unsigned long);
 static int autofs4_dir_open(struct inode *inode, struct file *file);
 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
 static void *autofs4_follow_link(struct dentry *, struct nameidata *);
@@ -38,7 +39,7 @@ const struct file_operations autofs4_root_operations = {
 	.read		= generic_read_dir,
 	.readdir	= dcache_readdir,
 	.llseek		= dcache_dir_lseek,
-	.ioctl		= autofs4_root_ioctl,
+	.unlocked_ioctl	= autofs4_root_ioctl,
 };
 
 const struct file_operations autofs4_dir_operations = {
@@ -902,8 +903,8 @@ int is_autofs4_dentry(struct dentry *dentry)
  * ioctl()'s on the root directory is the chief method for the daemon to
  * generate kernel reactions
  */
-static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
-			     unsigned int cmd, unsigned long arg)
+static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
+				       unsigned int cmd, unsigned long arg)
 {
 	struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 	void __user *p = (void __user *)arg;
@@ -947,3 +948,16 @@ static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 		return -ENOSYS;
 	}
 }
+
+static long autofs4_root_ioctl(struct file *filp,
+			       unsigned int cmd, unsigned long arg)
+{
+	long ret;
+	struct inode *inode = filp->f_dentry->d_inode;
+
+	lock_kernel();
+	ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
+	unlock_kernel();
+
+	return ret;
+}