wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 68f0314..44a74cf 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -215,9 +215,9 @@
 		newattrs.ia_uid = uid;
 		newattrs.ia_gid = gid;
 		newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
-		mutex_lock(&d_inode(dentry)->i_mutex);
+		inode_lock(d_inode(dentry));
 		notify_change(dentry, &newattrs, NULL);
-		mutex_unlock(&d_inode(dentry)->i_mutex);
+		inode_unlock(d_inode(dentry));
 
 		/* mark as kernel-created inode */
 		d_inode(dentry)->i_private = &thread;
@@ -244,7 +244,7 @@
 		err = -ENOENT;
 	}
 	dput(dentry);
-	mutex_unlock(&d_inode(parent.dentry)->i_mutex);
+	inode_unlock(d_inode(parent.dentry));
 	path_put(&parent);
 	return err;
 }
@@ -321,9 +321,9 @@
 			newattrs.ia_mode = stat.mode & ~0777;
 			newattrs.ia_valid =
 				ATTR_UID|ATTR_GID|ATTR_MODE;
-			mutex_lock(&d_inode(dentry)->i_mutex);
+			inode_lock(d_inode(dentry));
 			notify_change(dentry, &newattrs, NULL);
-			mutex_unlock(&d_inode(dentry)->i_mutex);
+			inode_unlock(d_inode(dentry));
 			err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
 			if (!err || err == -ENOENT)
 				deleted = 1;
@@ -332,7 +332,7 @@
 		err = -ENOENT;
 	}
 	dput(dentry);
-	mutex_unlock(&d_inode(parent.dentry)->i_mutex);
+	inode_unlock(d_inode(parent.dentry));
 
 	path_put(&parent);
 	if (deleted && strchr(nodename, '/'))