ext4: rename EXT4_IOC_GOINGDOWN to EXT4_IOC_SHUTDOWN

It's very likely the file system independent ioctl name will be
FS_IOC_SHUTDOWN, so let's use the same name for the ext4 ioctl name.
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -679,7 +679,7 @@ struct fsxattr {
 #define EXT4_IOC_FSGETXATTR		FS_IOC_FSGETXATTR
 #define EXT4_IOC_FSSETXATTR		FS_IOC_FSSETXATTR
 
-#define EXT4_IOC_GOINGDOWN _IOR ('X', 125, __u32)
+#define EXT4_IOC_SHUTDOWN _IOR ('X', 125, __u32)
 
 /*
  * Flags for going down operation

fs/ext4/ioctl.c

@@ -443,7 +443,7 @@ static inline unsigned long ext4_xflags_to_iflags(__u32 xflags)
 	return iflags;
 }
 
-int ext4_goingdown(struct super_block *sb, unsigned long arg)
+int ext4_shutdown(struct super_block *sb, unsigned long arg)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	__u32 flags;
@@ -940,8 +940,8 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 
 		return 0;
 	}
-	case EXT4_IOC_GOINGDOWN:
-		return ext4_goingdown(sb, arg);
+	case EXT4_IOC_SHUTDOWN:
+		return ext4_shutdown(sb, arg);
 	default:
 		return -ENOTTY;
 	}
@@ -1008,7 +1008,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case EXT4_IOC_SET_ENCRYPTION_POLICY:
 	case EXT4_IOC_GET_ENCRYPTION_PWSALT:
 	case EXT4_IOC_GET_ENCRYPTION_POLICY:
-	case EXT4_IOC_GOINGDOWN:
+	case EXT4_IOC_SHUTDOWN:
 		break;
 	default:
 		return -ENOIOCTLCMD;