Index: linux-2.4.20-8/drivers/block/loop.c
===================================================================
--- linux-2.4.20-8.orig/drivers/block/loop.c	2002-11-29 07:53:12.000000000 +0800
+++ linux-2.4.20-8/drivers/block/loop.c	2004-01-10 00:02:33.000000000 +0800
@@ -843,6 +843,31 @@
 	}
 	return copy_to_user(arg, &info, sizeof(info)) ? -EFAULT : 0;
 }
+static int loop_get_info(struct loop_device *lo, struct loop_info *arg)
+{
+	struct loop_info	info;
+	struct file *file = lo->lo_backing_file;
+
+	if (lo->lo_state != Lo_bound)
+		return -ENXIO;
+	if (!arg)
+		return -EINVAL;
+	memset(&info, 0, sizeof(info));
+	info.lo_number = lo->lo_number;
+	info.lo_device = kdev_t_to_nr(file->f_dentry->d_inode->i_dev);
+	info.lo_inode = file->f_dentry->d_inode->i_ino;
+	info.lo_rdevice = kdev_t_to_nr(lo->lo_device);
+	info.lo_offset = lo->lo_offset;
+	info.lo_flags = lo->lo_flags;
+	strncpy(info.lo_name, lo->lo_name, LO_NAME_SIZE);
+	info.lo_encrypt_type = lo->lo_encrypt_type;
+	if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
+		info.lo_encrypt_key_size = lo->lo_encrypt_key_size;
+		memcpy(info.lo_encrypt_key, lo->lo_encrypt_key,
+		       lo->lo_encrypt_key_size);
+	}
+	return memcpy(arg, &info, sizeof(info)) ? -EFAULT : 0;
+}
 
 static int lo_ioctl(struct inode * inode, struct file * file,
 	unsigned int cmd, unsigned long arg)
@@ -875,6 +900,9 @@
 	case LOOP_GET_STATUS:
 		err = loop_get_status(lo, (struct loop_info *) arg);
 		break;
+	case LOOP_GET_INFO:
+		err = loop_get_info(lo, (struct loop_info *) arg);
+		break;
 	case BLKGETSIZE:
 		if (lo->lo_state != Lo_bound) {
 			err = -ENXIO;
Index: linux-2.4.20-8/include/linux/loop.h
===================================================================
--- linux-2.4.20-8.orig/include/linux/loop.h	2001-09-18 04:16:30.000000000 +0800
+++ linux-2.4.20-8/include/linux/loop.h	2004-01-09 23:50:17.000000000 +0800
@@ -151,5 +151,6 @@
 #define LOOP_CLR_FD	0x4C01
 #define LOOP_SET_STATUS	0x4C02
 #define LOOP_GET_STATUS	0x4C03
+#define LOOP_GET_INFO	0x4C04
 
 #endif