diff -urN linux-2.4.10/drivers/block/loop.c linux-2.4.10-iv/drivers/block/loop.c
--- linux-2.4.10/drivers/block/loop.c	Mon Sep 17 22:16:30 2001
+++ linux-2.4.10-iv/drivers/block/loop.c	Sat Sep 29 10:50:18 2001
@@ -36,6 +36,9 @@
  * Al Viro too.
  * Jens Axboe <axboe@suse.de>, Nov 2000
  *
+ * Fixed and made IV calculation customizable by lo_iv_mode
+ * Herbert Valerio Riedel <hvr@gnu.org>, Apr 2001
+ *
  * Still To Fix:
  * - Advisory locking is ignored here. 
  * - Should use an own CAP_* category instead of CAP_SYS_ADMIN 
@@ -168,6 +171,43 @@
 					lo->lo_device);
 }
 
+static inline int loop_get_bs(struct loop_device *lo)
+{
+	int bs = 0;
+
+	if (blksize_size[MAJOR(lo->lo_device)])
+		bs = blksize_size[MAJOR(lo->lo_device)][MINOR(lo->lo_device)];
+	if (!bs)
+		bs = BLOCK_SIZE;	
+
+	return bs;
+}
+
+static inline unsigned long loop_get_iv(struct loop_device *lo,
+					unsigned long sector)
+{
+	unsigned long offset, IV;
+	int bs;
+
+	switch (lo->lo_iv_mode) {
+		case LO_IV_MODE_SECTOR:
+			IV = sector + (lo->lo_offset >> LO_IV_SECTOR_BITS);
+			break;
+
+		default:
+			printk (KERN_WARNING "loop: unexpected lo_iv_mode\n");
+		case LO_IV_MODE_DEFAULT:
+			bs = loop_get_bs(lo);
+			IV = sector / (bs >> 9) + lo->lo_offset / bs;
+			offset = ((sector % (bs >> 9)) << 9) + lo->lo_offset % bs;
+			if (offset >= bs)
+				IV++;
+			break;
+	}
+
+	return IV;
+}
+
 static int lo_send(struct loop_device *lo, struct buffer_head *bh, int bsize,
 		   loff_t pos)
 {
@@ -185,7 +225,8 @@
 	len = bh->b_size;
 	data = bh->b_data;
 	while (len > 0) {
-		int IV = index * (PAGE_CACHE_SIZE/bsize) + offset/bsize;
+		unsigned long IV = loop_get_iv(lo, (pos - lo->lo_offset) >> LO_IV_SECTOR_BITS);
+
 		size = PAGE_CACHE_SIZE - offset;
 		if (size > len)
 			size = len;
@@ -236,7 +277,10 @@
 	unsigned long count = desc->count;
 	struct lo_read_data *p = (struct lo_read_data*)desc->buf;
 	struct loop_device *lo = p->lo;
-	int IV = page->index * (PAGE_CACHE_SIZE/p->bsize) + offset/p->bsize;
+	unsigned long IV = loop_get_iv(lo,
+		((page->index <<  (PAGE_CACHE_SHIFT - LO_IV_SECTOR_BITS))
+		+ (offset >> LO_IV_SECTOR_BITS)
+		- (lo->lo_offset >> LO_IV_SECTOR_BITS)));
 
 	if (size > count)
 		size = count;
@@ -276,32 +320,6 @@
 	return desc.error;
 }
 
-static inline int loop_get_bs(struct loop_device *lo)
-{
-	int bs = 0;
-
-	if (blksize_size[MAJOR(lo->lo_device)])
-		bs = blksize_size[MAJOR(lo->lo_device)][MINOR(lo->lo_device)];
-	if (!bs)
-		bs = BLOCK_SIZE;	
-
-	return bs;
-}
-
-static inline unsigned long loop_get_iv(struct loop_device *lo,
-					unsigned long sector)
-{
-	int bs = loop_get_bs(lo);
-	unsigned long offset, IV;
-
-	IV = sector / (bs >> 9) + lo->lo_offset / bs;
-	offset = ((sector % (bs >> 9)) << 9) + lo->lo_offset % bs;
-	if (offset >= bs)
-		IV++;
-
-	return IV;
-}
-
 static int do_bh_filebacked(struct loop_device *lo, struct buffer_head *bh, int rw)
 {
 	loff_t pos;
@@ -663,6 +681,7 @@
 	lo->lo_backing_file = file;
 	lo->transfer = NULL;
 	lo->ioctl = NULL;
+	lo->lo_iv_mode = LO_IV_MODE_DEFAULT;
 	figure_loop_size(lo);
 	lo->old_gfp_mask = inode->i_mapping->gfp_mask;
 	inode->i_mapping->gfp_mask = GFP_NOIO;
@@ -672,7 +691,7 @@
 		bs = blksize_size[MAJOR(lo_device)][MINOR(lo_device)];
 	if (!bs)
 		bs = BLOCK_SIZE;
-
+	  
 	set_blocksize(dev, bs);
 
 	lo->lo_bh = lo->lo_bhtail = NULL;
diff -urN linux-2.4.10/include/linux/loop.h linux-2.4.10-iv/include/linux/loop.h
--- linux-2.4.10/include/linux/loop.h	Mon Sep 17 22:16:30 2001
+++ linux-2.4.10-iv/include/linux/loop.h	Sat Sep 29 10:50:18 2001
@@ -24,6 +24,13 @@
 	Lo_rundown,
 };
 
+/* IV calculation related constants */
+#define LO_IV_MODE_DEFAULT 0 /* old logical block size based mode */
+#define LO_IV_MODE_SECTOR  1 /* calculate IV based on relative 
+				512 byte sectors */
+#define LO_IV_SECTOR_BITS 9
+#define LO_IV_SECTOR_SIZE (1 << LO_IV_SECTOR_BITS)
+
 struct loop_device {
 	int		lo_number;
 	int		lo_refcnt;
@@ -56,6 +63,8 @@
 	struct semaphore	lo_ctl_mutex;
 	struct semaphore	lo_bh_mutex;
 	atomic_t		lo_pending;
+
+	int			lo_iv_mode;
 };
 
 typedef	int (* transfer_proc_t)(struct loop_device *, int cmd,
@@ -122,6 +131,7 @@
 #define LO_CRYPT_IDEA     6
 #define LO_CRYPT_DUMMY    9
 #define LO_CRYPT_SKIPJACK 10
+#define LO_CRYPT_CRYPTOAPI 18  /* international crypto patch */
 #define MAX_LO_CRYPT	20
 
 #ifdef __KERNEL__