diff --git a/ChangeLog b/ChangeLog
index d7ae963dd..54a51afc0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2010-02-03  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	* util/hostdisk.c (open_device): Don't use partition device when reading
+	before the partition.
+	(grub_util_biosdisk_read): Don't read from partition and before the
+	partition in single operation.
+	(grub_util_biosdisk_write): Don't write to partition and before the
+	partition in single operation.
+
 2010-02-03  Torsten Landschoff   <torsten@debian.org>
 
 	* kern/disk.c (grub_disk_read): Fix offset computation when reading
diff --git a/util/hostdisk.c b/util/hostdisk.c
index a594f75ec..5c56b7579 100644
--- a/util/hostdisk.c
+++ b/util/hostdisk.c
@@ -336,7 +336,8 @@ open_device (const grub_disk_t disk, grub_disk_addr_t sector, int flags)
     char dev[PATH_MAX];
 
     strcpy (dev, map[disk->id].device);
-    if (disk->partition && strncmp (map[disk->id].device, "/dev/", 5) == 0)
+    if (disk->partition && sector >= disk->partition->start
+	&& strncmp (map[disk->id].device, "/dev/", 5) == 0)
       is_partition = linux_find_partition (dev, disk->partition->start);
 
     /* Open the partition.  */
@@ -490,6 +491,23 @@ grub_util_biosdisk_read (grub_disk_t disk, grub_disk_addr_t sector,
 {
   int fd;
 
+  /* Split pre-partition and partition reads.  */
+  if (disk->partition && sector < disk->partition->start
+      && sector + size > disk->partition->start)
+    {
+      grub_err_t err;
+      err = grub_util_biosdisk_read (disk, sector,
+				     disk->partition->start - sector,
+				     buf);
+      if (err)
+	return err;
+
+      return grub_util_biosdisk_read (disk, disk->partition->start,
+				      size - (disk->partition->start - sector),
+				      buf + ((disk->partition->start - sector)
+					     << GRUB_DISK_SECTOR_BITS));
+    }
+
   fd = open_device (disk, sector, O_RDONLY);
   if (fd < 0)
     return grub_errno;
@@ -527,6 +545,23 @@ grub_util_biosdisk_write (grub_disk_t disk, grub_disk_addr_t sector,
 {
   int fd;
 
+  /* Split pre-partition and partition writes.  */
+  if (disk->partition && sector < disk->partition->start
+      && sector + size > disk->partition->start)
+    {
+      grub_err_t err;
+      err = grub_util_biosdisk_write (disk, sector,
+				      disk->partition->start - sector,
+				      buf);
+      if (err)
+	return err;
+
+      return grub_util_biosdisk_write (disk, disk->partition->start,
+				       size - (disk->partition->start - sector),
+				       buf + ((disk->partition->start - sector)
+					      << GRUB_DISK_SECTOR_BITS));
+    }
+
   fd = open_device (disk, sector, O_WRONLY);
   if (fd < 0)
     return grub_errno;