diff --git a/block.c b/block.c
index 1e49bc0..6fdabff 100644
--- a/block.c
+++ b/block.c
@@ -43,6 +43,7 @@
 
 #define SECTOR_BITS 9
 #define SECTOR_SIZE (1 << SECTOR_BITS)
+#define SECTORS_PER_DIRTY_CHUNK 8
 
 static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
@@ -641,6 +642,18 @@
     return drv->bdrv_read(bs, sector_num, buf, nb_sectors);
 }
 
+static void set_dirty_bitmap(BlockDriverState *bs, int64_t sector_num,
+			     int nb_sectors, int dirty)
+{
+    int64_t start, end;
+    start = sector_num / SECTORS_PER_DIRTY_CHUNK;
+    end = (sector_num + nb_sectors) / SECTORS_PER_DIRTY_CHUNK;
+    
+    for(; start <= end; start++) {
+        bs->dirty_bitmap[start] = dirty;
+    }
+}
+
 /* Return < 0 if error. Important errors are:
   -EIO         generic I/O error (may happen for all errors)
   -ENOMEDIUM   No media inserted.
@@ -657,7 +670,11 @@
         return -EACCES;
     if (bdrv_check_request(bs, sector_num, nb_sectors))
         return -EIO;
-
+    
+    if(bs->dirty_tracking) {
+        set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
+    }
+    
     return drv->bdrv_write(bs, sector_num, buf, nb_sectors);
 }
 
@@ -1203,6 +1220,11 @@
         return -ENOTSUP;
     if (bdrv_check_request(bs, sector_num, nb_sectors))
         return -EIO;
+    
+    if(bs->dirty_tracking) {
+        set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
+    }
+    
     return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);
 }
 
@@ -1400,6 +1422,10 @@
     if (bdrv_check_request(bs, sector_num, nb_sectors))
         return NULL;
 
+    if(bs->dirty_tracking) {
+        set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
+    }
+    
     ret = drv->bdrv_aio_writev(bs, sector_num, qiov, nb_sectors,
                                cb, opaque);
 
@@ -1930,7 +1956,57 @@
     return NULL;
 }
 
+
+
 void *qemu_blockalign(BlockDriverState *bs, size_t size)
 {
     return qemu_memalign((bs && bs->buffer_alignment) ? bs->buffer_alignment : 512, size);
 }
+
+void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable)
+{
+    int64_t bitmap_size;
+    if(enable) {
+        if(bs->dirty_tracking == 0) {
+            int64_t i;
+            uint8_t test;
+            bitmap_size = (bdrv_getlength(bs) >> SECTOR_BITS);
+            bitmap_size /= SECTORS_PER_DIRTY_CHUNK;
+            bitmap_size++;
+	    
+            bs->dirty_bitmap = qemu_mallocz(bitmap_size);
+	    
+            bs->dirty_tracking = enable;
+            for(i = 0; i < bitmap_size; i++) test = bs->dirty_bitmap[i]; 
+	}
+    } else {
+        if(bs->dirty_tracking != 0) {
+            qemu_free(bs->dirty_bitmap);
+            bs->dirty_tracking = enable;
+	}
+    }
+}
+
+int bdrv_get_dirty(BlockDriverState *bs, int64_t sector)
+{
+    int64_t chunk = sector / (int64_t)SECTORS_PER_DIRTY_CHUNK;
+    
+    if(bs->dirty_bitmap != NULL && 
+       (sector << SECTOR_BITS) <= bdrv_getlength(bs)) {
+        return bs->dirty_bitmap[chunk];
+    } else {
+        return 0;
+    }
+}
+
+void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, 
+		      int nr_sectors)
+{
+    set_dirty_bitmap(bs, cur_sector, nr_sectors, 0);
+}
+
+int bdrv_get_sectors_per_chunk(void)
+{
+    /* size must be 2^x */
+    return SECTORS_PER_DIRTY_CHUNK;
+}