From dade09da11e6d7da9c674d376b49eca96c8c115c Mon Sep 17 00:00:00 2001
From: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Date: Tue, 6 Sep 2011 01:10:36 +0800
Subject: [PATCH] still can not re-boot

---
 block/add-cow.c | 37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/block/add-cow.c b/block/add-cow.c
index a2d3546e4b..9daf626444 100644
--- a/block/add-cow.c
+++ b/block/add-cow.c
@@ -125,7 +125,7 @@ static int add_cow_is_allocated(BlockDriverState *bs, int64_t sector_num,
 
     changed = is_bit_set(bs, sector_num);
     if (changed < 0) {
-        return 0; 
+        return 0;
     }
 
     for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {
@@ -197,7 +197,7 @@ static int add_cow_create(const char *filename, QEMUOptionParameter *options)
                 sizeof(add_cow_header.backing_file), backing_filename);
     pstrcpy(add_cow_header.image_file, sizeof(add_cow_header.image_file),
                 image_filename);
-    
+
     add_cow_header.sectorsize = cpu_to_be32(512);
     add_cow_header.size = cpu_to_be64(image_sectors * 512);
 
@@ -207,6 +207,11 @@ static int add_cow_create(const char *filename, QEMUOptionParameter *options)
     }
     bdrv_close(bs);
 
+    ret = bdrv_create_file(image_filename, NULL);
+    if (ret < 0) {
+        return ret;
+    }
+
     BlockDriver* drv = bdrv_find_format("add-cow");
     assert(drv != NULL);
     ret = bdrv_open(bs, filename, BDRV_O_RDWR | BDRV_O_NO_FLUSH, drv);
@@ -265,7 +270,6 @@ static int add_cow_aio_read_cb(void *opaque)
     BDRVAddCowState *s = bs->opaque;
     int ret;
     int n;
- redo:
     acb->nb_sectors -= acb->n;
     acb->sector_num += acb->n;
     acb->buf += acb->n * 512;
@@ -282,12 +286,14 @@ static int add_cow_aio_read_cb(void *opaque)
         qemu_co_mutex_unlock(&s->lock);
         ret = bdrv_co_readv(bs->cow_hd, acb->sector_num,
                             n, &acb->hd_qiov);
-        acb->n = n;
         qemu_co_mutex_lock(&s->lock);
         if (ret < 0) {
             return -EIO;
         }
+        acb->n = n;
+        return 1;
     } else {
+        acb->n = n;
         if (bs->backing_hd) {
             acb->hd_iov.iov_base = (void *)acb->buf;
             acb->hd_iov.iov_len = n * 512;
@@ -299,13 +305,13 @@ static int add_cow_aio_read_cb(void *opaque)
             if (ret < 0) {
                 return -EIO;
             }
+            return 1;
         } else {
             memset(acb->buf, 0, 512 * n);
-            acb->n = n;
-            goto redo;
+            return 1;
         }
         acb->n = n;
-    }   
+    }
 
     return 1;
 }
@@ -349,7 +355,7 @@ static int add_cow_co_readv(BlockDriverState *bs, int64_t sector_num,
     BDRVAddCowState *s = bs->opaque;
     AddCowAIOCB *acb;
     int ret;
-  
+
     acb = add_cow_aio_setup(bs, sector_num, qiov, nb_sectors, 0);
     qemu_co_mutex_lock(&s->lock);
     do {
@@ -422,6 +428,17 @@ static QEMUOptionParameter add_cow_create_options[] = {
     { NULL }
 };
 
+static int add_cow_flush(BlockDriverState *bs)
+{
+    return bdrv_flush(bs->file);
+}
+
+static BlockDriverAIOCB *add_cow_aio_flush(BlockDriverState *bs,
+        BlockDriverCompletionFunc *cb, void *opaque)
+{
+    return bdrv_aio_flush(bs->file, cb, opaque);
+}
+
 static BlockDriver bdrv_add_cow = {
     .format_name        = "add-cow",
     .instance_size      = sizeof(BDRVAddCowState),
@@ -435,7 +452,9 @@ static BlockDriver bdrv_add_cow = {
     .bdrv_co_writev     = add_cow_co_writev,
     .bdrv_truncate      = bdrv_add_cow_truncate,
 
-    .create_options = add_cow_create_options,
+    .create_options     = add_cow_create_options,
+    .bdrv_flush         = add_cow_flush,
+    .bdrv_aio_flush     = add_cow_aio_flush,
 };
 
 static void bdrv_add_cow_init(void)
-- 
2.11.4.GIT