Fix block migration when the device size is not a multiple of 1 MB

b02bea3a

 added a check on the return
value of bdrv_write and aborts migration when it fails. However, if the
size of the block device to migrate is not a multiple of BLOCK_SIZE
(currently 1 MB), the last bdrv_write will fail with -EIO.

Fixed by calling bdrv_write with the correct size of the last block.
Signed-off-by: Pierre Riteau <Pierre.Riteau@irisa.fr>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block-migration.c

@@ -638,8 +638,10 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
     int len, flags;
     char device_name[256];
     int64_t addr;
-    BlockDriverState *bs;
+    BlockDriverState *bs, *bs_prev = NULL;
     uint8_t *buf;
+    int64_t total_sectors = 0;
+    int nr_sectors;
 
     do {
         addr = qemu_get_be64(f);
@@ -661,10 +663,26 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
                 return -EINVAL;
             }
 
+            if (bs != bs_prev) {
+                bs_prev = bs;
+                total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+                if (total_sectors <= 0) {
+                    error_report("Error getting length of block device %s\n",
+                                 device_name);
+                    return -EINVAL;
+                }
+            }
+
+            if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
+                nr_sectors = total_sectors - addr;
+            } else {
+                nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
+            }
+
             buf = qemu_malloc(BLOCK_SIZE);
 
             qemu_get_buffer(f, buf, BLOCK_SIZE);
-            ret = bdrv_write(bs, addr, buf, BDRV_SECTORS_PER_DIRTY_CHUNK);
+            ret = bdrv_write(bs, addr, buf, nr_sectors);
 
             qemu_free(buf);
             if (ret < 0) {