[RFC,3/7] blkdebug: Basic request passthrough

diff --git a/Makefile.objs b/Makefile.objs
index e791dd5..ece02d5 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -14,7 +14,7 @@  block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
 
 block-nested-y += cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o
 block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
-block-nested-y += parallels.o nbd.o
+block-nested-y += parallels.o nbd.o blkdebug.o
 block-nested-$(CONFIG_WIN32) += raw-win32.o
 block-nested-$(CONFIG_POSIX) += raw-posix.o
 block-nested-$(CONFIG_CURL) += curl.o
diff --git a/block/blkdebug.c b/block/blkdebug.c
new file mode 100644
index 0000000..2c7e0dd
--- /dev/null
+++ b/block/blkdebug.c
@@ -0,0 +1,104 @@ 
+/*
+ * Block protocol for I/O error injection
+ *
+ * Copyright (c) 2010 Kevin Wolf <kwolf@redhat.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu-common.h"
+#include "block_int.h"
+#include "module.h"
+
+typedef struct BDRVBlkdebugState {
+    BlockDriverState *hd;
+} BDRVBlkdebugState;
+
+static int blkdebug_open(BlockDriverState *bs, const char *filename, int flags)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+
+    if (strncmp(filename, "blkdebug:", strlen("blkdebug:"))) {
+        return -EINVAL;
+    }
+    filename += strlen("blkdebug:");
+
+    return bdrv_file_open(&s->hd, filename, flags);
+}
+
+static BlockDriverAIOCB *blkdebug_aio_readv(BlockDriverState *bs,
+    int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+    BlockDriverCompletionFunc *cb, void *opaque)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+    BlockDriverAIOCB *acb =
+        bdrv_aio_readv(s->hd, sector_num, qiov, nb_sectors, cb, opaque);
+    return acb;
+}
+
+static BlockDriverAIOCB *blkdebug_aio_writev(BlockDriverState *bs,
+    int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+    BlockDriverCompletionFunc *cb, void *opaque)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+    BlockDriverAIOCB *acb =
+        bdrv_aio_writev(s->hd, sector_num, qiov, nb_sectors, cb, opaque);
+    return acb;
+}
+
+static void blkdebug_close(BlockDriverState *bs)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+    bdrv_delete(s->hd);
+}
+
+static void blkdebug_flush(BlockDriverState *bs)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+    bdrv_flush(s->hd);
+}
+
+static BlockDriverAIOCB *blkdebug_aio_flush(BlockDriverState *bs,
+    BlockDriverCompletionFunc *cb, void *opaque)
+{
+    BDRVBlkdebugState *s = bs->opaque;
+    return bdrv_aio_flush(s->hd, cb, opaque);
+}
+
+static BlockDriver bdrv_blkdebug = {
+    .format_name        = "blkdebug",
+    .protocol_name      = "blkdebug",
+
+    .instance_size      = sizeof(BDRVBlkdebugState),
+
+    .bdrv_open          = blkdebug_open,
+    .bdrv_close         = blkdebug_close,
+    .bdrv_flush         = blkdebug_flush,
+
+    .bdrv_aio_readv     = blkdebug_aio_readv,
+    .bdrv_aio_writev    = blkdebug_aio_writev,
+    .bdrv_aio_flush     = blkdebug_aio_flush,
+};
+
+static void bdrv_blkdebug_init(void)
+{
+    bdrv_register(&bdrv_blkdebug);
+}
+
+block_init(bdrv_blkdebug_init);