blktap2: a completely rewritten blktap implementation

Benefits to blktap2 over the old version of blktap:

* Isolation from xenstore - Blktap devices are now created directly on
   the linux dom0 command line, rather than being spawned in response
   to XenStore events.  This is handy for debugging, makes blktap
   generally easier to work with, and is a step toward a generic
   user-level block device implementation that is not Xen-specific.

* Improved tapdisk infrastructure: simpler request forwarding, new
   request scheduler, request merging, more efficient use of AIO.

* Improved tapdisk error handling and memory management.  No
   allocations on the block data path, IO retry logic to protect
   guests
   transient block device failures.  This has been tested and is known
   to work on weird environments such as NFS soft mounts.

* Pause and snapshot of live virtual disks (see xmsnap script).

* VHD support.  The VHD code in this release has been rigorously
   tested, and represents a very mature implementation of the VHD
   image
   format.

* No more duplication of mechanism with blkback.  The blktap kernel
   module has changed dramatically from the original blktap.  Blkback
   is now always used to talk to Xen guests, blktap just presents a
   Linux gendisk that blkback can export.  This is done while
   preserving the zero-copy data path from domU to physical device.

These patches deprecate the old blktap code, which can hopefully be
removed from the tree completely at some point in the future.

Signed-off-by: Jake Wires <jake.wires@citrix.com>
Signed-off-by: Dutch Meyer <dmeyer@cs.ubc.ca>

11 files changed, 1285 insertions, 0 deletions

diff --git a/tools/blktap2/include/Makefile b/tools/blktap2/include/Makefile
new file mode 100644
index 0000000000..7267eac53a
--- /dev/null
+++ b/tools/blktap2/include/Makefile
@@ -0,0 +1,14 @@
+XEN_ROOT := ../../../
+include $(XEN_ROOT)/tools/Rules.mk
+
+.PHONY: all
+all:
+
+.PHONY: install
+install:
+	$(INSTALL_DIR) -p $(DESTDIR)$(INCLUDEDIR)
+
+
+.PHONY: clean
+clean:
+	@:
diff --git a/tools/blktap2/include/atomicio.h b/tools/blktap2/include/atomicio.h
new file mode 100644
index 0000000000..7eccf206b3
--- /dev/null
+++ b/tools/blktap2/include/atomicio.h
@@ -0,0 +1,33 @@
+/*	$OpenBSD: atomicio.h,v 1.6 2005/05/24 17:32:43 avsm Exp $	*/
+
+/*
+ * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Ensure all of data on socket comes through. f==read || f==vwrite
+ */
+size_t	atomicio(ssize_t (*)(int, void *, size_t), int, void *, size_t);
+
+#define vwrite (ssize_t (*)(int, void *, size_t))write
diff --git a/tools/blktap2/include/blktaplib.h b/tools/blktap2/include/blktaplib.h
new file mode 100644
index 0000000000..1824afa943
--- /dev/null
+++ b/tools/blktap2/include/blktaplib.h
@@ -0,0 +1,249 @@
+/* blktaplib.h
+ *
+ * Blktap library userspace code.
+ *
+ * Copyright (c) 2007, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __BLKTAPLIB_H__
+#define __BLKTAPLIB_H__
+
+#include <syslog.h>
+#include <xenctrl.h>
+#include <xen/io/blkif.h>
+
+#if 1
+#define DPRINTF(_f, _a...) syslog(LOG_INFO, _f, ##_a)
+#else
+#define DPRINTF(_f, _a...) ((void)0)
+#endif
+
+#define EPRINTF(_f, _a...) syslog(LOG_ERR, "tap-err:%s: " _f, __func__, ##_a)
+
+#define BLK_RING_SIZE __RING_SIZE((blkif_sring_t *)0, XC_PAGE_SIZE)
+
+/* size of the extra VMA area to map in attached pages. */
+#define BLKTAP_VMA_PAGES BLK_RING_SIZE
+
+/* blktap IOCTLs: These must correspond with the blktap driver ioctls */
+#define BLKTAP_IOCTL_KICK_FE         1
+#define BLKTAP_IOCTL_KICK_BE         2
+#define BLKTAP_IOCTL_SETMODE         3
+#define BLKTAP_IOCTL_SENDPID	     4
+#define BLKTAP_IOCTL_NEWINTF	     5
+#define BLKTAP_IOCTL_MINOR	     6
+#define BLKTAP_IOCTL_MAJOR	     7
+#define BLKTAP_QUERY_ALLOC_REQS      8
+#define BLKTAP_IOCTL_FREEINTF	     9
+#define BLKTAP_IOCTL_PRINT_IDXS      100 
+#define BLKTAP_IOCTL_BACKDEV_SETUP   200
+
+#define PRIO_SPECIAL_IO             -9999 
+
+/* blktap switching modes: (Set with BLKTAP_IOCTL_SETMODE)             */
+#define BLKTAP_MODE_PASSTHROUGH      0x00000000  /* default            */
+#define BLKTAP_MODE_INTERCEPT_FE     0x00000001
+#define BLKTAP_MODE_INTERCEPT_BE     0x00000002
+
+#define BLKTAP_MODE_INTERPOSE \
+           (BLKTAP_MODE_INTERCEPT_FE | BLKTAP_MODE_INTERCEPT_BE)
+
+static inline int BLKTAP_MODE_VALID(unsigned long arg)
+{
+	return (
+		( arg == BLKTAP_MODE_PASSTHROUGH  ) ||
+		( arg == BLKTAP_MODE_INTERCEPT_FE ) ||
+		( arg == BLKTAP_MODE_INTERPOSE    ) );
+}
+
+#define MAX_REQUESTS            BLK_RING_SIZE
+
+#define BLKTAP_IOCTL_KICK       1
+#define MAX_PENDING_REQS	BLK_RING_SIZE
+#define BLKTAP_DEV_DIR          "/dev/xen"
+#define BLKTAP_DEV_NAME         "blktap"
+#define BACKDEV_NAME            "backdev"
+#define BLKTAP_DEV_MINOR        0
+#define BLKTAP_CTRL_DIR         "/var/run/tap"
+
+extern int blktap_major;
+
+#define BLKTAP_RING_PAGES       1 /* Front */
+#define BLKTAP_MMAP_REGION_SIZE (BLKTAP_RING_PAGES + MMAP_PAGES)
+
+struct blkif;
+struct blkif_info;
+
+typedef struct {
+	blkif_request_t  req;
+	int              submitting;
+	int              secs_pending;
+        int16_t          status;
+	int              num_retries;
+	struct timeval   last_try;
+} pending_req_t;
+
+typedef struct blkif {
+	domid_t domid;
+	long int handle;
+	
+	long int pdev;
+	long int readonly;
+	
+	enum { DISCONNECTED, DISCONNECTING, CONNECTED } state;
+	
+	struct blkif_ops *ops;
+	struct blkif *hash_next;
+	
+	void *prv;  /* device-specific data */
+	struct blkif_info *info; /*Image parameter passing */
+	pending_req_t pending_list[MAX_REQUESTS];
+	int devnum;
+	int fds[2];
+	int be_id;
+	char *backend_path;
+	int major;
+	int minor;
+	pid_t tappid;
+	int drivertype;
+	uint16_t cookie;
+	int err;
+} blkif_t;
+
+typedef struct blkif_info {
+	char *params;
+	int   readonly;
+	int   storage;
+} blkif_info_t;
+
+typedef struct tapdev_info {
+	int fd;
+	char *mem;
+	blkif_sring_t *sring;
+	blkif_back_ring_t  fe_ring;
+	unsigned long vstart;
+	blkif_t *blkif;
+} tapdev_info_t;
+
+typedef struct domid_translate {
+	unsigned short domid;
+	unsigned short busid;
+} domid_translate_t ;
+
+typedef struct image {
+	unsigned long long size;
+	unsigned long secsize;
+	unsigned int info;
+} image_t;
+
+typedef struct msg_hdr {
+	uint16_t   type;
+	uint16_t   len;
+	uint16_t   drivertype;
+	uint16_t   cookie;
+} msg_hdr_t;
+
+typedef struct msg_params {
+	uint8_t    readonly;
+	int        path_off;
+	int        path_len;
+	int        storage;
+} msg_params_t;
+
+typedef struct msg_newdev {
+	uint8_t     devnum;
+	uint16_t    domid;
+} msg_newdev_t;
+
+typedef struct msg_pid {
+	pid_t     pid;
+} msg_pid_t;
+
+typedef struct msg_cp {
+	int       cp_uuid_off;
+	int       cp_uuid_len;
+	int       cp_drivertype;
+} msg_cp_t;
+
+typedef struct msg_lock {
+	int       ro;
+	int       enforce;
+	int       uuid_off;
+	int       uuid_len;
+} msg_lock_t;
+
+#define READ 0
+#define WRITE 1
+
+/*Control Messages between manager and tapdev*/
+#define CTLMSG_PARAMS          1
+#define CTLMSG_IMG             2
+#define CTLMSG_IMG_FAIL        3
+#define CTLMSG_NEWDEV          4
+#define CTLMSG_NEWDEV_RSP      5
+#define CTLMSG_NEWDEV_FAIL     6
+#define CTLMSG_CLOSE           7
+#define CTLMSG_CLOSE_RSP       8
+#define CTLMSG_PID             9
+#define CTLMSG_PID_RSP         10
+#define CTLMSG_CHECKPOINT      11
+#define CTLMSG_CHECKPOINT_RSP  12
+#define CTLMSG_LOCK            13
+#define CTLMSG_LOCK_RSP        14
+#define CTLMSG_PAUSE           15
+#define CTLMSG_PAUSE_RSP       16
+#define CTLMSG_RESUME          17
+#define CTLMSG_RESUME_RSP      18
+
+#define TAPDISK_STORAGE_TYPE_NFS       1
+#define TAPDISK_STORAGE_TYPE_EXT       2
+#define TAPDISK_STORAGE_TYPE_LVM       3
+#define TAPDISK_STORAGE_TYPE_DEFAULT   TAPDISK_STORAGE_TYPE_EXT
+
+/* Abitrary values, must match the underlying driver... */
+#define MAX_TAP_DEV 256
+
+/* Accessing attached data page mappings */
+#define MMAP_PAGES                                                    \
+    (MAX_PENDING_REQS * BLKIF_MAX_SEGMENTS_PER_REQUEST)
+#define MMAP_VADDR(_vstart,_req,_seg)                                 \
+    ((_vstart) +                                                      \
+     ((_req) * BLKIF_MAX_SEGMENTS_PER_REQUEST * getpagesize()) +      \
+     ((_seg) * getpagesize()))
+
+/* Defines that are only used by library clients */
+
+#ifndef __COMPILING_BLKTAP_LIB
+
+static char *blkif_op_name[] = {
+	[BLKIF_OP_READ]       = "READ",
+	[BLKIF_OP_WRITE]      = "WRITE",
+};
+
+#endif /* __COMPILING_BLKTAP_LIB */
+
+#endif /* __BLKTAPLIB_H__ */
diff --git a/tools/blktap2/include/libvhd-journal.h b/tools/blktap2/include/libvhd-journal.h
new file mode 100644
index 0000000000..2f32ff02ca
--- /dev/null
+++ b/tools/blktap2/include/libvhd-journal.h
@@ -0,0 +1,68 @@
+/* Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#ifndef _VHD_JOURNAL_H_
+#define _VHD_JOURNAL_H_
+
+#include <inttypes.h>
+
+#include "libvhd.h"
+
+#define VHD_JOURNAL_METADATA       0x01
+#define VHD_JOURNAL_DATA           0x02
+
+#define VHD_JOURNAL_HEADER_COOKIE  "vjournal"
+#define VHD_JOURNAL_ENTRY_COOKIE   0xaaaa12344321aaaa
+
+typedef struct vhd_journal_header {
+	char                       cookie[8];
+	uuid_t                     uuid;
+	uint64_t                   vhd_footer_offset;
+	uint32_t                   journal_data_entries;
+	uint32_t                   journal_metadata_entries;
+	uint64_t                   journal_data_offset;
+	uint64_t                   journal_metadata_offset;
+	uint64_t                   journal_eof;
+	char                       pad[448];
+} vhd_journal_header_t;
+
+typedef struct vhd_journal {
+	char                      *jname;
+	int                        jfd;
+	int                        is_block; /* is jfd a block device */
+	vhd_journal_header_t       header;
+	vhd_context_t              vhd;
+} vhd_journal_t;
+
+int vhd_journal_create(vhd_journal_t *, const char *file, const char *jfile);
+int vhd_journal_open(vhd_journal_t *, const char *file, const char *jfile);
+int vhd_journal_add_block(vhd_journal_t *, uint32_t block, char mode);
+int vhd_journal_commit(vhd_journal_t *);
+int vhd_journal_revert(vhd_journal_t *);
+int vhd_journal_close(vhd_journal_t *);
+int vhd_journal_remove(vhd_journal_t *);
+
+#endif
diff --git a/tools/blktap2/include/libvhd.h b/tools/blktap2/include/libvhd.h
new file mode 100644
index 0000000000..b128ebaf38
--- /dev/null
+++ b/tools/blktap2/include/libvhd.h
@@ -0,0 +1,308 @@
+/* Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#ifndef _VHD_LIB_H_
+#define _VHD_LIB_H_
+
+#include <string.h>
+#include <endian.h>
+#include <byteswap.h>
+#include <uuid/uuid.h>
+
+#include "vhd.h"
+
+#if BYTE_ORDER == LITTLE_ENDIAN
+  #define BE16_IN(foo)             (*(foo)) = bswap_16(*(foo))
+  #define BE32_IN(foo)             (*(foo)) = bswap_32(*(foo))
+  #define BE64_IN(foo)             (*(foo)) = bswap_64(*(foo))
+  #define BE16_OUT(foo)            (*(foo)) = bswap_16(*(foo))
+  #define BE32_OUT(foo)            (*(foo)) = bswap_32(*(foo))
+  #define BE64_OUT(foo)            (*(foo)) = bswap_64(*(foo))
+#else
+  #define BE16_IN(foo)
+  #define BE32_IN(foo)
+  #define BE64_IN(foo)
+  #define BE32_OUT(foo)
+  #define BE32_OUT(foo)
+  #define BE64_OUT(foo)
+#endif
+
+#define MIN(a, b)                  (((a) < (b)) ? (a) : (b))
+#define MAX(a, b)                  (((a) > (b)) ? (a) : (b))
+
+#define VHD_MAX_NAME_LEN           1024
+
+#define VHD_BLOCK_SHIFT            21
+#define VHD_BLOCK_SIZE             (1ULL << VHD_BLOCK_SHIFT)
+
+#define UTF_16                     "UTF-16"
+#define UTF_16LE                   "UTF-16LE"
+#define UTF_16BE                   "UTF-16BE"
+
+#define VHD_OPEN_RDONLY            0x00001
+#define VHD_OPEN_RDWR              0x00002
+#define VHD_OPEN_FAST              0x00004
+#define VHD_OPEN_STRICT            0x00008
+#define VHD_OPEN_IGNORE_DISABLED   0x00010
+
+#define VHD_FLAG_CREAT_PARENT_RAW        0x00001
+
+#define vhd_flag_set(word, flag)         ((word) |= (flag))
+#define vhd_flag_clear(word, flag)       ((word) &= ~(flag))
+#define vhd_flag_test(word, flag)        ((word) & (flag))
+
+
+#define ENABLE_FAILURE_TESTING
+#define FAIL_REPARENT_BEGIN        0
+#define FAIL_REPARENT_LOCATOR      1
+#define FAIL_REPARENT_END          2
+#define FAIL_RESIZE_BEGIN          3
+#define FAIL_RESIZE_DATA_MOVED     4
+#define FAIL_RESIZE_METADATA_MOVED 5
+#define FAIL_RESIZE_END            6
+#define NUM_FAIL_TESTS             7
+
+#ifdef ENABLE_FAILURE_TESTING
+#define TEST_FAIL_AT(point) \
+	if (TEST_FAIL[point]) { \
+		printf("Failing at %s\n", ENV_VAR_FAIL[point]); exit(EINVAL); }
+#define TEST_FAIL_EXTERN_VARS              \
+	extern const char* ENV_VAR_FAIL[]; \
+	extern int TEST_FAIL[];
+#else
+#define TEST_FAIL_AT(point)
+#define TEST_FAIL_EXTERN_VARS
+#endif // ENABLE_FAILURE_TESTING
+
+
+static const char                  VHD_POISON_COOKIE[] = "v_poison";
+
+typedef struct hd_ftr              vhd_footer_t;
+typedef struct dd_hdr              vhd_header_t;
+typedef struct vhd_bat             vhd_bat_t;
+typedef struct vhd_batmap          vhd_batmap_t;
+typedef struct dd_batmap_hdr       vhd_batmap_header_t;
+typedef struct prt_loc             vhd_parent_locator_t;
+typedef struct vhd_context         vhd_context_t;
+typedef uint32_t                   vhd_flag_creat_t;
+
+struct vhd_bat {
+	uint32_t                   spb;
+	uint32_t                   entries;
+	uint32_t                  *bat;
+};
+
+struct vhd_batmap {
+	vhd_batmap_header_t        header;
+	char                      *map;
+};
+
+struct vhd_context {
+	int                        fd;
+	char                      *file;
+	int                        oflags;
+	int                        is_block;
+
+	uint32_t                   spb;
+	uint32_t                   bm_secs;
+
+	vhd_header_t               header;
+	vhd_footer_t               footer;
+	vhd_bat_t                  bat;
+	vhd_batmap_t               batmap;
+};
+
+static inline uint32_t
+secs_round_up(uint64_t bytes)
+{
+	return ((bytes + (VHD_SECTOR_SIZE - 1)) >> VHD_SECTOR_SHIFT);
+}
+
+static inline uint32_t
+secs_round_up_no_zero(uint64_t bytes)
+{
+	return (secs_round_up(bytes) ? : 1);
+}
+
+static inline uint64_t
+vhd_sectors_to_bytes(uint64_t sectors)
+{
+	return sectors << VHD_SECTOR_SHIFT;
+}
+
+static inline uint64_t
+vhd_bytes_padded(uint64_t bytes)
+{
+	return vhd_sectors_to_bytes(secs_round_up_no_zero(bytes));
+}
+
+static inline int
+vhd_type_dynamic(vhd_context_t *ctx)
+{
+	return (ctx->footer.type == HD_TYPE_DYNAMIC ||
+		ctx->footer.type == HD_TYPE_DIFF);
+}
+
+static inline int
+vhd_creator_tapdisk(vhd_context_t *ctx)
+{
+	return !strncmp(ctx->footer.crtr_app, "tap", 3);
+}
+
+static inline int
+vhd_disabled(vhd_context_t *ctx)
+{
+	return (!memcmp(ctx->footer.cookie,
+			VHD_POISON_COOKIE, sizeof(ctx->footer.cookie)));
+}
+
+static inline size_t
+vhd_parent_locator_size(vhd_parent_locator_t *loc)
+{
+	/*
+	 * MICROSOFT_COMPAT
+	 * data_space *should* be in sectors,
+	 * but sometimes we find it in bytes
+	 */
+	if (loc->data_space < 512)
+		return vhd_sectors_to_bytes(loc->data_space);
+	else if (loc->data_space % 512 == 0)
+		return loc->data_space;
+	else
+		return 0;
+}
+
+static inline int
+vhd_parent_raw(vhd_context_t *ctx)
+{
+	return uuid_is_null(ctx->header.prt_uuid);
+}
+
+void libvhd_set_log_level(int);
+
+int vhd_test_file_fixed(const char *, int *);
+
+uint32_t vhd_time(time_t time);
+size_t vhd_time_to_string(uint32_t timestamp, char *target);
+uint32_t vhd_chs(uint64_t size);
+
+uint32_t vhd_checksum_footer(vhd_footer_t *);
+uint32_t vhd_checksum_header(vhd_header_t *);
+uint32_t vhd_checksum_batmap(vhd_batmap_t *);
+
+void vhd_footer_in(vhd_footer_t *);
+void vhd_footer_out(vhd_footer_t *);
+void vhd_header_in(vhd_header_t *);
+void vhd_header_out(vhd_header_t *);
+void vhd_bat_in(vhd_bat_t *);
+void vhd_bat_out(vhd_bat_t *);
+void vhd_batmap_header_in(vhd_batmap_t *);
+void vhd_batmap_header_out(vhd_batmap_t *);
+
+int vhd_validate_footer(vhd_footer_t *footer);
+int vhd_validate_header(vhd_header_t *header);
+int vhd_validate_batmap_header(vhd_batmap_t *batmap);
+int vhd_validate_batmap(vhd_batmap_t *batmap);
+int vhd_validate_platform_code(uint32_t code);
+
+int vhd_open(vhd_context_t *, const char *file, int flags);
+void vhd_close(vhd_context_t *);
+int vhd_create(const char *name, uint64_t bytes, int type, vhd_flag_creat_t);
+/* vhd_snapshot: the bytes parameter is optional and can be 0 if the snapshot 
+ * is to have the same size as the (first non-empty) parent */
+int vhd_snapshot(const char *snapshot, uint64_t bytes, const char *parent,
+		vhd_flag_creat_t);
+
+int vhd_hidden(vhd_context_t *, int *);
+int vhd_chain_depth(vhd_context_t *, int *);
+
+off64_t vhd_position(vhd_context_t *);
+int vhd_seek(vhd_context_t *, off64_t, int);
+int vhd_read(vhd_context_t *, void *, size_t);
+int vhd_write(vhd_context_t *, void *, size_t);
+
+int vhd_offset(vhd_context_t *, uint32_t, uint32_t *);
+
+int vhd_end_of_headers(vhd_context_t *ctx, off64_t *off);
+int vhd_end_of_data(vhd_context_t *ctx, off64_t *off);
+int vhd_batmap_header_offset(vhd_context_t *ctx, off64_t *off);
+
+int vhd_get_header(vhd_context_t *);
+int vhd_get_footer(vhd_context_t *);
+int vhd_get_bat(vhd_context_t *);
+int vhd_get_batmap(vhd_context_t *);
+
+void vhd_put_header(vhd_context_t *);
+void vhd_put_footer(vhd_context_t *);
+void vhd_put_bat(vhd_context_t *);
+void vhd_put_batmap(vhd_context_t *);
+
+int vhd_has_batmap(vhd_context_t *);
+int vhd_batmap_test(vhd_context_t *, vhd_batmap_t *, uint32_t);
+void vhd_batmap_set(vhd_context_t *, vhd_batmap_t *, uint32_t);
+void vhd_batmap_clear(vhd_context_t *, vhd_batmap_t *, uint32_t);
+
+int vhd_get_phys_size(vhd_context_t *, off64_t *);
+int vhd_set_phys_size(vhd_context_t *, off64_t);
+
+int vhd_bitmap_test(vhd_context_t *, char *, uint32_t);
+void vhd_bitmap_set(vhd_context_t *, char *, uint32_t);
+void vhd_bitmap_clear(vhd_context_t *, char *, uint32_t);
+
+int vhd_parent_locator_count(vhd_context_t *);
+int vhd_parent_locator_get(vhd_context_t *, char **);
+int vhd_parent_locator_read(vhd_context_t *, vhd_parent_locator_t *, char **);
+int vhd_find_parent(vhd_context_t *, const char *, char **);
+int vhd_parent_locator_write_at(vhd_context_t *, const char *,
+				off64_t, uint32_t, size_t,
+				vhd_parent_locator_t *);
+
+int vhd_header_decode_parent(vhd_context_t *, vhd_header_t *, char **);
+int vhd_change_parent(vhd_context_t *, char *parent_path, int raw);
+
+int vhd_read_footer(vhd_context_t *, vhd_footer_t *);
+int vhd_read_footer_at(vhd_context_t *, vhd_footer_t *, off64_t);
+int vhd_read_footer_strict(vhd_context_t *, vhd_footer_t *);
+int vhd_read_header(vhd_context_t *, vhd_header_t *);
+int vhd_read_header_at(vhd_context_t *, vhd_header_t *, off64_t);
+int vhd_read_bat(vhd_context_t *, vhd_bat_t *);
+int vhd_read_batmap(vhd_context_t *, vhd_batmap_t *);
+int vhd_read_bitmap(vhd_context_t *, uint32_t block, char **bufp);
+int vhd_read_block(vhd_context_t *, uint32_t block, char **bufp);
+
+int vhd_write_footer(vhd_context_t *, vhd_footer_t *);
+int vhd_write_footer_at(vhd_context_t *, vhd_footer_t *, off64_t);
+int vhd_write_header(vhd_context_t *, vhd_header_t *);
+int vhd_write_header_at(vhd_context_t *, vhd_header_t *, off64_t);
+int vhd_write_bat(vhd_context_t *, vhd_bat_t *);
+int vhd_write_batmap(vhd_context_t *, vhd_batmap_t *);
+int vhd_write_bitmap(vhd_context_t *, uint32_t block, char *bitmap);
+int vhd_write_block(vhd_context_t *, uint32_t block, char *data);
+
+int vhd_io_read(vhd_context_t *, char *, uint64_t, uint32_t);
+int vhd_io_write(vhd_context_t *, char *, uint64_t, uint32_t);
+
+#endif
diff --git a/tools/blktap2/include/list.h b/tools/blktap2/include/list.h
new file mode 100644
index 0000000000..03a524be01
--- /dev/null
+++ b/tools/blktap2/include/list.h
@@ -0,0 +1,93 @@
+/*
+ * list.h
+ * 
+ * This is a subset of linux's list.h intended to be used in user-space.
+ * 
+ */
+
+#ifndef __LIST_H__
+#define __LIST_H__
+
+#define LIST_POISON1  ((void *) 0x00100100)
+#define LIST_POISON2  ((void *) 0x00200200)
+
+struct list_head {
+        struct list_head *next, *prev;
+};
+ 
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+ 
+#define LIST_HEAD(name) \
+        struct list_head name = LIST_HEAD_INIT(name)
+
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+	list->next = list;
+	list->prev = list;
+}
+
+static inline void __list_add(struct list_head *new,
+                              struct list_head *prev,
+                              struct list_head *next)
+{
+        next->prev = new;
+        new->next = next;
+        new->prev = prev;
+        prev->next = new;
+}
+
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+        __list_add(new, head, head->next);
+}
+
+static inline void list_add_tail(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head->prev, head);
+}
+
+static inline void __list_del(struct list_head * prev, struct list_head * next)
+{
+        next->prev = prev;
+        prev->next = next;
+}
+
+static inline void list_del(struct list_head *entry)
+{
+        __list_del(entry->prev, entry->next);
+        entry->next = LIST_POISON1;
+        entry->prev = LIST_POISON2;
+}
+
+static inline void list_del_init(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+	INIT_LIST_HEAD(entry);
+}
+
+static inline int list_empty(const struct list_head *head)
+{
+	return head->next == head;
+}
+
+static inline int list_is_last(const struct list_head *list,
+			       const struct list_head *head)
+{
+	return list->next == head;
+}
+
+#define list_entry(ptr, type, member)                                   \
+        ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
+
+#define list_for_each_entry(pos, head, member)                          \
+        for (pos = list_entry((head)->next, typeof(*pos), member);      \
+             &pos->member != (head);                                    \
+             pos = list_entry(pos->member.next, typeof(*pos), member))
+
+#define list_for_each_entry_safe(pos, n, head, member)			\
+	for (pos = list_entry((head)->next, typeof(*pos), member),	\
+	       n = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head); 					\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+#endif /* __LIST_H__ */
diff --git a/tools/blktap2/include/lvm-util.h b/tools/blktap2/include/lvm-util.h
new file mode 100644
index 0000000000..95f3320334
--- /dev/null
+++ b/tools/blktap2/include/lvm-util.h
@@ -0,0 +1,71 @@
+/* 
+ * Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef _LVM_UTIL_H_
+#define _LVM_UTIL_H_
+
+#include <inttypes.h>
+
+#define MAX_NAME_SIZE            256
+
+#define LVM_SEG_TYPE_LINEAR      1
+#define LVM_SEG_TYPE_UNKNOWN     2
+
+struct lv_segment {
+	uint8_t                  type;
+	char                     device[MAX_NAME_SIZE];
+	uint64_t                 pe_start;
+	uint64_t                 pe_size;
+};
+
+struct lv {
+	char                     name[MAX_NAME_SIZE];
+	uint64_t                 size;
+	uint32_t                 segments;
+	struct lv_segment        first_segment;
+};
+
+struct pv {
+	char                     name[MAX_NAME_SIZE];
+	uint64_t                 start;
+};
+
+struct vg {
+	char                     name[MAX_NAME_SIZE];
+	uint64_t                 extent_size;
+
+	int                      pv_cnt;
+	struct pv               *pvs;
+
+	int                      lv_cnt;
+	struct lv               *lvs;
+};
+
+int lvm_scan_vg(const char *vg_name, struct vg *vg);
+void lvm_free_vg(struct vg *vg);
+
+#endif
diff --git a/tools/blktap2/include/relative-path.h b/tools/blktap2/include/relative-path.h
new file mode 100644
index 0000000000..d78f94d023
--- /dev/null
+++ b/tools/blktap2/include/relative-path.h
@@ -0,0 +1,43 @@
+/* Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#ifndef _RELATIVE_PATH_H_
+#define _RELATIVE_PATH_H_
+
+#include <syslog.h>
+
+#define DELIMITER    '/'
+#define MAX_NAME_LEN 1000
+
+#define EPRINTF(_f, _a...) syslog(LOG_ERR, "tap-err:%s: " _f, __func__, ##_a)
+
+/*
+ * returns a relative path from @src to @dest
+ * result should be freed
+ */
+char *relative_path_to(char *src, char *dest, int *err);
+
+#endif
diff --git a/tools/blktap2/include/tapdisk-message.h b/tools/blktap2/include/tapdisk-message.h
new file mode 100644
index 0000000000..1a86dcb6a3
--- /dev/null
+++ b/tools/blktap2/include/tapdisk-message.h
@@ -0,0 +1,141 @@
+/* Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#ifndef _TAPDISK_MESSAGE_H_
+#define _TAPDISK_MESSAGE_H_
+
+#include <inttypes.h>
+
+#define TAPDISK_MESSAGE_MAX_PATH_LENGTH  256
+#define TAPDISK_MESSAGE_STRING_LENGTH    256
+
+#define TAPDISK_MESSAGE_FLAG_SHARED      0x01
+#define TAPDISK_MESSAGE_FLAG_RDONLY      0x02
+#define TAPDISK_MESSAGE_FLAG_ADD_CACHE   0x04
+#define TAPDISK_MESSAGE_FLAG_VHD_INDEX   0x08
+#define TAPDISK_MESSAGE_FLAG_LOG_DIRTY   0x10
+
+typedef struct tapdisk_message           tapdisk_message_t;
+typedef uint8_t                          tapdisk_message_flag_t;
+typedef struct tapdisk_message_image     tapdisk_message_image_t;
+typedef struct tapdisk_message_params    tapdisk_message_params_t;
+typedef struct tapdisk_message_string    tapdisk_message_string_t;
+
+struct tapdisk_message_params {
+	tapdisk_message_flag_t           flags;
+	
+	uint8_t                          storage;
+	uint32_t                         devnum;
+	uint32_t                         domid;
+	uint16_t                         path_len;
+	char                             path[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
+};
+
+struct tapdisk_message_image {
+	uint64_t                         sectors;
+	uint32_t                         sector_size;
+	uint32_t                         info;
+};
+
+struct tapdisk_message_string {
+	char                             text[TAPDISK_MESSAGE_STRING_LENGTH];
+};
+
+struct tapdisk_message {
+	uint16_t                         type;
+	uint16_t                         cookie;
+	uint16_t                         drivertype;
+
+	union {
+		pid_t                    tapdisk_pid;
+		tapdisk_message_image_t  image;
+		tapdisk_message_params_t params;
+		tapdisk_message_string_t string;
+	} u;
+};
+
+enum tapdisk_message_id {
+	TAPDISK_MESSAGE_ERROR = 1,
+	TAPDISK_MESSAGE_RUNTIME_ERROR,
+	TAPDISK_MESSAGE_PID,
+	TAPDISK_MESSAGE_PID_RSP,
+	TAPDISK_MESSAGE_OPEN,
+	TAPDISK_MESSAGE_OPEN_RSP,
+	TAPDISK_MESSAGE_PAUSE,
+	TAPDISK_MESSAGE_PAUSE_RSP,
+	TAPDISK_MESSAGE_RESUME,
+	TAPDISK_MESSAGE_RESUME_RSP,
+	TAPDISK_MESSAGE_CLOSE,
+	TAPDISK_MESSAGE_CLOSE_RSP,
+	TAPDISK_MESSAGE_EXIT,
+};
+
+static inline char *
+tapdisk_message_name(enum tapdisk_message_id id)
+{
+	switch (id) {
+	case TAPDISK_MESSAGE_ERROR:
+		return "error";
+
+	case TAPDISK_MESSAGE_PID:
+		return "pid";
+
+	case TAPDISK_MESSAGE_PID_RSP:
+		return "pid response";
+
+	case TAPDISK_MESSAGE_OPEN:
+		return "open";
+
+	case TAPDISK_MESSAGE_OPEN_RSP:
+		return "open response";
+
+	case TAPDISK_MESSAGE_PAUSE:
+		return "pause";
+
+	case TAPDISK_MESSAGE_PAUSE_RSP:
+		return "pause response";
+
+	case TAPDISK_MESSAGE_RESUME:
+		return "resume";
+
+	case TAPDISK_MESSAGE_RESUME_RSP:
+		return "resume response";
+
+	case TAPDISK_MESSAGE_CLOSE:
+		return "close";
+
+	case TAPDISK_MESSAGE_CLOSE_RSP:
+		return "close response";
+
+	case TAPDISK_MESSAGE_EXIT:
+		return "exit";
+
+	default:
+		return "unknown";
+	}
+}
+
+#endif
diff --git a/tools/blktap2/include/vhd-util.h b/tools/blktap2/include/vhd-util.h
new file mode 100644
index 0000000000..11f077e2bf
--- /dev/null
+++ b/tools/blktap2/include/vhd-util.h
@@ -0,0 +1,44 @@
+/* Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#ifndef _VHD_UTIL_H_
+#define _VHD_UTIL_H_
+
+int vhd_util_create(int argc, char **argv);
+int vhd_util_snapshot(int argc, char **argv);
+int vhd_util_query(int argc, char **argv);
+int vhd_util_read(int argc, char **argv);
+int vhd_util_set_field(int argc, char **argv);
+int vhd_util_repair(int argc, char **argv);
+int vhd_util_fill(int argc, char **argv);
+int vhd_util_resize(int argc, char **argv);
+int vhd_util_coalesce(int argc, char **argv);
+int vhd_util_modify(int argc, char **argv);
+int vhd_util_scan(int argc, char **argv);
+int vhd_util_check(int argc, char **argv);
+int vhd_util_revert(int argc, char **argv);
+
+#endif
diff --git a/tools/blktap2/include/vhd.h b/tools/blktap2/include/vhd.h
new file mode 100644
index 0000000000..4da5f86668
--- /dev/null
+++ b/tools/blktap2/include/vhd.h
@@ -0,0 +1,221 @@
+/* Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#ifndef __VHD_H__
+#define __VHD_H__
+
+#include <asm/types.h>
+#include <uuid/uuid.h>
+#include <inttypes.h>
+
+typedef uint32_t u32;
+typedef uint64_t u64;
+
+#define DEBUG 1
+
+/* ---------------------------------------------------------------------- */
+/* General definitions.                                                   */
+/* ---------------------------------------------------------------------- */
+
+#define VHD_SECTOR_SIZE  512
+#define VHD_SECTOR_SHIFT   9
+
+/* ---------------------------------------------------------------------- */
+/* This is the generic disk footer, used by all disks.                    */
+/* ---------------------------------------------------------------------- */
+
+struct hd_ftr {
+  char   cookie[8];       /* Identifies original creator of the disk      */
+  u32    features;        /* Feature Support -- see below                 */
+  u32    ff_version;      /* (major,minor) version of disk file           */
+  u64    data_offset;     /* Abs. offset from SOF to next structure       */
+  u32    timestamp;       /* Creation time.  secs since 1/1/2000GMT       */
+  char   crtr_app[4];     /* Creator application                          */
+  u32    crtr_ver;        /* Creator version (major,minor)                */
+  u32    crtr_os;         /* Creator host OS                              */
+  u64    orig_size;       /* Size at creation (bytes)                     */
+  u64    curr_size;       /* Current size of disk (bytes)                 */
+  u32    geometry;        /* Disk geometry                                */
+  u32    type;            /* Disk type                                    */
+  u32    checksum;        /* 1's comp sum of this struct.                 */
+  uuid_t uuid;            /* Unique disk ID, used for naming parents      */
+  char   saved;           /* one-bit -- is this disk/VM in a saved state? */
+  char   hidden;          /* tapdisk-specific field: is this vdi hidden?  */
+  char   reserved[426];   /* padding                                      */
+};
+
+/* VHD cookie string. */
+static const char HD_COOKIE[9]  =  "conectix";
+
+/* Feature fields in hd_ftr */
+#define HD_NO_FEATURES     0x00000000
+#define HD_TEMPORARY       0x00000001 /* disk can be deleted on shutdown */
+#define HD_RESERVED        0x00000002 /* NOTE: must always be set        */
+
+/* Version field in hd_ftr */
+#define HD_FF_VERSION      0x00010000
+
+/* Known creator OS type fields in hd_ftr.crtr_os */
+#define HD_CR_OS_WINDOWS   0x5769326B /* (Wi2k) */
+#define HD_CR_OS_MACINTOSH 0x4D616320 /* (Mac ) */
+
+/*
+ * version 0.1:  little endian bitmaps
+ * version 1.1:  big endian bitmaps; batmap
+ * version 1.2:  libvhd
+ * version 1.3:  batmap version bump to 1.2
+ */
+#define VHD_VERSION(major, minor)  (((major) << 16) | ((minor) & 0x0000FFFF))
+#define VHD_CURRENT_VERSION        VHD_VERSION(1, 3)
+
+/* Disk geometry accessor macros. */
+/* Geometry is a triple of (cylinders (2 bytes), tracks (1 byte), and 
+ * secotrs-per-track (1 byte)) 
+ */
+#define GEOM_GET_CYLS(_g)  (((_g) >> 16) & 0xffff)
+#define GEOM_GET_HEADS(_g) (((_g) >> 8)  & 0xff)
+#define GEOM_GET_SPT(_g)   ((_g) & 0xff)
+
+#define GEOM_ENCODE(_c, _h, _s) (((_c) << 16) | ((_h) << 8) | (_s))
+
+/* type field in hd_ftr */
+#define HD_TYPE_NONE       0
+#define HD_TYPE_FIXED      2  /* fixed-allocation disk */
+#define HD_TYPE_DYNAMIC    3  /* dynamic disk */
+#define HD_TYPE_DIFF       4  /* differencing disk */
+
+/* String table for hd.type */
+static const char *HD_TYPE_STR[7] = {
+        "None",                    /* 0 */
+        "Reserved (deprecated)",   /* 1 */
+        "Fixed hard disk",         /* 2 */
+        "Dynamic hard disk",       /* 3 */
+        "Differencing hard disk",  /* 4 */
+        "Reserved (deprecated)",   /* 5 */
+        "Reserved (deprecated)"    /* 6 */
+};
+
+#define HD_TYPE_MAX 6
+
+struct prt_loc {
+  u32    code;            /* Platform code -- see defines below.          */
+  u32    data_space;      /* Number of 512-byte sectors to store locator  */
+  u32    data_len;        /* Actual length of parent locator in bytes     */
+  u32    res;             /* Must be zero                                 */
+  u64    data_offset;     /* Absolute offset of locator data (bytes)      */
+};
+
+/* Platform Codes */
+#define PLAT_CODE_NONE  0x0
+#define PLAT_CODE_WI2R  0x57693272  /* deprecated                         */
+#define PLAT_CODE_WI2K  0x5769326B  /* deprecated                         */
+#define PLAT_CODE_W2RU  0x57327275  /* Windows relative path (UTF-16)     */
+#define PLAT_CODE_W2KU  0x57326B75  /* Windows absolute path (UTF-16)     */
+#define PLAT_CODE_MAC   0x4D616320  /* MacOS alias stored as a blob.      */
+#define PLAT_CODE_MACX  0x4D616358  /* File URL (UTF-8), see RFC 2396.    */
+
+/* ---------------------------------------------------------------------- */
+/* This is the dynamic disk header.                                       */
+/* ---------------------------------------------------------------------- */
+
+struct dd_hdr {
+  char   cookie[8];       /* Should contain "cxsparse"                    */
+  u64    data_offset;     /* Byte offset of next record. (Unused) 0xffs   */
+  u64    table_offset;    /* Absolute offset to the BAT.                  */
+  u32    hdr_ver;         /* Version of the dd_hdr (major,minor)          */
+  u32    max_bat_size;    /* Maximum number of entries in the BAT         */
+  u32    block_size;      /* Block size in bytes. Must be power of 2.     */
+  u32    checksum;        /* Header checksum.  1's comp of all fields.    */
+  uuid_t prt_uuid;        /* ID of the parent disk.                       */
+  u32    prt_ts;          /* Modification time of the parent disk         */
+  u32    res1;            /* Reserved.                                    */
+  char   prt_name[512];   /* Parent unicode name.                         */
+  struct prt_loc loc[8];  /* Parent locator entries.                      */
+  char   res2[256];       /* Reserved.                                    */
+};
+
+/* VHD cookie string. */
+static const char DD_COOKIE[9]  =  "cxsparse";
+
+/* Version field in hd_ftr */
+#define DD_VERSION 0x00010000
+
+/* Default blocksize is 2 meg. */
+#define DD_BLOCKSIZE_DEFAULT 0x00200000
+
+#define DD_BLK_UNUSED 0xFFFFFFFF
+
+struct dd_batmap_hdr {
+  char   cookie[8];       /* should contain "tdbatmap"                    */
+  u64    batmap_offset;   /* byte offset to batmap                        */
+  u32    batmap_size;     /* batmap size in sectors                       */
+  u32    batmap_version;  /* version of batmap                            */
+  u32    checksum;        /* batmap checksum -- 1's complement of batmap  */
+};
+
+static const char VHD_BATMAP_COOKIE[9] = "tdbatmap";
+
+/*
+ * version 1.1: signed char checksum
+ */
+#define VHD_BATMAP_VERSION(major, minor)  (((major) << 16) | ((minor) & 0x0000FFFF))
+#define VHD_BATMAP_CURRENT_VERSION        VHD_BATMAP_VERSION(1, 2)
+
+/* Layout of a dynamic disk:
+ *
+ * +-------------------------------------------------+
+ * | Mirror image of HD footer (hd_ftr) (512 bytes)  |
+ * +-------------------------------------------------+
+ * | Sparse drive header (dd_hdr) (1024 bytes)       |
+ * +-------------------------------------------------+
+ * | BAT (Block allocation table)                    |
+ * |   - Array of absolute sector offsets into the   |
+ * |     file (u32).                                 |
+ * |   - Rounded up to a sector boundary.            |
+ * |   - Unused entries are marked as 0xFFFFFFFF     |
+ * |   - max entries in dd_hdr->max_bat_size         |
+ * +-------------------------------------------------+
+ * | Data Block 0                                    |
+ * | Bitmap (padded to 512 byte sector boundary)     |
+ * |   - each bit indicates whether the associated   |
+ * |     sector within this block is used.           |
+ * | Data                                            |
+ * |   - power-of-two multiple of sectors.           |
+ * |   - default 2MB (4096 * 512)                    |
+ * |   - Any entries with zero in bitmap should be   |
+ * |     zero on disk                                |
+ * +-------------------------------------------------+
+ * | Data Block 1                                    |
+ * +-------------------------------------------------+
+ * | ...                                             |
+ * +-------------------------------------------------+
+ * | Data Block n                                    |
+ * +-------------------------------------------------+
+ * | HD Footer (511 bytes)                           |
+ * +-------------------------------------------------+
+ */
+
+#endif