diff --git a/libqblock/libqblock.h b/libqblock/libqblock.h
new file mode 100644
index 0000000..33381d1
--- /dev/null
+++ b/libqblock/libqblock.h
@@ -0,0 +1,550 @@
+/*
+ * QEMU block layer library
+ *
+ * Copyright IBM, Corp. 2012
+ *
+ * Authors:
+ *  Wenchao Xia   <xiawenc@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#ifndef LIBQBLOCK_H
+#define LIBQBLOCK_H
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#define QB_ERR_MEM_ERR (-1)
+#define QB_ERR_INTERNAL_ERR (-2)
+#define QB_ERR_INVALID_PARAM (-3)
+
+/* this library is designed around this core struct. */
+struct QBlockState;
+
+/* every thread would have a broker. */
+struct QBroker;
+
+/**
+ * libqblock_init: Initialize the library
+ */
+void libqblock_init(void);
+
+/**
+ * qb_broker_new: allocate a new broker
+ *
+ * Broker is used to pass operation to libqblock, and got feed back from it.
+ *
+ * Returns 0 on success, negative value on fail.
+ *
+ * @broker: used to receive the created struct.
+ */
+int qb_broker_new(struct QBroker **broker);
+
+/**
+ * qb_broker_delete: delete broker
+ *
+ * Broker will be freed and set to NULL.
+ *
+ * @broker: operation broker to be deleted.
+ */
+void qb_broker_delete(struct QBroker **broker);
+
+/**
+ * qb_state_new: allocate a new QBloctState struct
+ *
+ * Following qblock action were based on this struct
+ *
+ * Returns 0 if succeed, negative value on fail.
+ *
+ * @broker: operation broker.
+ * @qbs: used to receive the created struct.
+ */
+int qb_state_new(struct QBroker *broker,
+                 struct QBlockState **qbs);
+
+/**
+ * qb_state_delete: free a QBloctState struct
+ *
+ * if it is opened, a qb_close must be called before free.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to the struct's pointer.
+ */
+void qb_state_delete(struct QBroker *broker,
+                     struct QBlockState **qbs);
+
+
+/* flag used in open and create */
+#define LIBQBLOCK_O_RDWR        0x0002
+/* do not use the host page cache */
+#define LIBQBLOCK_O_NOCACHE     0x0020
+/* use write-back caching */
+#define LIBQBLOCK_O_CACHE_WB    0x0040
+/* don't open the backing file */
+#define LIBQBLOCK_O_NO_BACKING  0x0100
+/* disable flushing on this disk */
+#define LIBQBLOCK_O_NO_FLUSH    0x0200
+
+#define LIBQBLOCK_O_CACHE_MASK \
+   (LIBQBLOCK_O_NOCACHE | LIBQBLOCK_O_CACHE_WB | LIBQBLOCK_O_NO_FLUSH)
+
+#define LIBQBLOCK_O_VALID_MASK \
+   (LIBQBLOCK_O_RDWR | LIBQBLOCK_O_NOCACHE | LIBQBLOCK_O_CACHE_WB | \
+    LIBQBLOCK_O_NO_BACKING | LIBQBLOCK_O_NO_FLUSH)
+
+enum QBlockProtocol {
+    QB_PROTO_NONE = 0,
+    QB_PROTO_FILE,
+    QB_PROTO_MAX
+};
+
+enum QBlockFormat {
+    QB_FMT_NONE = 0,
+    QB_FMT_COW,
+    QB_FMT_QED,
+    QB_FMT_QCOW,
+    QB_FMT_QCOW2,
+    QB_FMT_RAW,
+    QB_FMT_RBD,
+    QB_FMT_SHEEPDOG,
+    QB_FMT_VDI,
+    QB_FMT_VMDK,
+    QB_FMT_VPC,
+    QB_FMT_MAX
+};
+
+struct QBlockOption_prot_file {
+    char *filename;
+};
+
+union QBlockOption_prot {
+    struct QBlockOption_prot_file o_file;
+};
+
+/**
+ * struct QBlockOptionLoc: contains information about how to find the image
+ *
+ * @prot_type: protocol type, now only support FILE.
+ * @prot_op: protocol related options.
+ */
+struct QBlockOptionLoc {
+    enum QBlockProtocol prot_type;
+    union QBlockOption_prot prot_op;
+    uint8_t reserved[512];
+};
+
+/**
+ * qb_ol_new: create a new struct QBlockOptionLoc.
+ *
+ * return 0 on success, negative on fail.
+ *
+ * @broker: operation broker.
+ * @op: pointer to receive the new created one.
+ */
+int qb_ol_new(struct QBroker *broker,
+              struct QBlockOptionLoc **op);
+
+/**
+ * qb_ol_delete: free a struct QBlockOptionLoc.
+ *
+ * @broker: operation broker.
+ * @op: pointer to the object, *op would be set to NULL.
+ */
+void qb_ol_delete(struct QBroker *broker,
+                  struct QBlockOptionLoc **op);
+
+
+/* format related options */
+struct QBlockOption_fmt_cow {
+    size_t virt_size;
+    struct QBlockOptionLoc backing_loc;
+};
+
+struct QBlockOption_fmt_qed {
+    size_t virt_size;
+    struct QBlockOptionLoc backing_loc;
+    enum QBlockFormat backing_fmt;
+    size_t cluster_size; /* unit is bytes */
+    size_t table_size; /* unit is clusters */
+};
+
+struct QBlockOption_fmt_qcow {
+    size_t virt_size;
+    struct QBlockOptionLoc backing_loc;
+    bool encrypt;
+};
+
+/* "Compatibility level (0.10 or 1.1)" */
+enum QBlockOption_fmt_qcow2_cpt {
+    QBO_FMT_QCOW2_CPT_NONE = 0,
+    QBO_FMT_QCOW2_CPT_V010,
+    QBO_FMT_QCOW2_CPT_V110,
+};
+
+/* off or metadata */
+enum QBlockOption_fmt_qcow2_prealloc {
+    QBO_FMT_QCOW2_PREALLOC_NONE = 0,
+    QBO_FMT_QCOW2_PREALLOC_OFF,
+    QBO_FMT_QCOW2_PREALLOC_METADATA,
+};
+
+struct QBlockOption_fmt_qcow2 {
+    size_t virt_size;
+    struct QBlockOptionLoc backing_loc;
+    enum QBlockFormat backing_fmt;
+    bool encrypt;
+    size_t cluster_size; /* unit is bytes */
+    enum QBlockOption_fmt_qcow2_cpt cpt_lv;
+    enum QBlockOption_fmt_qcow2_prealloc pre_mode;
+};
+
+struct QBlockOption_fmt_raw {
+    size_t virt_size;
+};
+
+struct QBlockOption_fmt_rbd {
+    size_t virt_size;
+    size_t cluster_size;
+};
+
+/* off or full */
+enum QBlockOption_fmt_sheepdog_prealloc {
+    QBO_FMT_SD_PREALLOC_NONE = 0,
+    QBO_FMT_SD_PREALLOC_OFF,
+    QBO_FMT_SD_PREALLOC_FULL,
+};
+
+struct QBlockOption_fmt_sheepdog {
+    size_t virt_size;
+    struct QBlockOptionLoc backing_loc;
+    enum QBlockOption_fmt_sheepdog_prealloc pre_mode;
+};
+
+enum QBlockOption_fmt_vdi_prealloc {
+    QBO_FMT_VDI_PREALLOC_NONE = 0,
+    QBO_FMT_VDI_PREALLOC_FALSE,
+    QBO_FMT_VDI_PREALLOC_TRUE,
+};
+
+struct QBlockOption_fmt_vdi {
+    size_t virt_size;
+    size_t cluster_size;
+    enum QBlockOption_fmt_vdi_prealloc pre_mode;
+};
+
+/* whether compact to vmdk verion 6 */
+enum QBlockOption_fmt_vmdk_cpt {
+    QBO_FMT_VMDK_CPT_NONE = 0,
+    QBO_FMT_VMDK_CPT_VMDKV6_FALSE,
+    QBO_FMT_VMDK_CPT_VMDKV6_TRUE,
+};
+
+/* vmdk flat extent format, values:
+"{monolithicSparse (default) | monolithicFlat | twoGbMaxExtentSparse |
+twoGbMaxExtentFlat | streamOptimized} */
+enum QBlockOption_fmt_vmdk_subfmt {
+    QBO_FMT_VMDK_SUBFMT_MONOLITHIC_NONE = 0,
+    QBO_FMT_VMDK_SUBFMT_MONOLITHIC_SPARSE,
+    QBO_FMT_VMDK_SUBFMT_MONOLITHIC_FLAT,
+    QBO_FMT_VMDK_SUBFMT_TWOGBMAX_EXTENT_SPARSE,
+    QBO_FMT_VMDK_SUBFMT_TWOGBMAX_EXTENT_FLAT,
+    QBO_FMT_VMDK_SUBFMT_STREAM_OPTIMIZED,
+};
+
+struct QBlockOption_fmt_vmdk {
+    size_t virt_size;
+    struct QBlockOptionLoc backing_loc;
+    enum QBlockOption_fmt_vmdk_cpt cpt_lv;
+    enum QBlockOption_fmt_vmdk_subfmt subfmt;
+};
+
+/* "{dynamic (default) | fixed} " */
+enum QBlockOption_fmt_vpc_subfmt {
+    QBO_FMT_VPC_SUBFMT_NONE = 0,
+    QBO_FMT_VPC_SUBFMT_DYNAMIC,
+    QBO_FMT_VPC_SUBFMT_FIXED,
+};
+
+struct QBlockOption_fmt_vpc {
+    size_t virt_size;
+    enum QBlockOption_fmt_vpc_subfmt subfmt;
+};
+
+union QBlockOption_fmt {
+    struct QBlockOption_fmt_cow       o_cow;
+    struct QBlockOption_fmt_qed       o_qed;
+    struct QBlockOption_fmt_qcow      o_qcow;
+    struct QBlockOption_fmt_qcow2     o_qcow2;
+    struct QBlockOption_fmt_raw       o_raw;
+    struct QBlockOption_fmt_rbd       o_rbd;
+    struct QBlockOption_fmt_sheepdog  o_sheepdog;
+    struct QBlockOption_fmt_vdi       o_vdi;
+    struct QBlockOption_fmt_vmdk      o_vmdk;
+    struct QBlockOption_fmt_vpc       o_vpc;
+};
+
+struct QBlockOptionFormat {
+    enum QBlockFormat fmt_type;
+    union QBlockOption_fmt fmt_op;
+    uint8_t reserved[512];
+};
+
+/**
+ * qb_of_new: create a new QBlockOptionFormat structure.
+ *
+ * return 0 on success, negative on fail.
+ *
+ * @broker: operation broker.
+ * @op: pointer that will receive created struct.
+ */
+int qb_of_new(struct QBroker *broker,
+              struct QBlockOptionFormat **op);
+
+/**
+ * qb_of_delete: free QBlockOptionFormat structure.
+ *
+ * @broker: operation broker.
+ * @op: pointer to the struct, *op would be set to NULL.
+ */
+void qb_of_delete(struct QBroker *broker,
+                  struct QBlockOptionFormat **op);
+
+
+/**
+ * qb_open: open a block object.
+ *
+ * return 0 on success, negative on fail.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ * @loc: location options for open, how to find the image.
+ * @fmt: format options, how to extract the data, only valid member now is
+     fmt->fmt_type, set NULL if you want auto discovery the format.
+ * @flag: behavior control flags.
+ */
+int qb_open(struct QBroker *broker,
+            struct QBlockState *qbs,
+            struct QBlockOptionLoc *loc,
+            struct QBlockOptionFormat *fmt,
+            int flag);
+
+/**
+ * qb_close: close a block object.
+ *
+ * qb_flush is automaticlly done inside.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ */
+void qb_close(struct QBroker *broker,
+              struct QBlockState *qbs);
+
+/**
+ * qb_create: create a block image or object.
+ *
+ * Note: Create operation would not open the image automatically.
+ *
+ * return negative on fail, 0 on success.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ * @loc: location options for open, how to find the image.
+ * @fmt: format options, how to extract the data.
+ * @flag: behavior control flags.
+ */
+int qb_create(struct QBroker *broker,
+              struct QBlockState *qbs,
+              struct QBlockOptionLoc *loc,
+              struct QBlockOptionFormat *fmt,
+              int flag);
+
+
+/* sync access */
+/**
+ * qb_read: block sync read.
+ *
+ * return negative on fail, 0 on success.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ * @buf: buffer that receive the content.
+ * @len: length to read.
+ * @offset: offset in the block data.
+ */
+int qb_read(struct QBroker *broker,
+            struct QBlockState *qbs,
+            const void *buf,
+            size_t len,
+            off_t offset);
+/**
+ * qb_write: block sync write.
+ *
+ * return negative on fail, 0 on success.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ * @buf: buffer that receive the content.
+ * @len: length to write.
+ * @offset: offset in the block data.
+ */
+int qb_write(struct QBroker *broker,
+             struct QBlockState *qbs,
+             const void *buf,
+             size_t len,
+             off_t offset);
+
+/**
+ * qb_flush: block sync flush.
+ *
+ * return negative on fail, 0 on success.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ */
+int qb_flush(struct QBroker *broker,
+             struct QBlockState *qbs);
+
+/* AIO */
+/**
+ * QBAioReq: represent the AIO request fired.
+ */
+struct QBAioReq;
+
+/**
+ * QBAioCompFunc: call back function which would be automatically called in
+ * qb_aio_check if a IO complete or cancelled.
+ *
+ * @opaque: opaque data registed.
+ * @ret: io execution result.
+ */
+typedef void QBAioCompFunc(void *opaque, int ret);
+
+/**
+ * qb_aio_write: block async write.
+ *
+ * return negative on fail, 0 on success.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ * @buf: buffer that receive the content.
+ * @len: length to write.
+ * @offset: offset in the block data.
+ * @cb: call back function after io complete, can be NULL.
+ * @cb_opaque: call back opaque data.
+ * @req: pointer to receive new created request, can be NULL.
+ */
+int qb_aio_write(struct QBroker *broker,
+                 struct QBlockState *qbs,
+                 void *buf,
+                 size_t len,
+                 off_t offset,
+                 QBAioCompFunc *cb,
+                 void *cb_opaque,
+                 struct QBAioReq **req);
+
+/**
+ * qb_aio_read: block async read.
+ *
+ * return negative on fail, 0 on success.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ * @buf: buffer that receive the content.
+ * @len: length to write.
+ * @offset: offset in the block data.
+ * @cb: call back function after io complete, can be NULL.
+ * @cb_opaque: call back opaque data.
+ * @req: pointer to receive new created request, can be NULL.
+ */
+int qb_aio_read(struct QBroker *broker,
+                struct QBlockState *qbs,
+                void *buf,
+                size_t len,
+                off_t offset,
+                QBAioCompFunc *cb,
+                void *cb_opaque,
+                struct QBAioReq **req);
+
+/**
+ * qb_aio_check: check if there is aio request completed, if there is, execute
+ *   the registered QBAioCompFunc call back function.
+ *
+ *   return true if there is aio request remains, false if no aio request left,
+ * It never fail. Note the execution sequence of submitted request is not
+ * guarrentted.
+ */
+bool qb_aio_check(struct QBroker *broker);
+
+/* image information */
+/**
+ * QBlockInfoImageStatic: information about the block image.
+ *
+ * @loc: location info.
+ * @fmt_type: format type.
+ * @virt_size: virtual size in bytes.
+ * @backing_loc: backing file location, its type is QB_PROT_NONE if not exist.
+ * @allocated_size: allocated size in bytes, negative if not available.
+ * @encrypt: encrypt flag.
+ */
+struct QBlockInfoImageStatic {
+    struct QBlockOptionLoc loc;
+    enum QBlockFormat fmt_type;
+    size_t virt_size;
+    /* advance info */
+    struct QBlockOptionLoc backing_loc;
+    size_t allocated_size;
+    bool encrypt;
+};
+
+
+/**
+ * qb_get_image_info: get image info.
+ *
+ * return negative on fail, 0 on success.
+ *
+ * @broker: operation broker.
+ * @qbs: pointer to struct QBlockState.
+ * @info: pointer that would receive the information.
+ */
+int qb_info_image_static_get(struct QBroker *broker,
+                             struct QBlockState *qbs,
+                             struct QBlockInfoImageStatic **info);
+
+/**
+ * qb_delete_image_info: free image info.
+ *
+ * @broker: operation broker.
+ * @info: pointer to the information struct.
+ */
+void qb_info_image_static_delete(struct QBroker *broker,
+                                 struct QBlockInfoImageStatic **info);
+
+
+/* error handling */
+/**
+ * qb_error_get_human_str: get human readable erro string.
+ *
+ * return a human readable string.
+ *
+ * @broker: operation broker, must be valid.
+ * @buf: buf to receive the string.
+ * @buf_size: the size of the string buf.
+ */
+void qb_error_get_human_str(struct QBroker *broker,
+                            char *buf, int buf_size);
+
+/**
+ * qb_error_get_errno: get error number, only valid when err_ret is
+ *   QB_ERR_INTERNAL_ERR.
+ *
+ * return negative errno or 0 if last error is not QB_ERR_INTERNAL_ERR.
+ *
+ * @broker: operation broker.
+ */
+int qb_error_get_errno(struct QBroker *broker);
+#endif
