diff --git a/block/Makefile.objs b/block/Makefile.objs
index 2593a2f..8ebda10 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -20,6 +20,7 @@ block-obj-$(CONFIG_RBD) += rbd.o
 block-obj-$(CONFIG_GLUSTERFS) += gluster.o
 block-obj-$(CONFIG_ARCHIPELAGO) += archipelago.o
 block-obj-$(CONFIG_LIBSSH2) += ssh.o
+block-obj-$(CONFIG_VXHS) += vxhs.o
 block-obj-y += accounting.o dirty-bitmap.o
 block-obj-y += write-threshold.o
 
diff --git a/block/vxhs.c b/block/vxhs.c
new file mode 100644
index 0000000..2949561
--- /dev/null
+++ b/block/vxhs.c
@@ -0,0 +1,1460 @@
+/*
+ * QEMU Block driver for Veritas HyperScale (VxHS)
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Please follow QEMU coding guidelines while modifying this file.
+ * The QEMU coding guidelines need to be followed because this driver has
+ * to be submitted to QEMU community in near futute and we want to prevent any
+ * reduce the amount of work at that time.
+ * QEMU coding guidelines can be found at :
+ * http://git.qemu-project.org/?p=qemu.git;a=blob_plain;f=CODING_STYLE;hb=HEAD
+ */
+
+#include "vxhs.h"
+
+/* global variables (per-vm) */
+static QNIOOps          qnioops;
+static GModule          *lib_qemuqnio_handle;
+
+/* qnio client ioapi_ctx */
+static void             *global_qnio_ctx;
+
+/* insure init once */
+static pthread_mutex_t  of_global_ctx_lock;
+
+/* HyperScale Driver Version */
+int vxhs_drv_version = 8895;
+
+/*
+ * Loading QNIO operation from qemuqnio library at run time.
+ * It loads only when first vxhs_open called for a vDisk
+ */
+int vxhs_load_iio_ops(void)
+{
+    int i = 0;
+
+    LibQNIOSymbol qnio_symbols[] = {
+        {"qemu_iio_init",
+                (gpointer *) &qnioops.qemu_iio_init},
+        {"qemu_open_iio_conn",
+                (gpointer *) &qnioops.qemu_open_iio_conn},
+        {"qemu_iio_devopen",
+                (gpointer *) &qnioops.qemu_iio_devopen},
+        {"qemu_iio_devclose",
+                (gpointer *) &qnioops.qemu_iio_devclose},
+        {"qemu_iio_writev",
+                (gpointer *) &qnioops.qemu_iio_writev},
+        {"qemu_iio_readv",
+                (gpointer *) &qnioops.qemu_iio_readv},
+        {"qemu_iio_read",
+                (gpointer *) &qnioops.qemu_iio_read},
+        {"qemu_iio_ioctl",
+                (gpointer *) &qnioops.qemu_iio_ioctl},
+        {"qemu_iio_close",
+                (gpointer *) &qnioops.qemu_iio_close},
+        {"qemu_iio_extract_msg_error",
+                (gpointer *) &qnioops.qemu_iio_extract_msg_error},
+        {"qemu_iio_extract_msg_size",
+                (gpointer *) &qnioops.qemu_iio_extract_msg_size},
+        {"qemu_iio_extract_msg_opcode",
+                (gpointer *) &qnioops.qemu_iio_extract_msg_opcode},
+        {"qemu_initialize_lock",
+                (gpointer *) &qnioops.qemu_initialize_lock},
+        {"qemu_spin_lock",
+                (gpointer *) &qnioops.qemu_spin_lock},
+        {"qemu_spin_unlock",
+                (gpointer *) &qnioops.qemu_spin_unlock},
+        {"qemu_destroy_lock",
+                (gpointer *) &qnioops.qemu_destroy_lock},
+        {NULL}
+    };
+
+    if (!g_module_supported()) {
+        error_report("modules are not supported on this platform: %s",
+                     g_module_error());
+        return -EIO;
+    }
+
+    lib_qemuqnio_handle = g_module_open("libqnioshim.so", 0);
+    if (!lib_qemuqnio_handle) {
+        error_report("error loading libqnioshim.so: %s", g_module_error());
+        return -EIO;
+    }
+
+    g_module_make_resident(lib_qemuqnio_handle);
+    while (qnio_symbols[i].name) {
+        const char *name = qnio_symbols[i].name;
+        if (!g_module_symbol(lib_qemuqnio_handle, name, qnio_symbols[i].addr)) {
+            error_report("%s could not be loaded from qnioops : %s",
+                         name, g_module_error());
+            return -EIO;
+        }
+        ++i;
+    }
+    vxhsDbg("qnio ops loaded\n");
+
+    return 0;
+}
+
+inline void vxhs_inc_acb_segment_count(void *ptr, int count)
+{
+    VXHSAIOCB *acb = (VXHSAIOCB *)ptr;
+    BDRVVXHSState *s = acb->common.bs->opaque;
+
+    VXHS_SPIN_LOCK(s->vdisk_acb_lock);
+    acb->segments += count;
+    VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
+}
+
+inline void vxhs_dec_acb_segment_count(void *ptr, int count)
+{
+    VXHSAIOCB *acb = (VXHSAIOCB *)ptr;
+    BDRVVXHSState *s = acb->common.bs->opaque;
+
+    VXHS_SPIN_LOCK(s->vdisk_acb_lock);
+    acb->segments -= count;
+    VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
+}
+
+inline int vxhs_dec_and_get_acb_segment_count(void *ptr, int count)
+{
+    VXHSAIOCB *acb = (VXHSAIOCB *)ptr;
+    BDRVVXHSState *s = acb->common.bs->opaque;
+    int segcount = 0;
+
+
+    VXHS_SPIN_LOCK(s->vdisk_acb_lock);
+    acb->segments -= count;
+    segcount = acb->segments;
+    VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
+
+    return segcount;
+}
+
+inline void vxhs_set_acb_buffer(void *ptr, void *buffer)
+{
+    VXHSAIOCB *acb = (VXHSAIOCB *)ptr;
+
+    acb->buffer = buffer;
+}
+
+inline void vxhs_inc_vdisk_iocount(void *ptr, uint32_t count)
+{
+    BDRVVXHSState *s = (BDRVVXHSState *)ptr;
+
+    VXHS_SPIN_LOCK(s->vdisk_lock);
+    s->vdisk_aio_count += count;
+    VXHS_SPIN_UNLOCK(s->vdisk_lock);
+}
+
+inline void vxhs_dec_vdisk_iocount(void *ptr, uint32_t count)
+{
+    BDRVVXHSState *s = (BDRVVXHSState *)ptr;
+
+    VXHS_SPIN_LOCK(s->vdisk_lock);
+    s->vdisk_aio_count -= count;
+    VXHS_SPIN_UNLOCK(s->vdisk_lock);
+}
+
+inline uint32_t vxhs_get_vdisk_iocount(void *ptr)
+{
+    BDRVVXHSState *s = (BDRVVXHSState *)ptr;
+    uint32_t count = 0;
+
+    VXHS_SPIN_LOCK(s->vdisk_lock);
+    count = s->vdisk_aio_count;
+    VXHS_SPIN_UNLOCK(s->vdisk_lock);
+
+    return count;
+}
+
+
+/*
+ * All the helper functions required for HyperScale QEMU block driver
+ * If these functions become unmanageable in single file then split it.
+ * Avoiding file proliferage till then.
+ */
+
+char *vxhs_string_iterate(char *p, const char *d, const size_t len)
+{
+    while (p != NULL && *p && memcmp(p, d, len) == 0) {
+        p += len;
+    }
+    return p;
+}
+
+int
+vxhs_tokenize(char **result, char *working, const char *src, const char *delim)
+{
+    int i = 0;
+    char *p = NULL;
+    size_t len = strlen(delim);
+
+    strcpy(working, src);
+    p = working;
+
+    for (result[i] = NULL, p = vxhs_string_iterate(p, delim, len); p != NULL
+        && *p; p = vxhs_string_iterate(p, delim, len)) {
+        result[i++] = p;
+        result[i] = NULL;
+        p = strstr(p, delim);
+    }
+    return i;
+}
+
+void vxhs_iio_callback(uint32_t rfd, uint32_t reason, void *ctx, void *m)
+{
+    VXHSAIOCB *acb = NULL;
+    BDRVVXHSState *s = NULL;
+    int rv = 0;
+    int segcount = 0;
+    uint32_t error = 0;
+    uint32_t opcode = 0;
+
+    assert(m);
+    if (m) {
+        /* TODO: need common get message attrs, not two separate lib calls */
+        error = (*qnioops.qemu_iio_extract_msg_error)(m);
+        opcode = (*qnioops.qemu_iio_extract_msg_opcode)(m);
+    }
+    switch (opcode) {
+    case IRP_READ_REQUEST:
+    case IRP_WRITE_REQUEST:
+
+    /*
+     * ctx is VXHSAIOCB*
+     * ctx is NULL if error is VXERROR_CHANNEL_HUP or reason is IIO_REASON_HUP
+     */
+    if (ctx) {
+        acb = (VXHSAIOCB *)ctx;
+        s = acb->common.bs->opaque;
+    } else {
+        vxhsDbg("ctx is NULL: error %d, reason %d\n",
+                  error, reason);
+        goto out;
+    }
+
+    if (error) {
+        vxhsDbg("Read/Write failed: error %d, reason %d, acb %p, segment %d\n",
+                  error, reason, acb, acb->segments);
+
+        if (reason == IIO_REASON_DONE || reason == IIO_REASON_EVENT) {
+            /*
+             * Storage agent failed while I/O was in progress
+             * Fail over only if the qnio channel dropped, indicating
+             * storage agent failure. Don't fail over in response to other
+             * I/O errors such as disk failure.
+             */
+            if (error == VXERROR_RETRY_ON_SOURCE || error == VXERROR_HUP ||
+                error == VXERROR_CHANNEL_HUP || error == -1) {
+                /*
+                 * Start vDisk IO failover once callback is
+                 * called against all the pending IOs.
+                 * If vDisk has no redundency enabled
+                 * then IO failover routine will mark
+                 * the vDisk failed and fail all the
+                 * AIOs without retry (stateless vDisk)
+                 */
+                VXHS_SPIN_LOCK(s->vdisk_lock);
+                if (!OF_VDISK_IOFAILOVER_IN_PROGRESS(s)) {
+                    OF_VDISK_SET_IOFAILOVER_IN_PROGRESS(s);
+                }
+                /*
+                 * Check if this acb is already queued before.
+                 * It is possible in case if I/Os are submitted
+                 * in multiple segments (QNIO_MAX_IO_SIZE).
+                 */
+                VXHS_SPIN_LOCK(s->vdisk_acb_lock);
+                if (!OF_AIOCB_FLAGS_QUEUED(acb)) {
+                    QSIMPLEQ_INSERT_TAIL(&s->vdisk_aio_retryq,
+                                         acb, retry_entry);
+                    OF_AIOCB_FLAGS_SET_QUEUED(acb);
+                    s->vdisk_aio_retry_qd++;
+                    vxhsDbg("vDisk %s, added acb %p to retry queue(5)\n",
+                              s->vdisk_guid, acb);
+                }
+                segcount = --acb->segments;
+                VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
+                /*
+                 * Decrement AIO count only when callback is called
+                 * against all the segments of aiocb.
+                 */
+                if (segcount == 0 && --s->vdisk_aio_count == 0) {
+                    /*
+                     * Start vDisk I/O failover
+                     */
+                    VXHS_SPIN_UNLOCK(s->vdisk_lock);
+                    /*
+                     * TODO:
+                     * Need to explore further if it is possible to optimize
+                     * the failover operation on Virtual-Machine (global)
+                     * specific rather vDisk specific.
+                     */
+                    vxhs_failover_io(s);
+                    goto out;
+                }
+                VXHS_SPIN_UNLOCK(s->vdisk_lock);
+                goto out;
+            }
+        } else if (reason == IIO_REASON_HUP) {
+            /*
+             * Channel failed, spontaneous notification,
+             * not in response to I/O
+             */
+            vxhsDbg(" QNIO channel failed, no i/o (%d)\n", error);
+            /*
+             * TODO: Start channel failover when no I/O is outstanding
+             */
+            goto out;
+        } else {
+            vxhsDbg(" ALERT: reason = %d , acb = %p, "
+                      "acb->segments = %d, acb->size = %lu Error = %d\n",
+                      reason, acb, acb->segments, acb->size, error);
+        }
+    }
+    /*
+     * Set error into acb if not set. In case if acb is being
+     * submitted in multiple segments then need to set the error
+     * only once.
+     *
+     * Once acb done callback is called for the last segment
+     * then acb->ret return status will be sent back to the
+     * caller.
+     */
+    VXHS_SPIN_LOCK(s->vdisk_acb_lock);
+    if (error && !acb->ret) {
+        acb->ret = error;
+    }
+    --acb->segments;
+    segcount = acb->segments;
+    /*
+     * vxhsDbg(" acb %p segcount %d\n", acb, segcount);
+     */
+    assert(segcount >= 0);
+    VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
+    /*
+     * Check if all the outstanding I/Os are done against acb.
+     * If yes then send signal for AIO completion.
+     */
+    if (segcount == 0) {
+        rv = qemu_write_full(s->fds[VDISK_FD_WRITE], &acb, sizeof(acb));
+        if (rv != sizeof(acb)) {
+            error_report("VXHS AIO completion failed: %s", strerror(errno));
+            abort();
+        }
+    }
+    break;
+
+    case IRP_VDISK_CHECK_IO_FAILOVER_READY:
+        /* ctx is BDRVVXHSState* */
+        assert(ctx);
+        vxhsDbg("async vxhs_iio_callback: IRP_VDISK_CHECK_IO_FAILOVER_READY "
+                  "completed for vdisk %s with error %d\n",
+                  ((BDRVVXHSState *)ctx)->vdisk_guid, error);
+        failover_ioctl_cb(error, ctx);
+        break;
+
+    default:
+        if (reason == IIO_REASON_HUP) {
+            /*
+             * Channel failed, spontaneous notification,
+             * not in response to I/O
+             */
+            vxhsDbg(" QNIO channel failed, no i/o (%d, %d)\n",
+                      error, errno);
+            /*
+             * TODO: Start channel failover when no I/O is outstanding
+             */
+        } else {
+            vxhsDbg("unexpected opcode %d, errno %d\n",
+                      opcode, error);
+        }
+        break;
+    }
+out:
+    return;
+}
+
+void vxhs_complete_aio(VXHSAIOCB *acb, BDRVVXHSState *s)
+{
+    BlockCompletionFunc *cb = acb->common.cb;
+    void *opaque = acb->common.opaque;
+    int ret = 0;
+
+    if (acb->ret != 0) {
+        vxhsDbg("aio failed acb %p ret %ld\n", acb, acb->ret);
+    /*
+     * We mask all the IO errors generically as EIO for upper layers
+     * Right now our IO Manager uses non standard error codes. Instead
+     * of confusing upper layers with incorrect interpretation we are
+     * doing this workaround.
+     */
+        ret = (-EIO);
+    }
+    /*
+     * Copy back contents from stablization buffer into original iovector
+     * before returning the IO
+     */
+    if (acb->buffer != NULL) {
+        qemu_iovec_from_buf(acb->qiov, 0, acb->buffer, acb->qiov->size);
+        free(acb->buffer);
+        acb->buffer = NULL;
+    }
+    vxhs_dec_vdisk_iocount(s, 1);
+    acb->aio_done = VXHS_IO_COMPLETED;
+    qemu_aio_unref(acb);
+    cb(opaque, ret);
+}
+
+/*
+ * This is the HyperScale event handler registered to QEMU.
+ * It invoked when any IO completed and written on pipe
+ * by callback called from QNIO thread context. Then it mark
+ * the AIO as completed and release HyperScale AIO callbacks.
+ */
+void vxhs_aio_event_reader(void *opaque)
+{
+    BDRVVXHSState *s = opaque;
+    ssize_t ret;
+
+    do {
+        char *p = (char *)&s->qnio_event_acb;
+
+        ret = read(s->fds[VDISK_FD_READ], p + s->event_reader_pos,
+                   sizeof(s->qnio_event_acb) - s->event_reader_pos);
+        if (ret > 0) {
+            s->event_reader_pos += ret;
+            if (s->event_reader_pos == sizeof(s->qnio_event_acb)) {
+                s->event_reader_pos = 0;
+                vxhs_complete_aio(s->qnio_event_acb, s);
+            }
+        }
+    } while (ret < 0 && errno == EINTR);
+}
+
+/*
+ * QEMU calls this to check if any pending IO on vDisk
+ * It will wait in loop until all the AIO completed.
+ */
+int vxhs_aio_flush_cb(void *opaque)
+{
+    BDRVVXHSState *s = opaque;
+
+    return vxhs_get_vdisk_iocount(s);
+}
+
+/*
+ * This will be called by QEMU while booting for each vDisks.
+ * bs->opaque will be allocated by QEMU upper block layer before
+ * calling open. It will load all the QNIO operations from
+ * qemuqnio library and call QNIO operation to create channel to
+ * doing IO on vDisk. It parse the URI, get the hostname, vDisk
+ * path and then set HyperScale event handler to QEMU.
+ */
+void *vxhs_initialize(void)
+{
+    void *qnio_ctx = NULL;
+
+    if (vxhs_load_iio_ops() < 0) {
+        vxhsDbg("Could not load the QNIO IO library.\n");
+        return qnio_ctx;
+    }
+
+    qnio_ctx = (*qnioops.qemu_iio_init)(vxhs_iio_callback);
+
+    return qnio_ctx;
+}
+
+void *vxhs_setup_qnio(void)
+{
+    void *qnio_ctx = NULL;
+
+    qnio_ctx = vxhs_initialize();
+
+    if (qnio_ctx != NULL) {
+        vxhsDbg("Context to HyperScale IO manager = %p\n", qnio_ctx);
+    } else {
+        vxhsDbg("Could not initialize the network channel. Bailing out\n");
+    }
+
+    return qnio_ctx;
+}
+
+int vxhs_open_device(const char *vxhs_uri, int *cfd, int *rfd,
+                       BDRVVXHSState *s)
+{
+    char *file_name;
+    char *of_vsa_addr;
+    char **split_filename = (char **)malloc(1024);
+    char *scratch = (char *)malloc(1024);
+    int resilency_count = 0;
+    int ret = 0;
+
+    pthread_mutex_lock(&of_global_ctx_lock);
+    if (global_qnio_ctx == NULL) {
+        global_qnio_ctx = vxhs_setup_qnio();
+        if (global_qnio_ctx == NULL) {
+            vxhsDbg("Error while opening the device. QNIO IO library "
+                      "couldn't be initialized.\n");
+            pthread_mutex_unlock(&of_global_ctx_lock);
+            free(split_filename);
+            free(scratch);
+            return -1;
+        }
+    }
+    pthread_mutex_unlock(&of_global_ctx_lock);
+
+    *cfd = -1;
+
+    of_vsa_addr = (char *) malloc(sizeof(char) * OF_MAX_SERVER_ADDR);
+    if (!of_vsa_addr) {
+        vxhsDbg("Could not allocate memory for file parsing. Bailing out\n");
+        free(split_filename);
+        free(scratch);
+        return -ENOMEM;
+    }
+    memset(of_vsa_addr, 0, OF_MAX_SERVER_ADDR);
+    file_name = (char *) malloc(sizeof(char) * OF_MAX_FILE_LEN);
+    if (!file_name) {
+        vxhsDbg("Could not allocate memory for file parsing. Bailing out\n");
+        free(of_vsa_addr);
+        free(split_filename);
+        free(scratch);
+        return -ENOMEM;
+    }
+    memset(file_name, 0, OF_MAX_FILE_LEN);
+
+    /*
+     * Below steps need to done by all the block driver in QEMU which
+     * support AIO. Need to create pipe for communicating b/w two threads
+     * in different context. And set handler for read event when IO completion
+     * done by non-QEMU context.
+     */
+    vxhsDbg("Original command line : %s\n", vxhs_uri);
+    resilency_count = vxhs_tokenize(split_filename, scratch, vxhs_uri, "%7D");
+    vxhs_build_io_target_list(s, resilency_count, split_filename);
+
+    snprintf(file_name, OF_MAX_FILE_LEN, "%s%s", vdisk_prefix, s->vdisk_guid);
+    snprintf(of_vsa_addr, OF_MAX_SERVER_ADDR, "of://%s:%d",
+             s->vdisk_hostinfo[s->vdisk_cur_host_idx].hostip,
+             s->vdisk_hostinfo[s->vdisk_cur_host_idx].port);
+
+    vxhsDbg("Driver state = %p\n", s);
+    vxhsDbg("Connecting to : %s\n", of_vsa_addr);
+
+    *cfd = (*qnioops.qemu_open_iio_conn)(global_qnio_ctx, of_vsa_addr, 0);
+    if (*cfd < 0) {
+        vxhsDbg("Could not open an QNIO connection to: %s\n", of_vsa_addr);
+        ret = -EIO;
+        goto out;
+    }
+    *rfd = (*qnioops.qemu_iio_devopen)(global_qnio_ctx, *cfd, file_name, 0);
+    s->aio_context = qemu_get_aio_context();
+
+out:
+    /* uri is still in use, cleaned up in close */
+    if (file_name != NULL) {
+        free(file_name);
+    }
+    if (of_vsa_addr != NULL) {
+        free(of_vsa_addr);
+    }
+    free(split_filename);
+    free(scratch);
+    return ret;
+}
+
+int vxhs_create(const char *filename,
+        QemuOpts *options, Error **errp)
+{
+        int ret = 0;
+        int qemu_cfd = 0;
+        int qemu_rfd = 0;
+        BDRVVXHSState s;
+
+        vxhsDbg("vxhs_create: came in to open file = %s\n", filename);
+        ret = vxhs_open_device(filename, &qemu_cfd, &qemu_rfd, &s);
+        vxhsDbg("vxhs_create: s->qnio_cfd = %d , s->rfd = %d\n", qemu_cfd,
+                 qemu_rfd);
+
+        return ret;
+}
+
+static QemuOptsList runtime_opts = {
+    .name = "vxhs",
+    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
+    .desc = {
+        {
+            .name = "filename",
+            .type = QEMU_OPT_STRING,
+            .help = "URI to the Veritas HyperScale image",
+        },
+        { /* end of list */ }
+    },
+};
+
+int vxhs_open(BlockDriverState *bs, QDict *options,
+              int bdrv_flags, Error **errp)
+{
+    BDRVVXHSState *s = bs->opaque;
+    int ret = 0;
+    int qemu_qnio_cfd = 0;
+    int qemu_rfd = 0;
+    QemuOpts *opts;
+    Error *local_err = NULL;
+    const char *vxhs_uri;
+
+    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
+    qemu_opts_absorb_qdict(opts, options, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto out;
+    }
+
+    vxhs_uri = qemu_opt_get(opts, "filename");
+
+    memset(s, 0, sizeof(*s));
+    vxhsDbg("came in to open file = %s\n", vxhs_uri);
+    ret = vxhs_open_device(vxhs_uri, &qemu_qnio_cfd, &qemu_rfd, s);
+    if (ret != 0) {
+        vxhsDbg("Could not open the device. Error = %d\n", ret);
+        return ret;
+    }
+    s->qnio_ctx = global_qnio_ctx;
+    s->vdisk_hostinfo[0].qnio_cfd = qemu_qnio_cfd;
+    s->vdisk_hostinfo[0].vdisk_rfd = qemu_rfd;
+    s->vdisk_size = 0;
+    QSIMPLEQ_INIT(&s->vdisk_aio_retryq);
+
+    vxhsDbg("s->qnio_cfd = %d, s->rfd = %d\n",
+              s->vdisk_hostinfo[0].qnio_cfd,
+              s->vdisk_hostinfo[0].vdisk_rfd);
+    ret = qemu_pipe(s->fds);
+    if (ret < 0) {
+        vxhsDbg("Could not create a pipe for device. bailing out\n");
+        ret = -errno;
+        goto out;
+    }
+    fcntl(s->fds[VDISK_FD_READ], F_SETFL, O_NONBLOCK);
+
+    aio_set_fd_handler(s->aio_context, s->fds[VDISK_FD_READ],
+                       false, vxhs_aio_event_reader, NULL, s);
+
+    /*
+     * Allocate/Initialize the spin-locks.
+     *
+     * NOTE:
+     *      Since spin lock is being allocated
+     *      dynamically hence moving acb struct
+     *      specific lock to BDRVVXHSState
+     *      struct. The reason is very simple,
+     *      we don't want an overhead of spin
+     *      lock dynamic allocation and free
+     *      for every AIO.
+     */
+    s->vdisk_lock = VXHS_SPIN_LOCK_ALLOC;
+    s->vdisk_acb_lock = VXHS_SPIN_LOCK_ALLOC;
+
+    return 0;
+
+out:
+    if (s->vdisk_hostinfo[0].vdisk_rfd >= 0) {
+        qnioops.qemu_iio_devclose(s->qnio_ctx,
+                                 s->vdisk_hostinfo[0].vdisk_rfd);
+    }
+    /* never close qnio_cfd */
+    vxhsDbg("vxhs_open failed (%d)\n", ret);
+    return ret;
+}
+
+static const AIOCBInfo vxhs_aiocb_info = {
+    .aiocb_size = sizeof(VXHSAIOCB)
+};
+
+/*
+ * This is called in QNIO thread context when IO done
+ * on IO Manager and QNIO client received the data or
+ * ACK. It notify another event handler thread running in QEMU context
+ * by writing on the pipe
+ */
+void vxhs_finish_aiocb(ssize_t ret, void *arg)
+{
+    VXHSAIOCB *acb = (VXHSAIOCB *) arg;
+    BlockDriverState *bs = acb->common.bs;
+    BDRVVXHSState *s = bs->opaque;
+    int rv;
+
+    vxhsDbg("finish callback in non-QEMU context... writing on pipe\n");
+    acb->ret = ret;
+    rv = qemu_write_full(s->fds[VDISK_FD_WRITE], &acb, sizeof(acb));
+    if (rv != sizeof(acb)) {
+        error_report("VXHS AIO completion failed: %s",
+                     strerror(errno));
+        abort();
+    }
+}
+
+/*
+ * This allocates QEMU-VXHS callback for each IO
+ * and passed to QNIO. When QNIO completed the work,
+ * it will be passed back through the callback
+ */
+BlockAIOCB *vxhs_aio_rw(BlockDriverState *bs,
+                                int64_t sector_num, QEMUIOVector *qiov,
+                                int nb_sectors,
+                                BlockCompletionFunc *cb,
+                                void *opaque, int iodir)
+{
+    VXHSAIOCB         *acb = NULL;
+    BDRVVXHSState     *s = bs->opaque;
+    size_t              size;
+    uint64_t            offset;
+    int                 iio_flags = 0;
+    int                 ret = 0;
+
+    offset = sector_num * BDRV_SECTOR_SIZE;
+    size = nb_sectors * BDRV_SECTOR_SIZE;
+
+    acb = qemu_aio_get(&vxhs_aiocb_info, bs, cb, opaque);
+    /*
+     * Setup or initialize VXHSAIOCB.
+     * Every single field should be initialized since
+     * acb will be picked up from the slab without
+     * initializing with zero.
+     */
+    acb->io_offset = offset;
+    acb->size = size;
+    acb->ret = 0;
+    acb->flags = 0;
+    acb->aio_done = VXHS_IO_INPROGRESS;
+    acb->segments = 0;
+    acb->buffer = 0;
+    acb->qiov = qiov;
+    acb->direction = iodir;
+
+    VXHS_SPIN_LOCK(s->vdisk_lock);
+    if (OF_VDISK_FAILED(s)) {
+        vxhsDbg("vDisk %s, vDisk device is in failed state "
+                  "iodir = %d size = %lu offset = %lu\n",
+                  s->vdisk_guid, iodir, size, offset);
+        VXHS_SPIN_UNLOCK(s->vdisk_lock);
+        goto errout;
+    }
+    if (OF_VDISK_IOFAILOVER_IN_PROGRESS(s)) {
+        QSIMPLEQ_INSERT_TAIL(&s->vdisk_aio_retryq, acb, retry_entry);
+        s->vdisk_aio_retry_qd++;
+        OF_AIOCB_FLAGS_SET_QUEUED(acb);
+        VXHS_SPIN_UNLOCK(s->vdisk_lock);
+        vxhsDbg("vDisk %s, added acb %p to retry queue(1)\n",
+                  s->vdisk_guid, acb);
+        goto out;
+    }
+    s->vdisk_aio_count++;
+    VXHS_SPIN_UNLOCK(s->vdisk_lock);
+
+    iio_flags = (IIO_FLAG_DONE | IIO_FLAG_ASYNC);
+
+    switch (iodir) {
+    case VDISK_AIO_WRITE:
+            vxhs_inc_acb_segment_count(acb, 1);
+            /*
+             * vxhsDbg("WRITING: opaque = %p size = %lu offset = %lu  "
+             *           "Segments = %d\n", opaque, size,
+             *           sector_num * BDRV_SECTOR_SIZE, acb->segments);
+             */
+            ret = (*qnioops.qemu_iio_writev)(s->qnio_ctx,
+                    s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
+                    qiov->iov, qiov->niov, offset, (void *)acb, iio_flags);
+            /*
+             * vxhsDbg("qemu_iio_writev acb %p ret %d\n", acb, ret);
+             */
+            break;
+    case VDISK_AIO_READ:
+            vxhs_inc_acb_segment_count(acb, 1);
+            /*
+             * vxhsDbg("READING : buf = %p size = %lu offset = %lu "
+             *           "Segments = %d\n", buf, size,
+             *           sector_num * BDRV_SECTOR_SIZE, acb->segments);
+             */
+            ret = (*qnioops.qemu_iio_readv)(s->qnio_ctx,
+                    s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
+                    qiov->iov, qiov->niov, offset, (void *)acb, iio_flags);
+            /*
+             * vxhsDbg("qemu_iio_readv returned %d\n", ret);
+             */
+            break;
+    default:
+            vxhsDbg("Invalid I/O request iodir %d\n", iodir);
+            goto errout;
+    }
+
+    if (ret != 0) {
+        vxhsDbg("IO ERROR (vDisk %s) FOR : Read/Write = %d size = %lu "
+                  "offset = %lu ACB = %p Segments = %d. Error = %d, errno = %d\n",
+                  s->vdisk_guid, iodir, size, offset,
+                  acb, acb->segments, ret, errno);
+        /*
+         * Don't retry I/Os against vDisk having no
+         * redundency or statefull storage on compute
+         *
+         * TODO: Revisit this code path to see if any
+         *       particular error need to be handled.
+         *       At this moment failing the I/O.
+         */
+        VXHS_SPIN_LOCK(s->vdisk_lock);
+        if (s->vdisk_nhosts == 1) {
+            vxhsDbg("vDisk %s, I/O operation failed.\n",
+                      s->vdisk_guid);
+            s->vdisk_aio_count--;
+            vxhs_dec_acb_segment_count(acb, 1);
+            VXHS_SPIN_UNLOCK(s->vdisk_lock);
+            goto errout;
+        }
+        if (OF_VDISK_FAILED(s)) {
+            vxhsDbg("vDisk %s, vDisk device failed "
+                      "iodir = %d size = %lu offset = %lu\n",
+                      s->vdisk_guid, iodir, size, offset);
+            s->vdisk_aio_count--;
+            vxhs_dec_acb_segment_count(acb, 1);
+            VXHS_SPIN_UNLOCK(s->vdisk_lock);
+            goto errout;
+        }
+        if (OF_VDISK_IOFAILOVER_IN_PROGRESS(s)) {
+            /*
+             * Queue all incoming io requests after failover starts.
+             * Number of requests that can arrive is limited by io queue depth
+             * so an app blasting independent ios will not exhaust memory.
+             */
+            QSIMPLEQ_INSERT_TAIL(&s->vdisk_aio_retryq, acb, retry_entry);
+            s->vdisk_aio_retry_qd++;
+            OF_AIOCB_FLAGS_SET_QUEUED(acb);
+            s->vdisk_aio_count--;
+            vxhs_dec_acb_segment_count(acb, 1);
+            VXHS_SPIN_UNLOCK(s->vdisk_lock);
+            vxhsDbg("vDisk %s, added acb %p to retry queue(2)\n",
+                      s->vdisk_guid, acb);
+            goto out;
+        }
+        OF_VDISK_SET_IOFAILOVER_IN_PROGRESS(s);
+        QSIMPLEQ_INSERT_TAIL(&s->vdisk_aio_retryq, acb, retry_entry);
+        s->vdisk_aio_retry_qd++;
+        OF_AIOCB_FLAGS_SET_QUEUED(acb);
+        vxhs_dec_acb_segment_count(acb, 1);
+        vxhsDbg("vDisk %s, added acb %p to retry queue(3)\n",
+                  s->vdisk_guid, acb);
+        /*
+         * Start I/O failover if there is no active
+         * AIO within vxhs block driver.
+         */
+        if (--s->vdisk_aio_count == 0) {
+            VXHS_SPIN_UNLOCK(s->vdisk_lock);
+            /*
+             * Start IO failover
+             */
+            vxhs_failover_io(s);
+            goto out;
+        }
+        VXHS_SPIN_UNLOCK(s->vdisk_lock);
+    }
+
+out:
+    return &acb->common;
+
+errout:
+    qemu_aio_unref(acb);
+    return NULL;
+}
+
+/*
+ * This is called from qemu-img utility when user want to resize
+ * the disk. Currently it's noop within VXHS block driver.
+ */
+int vxhs_truncate(BlockDriverState *bs, int64_t offset)
+{
+    BDRVVXHSState *s = bs->opaque;
+    int ret = 0;
+
+    vxhsErr("Truncating disk (%s): BlockDriverState = %p, "
+              "BDRVVXHSState = %p offset = %lu\n",
+              s->vdisk_guid, bs, s, offset);
+
+    return ret;
+}
+
+BlockAIOCB *vxhs_aio_readv(BlockDriverState *bs,
+                                   int64_t sector_num, QEMUIOVector *qiov,
+                                   int nb_sectors,
+                                   BlockCompletionFunc *cb, void *opaque)
+{
+    /*
+     * vxhsDbg("READING: opaque = %p size = %d offset = %lu\n",
+     *           opaque, nb_sectors * BDRV_SECTOR_SIZE, sector_num);
+     */
+    return vxhs_aio_rw(bs, sector_num, qiov, nb_sectors,
+                         cb, opaque, VDISK_AIO_READ);
+}
+
+BlockAIOCB *vxhs_aio_writev(BlockDriverState *bs,
+                                    int64_t sector_num, QEMUIOVector *qiov,
+                                    int nb_sectors,
+                                    BlockCompletionFunc *cb, void *opaque)
+{
+    /*
+     * vxhsDbg("WRITING: opaque = %p size = %d offset = %lu\n",
+     *           opaque, nb_sectors * BDRV_SECTOR_SIZE, sector_num);
+     */
+    return vxhs_aio_rw(bs, sector_num, qiov, nb_sectors,
+                         cb, opaque, VDISK_AIO_WRITE);
+}
+
+/*
+ * This is called by QEMU when flush inside guest triggered
+ * at block layer either for IDE or SCSI disks.
+ */
+int vxhs_co_flush(BlockDriverState *bs)
+{
+    BDRVVXHSState *s = bs->opaque;
+    uint64_t size = 0;
+    int ret = 0;
+    uint32_t iocount = 0;
+
+    ret = (*qnioops.qemu_iio_ioctl)(s->qnio_ctx,
+            s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
+            VDISK_AIO_FLUSH, &size, NULL, IIO_FLAG_SYNC);
+
+    if (ret < 0) {
+        /*
+         * Currently not handling the flush ioctl
+         * failure because of network connection
+         * disconnect. Since all the writes are
+         * commited into persistent storage hence
+         * this flush call is noop and we can safely
+         * return success status to the caller.
+         *
+         * If any write failure occurs for inflight
+         * write AIO because of network disconnect
+         * then anyway IO failover will be triggered.
+         */
+        vxhsDbg("vDisk (%s) Flush ioctl failed ret = %d errno = %d\n",
+                  s->vdisk_guid, ret, errno);
+        ret = 0;
+    }
+
+    iocount = vxhs_get_vdisk_iocount(s);
+    if (iocount > 0) {
+        vxhsDbg("In the flush the IO count = %d\n", iocount);
+    }
+
+    return ret;
+}
+
+/*
+ * This is called by guest or QEMU to free blocks.
+ * When block freed when files deleted in the guest, fstrim utility
+ * can be used to pass the hints to the block layer if the disk supports
+ * TRIM. It send WRITE_SAME SCSI command to QEMU virtio-scsi layer, which
+ * call bdrv_aio_discard interface.
+ */
+coroutine_fn int vxhs_co_pdiscard(BlockDriverState *bs,
+                                   int64_t sector_num, int nb_sectors)
+{
+    int64_t off, size;
+
+    off = sector_num * BDRV_SECTOR_SIZE;
+    size = nb_sectors * BDRV_SECTOR_SIZE;
+
+    vxhsErr("We are faking the discard for range off = %lu "
+              "for %lu bytes\n", off, size);
+    vxhsErr("returning from discard\n");
+
+    return 0;
+}
+
+unsigned long vxhs_get_vdisk_stat(BDRVVXHSState *s)
+{
+    void *ctx = NULL;
+    int flags = 0;
+    unsigned long vdisk_size = 0;
+    int ret = 0;
+
+    ret = (*qnioops.qemu_iio_ioctl)(s->qnio_ctx,
+            s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
+            VDISK_STAT, &vdisk_size, ctx, flags);
+
+    if (ret < 0) {
+        vxhsDbg("vDisk (%s) stat ioctl failed, ret = %d, errno = %d\n",
+                  s->vdisk_guid, ret, errno);
+    }
+    vxhsDbg("vDisk size = %lu\n", vdisk_size);
+
+    return vdisk_size;
+}
+
+/*
+ * Returns the size of vDisk in bytes. This is required
+ * by QEMU block upper block layer so that it is visible
+ * to guest.
+ */
+int64_t vxhs_getlength(BlockDriverState *bs)
+{
+    BDRVVXHSState *s = bs->opaque;
+    unsigned long vdisk_size = 0;
+
+    if (s->vdisk_size > 0) {
+        vdisk_size = s->vdisk_size;
+    } else {
+        /*
+         * Fetch the vDisk size using stat ioctl
+         */
+        vdisk_size = vxhs_get_vdisk_stat(s);
+        if (vdisk_size > 0) {
+            s->vdisk_size = vdisk_size;
+        }
+    }
+
+    if (vdisk_size > 0) {
+        return (int64_t)vdisk_size; /* return size in bytes */
+    } else {
+        return -EIO;
+    }
+}
+
+/*
+ * Returns actual blocks allocated for the vDisk.
+ * This is required by qemu-img utility.
+ */
+int64_t vxhs_get_allocated_blocks(BlockDriverState *bs)
+{
+    BDRVVXHSState *s = bs->opaque;
+    unsigned long vdisk_size = 0;
+
+    if (s->vdisk_size > 0) {
+        vdisk_size = s->vdisk_size;
+    } else {
+        /*
+         * TODO:
+         * Once HyperScale storage-virtualizer provides
+         * actual physical allocation of blocks then
+         * fetch that information and return back to the
+         * caller but for now just get the full size.
+         */
+        vdisk_size = vxhs_get_vdisk_stat(s);
+        if (vdisk_size > 0) {
+            s->vdisk_size = vdisk_size;
+            vxhsDbg("Allocated blocks = %lu\n", vdisk_size);
+        }
+    }
+
+    if (vdisk_size > 0) {
+        return (int64_t)vdisk_size; /* return size in bytes */
+    } else {
+        return -EIO;
+    }
+}
+
+void vxhs_close(BlockDriverState *bs)
+{
+    BDRVVXHSState *s = bs->opaque;
+
+    vxhsDbg("closing vDisk\n");
+
+    close(s->fds[VDISK_FD_READ]);
+    close(s->fds[VDISK_FD_WRITE]);
+
+    if (s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd >= 0) {
+        qnioops.qemu_iio_devclose(s->qnio_ctx,
+            s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd);
+    }
+    if (s->vdisk_lock) {
+        VXHS_SPIN_LOCK_DESTROY(s->vdisk_lock);
+        s->vdisk_lock = NULL;
+    }
+    if (s->vdisk_acb_lock) {
+        VXHS_SPIN_LOCK_DESTROY(s->vdisk_acb_lock);
+        s->vdisk_acb_lock = NULL;
+    }
+
+    /*
+     * never close channel - not ref counted, will
+     * close for all vdisks
+     */
+
+    vxhsDbg("vxhs_close: done\n");
+
+    /*
+     * TODO: Verify that all the resources were relinguished.
+     */
+}
+
+int vxhs_has_zero_init(BlockDriverState *bs)
+{
+    vxhsDbg("Returning without doing anything (noop).\n");
+
+    return 0;
+}
+
+/*
+ * If errors are consistent with storage agent failure:
+ *  - Try to reconnect in case error is transient or storage agent restarted.
+ *  - Currently failover is being triggered on per vDisk basis. There is
+ *    a scope of further optimization where failover can be global (per VM).
+ *  - In case of network (storage agent) failure, for all the vDisks, having
+ *    no redundency, I/Os will be failed without attempting for I/O failover
+ *    because of stateless nature of vDisk.
+ *  - If local or source storage agent is down then send an ioctl to remote
+ *    storage agent to check if remote storage agent in a state to accept
+ *    application I/Os.
+ *  - Once remote storage agent is ready to accept I/O, start I/O shipping.
+ *  - If I/Os cannot be serviced then vDisk will be marked failed so that
+ *    new incoming I/Os are returned with failure immediately.
+ *  - If vDisk I/O failover is in progress then all new/inflight I/Os will
+ *    queued and will be restarted or failed based on failover operation
+ *    is successful or not.
+ *  - I/O failover can be started either in I/O forward or I/O backward
+ *    path.
+ *  - I/O failover will be started as soon as all the pending acb(s)
+ *    are queued and there is no pending I/O count.
+ *  - If I/O failover couldn't be completed within QNIO_CONNECT_TIMOUT_SECS
+ *    then vDisk will be marked failed and all I/Os will be completed with
+ *    error.
+ */
+
+int vxhs_switch_storage_agent(BDRVVXHSState *s)
+{
+    int res = 0;
+    int flags = (IIO_FLAG_ASYNC | IIO_FLAG_DONE);
+
+    vxhsDbg("Query host %s for vdisk %s\n",
+              s->vdisk_hostinfo[s->vdisk_ask_failover_idx].hostip,
+              s->vdisk_guid);
+
+    res = vxhs_reopen_vdisk(s, s->vdisk_ask_failover_idx);
+    if (res == 0) {
+        res = (*qnioops.qemu_iio_ioctl)(s->qnio_ctx,
+                   s->vdisk_hostinfo[s->vdisk_ask_failover_idx].vdisk_rfd,
+                   VDISK_CHECK_IO_FAILOVER_READY, NULL, s, flags);
+    }
+    if (res != 0) {
+        vxhsDbg("Query to host %s for vdisk %s failed, res = %d, errno = %d\n",
+                  s->vdisk_hostinfo[s->vdisk_ask_failover_idx].hostip,
+                  s->vdisk_guid, res, errno);
+        /*
+         * TODO: calling failover_ioctl_cb from here ties up the qnio epoll
+         * loop if qemu_iio_ioctl fails synchronously (-1) for all hosts in io
+         * target list.
+         */
+
+        /* try next host */
+        failover_ioctl_cb(res, s);
+    }
+    return res;
+}
+
+void failover_ioctl_cb(int res, void *ctx)
+{
+    BDRVVXHSState *s = ctx;
+
+    if (res == 0) {
+        /* found failover target */
+        s->vdisk_cur_host_idx = s->vdisk_ask_failover_idx;
+        s->vdisk_ask_failover_idx = 0;
+        vxhsDbg("Switched to storage server host-IP %s for vdisk %s\n",
+                   s->vdisk_hostinfo[s->vdisk_cur_host_idx].hostip,
+                   s->vdisk_guid);
+        VXHS_SPIN_LOCK(s->vdisk_lock);
+        OF_VDISK_RESET_IOFAILOVER_IN_PROGRESS(s);
+        VXHS_SPIN_UNLOCK(s->vdisk_lock);
+        vxhs_handle_queued_ios(s);
+    } else {
+        /* keep looking */
+        vxhsDbg("failover_ioctl_cb: keep looking for io target for vdisk %s\n",
+                  s->vdisk_guid);
+        s->vdisk_ask_failover_idx++;
+        if (s->vdisk_ask_failover_idx == s->vdisk_nhosts) {
+            /* pause and cycle through list again */
+            sleep(QNIO_CONNECT_RETRY_SECS);
+            s->vdisk_ask_failover_idx = 0;
+        }
+        res = vxhs_switch_storage_agent(s);
+    }
+}
+
+int vxhs_failover_io(BDRVVXHSState *s)
+{
+    int res = 0;
+
+    vxhsDbg("I/O Failover starting for vDisk %s", s->vdisk_guid);
+
+    s->vdisk_ask_failover_idx = 0;
+    res = vxhs_switch_storage_agent(s);
+
+    return res;
+}
+
+/*
+ * Try to reopen the vDisk on one of the available hosts
+ * If vDisk reopen is successful on any of the host then
+ * check if that node is ready to accept I/O.
+ */
+int vxhs_reopen_vdisk(BDRVVXHSState *s, int index)
+{
+    char *of_vsa_addr = NULL;
+    char *file_name = NULL;
+    int  res = 0;
+
+    /*
+     * Don't close the channel if it was opened
+     * before successfully. It will be handled
+     * within iio* api if the same channel open
+     * fd is reused.
+     *
+     * close stale vdisk device remote fd since
+     * it is invalid after channel disconnect.
+     */
+    if (s->vdisk_hostinfo[index].vdisk_rfd >= 0) {
+        qnioops.qemu_iio_devclose(s->qnio_ctx,
+                                 s->vdisk_hostinfo[index].vdisk_rfd);
+        s->vdisk_hostinfo[index].vdisk_rfd = -1;
+    }
+    /*
+     * build storage agent address and vdisk device name strings
+     */
+    of_vsa_addr = (char *) malloc(sizeof(char) * OF_MAX_SERVER_ADDR);
+    if (!of_vsa_addr) {
+        res = ENOMEM;
+        goto out;
+    }
+    file_name = (char *) malloc(sizeof(char) * OF_MAX_FILE_LEN);
+    if (!file_name) {
+        res = ENOMEM;
+        goto out;
+    }
+    snprintf(file_name, OF_MAX_FILE_LEN, "%s%s", vdisk_prefix, s->vdisk_guid);
+    snprintf(of_vsa_addr, OF_MAX_SERVER_ADDR, "of://%s:%d",
+             s->vdisk_hostinfo[index].hostip, s->vdisk_hostinfo[index].port);
+    /*
+     * open iridum channel to storage agent if not opened before.
+     */
+    if (s->vdisk_hostinfo[index].qnio_cfd < 0) {
+        vxhsDbg("Trying to connect "
+                  "host-IP %s\n", s->vdisk_hostinfo[index].hostip);
+        s->vdisk_hostinfo[index].qnio_cfd =
+                (*qnioops.qemu_open_iio_conn)(global_qnio_ctx, of_vsa_addr, 0);
+        if (s->vdisk_hostinfo[index].qnio_cfd < 0) {
+            vxhsDbg("Failed to connect "
+                      "to storage agent on host-ip %s\n",
+                      s->vdisk_hostinfo[index].hostip);
+            res = ENODEV;
+            goto out;
+        }
+    }
+    /*
+     * open vdisk device
+     */
+    vxhsDbg("Trying to open vdisk device: %s\n", file_name);
+    s->vdisk_hostinfo[index].vdisk_rfd =
+            (*qnioops.qemu_iio_devopen)(global_qnio_ctx,
+             s->vdisk_hostinfo[index].qnio_cfd, file_name, 0);
+    if (s->vdisk_hostinfo[index].vdisk_rfd < 0) {
+        vxhsDbg("Failed to open vdisk device: %s\n", file_name);
+        res = EIO;
+        goto out;
+    }
+out:
+    if (of_vsa_addr) {
+        free(of_vsa_addr);
+    }
+    if (file_name) {
+        free(file_name);
+    }
+    return res;
+}
+
+/*
+ * vxhs_build_io_target_list: Initialize io target list with ip addresses of
+ * local storage agent and reflection target storage agents. The local storage
+ * agent ip is the efficient internal address in the uri, e.g. 192.168.0.2.
+ * The local storage agent address is stored at index 0. The reflection target
+ * ips, are the E-W data network addresses of the reflection node agents, also
+ * extracted from the uri.
+ *
+ */
+int vxhs_build_io_target_list(BDRVVXHSState *s, int resilency_count,
+                              char **filenames)
+{
+    URI *uri = NULL;
+    int i = 0;
+
+    /*
+     * TODO : We need to move to dynamic allocation of number of hosts.
+     * s->vdisk_hostinfo = (VXHSvDiskHostsInfo **) malloc (
+     *                      sizeof(VXHSvDiskHostsInfo) * resilency_count);
+     *  memset(&s->vdisk_hostinfo, 0, sizeof(VXHSvDiskHostsInfo) * MAX_HOSTS);
+     */
+    for (i = 0; i < resilency_count; i++) {
+        uri = uri_parse(filenames[i]);
+        s->vdisk_hostinfo[i].hostip = (char *)malloc(strlen(uri->server));
+        strncpy((s->vdisk_hostinfo[i].hostip), uri->server, IP_ADDR_LEN);
+        s->vdisk_hostinfo[i].port = uri->port;
+        s->vdisk_hostinfo[i].qnio_cfd = -1;
+        s->vdisk_hostinfo[i].vdisk_rfd = -1;
+        if (strstr(uri->path, "vxhs") == NULL) {
+            s->vdisk_guid = (char *)malloc(strlen(uri->path));
+            strcpy((s->vdisk_guid), uri->path);
+        }
+        uri_free(uri);
+    }
+    s->vdisk_nhosts = resilency_count;
+    s->vdisk_cur_host_idx = 0;
+
+   return 0;
+}
+
+int vxhs_handle_queued_ios(BDRVVXHSState *s)
+{
+    VXHSAIOCB *acb = NULL;
+    int res = 0;
+
+    VXHS_SPIN_LOCK(s->vdisk_lock);
+    while ((acb = QSIMPLEQ_FIRST(&s->vdisk_aio_retryq)) != NULL) {
+        /*
+         * Before we process the acb, check whether I/O failover
+         * started again due to failback or cascading failure.
+         */
+        if (OF_VDISK_IOFAILOVER_IN_PROGRESS(s)) {
+            VXHS_SPIN_UNLOCK(s->vdisk_lock);
+            goto out;
+        }
+        QSIMPLEQ_REMOVE_HEAD(&s->vdisk_aio_retryq, retry_entry);
+        s->vdisk_aio_retry_qd--;
+        OF_AIOCB_FLAGS_RESET_QUEUED(acb);
+        if (OF_VDISK_FAILED(s)) {
+            VXHS_SPIN_UNLOCK(s->vdisk_lock);
+            vxhs_fail_aio(acb, EIO);
+            VXHS_SPIN_LOCK(s->vdisk_lock);
+        } else {
+            VXHS_SPIN_UNLOCK(s->vdisk_lock);
+            res = vxhs_restart_aio(acb);
+            vxhsDbg("Restarted acb %p res %d\n", acb, res);
+            VXHS_SPIN_LOCK(s->vdisk_lock);
+            if (res) {
+                QSIMPLEQ_INSERT_TAIL(&s->vdisk_aio_retryq,
+                                     acb, retry_entry);
+                OF_AIOCB_FLAGS_SET_QUEUED(acb);
+                VXHS_SPIN_UNLOCK(s->vdisk_lock);
+                vxhsDbg("vDisk %s, added acb %p to retry queue(4)\n",
+                          s->vdisk_guid, acb);
+                goto out;
+            }
+        }
+    }
+    VXHS_SPIN_UNLOCK(s->vdisk_lock);
+out:
+    return res;
+}
+
+int vxhs_restart_aio(VXHSAIOCB *acb)
+{
+    BDRVVXHSState *s = NULL;
+    int iio_flags = 0;
+    int res = 0;
+
+    s = acb->common.bs->opaque;
+
+    if (acb->direction == VDISK_AIO_WRITE) {
+        vxhs_inc_vdisk_iocount(s, 1);
+        vxhs_inc_acb_segment_count(acb, 1);
+        iio_flags = (IIO_FLAG_DONE | IIO_FLAG_ASYNC);
+        res = (*qnioops.qemu_iio_writev)(s->qnio_ctx,
+                s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
+                acb->qiov->iov, acb->qiov->niov,
+                acb->io_offset, (void *)acb, iio_flags);
+    }
+
+    if (acb->direction == VDISK_AIO_READ) {
+        vxhs_inc_vdisk_iocount(s, 1);
+        vxhs_inc_acb_segment_count(acb, 1);
+        iio_flags = (IIO_FLAG_DONE | IIO_FLAG_ASYNC);
+        res = (*qnioops.qemu_iio_readv)(s->qnio_ctx,
+                s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
+                acb->qiov->iov, acb->qiov->niov,
+                acb->io_offset, (void *)acb, iio_flags);
+    }
+
+    if (res != 0) {
+        vxhs_dec_vdisk_iocount(s, 1);
+        vxhs_dec_acb_segment_count(acb, 1);
+        vxhsDbg("IO ERROR FOR: Read/Write = %d "
+                  "Error = %d, errno = %d\n",
+                  acb->direction, res, errno);
+    }
+
+    return res;
+}
+
+void vxhs_fail_aio(VXHSAIOCB *acb, int err)
+{
+    BDRVVXHSState *s = NULL;
+    int segcount = 0;
+    int rv = 0;
+
+    s = acb->common.bs->opaque;
+
+    vxhsDbg("vDisk %s, failing acb %p\n", s->vdisk_guid, acb);
+    if (!acb->ret) {
+        acb->ret = err;
+    }
+    VXHS_SPIN_LOCK(s->vdisk_acb_lock);
+    segcount = acb->segments;
+    VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
+    if (segcount == 0) {
+        /*
+         * Complete the io request
+         */
+        rv = qemu_write_full(s->fds[VDISK_FD_WRITE], &acb, sizeof(acb));
+        if (rv != sizeof(acb)) {
+            error_report("VXHS AIO completion failed: %s",
+                         strerror(errno));
+            abort();
+        }
+    }
+}
+
+static BlockDriver bdrv_vxhs = {
+    .format_name                  = "vxhs",
+    .protocol_name                = "vxhs",
+    .instance_size                = sizeof(BDRVVXHSState),
+    .bdrv_file_open               = vxhs_open,
+    .bdrv_create                  = vxhs_create,
+    .bdrv_close                   = vxhs_close,
+    .bdrv_getlength               = vxhs_getlength,
+    .bdrv_get_allocated_file_size = vxhs_get_allocated_blocks,
+    .bdrv_truncate                = vxhs_truncate,
+    .bdrv_aio_readv               = vxhs_aio_readv,
+    .bdrv_aio_writev              = vxhs_aio_writev,
+    .bdrv_co_flush_to_disk        = vxhs_co_flush,
+    .bdrv_co_pdiscard             = vxhs_co_pdiscard,
+    .bdrv_has_zero_init           = vxhs_has_zero_init,
+};
+
+void bdrv_vxhs_init(void)
+{
+    vxhsDbg("Registering VXHS %d AIO driver\n", vxhs_drv_version);
+
+    bdrv_register(&bdrv_vxhs);
+
+    /*
+     * Initialize pthread mutex for of_global_ctx_lock
+     */
+    pthread_mutex_init(&of_global_ctx_lock, NULL);
+}
+
+
+/*
+ * The line below is how our drivier is initialized.
+ * DO NOT TOUCH IT
+ */
+block_init(bdrv_vxhs_init);
diff --git a/block/vxhs.h b/block/vxhs.h
new file mode 100644
index 0000000..23114e0
--- /dev/null
+++ b/block/vxhs.h
@@ -0,0 +1,355 @@
+/*
+ * QEMU Block driver for Veritas HyperScale (VxHS)
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Please follow QEMU coding guidelines while modifying this file.
+ * The QEMU coding guidelines need to be followed because this driver has
+ * to be submitted to QEMU community in near futute and we want to prevent any
+ * reduce the amount of work at that time.
+ * QEMU coding guidelines can be found at :
+ * http://git.qemu-project.org/?p=qemu.git;a=blob_plain;f=CODING_STYLE;hb=HEAD
+ */
+
+#ifndef VXHSD_H
+#define VXHSD_H
+
+#include <gmodule.h>
+#include <inttypes.h>
+#include <pthread.h>
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "block/block_int.h"
+#include "qemu/uri.h"
+#include "qemu/queue.h"
+
+/*
+ * #define VXHS_DEBUG
+ */
+
+#define vxhsErr(fmt, ...) { \
+    time_t t = time(0); \
+    char buf[9] = {0}; \
+    strftime(buf, 9, "%H:%M:%S", localtime(&t)); \
+    fprintf(stderr, "[%s: %lu] %d: %s():\t", buf, pthread_self(), \
+                __LINE__, __func__); \
+    fprintf(stderr, fmt, ## __VA_ARGS__); \
+}
+
+#ifdef VXHS_DEBUG
+#define vxhsDbg vxhsErr
+#else
+#define vxhsDbg(...)        {/**/}
+#endif
+
+#define OF_GUID_STR_LEN             40
+#define OF_GUID_STR_SZ              (OF_GUID_STR_LEN + 1)
+#define QNIO_CONNECT_RETRY_SECS     5
+#define QNIO_CONNECT_TIMOUT_SECS    120
+
+/* constants from io_qnio.h */
+#define IIO_REASON_DONE     0x00000004
+#define IIO_REASON_EVENT    0x00000008
+#define IIO_REASON_HUP      0x00000010
+
+/*
+ * IO specific flags
+ */
+#define IIO_FLAG_ASYNC      0x00000001
+#define IIO_FLAG_DONE       0x00000010
+#define IIO_FLAG_SYNC       0
+
+/* constants from error.h */
+#define VXERROR_RETRY_ON_SOURCE     44
+#define VXERROR_HUP                 901
+#define VXERROR_CHANNEL_HUP         903
+
+/* constants from iomgr.h and opcode.h */
+#define IRP_READ_REQUEST                    0x1FFF
+#define IRP_WRITE_REQUEST                   0x2FFF
+#define IRP_VDISK_CHECK_IO_FAILOVER_READY   2020
+
+/* Lock specific macros */
+#define VXHS_SPIN_LOCK_ALLOC                  \
+    ((*qnioops.qemu_initialize_lock)())
+#define VXHS_SPIN_LOCK(lock)                  \
+    ((*qnioops.qemu_spin_lock)(lock))
+#define VXHS_SPIN_UNLOCK(lock)                \
+    ((*qnioops.qemu_spin_unlock)(lock))
+#define VXHS_SPIN_LOCK_DESTROY(lock)          \
+    ((*qnioops.qemu_destroy_lock)(lock))
+
+typedef enum {
+    VDISK_AIO_READ,
+    VDISK_AIO_WRITE,
+    VDISK_STAT,
+    VDISK_TRUNC,
+    VDISK_AIO_FLUSH,
+    VDISK_AIO_RECLAIM,
+    VDISK_GET_GEOMETRY,
+    VDISK_CHECK_IO_FAILOVER_READY,
+    VDISK_AIO_LAST_CMD
+} VDISKAIOCmd;
+
+typedef enum {
+    VXHS_IO_INPROGRESS,
+    VXHS_IO_COMPLETED,
+    VXHS_IO_ERROR
+} VXHSIOState;
+
+
+typedef void *qemu_aio_ctx_t;
+typedef void (*qnio_callback_t)(ssize_t retval, void *arg);
+
+#define VDISK_FD_READ 0
+#define VDISK_FD_WRITE 1
+
+#define QNIO_VDISK_NONE        0x00
+#define QNIO_VDISK_CREATE      0x01
+
+/* max IO size supported by QEMU NIO lib */
+#define QNIO_MAX_IO_SIZE       4194304
+
+#define IP_ADDR_LEN             20
+#define OF_MAX_FILE_LEN         1024
+#define OF_MAX_SERVER_ADDR      1024
+#define MAX_HOSTS               4
+
+/*
+ * Opcodes for making IOCTL on QEMU NIO library
+ */
+#define BASE_OPCODE_SHARED     1000
+#define BASE_OPCODE_DAL        2000
+#define IRP_VDISK_STAT                  (BASE_OPCODE_SHARED + 5)
+#define IRP_VDISK_GET_GEOMETRY          (BASE_OPCODE_DAL + 17)
+#define IRP_VDISK_READ_PARTITION        (BASE_OPCODE_DAL + 18)
+#define IRP_VDISK_FLUSH                 (BASE_OPCODE_DAL + 19)
+
+/*
+ * BDRVVXHSState specific flags
+ */
+#define OF_VDISK_FLAGS_STATE_ACTIVE             0x0000000000000001
+#define OF_VDISK_FLAGS_STATE_FAILED             0x0000000000000002
+#define OF_VDISK_FLAGS_IOFAILOVER_IN_PROGRESS   0x0000000000000004
+
+#define OF_VDISK_ACTIVE(s)                                              \
+        ((s)->vdisk_flags & OF_VDISK_FLAGS_STATE_ACTIVE)
+#define OF_VDISK_SET_ACTIVE(s)                                          \
+        ((s)->vdisk_flags |= OF_VDISK_FLAGS_STATE_ACTIVE)
+#define OF_VDISK_RESET_ACTIVE(s)                                        \
+        ((s)->vdisk_flags &= ~OF_VDISK_FLAGS_STATE_ACTIVE)
+
+#define OF_VDISK_FAILED(s)                                              \
+        ((s)->vdisk_flags & OF_VDISK_FLAGS_STATE_FAILED)
+#define OF_VDISK_SET_FAILED(s)                                          \
+        ((s)->vdisk_flags |= OF_VDISK_FLAGS_STATE_FAILED)
+#define OF_VDISK_RESET_FAILED(s)                                        \
+        ((s)->vdisk_flags &= ~OF_VDISK_FLAGS_STATE_FAILED)
+
+#define OF_VDISK_IOFAILOVER_IN_PROGRESS(s)                              \
+        ((s)->vdisk_flags & OF_VDISK_FLAGS_IOFAILOVER_IN_PROGRESS)
+#define OF_VDISK_SET_IOFAILOVER_IN_PROGRESS(s)                          \
+        ((s)->vdisk_flags |= OF_VDISK_FLAGS_IOFAILOVER_IN_PROGRESS)
+#define OF_VDISK_RESET_IOFAILOVER_IN_PROGRESS(s)                        \
+        ((s)->vdisk_flags &= ~OF_VDISK_FLAGS_IOFAILOVER_IN_PROGRESS)
+
+/*
+ * VXHSAIOCB specific flags
+ */
+#define OF_ACB_QUEUED       0x00000001
+
+#define OF_AIOCB_FLAGS_QUEUED(a)            \
+        ((a)->flags & OF_ACB_QUEUED)
+#define OF_AIOCB_FLAGS_SET_QUEUED(a)        \
+        ((a)->flags |= OF_ACB_QUEUED)
+#define OF_AIOCB_FLAGS_RESET_QUEUED(a)      \
+        ((a)->flags &= ~OF_ACB_QUEUED)
+
+char vdisk_prefix[] = "/dev/of/vdisk";
+
+typedef struct qemu2qnio_ctx {
+    uint32_t            qnio_flag;
+    uint64_t            qnio_size;
+    char                *qnio_channel;
+    char                *target;
+    qnio_callback_t     qnio_cb;
+} qemu2qnio_ctx_t;
+
+typedef qemu2qnio_ctx_t qnio2qemu_ctx_t;
+
+typedef struct LibQNIOSymbol {
+        const char *name;
+        gpointer *addr;
+} LibQNIOSymbol;
+
+typedef void (*iio_cb_t) (uint32_t rfd, uint32_t reason, void *ctx,
+                          void *reply);
+
+typedef struct QNIOOps {
+    void * (*qemu_iio_init)(iio_cb_t cb);
+    int32_t (* qemu_open_iio_conn)(void *qnio_ctx, const char *uri,
+                                       uint32_t flags);
+    int32_t (*qemu_iio_devopen)(void *qnio_ctx, uint32_t cfd,
+                                     const char *devpath, uint32_t flags);
+    int32_t (*qemu_iio_devclose)(void *qnio_ctx, uint32_t rfd);
+    int32_t (*qemu_iio_writev)(void *qnio_ctx, uint32_t rfd,
+                                    struct iovec *iov, int iovcnt,
+                                    uint64_t offset, void *ctx,
+                                    uint32_t flags);
+    int32_t (*qemu_iio_readv)(void *qnio_ctx, uint32_t rfd,
+                                   struct iovec *iov, int iovcnt,
+                                   uint64_t offset, void *ctx, uint32_t flags);
+    int32_t (*qemu_iio_read)(void *qnio_ctx, uint32_t rfd,
+                                  unsigned char *buf, uint64_t size,
+                                  uint64_t offset, void *ctx, uint32_t flags);
+    int32_t (*qemu_iio_ioctl)(void *apictx, uint32_t rfd, uint32_t opcode,
+                                   void *in, void *ctx, uint32_t flags);
+    int32_t (*qemu_iio_close)(void *qnio_ctx, uint32_t cfd);
+    uint32_t (*qemu_iio_extract_msg_error)(void *ptr);
+    size_t (*qemu_iio_extract_msg_size)(void *ptr);
+    uint32_t (*qemu_iio_extract_msg_opcode)(void *ptr);
+    void * (*qemu_initialize_lock)(void);
+    void (*qemu_spin_lock)(void *ptr);
+    void (*qemu_spin_unlock)(void *ptr);
+    void (*qemu_destroy_lock)(void *ptr);
+} QNIOOps;
+
+int32_t qemu_open_qnio_conn(const char *uri, uint32_t lanes,
+                               uint32_t flags);
+int32_t qemu_iio_devopen(void *qnio_ctx, uint32_t cfd,
+                         const char *devpath, uint32_t flags);
+int32_t qemu_iio_writev(void *qnio_ctx, uint32_t rfd, void *ctx,
+                        uint64_t offset, uint32_t count,
+                        struct iovec *iov, uint32_t flags);
+int32_t qemu_iio_readv(void *qnio_ctx, uint32_t rfd, void *ctx,
+                       uint64_t offset, uint32_t count,
+                       struct iovec *iov, uint32_t flags);
+
+/*
+ * HyperScale AIO callbacks structure
+ */
+typedef struct VXHSAIOCB {
+    BlockAIOCB    common;
+    size_t              ret;
+    size_t              size;
+    QEMUBH              *bh;
+    int                 aio_done;
+    int                 segments;
+    int                 flags;
+    size_t              io_offset;
+    QEMUIOVector        *qiov;
+    void                *buffer;
+    int                 direction;  /* IO direction (r/w) */
+    QSIMPLEQ_ENTRY(VXHSAIOCB) retry_entry;
+} VXHSAIOCB;
+
+typedef struct VXHSvDiskHostsInfo {
+    int     qnio_cfd;        /* Channel FD */
+    int     vdisk_rfd;      /* vDisk remote FD */
+    char    *hostip;        /* Host's IP addresses */
+    int     port;           /* Host's port number */
+} VXHSvDiskHostsInfo;
+
+/*
+ * Structure per vDisk maintained for state
+ */
+typedef struct BDRVVXHSState {
+    int                     fds[2];
+    int64_t                 vdisk_size;
+    int64_t                 vdisk_blocks;
+    int64_t                 vdisk_flags;
+    int                     vdisk_aio_count;
+    int                     event_reader_pos;
+    VXHSAIOCB             *qnio_event_acb;
+    void                    *qnio_ctx;
+    void                    *vdisk_lock; /* Lock to protect BDRVVXHSState */
+    void                    *vdisk_acb_lock;  /* Protects ACB */
+    VXHSvDiskHostsInfo    vdisk_hostinfo[MAX_HOSTS]; /* Per host info */
+    int                     vdisk_nhosts;   /* Total number of hosts */
+    int                     vdisk_cur_host_idx; /* IOs are being shipped to */
+    int                     vdisk_ask_failover_idx; /*asking permsn to ship io*/
+    QSIMPLEQ_HEAD(aio_retryq, VXHSAIOCB) vdisk_aio_retryq;
+    int                     vdisk_aio_retry_qd;
+    char                    *vdisk_guid;
+    AioContext              *aio_context;
+} BDRVVXHSState;
+
+int vxhs_load_iio_ops(void);
+void bdrv_vxhs_init(void);
+void *vxhs_initialize(void);
+void *vxhs_setup_qnio(void);
+int qemu_qnio_fini(BDRVVXHSState *s);
+void vxhs_iio_callback(uint32_t rfd, uint32_t reason, void *ctx, void *m);
+int qemu_qnio_init(BDRVVXHSState *s, const char *vxhs_uri);
+void vxhs_aio_event_reader(void *opaque);
+void vxhs_complete_aio(VXHSAIOCB *acb, BDRVVXHSState *s);
+int vxhs_aio_flush_cb(void *opaque);
+void vxhs_finish_aiocb(ssize_t ret, void *arg);
+unsigned long vxhs_get_vdisk_stat(BDRVVXHSState *s);
+int vxhs_open(BlockDriverState *bs, QDict *options,
+              int bdrv_flags, Error **errp);
+int vxhs_create(const char *filename, QemuOpts *options,
+                Error **errp);
+int vxhs_open_device(const char *vxhs_uri, int *cfd, int *rfd,
+                       BDRVVXHSState *s);
+void vxhs_close(BlockDriverState *bs);
+void vxhs_aio_cancel(BlockAIOCB *blockacb);
+int vxhs_truncate(BlockDriverState *bs, int64_t offset);
+int qemu_submit_io(BDRVVXHSState *s, struct iovec *iov, int64_t niov,
+                   int64_t offset, int cmd, qemu_aio_ctx_t acb);
+BlockAIOCB *vxhs_aio_flush(BlockDriverState *bs,
+                                   BlockCompletionFunc *cb, void *opaque);
+BlockAIOCB *vxhs_aio_pdiscard(BlockDriverState *bs, int64_t sector_num,
+                                     int nb_sectors,
+                                     BlockCompletionFunc *cb,
+                                     void *opaque);
+BlockAIOCB *vxhs_aio_readv(BlockDriverState *bs, int64_t sector_num,
+                                   QEMUIOVector *qiov, int nb_sectors,
+                                   BlockCompletionFunc *cb, void *opaque);
+BlockAIOCB *vxhs_aio_writev(BlockDriverState *bs, int64_t sector_num,
+                                    QEMUIOVector *qiov, int nb_sectors,
+                                    BlockCompletionFunc *cb,
+                                    void *opaque);
+coroutine_fn int vxhs_co_read(BlockDriverState *bs, int64_t sector_num,
+                                uint8_t *buf, int nb_sectors);
+coroutine_fn int vxhs_co_write(BlockDriverState *bs, int64_t sector_num,
+                                 const uint8_t *buf, int nb_sectors);
+int64_t vxhs_get_allocated_blocks(BlockDriverState *bs);
+BlockAIOCB *vxhs_aio_rw(BlockDriverState *bs, int64_t sector_num,
+                                QEMUIOVector *qiov, int nb_sectors,
+                                BlockCompletionFunc *cb,
+                                void *opaque, int write);
+int vxhs_co_flush(BlockDriverState *bs);
+coroutine_fn int vxhs_co_pdiscard(BlockDriverState *bs,
+                                   int64_t sector_num, int nb_sectors);
+int vxhs_has_zero_init(BlockDriverState *bs);
+int64_t vxhs_getlength(BlockDriverState *bs);
+inline void vxhs_inc_vdisk_iocount(void *ptr, uint32_t delta);
+inline void vxhs_dec_vdisk_iocount(void *ptr, uint32_t delta);
+inline uint32_t vxhs_get_vdisk_iocount(void *ptr);
+void vxhs_inc_acb_segment_count(void *ptr, int count);
+void vxhs_dec_acb_segment_count(void *ptr, int count);
+inline int vxhs_dec_and_get_acb_segment_count(void *ptr, int count);
+void vxhs_set_acb_buffer(void *ptr, void *buffer);
+int vxhs_sync_rw(BlockDriverState *bs, int64_t sector_num,
+                   const uint8_t *buf, int nb_sectors, int write);
+int vxhs_failover_io(BDRVVXHSState *s);
+int vxhs_reopen_vdisk(BDRVVXHSState *s,
+                        int hostinfo_index);
+int vxhs_switch_storage_agent(BDRVVXHSState *s);
+int vxhs_check_io_failover_ready(BDRVVXHSState *s,
+                                   int hostinfo_index);
+int vxhs_build_io_target_list(BDRVVXHSState *s, int resiliency_count,
+                              char **filenames);
+int vxhs_handle_queued_ios(BDRVVXHSState *s);
+int vxhs_restart_aio(VXHSAIOCB *acb);
+void vxhs_fail_aio(VXHSAIOCB *acb, int err);
+void failover_ioctl_cb(int res, void *ctx);
+char *vxhs_string_iterate(char *p, const char *d, const size_t len);
+int vxhs_tokenize(char **result, char *working, const char *src,
+                  const char *delim);
+
+#endif
diff --git a/configure b/configure
index f57fcc6..3456f26 100755
--- a/configure
+++ b/configure
@@ -320,6 +320,7 @@ vhdx=""
 numa=""
 tcmalloc="no"
 jemalloc="no"
+vxhs="yes"
 
 # parse CC options first
 for opt do
@@ -1150,6 +1151,11 @@ for opt do
   ;;
   --enable-jemalloc) jemalloc="yes"
   ;;
+  --disable-vxhs) vxhs="no"
+  ;;
+  --enable-vxhs) vxhs="yes"
+  ;;
+
   *)
       echo "ERROR: unknown option $opt"
       echo "Try '$0 --help' for more information"
@@ -1380,6 +1386,7 @@ disabled with --disable-FEATURE, default is enabled if available:
   numa            libnuma support
   tcmalloc        tcmalloc support
   jemalloc        jemalloc support
+  vxhs            Veritas HyperScale vDisk backend support
 
 NOTE: The object files are built at the place where configure is launched
 EOF
@@ -4541,7 +4548,18 @@ fi
 if do_cc -nostdlib -Wl,-r -Wl,--no-relax -o $TMPMO $TMPO; then
   LD_REL_FLAGS="-Wl,--no-relax"
 fi
-
+#################################################
+# gmodule support probe
+if $pkg_config --modversion glib-2.0 gmodule-2.0 > /dev/null 2>&1 ; then
+    glib_cflags=`$pkg_config --cflags glib-2.0 gmodule-2.0 2>/dev/null`
+    glib_libs=`$pkg_config --libs glib-2.0 gmodule-2.0 2>/dev/null`
+    LIBS="$glib_libs $LIBS"
+    LIBS="$glib_libs $LIBS"
+    libs_qga="$glib_libs $libs_qga"
+else
+    echo "glib-2.0 gmodule-2.0 required to compile QEMU"
+    exit 1
+fi
 ##########################################
 # End of CC checks
 # After here, no more $cc or $ld runs
@@ -5479,6 +5497,10 @@ if test "$pthread_setname_np" = "yes" ; then
   echo "CONFIG_PTHREAD_SETNAME_NP=y" >> $config_host_mak
 fi
 
+if test "$vxhs" = "yes" ; then
+  echo "CONFIG_VXHS=y" >> $config_host_mak
+fi
+
 if test "$tcg_interpreter" = "yes"; then
   QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/tci $QEMU_INCLUDES"
 elif test "$ARCH" = "sparc64" ; then
