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Re: [Qemu-devel] [PATCH v5 RFC] block/vxhs: Initial commit to add Verita


From: Paolo Bonzini
Subject: Re: [Qemu-devel] [PATCH v5 RFC] block/vxhs: Initial commit to add Veritas HyperScale VxHS block device support
Date: Thu, 8 Sep 2016 12:41:15 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0


On 07/09/2016 20:57, Ashish Mittal wrote:
> diff --git a/block/vxhs.c b/block/vxhs.c
> new file mode 100644
> index 0000000..813b7c2
> --- /dev/null
> +++ b/block/vxhs.c
> @@ -0,0 +1,1341 @@
> +/*
> + * QEMU Block driver for Veritas HyperScale (VxHS)
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "vxhs.h"
> +#include <qnio/qnio_api.h>
> +#include "trace.h"
> +#include "qapi/qmp/qerror.h"
> +#include "qapi/qmp/qdict.h"
> +#include "qapi/qmp/qstring.h"
> +
> +#define VXHS_OPT_FILENAME        "filename"
> +#define VXHS_OPT_VDISK_ID        "vdisk_id"
> +#define VXHS_OPT_SERVER          "server."
> +#define VXHS_OPT_HOST            "host"
> +#define VXHS_OPT_PORT            "port"
> +
> +/* qnio client ioapi_ctx */
> +static void *global_qnio_ctx;
> +
> +/* vdisk prefix to pass to qnio */
> +static const char vdisk_prefix[] = "/dev/of/vdisk";
> +
> +void vxhs_inc_acb_segment_count(void *ptr, int count)
> +{
> +    VXHSAIOCB *acb = ptr;
> +    BDRVVXHSState *s = acb->common.bs->opaque;
> +
> +    VXHS_SPIN_LOCK(s->vdisk_acb_lock);

Please use QemuSpin instead.

Paolo

> +    acb->segments += count;
> +    VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
> +}
> +
> +void vxhs_dec_acb_segment_count(void *ptr, int count)
> +{
> +    VXHSAIOCB *acb = ptr;
> +    BDRVVXHSState *s = acb->common.bs->opaque;
> +
> +    VXHS_SPIN_LOCK(s->vdisk_acb_lock);
> +    acb->segments -= count;
> +    VXHS_SPIN_UNLOCK(s->vdisk_acb_lock);
> +}
> +
> +int vxhs_dec_and_get_acb_segment_count(void *ptr, int count)
> +{
> +    VXHSAIOCB *acb = 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;
> +}
> +
> +void vxhs_set_acb_buffer(void *ptr, void *buffer)
> +{
> +    VXHSAIOCB *acb = ptr;
> +
> +    acb->buffer = buffer;
> +}
> +
> +void vxhs_inc_vdisk_iocount(void *ptr, uint32_t count)
> +{
> +    BDRVVXHSState *s = ptr;
> +
> +    VXHS_SPIN_LOCK(s->vdisk_lock);
> +    s->vdisk_aio_count += count;
> +    VXHS_SPIN_UNLOCK(s->vdisk_lock);
> +}
> +
> +void vxhs_dec_vdisk_iocount(void *ptr, uint32_t count)
> +{
> +    BDRVVXHSState *s = ptr;
> +
> +    VXHS_SPIN_LOCK(s->vdisk_lock);
> +    s->vdisk_aio_count -= count;
> +    VXHS_SPIN_UNLOCK(s->vdisk_lock);
> +}
> +
> +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 = qnio_iio_extract_msg_error(m);
> +        opcode = qnio_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 = ctx;
> +        s = acb->common.bs->opaque;
> +    } else {
> +        trace_vxhs_iio_callback(error, reason);
> +        goto out;
> +    }
> +
> +    if (error) {
> +        trace_vxhs_iio_callback_iofail(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 redundancy 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++;
> +                    trace_vxhs_iio_callback_retry(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
> +             */
> +            trace_vxhs_iio_callback_chnlfail(error);
> +            /*
> +             * TODO: Start channel failover when no I/O is outstanding
> +             */
> +            goto out;
> +        } else {
> +            trace_vxhs_iio_callback_fail(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;
> +    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);
> +        trace_vxhs_iio_callback_ready(((BDRVVXHSState *)ctx)->vdisk_guid,
> +                                      error);
> +        vxhs_failover_ioctl_cb(error, ctx);
> +        break;
> +
> +    default:
> +        if (reason == IIO_REASON_HUP) {
> +            /*
> +             * Channel failed, spontaneous notification,
> +             * not in response to I/O
> +             */
> +            trace_vxhs_iio_callback_chnfail(error, errno);
> +            /*
> +             * TODO: Start channel failover when no I/O is outstanding
> +             */
> +        } else {
> +            trace_vxhs_iio_callback_unknwn(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) {
> +        trace_vxhs_complete_aio(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 is invoked when any IO gets completed and written on pipe
> + * by callback called from QNIO thread context. Then it marks
> + * the AIO as completed, and releases 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);
> +}
> +
> +/*
> + * Call QNIO operation to create channels to do IO on vDisk.
> + */
> +
> +void *vxhs_setup_qnio(void)
> +{
> +    void *qnio_ctx = NULL;
> +
> +    qnio_ctx = qnio_iio_init(vxhs_iio_callback);
> +
> +    if (qnio_ctx != NULL) {
> +        trace_vxhs_setup_qnio(qnio_ctx);
> +    } else {
> +        trace_vxhs_setup_qnio_nwerror('.');
> +    }
> +
> +    return qnio_ctx;
> +}
> +
> +static QemuOptsList runtime_opts = {
> +    .name = "vxhs",
> +    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
> +    .desc = {
> +        {
> +            .name = VXHS_OPT_FILENAME,
> +            .type = QEMU_OPT_STRING,
> +            .help = "URI to the Veritas HyperScale image",
> +        },
> +        {
> +            .name = VXHS_OPT_VDISK_ID,
> +            .type = QEMU_OPT_STRING,
> +            .help = "UUID of the VxHS vdisk",
> +        },
> +        { /* end of list */ }
> +    },
> +};
> +
> +static QemuOptsList runtime_tcp_opts = {
> +    .name = "vxhs_tcp",
> +    .head = QTAILQ_HEAD_INITIALIZER(runtime_tcp_opts.head),
> +    .desc = {
> +        {
> +            .name = VXHS_OPT_HOST,
> +            .type = QEMU_OPT_STRING,
> +            .help = "host address (ipv4 addresses)",
> +        },
> +        {
> +            .name = VXHS_OPT_PORT,
> +            .type = QEMU_OPT_NUMBER,
> +            .help = "port number on which VxHSD is listening (default 9999)",
> +            .def_value_str = "9999"
> +        },
> +        {
> +            .name = "to",
> +            .type = QEMU_OPT_NUMBER,
> +            .help = "max port number, not supported by VxHS",
> +        },
> +        {
> +            .name = "ipv4",
> +            .type = QEMU_OPT_BOOL,
> +            .help = "ipv4 bool value, not supported by VxHS",
> +        },
> +        {
> +            .name = "ipv6",
> +            .type = QEMU_OPT_BOOL,
> +            .help = "ipv6 bool value, not supported by VxHS",
> +        },
> +        { /* end of list */ }
> +    },
> +};
> +
> +/*
> + * Parse the incoming URI and populate *options with all the host(s)
> + * information. Host at index 0 is local storage agent.
> + * Remaining are the 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.
> + */
> +static int vxhs_parse_uri(const char *filename, QDict *options)
> +{
> +    gchar **target_list;
> +    URI *uri = NULL;
> +    char *hoststr, *portstr;
> +    char *vdisk_id = NULL;
> +    char *port;
> +    int ret = 0;
> +    int i = 0;
> +
> +    trace_vxhs_parse_uri_filename(filename);
> +    target_list = g_strsplit(filename, "%7D", 0);
> +    assert(target_list != NULL && target_list[0] != NULL);
> +
> +    for (i = 0; target_list[i] != NULL && *target_list[i]; i++) {
> +        uri = uri_parse(target_list[i]);
> +        if (!uri || !uri->server) {
> +            uri_free(uri);
> +            ret = -EINVAL;
> +            break;
> +        }
> +
> +        hoststr = g_strdup_printf(VXHS_OPT_SERVER"%d.host", i);
> +        qdict_put(options, hoststr, qstring_from_str(uri->server));
> +
> +        portstr = g_strdup_printf(VXHS_OPT_SERVER"%d.port", i);
> +        if (uri->port) {
> +            port = g_strdup_printf("%d", uri->port);
> +            qdict_put(options, portstr, qstring_from_str(port));
> +            g_free(port);
> +        }
> +
> +        if (i == 0 && (strstr(uri->path, "vxhs") == NULL)) {
> +            vdisk_id = g_strdup_printf("%s%c", uri->path, '}');
> +            qdict_put(options, "vdisk_id", qstring_from_str(vdisk_id));
> +        }
> +
> +        trace_vxhs_parse_uri_hostinfo(i + 1, uri->server, uri->port);
> +        g_free(hoststr);
> +        g_free(portstr);
> +        g_free(vdisk_id);
> +        uri_free(uri);
> +    }
> +
> +    g_strfreev(target_list);
> +    return ret;
> +}
> +
> +static void vxhs_parse_filename(const char *filename, QDict *options,
> +                               Error **errp)
> +{
> +    if (qdict_haskey(options, "host")
> +        || qdict_haskey(options, "port")
> +        || qdict_haskey(options, "path"))
> +    {
> +        error_setg(errp, "host/port/path and a file name may not be 
> specified "
> +                         "at the same time");
> +        return;
> +    }
> +
> +    if (strstr(filename, "://")) {
> +        int ret = vxhs_parse_uri(filename, options);
> +        if (ret < 0) {
> +            error_setg(errp, "Invalid URI. URI should be of the form "
> +                       "  vxhs://<host_ip>:<port>/{<vdisk_id>}");
> +        }
> +    }
> +}
> +
> +static int vxhs_qemu_init(QDict *options, BDRVVXHSState *s,
> +                              int *cfd, int *rfd, Error **errp)
> +{
> +    QDict *backing_options = NULL;
> +    QemuOpts *opts, *tcp_opts;
> +    const char *vxhs_filename;
> +    char *of_vsa_addr = NULL;
> +    Error *local_err = NULL;
> +    const char *vdisk_id_opt;
> +    char *file_name = NULL;
> +    size_t num_servers = 0;
> +    char *str = NULL;
> +    int ret = 0;
> +    int i;
> +
> +    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
> +    qemu_opts_absorb_qdict(opts, options, &local_err);
> +    if (local_err) {
> +        ret = -EINVAL;
> +        goto out;
> +    }
> +
> +    vxhs_filename = qemu_opt_get(opts, VXHS_OPT_FILENAME);
> +    if (vxhs_filename) {
> +        trace_vxhs_qemu_init_filename(vxhs_filename);
> +    }
> +
> +    vdisk_id_opt = qemu_opt_get(opts, VXHS_OPT_VDISK_ID);
> +    if (!vdisk_id_opt) {
> +        error_setg(&local_err, QERR_MISSING_PARAMETER, VXHS_OPT_VDISK_ID);
> +        ret = -EINVAL;
> +        goto out;
> +    }
> +    s->vdisk_guid = g_strdup(vdisk_id_opt);
> +    trace_vxhs_qemu_init_vdisk(vdisk_id_opt);
> +
> +    num_servers = qdict_array_entries(options, VXHS_OPT_SERVER);
> +    if (num_servers < 1) {
> +        error_setg(&local_err, QERR_MISSING_PARAMETER, "server");
> +        ret = -EINVAL;
> +        goto out;
> +    } else if (num_servers > 4) {
> +        error_setg(&local_err, QERR_INVALID_PARAMETER, "server");
> +        error_append_hint(errp, "Maximum 4 servers allowed.\n");
> +        ret = -EINVAL;
> +        goto out;
> +    }
> +    trace_vxhs_qemu_init_numservers(num_servers);
> +
> +    for (i = 0; i < num_servers; i++) {
> +        str = g_strdup_printf(VXHS_OPT_SERVER"%d.", i);
> +        qdict_extract_subqdict(options, &backing_options, str);
> +
> +        /* Create opts info from runtime_tcp_opts list */
> +        tcp_opts = qemu_opts_create(&runtime_tcp_opts, NULL, 0, 
> &error_abort);
> +        qemu_opts_absorb_qdict(tcp_opts, backing_options, &local_err);
> +        if (local_err) {
> +            qdict_del(backing_options, str);
> +            qemu_opts_del(tcp_opts);
> +            g_free(str);
> +            ret = -EINVAL;
> +            goto out;
> +        }
> +
> +        s->vdisk_hostinfo[i].hostip = g_strdup(qemu_opt_get(tcp_opts,
> +                                                            VXHS_OPT_HOST));
> +        s->vdisk_hostinfo[i].port = g_ascii_strtoll(qemu_opt_get(tcp_opts,
> +                                                                 
> VXHS_OPT_PORT),
> +                                                    NULL, 0);
> +
> +        s->vdisk_hostinfo[i].qnio_cfd = -1;
> +        s->vdisk_hostinfo[i].vdisk_rfd = -1;
> +        trace_vxhs_qemu_init(s->vdisk_hostinfo[i].hostip,
> +                             s->vdisk_hostinfo[i].port);
> +
> +        qdict_del(backing_options, str);
> +        qemu_opts_del(tcp_opts);
> +        g_free(str);
> +    }
> +
> +    s->vdisk_nhosts = i;
> +    s->vdisk_cur_host_idx = 0;
> +    file_name = g_strdup_printf("%s%s", vdisk_prefix, s->vdisk_guid);
> +    of_vsa_addr = g_strdup_printf("of://%s:%d",
> +                                
> s->vdisk_hostinfo[s->vdisk_cur_host_idx].hostip,
> +                                
> s->vdisk_hostinfo[s->vdisk_cur_host_idx].port);
> +
> +    /*
> +     * .bdrv_open() and .bdrv_create() run under the QEMU global mutex.
> +     */
> +    if (global_qnio_ctx == NULL) {
> +        global_qnio_ctx = vxhs_setup_qnio();
> +        if (global_qnio_ctx == NULL) {
> +            error_setg(&local_err, "Failed vxhs_setup_qnio");
> +            ret = -EINVAL;
> +            goto out;
> +        }
> +    }
> +
> +    *cfd = qnio_open_iio_conn(global_qnio_ctx, of_vsa_addr, 0);
> +    if (*cfd < 0) {
> +        error_setg(&local_err, "Failed qnio_open_iio_conn");
> +        ret = -EIO;
> +        goto out;
> +    }
> +    *rfd = qnio_iio_devopen(global_qnio_ctx, *cfd, file_name, 0);
> +    if (*rfd < 0) {
> +        qnio_iio_close(global_qnio_ctx, *cfd);
> +        *cfd = -1;
> +        error_setg(&local_err, "Failed qnio_iio_devopen");
> +        ret = -EIO;
> +        goto out;
> +    }
> +
> +out:
> +    g_free(file_name);
> +    g_free(of_vsa_addr);
> +    qemu_opts_del(opts);
> +
> +    if (ret < 0) {
> +        for (i = 0; i < num_servers; i++) {
> +            g_free(s->vdisk_hostinfo[i].hostip);
> +        }
> +        g_free(s->vdisk_guid);
> +        s->vdisk_guid = NULL;
> +        errno = -ret;
> +    }
> +    error_propagate(errp, local_err);
> +    return ret;
> +}
> +
> +int vxhs_open(BlockDriverState *bs, QDict *options,
> +              int bdrv_flags, Error **errp)
> +{
> +    BDRVVXHSState *s = bs->opaque;
> +    AioContext *aio_context;
> +    int qemu_qnio_cfd = -1;
> +    int device_opened = 0;
> +    int qemu_rfd = -1;
> +    int ret = 0;
> +    int i;
> +
> +    ret = vxhs_qemu_init(options, s, &qemu_qnio_cfd, &qemu_rfd, errp);
> +    if (ret < 0) {
> +        trace_vxhs_open_fail(ret);
> +        return ret;
> +    } else {
> +        device_opened = 1;
> +    }
> +
> +    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);
> +
> +    /*
> +     * Create a pipe for communicating between two threads in different
> +     * context. Set handler for read event, which gets triggered when
> +     * IO completion is done by non-QEMU context.
> +     */
> +    ret = qemu_pipe(s->fds);
> +    if (ret < 0) {
> +        trace_vxhs_open_epipe('.');
> +        ret = -errno;
> +        goto errout;
> +    }
> +    fcntl(s->fds[VDISK_FD_READ], F_SETFL, O_NONBLOCK);
> +
> +    aio_context = bdrv_get_aio_context(bs);
> +    aio_set_fd_handler(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 being,
> +     *      we don't want the overhead of spin
> +     *      lock being dynamically allocated and
> +     *      freed for every AIO.
> +     */
> +    s->vdisk_lock = VXHS_SPIN_LOCK_ALLOC;
> +    s->vdisk_acb_lock = VXHS_SPIN_LOCK_ALLOC;
> +
> +    return 0;
> +
> +errout:
> +    /*
> +     * Close remote vDisk device if it was opened before
> +     */
> +    if (device_opened) {
> +        for (i = 0; i < s->vdisk_nhosts; i++) {
> +            if (s->vdisk_hostinfo[i].vdisk_rfd >= 0) {
> +                qnio_iio_devclose(s->qnio_ctx, 0,
> +                                         s->vdisk_hostinfo[i].vdisk_rfd);
> +                s->vdisk_hostinfo[i].vdisk_rfd = -1;
> +            }
> +            /*
> +             * close QNIO channel against cached channel open-fd
> +             */
> +            if (s->vdisk_hostinfo[i].qnio_cfd >= 0) {
> +                qnio_iio_close(s->qnio_ctx,
> +                                      s->vdisk_hostinfo[i].qnio_cfd);
> +                s->vdisk_hostinfo[i].qnio_cfd = -1;
> +            }
> +        }
> +    }
> +    trace_vxhs_open_fail(ret);
> +    return ret;
> +}
> +
> +static const AIOCBInfo vxhs_aiocb_info = {
> +    .aiocb_size = sizeof(VXHSAIOCB)
> +};
> +
> +/*
> + * This allocates QEMU-VXHS callback for each IO
> + * and is passed to QNIO. When QNIO completes 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)) {
> +        trace_vxhs_aio_rw(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);
> +        trace_vxhs_aio_rw_retry(s->vdisk_guid, acb, 1);
> +        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);
> +            ret = qnio_iio_writev(s->qnio_ctx,
> +                    s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
> +                    qiov->iov, qiov->niov, offset, (void *)acb, iio_flags);
> +            break;
> +    case VDISK_AIO_READ:
> +            vxhs_inc_acb_segment_count(acb, 1);
> +            ret = qnio_iio_readv(s->qnio_ctx,
> +                    s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
> +                    qiov->iov, qiov->niov, offset, (void *)acb, iio_flags);
> +            break;
> +    default:
> +            trace_vxhs_aio_rw_invalid(iodir);
> +            goto errout;
> +    }
> +
> +    if (ret != 0) {
> +        trace_vxhs_aio_rw_ioerr(
> +                  s->vdisk_guid, iodir, size, offset,
> +                  acb, acb->segments, ret, errno);
> +        /*
> +         * Don't retry I/Os against vDisk having no
> +         * redundancy or stateful storage on compute
> +         *
> +         * TODO: Revisit this code path to see if any
> +         *       particular error needs to be handled.
> +         *       At this moment failing the I/O.
> +         */
> +        VXHS_SPIN_LOCK(s->vdisk_lock);
> +        if (s->vdisk_nhosts == 1) {
> +            trace_vxhs_aio_rw_iofail(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)) {
> +            trace_vxhs_aio_rw_devfail(
> +                      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);
> +            trace_vxhs_aio_rw_retry(s->vdisk_guid, acb, 2);
> +            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);
> +        trace_vxhs_aio_rw_retry(s->vdisk_guid, acb, 3);
> +        /*
> +         * 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;
> +}
> +
> +BlockAIOCB *vxhs_aio_readv(BlockDriverState *bs,
> +                                   int64_t sector_num, QEMUIOVector *qiov,
> +                                   int nb_sectors,
> +                                   BlockCompletionFunc *cb, void *opaque)
> +{
> +    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)
> +{
> +    return vxhs_aio_rw(bs, sector_num, qiov, nb_sectors,
> +                         cb, opaque, VDISK_AIO_WRITE);
> +}
> +
> +/*
> + * This is called by QEMU when a flush gets triggered from within
> + * a guest at the 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;
> +
> +    /*
> +     * VDISK_AIO_FLUSH ioctl is a no-op at present.
> +     */
> +    ret = qnio_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.
> +         */
> +        trace_vxhs_co_flush(s->vdisk_guid, ret, errno);
> +        ret = 0;
> +    }
> +
> +    return ret;
> +}
> +
> +unsigned long vxhs_get_vdisk_stat(BDRVVXHSState *s)
> +{
> +    void *ctx = NULL;
> +    int flags = 0;
> +    int64_t vdisk_size = 0;
> +    int ret = 0;
> +
> +    ret = qnio_iio_ioctl(s->qnio_ctx,
> +            s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd,
> +            VDISK_STAT, &vdisk_size, ctx, flags);
> +
> +    if (ret < 0) {
> +        trace_vxhs_get_vdisk_stat_err(s->vdisk_guid, ret, errno);
> +        return 0;
> +    }
> +
> +    trace_vxhs_get_vdisk_stat(s->vdisk_guid, 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;
> +    int64_t 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 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;
> +    int64_t 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;
> +        }
> +    }
> +
> +    if (vdisk_size > 0) {
> +        return vdisk_size; /* return size in bytes */
> +    } else {
> +        return -EIO;
> +    }
> +}
> +
> +void vxhs_close(BlockDriverState *bs)
> +{
> +    BDRVVXHSState *s = bs->opaque;
> +    int i;
> +
> +    trace_vxhs_close(s->vdisk_guid);
> +    close(s->fds[VDISK_FD_READ]);
> +    close(s->fds[VDISK_FD_WRITE]);
> +
> +    /*
> +     * Clearing all the event handlers for oflame registered to QEMU
> +     */
> +    aio_set_fd_handler(bdrv_get_aio_context(bs), s->fds[VDISK_FD_READ],
> +                       false, NULL, NULL, NULL);
> +
> +    if (s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd >= 0) {
> +        qnio_iio_devclose(s->qnio_ctx, 0,
> +            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;
> +    }
> +
> +    g_free(s->vdisk_guid);
> +    s->vdisk_guid = NULL;
> +
> +    for (i = 0; i < VXHS_MAX_HOSTS; i++) {
> +        /*
> +         * Close vDisk device
> +         */
> +        if (s->vdisk_hostinfo[i].vdisk_rfd >= 0) {
> +            qnio_iio_devclose(s->qnio_ctx, 0,
> +                                     s->vdisk_hostinfo[i].vdisk_rfd);
> +            s->vdisk_hostinfo[i].vdisk_rfd = -1;
> +        }
> +
> +        /*
> +         * Close Iridium channel against cached channel-fd
> +         */
> +        if (s->vdisk_hostinfo[i].qnio_cfd >= 0) {
> +            qnio_iio_close(s->qnio_ctx,
> +                                  s->vdisk_hostinfo[i].qnio_cfd);
> +            s->vdisk_hostinfo[i].qnio_cfd = -1;
> +        }
> +
> +        /*
> +         * Free hostip string which is allocated dynamically
> +         */
> +        g_free(s->vdisk_hostinfo[i].hostip);
> +        s->vdisk_hostinfo[i].hostip = NULL;
> +        s->vdisk_hostinfo[i].port = 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 redundancy, 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);
> +
> +    trace_vxhs_switch_storage_agent(
> +              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 = qnio_iio_ioctl(s->qnio_ctx,
> +                  s->vdisk_hostinfo[s->vdisk_ask_failover_idx].vdisk_rfd,
> +                  VDISK_CHECK_IO_FAILOVER_READY, NULL, s, flags);
> +    } else {
> +        trace_vxhs_switch_storage_agent_failed(
> +                  s->vdisk_hostinfo[s->vdisk_ask_failover_idx].hostip,
> +                  s->vdisk_guid, res, errno);
> +        /*
> +         * TODO: calling vxhs_failover_ioctl_cb from here ties up the qnio 
> epoll
> +         * loop if qnio_iio_ioctl fails synchronously (-1) for all hosts in 
> io
> +         * target list.
> +         */
> +
> +        /* try next host */
> +        vxhs_failover_ioctl_cb(res, s);
> +    }
> +    return res;
> +}
> +
> +void vxhs_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;
> +        trace_vxhs_failover_ioctl_cb(
> +                   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 */
> +        trace_vxhs_failover_ioctl_cb_retry(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;
> +
> +    trace_vxhs_failover_io(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;
> +
> +
> +    /*
> +     * Close stale vdisk device remote fd since
> +     * it could be invalid fd after channel disconnect.
> +     * Reopen the vdisk to get the new fd.
> +     */
> +    if (s->vdisk_hostinfo[index].vdisk_rfd >= 0) {
> +        qnio_iio_devclose(s->qnio_ctx, 0,
> +                                 s->vdisk_hostinfo[index].vdisk_rfd);
> +        s->vdisk_hostinfo[index].vdisk_rfd = -1;
> +    }
> +
> +    /*
> +     * As part of vDisk reopen, close the QNIO channel
> +     * against cached channel-fd (fd is being cached into
> +     * vDisk hostinfo).
> +     */
> +    if (s->vdisk_hostinfo[index].qnio_cfd >= 0) {
> +        qnio_iio_close(s->qnio_ctx,
> +                              s->vdisk_hostinfo[index].qnio_cfd);
> +        s->vdisk_hostinfo[index].qnio_cfd = -1;
> +    }
> +
> +    /*
> +     * Build storage agent address and vdisk device name strings
> +     */
> +    file_name = g_strdup_printf("%s%s", vdisk_prefix, s->vdisk_guid);
> +    of_vsa_addr = g_strdup_printf("of://%s:%d",
> +             s->vdisk_hostinfo[index].hostip, s->vdisk_hostinfo[index].port);
> +    /*
> +     * Open qnio channel to storage agent if not opened before.
> +     */
> +    if (s->vdisk_hostinfo[index].qnio_cfd < 0) {
> +        s->vdisk_hostinfo[index].qnio_cfd =
> +                qnio_open_iio_conn(global_qnio_ctx, of_vsa_addr, 0);
> +        if (s->vdisk_hostinfo[index].qnio_cfd < 0) {
> +            trace_vxhs_reopen_vdisk(s->vdisk_hostinfo[index].hostip);
> +            res = ENODEV;
> +            goto out;
> +        }
> +    }
> +
> +    /*
> +     * Open vdisk device
> +     */
> +    s->vdisk_hostinfo[index].vdisk_rfd =
> +            qnio_iio_devopen(global_qnio_ctx,
> +             s->vdisk_hostinfo[index].qnio_cfd, file_name, 0);
> +
> +    if (s->vdisk_hostinfo[index].vdisk_rfd < 0) {
> +        /*
> +         * Close QNIO channel against cached channel-fd
> +         */
> +        if (s->vdisk_hostinfo[index].qnio_cfd >= 0) {
> +            qnio_iio_close(s->qnio_ctx,
> +                                  s->vdisk_hostinfo[index].qnio_cfd);
> +            s->vdisk_hostinfo[index].qnio_cfd = -1;
> +        }
> +
> +        trace_vxhs_reopen_vdisk_openfail(file_name);
> +        res = EIO;
> +        goto out;
> +    }
> +
> +out:
> +    g_free(of_vsa_addr);
> +    g_free(file_name);
> +    return res;
> +}
> +
> +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);
> +            trace_vxhs_handle_queued_ios(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);
> +                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 = qnio_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 = qnio_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);
> +        trace_vxhs_restart_aio(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;
> +
> +    trace_vxhs_fail_aio(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 void vxhs_detach_aio_context(BlockDriverState *bs)
> +{
> +    BDRVVXHSState *s = bs->opaque;
> +
> +    aio_set_fd_handler(bdrv_get_aio_context(bs), s->fds[VDISK_FD_READ],
> +                       false, NULL, NULL, NULL);
> +
> +}
> +
> +static void vxhs_attach_aio_context(BlockDriverState *bs,
> +                                   AioContext *new_context)
> +{
> +    BDRVVXHSState *s = bs->opaque;
> +
> +    aio_set_fd_handler(new_context, s->fds[VDISK_FD_READ],
> +                       false, vxhs_aio_event_reader, NULL, s);
> +}
> +
> +static BlockDriver bdrv_vxhs = {
> +    .format_name                  = "vxhs",
> +    .protocol_name                = "vxhs",
> +    .instance_size                = sizeof(BDRVVXHSState),
> +    .bdrv_file_open               = vxhs_open,
> +    .bdrv_parse_filename          = vxhs_parse_filename,
> +    .bdrv_close                   = vxhs_close,
> +    .bdrv_getlength               = vxhs_getlength,
> +    .bdrv_get_allocated_file_size = vxhs_get_allocated_blocks,
> +    .bdrv_aio_readv               = vxhs_aio_readv,
> +    .bdrv_aio_writev              = vxhs_aio_writev,
> +    .bdrv_co_flush_to_disk        = vxhs_co_flush,
> +    .bdrv_detach_aio_context      = vxhs_detach_aio_context,
> +    .bdrv_attach_aio_context      = vxhs_attach_aio_context,
> +};
> +
> +void bdrv_vxhs_init(void)
> +{
> +    trace_vxhs_bdrv_init('.');
> +    bdrv_register(&bdrv_vxhs);
> +}
> +
> +block_init(bdrv_vxhs_init);
> diff --git a/block/vxhs.h b/block/vxhs.h
> new file mode 100644
> index 0000000..2f3e4de
> --- /dev/null
> +++ b/block/vxhs.h
> @@ -0,0 +1,236 @@
> +/*
> + * QEMU Block driver for Veritas HyperScale (VxHS)
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#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 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                  \
> +    (qnio_ck_initialize_lock())
> +#define VXHS_SPIN_LOCK(lock)                  \
> +    (qnio_ck_spin_lock(lock))
> +#define VXHS_SPIN_UNLOCK(lock)                \
> +    (qnio_ck_spin_unlock(lock))
> +#define VXHS_SPIN_LOCK_DESTROY(lock)          \
> +    (qnio_ck_destroy_lock(lock))
> +
> +typedef enum {
> +    VXHS_IO_INPROGRESS,
> +    VXHS_IO_COMPLETED,
> +    VXHS_IO_ERROR
> +} VXHSIOState;
> +
> +
> +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 VXHS_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)
> +
> +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);
> +
> +/*
> + * 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[VXHS_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; /* Currently for debugging */
> +    char                    *vdisk_guid;
> +} BDRVVXHSState;
> +
> +void bdrv_vxhs_init(void);
> +void *vxhs_setup_qnio(void);
> +void vxhs_iio_callback(uint32_t rfd, uint32_t reason, void *ctx, void *m);
> +void vxhs_aio_event_reader(void *opaque);
> +void vxhs_complete_aio(VXHSAIOCB *acb, BDRVVXHSState *s);
> +int vxhs_aio_flush_cb(void *opaque);
> +unsigned long vxhs_get_vdisk_stat(BDRVVXHSState *s);
> +int vxhs_open(BlockDriverState *bs, QDict *options,
> +              int bdrv_flags, Error **errp);
> +void vxhs_close(BlockDriverState *bs);
> +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);
> +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);
> +int64_t vxhs_getlength(BlockDriverState *bs);
> +void vxhs_inc_vdisk_iocount(void *ptr, uint32_t delta);
> +void vxhs_dec_vdisk_iocount(void *ptr, uint32_t delta);
> +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);
> +int vxhs_dec_and_get_acb_segment_count(void *ptr, int count);
> +void vxhs_set_acb_buffer(void *ptr, void *buffer);
> +int vxhs_failover_io(BDRVVXHSState *s);
> +int vxhs_reopen_vdisk(BDRVVXHSState *s, int hostinfo_index);
> +int vxhs_switch_storage_agent(BDRVVXHSState *s);
> +int vxhs_handle_queued_ios(BDRVVXHSState *s);
> +int vxhs_restart_aio(VXHSAIOCB *acb);
> +void vxhs_fail_aio(VXHSAIOCB *acb, int err);
> +void vxhs_failover_ioctl_cb(int res, void *ctx);
> +
> +
> +#endif
> diff --git a/configure b/configure
> index 5a9bda1..340824c 100755
> --- a/configure
> +++ b/configure
> @@ -320,6 +320,7 @@ vhdx=""
>  numa=""
>  tcmalloc="no"
>  jemalloc="no"
> +vxhs=""
>  
>  # 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
> @@ -4555,6 +4562,43 @@ if do_cc -nostdlib -Wl,-r -Wl,--no-relax -o $TMPMO 
> $TMPO; then
>  fi
>  
>  ##########################################
> +# Veritas HyperScale block driver VxHS
> +# Check if libqnio is installed
> +if test "$vxhs" != "no" ; then
> +  cat > $TMPC <<EOF
> +#include <stdio.h>
> +#include <qnio/qnio_api.h>
> +
> +void vxhs_inc_acb_segment_count(void *acb, int count);
> +void vxhs_dec_acb_segment_count(void *acb, int count);
> +void vxhs_set_acb_buffer(void *ptr, void *buffer);
> +
> +void vxhs_inc_acb_segment_count(void *ptr, int count)
> +{
> +}
> +void vxhs_dec_acb_segment_count(void *ptr, int count)
> +{
> +}
> +void vxhs_set_acb_buffer(void *ptr, void *buffer)
> +{
> +}
> +int main(void) {
> +    qnio_ck_initialize_lock();
> +    return 0;
> +}
> +EOF
> +  vxhs_libs="-lqnioshim -lqnio"
> +  if compile_prog "" "$vxhs_libs" ; then
> +    vxhs=yes
> +  else
> +    if test "$vxhs" = "yes" ; then
> +      feature_not_found "vxhs block device" "Install libqnio. See github"
> +    fi
> +    vxhs=no
> +  fi
> +fi
> +
> +##########################################
>  # End of CC checks
>  # After here, no more $cc or $ld runs
>  
> @@ -4920,6 +4964,7 @@ echo "NUMA host support $numa"
>  echo "tcmalloc support  $tcmalloc"
>  echo "jemalloc support  $jemalloc"
>  echo "avx2 optimization $avx2_opt"
> +echo "VxHS block device $vxhs"
>  
>  if test "$sdl_too_old" = "yes"; then
>  echo "-> Your SDL version is too old - please upgrade to have SDL support"
> @@ -5507,6 +5552,12 @@ 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" >> $config_host_mak
> +  echo "VXHS_CFLAGS=$vxhs_cflags" >> $config_host_mak
> +  echo "VXHS_LIBS=$vxhs_libs" >> $config_host_mak
> +fi
> +
>  if test "$tcg_interpreter" = "yes"; then
>    QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/tci $QEMU_INCLUDES"
>  elif test "$ARCH" = "sparc64" ; then
> 



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