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Re: [Qemu-devel] [PATCH v4 RFC] block/vxhs: Initial commit to add Verita


From: ashish mittal
Subject: Re: [Qemu-devel] [PATCH v4 RFC] block/vxhs: Initial commit to add Veritas HyperScale VxHS block device support
Date: Wed, 7 Sep 2016 15:32:47 -0700

Hi Jeff,

Thank you for the comments and corrections.

I have submitted a v5 patch after incorporating most of your review
comments. Please find details in-line.

Thanks,
Ashish

On Tue, Aug 30, 2016 at 10:35 AM, Jeff Cody <address@hidden> wrote:
>
> First-pass-over-the-code review:
>
> On Mon, Aug 22, 2016 at 11:56:30PM -0700, Ashish Mittal wrote:
>> This patch adds support for a new block device type called "vxhs".
>> Source code for the library that this code loads can be downloaded from:
>> https://github.com/MittalAshish/libqnio.git
>>
>> Sample command line using JSON syntax:
>> ./qemu-system-x86_64 -name instance-00000008 -S -vnc 0.0.0.0:0 -k en-us -vga 
>> cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 -msg 
>> timestamp=on 
>> 'json:{"driver":"vxhs","vdisk_id":"{c3e9095a-a5ee-4dce-afeb-2a59fb387410}","server":[{"host":"172.172.17.4","port":"9999"},{"host":"172.172.17.2","port":"9999"}]}'
>>
>> Sample command line using URI syntax:
>> qemu-img convert -f raw -O raw -n 
>> /var/lib/nova/instances/_base/0c5eacd5ebea5ed914b6a3e7b18f1ce734c386ad 
>> vxhs://192.168.0.1:9999/%7Bc6718f6b-0401-441d-a8c3-1f0064d75ee0%7D
>>
>
> Is there a reference specification for vxhs available?  If so, the commit
> message would be a good place to drop a link.
>

We don't have a reference specification doc yet. Although, I will
shortly be adding a test program to libqnio that can be used to
test/demo basic libqnio IO transfer.

>> Signed-off-by: Ashish Mittal <address@hidden>
>> ---
>> v3 changelog:
>> =============
>> (1) Reworked QAPI/JSON parsing.
>> (2) Reworked URI parsing as suggested by Kevin.
>> (3) Fixes per review comments from Stefan on v1.
>> (4) Fixes per review comments from Daniel on v3.
>>
>>  block/Makefile.objs |    2 +
>>  block/trace-events  |   41 ++
>>  block/vxhs.c        | 1304 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>>  block/vxhs.h        |  237 ++++++++++
>>  configure           |   50 ++
>>  5 files changed, 1634 insertions(+)
>>  create mode 100644 block/vxhs.c
>>  create mode 100644 block/vxhs.h
>>
>> diff --git a/block/Makefile.objs b/block/Makefile.objs
>> index 2593a2f..5f83305 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
>>
>> @@ -43,3 +44,4 @@ block-obj-m        += dmg.o
>>  dmg.o-libs         := $(BZIP2_LIBS)
>>  qcow.o-libs        := -lz
>>  linux-aio.o-libs   := -laio
>> +vxhs.o-libs        := $(VXHS_LIBS)
>> diff --git a/block/trace-events b/block/trace-events
>> index 05fa13c..06c6d8c 100644
>> --- a/block/trace-events
>> +++ b/block/trace-events
>> @@ -114,3 +114,44 @@ qed_aio_write_data(void *s, void *acb, int ret, 
>> uint64_t offset, size_t len) "s
>>  qed_aio_write_prefill(void *s, void *acb, uint64_t start, size_t len, 
>> uint64_t offset) "s %p acb %p start %"PRIu64" len %zu offset %"PRIu64
>>  qed_aio_write_postfill(void *s, void *acb, uint64_t start, size_t len, 
>> uint64_t offset) "s %p acb %p start %"PRIu64" len %zu offset %"PRIu64
>>  qed_aio_write_main(void *s, void *acb, int ret, uint64_t offset, size_t 
>> len) "s %p acb %p ret %d offset %"PRIu64" len %zu"
>> +
>> +# block/vxhs.c
>> +vxhs_bdrv_init(const char c) "Registering VxHS AIO driver%c"
>> +vxhs_iio_callback(int error, int reason) "ctx is NULL: error %d, reason %d"
>> +vxhs_setup_qnio(void *s) "Context to HyperScale IO manager = %p"
>> +vxhs_setup_qnio_nwerror(char c) "Could not initialize the network channel. 
>> Bailing out%c"
>> +vxhs_iio_callback_iofail(int err, int reason, void *acb, int seg) 
>> "Read/Write failed: error %d, reason %d, acb %p, segment %d"
>> +vxhs_iio_callback_retry(char *guid, void *acb) "vDisk %s, added acb %p to 
>> retry queue (5)"
>> +vxhs_iio_callback_chnlfail(int error) "QNIO channel failed, no i/o (%d)"
>> +vxhs_iio_callback_fail(int r, void *acb, int seg, uint64_t size, int err) " 
>> ALERT: reason = %d , acb = %p, acb->segments = %d, acb->size = %lu Error = 
>> %d"
>> +vxhs_fail_aio(char * guid, void *acb) "vDisk %s, failing acb %p"
>> +vxhs_iio_callback_ready(char *vd, int err) "async vxhs_iio_callback: 
>> IRP_VDISK_CHECK_IO_FAILOVER_READY completed for vdisk %s with error %d"
>> +vxhs_iio_callback_chnfail(int err, int error) "QNIO channel failed, no i/o 
>> %d, %d"
>> +vxhs_iio_callback_unknwn(int opcode, int err) "unexpected opcode %d, errno 
>> %d"
>> +vxhs_open_fail(int ret) "Could not open the device. Error = %d"
>> +vxhs_open_epipe(char c) "Could not create a pipe for device. Bailing out%c"
>> +vxhs_aio_rw(char *guid, int iodir, uint64_t size, uint64_t offset) "vDisk 
>> %s, vDisk device is in failed state iodir = %d size = %lu offset = %lu"
>> +vxhs_aio_rw_retry(char *guid, void *acb, int queue) "vDisk %s, added acb %p 
>> to retry queue(%d)"
>> +vxhs_aio_rw_invalid(int req) "Invalid I/O request iodir %d"
>> +vxhs_aio_rw_ioerr(char *guid, int iodir, uint64_t size, uint64_t off, void 
>> *acb, int seg, int ret, int err) "IO ERROR (vDisk %s) FOR : Read/Write = %d 
>> size = %lu offset = %lu ACB = %p Segments = %d. Error = %d, errno = %d"
>> +vxhs_co_flush(char *guid, int ret, int err) "vDisk (%s) Flush ioctl failed 
>> ret = %d errno = %d"
>> +vxhs_get_vdisk_stat_err(char *guid, int ret, int err) "vDisk (%s) stat 
>> ioctl failed, ret = %d, errno = %d"
>> +vxhs_get_vdisk_stat(char *vdisk_guid, uint64_t vdisk_size) "vDisk %s stat 
>> ioctl returned size %lu"
>> +vxhs_switch_storage_agent(char *ip, char *guid) "Query host %s for vdisk %s"
>> +vxhs_switch_storage_agent_failed(char *ip, char *guid, int res, int err) 
>> "Query to host %s for vdisk %s failed, res = %d, errno = %d"
>> +vxhs_failover_ioctl_cb(char *ip, char *guid) "Switched to storage server 
>> host-IP %s for vdisk %s"
>> +vxhs_failover_ioctl_cb_retry(char *guid) "failover_ioctl_cb: keep looking 
>> for io target for vdisk %s"
>> +vxhs_failover_io(char *vdisk) "I/O Failover starting for vDisk %s"
>> +vxhs_reopen_vdisk(char *ip) "Failed to connect to storage agent on host-ip 
>> %s"
>> +vxhs_reopen_vdisk_openfail(char *fname) "Failed to open vdisk device: %s"
>> +vxhs_handle_queued_ios(void *acb, int res) "Restarted acb %p res %d"
>> +vxhs_restart_aio(int dir, int res, int err) "IO ERROR FOR: Read/Write = %d 
>> Error = %d, errno = %d"
>> +vxhs_complete_aio(void *acb, uint64_t ret) "aio failed acb %p ret %ld"
>> +vxhs_aio_rw_iofail(char *guid) "vDisk %s, I/O operation failed."
>> +vxhs_aio_rw_devfail(char *guid, int dir, uint64_t size, uint64_t off) 
>> "vDisk %s, vDisk device failed iodir = %d size = %lu offset = %lu"
>> +vxhs_parse_uri_filename(const char *filename) "URI passed via 
>> bdrv_parse_filename %s"
>> +vxhs_qemu_init_vdisk(const char *vdisk_id) "vdisk_id from json %s"
>> +vxhs_qemu_init_numservers(int num_servers) "Number of servers passed = %d"
>> +vxhs_parse_uri_hostinfo(int num, char *host, int port) "Host %d: IP %s, 
>> Port %d"
>> +vxhs_qemu_init(char *of_vsa_addr, int port) "Adding host %s:%d to 
>> BDRVVXHSState"
>> +vxhs_qemu_init_filename(const char *filename) "Filename passed as %s"
>> diff --git a/block/vxhs.c b/block/vxhs.c
>> new file mode 100644
>> index 0000000..32c37c5
>> --- /dev/null
>> +++ b/block/vxhs.c
>> @@ -0,0 +1,1304 @@
>> +/*
>> + * QEMU Block driver for Veritas HyperScale (VxHS)
>> + *
>
> Another good place for a link to the specification, if available.
>
>
>> + * 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);
>> +    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;
>> +}
>
> Unused function?
>

Yes, it is unused. Sorry I forgot to remove it from V5. Will remember
to remove in the next iteration.

>> +
>> +void vxhs_set_acb_buffer(void *ptr, void *buffer)
>> +{
>> +    VXHSAIOCB *acb = ptr;
>> +
>> +    acb->buffer = buffer;
>> +}
>> +
>
> Unused function?
>

This is called from within libqnio.

> (There are several unused functions - are there other patches that use these
> functions?  Maybe I missed them on the list.  If not, and they are for
> future work, maybe it would be best to introduce these functions in the
> patch series that will actually use them. It will cut down on the amount of
> code to be reviewed, and since it is not exercised it can't be verified
> anyway).
>

Removed all unused functions, except vxhs_dec_and_get_acb_segment_count().

>> +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);
>> +}
>> +
>> +uint32_t vxhs_get_vdisk_iocount(void *ptr)
>> +{
>> +    BDRVVXHSState *s = ptr;
>> +    uint32_t count = 0;
>> +
>> +    VXHS_SPIN_LOCK(s->vdisk_lock);
>> +    count = s->vdisk_aio_count;
>> +    VXHS_SPIN_UNLOCK(s->vdisk_lock);
>> +
>> +    return count;
>> +}
>
> Function only used by another function that is not called from anywhere.
>
>

Removed.

>> +
>> +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 = qemu_iio_extract_msg_error(m);
>> +        opcode = 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 = 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);
>> +}
>> +
>> +/*
>> + * QEMU calls this to check if there are any pending IO on vDisk.
>> + * It will wait in a loop until all the AIOs are completed.
>> + */
>> +int vxhs_aio_flush_cb(void *opaque)
>> +{
>> +    BDRVVXHSState *s = opaque;
>> +
>> +    return vxhs_get_vdisk_iocount(s);
>> +}
>
> Unused function.
>
>

Removed.

>> +
>> +/*
>> + * This will be called by QEMU while booting for each vDisk.
>> + * 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
>> + * do IO on vDisk. It parses the URI, gets the hostname, vDisk
>> + * path and then sets HyperScale event handler to QEMU.
>> + */
>> +void *vxhs_setup_qnio(void)
>> +{
>> +    void *qnio_ctx = NULL;
>> +
>> +    qnio_ctx = qemu_iio_init(vxhs_iio_callback);
>
> One concern with this callback function - when does it get called?  I am
> assuming that qemu_iio_init() is running threads / processes in the
> background, so this callback could happen at anytime.
>
> (I'll discuss my specific concern later, in vxhs_failover_ioctl_cb())
>
>
>

Yes, that is correct. vxhs_setup_qnio() is called from the threads
running in libqnio.



> An aside:
>
> It is odd that the qnio library is using a qemu_ prefix for functions.
> Seems like a good way to run into issues later, especially with relatively
> generic function names such as 'qemu_ck_spin_lock()'. Consider that most
> developers / maintainers are probably not going to compile in vxhs given the
> external library dependence without a specific reason, so name collisions
> could sneak in.
>
> 'nm -g libqnioshim.so | grep qemu_' shows a few that give me pause:
>
> 0000000000004d07 T qemu_calculate_iovec_size
> 000000000000663d T qemu_ck_destroy_lock
> 00000000000065cf T qemu_ck_initialize_lock
> 00000000000065f7 T qemu_ck_spin_lock
> 000000000000661a T qemu_ck_spin_unlock
> 0000000000004dfb T qemu_convert_iovector_to_buffer
> 0000000000004d63 T qemu_copy_iov_to_buffer
> 0000000000005f2f T qemu_extract_flush_response
> 0000000000005c89 T qemu_extract_geometry_from_json
> 0000000000005a78 T qemu_extract_size_from_json
> 0000000000004f40 T qemu_is_iovector_read_aligned
>
>

Replaced all qemu_ prefixed symbols within qnio.

>
>> +
>> +    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 *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)) {
>> +            qdict_put(options, "vdisk_id", qstring_from_str(uri->path));
>> +        }
>> +
>> +        trace_vxhs_parse_uri_hostinfo(i + 1, uri->server, uri->port);
>> +        g_free(hoststr);
>> +        g_free(portstr);
>> +        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;
>> +    const char *vxhs_filename;
>> +    char *of_vsa_addr = NULL;
>> +    Error *local_err = NULL;
>> +    const char *ptr = NULL;
>
> ptr does not need to be initialized to NULL here.  I also recommend using a
> more descriptive name like 'vdisk_id_opt' over something generic like 'ptr'.
>

Fixed.


>> +    char *file_name = NULL;
>> +    size_t num_servers;
>> +    char *str = NULL;
>> +    QemuOpts *opts;
>> +    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);
>> +    }
>> +
>> +    ptr = qemu_opt_get(opts, VXHS_OPT_VDISK_ID);
>> +    if (!ptr) {
>> +        error_setg(&local_err, QERR_MISSING_PARAMETER, VXHS_OPT_VDISK_ID);
>> +        ret = -EINVAL;
>> +        goto out;
>> +    }
>> +    s->vdisk_guid = g_strdup(ptr);
>
> This is never freed anywhere.
>

Now freed on error conditions and in vxhs_close().

>> +    trace_vxhs_qemu_init_vdisk(ptr);
>> +
>> +    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;
>> +    }
>> +    trace_vxhs_qemu_init_numservers(num_servers);
>> +
>> +    qemu_opts_del(opts);
>> +
>> +    for (i = 0; i < num_servers; i++) {
>
> s->vdisk_hostinfo[] is an array with MAX_HOSTS (4) as a size.  There is no
> bounds checking on num_servers, which is an issue: we can easily blow
> past this.
>
> In general, for any parameter supplied by a user, or read from a file /
> protocol / etc, we need to do appropriate bounds checking to prevent
> potential CVEs.
>

Fixed.

>> +        str = g_strdup_printf(VXHS_OPT_SERVER"%d.", i);
>> +        qdict_extract_subqdict(options, &backing_options, str);
>> +
>> +        /* create opts info from runtime_tcp_opts list */
>> +        opts = qemu_opts_create(&runtime_tcp_opts, NULL, 0, &error_abort);
>> +        qemu_opts_absorb_qdict(opts, backing_options, &local_err);
>> +        if (local_err) {
>> +            ret = -EINVAL;
>> +            qemu_opts_del(opts);
>> +            goto out;
>> +        }
>> +
>> +        s->vdisk_hostinfo[i].hostip = g_strdup(qemu_opt_get(opts,
>> +                                                            VXHS_OPT_HOST));
>
> This is never freed anywhere.
>

Now freed on error and vxhs_close().

>> +        s->vdisk_hostinfo[i].port = g_ascii_strtoll(qemu_opt_get(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);
>> +        qemu_opts_del(opts);
>> +    }
>> +
>> +    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 = qemu_open_iio_conn(global_qnio_ctx, of_vsa_addr, 0);
>> +    if (*cfd < 0) {
>> +        error_setg(&local_err, "Failed qemu_open_iio_conn");
>> +        ret = -EIO;
>> +        goto out;
>> +    }
>> +    *rfd = qemu_iio_devopen(global_qnio_ctx, *cfd, file_name, 0);
>> +    if (*rfd < 0) {
>> +        error_setg(&local_err, "Failed qemu_iio_devopen");
>> +        ret = -EIO;
>> +        goto out;
>> +    }
>> +
>> +out:
>> +    g_free(file_name);
>> +    g_free(of_vsa_addr);
>> +    if (str) {
>> +        qdict_del(backing_options, str);
>> +        g_free(str);
>> +    }
>> +
>> +    if (ret < 0) {
>> +        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 qemu_rfd = -1;
>> +    int ret = 0;
>> +
>> +    ret = vxhs_qemu_init(options, s, &qemu_qnio_cfd, &qemu_rfd, errp);
>> +    if (ret < 0) {
>> +        trace_vxhs_open_fail(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);
>> +
>> +    /*
>> +     * 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 out;
>> +    }
>> +    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;
>> +
>> +out:
>> +    if (s->vdisk_hostinfo[0].vdisk_rfd >= 0) {
>> +        qemu_iio_devclose(s->qnio_ctx, 0,
>> +                                 s->vdisk_hostinfo[0].vdisk_rfd);
>> +    }
>> +    /* never close qnio_cfd */
>
> Surely we want to be able to close it at some point... or does the qnio
> library take care of that cleanup somewhere/sometime?
>
>

Changed to close channel fd on error conditions, vxhs_close() and
vxhs_reopen_vdisk().


>> +    trace_vxhs_open_fail(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 = arg;
>> +    BlockDriverState *bs = acb->common.bs;
>> +    BDRVVXHSState *s = bs->opaque;
>> +    int rv;
>> +
>> +    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();
>> +    }
>> +}
>
> Another unused function.
>

Removed.


>> +
>> +/*
>> + * 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 = 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);
>> +            break;
>> +    case VDISK_AIO_READ:
>> +            vxhs_inc_acb_segment_count(acb, 1);
>> +            ret = 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);
>> +            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;
>> +
>> +    ret = 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.
>
> I'm not sure I understand here.  Are you saying the qemu_iio_ioctl() call
> above is a noop?
>

Yes, qemu_iio_ioctl(VDISK_AIO_FLUSH) is only a place-holder at present
in case we later want to add some functionality to it. I have now
added a comment to this affect to avoid any confusion.

>> +         *
>> +         * 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;
>> +    unsigned long vdisk_size = 0;
>> +    int ret = 0;
>> +
>> +    ret = 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) {
>> +        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;
>> +    unsigned long vdisk_size = 0;
>> +
>> +    if (s->vdisk_size > 0) {
>> +        vdisk_size = s->vdisk_size;
>
> s->vdisk_size is int64_t, vdisk_size is unsigned long.  On 32-bit platforms,
> I believe unsigned long is only 32-bits, so this assignment is problematic.
>
> What is the maximum disk size for vxhs?
>
> (this comment applies to all the vdisk_size usage, but I'll only mention it
> here)
>

Changed to int64_t in all places. The code does not place any
restriction on the maximum size of the vdisk.

>> +    } 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;
>> +        }
>> +    }
>> +
>> +    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;
>> +
>> +    close(s->fds[VDISK_FD_READ]);
>> +    close(s->fds[VDISK_FD_WRITE]);
>> +
>> +    /*
>> +     * never close channel - not ref counted, will
>> +     * close for all vdisks
>> +     */
>> +    if (s->vdisk_hostinfo[s->vdisk_cur_host_idx].vdisk_rfd >= 0) {
>> +        qemu_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;
>> +    }
>> +
>> +    /*
>> +     * TODO: Verify that all the resources were relinguished.
>> +     */
>
> Which resources?  Allocated here in the driver, or stuff in libqnio?
>

The comment was for all resources allocated within vxhs.c.
Added code to free all allocated memory and fds on close.


>> +}
>> +
>> +/*
>> + * 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 = qemu_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 qemu_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) {
>
> This function, vxhs_failover_ioctrl_cb(), is called from the external
> library callback, in addition to QEMU itself (i.e., vxhs_aio_rw).  This
> makes me concerned that we may have (or be able to induce) an unsafe race
> condition when incrementing the vdisk_ask_failover_id array index.
>

vxhs_failover_ioctl_cb()  can be called from the callback
vxhs_iio_callback() case IRP_VDISK_CHECK_IO_FAILOVER_READY in response
to the qnio_iio_ioctl(VDISK_CHECK_IO_FAILOVER_READY)

This ioctl qnio_iio_ioctl(VDISK_CHECK_IO_FAILOVER_READY) is only
called from within vxhs_switch_storage_agent()

A direct call to vxhs_failover_ioctl_cb() is only issued from the same
function vxhs_switch_storage_agent() on an "else" condition. So
vxhs_failover_ioctl_cb() can only be called from a single thread
context either in response to the ioctl, or directly. We should be
safe here, but thanks for pointing it out!

>> +            /* 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;
>> +
>> +    /*
>> +     * 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) {
>> +        qemu_iio_devclose(s->qnio_ctx, 0,
>> +                                 s->vdisk_hostinfo[index].vdisk_rfd);
>> +        s->vdisk_hostinfo[index].vdisk_rfd = -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 =
>> +                qemu_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 =
>> +            qemu_iio_devopen(global_qnio_ctx,
>> +             s->vdisk_hostinfo[index].qnio_cfd, file_name, 0);
>> +    if (s->vdisk_hostinfo[index].vdisk_rfd < 0) {
>> +        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 = 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 = 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);
>> +        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..38e0165
>> --- /dev/null
>> +++ b/block/vxhs.h
>> @@ -0,0 +1,237 @@
>> +/*
>> + * 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                  \
>> +    (qemu_ck_initialize_lock())
>> +#define VXHS_SPIN_LOCK(lock)                  \
>> +    (qemu_ck_spin_lock(lock))
>> +#define VXHS_SPIN_UNLOCK(lock)                \
>> +    (qemu_ck_spin_unlock(lock))
>> +#define VXHS_SPIN_LOCK_DESTROY(lock)          \
>> +    (qemu_ck_destroy_lock(lock))
>
> What's the value of these macros, rather than just calling the underlying
> function directly in code?
>

This way we can easily swap out CK locks with something else like
pthread_mutex if required.

>> +
>> +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 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)
>> +
>
> Many helper macros here... IMO, it decreases the readability of the code,
> and my preference is to just have the underlying code without the use of the
> macros.
>

Would like to keep this unchanged if that's OK!

>> +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[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;
>
> Is vdisk_aio_retry_qd just used for debugging purposes?  I see it
> incremented/decremented throughout the code, but no one checks it.
>

Yes, it is for debugging only. Added a comment to state the same.


>> +    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);
>> +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);
>> +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 4b808f9..c71e270 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
>> @@ -4543,6 +4550,43 @@ 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 > $TMPC <<EOF
>> +#include <stdio.h>
>> +#include <qnio/qnio_api.h>
>> +
>> +void vxhs_inc_acb_segment_count(void *acb, int count);
>> +void vxhs_dec_acb_segment_count(void *acb, int count);
>> +void vxhs_set_acb_buffer(void *ptr, void *buffer);
>> +
>> +void vxhs_inc_acb_segment_count(void *ptr, int count)
>> +{
>> +}
>> +void vxhs_dec_acb_segment_count(void *ptr, int count)
>> +{
>> +}
>> +void vxhs_set_acb_buffer(void *ptr, void *buffer)
>> +{
>> +}
>> +int main(void) {
>> +    qemu_ck_initialize_lock();
>> +    return 0;
>> +}
>> +EOF
>> +  vxhs_libs="-lqnioshim -lqnio"
>> +  if compile_prog "" "$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 $ld runs
>>
>> @@ -5488,6 +5532,12 @@ if test "$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
>
> Your configure file should indicate if vxhs is enabled or not. For instance,
> here is a snippet from where this occurs in the current configure file:
>
> [...]
> echo "NUMA host support $numa"
> echo "tcmalloc support  $tcmalloc"
> echo "jemalloc support  $jemalloc"
> echo "avx2 optimization $avx2_opt"
>
>

Fixed.

>> --
>> 2.5.5
>>
>>



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