2010/11/29 Stefan Hajnoczi <stefanha@xxxxxxxxx>:
> On Thu, Nov 25, 2010 at 6:06 AM, Yoshiaki Tamura
> <tamura.yoshiaki@xxxxxxxxxxxxx> wrote:
>> event-tap controls when to start FT transaction, and provides proxy
>> functions to called from net/block devices. While FT transaction, it
>> queues up net/block requests, and flush them when the transaction gets
>> completed.
>>
>> Signed-off-by: Yoshiaki Tamura <tamura.yoshiaki@xxxxxxxxxxxxx>
>> Signed-off-by: OHMURA Kei <ohmura.kei@xxxxxxxxxxxxx>
>> ---
>> Makefile.target | 1 +
>> block.h | 9 +
>> event-tap.c | 794 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> event-tap.h | 34 +++
>> net.h | 4 +
>> net/queue.c | 1 +
>> 6 files changed, 843 insertions(+), 0 deletions(-)
>> create mode 100644 event-tap.c
>> create mode 100644 event-tap.h
>
> event_tap_state is checked at the beginning of several functions. If
> there is an unexpected state the function silently returns. Should
> these checks really be assert() so there is an abort and backtrace if
> the program ever reaches this state?
I'm wondering whether abort is too strong, but I think you're
right because stopping Kemari may not be enough as an error
handling.
>
>> +typedef struct EventTapBlkReq {
>> + char *device_name;
>> + int num_reqs;
>> + int num_cbs;
>> + bool is_multiwrite;
>
> Is multiwrite logging necessary? If event tap is called from within
> the block layer then multiwrite is turned into one or more
> bdrv_aio_writev() calls.
If we move event-tap into block layer, I guess it won't be
necessary.
>> +static void event_tap_replay(void *opaque, int running, int reason)
>> +{
>> + EventTapLog *log, *next;
>> +
>> + if (!running) {
>> + return;
>> + }
>> +
>> + if (event_tap_state != EVENT_TAP_LOAD) {
>> + return;
>> + }
>> +
>> + event_tap_state = EVENT_TAP_REPLAY;
>> +
>> + QTAILQ_FOREACH(log, &event_list, node) {
>> + EventTapBlkReq *blk_req;
>> +
>> + /* event resume */
>> + switch (log->mode & ~EVENT_TAP_TYPE_MASK) {
>> + case EVENT_TAP_NET:
>> + event_tap_net_flush(&log->net_req);
>> + break;
>> + case EVENT_TAP_BLK:
>> + blk_req = &log->blk_req;
>> + if ((log->mode & EVENT_TAP_TYPE_MASK) == EVENT_TAP_IOPORT) {
>> + switch (log->ioport.index) {
>> + case 0:
>> + cpu_outb(log->ioport.address, log->ioport.data);
>> + break;
>> + case 1:
>> + cpu_outw(log->ioport.address, log->ioport.data);
>> + break;
>> + case 2:
>> + cpu_outl(log->ioport.address, log->ioport.data);
>> + break;
>> + }
>> + } else {
>> + /* EVENT_TAP_MMIO */
>> + cpu_physical_memory_rw(log->mmio.address,
>> + log->mmio.buf,
>> + log->mmio.len, 1);
>> + }
>> + break;
>
> Why are net tx packets replayed at the net level but blk requests are
> replayed at the pio/mmio level?
>
> I expected everything to replay either as pio/mmio or as net/block.
It's my mistake, sorry about that. We're just in way of moving
replay from pio/mmio to net/block, and I mixed up. I'll revert
it to pio/mmio replay in the next spin.
BTW, I would like to ask a question regarding this. There is a
callback which net/block calls after processing the requests, and
is there a clean way to set this callback on the failovered
host upon replay?
>> +static void event_tap_blk_load(QEMUFile *f, EventTapBlkReq *blk_req)
>> +{
>> + BlockRequest *req;
>> + ram_addr_t page_addr;
>> + int i, j, len;
>> +
>> + len = qemu_get_byte(f);
>> + blk_req->device_name = qemu_malloc(len + 1);
>> + qemu_get_buffer(f, (uint8_t *)blk_req->device_name, len);
>> + blk_req->device_name[len] = '\0';
>> + blk_req->num_reqs = qemu_get_byte(f);
>> +
>> + for (i = 0; i < blk_req->num_reqs; i++) {
>> + req = &blk_req->reqs[i];
>> + req->sector = qemu_get_be64(f);
>> + req->nb_sectors = qemu_get_be32(f);
>> + req->qiov = qemu_malloc(sizeof(QEMUIOVector));
>
> It would make sense to have common QEMUIOVector load/save functions
> instead of inlining this code here.
OK.
>> +static int event_tap_load(QEMUFile *f, void *opaque, int version_id)
>> +{
>> + EventTapLog *log, *next;
>> + int mode;
>> +
>> + event_tap_state = EVENT_TAP_LOAD;
>> +
>> + QTAILQ_FOREACH_SAFE(log, &event_list, node, next) {
>> + QTAILQ_REMOVE(&event_list, log, node);
>> + event_tap_free_log(log);
>> + }
>> +
>> + /* loop until EOF */
>> + while ((mode = qemu_get_byte(f)) != 0) {
>> + EventTapLog *log = event_tap_alloc_log();
>> +
>> + log->mode = mode;
>> + switch (log->mode & EVENT_TAP_TYPE_MASK) {
>> + case EVENT_TAP_IOPORT:
>> + event_tap_ioport_load(f, &log->ioport);
>> + break;
>> + case EVENT_TAP_MMIO:
>> + event_tap_mmio_load(f, &log->mmio);
>> + break;
>> + case 0:
>> + DPRINTF("No event\n");
>> + break;
>> + default:
>> + fprintf(stderr, "Unknown state %d\n", log->mode);
>> + return -1;
>
> log is leaked here...
Oops:(
>
>> + }
>> +
>> + switch (log->mode & ~EVENT_TAP_TYPE_MASK) {
>> + case EVENT_TAP_NET:
>> + event_tap_net_load(f, &log->net_req);
>> + break;
>> + case EVENT_TAP_BLK:
>> + event_tap_blk_load(f, &log->blk_req);
>> + break;
>> + default:
>> + fprintf(stderr, "Unknown state %d\n", log->mode);
>> + return -1;
>
> ...and here.
Oops again:(
Will fix them.
Yoshi
>
> Stefan
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