Re: [Qemu-devel] [PATCH v2] sheepdog: add reopen support

[Jeff Cody <jcody@redhat.com>]

On Thu, Aug 27, 2015 at 10:54:01AM +0800, Liu Yuan wrote:
> From: Liu Yuan <liuyuan@cmss.chinamobile.com>
> 
> With reopen supported, block-commit (and offline commit) is now supported for
> image files whose base image uses the Sheepdog protocol driver.
> 
> Cc: qemu-devel@nongnu.org
> Cc: Jeff Cody <jcody@redhat.com>
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Liu Yuan <liuyuan@cmss.chinamobile.com>
> ---
> v2:
>  - free AioHandler [Jeff Cody]
> 
>  block/sheepdog.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 75 insertions(+)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index 9585beb..e54add4 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -377,6 +377,11 @@ typedef struct BDRVSheepdogState {
>      QLIST_HEAD(inflight_aiocb_head, SheepdogAIOCB) inflight_aiocb_head;
>  } BDRVSheepdogState;
>  
> +typedef struct BDRVSheepdogReopenState {
> +    int fd;
> +    int cache_flags;
> +} BDRVSheepdogReopenState;
> +
>  static const char * sd_strerror(int err)
>  {
>      int i;
> @@ -1486,6 +1491,67 @@ out:
>      return ret;
>  }
>  
> +static int sd_reopen_prepare(BDRVReopenState *state, BlockReopenQueue *queue,
> +                             Error **errp)
> +{
> +    BDRVSheepdogState *s = state->bs->opaque;
> +    BDRVSheepdogReopenState *re_s;
> +    int ret = 0;
> +
> +    re_s = state->opaque = g_new0(BDRVSheepdogReopenState, 1);
> +
> +    if (state->flags & BDRV_O_NOCACHE) {
> +        re_s->cache_flags = SD_FLAG_CMD_DIRECT;
> +    }

In sd_open(), the s->cache_flag is set to SD_FLAG_CMD_CACHE by
default, and then overwritten if BDRV_O_NOCACHE is set.  Do we want
that same behavior here?

(Sorry I didn't ask this the first time around)

> +
> +    re_s->fd = get_sheep_fd(s, errp);
> +    if (re_s->fd < 0) {
> +        ret = re_s->fd;
> +        return ret;
> +    }
> +
> +    return ret;
> +}
> +
> +static void sd_reopen_commit(BDRVReopenState *state)
> +{
> +    BDRVSheepdogReopenState *re_s = state->opaque;
> +    BDRVSheepdogState *s = state->bs->opaque;
> +
> +    if (s->fd) {
> +        aio_set_fd_handler(s->aio_context, s->fd, NULL, NULL, NULL);
> +        closesocket(s->fd);
> +    }
> +
> +    s->fd = re_s->fd;
> +    s->cache_flags = re_s->cache_flags;
> +
> +    g_free(state->opaque);
> +    state->opaque = NULL;
> +
> +    return;
> +}
> +
> +static void sd_reopen_abort(BDRVReopenState *state)
> +{
> +    BDRVSheepdogReopenState *re_s = state->opaque;
> +    BDRVSheepdogState *s = state->bs->opaque;
> +
> +    if (re_s == NULL) {
> +        return;
> +    }
> +
> +    if (re_s->fd) {
> +        aio_set_fd_handler(s->aio_context, re_s->fd, NULL, NULL, NULL);
> +        closesocket(re_s->fd);
> +    }
> +
> +    g_free(state->opaque);
> +    state->opaque = NULL;
> +
> +    return;
> +}
> +
>  static int do_sd_create(BDRVSheepdogState *s, uint32_t *vdi_id, int snapshot,
>                          Error **errp)
>  {
> @@ -2703,6 +2769,9 @@ static BlockDriver bdrv_sheepdog = {
>      .instance_size  = sizeof(BDRVSheepdogState),
>      .bdrv_needs_filename = true,
>      .bdrv_file_open = sd_open,
> +    .bdrv_reopen_prepare    = sd_reopen_prepare,
> +    .bdrv_reopen_commit     = sd_reopen_commit,
> +    .bdrv_reopen_abort      = sd_reopen_abort,
>      .bdrv_close     = sd_close,
>      .bdrv_create    = sd_create,
>      .bdrv_has_zero_init = bdrv_has_zero_init_1,
> @@ -2736,6 +2805,9 @@ static BlockDriver bdrv_sheepdog_tcp = {
>      .instance_size  = sizeof(BDRVSheepdogState),
>      .bdrv_needs_filename = true,
>      .bdrv_file_open = sd_open,
> +    .bdrv_reopen_prepare    = sd_reopen_prepare,
> +    .bdrv_reopen_commit     = sd_reopen_commit,
> +    .bdrv_reopen_abort      = sd_reopen_abort,
>      .bdrv_close     = sd_close,
>      .bdrv_create    = sd_create,
>      .bdrv_has_zero_init = bdrv_has_zero_init_1,
> @@ -2769,6 +2841,9 @@ static BlockDriver bdrv_sheepdog_unix = {
>      .instance_size  = sizeof(BDRVSheepdogState),
>      .bdrv_needs_filename = true,
>      .bdrv_file_open = sd_open,
> +    .bdrv_reopen_prepare    = sd_reopen_prepare,
> +    .bdrv_reopen_commit     = sd_reopen_commit,
> +    .bdrv_reopen_abort      = sd_reopen_abort,
>      .bdrv_close     = sd_close,
>      .bdrv_create    = sd_create,
>      .bdrv_has_zero_init = bdrv_has_zero_init_1,
> -- 
> 1.9.1
>