Re: [Qemu-devel] [Fwd: [PATCH 10/22] nfs: implement .bdrv_detach/attach_aio_context()]

[Peter Lieven]

Hi Stefan,

for some reason I was not CC'ed in this email. Is there something
wrong with the maintainer info?


> ---------------------------- Original Message ----------------------------
> Subject: [Qemu-devel] [PATCH 10/22] nfs: implement
> .bdrv_detach/attach_aio_context()
> From:    "Stefan Hajnoczi" <address@hidden>
> Date:    Thu, May 1, 2014 16:54
> To:      address@hidden
> Cc:      "Kevin Wolf" <address@hidden>
>         "Shergill, Gurinder" <address@hidden>
>         "Richard W.M. Jones" <address@hidden>
>         "Stefan Hajnoczi" <address@hidden>
>         "Paolo Bonzini" <address@hidden>
>         "Vinod, Chegu" <address@hidden>
> --------------------------------------------------------------------------
> 
> Drop the assumption that we're using the main AioContext.  The following
> functions need to be converted:
> * qemu_bh_new() -> aio_bh_new()
> * qemu_aio_set_fd_handler() -> aio_set_fd_handler()
> * qemu_aio_wait() -> aio_poll()
> 
> The .bdrv_detach/attach_aio_context() interfaces also need to be
> implemented to move the fd handler from the old to the new AioContext.
> 
> Cc: Richard W.M. Jones <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
> block/nfs.c | 80
> ++++++++++++++++++++++++++++++++++++++++++-------------------
> 1 file changed, 56 insertions(+), 24 deletions(-)
> 
> diff --git a/block/nfs.c b/block/nfs.c
> index 9fa831f..33f198b 100644
> --- a/block/nfs.c
> +++ b/block/nfs.c
> @@ -40,6 +40,7 @@ typedef struct NFSClient {
>     struct nfsfh *fh;
>     int events;
>     bool has_zero_init;
> +    AioContext *aio_context;
> } NFSClient;
> 
> typedef struct NFSRPC {
> @@ -49,6 +50,7 @@ typedef struct NFSRPC {
>     struct stat *st;
>     Coroutine *co;
>     QEMUBH *bh;
> +    AioContext *aio_context;
> } NFSRPC;
> 
> static void nfs_process_read(void *arg);
> @@ -58,10 +60,11 @@ static void nfs_set_events(NFSClient *client)
> {
>     int ev = nfs_which_events(client->context);
>     if (ev != client->events) {
> -        qemu_aio_set_fd_handler(nfs_get_fd(client->context),
> -                      (ev & POLLIN) ? nfs_process_read : NULL,
> -                      (ev & POLLOUT) ? nfs_process_write : NULL,
> -                      client);
> +        aio_set_fd_handler(client->aio_context,
> +                           nfs_get_fd(client->context),
> +                           (ev & POLLIN) ? nfs_process_read : NULL,
> +                           (ev & POLLOUT) ? nfs_process_write : NULL,
> +                           client);
> 
>     }
>     client->events = ev;
> @@ -84,7 +87,8 @@ static void nfs_process_write(void *arg)
> static void nfs_co_init_task(NFSClient *client, NFSRPC *task)
> {
>     *task = (NFSRPC) {
> -        .co         = qemu_coroutine_self(),
> +        .co             = qemu_coroutine_self(),
> +        .aio_context    = client->aio_context,
>     };
> }
> 
> @@ -116,7 +120,7 @@ nfs_co_generic_cb(int ret, struct nfs_context *nfs,
> void *data,
>         error_report("NFS Error: %s", nfs_get_error(nfs));
>     }
>     if (task->co) {
> -        task->bh = qemu_bh_new(nfs_co_generic_bh_cb, task);
> +        task->bh = aio_bh_new(task->aio_context, nfs_co_generic_bh_cb,
> task);
>         qemu_bh_schedule(task->bh);
>     }
> }
> @@ -224,13 +228,34 @@ static QemuOptsList runtime_opts = {
>     },
> };
> 
> +static void nfs_detach_aio_context(BlockDriverState *bs)
> +{
> +    NFSClient *client = bs->opaque;
> +
> +    aio_set_fd_handler(client->aio_context,
> +                       nfs_get_fd(client->context),
> +                       NULL, NULL, NULL);
> +    client->events = 0;
> +}
> +
> +static void nfs_attach_aio_context(BlockDriverState *bs,
> +                                   AioContext *new_context)
> +{
> +    NFSClient *client = bs->opaque;
> +
> +    client->aio_context = new_context;
> +    nfs_set_events(client);
> +}
> +
> static void nfs_client_close(NFSClient *client)
> {
>     if (client->context) {
>         if (client->fh) {
>             nfs_close(client->context, client->fh);
>         }
> -        qemu_aio_set_fd_handler(nfs_get_fd(client->context), NULL, NULL,
> NULL);
> +        aio_set_fd_handler(client->aio_context,
> +                           nfs_get_fd(client->context),
> +                           NULL, NULL, NULL);
>         nfs_destroy_context(client->context);
>     }
>     memset(client, 0, sizeof(NFSClient));
> @@ -341,6 +366,8 @@ static int nfs_file_open(BlockDriverState *bs, QDict
> *options, int flags,
>     QemuOpts *opts;
>     Error *local_err = NULL;
> 
> +    client->aio_context = bdrv_get_aio_context(bs);
> +
>     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
>     qemu_opts_absorb_qdict(opts, options, &local_err);
>     if (local_err) {
> @@ -364,6 +391,8 @@ static int nfs_file_create(const char *url,
> QEMUOptionParameter *options,
>     int64_t total_size = 0;
>     NFSClient *client = g_malloc0(sizeof(NFSClient));
> 
> +    client->aio_context = qemu_get_aio_context();
> +
>     /* Read out options */
>     while (options && options->name) {
>         if (!strcmp(options->name, "size")) {
> @@ -403,7 +432,7 @@ static int64_t
> nfs_get_allocated_file_size(BlockDriverState *bs)
> 
>     while (!task.complete) {
>         nfs_set_events(client);
> -        qemu_aio_wait();
> +        aio_poll(bdrv_get_aio_context(bs), true);

Is the bdrv_get_aio_context(bs) call expensive?

Why not use client->aio_context instead of bdrv_get_aio_context(bs) here?

Peter

>     }
> 
>     return (task.ret < 0 ? task.ret : st.st_blocks * st.st_blksize);
> @@ -416,22 +445,25 @@ static int nfs_file_truncate(BlockDriverState *bs,
> int64_t offset)
> }
> 
> static BlockDriver bdrv_nfs = {
> -    .format_name     = "nfs",
> -    .protocol_name   = "nfs",
> -
> -    .instance_size   = sizeof(NFSClient),
> -    .bdrv_needs_filename = true,
> -    .bdrv_has_zero_init = nfs_has_zero_init,
> -    .bdrv_get_allocated_file_size = nfs_get_allocated_file_size,
> -    .bdrv_truncate = nfs_file_truncate,
> -
> -    .bdrv_file_open  = nfs_file_open,
> -    .bdrv_close      = nfs_file_close,
> -    .bdrv_create     = nfs_file_create,
> -
> -    .bdrv_co_readv         = nfs_co_readv,
> -    .bdrv_co_writev        = nfs_co_writev,
> -    .bdrv_co_flush_to_disk = nfs_co_flush,
> +    .format_name                    = "nfs",
> +    .protocol_name                  = "nfs",
> +
> +    .instance_size                  = sizeof(NFSClient),
> +    .bdrv_needs_filename            = true,
> +    .bdrv_has_zero_init             = nfs_has_zero_init,
> +    .bdrv_get_allocated_file_size   = nfs_get_allocated_file_size,
> +    .bdrv_truncate                  = nfs_file_truncate,
> +
> +    .bdrv_file_open                 = nfs_file_open,
> +    .bdrv_close                     = nfs_file_close,
> +    .bdrv_create                    = nfs_file_create,
> +
> +    .bdrv_co_readv                  = nfs_co_readv,
> +    .bdrv_co_writev                 = nfs_co_writev,
> +    .bdrv_co_flush_to_disk          = nfs_co_flush,
> +
> +    .bdrv_detach_aio_context        = nfs_detach_aio_context,
> +    .bdrv_attach_aio_context        = nfs_attach_aio_context,
> };
> 
> static void nfs_block_init(void)
> -- 
> 1.9.0
> 
> 
> 
> 
> 
>