Commit caad5384 authored by Vladimir Sementsov-Ogievskiy's avatar Vladimir Sementsov-Ogievskiy Committed by Eric Blake
Browse files

nbd/server: structurize simple reply header sending 



Use packed structure instead of pointer arithmetics.

Also, merge two redundant traces into one.

Signed-off-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20171012095319.136610-5-vsementsov@virtuozzo.com>
[eblake: tweak and mention impact on traces, fix errp usage]
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent 7b3158f9

include/block/nbd.h

+6 −0
Original line number Diff line number Diff line
@@ -63,6 +63,12 @@ struct NBDReply { 
};

typedef struct NBDReply NBDReply;



typedef struct NBDSimpleReply {

    uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */

    uint32_t error;

    uint64_t handle;

} QEMU_PACKED NBDSimpleReply;



/* Transmission (export) flags: sent from server to client during handshake,

   but describe what will happen during transmission */

#define NBD_FLAG_HAS_FLAGS      (1 << 0)        /* Flags are there */

nbd/server.c

+14 −23
Original line number Diff line number Diff line
@@ -902,26 +902,6 @@ static int nbd_receive_request(QIOChannel *ioc, NBDRequest *request, 
    return 0;

}



static int nbd_send_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)

{

    uint8_t buf[NBD_REPLY_SIZE];



    reply->error = system_errno_to_nbd_errno(reply->error);



    trace_nbd_send_reply(reply->error, reply->handle);



    /* Reply

       [ 0 ..  3]    magic   (NBD_SIMPLE_REPLY_MAGIC)

       [ 4 ..  7]    error   (0 == no error)

       [ 7 .. 15]    handle

     */

    stl_be_p(buf, NBD_SIMPLE_REPLY_MAGIC);

    stl_be_p(buf + 4, reply->error);

    stq_be_p(buf + 8, reply->handle);



    return nbd_write(ioc, buf, sizeof(buf), errp);

}



#define MAX_NBD_REQUESTS 16



void nbd_client_get(NBDClient *client)
@@ -1208,24 +1188,35 @@ void nbd_export_close_all(void) 
    }

}



static inline void set_be_simple_reply(NBDSimpleReply *reply, uint64_t error,

                                       uint64_t handle)

{

    stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC);

    stl_be_p(&reply->error, error);

    stq_be_p(&reply->handle, handle);

}



static int nbd_co_send_simple_reply(NBDRequestData *req, NBDReply *reply,

                                    int len, Error **errp)

{

    NBDClient *client = req->client;

    NBDSimpleReply simple_reply;

    int nbd_err = system_errno_to_nbd_errno(reply->error);

    int ret;



    g_assert(qemu_in_coroutine());



    trace_nbd_co_send_simple_reply(reply->handle, reply->error, len);

    trace_nbd_co_send_simple_reply(reply->handle, nbd_err, len);

    set_be_simple_reply(&simple_reply, nbd_err, reply->handle);



    qemu_co_mutex_lock(&client->send_lock);

    client->send_coroutine = qemu_coroutine_self();



    if (!len) {

        ret = nbd_send_reply(client->ioc, reply, errp);

        ret = nbd_write(client->ioc, &simple_reply, sizeof(simple_reply), errp);

    } else {

        qio_channel_set_cork(client->ioc, true);

        ret = nbd_send_reply(client->ioc, reply, errp);

        ret = nbd_write(client->ioc, &simple_reply, sizeof(simple_reply), errp);

        if (ret == 0) {

            ret = nbd_write(client->ioc, req->data, len, errp);

            if (ret < 0) {

nbd/trace-events

+0 −1
Original line number Diff line number Diff line
@@ -51,7 +51,6 @@ nbd_negotiate_old_style(uint64_t size, unsigned flags) "advertising size %" PRIu 
nbd_negotiate_new_style_size_flags(uint64_t size, unsigned flags) "advertising size %" PRIu64 " and flags 0x%x"

nbd_negotiate_success(void) "Negotiation succeeded"

nbd_receive_request(uint32_t magic, uint16_t flags, uint16_t type, uint64_t from, uint32_t len) "Got request: { magic = 0x%" PRIx32 ", .flags = 0x%" PRIx16 ", .type = 0x%" PRIx16 ", from = %" PRIu64 ", len = %" PRIu32 " }"

nbd_send_reply(int32_t error, uint64_t handle) "Sending response to client: { .error = %" PRId32 ", handle = %" PRIu64 " }"

nbd_blk_aio_attached(const char *name, void *ctx) "Export %s: Attaching clients to AIO context %p\n"

nbd_blk_aio_detach(const char *name, void *ctx) "Export %s: Detaching clients from AIO context %p\n"

nbd_co_send_simple_reply(uint64_t handle, uint32_t error, int len) "Send simple reply: handle = %" PRIu64 ", error = %" PRIu32 ", len = %d"