Re: [Qemu-devel] [PATCH 3/3] nbd: Use new qio_channel_*_all() functions

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Sep 05, 2017 at 02:11:14PM -0500, Eric Blake wrote:
> Rather than open-coding our own read/write-all functions, we
> can make use of the recently-added qio code.  It slightly
> changes the error message in one of the iotests.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  include/block/nbd.h        |  2 --
>  nbd/nbd-internal.h         | 41 +++++++----------------------------------
>  block/nbd-client.c         | 15 +++++++--------
>  nbd/common.c               | 45 ---------------------------------------------
>  tests/qemu-iotests/083.out |  8 ++++----
>  5 files changed, 18 insertions(+), 93 deletions(-)
> 
> diff --git a/include/block/nbd.h b/include/block/nbd.h
> index 040cdd2e60..707fd37575 100644
> --- a/include/block/nbd.h
> +++ b/include/block/nbd.h
> @@ -155,8 +155,6 @@ struct NBDExportInfo {
>  };
>  typedef struct NBDExportInfo NBDExportInfo;
> 
> -ssize_t nbd_rwv(QIOChannel *ioc, struct iovec *iov, size_t niov, size_t length,
> -                bool do_read, Error **errp);
>  int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
>                            QCryptoTLSCreds *tlscreds, const char *hostname,
>                            QIOChannel **outioc, NBDExportInfo *info,
> diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
> index 03549e3f39..8a609a227f 100644
> --- a/nbd/nbd-internal.h
> +++ b/nbd/nbd-internal.h
> @@ -85,28 +85,14 @@
>  static inline int nbd_read_eof(QIOChannel *ioc, void *buffer, size_t size,
>                                 Error **errp)
>  {
> -    struct iovec iov = { .iov_base = buffer, .iov_len = size };
> -    ssize_t ret;
> -
> -    /* Sockets are kept in blocking mode in the negotiation phase.  After
> -     * that, a non-readable socket simply means that another thread stole
> -     * our request/reply.  Synchronization is done with recv_coroutine, so
> -     * that this is coroutine-safe.
> -     */
> +    int ret;
> 
>      assert(size);
> -
> -    ret = nbd_rwv(ioc, &iov, 1, size, true, errp);
> -    if (ret <= 0) {
> -        return ret;
> +    ret = qio_channel_read_all_eof(ioc, buffer, size, errp);
> +    if (ret < 0) {
> +        ret = -EIO;
>      }
> -
> -    if (ret != size) {
> -        error_setg(errp, "End of file");
> -        return -EINVAL;
> -    }
> -
> -    return 1;
> +    return ret;
>  }
> 
>  /* nbd_read
> @@ -115,14 +101,7 @@ static inline int nbd_read_eof(QIOChannel *ioc, void *buffer, size_t size,
>  static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
>                             Error **errp)
>  {
> -    int ret = nbd_read_eof(ioc, buffer, size, errp);
> -
> -    if (ret == 0) {
> -        ret = -EINVAL;
> -        error_setg(errp, "End of file");
> -    }
> -
> -    return ret < 0 ? ret : 0;
> +    return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
>  }
> 
>  /* nbd_write
> @@ -131,13 +110,7 @@ static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
>  static inline int nbd_write(QIOChannel *ioc, const void *buffer, size_t size,
>                              Error **errp)
>  {
> -    struct iovec iov = { .iov_base = (void *) buffer, .iov_len = size };
> -
> -    ssize_t ret = nbd_rwv(ioc, &iov, 1, size, false, errp);
> -
> -    assert(ret < 0 || ret == size);
> -
> -    return ret < 0 ? ret : 0;
> +    return qio_channel_write_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
>  }
> 
>  struct NBDTLSHandshakeData {
> diff --git a/block/nbd-client.c b/block/nbd-client.c
> index f0dbea24d3..ee7f758e68 100644
> --- a/block/nbd-client.c
> +++ b/block/nbd-client.c
> @@ -121,7 +121,7 @@ static int nbd_co_send_request(BlockDriverState *bs,
>                                 QEMUIOVector *qiov)
>  {
>      NBDClientSession *s = nbd_get_client_session(bs);
> -    int rc, ret, i;
> +    int rc, i;
> 
>      qemu_co_mutex_lock(&s->send_mutex);
>      while (s->in_flight == MAX_NBD_REQUESTS) {
> @@ -156,9 +156,9 @@ static int nbd_co_send_request(BlockDriverState *bs,
>          qio_channel_set_cork(s->ioc, true);
>          rc = nbd_send_request(s->ioc, request);
>          if (rc >= 0 && !s->quit) {
> -            ret = nbd_rwv(s->ioc, qiov->iov, qiov->niov, request->len, false,
> -                          NULL);
> -            if (ret != request->len) {
> +            assert(request->len == iov_size(qiov->iov, qiov->niov));
> +            if (qio_channel_writev_all(s->ioc, qiov->iov, qiov->niov,
> +                                       NULL) < 0) {
>                  rc = -EIO;
>              }
>          }
> @@ -184,7 +184,6 @@ static void nbd_co_receive_reply(NBDClientSession *s,
>                                   QEMUIOVector *qiov)
>  {
>      int i = HANDLE_TO_INDEX(s, request->handle);
> -    int ret;
> 
>      /* Wait until we're woken up by nbd_read_reply_entry.  */
>      s->requests[i].receiving = true;
> @@ -195,9 +194,9 @@ static void nbd_co_receive_reply(NBDClientSession *s,
>          reply->error = EIO;
>      } else {
>          if (qiov && reply->error == 0) {
> -            ret = nbd_rwv(s->ioc, qiov->iov, qiov->niov, request->len, true,
> -                          NULL);
> -            if (ret != request->len) {
> +            assert(request->len == iov_size(qiov->iov, qiov->niov));
> +            if (qio_channel_readv_all(s->ioc, qiov->iov, qiov->niov,
> +                                      NULL) < 0) {
>                  reply->error = EIO;
>                  s->quit = true;
>              }
> diff --git a/nbd/common.c b/nbd/common.c
> index e288d1b972..59a5316be9 100644
> --- a/nbd/common.c
> +++ b/nbd/common.c
> @@ -20,51 +20,6 @@
>  #include "qapi/error.h"
>  #include "nbd-internal.h"
> 
> -/* nbd_wr_syncv
> - * The function may be called from coroutine or from non-coroutine context.
> - * When called from non-coroutine context @ioc must be in blocking mode.
> - */
> -ssize_t nbd_rwv(QIOChannel *ioc, struct iovec *iov, size_t niov, size_t length,
> -                bool do_read, Error **errp)
> -{
> -    ssize_t done = 0;
> -    struct iovec *local_iov = g_new(struct iovec, niov);
> -    struct iovec *local_iov_head = local_iov;
> -    unsigned int nlocal_iov = niov;
> -
> -    nlocal_iov = iov_copy(local_iov, nlocal_iov, iov, niov, 0, length);
> -
> -    while (nlocal_iov > 0) {
> -        ssize_t len;
> -        if (do_read) {
> -            len = qio_channel_readv(ioc, local_iov, nlocal_iov, errp);
> -        } else {
> -            len = qio_channel_writev(ioc, local_iov, nlocal_iov, errp);
> -        }
> -        if (len == QIO_CHANNEL_ERR_BLOCK) {
> -            /* errp should not be set */
> -            assert(qemu_in_coroutine());
> -            qio_channel_yield(ioc, do_read ? G_IO_IN : G_IO_OUT);
> -            continue;
> -        }
> -        if (len < 0) {
> -            done = -EIO;
> -            goto cleanup;
> -        }
> -
> -        if (do_read && len == 0) {
> -            break;
> -        }
> -
> -        iov_discard_front(&local_iov, &nlocal_iov, len);
> -        done += len;
> -    }
> -
> - cleanup:
> -    g_free(local_iov_head);
> -    return done;
> -}
> -
>  /* Discard length bytes from channel.  Return -errno on failure and 0 on
>   * success */
>  int nbd_drop(QIOChannel *ioc, size_t size, Error **errp)
> diff --git a/tests/qemu-iotests/083.out b/tests/qemu-iotests/083.out
> index fb71b6f8ad..25dde519e3 100644
> --- a/tests/qemu-iotests/083.out
> +++ b/tests/qemu-iotests/083.out
> @@ -69,12 +69,12 @@ read failed: Input/output error
> 
>  === Check disconnect 4 reply ===
> 
> -End of file
> +Unexpected end-of-file before all bytes were read
>  read failed: Input/output error
> 
>  === Check disconnect 8 reply ===
> 
> -End of file
> +Unexpected end-of-file before all bytes were read
>  read failed: Input/output error
> 
>  === Check disconnect before data ===
> @@ -180,12 +180,12 @@ read failed: Input/output error
> 
>  === Check disconnect 4 reply ===
> 
> -End of file
> +Unexpected end-of-file before all bytes were read
>  read failed: Input/output error
> 
>  === Check disconnect 8 reply ===
> 
> -End of file
> +Unexpected end-of-file before all bytes were read
>  read failed: Input/output error
> 
>  === Check disconnect before data ===

Reviewed-by: Daniel P. Berrange <berrange@redhat.com>

Regards,
Daniel
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