Re: [PATCH 18/20] migration: remove the QEMUFileOps 'writev_buffer' callback

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Daniel P. Berrangé (berrange@redhat.com) wrote:
> This directly implements the writev_buffer logic using QIOChannel APIs.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  migration/qemu-file-channel.c | 43 -----------------------------------
>  migration/qemu-file.c         | 24 +++++++------------
>  migration/qemu-file.h         |  9 --------
>  3 files changed, 8 insertions(+), 68 deletions(-)
> 
> diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> index 7b32831752..2e139f7bcd 100644
> --- a/migration/qemu-file-channel.c
> +++ b/migration/qemu-file-channel.c
> @@ -32,48 +32,6 @@
>  #include "yank_functions.h"
>  
>  
> -static ssize_t channel_writev_buffer(void *opaque,
> -                                     struct iovec *iov,
> -                                     int iovcnt,
> -                                     int64_t pos,
> -                                     Error **errp)
> -{
> -    QIOChannel *ioc = QIO_CHANNEL(opaque);
> -    ssize_t done = 0;
> -    struct iovec *local_iov = g_new(struct iovec, iovcnt);
> -    struct iovec *local_iov_head = local_iov;
> -    unsigned int nlocal_iov = iovcnt;
> -
> -    nlocal_iov = iov_copy(local_iov, nlocal_iov,
> -                          iov, iovcnt,
> -                          0, iov_size(iov, iovcnt));
> -
> -    while (nlocal_iov > 0) {
> -        ssize_t len;
> -        len = qio_channel_writev(ioc, local_iov, nlocal_iov, errp);
> -        if (len == QIO_CHANNEL_ERR_BLOCK) {
> -            if (qemu_in_coroutine()) {
> -                qio_channel_yield(ioc, G_IO_OUT);
> -            } else {
> -                qio_channel_wait(ioc, G_IO_OUT);
> -            }
> -            continue;

I wondered where that code went, but it turns out it's already copied
into qio_channel_writev_full_all, so:


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> -        }
> -        if (len < 0) {
> -            done = -EIO;
> -            goto cleanup;
> -        }
> -
> -        iov_discard_front(&local_iov, &nlocal_iov, len);
> -        done += len;
> -    }
> -
> - cleanup:
> -    g_free(local_iov_head);
> -    return done;
> -}
> -
> -
>  static QEMUFile *channel_get_input_return_path(void *opaque)
>  {
>      QIOChannel *ioc = QIO_CHANNEL(opaque);
> @@ -94,7 +52,6 @@ static const QEMUFileOps channel_input_ops = {
>  
>  
>  static const QEMUFileOps channel_output_ops = {
> -    .writev_buffer = channel_writev_buffer,
>      .get_return_path = channel_get_output_return_path,
>  };
>  
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index e024b43851..72a6f58af5 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -245,10 +245,6 @@ static void qemu_iovec_release_ram(QEMUFile *f)
>   */
>  void qemu_fflush(QEMUFile *f)
>  {
> -    ssize_t ret = 0;
> -    ssize_t expect = 0;
> -    Error *local_error = NULL;
> -
>      if (!qemu_file_is_writable(f)) {
>          return;
>      }
> @@ -257,22 +253,18 @@ void qemu_fflush(QEMUFile *f)
>          return;
>      }
>      if (f->iovcnt > 0) {
> -        expect = iov_size(f->iov, f->iovcnt);
> -        ret = f->ops->writev_buffer(f->ioc, f->iov, f->iovcnt, f->total_transferred,
> -                                    &local_error);
> +        Error *local_error = NULL;
> +        if (qio_channel_writev_all(f->ioc,
> +                                   f->iov, f->iovcnt,
> +                                   &local_error) < 0) {
> +            qemu_file_set_error_obj(f, -EIO, local_error);
> +        } else {
> +            f->total_transferred += iov_size(f->iov, f->iovcnt);
> +        }
>  
>          qemu_iovec_release_ram(f);
>      }
>  
> -    if (ret >= 0) {
> -        f->total_transferred += ret;
> -    }
> -    /* We expect the QEMUFile write impl to send the full
> -     * data set we requested, so sanity check that.
> -     */
> -    if (ret != expect) {
> -        qemu_file_set_error_obj(f, ret < 0 ? ret : -EIO, local_error);
> -    }
>      f->buf_index = 0;
>      f->iovcnt = 0;
>  }
> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
> index cd49184c00..542c637934 100644
> --- a/migration/qemu-file.h
> +++ b/migration/qemu-file.h
> @@ -29,14 +29,6 @@
>  #include "exec/cpu-common.h"
>  #include "io/channel.h"
>  
> -/*
> - * This function writes an iovec to file. The handler must write all
> - * of the data or return a negative errno value.
> - */
> -typedef ssize_t (QEMUFileWritevBufferFunc)(void *opaque, struct iovec *iov,
> -                                           int iovcnt, int64_t pos,
> -                                           Error **errp);
> -
>  /*
>   * This function provides hooks around different
>   * stages of RAM migration.
> @@ -69,7 +61,6 @@ typedef size_t (QEMURamSaveFunc)(QEMUFile *f,
>  typedef QEMUFile *(QEMURetPathFunc)(void *opaque);
>  
>  typedef struct QEMUFileOps {
> -    QEMUFileWritevBufferFunc *writev_buffer;
>      QEMURetPathFunc *get_return_path;
>  } QEMUFileOps;
>  
> -- 
> 2.36.1
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK