Re: [PATCH 17/20] migration: remove the QEMUFileOps 'get_buffer' callback

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

* Daniel P. Berrangé (berrange@redhat.com) wrote:
> This directly implements the get_buffer logic using QIOChannel APIs.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  migration/qemu-file-channel.c | 29 -----------------------------
>  migration/qemu-file.c         | 18 ++++++++++++++++--
>  migration/qemu-file.h         |  9 ---------
>  3 files changed, 16 insertions(+), 40 deletions(-)
> 
> diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> index 8ff58e81f9..7b32831752 100644
> --- a/migration/qemu-file-channel.c
> +++ b/migration/qemu-file-channel.c
> @@ -74,34 +74,6 @@ static ssize_t channel_writev_buffer(void *opaque,
>  }
>  
>  
> -static ssize_t channel_get_buffer(void *opaque,
> -                                  uint8_t *buf,
> -                                  int64_t pos,
> -                                  size_t size,
> -                                  Error **errp)
> -{
> -    QIOChannel *ioc = QIO_CHANNEL(opaque);
> -    ssize_t ret;
> -
> -    do {
> -        ret = qio_channel_read(ioc, (char *)buf, size, errp);
> -        if (ret < 0) {
> -            if (ret == QIO_CHANNEL_ERR_BLOCK) {
> -                if (qemu_in_coroutine()) {
> -                    qio_channel_yield(ioc, G_IO_IN);
> -                } else {
> -                    qio_channel_wait(ioc, G_IO_IN);
> -                }
> -            } else {
> -                return -EIO;
> -            }
> -        }
> -    } while (ret == QIO_CHANNEL_ERR_BLOCK);
> -
> -    return ret;
> -}
> -
> -
>  static QEMUFile *channel_get_input_return_path(void *opaque)
>  {
>      QIOChannel *ioc = QIO_CHANNEL(opaque);
> @@ -117,7 +89,6 @@ static QEMUFile *channel_get_output_return_path(void *opaque)
>  }
>  
>  static const QEMUFileOps channel_input_ops = {
> -    .get_buffer = channel_get_buffer,
>      .get_return_path = channel_get_input_return_path,
>  };
>  
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index a855ce33dc..e024b43851 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -374,8 +374,22 @@ static ssize_t qemu_fill_buffer(QEMUFile *f)
>          return 0;
>      }
>  
> -    len = f->ops->get_buffer(f->ioc, f->buf + pending, f->total_transferred,
> -                             IO_BUF_SIZE - pending, &local_error);
> +    do {
> +        len = qio_channel_read(f->ioc,

Yes, I think that's OK - not that 'len' is an int where 'ret'
was a ssize_t; but I think our buffers are guranteed to be 'small'.


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

> +                               (char *)f->buf + pending,
> +                               IO_BUF_SIZE - pending,
> +                               &local_error);
> +        if (len == QIO_CHANNEL_ERR_BLOCK) {
> +            if (qemu_in_coroutine()) {
> +                qio_channel_yield(f->ioc, G_IO_IN);
> +            } else {
> +                qio_channel_wait(f->ioc, G_IO_IN);
> +            }
> +        } else if (len < 0) {
> +            len = EIO;
> +        }
> +    } while (len == QIO_CHANNEL_ERR_BLOCK);
> +
>      if (len > 0) {
>          f->buf_size += len;
>          f->total_transferred += len;
> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
> index 7ec105bf96..cd49184c00 100644
> --- a/migration/qemu-file.h
> +++ b/migration/qemu-file.h
> @@ -29,14 +29,6 @@
>  #include "exec/cpu-common.h"
>  #include "io/channel.h"
>  
> -/* Read a chunk of data from a file at the given position.  The pos argument
> - * can be ignored if the file is only be used for streaming.  The number of
> - * bytes actually read should be returned.
> - */
> -typedef ssize_t (QEMUFileGetBufferFunc)(void *opaque, uint8_t *buf,
> -                                        int64_t pos, size_t size,
> -                                        Error **errp);
> -
>  /*
>   * This function writes an iovec to file. The handler must write all
>   * of the data or return a negative errno value.
> @@ -77,7 +69,6 @@ typedef size_t (QEMURamSaveFunc)(QEMUFile *f,
>  typedef QEMUFile *(QEMURetPathFunc)(void *opaque);
>  
>  typedef struct QEMUFileOps {
> -    QEMUFileGetBufferFunc *get_buffer;
>      QEMUFileWritevBufferFunc *writev_buffer;
>      QEMURetPathFunc *get_return_path;
>  } QEMUFileOps;
> -- 
> 2.36.1
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK