Re: [PATCH v3 2/4] io/channel: introduce qio_channel_pwrite{v, }_all()

[Fabiano Rosas <farosas@suse.de>]

Junjie Cao <junjie.cao@intel.com> writes:

> Add positioned write helpers that retry on short writes, matching
> the pread_all family from the previous patch.
>
>   qio_channel_pwritev_all()  -- retry loop; returns 0 on success,
>                                  -1 on error.
>   qio_channel_pwrite_all()   -- single-buffer convenience wrapper.
>
> Signed-off-by: Junjie Cao <junjie.cao@intel.com>
> ---
>  include/io/channel.h | 41 +++++++++++++++++++++++++++++++++++++
>  io/channel.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 89 insertions(+)
>
> diff --git a/include/io/channel.h b/include/io/channel.h
> index 47af409ede..287d10cd6f 100644
> --- a/include/io/channel.h
> +++ b/include/io/channel.h
> @@ -598,6 +598,47 @@ ssize_t qio_channel_pwritev(QIOChannel *ioc, const struct iovec *iov,
>  ssize_t qio_channel_pwrite(QIOChannel *ioc, void *buf, size_t buflen,
>                             off_t offset, Error **errp);
>  
> +/**
> + * qio_channel_pwritev_all:
> + * @ioc: the channel object
> + * @iov: the array of memory regions to write data from
> + * @niov: the length of the @iov array
> + * @offset: the starting offset in the channel to write to
> + * @errp: pointer to a NULL-initialized error object
> + *
> + * Writes @iov, possibly blocking or (if the channel is non-blocking)
> + * yielding from the current coroutine multiple times until the entire
> + * content is written.  Otherwise behaves as qio_channel_pwritev().
> + *
> + * Returns: 0 if all bytes were written, or -1 on error
> + */
> +int coroutine_mixed_fn qio_channel_pwritev_all(QIOChannel *ioc,
> +                                               const struct iovec *iov,
> +                                               size_t niov,
> +                                               off_t offset,
> +                                               Error **errp);
> +
> +/**
> + * qio_channel_pwrite_all:
> + * @ioc: the channel object
> + * @buf: the memory region to write data from
> + * @buflen: the number of bytes to write from @buf
> + * @offset: the starting offset in the channel to write to
> + * @errp: pointer to a NULL-initialized error object
> + *
> + * Writes @buflen bytes from @buf, possibly blocking or (if the
> + * channel is non-blocking) yielding from the current coroutine
> + * multiple times until the entire content is written.  Otherwise
> + * behaves as qio_channel_pwrite().
> + *
> + * Returns: 0 if all bytes were written, or -1 on error
> + */
> +int coroutine_mixed_fn qio_channel_pwrite_all(QIOChannel *ioc,
> +                                              const void *buf,
> +                                              size_t buflen,
> +                                              off_t offset,
> +                                              Error **errp);
> +
>  /**
>   * qio_channel_preadv
>   * @ioc: the channel object
> diff --git a/io/channel.c b/io/channel.c
> index 52c1abfcbc..2853dadb68 100644
> --- a/io/channel.c
> +++ b/io/channel.c
> @@ -478,6 +478,54 @@ ssize_t qio_channel_pwrite(QIOChannel *ioc, void *buf, size_t buflen,
>      return qio_channel_pwritev(ioc, &iov, 1, offset, errp);
>  }
>  
> +int coroutine_mixed_fn qio_channel_pwritev_all(QIOChannel *ioc,
> +                                               const struct iovec *iov,
> +                                               size_t niov,
> +                                               off_t offset,
> +                                               Error **errp)
> +{
> +    int ret = -1;
> +    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, iov_size(iov, niov));
> +
> +    while (nlocal_iov > 0) {
> +        ssize_t len;
> +
> +        len = qio_channel_pwritev(ioc, local_iov, nlocal_iov, offset, errp);
> +
> +        if (len == QIO_CHANNEL_ERR_BLOCK) {
> +            qio_channel_wait_cond(ioc, G_IO_OUT);
> +            continue;
> +        }
> +        if (len < 0) {
> +            goto cleanup;
> +        }
> +
> +        offset += len;
> +        iov_discard_front(&local_iov, &nlocal_iov, len);
> +    }
> +
> +    ret = 0;
> + cleanup:
> +    g_free(local_iov_head);
> +    return ret;
> +}
> +
> +int coroutine_mixed_fn qio_channel_pwrite_all(QIOChannel *ioc,
> +                                              const void *buf,
> +                                              size_t buflen,
> +                                              off_t offset,
> +                                              Error **errp)
> +{
> +    struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
> +    return qio_channel_pwritev_all(ioc, &iov, 1, offset, errp);
> +}
> +
>  ssize_t qio_channel_preadv(QIOChannel *ioc, const struct iovec *iov,
>                             size_t niov, off_t offset, Error **errp)
>  {

Reviewed-by: Fabiano Rosas <farosas@suse.de>