From b88651cb4d4fa416fdbb6afaf5b26ec8c035eaad Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Fri, 13 May 2022 03:28:31 -0300 Subject: QIOChannel: Add flags on io_writev and introduce io_flush callback MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add flags to io_writev and introduce io_flush as optional callback to QIOChannelClass, allowing the implementation of zero copy writes by subclasses. How to use them: - Write data using qio_channel_writev*(...,QIO_CHANNEL_WRITE_FLAG_ZERO_COPY), - Wait write completion with qio_channel_flush(). Notes: As some zero copy write implementations work asynchronously, it's recommended to keep the write buffer untouched until the return of qio_channel_flush(), to avoid the risk of sending an updated buffer instead of the buffer state during write. As io_flush callback is optional, if a subclass does not implement it, then: - io_flush will return 0 without changing anything. Also, some functions like qio_channel_writev_full_all() were adapted to receive a flag parameter. That allows shared code between zero copy and non-zero copy writev, and also an easier implementation on new flags. Signed-off-by: Leonardo Bras Reviewed-by: Daniel P. Berrangé Reviewed-by: Peter Xu Reviewed-by: Juan Quintela Message-Id: <20220513062836.965425-3-leobras@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- io/channel-buffer.c | 1 + io/channel-command.c | 1 + io/channel-file.c | 1 + io/channel-socket.c | 2 ++ io/channel-tls.c | 1 + io/channel-websock.c | 1 + io/channel.c | 49 +++++++++++++++++++++++++++++++++++++++---------- 7 files changed, 46 insertions(+), 10 deletions(-) (limited to 'io') diff --git a/io/channel-buffer.c b/io/channel-buffer.c index baa4e2b..bf52011 100644 --- a/io/channel-buffer.c +++ b/io/channel-buffer.c @@ -81,6 +81,7 @@ static ssize_t qio_channel_buffer_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelBuffer *bioc = QIO_CHANNEL_BUFFER(ioc); diff --git a/io/channel-command.c b/io/channel-command.c index 4a1f969..9f2f4a1 100644 --- a/io/channel-command.c +++ b/io/channel-command.c @@ -276,6 +276,7 @@ static ssize_t qio_channel_command_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc); diff --git a/io/channel-file.c b/io/channel-file.c index d146ace..b67687c 100644 --- a/io/channel-file.c +++ b/io/channel-file.c @@ -114,6 +114,7 @@ static ssize_t qio_channel_file_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc); diff --git a/io/channel-socket.c b/io/channel-socket.c index e531d7b..05c425a 100644 --- a/io/channel-socket.c +++ b/io/channel-socket.c @@ -524,6 +524,7 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc); @@ -619,6 +620,7 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc); diff --git a/io/channel-tls.c b/io/channel-tls.c index 2ae1b92..4ce890a 100644 --- a/io/channel-tls.c +++ b/io/channel-tls.c @@ -301,6 +301,7 @@ static ssize_t qio_channel_tls_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc); diff --git a/io/channel-websock.c b/io/channel-websock.c index 55145a6..9619906 100644 --- a/io/channel-websock.c +++ b/io/channel-websock.c @@ -1127,6 +1127,7 @@ static ssize_t qio_channel_websock_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelWebsock *wioc = QIO_CHANNEL_WEBSOCK(ioc); diff --git a/io/channel.c b/io/channel.c index e8b019d..0640941 100644 --- a/io/channel.c +++ b/io/channel.c @@ -72,18 +72,32 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc); - if ((fds || nfds) && - !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) { + if (fds || nfds) { + if (!qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) { + error_setg_errno(errp, EINVAL, + "Channel does not support file descriptor passing"); + return -1; + } + if (flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) { + error_setg_errno(errp, EINVAL, + "Zero Copy does not support file descriptor passing"); + return -1; + } + } + + if ((flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) && + !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) { error_setg_errno(errp, EINVAL, - "Channel does not support file descriptor passing"); + "Requested Zero Copy feature is not available"); return -1; } - return klass->io_writev(ioc, iov, niov, fds, nfds, errp); + return klass->io_writev(ioc, iov, niov, fds, nfds, flags, errp); } @@ -217,14 +231,14 @@ int qio_channel_writev_all(QIOChannel *ioc, size_t niov, Error **errp) { - return qio_channel_writev_full_all(ioc, iov, niov, NULL, 0, errp); + return qio_channel_writev_full_all(ioc, iov, niov, NULL, 0, 0, errp); } int qio_channel_writev_full_all(QIOChannel *ioc, const struct iovec *iov, size_t niov, int *fds, size_t nfds, - Error **errp) + int flags, Error **errp) { int ret = -1; struct iovec *local_iov = g_new(struct iovec, niov); @@ -237,8 +251,10 @@ int qio_channel_writev_full_all(QIOChannel *ioc, while (nlocal_iov > 0) { ssize_t len; - len = qio_channel_writev_full(ioc, local_iov, nlocal_iov, fds, nfds, - errp); + + len = qio_channel_writev_full(ioc, local_iov, nlocal_iov, fds, + nfds, flags, errp); + if (len == QIO_CHANNEL_ERR_BLOCK) { if (qemu_in_coroutine()) { qio_channel_yield(ioc, G_IO_OUT); @@ -277,7 +293,7 @@ ssize_t qio_channel_writev(QIOChannel *ioc, size_t niov, Error **errp) { - return qio_channel_writev_full(ioc, iov, niov, NULL, 0, errp); + return qio_channel_writev_full(ioc, iov, niov, NULL, 0, 0, errp); } @@ -297,7 +313,7 @@ ssize_t qio_channel_write(QIOChannel *ioc, Error **errp) { struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen }; - return qio_channel_writev_full(ioc, &iov, 1, NULL, 0, errp); + return qio_channel_writev_full(ioc, &iov, 1, NULL, 0, 0, errp); } @@ -473,6 +489,19 @@ off_t qio_channel_io_seek(QIOChannel *ioc, return klass->io_seek(ioc, offset, whence, errp); } +int qio_channel_flush(QIOChannel *ioc, + Error **errp) +{ + QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc); + + if (!klass->io_flush || + !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY)) { + return 0; + } + + return klass->io_flush(ioc, errp); +} + static void qio_channel_restart_read(void *opaque) { -- cgit v1.1