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 <leob...@redhat.com> Reviewed-by: Daniel P. Berrangé <berra...@redhat.com> Reviewed-by: Peter Xu <pet...@redhat.com> Reviewed-by: Juan Quintela <quint...@redhat.com> --- include/io/channel.h | 38 +++++++++++++++++++++- chardev/char-io.c | 2 +- hw/remote/mpqemu-link.c | 2 +- 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 +++++++++++++++++++++++------ migration/rdma.c | 1 + scsi/pr-manager-helper.c | 2 +- tests/unit/test-io-channel-socket.c | 1 + 13 files changed, 88 insertions(+), 14 deletions(-) diff --git a/include/io/channel.h b/include/io/channel.h index 88988979f8..c680ee7480 100644 --- a/include/io/channel.h +++ b/include/io/channel.h @@ -32,12 +32,15 @@ OBJECT_DECLARE_TYPE(QIOChannel, QIOChannelClass, #define QIO_CHANNEL_ERR_BLOCK -2 +#define QIO_CHANNEL_WRITE_FLAG_ZERO_COPY 0x1 + typedef enum QIOChannelFeature QIOChannelFeature; enum QIOChannelFeature { QIO_CHANNEL_FEATURE_FD_PASS, QIO_CHANNEL_FEATURE_SHUTDOWN, QIO_CHANNEL_FEATURE_LISTEN, + QIO_CHANNEL_FEATURE_WRITE_ZERO_COPY, }; @@ -104,6 +107,7 @@ struct QIOChannelClass { size_t niov, int *fds, size_t nfds, + int flags, Error **errp); ssize_t (*io_readv)(QIOChannel *ioc, const struct iovec *iov, @@ -136,6 +140,8 @@ struct QIOChannelClass { IOHandler *io_read, IOHandler *io_write, void *opaque); + int (*io_flush)(QIOChannel *ioc, + Error **errp); }; /* General I/O handling functions */ @@ -228,6 +234,7 @@ ssize_t qio_channel_readv_full(QIOChannel *ioc, * @niov: the length of the @iov array * @fds: an array of file handles to send * @nfds: number of file handles in @fds + * @flags: write flags (QIO_CHANNEL_WRITE_FLAG_*) * @errp: pointer to a NULL-initialized error object * * Write data to the IO channel, reading it from the @@ -260,6 +267,7 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp); /** @@ -837,6 +845,7 @@ int qio_channel_readv_full_all(QIOChannel *ioc, * @niov: the length of the @iov array * @fds: an array of file handles to send * @nfds: number of file handles in @fds + * @flags: write flags (QIO_CHANNEL_WRITE_FLAG_*) * @errp: pointer to a NULL-initialized error object * * @@ -846,6 +855,14 @@ int qio_channel_readv_full_all(QIOChannel *ioc, * to be written, yielding from the current coroutine * if required. * + * If QIO_CHANNEL_WRITE_FLAG_ZERO_COPY is passed in flags, + * instead of waiting for all requested data to be written, + * this function will wait until it's all queued for writing. + * In this case, if the buffer gets changed between queueing and + * sending, the updated buffer will be sent. If this is not a + * desired behavior, it's suggested to call qio_channel_flush() + * before reusing the buffer. + * * Returns: 0 if all bytes were written, or -1 on error */ @@ -853,6 +870,25 @@ 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); + +/** + * qio_channel_flush: + * @ioc: the channel object + * @errp: pointer to a NULL-initialized error object + * + * Will block until every packet queued with + * qio_channel_writev_full() + QIO_CHANNEL_WRITE_FLAG_ZERO_COPY + * is sent, or return in case of any error. + * + * If not implemented, acts as a no-op, and returns 0. + * + * Returns -1 if any error is found, + * 1 if every send failed to use zero copy. + * 0 otherwise. + */ + +int qio_channel_flush(QIOChannel *ioc, + Error **errp); #endif /* QIO_CHANNEL_H */ diff --git a/chardev/char-io.c b/chardev/char-io.c index 8ced184160..4451128cba 100644 --- a/chardev/char-io.c +++ b/chardev/char-io.c @@ -122,7 +122,7 @@ int io_channel_send_full(QIOChannel *ioc, ret = qio_channel_writev_full( ioc, &iov, 1, - fds, nfds, NULL); + fds, nfds, 0, NULL); if (ret == QIO_CHANNEL_ERR_BLOCK) { if (offset) { return offset; diff --git a/hw/remote/mpqemu-link.c b/hw/remote/mpqemu-link.c index 2a4aa651ca..9bd98e8219 100644 --- a/hw/remote/mpqemu-link.c +++ b/hw/remote/mpqemu-link.c @@ -68,7 +68,7 @@ bool mpqemu_msg_send(MPQemuMsg *msg, QIOChannel *ioc, Error **errp) } if (!qio_channel_writev_full_all(ioc, send, G_N_ELEMENTS(send), - fds, nfds, errp)) { + fds, nfds, 0, errp)) { ret = true; } else { trace_mpqemu_send_io_error(msg->cmd, msg->size, nfds); diff --git a/io/channel-buffer.c b/io/channel-buffer.c index baa4e2b089..bf52011be2 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 4a1f969aaa..9f2f4a1793 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 d146ace7db..b67687c2aa 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 e531d7bd2a..05c425abb8 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 2ae1b92fc0..4ce890a538 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 55145a6a8c..9619906ac3 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 e8b019dc36..0640941ac5 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) { diff --git a/migration/rdma.c b/migration/rdma.c index ef1e65ec36..672d1958a9 100644 --- a/migration/rdma.c +++ b/migration/rdma.c @@ -2840,6 +2840,7 @@ static ssize_t qio_channel_rdma_writev(QIOChannel *ioc, size_t niov, int *fds, size_t nfds, + int flags, Error **errp) { QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc); diff --git a/scsi/pr-manager-helper.c b/scsi/pr-manager-helper.c index 451c7631b7..3be52a98d5 100644 --- a/scsi/pr-manager-helper.c +++ b/scsi/pr-manager-helper.c @@ -77,7 +77,7 @@ static int pr_manager_helper_write(PRManagerHelper *pr_mgr, iov.iov_base = (void *)buf; iov.iov_len = sz; n_written = qio_channel_writev_full(QIO_CHANNEL(pr_mgr->ioc), &iov, 1, - nfds ? &fd : NULL, nfds, errp); + nfds ? &fd : NULL, nfds, 0, errp); if (n_written <= 0) { assert(n_written != QIO_CHANNEL_ERR_BLOCK); diff --git a/tests/unit/test-io-channel-socket.c b/tests/unit/test-io-channel-socket.c index c49eec1f03..6713886d02 100644 --- a/tests/unit/test-io-channel-socket.c +++ b/tests/unit/test-io-channel-socket.c @@ -444,6 +444,7 @@ static void test_io_channel_unix_fd_pass(void) G_N_ELEMENTS(iosend), fdsend, G_N_ELEMENTS(fdsend), + 0, &error_abort); qio_channel_readv_full(dst, -- 2.36.0