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From 24a9e4d46608ccdcec53eeccc40b7a5d3fb7c9c8 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Fri, 16 Jan 2015 17:35:36 +0100
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Subject: [PATCH 04/16] Handle bi-directional communication for fd migration
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Message-id: <1421429737-23581-3-git-send-email-dgilbert@redhat.com>
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Patchwork-id: 63333
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O-Subject: [RHEL-7.2 qemu-kvm PATCH 2/3] Handle bi-directional communication for fd migration
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Bugzilla: 1086168
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Amit Shah <amit.shah@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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From: Cristian Klein <cristian.klein@cs.umu.se>
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libvirt prefers opening the TCP connection itself, for two reasons.
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First, connection failed errors can be detected easier, without having
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to parse qemu's error output.
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Second, libvirt might be asked to secure the transfer by tunnelling the
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communication through an TLS layer.
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Therefore, libvirt opens the TCP connection itself and passes an FD to qemu
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using QMP and a POSIX-specific mechanism.
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Hence, in order to make the reverse-path work in such cases, qemu needs to
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distinguish if the transmitted FD is a socket (reverse-path available)
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or not (reverse-path might not be available) and use the corresponding
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abstraction.
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Signed-off-by: Cristian Klein <cristian.klein@cs.umu.se>
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Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
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Reviewed-by: Amit Shah <amit.shah@redhat.com>
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Signed-off-by: Amit Shah <amit.shah@redhat.com>
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(cherry picked from commit 131fe9b843f9a1e55fcbf2457c9cb25c3711b9d8)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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migration-fd.c | 24 ++++++++++++++++++++++--
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1 file changed, 22 insertions(+), 2 deletions(-)
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diff --git a/migration-fd.c b/migration-fd.c
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index 3d4613c..3c98c3c 100644
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--- a/migration-fd.c
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+++ b/migration-fd.c
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@@ -30,13 +30,29 @@
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do { } while (0)
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#endif
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+static bool fd_is_socket(int fd)
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+{
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+ struct stat stat;
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+ int ret = fstat(fd, &stat;;
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+ if (ret == -1) {
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+ /* When in doubt say no */
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+ return false;
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+ }
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+ return S_ISSOCK(stat.st_mode);
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+}
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+
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void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp)
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{
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int fd = monitor_get_fd(cur_mon, fdname, errp);
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if (fd == -1) {
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return;
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}
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- s->file = qemu_fdopen(fd, "wb");
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+
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+ if (fd_is_socket(fd)) {
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+ s->file = qemu_fopen_socket(fd, "wb");
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+ } else {
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+ s->file = qemu_fdopen(fd, "wb");
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+ }
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migrate_fd_connect(s);
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}
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@@ -57,7 +73,11 @@ void fd_start_incoming_migration(const char *infd, Error **errp)
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DPRINTF("Attempting to start an incoming migration via fd\n");
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fd = strtol(infd, NULL, 0);
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- f = qemu_fdopen(fd, "rb");
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+ if (fd_is_socket(fd)) {
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+ f = qemu_fopen_socket(fd, "rb");
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+ } else {
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+ f = qemu_fdopen(fd, "rb");
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+ }
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if(f == NULL) {
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error_setg_errno(errp, errno, "failed to open the source descriptor");
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return;
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--
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1.8.3.1
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