On Tue, Feb 20, 2024 at 07:41:29PM -0300, Fabiano Rosas wrote:
> If we receive a file descriptor that points to a regular file, there's
> nothing stopping us from doing multifd migration with fixed-ram to
> that file.
>
> Enable the fd: URI to work with multifd + fixed-ram.
>
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
> ---
> migration/fd.c | 30 ++++++++++++++++++++++++++++++
> migration/fd.h | 1 +
> migration/file.c | 12 +++++++++---
> migration/migration.c | 4 ++++
> 4 files changed, 44 insertions(+), 3 deletions(-)
>
> diff --git a/migration/fd.c b/migration/fd.c
> index 0eb677dcae..b7e4d071a4 100644
> --- a/migration/fd.c
> +++ b/migration/fd.c
> @@ -19,14 +19,28 @@
> #include "fd.h"
> #include "migration.h"
> #include "monitor/monitor.h"
> +#include "io/channel-file.h"
> #include "io/channel-util.h"
> +#include "options.h"
> #include "trace.h"
>
>
> +static struct FdOutgoingArgs {
> + int fd;
> +} outgoing_args;
> +
> +int fd_args_get_fd(void)
> +{
> + return outgoing_args.fd;
> +}
> +
> void fd_start_outgoing_migration(MigrationState *s, const char *fdname,
> Error **errp)
> {
> QIOChannel *ioc;
> int fd = monitor_get_fd(monitor_cur(), fdname, errp);
> +
> + outgoing_args.fd = -1;
I suggest we either drop this, or close() it before releasing; basically
each fd reference holds a real fd index would be easier, IMHO.
Also, we'd want to free the fd (by closing it) just like we free
outgoing_args.fname? Otherwise if a fd is passed in, who is responsible to
close it and release the fd resource?
> +
> if (fd == -1) {
> return;
> }
> @@ -38,6 +52,8 @@ void fd_start_outgoing_migration(MigrationState *s, const
> char *fdname, Error **
> return;
> }
>
> + outgoing_args.fd = fd;
If agree with above, then dup(fd) here.
> +
> qio_channel_set_name(ioc, "migration-fd-outgoing");
> migration_channel_connect(s, ioc, NULL, NULL);
> object_unref(OBJECT(ioc));
> @@ -73,4 +89,18 @@ void fd_start_incoming_migration(const char *fdname, Error
> **errp)
> fd_accept_incoming_migration,
> NULL, NULL,
> g_main_context_get_thread_default());
> +
> + if (migrate_multifd()) {
> + int channels = migrate_multifd_channels();
> +
> + while (channels--) {
> + ioc = QIO_CHANNEL(qio_channel_file_new_fd(fd));
dup(fd)?
> +
> + qio_channel_set_name(ioc, "migration-fd-incoming");
> + qio_channel_add_watch_full(ioc, G_IO_IN,
> + fd_accept_incoming_migration,
> + NULL, NULL,
> + g_main_context_get_thread_default());
> + }
> + }
> }
> diff --git a/migration/fd.h b/migration/fd.h
> index b901bc014e..1be980c130 100644
> --- a/migration/fd.h
> +++ b/migration/fd.h
> @@ -20,4 +20,5 @@ void fd_start_incoming_migration(const char *fdname, Error
> **errp);
>
> void fd_start_outgoing_migration(MigrationState *s, const char *fdname,
> Error **errp);
> +int fd_args_get_fd(void);
> #endif
> diff --git a/migration/file.c b/migration/file.c
> index 1a18e608fc..27ccfc6a1d 100644
> --- a/migration/file.c
> +++ b/migration/file.c
> @@ -11,6 +11,7 @@
> #include "qemu/error-report.h"
> #include "qapi/error.h"
> #include "channel.h"
> +#include "fd.h"
> #include "file.h"
> #include "migration.h"
> #include "io/channel-file.h"
> @@ -58,10 +59,15 @@ bool file_send_channel_create(gpointer opaque, Error
> **errp)
> {
> QIOChannelFile *ioc;
> int flags = O_WRONLY;
> + int fd = fd_args_get_fd();
>
> - ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp);
> - if (!ioc) {
> - return false;
> + if (fd && fd != -1) {
> + ioc = qio_channel_file_new_fd(fd);
> + } else {
> + ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp);
> + if (!ioc) {
> + return false;
> + }
> }
>
> if (!multifd_channel_connect(opaque, QIO_CHANNEL(ioc), errp)) {
> diff --git a/migration/migration.c b/migration/migration.c
> index 32b291a282..ce7e6f5065 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -134,6 +134,10 @@ static bool
> transport_supports_multi_channels(MigrationAddress *addr)
> if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
> SocketAddress *saddr = &addr->u.socket;
>
> + if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
> + return migrate_fixed_ram();
> + }
> +
> return (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
> saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
> saddr->type == SOCKET_ADDRESS_TYPE_VSOCK);
> --
> 2.35.3
>
--
Peter Xu
