On Mon, Mar 04, 2024 at 09:26:32AM +0800, pet...@redhat.com wrote:
> From: Fabiano Rosas <faro...@suse.de>
>
> If we receive a file descriptor that points to a regular file, there's
> nothing stopping us from doing multifd migration with mapped-ram to
> that file.
>
> Enable the fd: URI to work with multifd + mapped-ram.
>
> Note that the fds passed into multifd are duplicated because we want
> to avoid cross-thread effects when doing cleanup (i.e. close(fd)). The
> original fd doesn't need to be duplicated because monitor_get_fd()
> transfers ownership to the caller.
>
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
> Reviewed-by: Peter Xu <pet...@redhat.com>
> Link: https://lore.kernel.org/r/20240229153017.2221-23-faro...@suse.de
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> migration/fd.h | 2 ++
> migration/fd.c | 44 +++++++++++++++++++++++++++++++++++++++++++
> migration/file.c | 18 ++++++++++++------
> migration/migration.c | 4 ++++
> migration/multifd.c | 2 ++
> 5 files changed, 64 insertions(+), 6 deletions(-)
>
> @@ -73,4 +98,23 @@ 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(dup(fd)));
> +
> + if (QIO_CHANNEL_FILE(ioc)->fd == -1) {
> + error_setg(errp, "Failed to duplicate fd %d", fd);
> + return;
> + }
I'd suggest that Peter's comment about failure checks be fixed
by introducing a new constructor that handles the dup + error
reporting.
QIOChannel *qio_channel_file_new_dupfd(int fd, Error **errp;)
so we're not repeating the error reporting multiple places.
> +
> + 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());
> + }
> + }
> }
With regards,
Daniel
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