On Mon, Oct 23, 2023 at 05:35:58PM -0300, Fabiano Rosas wrote:
> Allow multifd to open file-backed channels. This will be used when
> enabling the fixed-ram migration stream format which expects a
> seekable transport.
>
> The QIOChannel read and write methods will use the preadv/pwritev
> versions which don't update the file offset at each call so we can
> reuse the fd without re-opening for every channel.
>
> Note that this is just setup code and multifd cannot yet make use of
> the file channels.
>
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
> ---
> migration/file.c | 64 +++++++++++++++++++++++++++++++++++++++++--
> migration/file.h | 10 +++++--
> migration/migration.c | 2 +-
> migration/multifd.c | 14 ++++++++--
> migration/options.c | 7 +++++
> migration/options.h | 1 +
> 6 files changed, 90 insertions(+), 8 deletions(-)
>
> diff --git a/migration/file.c b/migration/file.c
> index cf5b1bf365..93b9b7bf5d 100644
> --- a/migration/file.c
> +++ b/migration/file.c
> @@ -17,6 +17,12 @@
> +void file_send_channel_create(QIOTaskFunc f, void *data)
> +{
> + QIOChannelFile *ioc;
> + QIOTask *task;
> + Error *errp = NULL;
> +
> + ioc = qio_channel_file_new_path(outgoing_args.fname,
> + outgoing_args.flags,
> + outgoing_args.mode, &errp);
> + if (!ioc) {
> + file_migration_cancel(errp);
> + return;
> + }
> +
> + task = qio_task_new(OBJECT(ioc), f, (gpointer)data, NULL);
> + qio_task_run_in_thread(task, qio_channel_file_connect_worker,
> + (gpointer)data, NULL, NULL);
> +}
> +
> void file_start_outgoing_migration(MigrationState *s, const char *filespec,
> Error **errp)
> {
> - g_autofree char *filename = g_strdup(filespec);
> g_autoptr(QIOChannelFile) fioc = NULL;
> + g_autofree char *filename = g_strdup(filespec);
> uint64_t offset = 0;
> QIOChannel *ioc;
> + int flags = O_CREAT | O_TRUNC | O_WRONLY;
> + mode_t mode = 0660;
>
> trace_migration_file_outgoing(filename);
>
> @@ -50,12 +105,15 @@ void file_start_outgoing_migration(MigrationState *s,
> const char *filespec,
> return;
> }
>
> - fioc = qio_channel_file_new_path(filename, O_CREAT | O_WRONLY | O_TRUNC,
> - 0600, errp);
> + fioc = qio_channel_file_new_path(filename, flags, mode, errp);
So this initially opens the file with O_CREAT|O_TRUNC which
makes sense.
> if (!fioc) {
> return;
> }
>
> + outgoing_args.fname = g_strdup(filename);
> + outgoing_args.flags = flags;
> + outgoing_args.mode = mode;
We're passing on O_CREAT|O_TRUNC to all the multifd threads too. This
doesn't make sense to me - the file should already exist and be truncated
by the time the threads open it. I would think they should only be using
O_WRONLY and no mode at all.
With regards,
Daniel
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