On Tue, Feb 20, 2024 at 07:41:24PM -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.
>
> Contrary to the socket migration, the file migration doesn't need an
> asynchronous channel creation process, so expose
> multifd_channel_connect() and call it directly.
>
> Note that this is just setup code and multifd cannot yet make use of
> the file channels.
>
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
> migration/file.c | 40 ++++++++++++++++++++++++++++++++++++++--
> migration/file.h | 5 +++++
> migration/multifd.c | 27 ++++++++++++++++++++++-----
> migration/multifd.h | 2 ++
> 4 files changed, 67 insertions(+), 7 deletions(-)
>
> diff --git a/migration/file.c b/migration/file.c
> index 22d052a71f..ac9f6ae40a 100644
> --- a/migration/file.c
> +++ b/migration/file.c
> @@ -12,12 +12,17 @@
> #include "channel.h"
> #include "file.h"
> #include "migration.h"
> +#include "multifd.h"
> #include "io/channel-file.h"
> #include "io/channel-util.h"
> #include "trace.h"
>
> #define OFFSET_OPTION ",offset="
>
> +static struct FileOutgoingArgs {
> + char *fname;
> +} outgoing_args;
> +
> /* Remove the offset option from @filespec and return it in @offsetp. */
>
> int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp)
> @@ -37,6 +42,34 @@ int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp)
> return 0;
> }
>
> +int file_send_channel_destroy(QIOChannel *ioc)
> +{
> + if (ioc) {
> + qio_channel_close(ioc, NULL);
> + }
> + g_free(outgoing_args.fname);
> + outgoing_args.fname = NULL;
> +
> + return 0;
> +}
> +
> +bool file_send_channel_create(gpointer opaque, Error **errp)
> +{
> + QIOChannelFile *ioc;
> + int flags = O_WRONLY;
> +
> + 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)) {
> + return false;
> + }
> +
> + return true;
> +}
> +
> void file_start_outgoing_migration(MigrationState *s,
> FileMigrationArgs *file_args, Error **errp)
> {
> @@ -44,15 +77,18 @@ void file_start_outgoing_migration(MigrationState *s,
> g_autofree char *filename = g_strdup(file_args->filename);
> uint64_t offset = file_args->offset;
> QIOChannel *ioc;
> + int flags = O_CREAT | O_TRUNC | O_WRONLY;
> + mode_t mode = 0660;
>
> trace_migration_file_outgoing(filename);
>
> - 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);
This change seems irrelevant, could be squashed into the previous patch
when introduced?
> if (!fioc) {
> return;
> }
>
> + outgoing_args.fname = g_strdup(filename);
> +
> ioc = QIO_CHANNEL(fioc);
> if (offset && qio_channel_io_seek(ioc, offset, SEEK_SET, errp) < 0) {
> return;
> diff --git a/migration/file.h b/migration/file.h
> index 37d6a08bfc..90794b494b 100644
> --- a/migration/file.h
> +++ b/migration/file.h
> @@ -9,10 +9,15 @@
> #define QEMU_MIGRATION_FILE_H
>
> #include "qapi/qapi-types-migration.h"
> +#include "io/task.h"
> +#include "channel.h"
>
> void file_start_incoming_migration(FileMigrationArgs *file_args, Error **errp);
>
> void file_start_outgoing_migration(MigrationState *s,
> FileMigrationArgs *file_args, Error **errp);
> int file_parse_offset(char *filespec, uint64_t *offsetp, Error **errp);
> +
> +bool file_send_channel_create(gpointer opaque, Error **errp);
> +int file_send_channel_destroy(QIOChannel *ioc);
> #endif
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 45a0c7aaa8..507b497d52 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -17,6 +17,7 @@
> #include "exec/ramblock.h"
> #include "qemu/error-report.h"
> #include "qapi/error.h"
> +#include "file.h"
> #include "ram.h"
> #include "migration.h"
> #include "migration-stats.h"
> @@ -28,6 +29,7 @@
> #include "threadinfo.h"
> #include "options.h"
> #include "qemu/yank.h"
> +#include "io/channel-file.h"
> #include "io/channel-socket.h"
> #include "yank_functions.h"
>
> @@ -680,6 +682,9 @@ static void multifd_send_terminate_threads(void)
>
> static int multifd_send_channel_destroy(QIOChannel *send)
> {
> + if (!multifd_use_packets()) {
> + return file_send_channel_destroy(send);
> + }
> return socket_send_channel_destroy(send);
> }
>
> @@ -959,9 +964,8 @@ static bool multifd_tls_channel_connect(MultiFDSendParams *p,
> return true;
> }
>
> -static bool multifd_channel_connect(MultiFDSendParams *p,
> - QIOChannel *ioc,
> - Error **errp)
> +bool multifd_channel_connect(MultiFDSendParams *p, QIOChannel *ioc,
> + Error **errp)
> {
> qio_channel_set_delay(ioc, false);
>
> @@ -1031,9 +1035,14 @@ out:
> error_free(local_err);
> }
>
> -static void multifd_new_send_channel_create(gpointer opaque)
> +static bool multifd_new_send_channel_create(gpointer opaque, Error **errp)
> {
> + if (!multifd_use_packets()) {
> + return file_send_channel_create(opaque, errp);
> + }
> +
> socket_send_channel_create(multifd_new_send_channel_async, opaque);
> + return true;
> }
>
> bool multifd_send_setup(void)
> @@ -1082,7 +1091,15 @@ bool multifd_send_setup(void)
> p->page_size = qemu_target_page_size();
> p->page_count = page_count;
> p->write_flags = 0;
> - multifd_new_send_channel_create(p);
> +
> + if (!multifd_new_send_channel_create(p, &local_err)) {
> + /*
> + * File channel creation is synchronous, we don't need the
> + * semaphore below, it's safe to return now.
> + */
> + assert(migrate_fixed_ram());
This comment and assert() is slightly confusing to me. Drop them?
IMHO it's always safe to directly return here, the channels_created sem
will be destroyed later anyway so the number shouldn't matter.
And as I commented in the other email, IMHO it's cleaner we also post that
sem in file_send_channel_create().
> + return -1;
> + }
> }
>
> if (use_packets) {
> diff --git a/migration/multifd.h b/migration/multifd.h
> index 19188815a3..135f6ed098 100644
> --- a/migration/multifd.h
> +++ b/migration/multifd.h
> @@ -228,5 +228,7 @@ static inline void multifd_send_prepare_header(MultiFDSendParams *p)
> p->iovs_num++;
> }
>
> +bool multifd_channel_connect(MultiFDSendParams *p, QIOChannel *ioc,
> + Error **errp);
>
> #endif
> --
> 2.35.3
>
--
Peter Xu