Peter Xu <pet...@redhat.com> writes:
> On Thu, Feb 29, 2024 at 10:44:21AM +0800, Peter Xu wrote:
>> On Wed, Feb 28, 2024 at 12:21:21PM -0300, Fabiano Rosas wrote:
>> > Allow multifd to open file-backed channels. This will be used when
>> > enabling the mapped-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 <faro...@suse.de>
>> > ---
>> > - moved flags change to another patch
>> > - removed channels_created assert
>> > ---
>> > migration/file.c | 41 +++++++++++++++++++++++++++++++++++++++--
>> > migration/file.h | 4 ++++
>> > migration/multifd.c | 18 +++++++++++++++---
>> > migration/multifd.h | 1 +
>> > 4 files changed, 59 insertions(+), 5 deletions(-)
>> >
>> > diff --git a/migration/file.c b/migration/file.c
>> > index 22d052a71f..83328a7a1b 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 +42,36 @@ int file_parse_offset(char *filespec, uint64_t
>> > *offsetp, Error **errp)
>> > return 0;
>> > }
>> >
>> > +void file_cleanup_outgoing_migration(void)
>> > +{
>> > + g_free(outgoing_args.fname);
>> > + outgoing_args.fname = NULL;
>> > +}
>> > +
>> > +bool file_send_channel_create(gpointer opaque, Error **errp)
>> > +{
>> > + QIOChannelFile *ioc;
>> > + int flags = O_WRONLY;
>> > + bool ret = true;
>> > +
>> > + ioc = qio_channel_file_new_path(outgoing_args.fname, flags, 0, errp);
>> > + if (!ioc) {
>> > + ret = false;
>> > + goto out;
>> > + }
>> > +
>> > + multifd_channel_connect(opaque, QIO_CHANNEL(ioc));
>> > +
>> > +out:
>> > + /*
>> > + * File channel creation is synchronous. However posting this
>> > + * semaphore here is simpler than adding a special case.
>> > + */
>> > + multifd_send_channel_created();
>> > +
>> > + return ret;
>> > +}
>> > +
>> > void file_start_outgoing_migration(MigrationState *s,
>> > FileMigrationArgs *file_args, Error
>> > **errp)
>> > {
>> > @@ -47,12 +82,14 @@ void file_start_outgoing_migration(MigrationState *s,
>> >
>> > 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, O_CREAT | O_TRUNC |
>> > O_WRONLY,
>> > + 0660, errp);
>>
>> It seems this is still leftover?
>>
>> > 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..4577f9efdd 100644
>> > --- a/migration/file.h
>> > +++ b/migration/file.h
>> > @@ -9,10 +9,14 @@
>> > #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);
>> > +void file_cleanup_outgoing_migration(void);
>> > +bool file_send_channel_create(gpointer opaque, Error **errp);
>> > #endif
>> > diff --git a/migration/multifd.c b/migration/multifd.c
>> > index 3574fd3953..f155223303 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"
>> >
>> > @@ -694,6 +696,7 @@ static bool
>> > multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp)
>> > {
>> > if (p->c) {
>> > migration_ioc_unregister_yank(p->c);
>> > + qio_channel_close(p->c, NULL);
>>
>> s/NULL/&error_abort/?
>
> Or we can drop this line? IIUC iochannel finalize() will always close it,
> or it could be a separate bug.
>
We need it so the fsync happens. The finalize() will be a noop because
the qio_channel_file_close() will clear the fd. Not the cleanest, but it
works.
>>
>> > object_unref(OBJECT(p->c));
>> > p->c = NULL;
>> > }
>> > @@ -715,6 +718,7 @@ static bool
>> > multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp)
>> >
>> > static void multifd_send_cleanup_state(void)
>> > {
>> > + file_cleanup_outgoing_migration();
>> > socket_cleanup_outgoing_migration();
>> > qemu_sem_destroy(&multifd_send_state->channels_created);
>> > qemu_sem_destroy(&multifd_send_state->channels_ready);
>> > @@ -977,7 +981,7 @@ static bool
>> > multifd_tls_channel_connect(MultiFDSendParams *p,
>> > return true;
>> > }
>> >
>> > -static void multifd_channel_connect(MultiFDSendParams *p, QIOChannel *ioc)
>> > +void multifd_channel_connect(MultiFDSendParams *p, QIOChannel *ioc)
>> > {
>> > qio_channel_set_delay(ioc, false);
>> >
>> > @@ -1045,9 +1049,14 @@ 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)
>> > @@ -1096,7 +1105,10 @@ 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)) {
>> > + return -1;
>>
>> "-1" is unfortunately a "true"!..
>>
>> > + }
>> > }
>> >
>> > /*
>> > diff --git a/migration/multifd.h b/migration/multifd.h
>> > index 1d8bbaf96b..db8887f088 100644
>> > --- a/migration/multifd.h
>> > +++ b/migration/multifd.h
>> > @@ -227,5 +227,6 @@ static inline void
>> > multifd_send_prepare_header(MultiFDSendParams *p)
>> > p->iovs_num++;
>> > }
>> >
>> > +void multifd_channel_connect(MultiFDSendParams *p, QIOChannel *ioc);
>> >
>> > #endif
>> > --
>> > 2.35.3
>> >
>>
>> --
>> Peter Xu
