Signed-off-by: Fabiano Rosas <faro...@suse.de>
---
migration/file.c | 18 +++++++++++++++++-
migration/migration.c | 24 ++++++++++++++++++++++++
migration/options.h | 1 +
util/osdep.c | 9 +++++++++
4 files changed, 51 insertions(+), 1 deletion(-)
diff --git a/migration/file.c b/migration/file.c
index 27ccfc6a1d..f1c7615fb6 100644
--- a/migration/file.c
+++ b/migration/file.c
@@ -57,10 +57,26 @@ int file_send_channel_destroy(QIOChannel *ioc)
bool file_send_channel_create(gpointer opaque, Error **errp)
{
- QIOChannelFile *ioc;
+ QIOChannelFile *ioc = NULL;
int flags = O_WRONLY;
int fd = fd_args_get_fd();
+ if (migrate_direct_io()) {
+#ifdef O_DIRECT
+ /*
+ * Enable O_DIRECT for the secondary channels. These are used
+ * for sending ram pages and writes should be guaranteed to be
+ * aligned to at least page size.
+ */
+ flags |= O_DIRECT;
+#else
+ error_setg(errp, "System does not support O_DIRECT");
+ error_append_hint(errp,
+ "Try disabling direct-io migration capability\n");
+ return false;
+#endif
+ }
+
if (fd && fd != -1) {
ioc = qio_channel_file_new_fd(fd);
} else {
diff --git a/migration/migration.c b/migration/migration.c
index ce7e6f5065..ecc07c4847 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -153,6 +153,16 @@ static bool migration_needs_seekable_channel(void)
return migrate_fixed_ram();
}
+static bool migration_needs_multiple_fds(void)
+{
+ /*
+ * When doing direct-io, multifd requires two different,
+ * non-duplicated file descriptors so we can use one of them for
+ * unaligned IO.
+ */
+ return migrate_multifd() && migrate_direct_io();
+}
+
static bool transport_supports_seeking(MigrationAddress *addr)
{
if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
@@ -171,6 +181,12 @@ static bool transport_supports_seeking(MigrationAddress
*addr)
return false;
}
+static bool transport_supports_multiple_fds(MigrationAddress *addr)
+{
+ /* file: works because QEMU can open it multiple times */
+ return addr->transport == MIGRATION_ADDRESS_TYPE_FILE;
+}
+
static bool
migration_channels_and_transport_compatible(MigrationAddress *addr,
Error **errp)
@@ -187,6 +203,14 @@
migration_channels_and_transport_compatible(MigrationAddress *addr,
return false;
}
+ if (migration_needs_multiple_fds() &&
+ !transport_supports_multiple_fds(addr)) {
+ error_setg(errp,
+ "Migration with direct-io is incompatible with the fd: URI,"
+ " use file: instead");
+ return false;
+ }
+
return true;
}
diff --git a/migration/options.h b/migration/options.h
index 8680a10b79..39cbc171f7 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -79,6 +79,7 @@ uint8_t migrate_cpu_throttle_increment(void);
uint8_t migrate_cpu_throttle_initial(void);
bool migrate_cpu_throttle_tailslow(void);
int migrate_decompress_threads(void);
+bool migrate_direct_io(void);
uint64_t migrate_downtime_limit(void);
uint8_t migrate_max_cpu_throttle(void);
uint64_t migrate_max_bandwidth(void);
diff --git a/util/osdep.c b/util/osdep.c
index e996c4744a..d0227a60ab 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -277,6 +277,15 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len,
bool exclusive)
}
#endif
+bool qemu_has_direct_io(void)
+{
+#ifdef O_DIRECT
+ return true;
+#else
+ return false;
+#endif
+}
+
static int qemu_open_cloexec(const char *name, int flags, mode_t mode)
{
int ret;
--
2.35.3
