@@ -30,6 +30,7 @@ qio_channel_block_new(BlockDriverState *bs)
QIOChannelBlock *ioc;
ioc = QIO_CHANNEL_BLOCK(object_new(TYPE_QIO_CHANNEL_BLOCK));
+ qio_channel_set_feature(QIO_CHANNEL(ioc), QIO_CHANNEL_FEATURE_SEEKABLE);
bdrv_ref(bs);
ioc->bs = bs;
@@ -96,6 +97,49 @@ qio_channel_block_writev(QIOChannel *ioc,
return qiov.size;
}
+#ifdef CONFIG_PREADV
+static ssize_t
+qio_channel_block_preadv(QIOChannel *ioc,
+ const struct iovec *iov,
+ size_t niov,
+ off_t offset,
+ Error **errp)
+{
+ QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc);
+ QEMUIOVector qiov;
+ int ret;
+
+ qemu_iovec_init_external(&qiov, (struct iovec *)iov, niov);
+ ret = bdrv_readv_vmstate(bioc->bs, &qiov, offset);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "bdrv_readv_vmstate failed");
+ return -1;
+ }
+
+ return qiov.size;
+}
+
+static ssize_t
+qio_channel_block_pwritev(QIOChannel *ioc,
+ const struct iovec *iov,
+ size_t niov,
+ off_t offset,
+ Error **errp)
+{
+ QIOChannelBlock *bioc = QIO_CHANNEL_BLOCK(ioc);
+ QEMUIOVector qiov;
+ int ret;
+
+ qemu_iovec_init_external(&qiov, (struct iovec *)iov, niov);
+ ret = bdrv_writev_vmstate(bioc->bs, &qiov, offset);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "bdrv_writev_vmstate failed");
+ return -1;
+ }
+
+ return qiov.size;
+}
+#endif /* CONFIG_PREADV */
static int
qio_channel_block_set_blocking(QIOChannel *ioc,
@@ -177,6 +221,10 @@ qio_channel_block_class_init(ObjectClass *klass,
ioc_klass->io_writev = qio_channel_block_writev;
ioc_klass->io_readv = qio_channel_block_readv;
ioc_klass->io_set_blocking = qio_channel_block_set_blocking;
+#ifdef CONFIG_PREADV
+ ioc_klass->io_preadv = qio_channel_block_preadv;
+ ioc_klass->io_pwritev = qio_channel_block_pwritev;
+#endif
ioc_klass->io_seek = qio_channel_block_seek;
ioc_klass->io_close = qio_channel_block_close;
ioc_klass->io_set_aio_fd_handler = qio_channel_block_set_aio_fd_handler;
Enable the use of the mapped-ram migration feature with savevm/loadvm snapshots by adding the QIO_CHANNEL_FEATURE_SEEKABLE feature to QIOChannelBlock. Implement io_preadv and io_pwritev methods to provide positioned I/O capabilities that don't modify the channel's position pointer. Signed-off-by: Marco Cavenati <Marco.Cavenati@eurecom.fr> --- Hello, Please note that this depends on my previous fix [0] (which has already been reviewed) in order to work. The code in this patch is inspired by commit 0478b030fa2530cbbfc4d6432e8e39a16d06865b that adds the same feature to QIOChannelFile. Thank you, Regards Marco [0] [PATCH] migration: fix SEEK_CUR offset calculation in qio_channel_block_seek https://lore.kernel.org/all/20250326162230.3323199-1-Marco.Cavenati@eurecom.fr/t/#u --- migration/channel-block.c | 48 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+)