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migration: add FEATURE_SEEKABLE to QIOChannelBlock

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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>
Link: https://lore.kernel.org/r/20251010115954.1995298-2-Marco.Cavenati@eurecom.fr
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
Marco Cavenati
2025-10-10 13:59:53 +02:00
committed by Peter Xu
parent e5423828d6
commit 04a191cb36
1 changed files with 44 additions and 0 deletions
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44
migration/channel-block.c
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@@ -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 +97,47 @@ qio_channel_block_writev(QIOChannel *ioc,
return qiov.size;
}
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;
}
static int
qio_channel_block_set_blocking(QIOChannel *ioc,
@@ -177,6 +219,8 @@ 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;
ioc_klass->io_preadv = qio_channel_block_preadv;
ioc_klass->io_pwritev = qio_channel_block_pwritev;
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;