Public bug reported:
My qemu version is 1.7.1,but when I try to make live snapshot by
libvirt,the libvirt sometimes report an error
:qemuMonitorJSONCheckError:377 : internal error: unable to execute QEMU
command 'transaction': An IO error has occurred.
Here is the command being snpshot create by virsh:
virsh snapshot-create snapshot-test.vm snapshot.xml --no-metadata
--disk-only --reuse-external
the snapshot.xml:
<domainsnapshot>
<description>test</description>
<disks>
<disk name='vda' snapshot="external">
<source dev='/home/disk/sbd8' file='/home/disk/sdb8' type="block"/>
</disk>
</disks>
</domainsnapshot>
I have read the qemu code about the snapshot create, and I find the qemu when
call the function handle_aiocb_rw_linear():
static ssize_t handle_aiocb_rw_linear(RawPosixAIOData *aiocb, char *buf)
{
ssize_t offset = 0;
ssize_t len;
while (offset < aiocb->aio_nbytes) {
if (aiocb->aio_type & QEMU_AIO_WRITE) {
len = pwrite(aiocb->aio_fildes,
(const char *)buf + offset,
aiocb->aio_nbytes - offset,
aiocb->aio_offset + offset);
} else {
len = pread(aiocb->aio_fildes,
buf + offset,
aiocb->aio_nbytes - offset,
aiocb->aio_offset + offset);
}
if (len == -1 && errno == EINTR) {
continue;
} else if (len == -1) {
offset = -errno;
break;
} else if (len == 0) {
break;
}
offset += len;
}
return offset;
}
The function pwrite happen error,the errono is 1,and the error
describe:"pwrite failed, Operation not permitted (1, EPERM) because the
process does not have the appropriate privileges to use the pwrite system call".
The qemu call stack about is:
external_snapshot_prepare()->bdrv_flush()->...->paio_submit->...->handle_aiocb_rw_linear.
** Affects: qemu
Importance: Undecided
Status: New
--
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https://bugs.launchpad.net/bugs/1505652
Title:
An IO error happen when qemu snapshot-create
Status in QEMU:
New
Bug description:
My qemu version is 1.7.1,but when I try to make live snapshot by
libvirt,the libvirt sometimes report an error
:qemuMonitorJSONCheckError:377 : internal error: unable to execute
QEMU command 'transaction': An IO error has occurred.
Here is the command being snpshot create by virsh:
virsh snapshot-create snapshot-test.vm snapshot.xml --no-metadata
--disk-only --reuse-external
the snapshot.xml:
<domainsnapshot>
<description>test</description>
<disks>
<disk name='vda' snapshot="external">
<source dev='/home/disk/sbd8' file='/home/disk/sdb8' type="block"/>
</disk>
</disks>
</domainsnapshot>
I have read the qemu code about the snapshot create, and I find the qemu when
call the function handle_aiocb_rw_linear():
static ssize_t handle_aiocb_rw_linear(RawPosixAIOData *aiocb, char *buf)
{
ssize_t offset = 0;
ssize_t len;
while (offset < aiocb->aio_nbytes) {
if (aiocb->aio_type & QEMU_AIO_WRITE) {
len = pwrite(aiocb->aio_fildes,
(const char *)buf + offset,
aiocb->aio_nbytes - offset,
aiocb->aio_offset + offset);
} else {
len = pread(aiocb->aio_fildes,
buf + offset,
aiocb->aio_nbytes - offset,
aiocb->aio_offset + offset);
}
if (len == -1 && errno == EINTR) {
continue;
} else if (len == -1) {
offset = -errno;
break;
} else if (len == 0) {
break;
}
offset += len;
}
return offset;
}
The function pwrite happen error,the errono is 1,and the error
describe:"pwrite failed, Operation not permitted (1, EPERM) because the
process does not have the appropriate privileges to use the pwrite system call".
The qemu call stack about is:
external_snapshot_prepare()->bdrv_flush()->...->paio_submit->...->handle_aiocb_rw_linear.
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