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blockdev: reset werror/rerror on drive_del

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Paolo Bonzini <pbonzini@redhat.com> suggested the following test case:

1. Launch a guest and wait at the GRUB boot menu:

  qemu-system-x86_64 -enable-kvm -m 1024 \
   -drive if=none,cache=none,file=test.img,id=foo,werror=stop,rerror=stop
   -device virtio-blk-pci,drive=foo,id=virtio0,addr=4

2. Hot unplug the device:

  (qemu) drive_del foo

3. Select the first boot menu entry

Without this patch the guest pauses due to ENOMEDIUM.  The guest is
stuck in a continuous pause loop since the I/O request is retried and
fails immediately again when the guest is resumed.

With this patch the error is reported to the guest.

Note that this scenario actually happens sometimes during libvirt disk
hot unplug, where device_del is followed by drive_del.  I/O may still be
submitted to the drive after drive_del if the guest does not process the
PCI hot unplug notification.

Reported-by: Dafna Ron <dron@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2013-06-05 10:33:14 +02:00
parent 8819c10b5d
commit 293c51a6ee
2 changed files with 6 additions and 0 deletions
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4
blockdev.c
View File

@ -1180,6 +1180,10 @@ int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
*/
if (bdrv_get_attached_dev(bs)) {
bdrv_make_anon(bs);
/* Further I/O must not pause the guest */
bdrv_set_on_error(bs, BLOCKDEV_ON_ERROR_REPORT,
BLOCKDEV_ON_ERROR_REPORT);
} else {
drive_uninit(drive_get_by_blockdev(bs));
}

2
hmp-commands.hx
View File

@ -185,6 +185,8 @@ Remove host block device. The result is that guest generated IO is no longer
submitted against the host device underlying the disk. Once a drive has
been deleted, the QEMU Block layer returns -EIO which results in IO
errors in the guest for applications that are reading/writing to the device.
These errors are always reported to the guest, regardless of the drive's error
actions (drive options rerror, werror).
ETEXI
{