A VM in the cloud environment may use a virutal disk as the backend storage,
and there are usually filesystems on the virtual block device. When backend
storage is temporarily down, any I/O issued to the virtual block device
will cause an error. For example, an error occurred in ext4 filesystem would
make the filesystem readonly. In production environment, a cloud backend
storage can be soon recovered. For example, an IP-SAN may be down due to
network failure and will be online soon after network is recovered. However,
the error in the filesystem may not be recovered unless a device reattach
or system restart. Thus an I/O retry mechanism is in need to implement a
self-healing system.
This patch series propose to extend the werror=/rerror= mechanism to add
a 'retry' feature. It can automatically retry failed I/O requests on error
without sending error back to guest, and guest can get back running smoothly
when I/O is recovred.
Jiahui Cen (9):
qapi/block-core: Add retry option for error action
block-backend: Introduce retry timer
block-backend: Add device specific retry callback
block-backend: Enable retry action on errors
block-backend: Add timeout support for retry
block: Add error retry param setting
virtio_blk: Add support for retry on errors
scsi-bus: Refactor the code that retries requests
scsi-disk: Add support for retry on errors
Sergio Lopez (2):
virtio-blk: Refactor the code that processes queued requests
virtio-blk: On restart, process queued requests in the proper context
block/block-backend.c | 66 ++++++++++++++++++++
blockdev.c | 52 +++++++++++++++
hw/block/block.c | 10 +++
hw/block/dataplane/virtio-blk.c | 8 +++
hw/block/virtio-blk.c | 51 +++++++++++----
hw/scsi/scsi-bus.c | 16 +++--
hw/scsi/scsi-disk.c | 16 +++++
include/hw/block/block.h | 7 ++-
include/hw/scsi/scsi.h | 1 +
include/hw/virtio/virtio-blk.h | 1 +
include/sysemu/block-backend.h | 10 +++
qapi/block-core.json | 4 +-
12 files changed, 222 insertions(+), 20 deletions(-)
--
2.30.0