[PATCH 1/1] Drivers: hv: Add a new driver to support host initiated backup

[KY Srinivasan]

> -----Original Message-----
> From: K. Y. Srinivasan [mailto:kys at microsoft.com]
> Sent: Tuesday, March 12, 2013 2:29 PM
> To: gregkh at linuxfoundation.org; linux-kernel at vger.kernel.org;
> devel at linuxdriverproject.org; olaf at aepfle.de; apw at canonical.com;
> jasowang at redhat.com
> Cc: KY Srinivasan
> Subject: [PATCH 1/1] Drivers: hv: Add a new driver to support host initiated
> backup
> 
> This driver supports host initiated backup of the guest. On Windows guests,
> the host can generate application consistent backups using the Windows VSS
> framework. On Linux, we ensure that the backup will be file system consistent.
> This driver allows the host to initiate a  "Freeze" operation on all the mounted
> file systems in the guest. Once the mounted file systems in the guest are frozen,
> the host snapshots the guest's file systems. Once this is done, the guest's file
> systems are "thawed".
> 
> This driver has a user-level component (daemon) that invokes the appropriate
> operation on all the mounted file systems in response to the requests from
> the host. The duration for which the guest is frozen is very short - a few seconds.
> During this interval, the diff disk is comitted.
> 
> Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
> Reviewed-by: Haiyang Zhang <haiyangz at microsoft.com>

Greg,

Please drop this patch. I sent the wrong patch.

K. Y
> ---
>  drivers/hv/Makefile            |    2 +-
>  drivers/hv/hv_util.c           |   10 ++++++
>  include/linux/hyperv.h         |   69
> ++++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/connector.h |    5 ++-
>  4 files changed, 84 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
> index e6abfa0..0a74b56 100644
> --- a/drivers/hv/Makefile
> +++ b/drivers/hv/Makefile
> @@ -5,4 +5,4 @@ obj-$(CONFIG_HYPERV_BALLOON)	+= hv_balloon.o
>  hv_vmbus-y := vmbus_drv.o \
>  		 hv.o connection.o channel.o \
>  		 channel_mgmt.o ring_buffer.o
> -hv_utils-y := hv_util.o hv_kvp.o
> +hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o
> diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
> index 1d4cbd8..2f561c5 100644
> --- a/drivers/hv/hv_util.c
> +++ b/drivers/hv/hv_util.c
> @@ -49,6 +49,12 @@ static struct hv_util_service util_kvp = {
>  	.util_deinit = hv_kvp_deinit,
>  };
> 
> +static struct hv_util_service util_vss = {
> +	.util_cb = hv_vss_onchannelcallback,
> +	.util_init = hv_vss_init,
> +	.util_deinit = hv_vss_deinit,
> +};
> +
>  static void perform_shutdown(struct work_struct *dummy)
>  {
>  	orderly_poweroff(true);
> @@ -339,6 +345,10 @@ static const struct hv_vmbus_device_id id_table[] = {
>  	{ HV_KVP_GUID,
>  	  .driver_data = (unsigned long)&util_kvp
>  	},
> +	/* VSS GUID */
> +	{ HV_VSS_GUID,
> +	  .driver_data = (unsigned long)&util_vss
> +	},
>  	{ },
>  };
> 
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index df77ba9..95d0850 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -27,6 +27,63 @@
> 
>  #include <linux/types.h>
> 
> +
> +/*
> + * Implementation of host controlled snapshot of the guest.
> + */
> +
> +#define VSS_OP_REGISTER 128
> +
> +enum hv_vss_op {
> +	VSS_OP_CREATE = 0,
> +	VSS_OP_DELETE,
> +	VSS_OP_HOT_BACKUP,
> +	VSS_OP_GET_DM_INFO,
> +	VSS_OP_BU_COMPLETE,
> +	/*
> +	 * Following operations are only supported with IC version >= 5.0
> +	 */
> +	VSS_OP_FREEZE, /* Freeze the file systems in the VM */
> +	VSS_OP_THAW, /* Unfreeze the file systems */
> +	VSS_OP_AUTO_RECOVER,
> +	VSS_OP_COUNT /* Number of operations, must be last */
> +};
> +
> +
> +/*
> + * Header for all VSS messages.
> + */
> +struct hv_vss_hdr {
> +	__u8 operation;
> +	__u8 reserved[7];
> +} __attribute__((packed));
> +
> +
> +/*
> + * Flag values for the hv_vss_check_feature. Linux supports only
> + * one value.
> + */
> +#define VSS_HBU_NO_AUTO_RECOVERY	0x00000005
> +
> +struct hv_vss_check_feature {
> +	__u32 flags;
> +} __attribute__((packed));
> +
> +struct hv_vss_check_dm_info {
> +	__u32 flags;
> +} __attribute__((packed));
> +
> +struct hv_vss_msg {
> +	union {
> +		struct hv_vss_hdr vss_hdr;
> +		int error;
> +	};
> +	union {
> +		struct hv_vss_check_feature vss_cf;
> +		struct hv_vss_check_dm_info dm_info;
> +	};
> +} __attribute__((packed));
> +
>  /*
>   * An implementation of HyperV key value pair (KVP) functionality for Linux.
>   *
> @@ -1253,6 +1310,14 @@ void vmbus_driver_unregister(struct hv_driver
> *hv_driver);
>  		}
> 
>  /*
> + * VSS (Backup/Restore) GUID
> + */
> +#define HV_VSS_GUID \
> +	.guid = { \
> +			0x29, 0x2e, 0xfa, 0x35, 0x23, 0xea, 0x36, 0x42, \
> +			0x96, 0xae, 0x3a, 0x6e, 0xba, 0xcb, 0xa4,  0x40 \
> +		}
> +/*
>   * Common header for Hyper-V ICs
>   */
> 
> @@ -1356,6 +1421,10 @@ int hv_kvp_init(struct hv_util_service *);
>  void hv_kvp_deinit(void);
>  void hv_kvp_onchannelcallback(void *);
> 
> +int hv_vss_init(struct hv_util_service *);
> +void hv_vss_deinit(void);
> +void hv_vss_onchannelcallback(void *);
> +
>  /*
>   * Negotiated version with the Host.
>   */
> diff --git a/include/uapi/linux/connector.h b/include/uapi/linux/connector.h
> index 8761a03..4cb2835 100644
> --- a/include/uapi/linux/connector.h
> +++ b/include/uapi/linux/connector.h
> @@ -44,8 +44,11 @@
>  #define CN_VAL_DRBD			0x1
>  #define CN_KVP_IDX			0x9	/* HyperV KVP */
>  #define CN_KVP_VAL			0x1	/* queries from the kernel */
> +#define CN_VSS_IDX			0xA     /* HyperV VSS */
> +#define CN_VSS_VAL			0x1     /* queries from the kernel */
> 
> -#define CN_NETLINK_USERS		10	/* Highest index + 1 */
> +
> +#define CN_NETLINK_USERS		11	/* Highest index + 1 */
> 
>  /*
>   * Maximum connector's message size.
> --
> 1.7.4.1
> 
>