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linux-hardened/include/linux/dm-log-userspace.h
Jonathan E Brassow 5a25f0eb70 dm log userspace: add log device dependency 
Allow userspace dm log implementations to register their log device so it
is no longer missing from the list of device dependencies.

When device mapper targets use a device they normally call dm_get_device
which includes it in the device list returned to userspace applications
such as LVM through the DM_TABLE_DEPS ioctl.  Userspace log devices
don't use dm_get_device as userspace opens them so they are missing from
the list of dependencies.

This patch extends the DM_ULOG_CTR operation to allow userspace to
respond with the name of the log device (if appropriate) to be
registered via 'dm_get_device'.  DM_ULOG_REQUEST_VERSION is incremented.

This is backwards compatible.  If the kernel and userspace log server
have both been updated, the new information will be passed down to the
kernel and the device will be registered.  If the kernel is new, but
the log server is old, the log server will not pass down any device
information and the kernel will simply bypass the device registration
as before.  If the kernel is old but the log server is new, the log
server will see the old version number and not pass the device info.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-10-31 20:21:24 +00:00

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/*
* Copyright (C) 2006-2009 Red Hat, Inc.
*
* This file is released under the LGPL.
*/
#ifndef __DM_LOG_USERSPACE_H__
#define __DM_LOG_USERSPACE_H__
#include <linux/dm-ioctl.h> /* For DM_UUID_LEN */
/*
* The device-mapper userspace log module consists of a kernel component and
* a user-space component. The kernel component implements the API defined
* in dm-dirty-log.h. Its purpose is simply to pass the parameters and
* return values of those API functions between kernel and user-space.
*
* Below are defined the 'request_types' - DM_ULOG_CTR, DM_ULOG_DTR, etc.
* These request types represent the different functions in the device-mapper
* dirty log API. Each of these is described in more detail below.
*
* The user-space program must listen for requests from the kernel (representing
* the various API functions) and process them.
*
* User-space begins by setting up the communication link (error checking
* removed for clarity):
* fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
* addr.nl_family = AF_NETLINK;
* addr.nl_groups = CN_IDX_DM;
* addr.nl_pid = 0;
* r = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
* opt = addr.nl_groups;
* setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &opt, sizeof(opt));
*
* User-space will then wait to receive requests form the kernel, which it
* will process as described below. The requests are received in the form,
* ((struct dm_ulog_request) + (additional data)). Depending on the request
* type, there may or may not be 'additional data'. In the descriptions below,
* you will see 'Payload-to-userspace' and 'Payload-to-kernel'. The
* 'Payload-to-userspace' is what the kernel sends in 'additional data' as
* necessary parameters to complete the request. The 'Payload-to-kernel' is
* the 'additional data' returned to the kernel that contains the necessary
* results of the request. The 'data_size' field in the dm_ulog_request
* structure denotes the availability and amount of payload data.
*/
/*
* DM_ULOG_CTR corresponds to (found in dm-dirty-log.h):
* int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
* unsigned argc, char **argv);
*
* Payload-to-userspace:
* A single string containing all the argv arguments separated by ' 's
* Payload-to-kernel:
* A NUL-terminated string that is the name of the device that is used
* as the backing store for the log data. 'dm_get_device' will be called
* on this device. ('dm_put_device' will be called on this device
* automatically after calling DM_ULOG_DTR.) If there is no device needed
* for log data, 'data_size' in the dm_ulog_request struct should be 0.
*
* The UUID contained in the dm_ulog_request structure is the reference that
* will be used by all request types to a specific log. The constructor must
* record this association with the instance created.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field, filling the
* data field with the log device if necessary, and setting 'data_size'
* appropriately.
*/
#define DM_ULOG_CTR 1
/*
* DM_ULOG_DTR corresponds to (found in dm-dirty-log.h):
* void (*dtr)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* A single string containing all the argv arguments separated by ' 's
* Payload-to-kernel:
* None. ('data_size' in the dm_ulog_request struct should be 0.)
*
* The UUID contained in the dm_ulog_request structure is all that is
* necessary to identify the log instance being destroyed. There is no
* payload data.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and clearing
* 'data_size' appropriately.
*/
#define DM_ULOG_DTR 2
/*
* DM_ULOG_PRESUSPEND corresponds to (found in dm-dirty-log.h):
* int (*presuspend)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* None.
*
* The UUID contained in the dm_ulog_request structure is all that is
* necessary to identify the log instance being presuspended. There is no
* payload data.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and
* 'data_size' appropriately.
*/
#define DM_ULOG_PRESUSPEND 3
/*
* DM_ULOG_POSTSUSPEND corresponds to (found in dm-dirty-log.h):
* int (*postsuspend)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* None.
*
* The UUID contained in the dm_ulog_request structure is all that is
* necessary to identify the log instance being postsuspended. There is no
* payload data.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and
* 'data_size' appropriately.
*/
#define DM_ULOG_POSTSUSPEND 4
/*
* DM_ULOG_RESUME corresponds to (found in dm-dirty-log.h):
* int (*resume)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* None.
*
* The UUID contained in the dm_ulog_request structure is all that is
* necessary to identify the log instance being resumed. There is no
* payload data.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and
* 'data_size' appropriately.
*/
#define DM_ULOG_RESUME 5
/*
* DM_ULOG_GET_REGION_SIZE corresponds to (found in dm-dirty-log.h):
* uint32_t (*get_region_size)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* uint64_t - contains the region size
*
* The region size is something that was determined at constructor time.
* It is returned in the payload area and 'data_size' is set to
* reflect this.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field appropriately.
*/
#define DM_ULOG_GET_REGION_SIZE 6
/*
* DM_ULOG_IS_CLEAN corresponds to (found in dm-dirty-log.h):
* int (*is_clean)(struct dm_dirty_log *log, region_t region);
*
* Payload-to-userspace:
* uint64_t - the region to get clean status on
* Payload-to-kernel:
* int64_t - 1 if clean, 0 otherwise
*
* Payload is sizeof(uint64_t) and contains the region for which the clean
* status is being made.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - filling the payload with 0 (not clean) or
* 1 (clean), setting 'data_size' and 'error' appropriately.
*/
#define DM_ULOG_IS_CLEAN 7
/*
* DM_ULOG_IN_SYNC corresponds to (found in dm-dirty-log.h):
* int (*in_sync)(struct dm_dirty_log *log, region_t region,
* int can_block);
*
* Payload-to-userspace:
* uint64_t - the region to get sync status on
* Payload-to-kernel:
* int64_t - 1 if in-sync, 0 otherwise
*
* Exactly the same as 'is_clean' above, except this time asking "has the
* region been recovered?" vs. "is the region not being modified?"
*/
#define DM_ULOG_IN_SYNC 8
/*
* DM_ULOG_FLUSH corresponds to (found in dm-dirty-log.h):
* int (*flush)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* None.
*
* No incoming or outgoing payload. Simply flush log state to disk.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and clearing
* 'data_size' appropriately.
*/
#define DM_ULOG_FLUSH 9
/*
* DM_ULOG_MARK_REGION corresponds to (found in dm-dirty-log.h):
* void (*mark_region)(struct dm_dirty_log *log, region_t region);
*
* Payload-to-userspace:
* uint64_t [] - region(s) to mark
* Payload-to-kernel:
* None.
*
* Incoming payload contains the one or more regions to mark dirty.
* The number of regions contained in the payload can be determined from
* 'data_size/sizeof(uint64_t)'.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and clearing
* 'data_size' appropriately.
*/
#define DM_ULOG_MARK_REGION 10
/*
* DM_ULOG_CLEAR_REGION corresponds to (found in dm-dirty-log.h):
* void (*clear_region)(struct dm_dirty_log *log, region_t region);
*
* Payload-to-userspace:
* uint64_t [] - region(s) to clear
* Payload-to-kernel:
* None.
*
* Incoming payload contains the one or more regions to mark clean.
* The number of regions contained in the payload can be determined from
* 'data_size/sizeof(uint64_t)'.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and clearing
* 'data_size' appropriately.
*/
#define DM_ULOG_CLEAR_REGION 11
/*
* DM_ULOG_GET_RESYNC_WORK corresponds to (found in dm-dirty-log.h):
* int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* {
* int64_t i; -- 1 if recovery necessary, 0 otherwise
* uint64_t r; -- The region to recover if i=1
* }
* 'data_size' should be set appropriately.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field appropriately.
*/
#define DM_ULOG_GET_RESYNC_WORK 12
/*
* DM_ULOG_SET_REGION_SYNC corresponds to (found in dm-dirty-log.h):
* void (*set_region_sync)(struct dm_dirty_log *log,
* region_t region, int in_sync);
*
* Payload-to-userspace:
* {
* uint64_t - region to set sync state on
* int64_t - 0 if not-in-sync, 1 if in-sync
* }
* Payload-to-kernel:
* None.
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and clearing
* 'data_size' appropriately.
*/
#define DM_ULOG_SET_REGION_SYNC 13
/*
* DM_ULOG_GET_SYNC_COUNT corresponds to (found in dm-dirty-log.h):
* region_t (*get_sync_count)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* uint64_t - the number of in-sync regions
*
* No incoming payload. Kernel-bound payload contains the number of
* regions that are in-sync (in a size_t).
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and
* 'data_size' appropriately.
*/
#define DM_ULOG_GET_SYNC_COUNT 14
/*
* DM_ULOG_STATUS_INFO corresponds to (found in dm-dirty-log.h):
* int (*status)(struct dm_dirty_log *log, STATUSTYPE_INFO,
* char *result, unsigned maxlen);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* Character string containing STATUSTYPE_INFO
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and
* 'data_size' appropriately.
*/
#define DM_ULOG_STATUS_INFO 15
/*
* DM_ULOG_STATUS_TABLE corresponds to (found in dm-dirty-log.h):
* int (*status)(struct dm_dirty_log *log, STATUSTYPE_TABLE,
* char *result, unsigned maxlen);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* Character string containing STATUSTYPE_TABLE
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and
* 'data_size' appropriately.
*/
#define DM_ULOG_STATUS_TABLE 16
/*
* DM_ULOG_IS_REMOTE_RECOVERING corresponds to (found in dm-dirty-log.h):
* int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
*
* Payload-to-userspace:
* uint64_t - region to determine recovery status on
* Payload-to-kernel:
* {
* int64_t is_recovering; -- 0 if no, 1 if yes
* uint64_t in_sync_hint; -- lowest region still needing resync
* }
*
* When the request has been processed, user-space must return the
* dm_ulog_request to the kernel - setting the 'error' field and
* 'data_size' appropriately.
*/
#define DM_ULOG_IS_REMOTE_RECOVERING 17
/*
* (DM_ULOG_REQUEST_MASK & request_type) to get the request type
*
* Payload-to-userspace:
* A single string containing all the argv arguments separated by ' 's
* Payload-to-kernel:
* None. ('data_size' in the dm_ulog_request struct should be 0.)
*
* We are reserving 8 bits of the 32-bit 'request_type' field for the
* various request types above. The remaining 24-bits are currently
* set to zero and are reserved for future use and compatibility concerns.
*
* User-space should always use DM_ULOG_REQUEST_TYPE to acquire the
* request type from the 'request_type' field to maintain forward compatibility.
*/
#define DM_ULOG_REQUEST_MASK 0xFF
#define DM_ULOG_REQUEST_TYPE(request_type) \
(DM_ULOG_REQUEST_MASK & (request_type))
/*
* DM_ULOG_REQUEST_VERSION is incremented when there is a
* change to the way information is passed between kernel
* and userspace. This could be a structure change of
* dm_ulog_request or a change in the way requests are
* issued/handled. Changes are outlined here:
* version 1: Initial implementation
* version 2: DM_ULOG_CTR allowed to return a string containing a
* device name that is to be registered with DM via
* 'dm_get_device'.
*/
#define DM_ULOG_REQUEST_VERSION 2
struct dm_ulog_request {
/*
* The local unique identifier (luid) and the universally unique
* identifier (uuid) are used to tie a request to a specific
* mirror log. A single machine log could probably make due with
* just the 'luid', but a cluster-aware log must use the 'uuid' and
* the 'luid'. The uuid is what is required for node to node
* communication concerning a particular log, but the 'luid' helps
* differentiate between logs that are being swapped and have the
* same 'uuid'. (Think "live" and "inactive" device-mapper tables.)
*/
uint64_t luid;
char uuid[DM_UUID_LEN];
char padding[3]; /* Padding because DM_UUID_LEN = 129 */
uint32_t version; /* See DM_ULOG_REQUEST_VERSION */
int32_t error; /* Used to report back processing errors */
uint32_t seq; /* Sequence number for request */
uint32_t request_type; /* DM_ULOG_* defined above */
uint32_t data_size; /* How much data (not including this struct) */
char data[0];
};
#endif /* __DM_LOG_USERSPACE_H__ */
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