Current File : //usr/include/linux/dm-log-userspace.h
/* SPDX-License-Identifier: LGPL-2.0+ WITH Linux-syscall-note */
/*
* 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/types.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):
* __u32 (*get_region_size)(struct dm_dirty_log *log);
*
* Payload-to-userspace:
* None.
* Payload-to-kernel:
* __u64 - 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:
* __u64 - the region to get clean status on
* Payload-to-kernel:
* __s64 - 1 if clean, 0 otherwise
*
* Payload is sizeof(__u64) 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:
* __u64 - the region to get sync status on
* Payload-to-kernel:
* __s64 - 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:
* If the 'integrated_flush' directive is present in the constructor
* table, the payload is as same as DM_ULOG_MARK_REGION:
* __u64 [] - region(s) to mark
* else
* None
* Payload-to-kernel:
* None.
*
* If the 'integrated_flush' option was used during the creation of the
* log, mark region requests are carried as payload in the flush request.
* Piggybacking the mark requests in this way allows for fewer communications
* between kernel and userspace.
*
* 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:
* __u64 [] - 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(__u64)'.
*
* 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:
* __u64 [] - 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(__u64)'.
*
* 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:
* {
* __s64 i; -- 1 if recovery necessary, 0 otherwise
* __u64 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:
* {
* __u64 - region to set sync state on
* __s64 - 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:
* __u64 - 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:
* __u64 - region to determine recovery status on
* Payload-to-kernel:
* {
* __s64 is_recovering; -- 0 if no, 1 if yes
* __u64 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'.
* version 3: DM_ULOG_FLUSH is capable of carrying payload for marking
* regions. This "integrated flush" reduces the number of
* requests between the kernel and userspace by effectively
* merging 'mark' and 'flush' requests. A constructor table
* argument ('integrated_flush') is required to turn this
* feature on, so it is backwards compatible with older
* userspace versions.
*/
#define DM_ULOG_REQUEST_VERSION 3
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.)
*/
__u64 luid;
char uuid[DM_UUID_LEN];
char padding[3]; /* Padding because DM_UUID_LEN = 129 */
__u32 version; /* See DM_ULOG_REQUEST_VERSION */
__s32 error; /* Used to report back processing errors */
__u32 seq; /* Sequence number for request */
__u32 request_type; /* DM_ULOG_* defined above */
__u32 data_size; /* How much data (not including this struct) */
char data[0];
};
#endif /* __DM_LOG_USERSPACE_H__ */
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