name : 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__ */