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Diffstat (limited to 'include/linux/dm-log-userspace.h')
| -rw-r--r-- | include/linux/dm-log-userspace.h | 416 |
1 files changed, 416 insertions, 0 deletions
diff --git a/include/linux/dm-log-userspace.h b/include/linux/dm-log-userspace.h new file mode 100644 index 00000000..0678c2ad --- /dev/null +++ b/include/linux/dm-log-userspace.h @@ -0,0 +1,416 @@ +/* + * 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__ */ |