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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /include/uapi/linux/dm-log-userspace.h
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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:
+ * If the 'integrated_flush' directive is present in the constructor
+ * table, the payload is as same as DM_ULOG_MARK_REGION:
+ * uint64_t [] - 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:
+ * 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'.
+ * 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.)
+ */
+ 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__ */