text: /*
   * 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__ */
  