drbd: move UAPI headers to include/uapi/linux/

drbd.h and drbd_limits.h contain only type definitions, enums, and
constants shared between kernel and userspace. These should be part of
UAPI.

Split the genl_api header into two: the genlmsghdr and the enums are
UAPI, the rest stays there for now (it will be removed by one of the
next commits in this series).

drbd_config.h is clearly DRBD-internal, so move it there.

Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20260506124541.1951772-2-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 683 insertions, 0 deletions

diff --git a/include/uapi/linux/drbd.h b/include/uapi/linux/drbd.h
new file mode 100644
index 000000000000..7930a972d8a4
--- /dev/null
+++ b/include/uapi/linux/drbd.h
@@ -0,0 +1,432 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later WITH Linux-syscall-note */
+/*
+  drbd.h
+  Kernel module for 2.6.x Kernels
+
+  This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
+
+  Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
+  Copyright (C) 2001-2008, Philipp Reisner <philipp.reisner@linbit.com>.
+  Copyright (C) 2001-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
+
+
+*/
+#ifndef DRBD_H
+#define DRBD_H
+#include <asm/types.h>
+
+#ifdef __KERNEL__
+#include <linux/types.h>
+#include <asm/byteorder.h>
+#else
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <limits.h>
+
+/* Although the Linux source code makes a difference between
+   generic endianness and the bitfields' endianness, there is no
+   architecture as of Linux-2.6.24-rc4 where the bitfields' endianness
+   does not match the generic endianness. */
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define __LITTLE_ENDIAN_BITFIELD
+#elif __BYTE_ORDER == __BIG_ENDIAN
+#define __BIG_ENDIAN_BITFIELD
+#else
+# error "sorry, weird endianness on this box"
+#endif
+
+#endif
+
+enum drbd_io_error_p {
+	EP_PASS_ON, /* FIXME should the better be named "Ignore"? */
+	EP_CALL_HELPER,
+	EP_DETACH
+};
+
+enum drbd_fencing_p {
+	FP_NOT_AVAIL = -1, /* Not a policy */
+	FP_DONT_CARE = 0,
+	FP_RESOURCE,
+	FP_STONITH
+};
+
+enum drbd_disconnect_p {
+	DP_RECONNECT,
+	DP_DROP_NET_CONF,
+	DP_FREEZE_IO
+};
+
+enum drbd_after_sb_p {
+	ASB_DISCONNECT,
+	ASB_DISCARD_YOUNGER_PRI,
+	ASB_DISCARD_OLDER_PRI,
+	ASB_DISCARD_ZERO_CHG,
+	ASB_DISCARD_LEAST_CHG,
+	ASB_DISCARD_LOCAL,
+	ASB_DISCARD_REMOTE,
+	ASB_CONSENSUS,
+	ASB_DISCARD_SECONDARY,
+	ASB_CALL_HELPER,
+	ASB_VIOLENTLY
+};
+
+enum drbd_on_no_data {
+	OND_IO_ERROR,
+	OND_SUSPEND_IO
+};
+
+enum drbd_on_congestion {
+	OC_BLOCK,
+	OC_PULL_AHEAD,
+	OC_DISCONNECT,
+};
+
+enum drbd_read_balancing {
+	RB_PREFER_LOCAL,
+	RB_PREFER_REMOTE,
+	RB_ROUND_ROBIN,
+	RB_LEAST_PENDING,
+	RB_CONGESTED_REMOTE,
+	RB_32K_STRIPING,
+	RB_64K_STRIPING,
+	RB_128K_STRIPING,
+	RB_256K_STRIPING,
+	RB_512K_STRIPING,
+	RB_1M_STRIPING,
+};
+
+/* KEEP the order, do not delete or insert. Only append. */
+enum drbd_ret_code {
+	ERR_CODE_BASE		= 100,
+	NO_ERROR		= 101,
+	ERR_LOCAL_ADDR		= 102,
+	ERR_PEER_ADDR		= 103,
+	ERR_OPEN_DISK		= 104,
+	ERR_OPEN_MD_DISK	= 105,
+	ERR_DISK_NOT_BDEV	= 107,
+	ERR_MD_NOT_BDEV		= 108,
+	ERR_DISK_TOO_SMALL	= 111,
+	ERR_MD_DISK_TOO_SMALL	= 112,
+	ERR_BDCLAIM_DISK	= 114,
+	ERR_BDCLAIM_MD_DISK	= 115,
+	ERR_MD_IDX_INVALID	= 116,
+	ERR_IO_MD_DISK		= 118,
+	ERR_MD_INVALID          = 119,
+	ERR_AUTH_ALG		= 120,
+	ERR_AUTH_ALG_ND		= 121,
+	ERR_NOMEM		= 122,
+	ERR_DISCARD_IMPOSSIBLE	= 123,
+	ERR_DISK_CONFIGURED	= 124,
+	ERR_NET_CONFIGURED	= 125,
+	ERR_MANDATORY_TAG	= 126,
+	ERR_MINOR_INVALID	= 127,
+	ERR_INTR		= 129, /* EINTR */
+	ERR_RESIZE_RESYNC	= 130,
+	ERR_NO_PRIMARY		= 131,
+	ERR_RESYNC_AFTER	= 132,
+	ERR_RESYNC_AFTER_CYCLE	= 133,
+	ERR_PAUSE_IS_SET	= 134,
+	ERR_PAUSE_IS_CLEAR	= 135,
+	ERR_PACKET_NR		= 137,
+	ERR_NO_DISK		= 138,
+	ERR_NOT_PROTO_C		= 139,
+	ERR_NOMEM_BITMAP	= 140,
+	ERR_INTEGRITY_ALG	= 141, /* DRBD 8.2 only */
+	ERR_INTEGRITY_ALG_ND	= 142, /* DRBD 8.2 only */
+	ERR_CPU_MASK_PARSE	= 143, /* DRBD 8.2 only */
+	ERR_CSUMS_ALG		= 144, /* DRBD 8.2 only */
+	ERR_CSUMS_ALG_ND	= 145, /* DRBD 8.2 only */
+	ERR_VERIFY_ALG		= 146, /* DRBD 8.2 only */
+	ERR_VERIFY_ALG_ND	= 147, /* DRBD 8.2 only */
+	ERR_CSUMS_RESYNC_RUNNING= 148, /* DRBD 8.2 only */
+	ERR_VERIFY_RUNNING	= 149, /* DRBD 8.2 only */
+	ERR_DATA_NOT_CURRENT	= 150,
+	ERR_CONNECTED		= 151, /* DRBD 8.3 only */
+	ERR_PERM		= 152,
+	ERR_NEED_APV_93		= 153,
+	ERR_STONITH_AND_PROT_A  = 154,
+	ERR_CONG_NOT_PROTO_A	= 155,
+	ERR_PIC_AFTER_DEP	= 156,
+	ERR_PIC_PEER_DEP	= 157,
+	ERR_RES_NOT_KNOWN	= 158,
+	ERR_RES_IN_USE		= 159,
+	ERR_MINOR_CONFIGURED    = 160,
+	ERR_MINOR_OR_VOLUME_EXISTS = 161,
+	ERR_INVALID_REQUEST	= 162,
+	ERR_NEED_APV_100	= 163,
+	ERR_NEED_ALLOW_TWO_PRI  = 164,
+	ERR_MD_UNCLEAN          = 165,
+	ERR_MD_LAYOUT_CONNECTED = 166,
+	ERR_MD_LAYOUT_TOO_BIG   = 167,
+	ERR_MD_LAYOUT_TOO_SMALL = 168,
+	ERR_MD_LAYOUT_NO_FIT    = 169,
+	ERR_IMPLICIT_SHRINK     = 170,
+	/* insert new ones above this line */
+	AFTER_LAST_ERR_CODE
+};
+
+#define DRBD_PROT_A   1
+#define DRBD_PROT_B   2
+#define DRBD_PROT_C   3
+
+enum drbd_role {
+	R_UNKNOWN = 0,
+	R_PRIMARY = 1,     /* role */
+	R_SECONDARY = 2,   /* role */
+	R_MASK = 3,
+};
+
+/* The order of these constants is important.
+ * The lower ones (<C_WF_REPORT_PARAMS) indicate
+ * that there is no socket!
+ * >=C_WF_REPORT_PARAMS ==> There is a socket
+ */
+enum drbd_conns {
+	C_STANDALONE,
+	C_DISCONNECTING,  /* Temporal state on the way to StandAlone. */
+	C_UNCONNECTED,    /* >= C_UNCONNECTED -> inc_net() succeeds */
+
+	/* These temporal states are all used on the way
+	 * from >= C_CONNECTED to Unconnected.
+	 * The 'disconnect reason' states
+	 * I do not allow to change between them. */
+	C_TIMEOUT,
+	C_BROKEN_PIPE,
+	C_NETWORK_FAILURE,
+	C_PROTOCOL_ERROR,
+	C_TEAR_DOWN,
+
+	C_WF_CONNECTION,
+	C_WF_REPORT_PARAMS, /* we have a socket */
+	C_CONNECTED,      /* we have introduced each other */
+	C_STARTING_SYNC_S,  /* starting full sync by admin request. */
+	C_STARTING_SYNC_T,  /* starting full sync by admin request. */
+	C_WF_BITMAP_S,
+	C_WF_BITMAP_T,
+	C_WF_SYNC_UUID,
+
+	/* All SyncStates are tested with this comparison
+	 * xx >= C_SYNC_SOURCE && xx <= C_PAUSED_SYNC_T */
+	C_SYNC_SOURCE,
+	C_SYNC_TARGET,
+	C_VERIFY_S,
+	C_VERIFY_T,
+	C_PAUSED_SYNC_S,
+	C_PAUSED_SYNC_T,
+
+	C_AHEAD,
+	C_BEHIND,
+
+	C_MASK = 31
+};
+
+enum drbd_disk_state {
+	D_DISKLESS,
+	D_ATTACHING,      /* In the process of reading the meta-data */
+	D_FAILED,         /* Becomes D_DISKLESS as soon as we told it the peer */
+			  /* when >= D_FAILED it is legal to access mdev->ldev */
+	D_NEGOTIATING,    /* Late attaching state, we need to talk to the peer */
+	D_INCONSISTENT,
+	D_OUTDATED,
+	D_UNKNOWN,       /* Only used for the peer, never for myself */
+	D_CONSISTENT,     /* Might be D_OUTDATED, might be D_UP_TO_DATE ... */
+	D_UP_TO_DATE,       /* Only this disk state allows applications' IO ! */
+	D_MASK = 15
+};
+
+union drbd_state {
+/* According to gcc's docs is the ...
+ * The order of allocation of bit-fields within a unit (C90 6.5.2.1, C99 6.7.2.1).
+ * Determined by ABI.
+ * pointed out by Maxim Uvarov q<muvarov@ru.mvista.com>
+ * even though we transmit as "cpu_to_be32(state)",
+ * the offsets of the bitfields still need to be swapped
+ * on different endianness.
+ */
+	struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+		unsigned role:2 ;   /* 3/4	 primary/secondary/unknown */
+		unsigned peer:2 ;   /* 3/4	 primary/secondary/unknown */
+		unsigned conn:5 ;   /* 17/32	 cstates */
+		unsigned disk:4 ;   /* 8/16	 from D_DISKLESS to D_UP_TO_DATE */
+		unsigned pdsk:4 ;   /* 8/16	 from D_DISKLESS to D_UP_TO_DATE */
+		unsigned susp:1 ;   /* 2/2	 IO suspended no/yes (by user) */
+		unsigned aftr_isp:1 ; /* isp .. imposed sync pause */
+		unsigned peer_isp:1 ;
+		unsigned user_isp:1 ;
+		unsigned susp_nod:1 ; /* IO suspended because no data */
+		unsigned susp_fen:1 ; /* IO suspended because fence peer handler runs*/
+		unsigned _pad:9;   /* 0	 unused */
+#elif defined(__BIG_ENDIAN_BITFIELD)
+		unsigned _pad:9;
+		unsigned susp_fen:1 ;
+		unsigned susp_nod:1 ;
+		unsigned user_isp:1 ;
+		unsigned peer_isp:1 ;
+		unsigned aftr_isp:1 ; /* isp .. imposed sync pause */
+		unsigned susp:1 ;   /* 2/2	 IO suspended  no/yes */
+		unsigned pdsk:4 ;   /* 8/16	 from D_DISKLESS to D_UP_TO_DATE */
+		unsigned disk:4 ;   /* 8/16	 from D_DISKLESS to D_UP_TO_DATE */
+		unsigned conn:5 ;   /* 17/32	 cstates */
+		unsigned peer:2 ;   /* 3/4	 primary/secondary/unknown */
+		unsigned role:2 ;   /* 3/4	 primary/secondary/unknown */
+#else
+# error "this endianness is not supported"
+#endif
+	};
+	unsigned int i;
+};
+
+enum drbd_state_rv {
+	SS_CW_NO_NEED = 4,
+	SS_CW_SUCCESS = 3,
+	SS_NOTHING_TO_DO = 2,
+	SS_SUCCESS = 1,
+	SS_UNKNOWN_ERROR = 0, /* Used to sleep longer in _drbd_request_state */
+	SS_TWO_PRIMARIES = -1,
+	SS_NO_UP_TO_DATE_DISK = -2,
+	SS_NO_LOCAL_DISK = -4,
+	SS_NO_REMOTE_DISK = -5,
+	SS_CONNECTED_OUTDATES = -6,
+	SS_PRIMARY_NOP = -7,
+	SS_RESYNC_RUNNING = -8,
+	SS_ALREADY_STANDALONE = -9,
+	SS_CW_FAILED_BY_PEER = -10,
+	SS_IS_DISKLESS = -11,
+	SS_DEVICE_IN_USE = -12,
+	SS_NO_NET_CONFIG = -13,
+	SS_NO_VERIFY_ALG = -14,       /* drbd-8.2 only */
+	SS_NEED_CONNECTION = -15,    /* drbd-8.2 only */
+	SS_LOWER_THAN_OUTDATED = -16,
+	SS_NOT_SUPPORTED = -17,      /* drbd-8.2 only */
+	SS_IN_TRANSIENT_STATE = -18,  /* Retry after the next state change */
+	SS_CONCURRENT_ST_CHG = -19,   /* Concurrent cluster side state change! */
+	SS_O_VOL_PEER_PRI = -20,
+	SS_OUTDATE_WO_CONN = -21,
+	SS_AFTER_LAST_ERROR = -22,    /* Keep this at bottom */
+};
+
+#define SHARED_SECRET_MAX 64
+
+#define MDF_CONSISTENT		(1 << 0)
+#define MDF_PRIMARY_IND		(1 << 1)
+#define MDF_CONNECTED_IND	(1 << 2)
+#define MDF_FULL_SYNC		(1 << 3)
+#define MDF_WAS_UP_TO_DATE	(1 << 4)
+#define MDF_PEER_OUT_DATED	(1 << 5)
+#define MDF_CRASHED_PRIMARY	(1 << 6)
+#define MDF_AL_CLEAN		(1 << 7)
+#define MDF_AL_DISABLED		(1 << 8)
+
+#define MAX_PEERS 32
+
+enum drbd_uuid_index {
+	UI_CURRENT,
+	UI_BITMAP,
+	UI_HISTORY_START,
+	UI_HISTORY_END,
+	UI_SIZE,      /* nl-packet: number of dirty bits */
+	UI_FLAGS,     /* nl-packet: flags */
+	UI_EXTENDED_SIZE   /* Everything. */
+};
+
+#define HISTORY_UUIDS MAX_PEERS
+
+enum drbd_timeout_flag {
+	UT_DEFAULT      = 0,
+	UT_DEGRADED     = 1,
+	UT_PEER_OUTDATED = 2,
+};
+
+enum drbd_notification_type {
+	NOTIFY_EXISTS,
+	NOTIFY_CREATE,
+	NOTIFY_CHANGE,
+	NOTIFY_DESTROY,
+	NOTIFY_CALL,
+	NOTIFY_RESPONSE,
+
+	NOTIFY_CONTINUES = 0x8000,
+	NOTIFY_FLAGS = NOTIFY_CONTINUES,
+};
+
+enum drbd_peer_state {
+	P_INCONSISTENT = 3,
+	P_OUTDATED = 4,
+	P_DOWN = 5,
+	P_PRIMARY = 6,
+	P_FENCING = 7,
+};
+
+#define UUID_JUST_CREATED ((__u64)4)
+
+enum write_ordering_e {
+	WO_NONE,
+	WO_DRAIN_IO,
+	WO_BDEV_FLUSH,
+	WO_BIO_BARRIER
+};
+
+/* magic numbers used in meta data and network packets */
+#define DRBD_MAGIC 0x83740267
+#define DRBD_MAGIC_BIG 0x835a
+#define DRBD_MAGIC_100 0x8620ec20
+
+#define DRBD_MD_MAGIC_07   (DRBD_MAGIC+3)
+#define DRBD_MD_MAGIC_08   (DRBD_MAGIC+4)
+#define DRBD_MD_MAGIC_84_UNCLEAN	(DRBD_MAGIC+5)
+
+
+/* how I came up with this magic?
+ * base64 decode "actlog==" ;) */
+#define DRBD_AL_MAGIC 0x69cb65a2
+
+/* these are of type "int" */
+#define DRBD_MD_INDEX_INTERNAL -1
+#define DRBD_MD_INDEX_FLEX_EXT -2
+#define DRBD_MD_INDEX_FLEX_INT -3
+
+#define DRBD_CPU_MASK_SIZE 32
+
+/**
+ * struct drbd_genlmsghdr - DRBD specific header used in NETLINK_GENERIC requests
+ * @minor:
+ *     For admin requests (user -> kernel): which minor device to operate on.
+ *     For (unicast) replies or informational (broadcast) messages
+ *     (kernel -> user): which minor device the information is about.
+ *     If we do not operate on minors, but on connections or resources,
+ *     the minor value shall be (~0), and the attribute DRBD_NLA_CFG_CONTEXT
+ *     is used instead.
+ * @flags: possible operation modifiers (relevant only for user->kernel):
+ *     DRBD_GENL_F_SET_DEFAULTS
+ * @volume:
+ *     When creating a new minor (adding it to a resource), the resource needs
+ *     to know which volume number within the resource this is supposed to be.
+ *     The volume number corresponds to the same volume number on the remote side,
+ *     whereas the minor number on the remote side may be different
+ *     (union with flags).
+ * @ret_code: kernel->userland unicast cfg reply return code (union with flags);
+ */
+struct drbd_genlmsghdr {
+	__u32 minor;
+	union {
+		__u32 flags;
+		__s32 ret_code;
+	};
+};
+
+/* To be used in drbd_genlmsghdr.flags */
+enum {
+	DRBD_GENL_F_SET_DEFAULTS = 1,
+};
+
+enum drbd_state_info_bcast_reason {
+	SIB_GET_STATUS_REPLY = 1,
+	SIB_STATE_CHANGE = 2,
+	SIB_HELPER_PRE = 3,
+	SIB_HELPER_POST = 4,
+	SIB_SYNC_PROGRESS = 5,
+};
+
+#endif
diff --git a/include/uapi/linux/drbd_limits.h b/include/uapi/linux/drbd_limits.h
new file mode 100644
index 000000000000..a72a102d1ca7
--- /dev/null
+++ b/include/uapi/linux/drbd_limits.h
@@ -0,0 +1,251 @@
+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/*
+  drbd_limits.h
+  This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
+*/
+
+/*
+ * Our current limitations.
+ * Some of them are hard limits,
+ * some of them are arbitrary range limits, that make it easier to provide
+ * feedback about nonsense settings for certain configurable values.
+ */
+
+#ifndef DRBD_LIMITS_H
+#define DRBD_LIMITS_H 1
+
+#define DEBUG_RANGE_CHECK 0
+
+#define DRBD_MINOR_COUNT_MIN 1U
+#define DRBD_MINOR_COUNT_MAX 255U
+#define DRBD_MINOR_COUNT_DEF 32U
+#define DRBD_MINOR_COUNT_SCALE '1'
+
+#define DRBD_VOLUME_MAX 65534U
+
+#define DRBD_DIALOG_REFRESH_MIN 0U
+#define DRBD_DIALOG_REFRESH_MAX 600U
+#define DRBD_DIALOG_REFRESH_SCALE '1'
+
+/* valid port number */
+#define DRBD_PORT_MIN 1U
+#define DRBD_PORT_MAX 0xffffU
+#define DRBD_PORT_SCALE '1'
+
+/* startup { */
+  /* if you want more than 3.4 days, disable */
+#define DRBD_WFC_TIMEOUT_MIN 0U
+#define DRBD_WFC_TIMEOUT_MAX 300000U
+#define DRBD_WFC_TIMEOUT_DEF 0U
+#define DRBD_WFC_TIMEOUT_SCALE '1'
+
+#define DRBD_DEGR_WFC_TIMEOUT_MIN 0U
+#define DRBD_DEGR_WFC_TIMEOUT_MAX 300000U
+#define DRBD_DEGR_WFC_TIMEOUT_DEF 0U
+#define DRBD_DEGR_WFC_TIMEOUT_SCALE '1'
+
+#define DRBD_OUTDATED_WFC_TIMEOUT_MIN 0U
+#define DRBD_OUTDATED_WFC_TIMEOUT_MAX 300000U
+#define DRBD_OUTDATED_WFC_TIMEOUT_DEF 0U
+#define DRBD_OUTDATED_WFC_TIMEOUT_SCALE '1'
+/* }*/
+
+/* net { */
+  /* timeout, unit centi seconds
+   * more than one minute timeout is not useful */
+#define DRBD_TIMEOUT_MIN 1U
+#define DRBD_TIMEOUT_MAX 600U
+#define DRBD_TIMEOUT_DEF 60U       /* 6 seconds */
+#define DRBD_TIMEOUT_SCALE '1'
+
+ /* If backing disk takes longer than disk_timeout, mark the disk as failed */
+#define DRBD_DISK_TIMEOUT_MIN 0U    /* 0 = disabled */
+#define DRBD_DISK_TIMEOUT_MAX 6000U /* 10 Minutes */
+#define DRBD_DISK_TIMEOUT_DEF 0U    /* disabled */
+#define DRBD_DISK_TIMEOUT_SCALE '1'
+
+  /* active connection retries when C_WF_CONNECTION */
+#define DRBD_CONNECT_INT_MIN 1U
+#define DRBD_CONNECT_INT_MAX 120U
+#define DRBD_CONNECT_INT_DEF 10U   /* seconds */
+#define DRBD_CONNECT_INT_SCALE '1'
+
+  /* keep-alive probes when idle */
+#define DRBD_PING_INT_MIN 1U
+#define DRBD_PING_INT_MAX 120U
+#define DRBD_PING_INT_DEF 10U
+#define DRBD_PING_INT_SCALE '1'
+
+ /* timeout for the ping packets.*/
+#define DRBD_PING_TIMEO_MIN  1U
+#define DRBD_PING_TIMEO_MAX  300U
+#define DRBD_PING_TIMEO_DEF  5U
+#define DRBD_PING_TIMEO_SCALE '1'
+
+  /* max number of write requests between write barriers */
+#define DRBD_MAX_EPOCH_SIZE_MIN 1U
+#define DRBD_MAX_EPOCH_SIZE_MAX 20000U
+#define DRBD_MAX_EPOCH_SIZE_DEF 2048U
+#define DRBD_MAX_EPOCH_SIZE_SCALE '1'
+
+  /* I don't think that a tcp send buffer of more than 10M is useful */
+#define DRBD_SNDBUF_SIZE_MIN  0U
+#define DRBD_SNDBUF_SIZE_MAX  (10U<<20)
+#define DRBD_SNDBUF_SIZE_DEF  0U
+#define DRBD_SNDBUF_SIZE_SCALE '1'
+
+#define DRBD_RCVBUF_SIZE_MIN  0U
+#define DRBD_RCVBUF_SIZE_MAX  (10U<<20)
+#define DRBD_RCVBUF_SIZE_DEF  0U
+#define DRBD_RCVBUF_SIZE_SCALE '1'
+
+  /* @4k PageSize -> 128kB - 512MB */
+#define DRBD_MAX_BUFFERS_MIN  32U
+#define DRBD_MAX_BUFFERS_MAX  131072U
+#define DRBD_MAX_BUFFERS_DEF  2048U
+#define DRBD_MAX_BUFFERS_SCALE '1'
+
+  /* @4k PageSize -> 4kB - 512MB */
+#define DRBD_UNPLUG_WATERMARK_MIN  1U
+#define DRBD_UNPLUG_WATERMARK_MAX  131072U
+#define DRBD_UNPLUG_WATERMARK_DEF (DRBD_MAX_BUFFERS_DEF/16)
+#define DRBD_UNPLUG_WATERMARK_SCALE '1'
+
+  /* 0 is disabled.
+   * 200 should be more than enough even for very short timeouts */
+#define DRBD_KO_COUNT_MIN  0U
+#define DRBD_KO_COUNT_MAX  200U
+#define DRBD_KO_COUNT_DEF  7U
+#define DRBD_KO_COUNT_SCALE '1'
+/* } */
+
+/* syncer { */
+  /* FIXME allow rate to be zero? */
+#define DRBD_RESYNC_RATE_MIN 1U
+/* channel bonding 10 GbE, or other hardware */
+#define DRBD_RESYNC_RATE_MAX (4 << 20)
+#define DRBD_RESYNC_RATE_DEF 250U
+#define DRBD_RESYNC_RATE_SCALE 'k'  /* kilobytes */
+
+#define DRBD_AL_EXTENTS_MIN  67U
+  /* we use u16 as "slot number", (u16)~0 is "FREE".
+   * If you use >= 292 kB on-disk ring buffer,
+   * this is the maximum you can use: */
+#define DRBD_AL_EXTENTS_MAX  0xfffeU
+#define DRBD_AL_EXTENTS_DEF  1237U
+#define DRBD_AL_EXTENTS_SCALE '1'
+
+#define DRBD_MINOR_NUMBER_MIN  -1
+#define DRBD_MINOR_NUMBER_MAX  ((1 << 20) - 1)
+#define DRBD_MINOR_NUMBER_DEF  -1
+#define DRBD_MINOR_NUMBER_SCALE '1'
+
+/* } */
+
+/* drbdsetup XY resize -d Z
+ * you are free to reduce the device size to nothing, if you want to.
+ * the upper limit with 64bit kernel, enough ram and flexible meta data
+ * is 1 PiB, currently. */
+/* DRBD_MAX_SECTORS */
+#define DRBD_DISK_SIZE_MIN  0LLU
+#define DRBD_DISK_SIZE_MAX  (1LLU * (2LLU << 40))
+#define DRBD_DISK_SIZE_DEF  0LLU /* = disabled = no user size... */
+#define DRBD_DISK_SIZE_SCALE 's'  /* sectors */
+
+#define DRBD_ON_IO_ERROR_DEF EP_DETACH
+#define DRBD_FENCING_DEF FP_DONT_CARE
+#define DRBD_AFTER_SB_0P_DEF ASB_DISCONNECT
+#define DRBD_AFTER_SB_1P_DEF ASB_DISCONNECT
+#define DRBD_AFTER_SB_2P_DEF ASB_DISCONNECT
+#define DRBD_RR_CONFLICT_DEF ASB_DISCONNECT
+#define DRBD_ON_NO_DATA_DEF OND_IO_ERROR
+#define DRBD_ON_CONGESTION_DEF OC_BLOCK
+#define DRBD_READ_BALANCING_DEF RB_PREFER_LOCAL
+
+#define DRBD_MAX_BIO_BVECS_MIN 0U
+#define DRBD_MAX_BIO_BVECS_MAX 128U
+#define DRBD_MAX_BIO_BVECS_DEF 0U
+#define DRBD_MAX_BIO_BVECS_SCALE '1'
+
+#define DRBD_C_PLAN_AHEAD_MIN  0U
+#define DRBD_C_PLAN_AHEAD_MAX  300U
+#define DRBD_C_PLAN_AHEAD_DEF  20U
+#define DRBD_C_PLAN_AHEAD_SCALE '1'
+
+#define DRBD_C_DELAY_TARGET_MIN 1U
+#define DRBD_C_DELAY_TARGET_MAX 100U
+#define DRBD_C_DELAY_TARGET_DEF 10U
+#define DRBD_C_DELAY_TARGET_SCALE '1'
+
+#define DRBD_C_FILL_TARGET_MIN 0U
+#define DRBD_C_FILL_TARGET_MAX (1U<<20) /* 500MByte in sec */
+#define DRBD_C_FILL_TARGET_DEF 100U /* Try to place 50KiB in socket send buffer during resync */
+#define DRBD_C_FILL_TARGET_SCALE 's'  /* sectors */
+
+#define DRBD_C_MAX_RATE_MIN     250U
+#define DRBD_C_MAX_RATE_MAX     (4U << 20)
+#define DRBD_C_MAX_RATE_DEF     102400U
+#define DRBD_C_MAX_RATE_SCALE	'k'  /* kilobytes */
+
+#define DRBD_C_MIN_RATE_MIN     0U
+#define DRBD_C_MIN_RATE_MAX     (4U << 20)
+#define DRBD_C_MIN_RATE_DEF     250U
+#define DRBD_C_MIN_RATE_SCALE	'k'  /* kilobytes */
+
+#define DRBD_CONG_FILL_MIN	0U
+#define DRBD_CONG_FILL_MAX	(10U<<21) /* 10GByte in sectors */
+#define DRBD_CONG_FILL_DEF	0U
+#define DRBD_CONG_FILL_SCALE	's'  /* sectors */
+
+#define DRBD_CONG_EXTENTS_MIN	DRBD_AL_EXTENTS_MIN
+#define DRBD_CONG_EXTENTS_MAX	DRBD_AL_EXTENTS_MAX
+#define DRBD_CONG_EXTENTS_DEF	DRBD_AL_EXTENTS_DEF
+#define DRBD_CONG_EXTENTS_SCALE DRBD_AL_EXTENTS_SCALE
+
+#define DRBD_PROTOCOL_DEF DRBD_PROT_C
+
+#define DRBD_DISK_BARRIER_DEF	0U
+#define DRBD_DISK_FLUSHES_DEF	1U
+#define DRBD_DISK_DRAIN_DEF	1U
+#define DRBD_MD_FLUSHES_DEF	1U
+#define DRBD_TCP_CORK_DEF	1U
+#define DRBD_AL_UPDATES_DEF     1U
+
+/* We used to ignore the discard_zeroes_data setting.
+ * To not change established (and expected) behaviour,
+ * by default assume that, for discard_zeroes_data=0,
+ * we can make that an effective discard_zeroes_data=1,
+ * if we only explicitly zero-out unaligned partial chunks. */
+#define DRBD_DISCARD_ZEROES_IF_ALIGNED_DEF 1U
+
+/* Some backends pretend to support WRITE SAME,
+ * but fail such requests when they are actually submitted.
+ * This is to tell DRBD to not even try. */
+#define DRBD_DISABLE_WRITE_SAME_DEF 0U
+
+#define DRBD_ALLOW_TWO_PRIMARIES_DEF	0U
+#define DRBD_ALWAYS_ASBP_DEF	0U
+#define DRBD_USE_RLE_DEF	1U
+#define DRBD_CSUMS_AFTER_CRASH_ONLY_DEF 0U
+
+#define DRBD_AL_STRIPES_MIN     1U
+#define DRBD_AL_STRIPES_MAX     1024U
+#define DRBD_AL_STRIPES_DEF     1U
+#define DRBD_AL_STRIPES_SCALE   '1'
+
+#define DRBD_AL_STRIPE_SIZE_MIN   4U
+#define DRBD_AL_STRIPE_SIZE_MAX   16777216U
+#define DRBD_AL_STRIPE_SIZE_DEF   32U
+#define DRBD_AL_STRIPE_SIZE_SCALE 'k' /* kilobytes */
+
+#define DRBD_SOCKET_CHECK_TIMEO_MIN 0U
+#define DRBD_SOCKET_CHECK_TIMEO_MAX DRBD_PING_TIMEO_MAX
+#define DRBD_SOCKET_CHECK_TIMEO_DEF 0U
+#define DRBD_SOCKET_CHECK_TIMEO_SCALE '1'
+
+#define DRBD_RS_DISCARD_GRANULARITY_MIN 0U
+#define DRBD_RS_DISCARD_GRANULARITY_MAX (1U<<20)  /* 1MiByte */
+#define DRBD_RS_DISCARD_GRANULARITY_DEF 0U     /* disabled by default */
+#define DRBD_RS_DISCARD_GRANULARITY_SCALE '1' /* bytes */
+
+#endif