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    Subject[PATCH 07/16] DRBD: internal_data_structures
    Date
    The big "struct drbd_conf". It actually describes one DRBD device.

    Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
    Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

    ---
    diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
    new file mode 100644
    index 0000000..175de11
    --- /dev/null
    +++ b/drivers/block/drbd/drbd_int.h
    @@ -0,0 +1,2219 @@
    +/*
    + drbd_int.h
    +
    + This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
    +
    + Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
    + Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
    + Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
    +
    + drbd is free software; you can redistribute it and/or modify
    + it under the terms of the GNU General Public License as published by
    + the Free Software Foundation; either version 2, or (at your option)
    + any later version.
    +
    + drbd is distributed in the hope that it will be useful,
    + but WITHOUT ANY WARRANTY; without even the implied warranty of
    + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    + GNU General Public License for more details.
    +
    + You should have received a copy of the GNU General Public License
    + along with drbd; see the file COPYING. If not, write to
    + the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
    +
    +*/
    +
    +#ifndef _DRBD_INT_H
    +#define _DRBD_INT_H
    +
    +#include <linux/compiler.h>
    +#include <linux/types.h>
    +#include <linux/version.h>
    +#include <linux/list.h>
    +#include <linux/sched.h>
    +#include <linux/bitops.h>
    +#include <linux/slab.h>
    +#include <linux/crypto.h>
    +#include <linux/tcp.h>
    +#include <linux/mutex.h>
    +#include <linux/major.h>
    +#include <linux/blkdev.h>
    +#include <linux/bio.h>
    +#include <net/tcp.h>
    +#include "lru_cache.h"
    +
    +#ifdef __CHECKER__
    +# define __protected_by(x) __attribute__((require_context(x,1,999,"rdwr")))
    +# define __protected_read_by(x) __attribute__((require_context(x,1,999,"read")))
    +# define __protected_write_by(x) __attribute__((require_context(x,1,999,"write")))
    +# define __must_hold(x) __attribute__((context(x,1,1), require_context(x,1,999,"call")))
    +#else
    +# define __protected_by(x)
    +# define __protected_read_by(x)
    +# define __protected_write_by(x)
    +# define __must_hold(x)
    +#endif
    +
    +#define __no_warn(lock, stmt) do { __acquire(lock); stmt; __release(lock); } while (0)
    +
    +/* module parameter, defined in drbd_main.c */
    +extern unsigned int minor_count;
    +extern int disable_sendpage;
    +extern int allow_oos;
    +extern unsigned int cn_idx;
    +
    +#ifdef DRBD_ENABLE_FAULTS
    +extern int enable_faults;
    +extern int fault_rate;
    +extern int fault_devs;
    +#endif
    +
    +extern char usermode_helper[];
    +
    +
    +#ifndef TRUE
    +#define TRUE 1
    +#endif
    +#ifndef FALSE
    +#define FALSE 0
    +#endif
    +
    +/* I don't remember why XCPU ...
    + * This is used to wake the asender,
    + * and to interrupt sending the sending task
    + * on disconnect.
    + */
    +#define DRBD_SIG SIGXCPU
    +
    +/* This is used to stop/restart our threads.
    + * Cannot use SIGTERM nor SIGKILL, since these
    + * are sent out by init on runlevel changes
    + * I choose SIGHUP for now.
    + */
    +#define DRBD_SIGKILL SIGHUP
    +
    +/* All EEs on the free list should have ID_VACANT (== 0)
    + * freshly allocated EEs get !ID_VACANT (== 1)
    + * so if it says "cannot dereference null pointer at adress 0x00000001",
    + * it is most likely one of these :( */
    +
    +#define ID_IN_SYNC (4711ULL)
    +#define ID_OUT_OF_SYNC (4712ULL)
    +
    +#define ID_SYNCER (-1ULL)
    +#define ID_VACANT 0
    +#define is_syncer_block_id(id) ((id) == ID_SYNCER)
    +
    +struct drbd_conf;
    +
    +#ifdef DBG_ALL_SYMBOLS
    +# define STATIC
    +#else
    +# define STATIC static
    +#endif
    +
    +/*
    + * Some Message Macros
    + *************************/
    +
    +#define DUMPP(A) dev_err(DEV, #A " = %p in %s:%d\n", (A), __FILE__, __LINE__);
    +#define DUMPLU(A) dev_err(DEV, #A " = %lu in %s:%d\n", (unsigned long)(A), __FILE__, __LINE__);
    +#define DUMPLLU(A) dev_err(DEV, #A " = %llu in %s:%d\n", (unsigned long long)(A), __FILE__, __LINE__);
    +#define DUMPLX(A) dev_err(DEV, #A " = %lx in %s:%d\n", (A), __FILE__, __LINE__);
    +#define DUMPI(A) dev_err(DEV, #A " = %d in %s:%d\n", (int)(A), __FILE__, __LINE__);
    +
    +
    +/* to shorten dev_warn(DEV, "msg"); and relatives statements */
    +#define DEV (disk_to_dev(mdev->vdisk))
    +
    +#define D_ASSERT(exp) if (!(exp)) \
    + dev_err(DEV, "ASSERT( " #exp " ) in %s:%d\n", __FILE__, __LINE__)
    +
    +#define ERR_IF(exp) if (({ \
    + int _b = (exp) != 0; \
    + if (_b) dev_err(DEV, "%s: (%s) in %s:%d\n", \
    + __func__, #exp, __FILE__, __LINE__); \
    + _b; \
    + }))
    +
    +/* Defines to control fault insertion */
    +enum {
    + DRBD_FAULT_MD_WR = 0, /* meta data write */
    + DRBD_FAULT_MD_RD, /* read */
    + DRBD_FAULT_RS_WR, /* resync */
    + DRBD_FAULT_RS_RD,
    + DRBD_FAULT_DT_WR, /* data */
    + DRBD_FAULT_DT_RD,
    + DRBD_FAULT_DT_RA, /* data read ahead */
    + DRBD_FAULT_BM_ALLOC, /* bitmap allocation */
    + DRBD_FAULT_AL_EE, /* alloc ee */
    +
    + DRBD_FAULT_MAX,
    +};
    +
    +extern void trace_drbd_resync(struct drbd_conf *mdev, int level, const char *fmt, ...);
    +
    +#ifdef DRBD_ENABLE_FAULTS
    +extern unsigned int
    +_drbd_insert_fault(struct drbd_conf *mdev, unsigned int type);
    +static inline int
    +drbd_insert_fault(struct drbd_conf *mdev, unsigned int type) {
    + return fault_rate &&
    + (enable_faults & (1<<type)) &&
    + _drbd_insert_fault(mdev, type);
    +}
    +#define FAULT_ACTIVE(_m, _t) (drbd_insert_fault((_m), (_t)))
    +
    +#else
    +#define FAULT_ACTIVE(_m, _t) (0)
    +#endif
    +
    +/* integer division, round _UP_ to the next integer */
    +#define div_ceil(A, B) ((A)/(B) + ((A)%(B) ? 1 : 0))
    +/* usual integer division */
    +#define div_floor(A, B) ((A)/(B))
    +
    +/* drbd_meta-data.c (still in drbd_main.c) */
    +/* 4th incarnation of the disk layout. */
    +#define DRBD_MD_MAGIC (DRBD_MAGIC+4)
    +
    +extern struct drbd_conf **minor_table;
    +extern struct ratelimit_state drbd_ratelimit_state;
    +
    +/***
    + * on the wire
    + *********************************************************************/
    +
    +enum drbd_packets {
    + /* receiver (data socket) */
    + P_DATA = 0x00,
    + P_DATA_REPLY = 0x01, /* Response to P_DATA_REQUEST */
    + P_RS_DATA_REPLY = 0x02, /* Response to P_RS_DATA_REQUEST */
    + P_BARRIER = 0x03,
    + P_BITMAP = 0x04,
    + P_BECOME_SYNC_TARGET = 0x05,
    + P_BECOME_SYNC_SOURCE = 0x06,
    + P_UNPLUG_REMOTE = 0x07, /* Used at various times to hint the peer */
    + P_DATA_REQUEST = 0x08, /* Used to ask for a data block */
    + P_RS_DATA_REQUEST = 0x09, /* Used to ask for a data block for resync */
    + P_SYNC_PARAM = 0x0a,
    + P_PROTOCOL = 0x0b,
    + P_UUIDS = 0x0c,
    + P_SIZES = 0x0d,
    + P_STATE = 0x0e,
    + P_SYNC_UUID = 0x0f,
    + P_AUTH_CHALLENGE = 0x10,
    + P_AUTH_RESPONSE = 0x11,
    + P_STATE_CHG_REQ = 0x12,
    +
    + /* asender (meta socket */
    + P_PING = 0x13,
    + P_PING_ACK = 0x14,
    + P_RECV_ACK = 0x15, /* Used in protocol B */
    + P_WRITE_ACK = 0x16, /* Used in protocol C */
    + P_RS_WRITE_ACK = 0x17, /* Is a P_WRITE_ACK, additionally call set_in_sync(). */
    + P_DISCARD_ACK = 0x18, /* Used in proto C, two-primaries conflict detection */
    + P_NEG_ACK = 0x19, /* Sent if local disk is unusable */
    + P_NEG_DREPLY = 0x1a, /* Local disk is broken... */
    + P_NEG_RS_DREPLY = 0x1b, /* Local disk is broken... */
    + P_BARRIER_ACK = 0x1c,
    + P_STATE_CHG_REPLY = 0x1d,
    +
    + /* "new" commands, no longer fitting into the ordering scheme above */
    +
    + P_OV_REQUEST = 0x1e, /* data socket */
    + P_OV_REPLY = 0x1f,
    + P_OV_RESULT = 0x20, /* meta socket */
    + P_CSUM_RS_REQUEST = 0x21, /* data socket */
    + P_RS_IS_IN_SYNC = 0x22, /* meta socket */
    + P_SYNC_PARAM89 = 0x23, /* data socket, protocol version 89 replacement for P_SYNC_PARAM */
    + P_COMPRESSED_BITMAP = 0x24, /* compressed or otherwise encoded bitmap transfer */
    +
    + P_MAX_CMD = 0x25,
    + P_MAY_IGNORE = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
    + P_MAX_OPT_CMD = 0x101,
    +
    + /* special command ids for handshake */
    +
    + P_HAND_SHAKE_M = 0xfff1, /* First Packet on the MetaSock */
    + P_HAND_SHAKE_S = 0xfff2, /* First Packet on the Socket */
    +
    + P_HAND_SHAKE = 0xfffe /* FIXED for the next century! */
    +};
    +
    +static inline const char *cmdname(enum drbd_packets cmd)
    +{
    + /* THINK may need to become several global tables
    + * when we want to support more than
    + * one PRO_VERSION */
    + static const char *cmdnames[] = {
    + [P_DATA] = "Data",
    + [P_DATA_REPLY] = "DataReply",
    + [P_RS_DATA_REPLY] = "RSDataReply",
    + [P_BARRIER] = "Barrier",
    + [P_BITMAP] = "ReportBitMap",
    + [P_BECOME_SYNC_TARGET] = "BecomeSyncTarget",
    + [P_BECOME_SYNC_SOURCE] = "BecomeSyncSource",
    + [P_UNPLUG_REMOTE] = "UnplugRemote",
    + [P_DATA_REQUEST] = "DataRequest",
    + [P_RS_DATA_REQUEST] = "RSDataRequest",
    + [P_SYNC_PARAM] = "SyncParam",
    + [P_SYNC_PARAM89] = "SyncParam89",
    + [P_PROTOCOL] = "ReportProtocol",
    + [P_UUIDS] = "ReportUUIDs",
    + [P_SIZES] = "ReportSizes",
    + [P_STATE] = "ReportState",
    + [P_SYNC_UUID] = "ReportSyncUUID",
    + [P_AUTH_CHALLENGE] = "AuthChallenge",
    + [P_AUTH_RESPONSE] = "AuthResponse",
    + [P_PING] = "Ping",
    + [P_PING_ACK] = "PingAck",
    + [P_RECV_ACK] = "RecvAck",
    + [P_WRITE_ACK] = "WriteAck",
    + [P_RS_WRITE_ACK] = "RSWriteAck",
    + [P_DISCARD_ACK] = "DiscardAck",
    + [P_NEG_ACK] = "NegAck",
    + [P_NEG_DREPLY] = "NegDReply",
    + [P_NEG_RS_DREPLY] = "NegRSDReply",
    + [P_BARRIER_ACK] = "BarrierAck",
    + [P_STATE_CHG_REQ] = "StateChgRequest",
    + [P_STATE_CHG_REPLY] = "StateChgReply",
    + [P_OV_REQUEST] = "OVRequest",
    + [P_OV_REPLY] = "OVReply",
    + [P_OV_RESULT] = "OVResult",
    + [P_MAX_CMD] = NULL,
    + };
    +
    + if (cmd == P_HAND_SHAKE_M)
    + return "HandShakeM";
    + if (cmd == P_HAND_SHAKE_S)
    + return "HandShakeS";
    + if (cmd == P_HAND_SHAKE)
    + return "HandShake";
    + if (cmd >= P_MAX_CMD)
    + return "Unknown";
    + return cmdnames[cmd];
    +}
    +
    +/* for sending/receiving the bitmap,
    + * possibly in some encoding scheme */
    +struct bm_xfer_ctx {
    + /* "const"
    + * stores total bits and long words
    + * of the bitmap, so we don't need to
    + * call the accessor functions over and again. */
    + unsigned long bm_bits;
    + unsigned long bm_words;
    + /* during xfer, current position within the bitmap */
    + unsigned long bit_offset;
    + unsigned long word_offset;
    +
    + /* statistics; index: (h->command == P_BITMAP) */
    + unsigned packets[2];
    + unsigned bytes[2];
    +};
    +
    +extern void INFO_bm_xfer_stats(struct drbd_conf *mdev,
    + const char *direction, struct bm_xfer_ctx *c);
    +
    +static inline void bm_xfer_ctx_bit_to_word_offset(struct bm_xfer_ctx *c)
    +{
    + /* word_offset counts "native long words" (32 or 64 bit),
    + * aligned at 64 bit.
    + * Encoded packet may end at an unaligned bit offset.
    + * In case a fallback clear text packet is transmitted in
    + * between, we adjust this offset back to the last 64bit
    + * aligned "native long word", which makes coding and decoding
    + * the plain text bitmap much more convenient. */
    +#if BITS_PER_LONG == 64
    + c->word_offset = c->bit_offset >> 6;
    +#elif BITS_PER_LONG == 32
    + c->word_offset = c->bit_offset >> 5;
    + c->word_offset &= ~(1UL);
    +#else
    +# error "unsupported BITS_PER_LONG"
    +#endif
    +}
    +
    +/* This is the layout for a packet on the wire.
    + * The byteorder is the network byte order.
    + * (except block_id and barrier fields.
    + * these are pointers to local structs
    + * and have no relevance for the partner,
    + * which just echoes them as received.)
    + *
    + * NOTE that the payload starts at a long aligned offset,
    + * regardless of 32 or 64 bit arch!
    + */
    +struct p_header {
    + u32 magic;
    + u16 command;
    + u16 length; /* bytes of data after this header */
    + u8 payload[0];
    +} __attribute((packed));
    +/* 8 bytes. packet FIXED for the next century! */
    +
    +/*
    + * short commands, packets without payload, plain p_header:
    + * P_PING
    + * P_PING_ACK
    + * P_BECOME_SYNC_TARGET
    + * P_BECOME_SYNC_SOURCE
    + * P_UNPLUG_REMOTE
    + */
    +
    +/*
    + * commands with out-of-struct payload:
    + * P_BITMAP (no additional fields)
    + * P_DATA, P_DATA_REPLY (see p_data)
    + * P_COMPRESSED_BITMAP (see receive_compressed_bitmap)
    + */
    +
    +/* these defines must not be changed without changing the protocol version */
    +#define DP_HARDBARRIER 1
    +#define DP_RW_SYNC 2
    +#define DP_MAY_SET_IN_SYNC 4
    +
    +struct p_data {
    + struct p_header head;
    + u64 sector; /* 64 bits sector number */
    + u64 block_id; /* to identify the request in protocol B&C */
    + u32 seq_num;
    + u32 dp_flags;
    +} __attribute((packed));
    +
    +/*
    + * commands which share a struct:
    + * p_block_ack:
    + * P_RECV_ACK (proto B), P_WRITE_ACK (proto C),
    + * P_DISCARD_ACK (proto C, two-primaries conflict detection)
    + * p_block_req:
    + * P_DATA_REQUEST, P_RS_DATA_REQUEST
    + */
    +struct p_block_ack {
    + struct p_header head;
    + u64 sector;
    + u64 block_id;
    + u32 blksize;
    + u32 seq_num;
    +} __attribute((packed));
    +
    +
    +struct p_block_req {
    + struct p_header head;
    + u64 sector;
    + u64 block_id;
    + u32 blksize;
    + u32 pad; /* to multiple of 8 Byte */
    +} __attribute((packed));
    +
    +/*
    + * commands with their own struct for additional fields:
    + * P_HAND_SHAKE
    + * P_BARRIER
    + * P_BARRIER_ACK
    + * P_SYNC_PARAM
    + * ReportParams
    + */
    +
    +struct p_handshake {
    + struct p_header head; /* 8 bytes */
    + u32 protocol_min;
    + u32 feature_flags;
    + u32 protocol_max;
    +
    + /* should be more than enough for future enhancements
    + * for now, feature_flags and the reserverd array shall be zero.
    + */
    +
    + u32 _pad;
    + u64 reserverd[7];
    +} __attribute((packed));
    +/* 80 bytes, FIXED for the next century */
    +
    +struct p_barrier {
    + struct p_header head;
    + u32 barrier; /* barrier number _handle_ only */
    + u32 pad; /* to multiple of 8 Byte */
    +} __attribute((packed));
    +
    +struct p_barrier_ack {
    + struct p_header head;
    + u32 barrier;
    + u32 set_size;
    +} __attribute((packed));
    +
    +struct p_rs_param {
    + struct p_header head;
    + u32 rate;
    +
    + /* Since protocol version 88 and higher. */
    + char verify_alg[0];
    +} __attribute((packed));
    +
    +struct p_rs_param_89 {
    + struct p_header head;
    + u32 rate;
    + /* protocol version 89: */
    + char verify_alg[SHARED_SECRET_MAX];
    + char csums_alg[SHARED_SECRET_MAX];
    +} __attribute((packed));
    +
    +struct p_protocol {
    + struct p_header head;
    + u32 protocol;
    + u32 after_sb_0p;
    + u32 after_sb_1p;
    + u32 after_sb_2p;
    + u32 want_lose;
    + u32 two_primaries;
    +
    + /* Since protocol version 87 and higher. */
    + char integrity_alg[0];
    +
    +} __attribute((packed));
    +
    +struct p_uuids {
    + struct p_header head;
    + u64 uuid[UI_EXTENDED_SIZE];
    +} __attribute((packed));
    +
    +struct p_rs_uuid {
    + struct p_header head;
    + u64 uuid;
    +} __attribute((packed));
    +
    +struct p_sizes {
    + struct p_header head;
    + u64 d_size; /* size of disk */
    + u64 u_size; /* user requested size */
    + u64 c_size; /* current exported size */
    + u32 max_segment_size; /* Maximal size of a BIO */
    + u32 queue_order_type;
    +} __attribute((packed));
    +
    +struct p_state {
    + struct p_header head;
    + u32 state;
    +} __attribute((packed));
    +
    +struct p_req_state {
    + struct p_header head;
    + u32 mask;
    + u32 val;
    +} __attribute((packed));
    +
    +struct p_req_state_reply {
    + struct p_header head;
    + u32 retcode;
    +} __attribute((packed));
    +
    +struct p_drbd06_param {
    + u64 size;
    + u32 state;
    + u32 blksize;
    + u32 protocol;
    + u32 version;
    + u32 gen_cnt[5];
    + u32 bit_map_gen[5];
    +} __attribute((packed));
    +
    +struct p_discard {
    + struct p_header head;
    + u64 block_id;
    + u32 seq_num;
    + u32 pad;
    +} __attribute((packed));
    +
    +/* Valid values for the encoding field.
    + * Bump proto version when changing this. */
    +enum drbd_bitmap_code {
    + /* RLE_VLI_Bytes = 0,
    + * and other bit variants had been defined during
    + * algorithm evaluation. */
    + RLE_VLI_Bits = 2,
    +};
    +
    +struct p_compressed_bm {
    + struct p_header head;
    + /* (encoding & 0x0f): actual encoding, see enum drbd_bitmap_code
    + * (encoding & 0x80): polarity (set/unset) of first runlength
    + * ((encoding >> 4) & 0x07): pad_bits, number of trailing zero bits
    + * used to pad up to head.length bytes
    + */
    + u8 encoding;
    +
    + u8 code[0];
    +} __attribute((packed));
    +
    +static inline enum drbd_bitmap_code
    +DCBP_get_code(struct p_compressed_bm *p)
    +{
    + return (enum drbd_bitmap_code)(p->encoding & 0x0f);
    +}
    +
    +static inline void
    +DCBP_set_code(struct p_compressed_bm *p, enum drbd_bitmap_code code)
    +{
    + BUG_ON(code & ~0xf);
    + p->encoding = (p->encoding & ~0xf) | code;
    +}
    +
    +static inline int
    +DCBP_get_start(struct p_compressed_bm *p)
    +{
    + return (p->encoding & 0x80) != 0;
    +}
    +
    +static inline void
    +DCBP_set_start(struct p_compressed_bm *p, int set)
    +{
    + p->encoding = (p->encoding & ~0x80) | (set ? 0x80 : 0);
    +}
    +
    +static inline int
    +DCBP_get_pad_bits(struct p_compressed_bm *p)
    +{
    + return (p->encoding >> 4) & 0x7;
    +}
    +
    +static inline void
    +DCBP_set_pad_bits(struct p_compressed_bm *p, int n)
    +{
    + BUG_ON(n & ~0x7);
    + p->encoding = (p->encoding & (~0x7 << 4)) | (n << 4);
    +}
    +
    +/* one bitmap packet, including the p_header,
    + * should fit within one _architecture independend_ page.
    + * so we need to use the fixed size 4KiB page size
    + * most architechtures have used for a long time.
    + */
    +#define BM_PACKET_PAYLOAD_BYTES (4096 - sizeof(struct p_header))
    +#define BM_PACKET_WORDS (BM_PACKET_PAYLOAD_BYTES/sizeof(long))
    +#define BM_PACKET_VLI_BYTES_MAX (4096 - sizeof(struct p_compressed_bm))
    +#if (PAGE_SIZE < 4096)
    +/* drbd_send_bitmap / receive_bitmap would break horribly */
    +#error "PAGE_SIZE too small"
    +#endif
    +
    +union p_polymorph {
    + struct p_header header;
    + struct p_handshake handshake;
    + struct p_data data;
    + struct p_block_ack block_ack;
    + struct p_barrier barrier;
    + struct p_barrier_ack barrier_ack;
    + struct p_rs_param_89 rs_param_89;
    + struct p_protocol protocol;
    + struct p_sizes sizes;
    + struct p_uuids uuids;
    + struct p_state state;
    + struct p_req_state req_state;
    + struct p_req_state_reply req_state_reply;
    + struct p_block_req block_req;
    +} __attribute((packed));
    +
    +/**********************************************************************/
    +enum drbd_thread_state {
    + None,
    + Running,
    + Exiting,
    + Restarting
    +};
    +
    +struct drbd_thread {
    + spinlock_t t_lock;
    + struct task_struct *task;
    + struct completion stop;
    + enum drbd_thread_state t_state;
    + int (*function) (struct drbd_thread *);
    + struct drbd_conf *mdev;
    + int reset_cpu_mask;
    +};
    +
    +static inline enum drbd_thread_state get_t_state(struct drbd_thread *thi)
    +{
    + /* THINK testing the t_state seems to be uncritical in all cases
    + * (but thread_{start,stop}), so we can read it *without* the lock.
    + * --lge */
    +
    + smp_rmb();
    + return thi->t_state;
    +}
    +
    +
    +/*
    + * Having this as the first member of a struct provides sort of "inheritance".
    + * "derived" structs can be "drbd_queue_work()"ed.
    + * The callback should know and cast back to the descendant struct.
    + * drbd_request and drbd_epoch_entry are descendants of drbd_work.
    + */
    +struct drbd_work;
    +typedef int (*drbd_work_cb)(struct drbd_conf *, struct drbd_work *, int cancel);
    +struct drbd_work {
    + struct list_head list;
    + drbd_work_cb cb;
    +};
    +
    +struct drbd_tl_epoch;
    +struct drbd_request {
    + struct drbd_work w;
    + struct drbd_conf *mdev;
    + struct bio *private_bio;
    + struct hlist_node colision;
    + sector_t sector;
    + unsigned int size;
    + unsigned int epoch; /* barrier_nr */
    +
    + /* barrier_nr: used to check on "completion" whether this req was in
    + * the current epoch, and we therefore have to close it,
    + * starting a new epoch...
    + */
    +
    + /* up to here, the struct layout is identical to drbd_epoch_entry;
    + * we might be able to use that to our advantage... */
    +
    + struct list_head tl_requests; /* ring list in the transfer log */
    + struct bio *master_bio; /* master bio pointer */
    + unsigned long rq_state; /* see comments above _req_mod() */
    + int seq_num;
    + unsigned long start_time;
    +};
    +
    +struct drbd_tl_epoch {
    + struct drbd_work w;
    + struct list_head requests; /* requests before */
    + struct drbd_tl_epoch *next; /* pointer to the next barrier */
    + unsigned int br_number; /* the barriers identifier. */
    + int n_req; /* number of requests attached before this barrier */
    +};
    +
    +struct drbd_request;
    +
    +/* These Tl_epoch_entries may be in one of 6 lists:
    + active_ee .. data packet being written
    + sync_ee .. syncer block being written
    + done_ee .. block written, need to send P_WRITE_ACK
    + read_ee .. [RS]P_DATA_REQUEST being read
    +*/
    +
    +struct drbd_epoch {
    + struct list_head list;
    + unsigned int barrier_nr;
    + atomic_t epoch_size; /* increased on every request added. */
    + atomic_t active; /* increased on every req. added, and dec on every finished. */
    + unsigned long flags;
    +};
    +
    +/* drbd_epoch flag bits */
    +enum {
    + DE_BARRIER_IN_NEXT_EPOCH_ISSUED,
    + DE_BARRIER_IN_NEXT_EPOCH_DONE,
    + DE_CONTAINS_A_BARRIER,
    + DE_HAVE_BARRIER_NUMBER,
    + DE_IS_FINISHING,
    +};
    +
    +enum epoch_event {
    + EV_PUT,
    + EV_GOT_BARRIER_NR,
    + EV_BARRIER_DONE,
    + EV_BECAME_LAST,
    + EV_TRACE_FLUSH, /* TRACE_ are not real events, only used for tracing */
    + EV_TRACE_ADD_BARRIER, /* Doing the first write as a barrier write */
    + EV_TRACE_SETTING_BI, /* Barrier is expressed with the first write of the next epoch */
    + EV_TRACE_ALLOC,
    + EV_TRACE_FREE,
    + EV_CLEANUP = 32, /* used as flag */
    +};
    +
    +struct drbd_epoch_entry {
    + struct drbd_work w;
    + struct drbd_conf *mdev;
    + struct bio *private_bio;
    + struct hlist_node colision;
    + sector_t sector;
    + unsigned int size;
    + struct drbd_epoch *epoch;
    +
    + /* up to here, the struct layout is identical to drbd_request;
    + * we might be able to use that to our advantage... */
    +
    + unsigned int flags;
    + u64 block_id;
    +};
    +
    +struct digest_info {
    + int digest_size;
    + void *digest;
    +};
    +
    +/* ee flag bits */
    +enum {
    + __EE_CALL_AL_COMPLETE_IO,
    + __EE_CONFLICT_PENDING,
    + __EE_MAY_SET_IN_SYNC,
    + __EE_IS_BARRIER,
    +};
    +#define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
    +#define EE_CONFLICT_PENDING (1<<__EE_CONFLICT_PENDING)
    +#define EE_MAY_SET_IN_SYNC (1<<__EE_MAY_SET_IN_SYNC)
    +#define EE_IS_BARRIER (1<<__EE_IS_BARRIER)
    +
    +/* global flag bits */
    +enum {
    + CREATE_BARRIER, /* next P_DATA is preceeded by a P_BARRIER */
    + SIGNAL_ASENDER, /* whether asender wants to be interrupted */
    + SEND_PING, /* whether asender should send a ping asap */
    + WORK_PENDING, /* completion flag for drbd_disconnect */
    + STOP_SYNC_TIMER, /* tell timer to cancel itself */
    + UNPLUG_QUEUED, /* only relevant with kernel 2.4 */
    + UNPLUG_REMOTE, /* sending a "UnplugRemote" could help */
    + MD_DIRTY, /* current uuids and flags not yet on disk */
    + DISCARD_CONCURRENT, /* Set on one node, cleared on the peer! */
    + USE_DEGR_WFC_T, /* degr-wfc-timeout instead of wfc-timeout. */
    + CLUSTER_ST_CHANGE, /* Cluster wide state change going on... */
    + CL_ST_CHG_SUCCESS,
    + CL_ST_CHG_FAIL,
    + CRASHED_PRIMARY, /* This node was a crashed primary.
    + * Gets cleared when the state.conn
    + * goes into C_CONNECTED state. */
    + WRITE_BM_AFTER_RESYNC, /* A kmalloc() during resync failed */
    + NO_BARRIER_SUPP, /* underlying block device doesn't implement barriers */
    + CONSIDER_RESYNC,
    +
    + MD_NO_BARRIER, /* meta data device does not support barriers,
    + so don't even try */
    + SUSPEND_IO, /* suspend application io */
    + BITMAP_IO, /* suspend application io;
    + once no more io in flight, start bitmap io */
    + BITMAP_IO_QUEUED, /* Started bitmap IO */
    + RESYNC_AFTER_NEG, /* Resync after online grow after the attach&negotiate finished. */
    + NET_CONGESTED, /* The data socket is congested */
    +
    + CONFIG_PENDING, /* serialization of (re)configuration requests.
    + * if set, also prevents the device from dying */
    + DEVICE_DYING, /* device became unconfigured,
    + * but worker thread is still handling the cleanup.
    + * reconfiguring (nl_disk_conf, nl_net_conf) is dissalowed,
    + * while this is set. */
    +};
    +
    +struct drbd_bitmap; /* opaque for drbd_conf */
    +
    +/* TODO sort members for performance
    + * MAYBE group them further */
    +
    +/* THINK maybe we actually want to use the default "event/%s" worker threads
    + * or similar in linux 2.6, which uses per cpu data and threads.
    + *
    + * To be general, this might need a spin_lock member.
    + * For now, please use the mdev->req_lock to protect list_head,
    + * see drbd_queue_work below.
    + */
    +struct drbd_work_queue {
    + struct list_head q;
    + struct semaphore s; /* producers up it, worker down()s it */
    + spinlock_t q_lock; /* to protect the list. */
    +};
    +
    +struct drbd_socket {
    + struct drbd_work_queue work;
    + struct mutex mutex;
    + struct socket *socket;
    + /* this way we get our
    + * send/receive buffers off the stack */
    + union p_polymorph sbuf;
    + union p_polymorph rbuf;
    +};
    +
    +struct drbd_md {
    + u64 md_offset; /* sector offset to 'super' block */
    +
    + u64 la_size_sect; /* last agreed size, unit sectors */
    + u64 uuid[UI_SIZE];
    + u64 device_uuid;
    + u32 flags;
    + u32 md_size_sect;
    +
    + s32 al_offset; /* signed relative sector offset to al area */
    + s32 bm_offset; /* signed relative sector offset to bitmap */
    +
    + /* u32 al_nr_extents; important for restoring the AL
    + * is stored into sync_conf.al_extents, which in turn
    + * gets applied to act_log->nr_elements
    + */
    +};
    +
    +/* for sync_conf and other types... */
    +#define NL_PACKET(name, number, fields) struct name { fields };
    +#define NL_INTEGER(pn,pr,member) int member;
    +#define NL_INT64(pn,pr,member) __u64 member;
    +#define NL_BIT(pn,pr,member) unsigned member:1;
    +#define NL_STRING(pn,pr,member,len) unsigned char member[len]; int member ## _len;
    +#include "linux/drbd_nl.h"
    +
    +struct drbd_backing_dev {
    + struct block_device *backing_bdev;
    + struct block_device *md_bdev;
    + struct file *lo_file;
    + struct file *md_file;
    + struct drbd_md md;
    + struct disk_conf dc; /* The user provided config... */
    + sector_t known_size; /* last known size of that backing device */
    +};
    +
    +struct drbd_md_io {
    + struct drbd_conf *mdev;
    + struct completion event;
    + int error;
    +};
    +
    +struct bm_io_work {
    + struct drbd_work w;
    + char *why;
    + int (*io_fn)(struct drbd_conf *mdev);
    + void (*done)(struct drbd_conf *mdev, int rv);
    +};
    +
    +enum write_ordering_e {
    + WO_none,
    + WO_drain_io,
    + WO_bdev_flush,
    + WO_bio_barrier
    +};
    +
    +struct drbd_conf {
    + /* things that are stored as / read from meta data on disk */
    + unsigned long flags;
    +
    + /* configured by drbdsetup */
    + struct net_conf *net_conf; /* protected by inc_net() and dec_net() */
    + struct syncer_conf sync_conf;
    + struct drbd_backing_dev *bc __protected_by(local);
    +
    + sector_t p_size; /* partner's disk size */
    + struct request_queue *rq_queue;
    + struct block_device *this_bdev;
    + struct gendisk *vdisk;
    +
    + struct drbd_socket data; /* data/barrier/cstate/parameter packets */
    + struct drbd_socket meta; /* ping/ack (metadata) packets */
    + int agreed_pro_version; /* actually used protocol version */
    + unsigned long last_received; /* in jiffies, either socket */
    + unsigned int ko_count;
    + struct drbd_work resync_work,
    + unplug_work,
    + md_sync_work;
    + struct timer_list resync_timer;
    + struct timer_list md_sync_timer;
    +
    + /* Used after attach while negotiating new disk state. */
    + union drbd_state new_state_tmp;
    +
    + union drbd_state state;
    + wait_queue_head_t misc_wait;
    + wait_queue_head_t state_wait; /* upon each state change. */
    + unsigned int send_cnt;
    + unsigned int recv_cnt;
    + unsigned int read_cnt;
    + unsigned int writ_cnt;
    + unsigned int al_writ_cnt;
    + unsigned int bm_writ_cnt;
    + atomic_t ap_bio_cnt; /* Requests we need to complete */
    + atomic_t ap_pending_cnt; /* AP data packets on the wire, ack expected */
    + atomic_t rs_pending_cnt; /* RS request/data packets on the wire */
    + atomic_t unacked_cnt; /* Need to send replys for */
    + atomic_t local_cnt; /* Waiting for local completion */
    + atomic_t net_cnt; /* Users of net_conf */
    + spinlock_t req_lock;
    + struct drbd_tl_epoch *unused_spare_tle; /* for pre-allocation */
    + struct drbd_tl_epoch *newest_tle;
    + struct drbd_tl_epoch *oldest_tle;
    + struct list_head out_of_sequence_requests;
    + struct hlist_head *tl_hash;
    + unsigned int tl_hash_s;
    +
    + /* blocks to sync in this run [unit BM_BLOCK_SIZE] */
    + unsigned long rs_total;
    + /* number of sync IOs that failed in this run */
    + unsigned long rs_failed;
    + /* Syncer's start time [unit jiffies] */
    + unsigned long rs_start;
    + /* cumulated time in PausedSyncX state [unit jiffies] */
    + unsigned long rs_paused;
    + /* block not up-to-date at mark [unit BM_BLOCK_SIZE] */
    + unsigned long rs_mark_left;
    + /* marks's time [unit jiffies] */
    + unsigned long rs_mark_time;
    + /* skipped because csum was equeal [unit BM_BLOCK_SIZE] */
    + unsigned long rs_same_csum;
    + sector_t ov_position;
    + /* Start sector of out of sync range. */
    + sector_t ov_last_oos_start;
    + /* size of out-of-sync range in sectors. */
    + sector_t ov_last_oos_size;
    + unsigned long ov_left;
    + struct crypto_hash *csums_tfm;
    + struct crypto_hash *verify_tfm;
    +
    + struct drbd_thread receiver;
    + struct drbd_thread worker;
    + struct drbd_thread asender;
    + struct drbd_bitmap *bitmap;
    + unsigned long bm_resync_fo; /* bit offset for drbd_bm_find_next */
    +
    + /* Used to track operations of resync... */
    + struct lru_cache *resync;
    + /* Number of locked elements in resync LRU */
    + unsigned int resync_locked;
    + /* resync extent number waiting for application requests */
    + unsigned int resync_wenr;
    +
    + int open_cnt;
    + u64 *p_uuid;
    + struct drbd_epoch *current_epoch;
    + spinlock_t epoch_lock;
    + unsigned int epochs;
    + enum write_ordering_e write_ordering;
    + struct list_head active_ee; /* IO in progress */
    + struct list_head sync_ee; /* IO in progress */
    + struct list_head done_ee; /* send ack */
    + struct list_head read_ee; /* IO in progress */
    + struct list_head net_ee; /* zero-copy network send in progress */
    + struct hlist_head *ee_hash; /* is proteced by req_lock! */
    + unsigned int ee_hash_s;
    +
    + /* this one is protected by ee_lock, single thread */
    + struct drbd_epoch_entry *last_write_w_barrier;
    +
    + int next_barrier_nr;
    + struct hlist_head *app_reads_hash; /* is proteced by req_lock */
    + struct list_head resync_reads;
    + atomic_t pp_in_use;
    + wait_queue_head_t ee_wait;
    + struct page *md_io_page; /* one page buffer for md_io */
    + struct page *md_io_tmpp; /* for hardsect != 512 [s390 only?] */
    + struct mutex md_io_mutex; /* protects the md_io_buffer */
    + spinlock_t al_lock;
    + wait_queue_head_t al_wait;
    + struct lru_cache *act_log; /* activity log */
    + unsigned int al_tr_number;
    + int al_tr_cycle;
    + int al_tr_pos; /* position of the next transaction in the journal */
    + struct crypto_hash *cram_hmac_tfm;
    + struct crypto_hash *integrity_w_tfm; /* to be used by the worker thread */
    + struct crypto_hash *integrity_r_tfm; /* to be used by the receiver thread */
    + void *int_dig_out;
    + void *int_dig_in;
    + void *int_dig_vv;
    + wait_queue_head_t seq_wait;
    + atomic_t packet_seq;
    + unsigned int peer_seq;
    + spinlock_t peer_seq_lock;
    + unsigned int minor;
    + unsigned long comm_bm_set; /* communicated number of set bits. */
    + cpumask_t cpu_mask;
    + struct bm_io_work bm_io_work;
    + u64 ed_uuid; /* UUID of the exposed data */
    + struct mutex state_mutex;
    + char congestion_reason; /* Why we where congested... */
    +};
    +
    +static inline struct drbd_conf *minor_to_mdev(unsigned int minor)
    +{
    + struct drbd_conf *mdev;
    +
    + mdev = minor < minor_count ? minor_table[minor] : NULL;
    +
    + return mdev;
    +}
    +
    +static inline unsigned int mdev_to_minor(struct drbd_conf *mdev)
    +{
    + return mdev->minor;
    +}
    +
    +/* returns 1 if it was successfull,
    + * returns 0 if there was no data socket.
    + * so wherever you are going to use the data.socket, e.g. do
    + * if (!drbd_get_data_sock(mdev))
    + * return 0;
    + * CODE();
    + * drbd_put_data_sock(mdev);
    + */
    +static inline int drbd_get_data_sock(struct drbd_conf *mdev)
    +{
    + mutex_lock(&mdev->data.mutex);
    + /* drbd_disconnect() could have called drbd_free_sock()
    + * while we were waiting in down()... */
    + if (unlikely(mdev->data.socket == NULL)) {
    + mutex_unlock(&mdev->data.mutex);
    + return 0;
    + }
    + return 1;
    +}
    +
    +static inline void drbd_put_data_sock(struct drbd_conf *mdev)
    +{
    + mutex_unlock(&mdev->data.mutex);
    +}
    +
    +/*
    + * function declarations
    + *************************/
    +
    +/* drbd_main.c */
    +
    +enum chg_state_flags {
    + CS_HARD = 1,
    + CS_VERBOSE = 2,
    + CS_WAIT_COMPLETE = 4,
    + CS_SERIALIZE = 8,
    + CS_ORDERED = CS_WAIT_COMPLETE + CS_SERIALIZE,
    +};
    +
    +extern void drbd_init_set_defaults(struct drbd_conf *mdev);
    +extern int drbd_change_state(struct drbd_conf *mdev, enum chg_state_flags f,
    + union drbd_state mask, union drbd_state val);
    +extern void drbd_force_state(struct drbd_conf *, union drbd_state,
    + union drbd_state);
    +extern int _drbd_request_state(struct drbd_conf *, union drbd_state,
    + union drbd_state, enum chg_state_flags);
    +extern int __drbd_set_state(struct drbd_conf *, union drbd_state,
    + enum chg_state_flags, struct completion *done);
    +extern void print_st_err(struct drbd_conf *, union drbd_state,
    + union drbd_state, int);
    +extern int drbd_thread_start(struct drbd_thread *thi);
    +extern void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait);
    +#ifdef CONFIG_SMP
    +extern void drbd_thread_current_set_cpu(struct drbd_conf *mdev);
    +extern cpumask_t drbd_calc_cpu_mask(struct drbd_conf *mdev);
    +#else
    +#define drbd_thread_current_set_cpu(A) ({})
    +#define drbd_calc_cpu_mask(A) CPU_MASK_ALL
    +#endif
    +extern void drbd_free_resources(struct drbd_conf *mdev);
    +extern void tl_release(struct drbd_conf *mdev, unsigned int barrier_nr,
    + unsigned int set_size);
    +extern void tl_clear(struct drbd_conf *mdev);
    +extern void _tl_add_barrier(struct drbd_conf *, struct drbd_tl_epoch *);
    +extern void drbd_free_sock(struct drbd_conf *mdev);
    +extern int drbd_send(struct drbd_conf *mdev, struct socket *sock,
    + void *buf, size_t size, unsigned msg_flags);
    +extern int drbd_send_protocol(struct drbd_conf *mdev);
    +extern int drbd_send_uuids(struct drbd_conf *mdev);
    +extern int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev);
    +extern int drbd_send_sync_uuid(struct drbd_conf *mdev, u64 val);
    +extern int drbd_send_sizes(struct drbd_conf *mdev);
    +extern int _drbd_send_state(struct drbd_conf *mdev);
    +extern int drbd_send_state(struct drbd_conf *mdev);
    +extern int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,
    + enum drbd_packets cmd, struct p_header *h,
    + size_t size, unsigned msg_flags);
    +#define USE_DATA_SOCKET 1
    +#define USE_META_SOCKET 0
    +extern int drbd_send_cmd(struct drbd_conf *mdev, int use_data_socket,
    + enum drbd_packets cmd, struct p_header *h,
    + size_t size);
    +extern int drbd_send_cmd2(struct drbd_conf *mdev, enum drbd_packets cmd,
    + char *data, size_t size);
    +extern int drbd_send_sync_param(struct drbd_conf *mdev, struct syncer_conf *sc);
    +extern int drbd_send_b_ack(struct drbd_conf *mdev, u32 barrier_nr,
    + u32 set_size);
    +extern int drbd_send_ack(struct drbd_conf *mdev, enum drbd_packets cmd,
    + struct drbd_epoch_entry *e);
    +extern int drbd_send_ack_rp(struct drbd_conf *mdev, enum drbd_packets cmd,
    + struct p_block_req *rp);
    +extern int drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packets cmd,
    + struct p_data *dp);
    +extern int drbd_send_ack_ex(struct drbd_conf *mdev, enum drbd_packets cmd,
    + sector_t sector, int blksize, u64 block_id);
    +extern int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
    + int offset, size_t size);
    +extern int drbd_send_block(struct drbd_conf *mdev, enum drbd_packets cmd,
    + struct drbd_epoch_entry *e);
    +extern int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req);
    +extern int _drbd_send_barrier(struct drbd_conf *mdev,
    + struct drbd_tl_epoch *barrier);
    +extern int drbd_send_drequest(struct drbd_conf *mdev, int cmd,
    + sector_t sector, int size, u64 block_id);
    +extern int drbd_send_drequest_csum(struct drbd_conf *mdev,
    + sector_t sector,int size,
    + void *digest, int digest_size,
    + enum drbd_packets cmd);
    +extern int drbd_send_ov_request(struct drbd_conf *mdev,sector_t sector,int size);
    +
    +extern int drbd_send_bitmap(struct drbd_conf *mdev);
    +extern int _drbd_send_bitmap(struct drbd_conf *mdev);
    +extern int drbd_send_sr_reply(struct drbd_conf *mdev, int retcode);
    +extern void drbd_free_bc(struct drbd_backing_dev *bc);
    +extern int drbd_io_error(struct drbd_conf *mdev, int forcedetach);
    +extern void drbd_mdev_cleanup(struct drbd_conf *mdev);
    +
    +/* drbd_meta-data.c (still in drbd_main.c) */
    +extern void drbd_md_sync(struct drbd_conf *mdev);
    +extern int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev);
    +/* maybe define them below as inline? */
    +extern void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);
    +extern void _drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);
    +extern void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local);
    +extern void _drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local);
    +extern void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local);
    +extern void drbd_md_set_flag(struct drbd_conf *mdev, int flags) __must_hold(local);
    +extern void drbd_md_clear_flag(struct drbd_conf *mdev, int flags)__must_hold(local);
    +extern int drbd_md_test_flag(struct drbd_backing_dev *, int);
    +extern void drbd_md_mark_dirty(struct drbd_conf *mdev);
    +extern void drbd_queue_bitmap_io(struct drbd_conf *mdev,
    + int (*io_fn)(struct drbd_conf *),
    + void (*done)(struct drbd_conf *, int),
    + char *why);
    +extern int drbd_bmio_set_n_write(struct drbd_conf *mdev);
    +extern int drbd_bmio_clear_n_write(struct drbd_conf *mdev);
    +extern int drbd_bitmap_io(struct drbd_conf *mdev, int (*io_fn)(struct drbd_conf *), char *why);
    +
    +
    +/* Meta data layout
    + We reserve a 128MB Block (4k aligned)
    + * either at the end of the backing device
    + * or on a seperate meta data device. */
    +
    +#define MD_RESERVED_SECT (128LU << 11) /* 128 MB, unit sectors */
    +/* The following numbers are sectors */
    +#define MD_AL_OFFSET 8 /* 8 Sectors after start of meta area */
    +#define MD_AL_MAX_SIZE 64 /* = 32 kb LOG ~ 3776 extents ~ 14 GB Storage */
    +/* Allows up to about 3.8TB */
    +#define MD_BM_OFFSET (MD_AL_OFFSET + MD_AL_MAX_SIZE)
    +
    +/* Since the smalles IO unit is usually 512 byte */
    +#define MD_HARDSECT_B 9
    +#define MD_HARDSECT (1<<MD_HARDSECT_B)
    +
    +/* activity log */
    +#define AL_EXTENTS_PT ((MD_HARDSECT-12)/8-1) /* 61 ; Extents per 512B sector */
    +#define AL_EXTENT_SIZE_B 22 /* One extent represents 4M Storage */
    +#define AL_EXTENT_SIZE (1<<AL_EXTENT_SIZE_B)
    +
    +#if BITS_PER_LONG == 32
    +#define LN2_BPL 5
    +#define cpu_to_lel(A) cpu_to_le32(A)
    +#define lel_to_cpu(A) le32_to_cpu(A)
    +#elif BITS_PER_LONG == 64
    +#define LN2_BPL 6
    +#define cpu_to_lel(A) cpu_to_le64(A)
    +#define lel_to_cpu(A) le64_to_cpu(A)
    +#else
    +#error "LN2 of BITS_PER_LONG unknown!"
    +#endif
    +
    +/* resync bitmap */
    +/* 16MB sized 'bitmap extent' to track syncer usage */
    +struct bm_extent {
    + struct lc_element lce;
    + int rs_left; /* number of bits set (out of sync) in this extent. */
    + int rs_failed; /* number of failed resync requests in this extent. */
    + unsigned long flags;
    +};
    +
    +#define BME_NO_WRITES 0 /* bm_extent.flags: no more requests on this one! */
    +#define BME_LOCKED 1 /* bm_extent.flags: syncer active on this one. */
    +
    +/* drbd_bitmap.c */
    +/*
    + * We need to store one bit for a block.
    + * Example: 1GB disk @ 4096 byte blocks ==> we need 32 KB bitmap.
    + * Bit 0 ==> local node thinks this block is binary identical on both nodes
    + * Bit 1 ==> local node thinks this block needs to be synced.
    + */
    +
    +#define BM_BLOCK_SIZE_B 12 /* 4k per bit */
    +#define BM_BLOCK_SIZE (1<<BM_BLOCK_SIZE_B)
    +/* (9+3) : 512 bytes @ 8 bits; representing 16M storage
    + * per sector of on disk bitmap */
    +#define BM_EXT_SIZE_B (BM_BLOCK_SIZE_B + MD_HARDSECT_B + 3) /* = 24 */
    +#define BM_EXT_SIZE (1<<BM_EXT_SIZE_B)
    +
    +#if (BM_EXT_SIZE_B != 24) || (BM_BLOCK_SIZE_B != 12)
    +#error "HAVE YOU FIXED drbdmeta AS WELL??"
    +#endif
    +
    +/* thus many _storage_ sectors are described by one bit */
    +#define BM_SECT_TO_BIT(x) ((x)>>(BM_BLOCK_SIZE_B-9))
    +#define BM_BIT_TO_SECT(x) ((sector_t)(x)<<(BM_BLOCK_SIZE_B-9))
    +#define BM_SECT_PER_BIT BM_BIT_TO_SECT(1)
    +
    +/* bit to represented kilo byte conversion */
    +#define Bit2KB(bits) ((bits)<<(BM_BLOCK_SIZE_B-10))
    +
    +/* in which _bitmap_ extent (resp. sector) the bit for a certain
    + * _storage_ sector is located in */
    +#define BM_SECT_TO_EXT(x) ((x)>>(BM_EXT_SIZE_B-9))
    +
    +/* how much _storage_ sectors we have per bitmap sector */
    +#define BM_EXT_TO_SECT(x) ((sector_t)(x) << (BM_EXT_SIZE_B-9))
    +#define BM_SECT_PER_EXT BM_EXT_TO_SECT(1)
    +
    +/* in one sector of the bitmap, we have this many activity_log extents. */
    +#define AL_EXT_PER_BM_SECT (1 << (BM_EXT_SIZE_B - AL_EXTENT_SIZE_B))
    +#define BM_WORDS_PER_AL_EXT (1 << (AL_EXTENT_SIZE_B-BM_BLOCK_SIZE_B-LN2_BPL))
    +
    +#define BM_BLOCKS_PER_BM_EXT_B (BM_EXT_SIZE_B - BM_BLOCK_SIZE_B)
    +#define BM_BLOCKS_PER_BM_EXT_MASK ((1<<BM_BLOCKS_PER_BM_EXT_B) - 1)
    +
    +/* the extent in "PER_EXTENT" below is an activity log extent
    + * we need that many (long words/bytes) to store the bitmap
    + * of one AL_EXTENT_SIZE chunk of storage.
    + * we can store the bitmap for that many AL_EXTENTS within
    + * one sector of the _on_disk_ bitmap:
    + * bit 0 bit 37 bit 38 bit (512*8)-1
    + * ...|........|........|.. // ..|........|
    + * sect. 0 `296 `304 ^(512*8*8)-1
    + *
    +#define BM_WORDS_PER_EXT ( (AL_EXT_SIZE/BM_BLOCK_SIZE) / BITS_PER_LONG )
    +#define BM_BYTES_PER_EXT ( (AL_EXT_SIZE/BM_BLOCK_SIZE) / 8 ) // 128
    +#define BM_EXT_PER_SECT ( 512 / BM_BYTES_PER_EXTENT ) // 4
    + */
    +
    +#define DRBD_MAX_SECTORS_32 (0xffffffffLU)
    +#define DRBD_MAX_SECTORS_BM \
    + ((MD_RESERVED_SECT - MD_BM_OFFSET) * (1LL<<(BM_EXT_SIZE_B-9)))
    +#if DRBD_MAX_SECTORS_BM < DRBD_MAX_SECTORS_32
    +#define DRBD_MAX_SECTORS DRBD_MAX_SECTORS_BM
    +#define DRBD_MAX_SECTORS_FLEX DRBD_MAX_SECTORS_BM
    +#elif !defined(CONFIG_LBD) && BITS_PER_LONG == 32
    +#define DRBD_MAX_SECTORS DRBD_MAX_SECTORS_32
    +#define DRBD_MAX_SECTORS_FLEX DRBD_MAX_SECTORS_32
    +#else
    +#define DRBD_MAX_SECTORS DRBD_MAX_SECTORS_BM
    +/* 16 TB in units of sectors */
    +#if BITS_PER_LONG == 32
    +/* adjust by one page worth of bitmap,
    + * so we won't wrap around in drbd_bm_find_next_bit.
    + * you should use 64bit OS for that much storage, anyways. */
    +#define DRBD_MAX_SECTORS_FLEX BM_BIT_TO_SECT(0xffff7fff)
    +#else
    +#define DRBD_MAX_SECTORS_FLEX BM_BIT_TO_SECT(0x1LU << 32)
    +#endif
    +#endif
    +
    +/* Sector shift value for the "hash" functions of tl_hash and ee_hash tables.
    + * With a value of 6 all IO in one 32K block make it to the same slot of the
    + * hash table. */
    +#define HT_SHIFT 6
    +#define DRBD_MAX_SEGMENT_SIZE (1U<<(9+HT_SHIFT))
    +
    +/* Number of elements in the app_reads_hash */
    +#define APP_R_HSIZE 15
    +
    +extern int drbd_bm_init(struct drbd_conf *mdev);
    +extern int drbd_bm_resize(struct drbd_conf *mdev, sector_t sectors);
    +extern void drbd_bm_cleanup(struct drbd_conf *mdev);
    +extern void drbd_bm_set_all(struct drbd_conf *mdev);
    +extern void drbd_bm_clear_all(struct drbd_conf *mdev);
    +extern int drbd_bm_set_bits(
    + struct drbd_conf *mdev, unsigned long s, unsigned long e);
    +extern int drbd_bm_clear_bits(
    + struct drbd_conf *mdev, unsigned long s, unsigned long e);
    +/* bm_set_bits variant for use while holding drbd_bm_lock */
    +extern int _drbd_bm_set_bits(struct drbd_conf *mdev,
    + const unsigned long s, const unsigned long e);
    +extern int drbd_bm_test_bit(struct drbd_conf *mdev, unsigned long bitnr);
    +extern int drbd_bm_e_weight(struct drbd_conf *mdev, unsigned long enr);
    +extern int drbd_bm_write_sect(struct drbd_conf *mdev, unsigned long enr) __must_hold(local);
    +extern int drbd_bm_read(struct drbd_conf *mdev) __must_hold(local);
    +extern int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local);
    +extern unsigned long drbd_bm_ALe_set_all(struct drbd_conf *mdev,
    + unsigned long al_enr);
    +extern size_t drbd_bm_words(struct drbd_conf *mdev);
    +extern unsigned long drbd_bm_bits(struct drbd_conf *mdev);
    +extern sector_t drbd_bm_capacity(struct drbd_conf *mdev);
    +extern unsigned long drbd_bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo);
    +/* bm_find_next variants for use while you hold drbd_bm_lock() */
    +extern unsigned long _drbd_bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo);
    +extern unsigned long _drbd_bm_find_next_zero(struct drbd_conf *mdev, unsigned long bm_fo);
    +extern unsigned long drbd_bm_total_weight(struct drbd_conf *mdev);
    +extern int drbd_bm_rs_done(struct drbd_conf *mdev);
    +/* for receive_bitmap */
    +extern void drbd_bm_merge_lel(struct drbd_conf *mdev, size_t offset,
    + size_t number, unsigned long *buffer);
    +/* for _drbd_send_bitmap and drbd_bm_write_sect */
    +extern void drbd_bm_get_lel(struct drbd_conf *mdev, size_t offset,
    + size_t number, unsigned long *buffer);
    +
    +extern void drbd_bm_lock(struct drbd_conf *mdev, char *why);
    +extern void drbd_bm_unlock(struct drbd_conf *mdev);
    +
    +extern void _drbd_bm_recount_bits(struct drbd_conf *mdev, char *file, int line);
    +#define drbd_bm_recount_bits(mdev) \
    + _drbd_bm_recount_bits(mdev, __FILE__, __LINE__)
    +extern int drbd_bm_count_bits(struct drbd_conf *mdev, const unsigned long s, const unsigned long e);
    +/* drbd_main.c */
    +
    +extern struct kmem_cache *drbd_request_cache;
    +extern struct kmem_cache *drbd_ee_cache;
    +extern mempool_t *drbd_request_mempool;
    +extern mempool_t *drbd_ee_mempool;
    +
    +extern struct page *drbd_pp_pool; /* drbd's page pool */
    +extern spinlock_t drbd_pp_lock;
    +extern int drbd_pp_vacant;
    +extern wait_queue_head_t drbd_pp_wait;
    +
    +extern rwlock_t global_state_lock;
    +
    +extern struct drbd_conf *drbd_new_device(unsigned int minor);
    +extern void drbd_free_mdev(struct drbd_conf *mdev);
    +
    +extern int proc_details;
    +
    +/* drbd_req */
    +extern int drbd_make_request_26(struct request_queue *q, struct bio *bio);
    +extern int drbd_read_remote(struct drbd_conf *mdev, struct drbd_request *req);
    +extern int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec);
    +extern int is_valid_ar_handle(struct drbd_request *, sector_t);
    +
    +
    +/* drbd_nl.c */
    +extern void drbd_suspend_io(struct drbd_conf *mdev);
    +extern void drbd_resume_io(struct drbd_conf *mdev);
    +extern char *ppsize(char *buf, unsigned long long size);
    +extern sector_t drbd_new_dev_size(struct drbd_conf *,
    + struct drbd_backing_dev *);
    +enum determine_dev_size { dev_size_error = -1, unchanged = 0, shrunk = 1, grew = 2 };
    +extern enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *) __must_hold(local);
    +extern void resync_after_online_grow(struct drbd_conf *);
    +extern void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int) __must_hold(local);
    +extern int drbd_set_role(struct drbd_conf *mdev, enum drbd_role new_role,
    + int force);
    +enum drbd_disk_state drbd_try_outdate_peer(struct drbd_conf *mdev);
    +extern int drbd_khelper(struct drbd_conf *mdev, char *cmd);
    +
    +/* drbd_worker.c */
    +extern int drbd_worker(struct drbd_thread *thi);
    +extern void drbd_alter_sa(struct drbd_conf *mdev, int na);
    +extern void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side);
    +extern void resume_next_sg(struct drbd_conf *mdev);
    +extern void suspend_other_sg(struct drbd_conf *mdev);
    +extern int drbd_resync_finished(struct drbd_conf *mdev);
    +/* maybe rather drbd_main.c ? */
    +extern int drbd_md_sync_page_io(struct drbd_conf *mdev,
    + struct drbd_backing_dev *bdev, sector_t sector, int rw);
    +extern void drbd_ov_oos_found(struct drbd_conf*, sector_t, int);
    +
    +static inline void ov_oos_print(struct drbd_conf *mdev)
    +{
    + if (mdev->ov_last_oos_size) {
    + dev_err(DEV, "Out of sync: start=%llu, size=%lu (sectors)\n",
    + (unsigned long long)mdev->ov_last_oos_start,
    + (unsigned long)mdev->ov_last_oos_size);
    + }
    + mdev->ov_last_oos_size=0;
    +}
    +
    +
    +void drbd_csum(struct drbd_conf *, struct crypto_hash *, struct bio *, void *);
    +/* worker callbacks */
    +extern int w_req_cancel_conflict(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_read_retry_remote(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_e_end_data_req(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_e_end_rsdata_req(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_e_end_csum_rs_req(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_e_end_ov_reply(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_e_end_ov_req(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_ov_finished(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_resync_inactive(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_resume_next_sg(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_io_error(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_send_write_hint(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_make_resync_request(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_send_dblock(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_send_barrier(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_send_read_req(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_prev_work_done(struct drbd_conf *, struct drbd_work *, int);
    +extern int w_e_reissue(struct drbd_conf *, struct drbd_work *, int);
    +
    +extern void resync_timer_fn(unsigned long data);
    +
    +/* drbd_receiver.c */
    +extern int drbd_release_ee(struct drbd_conf *mdev, struct list_head *list);
    +extern struct drbd_epoch_entry *drbd_alloc_ee(struct drbd_conf *mdev,
    + u64 id,
    + sector_t sector,
    + unsigned int data_size,
    + gfp_t gfp_mask) __must_hold(local);
    +extern void drbd_free_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e);
    +extern void drbd_wait_ee_list_empty(struct drbd_conf *mdev,
    + struct list_head *head);
    +extern void _drbd_wait_ee_list_empty(struct drbd_conf *mdev,
    + struct list_head *head);
    +extern void drbd_set_recv_tcq(struct drbd_conf *mdev, int tcq_enabled);
    +extern void _drbd_clear_done_ee(struct drbd_conf *mdev);
    +
    +/* yes, there is kernel_setsockopt, but only since 2.6.18. we don't need to
    + * mess with get_fs/set_fs, we know we are KERNEL_DS always. */
    +static inline int drbd_setsockopt(struct socket *sock, int level, int optname,
    + char __user *optval, int optlen)
    +{
    + int err;
    + if (level == SOL_SOCKET)
    + err = sock_setsockopt(sock, level, optname, optval, optlen);
    + else
    + err = sock->ops->setsockopt(sock, level, optname, optval,
    + optlen);
    + return err;
    +}
    +
    +static inline void drbd_tcp_cork(struct socket *sock)
    +{
    + int __user val = 1;
    + (void) drbd_setsockopt(sock, SOL_TCP, TCP_CORK,
    + (char __user *)&val, sizeof(val));
    +}
    +
    +static inline void drbd_tcp_uncork(struct socket *sock)
    +{
    + int __user val = 0;
    + (void) drbd_setsockopt(sock, SOL_TCP, TCP_CORK,
    + (char __user *)&val, sizeof(val));
    +}
    +
    +static inline void drbd_tcp_nodelay(struct socket *sock)
    +{
    + int __user val = 1;
    + (void) drbd_setsockopt(sock, SOL_TCP, TCP_NODELAY,
    + (char __user *)&val, sizeof(val));
    +}
    +
    +static inline void drbd_tcp_quickack(struct socket *sock)
    +{
    + int __user val = 1;
    + (void) drbd_setsockopt(sock, SOL_TCP, TCP_QUICKACK,
    + (char __user *)&val, sizeof(val));
    +}
    +
    +void drbd_bump_write_ordering(struct drbd_conf *mdev, enum write_ordering_e wo);
    +
    +/* drbd_proc.c */
    +extern struct proc_dir_entry *drbd_proc;
    +extern struct file_operations drbd_proc_fops;
    +extern const char *conns_to_name(enum drbd_conns s);
    +extern const char *roles_to_name(enum drbd_role s);
    +
    +/* drbd_actlog.c */
    +extern void drbd_al_begin_io(struct drbd_conf *mdev, sector_t sector);
    +extern void drbd_al_complete_io(struct drbd_conf *mdev, sector_t sector);
    +extern void drbd_rs_complete_io(struct drbd_conf *mdev, sector_t sector);
    +extern int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector);
    +extern int drbd_try_rs_begin_io(struct drbd_conf *mdev, sector_t sector);
    +extern void drbd_rs_cancel_all(struct drbd_conf *mdev);
    +extern int drbd_rs_del_all(struct drbd_conf *mdev);
    +extern void drbd_rs_failed_io(struct drbd_conf *mdev,
    + sector_t sector, int size);
    +extern int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *);
    +extern void __drbd_set_in_sync(struct drbd_conf *mdev, sector_t sector,
    + int size, const char *file, const unsigned int line);
    +#define drbd_set_in_sync(mdev, sector, size) \
    + __drbd_set_in_sync(mdev, sector, size, __FILE__, __LINE__)
    +extern void __drbd_set_out_of_sync(struct drbd_conf *mdev, sector_t sector,
    + int size, const char *file, const unsigned int line);
    +#define drbd_set_out_of_sync(mdev, sector, size) \
    + __drbd_set_out_of_sync(mdev, sector, size, __FILE__, __LINE__)
    +extern void drbd_al_apply_to_bm(struct drbd_conf *mdev);
    +extern void drbd_al_to_on_disk_bm(struct drbd_conf *mdev);
    +extern void drbd_al_shrink(struct drbd_conf *mdev);
    +
    +
    +/* drbd_nl.c */
    +
    +void drbd_nl_cleanup(void);
    +int __init drbd_nl_init(void);
    +void drbd_bcast_state(struct drbd_conf *mdev, union drbd_state);
    +void drbd_bcast_sync_progress(struct drbd_conf *mdev);
    +void drbd_bcast_ee(struct drbd_conf *mdev,
    + const char *reason, const int dgs,
    + const char* seen_hash, const char* calc_hash,
    + const struct drbd_epoch_entry* e);
    +
    +
    +/** DRBD State macros:
    + * These macros are used to express state changes in easily readable form.
    + *
    + * The NS macros expand to a mask and a value, that can be bit ored onto the
    + * current state as soon as the spinlock (req_lock) was taken.
    + *
    + * The _NS macros are used for state functions that get called with the
    + * spinlock. These macros expand directly to the new state value.
    + *
    + * Besides the basic forms NS() and _NS() additional _?NS[23] are defined
    + * to express state changes that affect more than one aspect of the state.
    + *
    + * E.g. NS2(conn, C_CONNECTED, peer, R_SECONDARY)
    + * Means that the network connection was established and that the peer
    + * is in secondary role.
    + */
    +#define role_MASK R_MASK
    +#define peer_MASK R_MASK
    +#define disk_MASK D_MASK
    +#define pdsk_MASK D_MASK
    +#define conn_MASK C_MASK
    +#define susp_MASK 1
    +#define user_isp_MASK 1
    +#define aftr_isp_MASK 1
    +
    +#define NS(T, S) \
    + ({ union drbd_state mask; mask.i = 0; mask.T = T##_MASK; mask; }), \
    + ({ union drbd_state val; val.i = 0; val.T = (S); val; })
    +#define NS2(T1, S1, T2, S2) \
    + ({ union drbd_state mask; mask.i = 0; mask.T1 = T1##_MASK; \
    + mask.T2 = T2##_MASK; mask; }), \
    + ({ union drbd_state val; val.i = 0; val.T1 = (S1); \
    + val.T2 = (S2); val; })
    +#define NS3(T1, S1, T2, S2, T3, S3) \
    + ({ union drbd_state mask; mask.i = 0; mask.T1 = T1##_MASK; \
    + mask.T2 = T2##_MASK; mask.T3 = T3##_MASK; mask; }), \
    + ({ union drbd_state val; val.i = 0; val.T1 = (S1); \
    + val.T2 = (S2); val.T3 = (S3); val; })
    +
    +#define _NS(D, T, S) \
    + D, ({ union drbd_state __ns; __ns.i = D->state.i; __ns.T = (S); __ns; })
    +#define _NS2(D, T1, S1, T2, S2) \
    + D, ({ union drbd_state __ns; __ns.i = D->state.i; __ns.T1 = (S1); \
    + __ns.T2 = (S2); __ns; })
    +#define _NS3(D, T1, S1, T2, S2, T3, S3) \
    + D, ({ union drbd_state __ns; __ns.i = D->state.i; __ns.T1 = (S1); \
    + __ns.T2 = (S2); __ns.T3 = (S3); __ns; })
    +
    +/*
    + * inline helper functions
    + *************************/
    +
    +static inline void drbd_state_lock(struct drbd_conf *mdev)
    +{
    + wait_event(mdev->misc_wait,
    + !test_and_set_bit(CLUSTER_ST_CHANGE, &mdev->flags));
    +}
    +
    +static inline void drbd_state_unlock(struct drbd_conf *mdev)
    +{
    + clear_bit(CLUSTER_ST_CHANGE, &mdev->flags);
    + wake_up(&mdev->misc_wait);
    +}
    +
    +static inline int _drbd_set_state(struct drbd_conf *mdev,
    + union drbd_state ns, enum chg_state_flags flags,
    + struct completion *done)
    +{
    + int rv;
    +
    + read_lock(&global_state_lock);
    + rv = __drbd_set_state(mdev, ns, flags, done);
    + read_unlock(&global_state_lock);
    +
    + return rv;
    +}
    +
    +static inline int drbd_request_state(struct drbd_conf *mdev,
    + union drbd_state mask,
    + union drbd_state val)
    +{
    + return _drbd_request_state(mdev, mask, val, CS_VERBOSE + CS_ORDERED);
    +}
    +
    +/**
    + * drbd_chk_io_error: Handles the on_io_error setting, should be called from
    + * all io completion handlers. See also drbd_io_error().
    + */
    +static inline void __drbd_chk_io_error(struct drbd_conf *mdev, int forcedetach)
    +{
    + switch (mdev->bc->dc.on_io_error) {
    + case EP_PASS_ON:
    + if (!forcedetach) {
    + if (printk_ratelimit())
    + dev_err(DEV, "Local IO failed. Passing error on...\n");
    + break;
    + }
    + /* NOTE fall through to detach case if forcedetach set */
    + case EP_DETACH:
    + case EP_CALL_HELPER:
    + if (mdev->state.disk > D_FAILED) {
    + _drbd_set_state(_NS(mdev, disk, D_FAILED), CS_HARD, NULL);
    + dev_err(DEV, "Local IO failed. Detaching...\n");
    + }
    + break;
    + }
    +}
    +
    +static inline void drbd_chk_io_error(struct drbd_conf *mdev,
    + int error, int forcedetach)
    +{
    + if (error) {
    + unsigned long flags;
    + spin_lock_irqsave(&mdev->req_lock, flags);
    + __drbd_chk_io_error(mdev, forcedetach);
    + spin_unlock_irqrestore(&mdev->req_lock, flags);
    + }
    +}
    +
    +/* Returns the first sector number of our meta data,
    + * which, for internal meta data, happens to be the maximum capacity
    + * we could agree upon with our peer
    + */
    +static inline sector_t drbd_md_first_sector(struct drbd_backing_dev *bdev)
    +{
    + switch (bdev->dc.meta_dev_idx) {
    + case DRBD_MD_INDEX_INTERNAL:
    + case DRBD_MD_INDEX_FLEX_INT:
    + return bdev->md.md_offset + bdev->md.bm_offset;
    + case DRBD_MD_INDEX_FLEX_EXT:
    + default:
    + return bdev->md.md_offset;
    + }
    +}
    +
    +/* returns the last sector number of our meta data,
    + * to be able to catch out of band md access */
    +static inline sector_t drbd_md_last_sector(struct drbd_backing_dev *bdev)
    +{
    + switch (bdev->dc.meta_dev_idx) {
    + case DRBD_MD_INDEX_INTERNAL:
    + case DRBD_MD_INDEX_FLEX_INT:
    + return bdev->md.md_offset + MD_AL_OFFSET - 1;
    + case DRBD_MD_INDEX_FLEX_EXT:
    + default:
    + return bdev->md.md_offset + bdev->md.md_size_sect;
    + }
    +}
    +
    +/* Returns the number of 512 byte sectors of the device */
    +static inline sector_t drbd_get_capacity(struct block_device *bdev)
    +{
    + /* return bdev ? get_capacity(bdev->bd_disk) : 0; */
    + return bdev ? bdev->bd_inode->i_size >> 9 : 0;
    +}
    +
    +/* returns the capacity we announce to out peer.
    + * we clip ourselves at the various MAX_SECTORS, because if we don't,
    + * current implementation will oops sooner or later */
    +static inline sector_t drbd_get_max_capacity(struct drbd_backing_dev *bdev)
    +{
    + sector_t s;
    + switch (bdev->dc.meta_dev_idx) {
    + case DRBD_MD_INDEX_INTERNAL:
    + case DRBD_MD_INDEX_FLEX_INT:
    + s = drbd_get_capacity(bdev->backing_bdev)
    + ? min_t(sector_t, DRBD_MAX_SECTORS_FLEX,
    + drbd_md_first_sector(bdev))
    + : 0;
    + break;
    + case DRBD_MD_INDEX_FLEX_EXT:
    + s = min_t(sector_t, DRBD_MAX_SECTORS_FLEX,
    + drbd_get_capacity(bdev->backing_bdev));
    + /* clip at maximum size the meta device can support */
    + s = min_t(sector_t, s,
    + BM_EXT_TO_SECT(bdev->md.md_size_sect
    + - bdev->md.bm_offset));
    + break;
    + default:
    + s = min_t(sector_t, DRBD_MAX_SECTORS,
    + drbd_get_capacity(bdev->backing_bdev));
    + }
    + return s;
    +}
    +
    +/* returns the sector number of our meta data 'super' block */
    +static inline sector_t drbd_md_ss__(struct drbd_conf *mdev,
    + struct drbd_backing_dev *bdev)
    +{
    + switch (bdev->dc.meta_dev_idx) {
    + default: /* external, some index */
    + return MD_RESERVED_SECT * bdev->dc.meta_dev_idx;
    + case DRBD_MD_INDEX_INTERNAL:
    + /* with drbd08, internal meta data is always "flexible" */
    + case DRBD_MD_INDEX_FLEX_INT:
    + /* sizeof(struct md_on_disk_07) == 4k
    + * position: last 4k aligned block of 4k size */
    + if (!bdev->backing_bdev) {
    + if (__ratelimit(&drbd_ratelimit_state)) {
    + dev_err(DEV, "bdev->backing_bdev==NULL\n");
    + dump_stack();
    + }
    + return 0;
    + }
    + return (drbd_get_capacity(bdev->backing_bdev) & ~7ULL)
    + - MD_AL_OFFSET;
    + case DRBD_MD_INDEX_FLEX_EXT:
    + return 0;
    + }
    +}
    +
    +static inline void
    +_drbd_queue_work(struct drbd_work_queue *q, struct drbd_work *w)
    +{
    + list_add_tail(&w->list, &q->q);
    + up(&q->s);
    +}
    +
    +static inline void
    +drbd_queue_work_front(struct drbd_work_queue *q, struct drbd_work *w)
    +{
    + unsigned long flags;
    + spin_lock_irqsave(&q->q_lock, flags);
    + list_add(&w->list, &q->q);
    + up(&q->s); /* within the spinlock,
    + see comment near end of drbd_worker() */
    + spin_unlock_irqrestore(&q->q_lock, flags);
    +}
    +
    +static inline void
    +drbd_queue_work(struct drbd_work_queue *q, struct drbd_work *w)
    +{
    + unsigned long flags;
    + spin_lock_irqsave(&q->q_lock, flags);
    + list_add_tail(&w->list, &q->q);
    + up(&q->s); /* within the spinlock,
    + see comment near end of drbd_worker() */
    + spin_unlock_irqrestore(&q->q_lock, flags);
    +}
    +
    +static inline void wake_asender(struct drbd_conf *mdev)
    +{
    + if (test_bit(SIGNAL_ASENDER, &mdev->flags))
    + force_sig(DRBD_SIG, mdev->asender.task);
    +}
    +
    +static inline void request_ping(struct drbd_conf *mdev)
    +{
    + set_bit(SEND_PING, &mdev->flags);
    + wake_asender(mdev);
    +}
    +
    +static inline int drbd_send_short_cmd(struct drbd_conf *mdev,
    + enum drbd_packets cmd)
    +{
    + struct p_header h;
    + return drbd_send_cmd(mdev, USE_DATA_SOCKET, cmd, &h, sizeof(h));
    +}
    +
    +static inline int drbd_send_ping(struct drbd_conf *mdev)
    +{
    + struct p_header h;
    + return drbd_send_cmd(mdev, USE_META_SOCKET, P_PING, &h, sizeof(h));
    +}
    +
    +static inline int drbd_send_ping_ack(struct drbd_conf *mdev)
    +{
    + struct p_header h;
    + return drbd_send_cmd(mdev, USE_META_SOCKET, P_PING_ACK, &h, sizeof(h));
    +}
    +
    +static inline void drbd_thread_stop(struct drbd_thread *thi)
    +{
    + _drbd_thread_stop(thi, FALSE, TRUE);
    +}
    +
    +static inline void drbd_thread_stop_nowait(struct drbd_thread *thi)
    +{
    + _drbd_thread_stop(thi, FALSE, FALSE);
    +}
    +
    +static inline void drbd_thread_restart_nowait(struct drbd_thread *thi)
    +{
    + _drbd_thread_stop(thi, TRUE, FALSE);
    +}
    +
    +/* counts how many answer packets packets we expect from our peer,
    + * for either explicit application requests,
    + * or implicit barrier packets as necessary.
    + * increased:
    + * w_send_barrier
    + * _req_mod(req, queue_for_net_write or queue_for_net_read);
    + * it is much easier and equally valid to count what we queue for the
    + * worker, even before it actually was queued or send.
    + * (drbd_make_request_common; recovery path on read io-error)
    + * decreased:
    + * got_BarrierAck (respective tl_clear, tl_clear_barrier)
    + * _req_mod(req, data_received)
    + * [from receive_DataReply]
    + * _req_mod(req, write_acked_by_peer or recv_acked_by_peer or neg_acked)
    + * [from got_BlockAck (P_WRITE_ACK, P_RECV_ACK)]
    + * for some reason it is NOT decreased in got_NegAck,
    + * but in the resulting cleanup code from report_params.
    + * we should try to remember the reason for that...
    + * _req_mod(req, send_failed or send_canceled)
    + * _req_mod(req, connection_lost_while_pending)
    + * [from tl_clear_barrier]
    + */
    +static inline void inc_ap_pending(struct drbd_conf *mdev)
    +{
    + atomic_inc(&mdev->ap_pending_cnt);
    +}
    +
    +#define ERR_IF_CNT_IS_NEGATIVE(which) \
    + if (atomic_read(&mdev->which) < 0) \
    + dev_err(DEV, "in %s:%d: " #which " = %d < 0 !\n", \
    + __func__ , __LINE__ , \
    + atomic_read(&mdev->which))
    +
    +#define dec_ap_pending(mdev) do { \
    + typecheck(struct drbd_conf *, mdev); \
    + if (atomic_dec_and_test(&mdev->ap_pending_cnt)) \
    + wake_up(&mdev->misc_wait); \
    + ERR_IF_CNT_IS_NEGATIVE(ap_pending_cnt); } while (0)
    +
    +/* counts how many resync-related answers we still expect from the peer
    + * increase decrease
    + * C_SYNC_TARGET sends P_RS_DATA_REQUEST (and expects P_RS_DATA_REPLY)
    + * C_SYNC_SOURCE sends P_RS_DATA_REPLY (and expects P_WRITE_ACK whith ID_SYNCER)
    + * (or P_NEG_ACK with ID_SYNCER)
    + */
    +static inline void inc_rs_pending(struct drbd_conf *mdev)
    +{
    + atomic_inc(&mdev->rs_pending_cnt);
    +}
    +
    +#define dec_rs_pending(mdev) do { \
    + typecheck(struct drbd_conf *, mdev); \
    + atomic_dec(&mdev->rs_pending_cnt); \
    + ERR_IF_CNT_IS_NEGATIVE(rs_pending_cnt); } while (0)
    +
    +/* counts how many answers we still need to send to the peer.
    + * increased on
    + * receive_Data unless protocol A;
    + * we need to send a P_RECV_ACK (proto B)
    + * or P_WRITE_ACK (proto C)
    + * receive_RSDataReply (recv_resync_read) we need to send a P_WRITE_ACK
    + * receive_DataRequest (receive_RSDataRequest) we need to send back P_DATA
    + * receive_Barrier_* we need to send a P_BARRIER_ACK
    + */
    +static inline void inc_unacked(struct drbd_conf *mdev)
    +{
    + atomic_inc(&mdev->unacked_cnt);
    +}
    +
    +#define dec_unacked(mdev) do { \
    + typecheck(struct drbd_conf *, mdev); \
    + atomic_dec(&mdev->unacked_cnt); \
    + ERR_IF_CNT_IS_NEGATIVE(unacked_cnt); } while (0)
    +
    +#define sub_unacked(mdev, n) do { \
    + typecheck(struct drbd_conf *, mdev); \
    + atomic_sub(n, &mdev->unacked_cnt); \
    + ERR_IF_CNT_IS_NEGATIVE(unacked_cnt); } while (0)
    +
    +
    +static inline void dec_net(struct drbd_conf *mdev)
    +{
    + if (atomic_dec_and_test(&mdev->net_cnt))
    + wake_up(&mdev->misc_wait);
    +}
    +
    +/**
    + * inc_net: Returns TRUE when it is ok to access mdev->net_conf. You
    + * should call dec_net() when finished looking at mdev->net_conf.
    + */
    +static inline int inc_net(struct drbd_conf *mdev)
    +{
    + int have_net_conf;
    +
    + atomic_inc(&mdev->net_cnt);
    + have_net_conf = mdev->state.conn >= C_UNCONNECTED;
    + if (!have_net_conf)
    + dec_net(mdev);
    + return have_net_conf;
    +}
    +
    +/**
    + * inc_local: Returns TRUE when local IO is possible. If it returns
    + * TRUE you should call dec_local() after IO is completed.
    + */
    +#define inc_local_if_state(M,MINS) __cond_lock(local, _inc_local_if_state(M,MINS))
    +#define inc_local(M) __cond_lock(local, _inc_local_if_state(M,D_INCONSISTENT))
    +
    +static inline void dec_local(struct drbd_conf *mdev)
    +{
    + __release(local);
    + if (atomic_dec_and_test(&mdev->local_cnt))
    + wake_up(&mdev->misc_wait);
    + D_ASSERT(atomic_read(&mdev->local_cnt) >= 0);
    +}
    +
    +#ifndef __CHECKER__
    +static inline int _inc_local_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins)
    +{
    + int io_allowed;
    +
    + atomic_inc(&mdev->local_cnt);
    + io_allowed = (mdev->state.disk >= mins);
    + if (!io_allowed)
    + dec_local(mdev);
    + return io_allowed;
    +}
    +#else
    +extern int _inc_local_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins);
    +#endif
    +
    +/* you must have an "inc_local" reference */
    +static inline void drbd_get_syncer_progress(struct drbd_conf *mdev,
    + unsigned long *bits_left, unsigned int *per_mil_done)
    +{
    + /*
    + * this is to break it at compile time when we change that
    + * (we may feel 4TB maximum storage per drbd is not enough)
    + */
    + typecheck(unsigned long, mdev->rs_total);
    +
    + /* note: both rs_total and rs_left are in bits, i.e. in
    + * units of BM_BLOCK_SIZE.
    + * for the percentage, we don't care. */
    +
    + *bits_left = drbd_bm_total_weight(mdev) - mdev->rs_failed;
    + /* >> 10 to prevent overflow,
    + * +1 to prevent division by zero */
    + if (*bits_left > mdev->rs_total) {
    + /* doh. maybe a logic bug somewhere.
    + * may also be just a race condition
    + * between this and a disconnect during sync.
    + * for now, just prevent in-kernel buffer overflow.
    + */
    + smp_rmb();
    + dev_warn(DEV, "cs:%s rs_left=%lu > rs_total=%lu (rs_failed %lu)\n",
    + conns_to_name(mdev->state.conn),
    + *bits_left, mdev->rs_total, mdev->rs_failed);
    + *per_mil_done = 0;
    + } else {
    + /* make sure the calculation happens in long context */
    + unsigned long tmp = 1000UL -
    + (*bits_left >> 10)*1000UL
    + / ((mdev->rs_total >> 10) + 1UL);
    + *per_mil_done = tmp;
    + }
    +}
    +
    +
    +/* this throttles on-the-fly application requests
    + * according to max_buffers settings;
    + * maybe re-implement using semaphores? */
    +static inline int drbd_get_max_buffers(struct drbd_conf *mdev)
    +{
    + int mxb = 1000000; /* arbitrary limit on open requests */
    + if (inc_net(mdev)) {
    + mxb = mdev->net_conf->max_buffers;
    + dec_net(mdev);
    + }
    + return mxb;
    +}
    +
    +static inline int drbd_state_is_stable(union drbd_state s)
    +{
    +
    + /* DO NOT add a default clause, we want the compiler to warn us
    + * for any newly introduced state we may have forgotten to add here */
    +
    + switch ((enum drbd_conns)s.conn) {
    + /* new io only accepted when there is no connection, ... */
    + case C_STANDALONE:
    + case C_WF_CONNECTION:
    + /* ... or there is a well established connection. */
    + case C_CONNECTED:
    + case C_SYNC_SOURCE:
    + case C_SYNC_TARGET:
    + case C_VERIFY_S:
    + case C_VERIFY_T:
    + case C_PAUSED_SYNC_S:
    + case C_PAUSED_SYNC_T:
    + /* maybe stable, look at the disk state */
    + break;
    +
    + /* no new io accepted during tansitional states
    + * like handshake or teardown */
    + case C_DISCONNECTING:
    + case C_UNCONNECTED:
    + case C_TIMEOUT:
    + case C_BROKEN_PIPE:
    + case C_NETWORK_FAILURE:
    + case C_PROTOCOL_ERROR:
    + case C_TEAR_DOWN:
    + case C_WF_REPORT_PARAMS:
    + case C_STARTING_SYNC_S:
    + case C_STARTING_SYNC_T:
    + case C_WF_BITMAP_S:
    + case C_WF_BITMAP_T:
    + case C_WF_SYNC_UUID:
    + case C_MASK:
    + /* not "stable" */
    + return 0;
    + }
    +
    + switch ((enum drbd_disk_state)s.disk) {
    + case D_DISKLESS:
    + case D_INCONSISTENT:
    + case D_OUTDATED:
    + case D_CONSISTENT:
    + case D_UP_TO_DATE:
    + /* disk state is stable as well. */
    + break;
    +
    + /* no new io accepted during tansitional states */
    + case D_ATTACHING:
    + case D_FAILED:
    + case D_NEGOTIATING:
    + case D_UNKNOWN:
    + case D_MASK:
    + /* not "stable" */
    + return 0;
    + }
    +
    + return 1;
    +}
    +
    +static inline int __inc_ap_bio_cond(struct drbd_conf *mdev)
    +{
    + int mxb = drbd_get_max_buffers(mdev);
    +
    + if (mdev->state.susp)
    + return 0;
    + if (test_bit(SUSPEND_IO, &mdev->flags))
    + return 0;
    +
    + /* to avoid potential deadlock or bitmap corruption,
    + * in various places, we only allow new application io
    + * to start during "stable" states. */
    +
    + /* no new io accepted when attaching or detaching the disk */
    + if (!drbd_state_is_stable(mdev->state))
    + return 0;
    +
    + /* since some older kernels don't have atomic_add_unless,
    + * and we are within the spinlock anyways, we have this workaround. */
    + if (atomic_read(&mdev->ap_bio_cnt) > mxb)
    + return 0;
    + if (test_bit(BITMAP_IO, &mdev->flags))
    + return 0;
    + return 1;
    +}
    +
    +/* I'd like to use wait_event_lock_irq,
    + * but I'm not sure when it got introduced,
    + * and not sure when it has 3 or 4 arguments */
    +static inline void inc_ap_bio(struct drbd_conf *mdev, int one_or_two)
    +{
    + /* compare with after_state_ch,
    + * os.conn != C_WF_BITMAP_S && ns.conn == C_WF_BITMAP_S */
    + DEFINE_WAIT(wait);
    +
    + /* we wait here
    + * as long as the device is suspended
    + * until the bitmap is no longer on the fly during connection
    + * handshake as long as we would exeed the max_buffer limit.
    + *
    + * to avoid races with the reconnect code,
    + * we need to atomic_inc within the spinlock. */
    +
    + spin_lock_irq(&mdev->req_lock);
    + while (!__inc_ap_bio_cond(mdev)) {
    + prepare_to_wait(&mdev->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
    + spin_unlock_irq(&mdev->req_lock);
    + schedule();
    + finish_wait(&mdev->misc_wait, &wait);
    + spin_lock_irq(&mdev->req_lock);
    + }
    + atomic_add(one_or_two, &mdev->ap_bio_cnt);
    + spin_unlock_irq(&mdev->req_lock);
    +}
    +
    +static inline void dec_ap_bio(struct drbd_conf *mdev)
    +{
    + int mxb = drbd_get_max_buffers(mdev);
    + int ap_bio = atomic_dec_return(&mdev->ap_bio_cnt);
    +
    + D_ASSERT(ap_bio >= 0);
    + /* this currently does wake_up for every dec_ap_bio!
    + * maybe rather introduce some type of hysteresis?
    + * e.g. (ap_bio == mxb/2 || ap_bio == 0) ? */
    + if (ap_bio < mxb)
    + wake_up(&mdev->misc_wait);
    + if (ap_bio == 0 && test_bit(BITMAP_IO, &mdev->flags)) {
    + if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
    + drbd_queue_work(&mdev->data.work, &mdev->bm_io_work.w);
    + }
    +}
    +
    +static inline void drbd_set_ed_uuid(struct drbd_conf *mdev, u64 val)
    +{
    + mdev->ed_uuid = val;
    +}
    +
    +static inline int seq_cmp(u32 a, u32 b)
    +{
    + /* we assume wrap around at 32bit.
    + * for wrap around at 24bit (old atomic_t),
    + * we'd have to
    + * a <<= 8; b <<= 8;
    + */
    + return (s32)(a) - (s32)(b);
    +}
    +#define seq_lt(a, b) (seq_cmp((a), (b)) < 0)
    +#define seq_gt(a, b) (seq_cmp((a), (b)) > 0)
    +#define seq_ge(a, b) (seq_cmp((a), (b)) >= 0)
    +#define seq_le(a, b) (seq_cmp((a), (b)) <= 0)
    +/* CAUTION: please no side effects in arguments! */
    +#define seq_max(a, b) ((u32)(seq_gt((a), (b)) ? (a) : (b)))
    +
    +static inline void update_peer_seq(struct drbd_conf *mdev, unsigned int new_seq)
    +{
    + unsigned int m;
    + spin_lock(&mdev->peer_seq_lock);
    + m = seq_max(mdev->peer_seq, new_seq);
    + mdev->peer_seq = m;
    + spin_unlock(&mdev->peer_seq_lock);
    + if (m == new_seq)
    + wake_up(&mdev->seq_wait);
    +}
    +
    +static inline void drbd_update_congested(struct drbd_conf *mdev)
    +{
    + struct sock *sk = mdev->data.socket->sk;
    + if (sk->sk_wmem_queued > sk->sk_sndbuf * 4 / 5)
    + set_bit(NET_CONGESTED, &mdev->flags);
    +}
    +
    +static inline int drbd_queue_order_type(struct drbd_conf *mdev)
    +{
    + /* sorry, we currently have no working implementation
    + * of distributed TCQ stuff */
    +#ifndef QUEUE_ORDERED_NONE
    +#define QUEUE_ORDERED_NONE 0
    +#endif
    + return QUEUE_ORDERED_NONE;
    +}
    +
    +static inline void drbd_blk_run_queue(struct request_queue *q)
    +{
    + if (q && q->unplug_fn)
    + q->unplug_fn(q);
    +}
    +
    +static inline void drbd_kick_lo(struct drbd_conf *mdev)
    +{
    + if (inc_local(mdev)) {
    + drbd_blk_run_queue(bdev_get_queue(mdev->bc->backing_bdev));
    + dec_local(mdev);
    + }
    +}
    +
    +static inline void drbd_md_flush(struct drbd_conf *mdev)
    +{
    + int r;
    +
    + if (test_bit(MD_NO_BARRIER, &mdev->flags))
    + return;
    +
    + r = blkdev_issue_flush(mdev->bc->md_bdev, NULL);
    + if (r) {
    + set_bit(MD_NO_BARRIER, &mdev->flags);
    + dev_err(DEV, "meta data flush failed with status %d, disabling md-flushes\n", r);
    + }
    +}
    +
    +#endif
    diff --git a/drivers/block/drbd/drbd_wrappers.h b/drivers/block/drbd/drbd_wrappers.h
    new file mode 100644
    index 0000000..b7ce5ac
    --- /dev/null
    +++ b/drivers/block/drbd/drbd_wrappers.h
    @@ -0,0 +1,97 @@
    +#ifndef _DRBD_WRAPPERS_H
    +#define _DRBD_WRAPPERS_H
    +
    +#include <linux/ctype.h>
    +#include <linux/mm.h>
    +
    +
    +/* see get_sb_bdev and bd_claim */
    +extern char *drbd_sec_holder;
    +
    +static inline sector_t drbd_get_hardsect(struct block_device *bdev)
    +{
    + return bdev->bd_disk->queue->hardsect_size;
    +}
    +
    +/* sets the number of 512 byte sectors of our virtual device */
    +static inline void drbd_set_my_capacity(struct drbd_conf *mdev,
    + sector_t size)
    +{
    + /* set_capacity(mdev->this_bdev->bd_disk, size); */
    + set_capacity(mdev->vdisk, size);
    + mdev->this_bdev->bd_inode->i_size = (loff_t)size << 9;
    +}
    +
    +#define drbd_bio_uptodate(bio) bio_flagged(bio, BIO_UPTODATE)
    +
    +static inline int drbd_bio_has_active_page(struct bio *bio)
    +{
    + struct bio_vec *bvec;
    + int i;
    +
    + __bio_for_each_segment(bvec, bio, i, 0) {
    + if (page_count(bvec->bv_page) > 1)
    + return 1;
    + }
    +
    + return 0;
    +}
    +
    +/* bi_end_io handlers */
    +extern void drbd_md_io_complete(struct bio *bio, int error);
    +extern void drbd_endio_read_sec(struct bio *bio, int error);
    +extern void drbd_endio_write_sec(struct bio *bio, int error);
    +extern void drbd_endio_pri(struct bio *bio, int error);
    +
    +/*
    + * used to submit our private bio
    + */
    +static inline void drbd_generic_make_request(struct drbd_conf *mdev,
    + int fault_type, struct bio *bio)
    +{
    + __release(local);
    + if (!bio->bi_bdev) {
    + printk(KERN_ERR "drbd%d: drbd_generic_make_request: "
    + "bio->bi_bdev == NULL\n",
    + mdev_to_minor(mdev));
    + dump_stack();
    + bio_endio(bio, -ENODEV);
    + return;
    + }
    +
    + if (FAULT_ACTIVE(mdev, fault_type))
    + bio_endio(bio, -EIO);
    + else
    + generic_make_request(bio);
    +}
    +
    +static inline void drbd_plug_device(struct drbd_conf *mdev)
    +{
    + struct request_queue *q;
    + q = bdev_get_queue(mdev->this_bdev);
    +
    + spin_lock_irq(q->queue_lock);
    +
    +/* XXX the check on !blk_queue_plugged is redundant,
    + * implicitly checked in blk_plug_device */
    +
    + if (!blk_queue_plugged(q)) {
    + blk_plug_device(q);
    + del_timer(&q->unplug_timer);
    + /* unplugging should not happen automatically... */
    + }
    + spin_unlock_irq(q->queue_lock);
    +}
    +
    +static inline int drbd_crypto_is_hash(struct crypto_tfm *tfm)
    +{
    + return (crypto_tfm_alg_type(tfm) & CRYPTO_ALG_TYPE_HASH_MASK)
    + == CRYPTO_ALG_TYPE_HASH;
    +}
    +
    +#ifndef __CHECKER__
    +# undef __cond_lock
    +# define __cond_lock(x,c) (c)
    +#endif
    +
    +#endif

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