[PATCH 07/12] DRBD: main

[Philipp Reisner]

The DRBD state engine, and lots of other stuff, that does not have its own
source file.

---
diff -uNrp linux-2.6.29-rc8/drivers/block/drbd/drbd_main.c linux-2.6.29-rc8-drbd/drivers/block/drbd/drbd_main.c
--- linux-2.6.29-rc8/drivers/block/drbd/drbd_main.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.29-rc8-drbd/drivers/block/drbd/drbd_main.c	2009-03-23 11:25:50.348143000 +0100
@@ -0,0 +1,3846 @@
+/*
+-*- Linux-c -*-
+   drbd.c
+   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) 1999-2008, Philipp Reisner <philipp.reisner@xxxxxxxxxx>.
+   Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>.
+
+   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.
+
+ */
+
+#include <linux/autoconf.h>
+#include <linux/module.h>
+#include <linux/version.h>
+
+#include <asm/uaccess.h>
+#include <asm/types.h>
+#include <net/sock.h>
+#include <linux/ctype.h>
+#include <linux/smp_lock.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/proc_fs.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/drbd_config.h>
+#include <linux/memcontrol.h>
+#include <linux/mm_inline.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/reboot.h>
+#include <linux/notifier.h>
+#include <linux/kthread.h>
+
+#define __KERNEL_SYSCALLS__
+#include <linux/unistd.h>
+#include <linux/vmalloc.h>
+
+#include <linux/drbd.h>
+#include <linux/drbd_limits.h>
+#include "drbd_int.h"
+#include "drbd_req.h" /* only for _req_mod in tl_release and tl_clear */
+
+struct after_state_chg_work {
+	struct drbd_work w;
+	union drbd_state_t os;
+	union drbd_state_t ns;
+	enum chg_state_flags flags;
+	struct completion *done;
+};
+
+int drbdd_init(struct Drbd_thread *);
+int drbd_worker(struct Drbd_thread *);
+int drbd_asender(struct Drbd_thread *);
+
+int drbd_init(void);
+static int drbd_open(struct block_device *bdev, fmode_t mode);
+static int drbd_release(struct gendisk *gd, fmode_t mode);
+STATIC int w_after_state_ch(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+STATIC void after_state_ch(struct drbd_conf *mdev, union drbd_state_t os,
+			   union drbd_state_t ns, enum chg_state_flags flags);
+STATIC int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+STATIC void md_sync_timer_fn(unsigned long data);
+STATIC int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+
+MODULE_AUTHOR("Philipp Reisner <phil@xxxxxxxxxx>, "
+	      "Lars Ellenberg <lars@xxxxxxxxxx>");
+MODULE_DESCRIPTION("drbd - Distributed Replicated Block Device v" REL_VERSION);
+MODULE_LICENSE("GPL");
+MODULE_PARM_DESC(minor_count, "Maximum number of drbd devices (1-255)");
+MODULE_ALIAS_BLOCKDEV_MAJOR(DRBD_MAJOR);
+
+#include <linux/moduleparam.h>
+/* allow_open_on_secondary */
+MODULE_PARM_DESC(allow_oos, "DONT USE!");
+/* thanks to these macros, if compiled into the kernel (not-module),
+ * this becomes the boot parameter drbd.minor_count */
+module_param(minor_count, uint, 0444);
+module_param(allow_oos, bool, 0);
+module_param(cn_idx, uint, 0444);
+
+#ifdef DRBD_ENABLE_FAULTS
+int enable_faults;
+int fault_rate;
+static int fault_count;
+int fault_devs;
+/* bitmap of enabled faults */
+module_param(enable_faults, int, 0664);
+/* fault rate % value - applies to all enabled faults */
+module_param(fault_rate, int, 0664);
+/* count of faults inserted */
+module_param(fault_count, int, 0664);
+/* bitmap of devices to insert faults on */
+module_param(fault_devs, int, 0644);
+#endif
+
+/* module parameter, defined */
+unsigned int minor_count = 32;
+int allow_oos;
+unsigned int cn_idx = CN_IDX_DRBD;
+
+#ifdef ENABLE_DYNAMIC_TRACE
+int trace_type;		/* Bitmap of trace types to enable */
+int trace_level;	/* Current trace level */
+int trace_devs;		/* Bitmap of devices to trace */
+int proc_details;       /* Detail level in proc drbd*/
+
+module_param(trace_level, int, 0644);
+module_param(trace_type, int, 0644);
+module_param(trace_devs, int, 0644);
+module_param(proc_details, int, 0644);
+#endif
+
+/* Module parameter for setting the user mode helper program
+ * to run. Default is /sbin/drbdadm */
+char usermode_helper[80] = "/sbin/drbdadm";
+
+module_param_string(usermode_helper, usermode_helper, sizeof(usermode_helper), 0644);
+
+/* in 2.6.x, our device mapping and config info contains our virtual gendisks
+ * as member "struct gendisk *vdisk;"
+ */
+struct drbd_conf **minor_table;
+
+struct kmem_cache *drbd_request_cache;
+struct kmem_cache *drbd_ee_cache;
+mempool_t *drbd_request_mempool;
+mempool_t *drbd_ee_mempool;
+
+/* I do not use a standard mempool, because:
+   1) I want to hand out the preallocated objects first.
+   2) I want to be able to interrupt sleeping allocation with a signal.
+   Note: This is a single linked list, the next pointer is the private
+	 member of struct page.
+ */
+struct page *drbd_pp_pool;
+spinlock_t   drbd_pp_lock;
+int          drbd_pp_vacant;
+wait_queue_head_t drbd_pp_wait;
+
+STATIC struct block_device_operations drbd_ops = {
+	.owner =   THIS_MODULE,
+	.open =    drbd_open,
+	.release = drbd_release,
+};
+
+#define ARRY_SIZE(A) (sizeof(A)/sizeof(A[0]))
+
+#ifdef __CHECKER__
+/* When checking with sparse, and this is an inline function, sparse will
+   give tons of false positives. When this is a real functions sparse works.
+ */
+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) {
+		if (atomic_dec_and_test(&mdev->local_cnt))
+			wake_up(&mdev->misc_wait);
+	}
+	return io_allowed;
+}
+
+#endif
+
+/************************* The transfer log start */
+STATIC int tl_init(struct drbd_conf *mdev)
+{
+	struct drbd_barrier *b;
+
+	b = kmalloc(sizeof(struct drbd_barrier), GFP_KERNEL);
+	if (!b)
+		return 0;
+	INIT_LIST_HEAD(&b->requests);
+	INIT_LIST_HEAD(&b->w.list);
+	b->next = NULL;
+	b->br_number = 4711;
+	b->n_req = 0;
+	b->w.cb = NULL; /* if this is != NULL, we need to dec_ap_pending in tl_clear */
+
+	mdev->oldest_barrier = b;
+	mdev->newest_barrier = b;
+	INIT_LIST_HEAD(&mdev->out_of_sequence_requests);
+
+	mdev->tl_hash = NULL;
+	mdev->tl_hash_s = 0;
+
+	return 1;
+}
+
+STATIC void tl_cleanup(struct drbd_conf *mdev)
+{
+	D_ASSERT(mdev->oldest_barrier == mdev->newest_barrier);
+	D_ASSERT(list_empty(&mdev->out_of_sequence_requests));
+	kfree(mdev->oldest_barrier);
+	mdev->oldest_barrier = NULL;
+	kfree(mdev->unused_spare_barrier);
+	mdev->unused_spare_barrier = NULL;
+	kfree(mdev->tl_hash);
+	mdev->tl_hash = NULL;
+	mdev->tl_hash_s = 0;
+}
+
+/**
+ * _tl_add_barrier: Adds a barrier to the TL.
+ */
+void _tl_add_barrier(struct drbd_conf *mdev, struct drbd_barrier *new)
+{
+	struct drbd_barrier *newest_before;
+
+	INIT_LIST_HEAD(&new->requests);
+	INIT_LIST_HEAD(&new->w.list);
+	new->w.cb = NULL; /* if this is != NULL, we need to dec_ap_pending in tl_clear */
+	new->next = NULL;
+	new->n_req = 0;
+
+	newest_before = mdev->newest_barrier;
+	/* never send a barrier number == 0, because that is special-cased
+	 * when using TCQ for our write ordering code */
+	new->br_number = (newest_before->br_number+1) ?: 1;
+	if (mdev->newest_barrier != new) {
+		mdev->newest_barrier->next = new;
+		mdev->newest_barrier = new;
+	}
+}
+
+/* when we receive a barrier ack */
+void tl_release(struct drbd_conf *mdev, unsigned int barrier_nr,
+		       unsigned int set_size)
+{
+	struct drbd_barrier *b, *nob; /* next old barrier */
+	struct list_head *le, *tle;
+	struct drbd_request *r;
+
+	spin_lock_irq(&mdev->req_lock);
+
+	b = mdev->oldest_barrier;
+
+	/* first some paranoia code */
+	if (b == NULL) {
+		ERR("BAD! BarrierAck #%u received, but no epoch in tl!?\n",
+			barrier_nr);
+		goto bail;
+	}
+	if (b->br_number != barrier_nr) {
+		ERR("BAD! BarrierAck #%u received, expected #%u!\n",
+			barrier_nr, b->br_number);
+		goto bail;
+	}
+	if (b->n_req != set_size) {
+		ERR("BAD! BarrierAck #%u received with n_req=%u, expected n_req=%u!\n",
+			barrier_nr, set_size, b->n_req);
+		goto bail;
+	}
+
+	/* Clean up list of requests processed during current epoch */
+	list_for_each_safe(le, tle, &b->requests) {
+		r = list_entry(le, struct drbd_request, tl_requests);
+		_req_mod(r, barrier_acked, 0);
+	}
+	/* There could be requests on the list waiting for completion
+	   of the write to the local disk. To avoid corruptions of
+	   slab's data structures we have to remove the lists head.
+
+	   Also there could have been a barrier ack out of sequence, overtaking
+	   the write acks - which would be a but and violating write ordering.
+	   To not deadlock in case we lose connection while such requests are
+	   still pending, we need some way to find them for the
+	   _req_mode(connection_lost_while_pending).
+
+	   These have been list_move'd to the out_of_sequence_requests list in
+	   _req_mod(, barrier_acked,) above.
+	   */
+	list_del_init(&b->requests);
+
+	nob = b->next;
+	if (test_and_clear_bit(CREATE_BARRIER, &mdev->flags)) {
+		_tl_add_barrier(mdev, b);
+		if (nob)
+			mdev->oldest_barrier = nob;
+		/* if nob == NULL b was the only barrier, and becomes the new
+		   barrer. Threfore mdev->oldest_barrier points already to b */
+	} else {
+		D_ASSERT(nob != NULL);
+		mdev->oldest_barrier = nob;
+		kfree(b);
+	}
+
+	spin_unlock_irq(&mdev->req_lock);
+	dec_ap_pending(mdev);
+
+	return;
+
+bail:
+	spin_unlock_irq(&mdev->req_lock);
+	drbd_force_state(mdev, NS(conn, ProtocolError));
+}
+
+
+/* called by drbd_disconnect (exiting receiver thread)
+ * or from some after_state_ch */
+void tl_clear(struct drbd_conf *mdev)
+{
+	struct drbd_barrier *b, *tmp;
+	struct list_head *le, *tle;
+	struct drbd_request *r;
+	int new_initial_bnr = net_random();
+
+	spin_lock_irq(&mdev->req_lock);
+
+	b = mdev->oldest_barrier;
+	while (b) {
+		list_for_each_safe(le, tle, &b->requests) {
+			r = list_entry(le, struct drbd_request, tl_requests);
+			_req_mod(r, connection_lost_while_pending, 0);
+		}
+		tmp = b->next;
+
+		/* there could still be requests on that ring list,
+		 * in case local io is still pending */
+		list_del(&b->requests);
+
+		/* dec_ap_pending corresponding to queue_barrier.
+		 * the newest barrier may not have been queued yet,
+		 * in which case w.cb is still NULL. */
+		if (b->w.cb != NULL)
+			dec_ap_pending(mdev);
+
+		if (b == mdev->newest_barrier) {
+			/* recycle, but reinit! */
+			D_ASSERT(tmp == NULL);
+			INIT_LIST_HEAD(&b->requests);
+			INIT_LIST_HEAD(&b->w.list);
+			b->w.cb = NULL;
+			b->br_number = new_initial_bnr;
+			b->n_req = 0;
+
+			mdev->oldest_barrier = b;
+			break;
+		}
+		kfree(b);
+		b = tmp;
+	}
+
+	/* we expect this list to be empty. */
+	D_ASSERT(list_empty(&mdev->out_of_sequence_requests));
+
+	/* but just in case, clean it up anyways! */
+	list_for_each_safe(le, tle, &mdev->out_of_sequence_requests) {
+		r = list_entry(le, struct drbd_request, tl_requests);
+		_req_mod(r, connection_lost_while_pending, 0);
+	}
+
+	/* ensure bit indicating barrier is required is clear */
+	clear_bit(CREATE_BARRIER, &mdev->flags);
+
+	spin_unlock_irq(&mdev->req_lock);
+}
+
+/**
+ * drbd_io_error: Handles the on_io_error setting, should be called in the
+ * unlikely(!drbd_bio_uptodate(e->bio)) case from kernel thread context.
+ * See also drbd_chk_io_error
+ *
+ * NOTE: we set ourselves FAILED here if on_io_error is Detach or Panic OR
+ *	 if the forcedetach flag is set. This flag is set when failures
+ *	 occur writing the meta data portion of the disk as they are
+ *	 not recoverable.
+ */
+int drbd_io_error(struct drbd_conf *mdev, int forcedetach)
+{
+	enum io_error_handler eh;
+	unsigned long flags;
+	int send;
+	int ok = 1;
+
+	eh = PassOn;
+	if (inc_local_if_state(mdev, Failed)) {
+		eh = mdev->bc->dc.on_io_error;
+		dec_local(mdev);
+	}
+
+	if (!forcedetach && eh == PassOn)
+		return 1;
+
+	spin_lock_irqsave(&mdev->req_lock, flags);
+	send = (mdev->state.disk == Failed);
+	if (send)
+		_drbd_set_state(_NS(mdev, disk, Diskless), ChgStateHard, NULL);
+	spin_unlock_irqrestore(&mdev->req_lock, flags);
+
+	if (!send)
+		return ok;
+
+	if (mdev->state.conn >= Connected) {
+		ok = drbd_send_state(mdev);
+		if (ok)
+			drbd_WARN("Notified peer that my disk is broken.\n");
+		else
+			ERR("Sending state in drbd_io_error() failed\n");
+	}
+
+	/* Make sure we try to flush meta-data to disk - we come
+	 * in here because of a local disk error so it might fail
+	 * but we still need to try -- both because the error might
+	 * be in the data portion of the disk and because we need
+	 * to ensure the md-sync-timer is stopped if running. */
+	drbd_md_sync(mdev);
+
+	/* Releasing the backing device is done in after_state_ch() */
+
+	if (eh == CallIOEHelper)
+		drbd_khelper(mdev, "local-io-error");
+
+	return ok;
+}
+
+/**
+ * cl_wide_st_chg:
+ * Returns TRUE if this state change should be preformed as a cluster wide
+ * transaction. Of course it returns 0 as soon as the connection is lost.
+ */
+STATIC int cl_wide_st_chg(struct drbd_conf *mdev,
+			  union drbd_state_t os, union drbd_state_t ns)
+{
+	return (os.conn >= Connected && ns.conn >= Connected &&
+		 ((os.role != Primary && ns.role == Primary) ||
+		  (os.conn != StartingSyncT && ns.conn == StartingSyncT) ||
+		  (os.conn != StartingSyncS && ns.conn == StartingSyncS) ||
+		  (os.disk != Diskless && ns.disk == Diskless))) ||
+		(os.conn >= Connected && ns.conn == Disconnecting) ||
+		(os.conn == Connected && ns.conn == VerifyS);
+}
+
+int drbd_change_state(struct drbd_conf *mdev, enum chg_state_flags f,
+		      union drbd_state_t mask, union drbd_state_t val)
+{
+	unsigned long flags;
+	union drbd_state_t os, ns;
+	int rv;
+
+	spin_lock_irqsave(&mdev->req_lock, flags);
+	os = mdev->state;
+	ns.i = (os.i & ~mask.i) | val.i;
+	rv = _drbd_set_state(mdev, ns, f, NULL);
+	ns = mdev->state;
+	spin_unlock_irqrestore(&mdev->req_lock, flags);
+
+	return rv;
+}
+
+void drbd_force_state(struct drbd_conf *mdev,
+	union drbd_state_t mask, union drbd_state_t val)
+{
+	drbd_change_state(mdev, ChgStateHard, mask, val);
+}
+
+int is_valid_state(struct drbd_conf *mdev, union drbd_state_t ns);
+int is_valid_state_transition(struct drbd_conf *,
+	union drbd_state_t, union drbd_state_t);
+int drbd_send_state_req(struct drbd_conf *,
+	union drbd_state_t, union drbd_state_t);
+
+STATIC enum set_st_err _req_st_cond(struct drbd_conf *mdev,
+				    union drbd_state_t mask, union drbd_state_t val)
+{
+	union drbd_state_t os, ns;
+	unsigned long flags;
+	int rv;
+
+	if (test_and_clear_bit(CL_ST_CHG_SUCCESS, &mdev->flags))
+		return SS_CW_Success;
+
+	if (test_and_clear_bit(CL_ST_CHG_FAIL, &mdev->flags))
+		return SS_CW_FailedByPeer;
+
+	rv = 0;
+	spin_lock_irqsave(&mdev->req_lock, flags);
+	os = mdev->state;
+	ns.i = (os.i & ~mask.i) | val.i;
+	if (!cl_wide_st_chg(mdev, os, ns))
+		rv = SS_CW_NoNeed;
+	if (!rv) {
+		rv = is_valid_state(mdev, ns);
+		if (rv == SS_Success) {
+			rv = is_valid_state_transition(mdev, ns, os);
+			if (rv == SS_Success)
+				rv = 0; /* cont waiting, otherwise fail. */
+		}
+	}
+	spin_unlock_irqrestore(&mdev->req_lock, flags);
+
+	return rv;
+}
+
+/**
+ * _drbd_request_state:
+ * This function is the most gracefull way to change state. For some state
+ * transition this function even does a cluster wide transaction.
+ * It has a cousin named drbd_request_state(), which is always verbose.
+ */
+STATIC int drbd_req_state(struct drbd_conf *mdev,
+			  union drbd_state_t mask, union drbd_state_t val,
+			  enum chg_state_flags f)
+{
+	struct completion done;
+	unsigned long flags;
+	union drbd_state_t os, ns;
+	int rv;
+
+	init_completion(&done);
+
+	if (f & ChgSerialize)
+		mutex_lock(&mdev->state_mutex);
+
+	spin_lock_irqsave(&mdev->req_lock, flags);
+	os = mdev->state;
+	ns.i = (os.i & ~mask.i) | val.i;
+
+	if (cl_wide_st_chg(mdev, os, ns)) {
+		rv = is_valid_state(mdev, ns);
+		if (rv == SS_Success)
+			rv = is_valid_state_transition(mdev, ns, os);
+		spin_unlock_irqrestore(&mdev->req_lock, flags);
+
+		if (rv < SS_Success) {
+			if (f & ChgStateVerbose)
+				print_st_err(mdev, os, ns, rv);
+			goto abort;
+		}
+
+		drbd_state_lock(mdev);
+		if (!drbd_send_state_req(mdev, mask, val)) {
+			drbd_state_unlock(mdev);
+			rv = SS_CW_FailedByPeer;
+			if (f & ChgStateVerbose)
+				print_st_err(mdev, os, ns, rv);
+			goto abort;
+		}
+
+		wait_event(mdev->state_wait,
+			(rv = _req_st_cond(mdev, mask, val)));
+
+		if (rv < SS_Success) {
+			/* nearly dead code. */
+			drbd_state_unlock(mdev);
+			if (f & ChgStateVerbose)
+				print_st_err(mdev, os, ns, rv);
+			goto abort;
+		}
+		spin_lock_irqsave(&mdev->req_lock, flags);
+		os = mdev->state;
+		ns.i = (os.i & ~mask.i) | val.i;
+		rv = _drbd_set_state(mdev, ns, f, &done);
+		drbd_state_unlock(mdev);
+	} else {
+		rv = _drbd_set_state(mdev, ns, f, &done);
+	}
+
+	spin_unlock_irqrestore(&mdev->req_lock, flags);
+
+	if (f & ChgWaitComplete && rv == SS_Success) {
+		D_ASSERT(current != mdev->worker.task);
+		wait_for_completion(&done);
+	}
+
+abort:
+	if (f & ChgSerialize)
+		mutex_unlock(&mdev->state_mutex);
+
+	return rv;
+}
+
+/**
+ * _drbd_request_state:
+ * This function is the most gracefull way to change state. For some state
+ * transition this function even does a cluster wide transaction.
+ * It has a cousin named drbd_request_state(), which is always verbose.
+ */
+int _drbd_request_state(struct drbd_conf *mdev,	union drbd_state_t mask,
+			union drbd_state_t val,	enum chg_state_flags f)
+{
+	int rv;
+
+	wait_event(mdev->state_wait,
+		   (rv = drbd_req_state(mdev, mask, val, f)) != SS_InTransientState);
+
+	return rv;
+}
+
+STATIC void print_st(struct drbd_conf *mdev, char *name, union drbd_state_t ns)
+{
+	ERR(" %s = { cs:%s ro:%s/%s ds:%s/%s %c%c%c%c }\n",
+	    name,
+	    conns_to_name(ns.conn),
+	    roles_to_name(ns.role),
+	    roles_to_name(ns.peer),
+	    disks_to_name(ns.disk),
+	    disks_to_name(ns.pdsk),
+	    ns.susp ? 's' : 'r',
+	    ns.aftr_isp ? 'a' : '-',
+	    ns.peer_isp ? 'p' : '-',
+	    ns.user_isp ? 'u' : '-'
+	    );
+}
+
+void print_st_err(struct drbd_conf *mdev,
+	union drbd_state_t os, union drbd_state_t ns, int err)
+{
+	if (err == SS_InTransientState)
+		return;
+	ERR("State change failed: %s\n", set_st_err_name(err));
+	print_st(mdev, " state", os);
+	print_st(mdev, "wanted", ns);
+}
+
+
+#define peers_to_name roles_to_name
+#define pdsks_to_name disks_to_name
+
+#define susps_to_name(A)     ((A) ? "1" : "0")
+#define aftr_isps_to_name(A) ((A) ? "1" : "0")
+#define peer_isps_to_name(A) ((A) ? "1" : "0")
+#define user_isps_to_name(A) ((A) ? "1" : "0")
+
+#define PSC(A) \
+	({ if (ns.A != os.A) { \
+		pbp += sprintf(pbp, #A "( %s -> %s ) ", \
+			      A##s_to_name(os.A), \
+			      A##s_to_name(ns.A)); \
+	} })
+
+int is_valid_state(struct drbd_conf *mdev, union drbd_state_t ns)
+{
+	/* See drbd_state_sw_errors in drbd_strings.c */
+
+	enum fencing_policy fp;
+	int rv = SS_Success;
+
+	fp = DontCare;
+	if (inc_local(mdev)) {
+		fp = mdev->bc->dc.fencing;
+		dec_local(mdev);
+	}
+
+	if (inc_net(mdev)) {
+		if (!mdev->net_conf->two_primaries &&
+		    ns.role == Primary && ns.peer == Primary)
+			rv = SS_TwoPrimaries;
+		dec_net(mdev);
+	}
+
+	if (rv <= 0)
+		/* already found a reason to abort */;
+	else if (ns.role == Secondary && mdev->open_cnt)
+		rv = SS_DeviceInUse;
+
+	else if (ns.role == Primary && ns.conn < Connected && ns.disk < UpToDate)
+		rv = SS_NoUpToDateDisk;
+
+	else if (fp >= Resource &&
+		 ns.role == Primary && ns.conn < Connected && ns.pdsk >= DUnknown)
+		rv = SS_PrimaryNOP;
+
+	else if (ns.role == Primary && ns.disk <= Inconsistent && ns.pdsk <= Inconsistent)
+		rv = SS_NoUpToDateDisk;
+
+	else if (ns.conn > Connected && ns.disk < UpToDate && ns.pdsk < UpToDate)
+		rv = SS_BothInconsistent;
+
+	else if (ns.conn > Connected && (ns.disk == Diskless || ns.pdsk == Diskless))
+		rv = SS_SyncingDiskless;
+
+	else if ((ns.conn == Connected ||
+		  ns.conn == WFBitMapS ||
+		  ns.conn == SyncSource ||
+		  ns.conn == PausedSyncS) &&
+		  ns.disk == Outdated)
+		rv = SS_ConnectedOutdates;
+
+	else if ((ns.conn == VerifyS || ns.conn == VerifyT) &&
+		 (mdev->sync_conf.verify_alg[0] == 0))
+		rv = SS_NoVerifyAlg;
+
+	else if ((ns.conn == VerifyS || ns.conn == VerifyT) &&
+		  mdev->agreed_pro_version < 88)
+		rv = SS_NotSupported;
+
+	return rv;
+}
+
+int is_valid_state_transition(struct drbd_conf *mdev,
+	union drbd_state_t ns, union drbd_state_t os)
+{
+	int rv = SS_Success;
+
+	if ((ns.conn == StartingSyncT || ns.conn == StartingSyncS) &&
+	    os.conn > Connected)
+		rv = SS_ResyncRunning;
+
+	if (ns.conn == Disconnecting && os.conn == StandAlone)
+		rv = SS_AlreadyStandAlone;
+
+	if (ns.disk > Attaching && os.disk == Diskless)
+		rv = SS_IsDiskLess;
+
+	if (ns.conn == WFConnection && os.conn < Unconnected)
+		rv = SS_NoNetConfig;
+
+	if (ns.disk == Outdated && os.disk < Outdated && os.disk != Attaching)
+		rv = SS_LowerThanOutdated;
+
+	if (ns.conn == Disconnecting && os.conn == Unconnected)
+		rv = SS_InTransientState;
+
+	if (ns.conn == os.conn && ns.conn == WFReportParams)
+		rv = SS_InTransientState;
+
+	if ((ns.conn == VerifyS || ns.conn == VerifyT) && os.conn < Connected)
+		rv = SS_NeedConnection;
+
+	if ((ns.conn == VerifyS || ns.conn == VerifyT) &&
+	    ns.conn != os.conn && os.conn > Connected)
+		rv = SS_ResyncRunning;
+
+	if ((ns.conn == StartingSyncS || ns.conn == StartingSyncT) &&
+	    os.conn < Connected)
+		rv = SS_NeedConnection;
+
+	return rv;
+}
+
+int _drbd_set_state(struct drbd_conf *mdev,
+		    union drbd_state_t ns, enum chg_state_flags flags,
+		    struct completion *done)
+{
+	union drbd_state_t os;
+	int rv = SS_Success;
+	int warn_sync_abort = 0;
+	enum fencing_policy fp;
+	struct after_state_chg_work *ascw;
+
+
+	os = mdev->state;
+
+	fp = DontCare;
+	if (inc_local(mdev)) {
+		fp = mdev->bc->dc.fencing;
+		dec_local(mdev);
+	}
+
+	/* Early state sanitising. */
+
+	/* Dissalow Network errors to configure a device's network part */
+	if ((ns.conn >= Timeout && ns.conn <= TearDown) &&
+	    os.conn <= Disconnecting)
+		ns.conn = os.conn;
+
+	/* After a network error (+TearDown) only Unconnected or Disconnecting can follow */
+	if (os.conn >= Timeout && os.conn <= TearDown &&
+	    ns.conn != Unconnected && ns.conn != Disconnecting)
+		ns.conn = os.conn;
+
+	/* After Disconnecting only StandAlone may follow */
+	if (os.conn == Disconnecting && ns.conn != StandAlone)
+		ns.conn = os.conn;
+
+	if (ns.conn < Connected) {
+		ns.peer_isp = 0;
+		ns.peer = Unknown;
+		if (ns.pdsk > DUnknown || ns.pdsk < Inconsistent)
+			ns.pdsk = DUnknown;
+	}
+
+	if (ns.conn <= Disconnecting && ns.disk == Diskless)
+		ns.pdsk = DUnknown;
+
+	if (os.conn > Connected && ns.conn > Connected &&
+	    (ns.disk <= Failed || ns.pdsk <= Failed)) {
+		warn_sync_abort = 1;
+		ns.conn = Connected;
+	}
+
+	if (ns.conn >= Connected &&
+	    ((ns.disk == Consistent || ns.disk == Outdated) ||
+	     (ns.disk == Negotiating && ns.conn == WFBitMapT))) {
+		switch (ns.conn) {
+		case WFBitMapT:
+		case PausedSyncT:
+			ns.disk = Outdated;
+			break;
+		case Connected:
+		case WFBitMapS:
+		case SyncSource:
+		case PausedSyncS:
+			ns.disk = UpToDate;
+			break;
+		case SyncTarget:
+			ns.disk = Inconsistent;
+			drbd_WARN("Implicit set disk state Inconsistent!\n");
+			break;
+		}
+		if (os.disk == Outdated && ns.disk == UpToDate)
+			drbd_WARN("Implicit set disk from Outdate to UpToDate\n");
+	}
+
+	if (ns.conn >= Connected &&
+	    (ns.pdsk == Consistent || ns.pdsk == Outdated)) {
+		switch (ns.conn) {
+		case Connected:
+		case WFBitMapT:
+		case PausedSyncT:
+		case SyncTarget:
+			ns.pdsk = UpToDate;
+			break;
+		case WFBitMapS:
+		case PausedSyncS:
+			ns.pdsk = Outdated;
+			break;
+		case SyncSource:
+			ns.pdsk = Inconsistent;
+			drbd_WARN("Implicit set pdsk Inconsistent!\n");
+			break;
+		}
+		if (os.pdsk == Outdated && ns.pdsk == UpToDate)
+			drbd_WARN("Implicit set pdsk from Outdate to UpToDate\n");
+	}
+
+	/* Connection breaks down before we finished "Negotiating" */
+	if (ns.conn < Connected && ns.disk == Negotiating &&
+	    inc_local_if_state(mdev, Negotiating)) {
+		if (mdev->ed_uuid == mdev->bc->md.uuid[Current]) {
+			ns.disk = mdev->new_state_tmp.disk;
+			ns.pdsk = mdev->new_state_tmp.pdsk;
+		} else {
+			ALERT("Connection lost while negotiating, no data!\n");
+			ns.disk = Diskless;
+			ns.pdsk = DUnknown;
+		}
+		dec_local(mdev);
+	}
+
+	if (fp == Stonith &&
+	    (ns.role == Primary &&
+	     ns.conn < Connected &&
+	     ns.pdsk > Outdated))
+			ns.susp = 1;
+
+	if (ns.aftr_isp || ns.peer_isp || ns.user_isp) {
+		if (ns.conn == SyncSource)
+			ns.conn = PausedSyncS;
+		if (ns.conn == SyncTarget)
+			ns.conn = PausedSyncT;
+	} else {
+		if (ns.conn == PausedSyncS)
+			ns.conn = SyncSource;
+		if (ns.conn == PausedSyncT)
+			ns.conn = SyncTarget;
+	}
+
+	if (ns.i == os.i)
+		return SS_NothingToDo;
+
+	if (!(flags & ChgStateHard)) {
+		/*  pre-state-change checks ; only look at ns  */
+		/* See drbd_state_sw_errors in drbd_strings.c */
+
+		rv = is_valid_state(mdev, ns);
+		if (rv < SS_Success) {
+			/* If the old state was illegal as well, then let
+			   this happen...*/
+
+			if (is_valid_state(mdev, os) == rv) {
+				ERR("Considering state change from bad state. "
+				    "Error would be: '%s'\n",
+				    set_st_err_name(rv));
+				print_st(mdev, "old", os);
+				print_st(mdev, "new", ns);
+				rv = is_valid_state_transition(mdev, ns, os);
+			}
+		} else
+			rv = is_valid_state_transition(mdev, ns, os);
+	}
+
+	if (rv < SS_Success) {
+		if (flags & ChgStateVerbose)
+			print_st_err(mdev, os, ns, rv);
+		return rv;
+	}
+
+	if (warn_sync_abort)
+		drbd_WARN("Resync aborted.\n");
+
+	{
+		char *pbp, pb[300];
+		pbp = pb;
+		*pbp = 0;
+		PSC(role);
+		PSC(peer);
+		PSC(conn);
+		PSC(disk);
+		PSC(pdsk);
+		PSC(susp);
+		PSC(aftr_isp);
+		PSC(peer_isp);
+		PSC(user_isp);
+		INFO("%s\n", pb);
+	}
+
+	mdev->state.i = ns.i;
+	wake_up(&mdev->misc_wait);
+	wake_up(&mdev->state_wait);
+
+	/**   post-state-change actions   **/
+	if (os.conn >= SyncSource   && ns.conn <= Connected) {
+		set_bit(STOP_SYNC_TIMER, &mdev->flags);
+		mod_timer(&mdev->resync_timer, jiffies);
+	}
+
+	if ((os.conn == PausedSyncT || os.conn == PausedSyncS) &&
+	    (ns.conn == SyncTarget  || ns.conn == SyncSource)) {
+		INFO("Syncer continues.\n");
+		mdev->rs_paused += (long)jiffies-(long)mdev->rs_mark_time;
+		if (ns.conn == SyncTarget) {
+			if (!test_and_clear_bit(STOP_SYNC_TIMER, &mdev->flags))
+				mod_timer(&mdev->resync_timer, jiffies);
+			/* This if (!test_bit) is only needed for the case
+			   that a device that has ceased to used its timer,
+			   i.e. it is already in drbd_resync_finished() gets
+			   paused and resumed. */
+		}
+	}
+
+	if ((os.conn == SyncTarget  || os.conn == SyncSource) &&
+	    (ns.conn == PausedSyncT || ns.conn == PausedSyncS)) {
+		INFO("Resync suspended\n");
+		mdev->rs_mark_time = jiffies;
+		if (ns.conn == PausedSyncT)
+			set_bit(STOP_SYNC_TIMER, &mdev->flags);
+	}
+
+	if (os.conn == Connected &&
+	    (ns.conn == VerifyS || ns.conn == VerifyT)) {
+		mdev->ov_position = 0;
+		mdev->ov_left  =
+		mdev->rs_total =
+		mdev->rs_mark_left = drbd_bm_bits(mdev);
+		mdev->rs_start     =
+		mdev->rs_mark_time = jiffies;
+		mdev->ov_last_oos_size = 0;
+		mdev->ov_last_oos_start = 0;
+
+		if (ns.conn == VerifyS)
+			mod_timer(&mdev->resync_timer, jiffies);
+	}
+
+	if (inc_local(mdev)) {
+		u32 mdf = mdev->bc->md.flags & ~(MDF_Consistent|MDF_PrimaryInd|
+						 MDF_ConnectedInd|MDF_WasUpToDate|
+						 MDF_PeerOutDated|MDF_CrashedPrimary);
+
+		if (test_bit(CRASHED_PRIMARY, &mdev->flags))
+			mdf |= MDF_CrashedPrimary;
+		if (mdev->state.role == Primary ||
+		    (mdev->state.pdsk < Inconsistent && mdev->state.peer == Primary))
+			mdf |= MDF_PrimaryInd;
+		if (mdev->state.conn > WFReportParams)
+			mdf |= MDF_ConnectedInd;
+		if (mdev->state.disk > Inconsistent)
+			mdf |= MDF_Consistent;
+		if (mdev->state.disk > Outdated)
+			mdf |= MDF_WasUpToDate;
+		if (mdev->state.pdsk <= Outdated && mdev->state.pdsk >= Inconsistent)
+			mdf |= MDF_PeerOutDated;
+		if (mdf != mdev->bc->md.flags) {
+			mdev->bc->md.flags = mdf;
+			drbd_md_mark_dirty(mdev);
+		}
+		if (os.disk < Consistent && ns.disk >= Consistent)
+			drbd_set_ed_uuid(mdev, mdev->bc->md.uuid[Current]);
+		dec_local(mdev);
+	}
+
+	/* Peer was forced UpToDate & Primary, consider to resync */
+	if (os.disk == Inconsistent && os.pdsk == Inconsistent &&
+	    os.peer == Secondary && ns.peer == Primary)
+		set_bit(CONSIDER_RESYNC, &mdev->flags);
+
+	/* Receiver should clean up itself */
+	if (os.conn != Disconnecting && ns.conn == Disconnecting)
+		drbd_thread_stop_nowait(&mdev->receiver);
+
+	/* Now the receiver finished cleaning up itself, it should die */
+	if (os.conn != StandAlone && ns.conn == StandAlone)
+		drbd_thread_stop_nowait(&mdev->receiver);
+
+	/* Upon network failure, we need to restart the receiver. */
+	if (os.conn > TearDown &&
+	    ns.conn <= TearDown && ns.conn >= Timeout)
+		drbd_thread_restart_nowait(&mdev->receiver);
+
+	ascw = kmalloc(sizeof(*ascw), GFP_ATOMIC);
+	if (ascw) {
+		ascw->os = os;
+		ascw->ns = ns;
+		ascw->flags = flags;
+		ascw->w.cb = w_after_state_ch;
+		ascw->done = done;
+		drbd_queue_work(&mdev->data.work, &ascw->w);
+	} else {
+		drbd_WARN("Could not kmalloc an ascw\n");
+	}
+
+	return rv;
+}
+
+STATIC int w_after_state_ch(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+{
+	struct after_state_chg_work *ascw;
+
+	ascw = (struct after_state_chg_work *) w;
+	after_state_ch(mdev, ascw->os, ascw->ns, ascw->flags);
+	if (ascw->flags & ChgWaitComplete) {
+		D_ASSERT(ascw->done != NULL);
+		complete(ascw->done);
+	}
+	kfree(ascw);
+
+	return 1;
+}
+
+static void abw_start_sync(struct drbd_conf *mdev, int rv)
+{
+	if (rv) {
+		ERR("Writing the bitmap failed not starting resync.\n");
+		_drbd_request_state(mdev, NS(conn, Connected), ChgStateVerbose);
+		return;
+	}
+
+	switch (mdev->state.conn) {
+	case StartingSyncT:
+		_drbd_request_state(mdev, NS(conn, WFSyncUUID), ChgStateVerbose);
+		break;
+	case StartingSyncS:
+		drbd_start_resync(mdev, SyncSource);
+		break;
+	}
+}
+
+STATIC void after_state_ch(struct drbd_conf *mdev, union drbd_state_t os,
+			   union drbd_state_t ns, enum chg_state_flags flags)
+{
+	enum fencing_policy fp;
+
+	if (os.conn != Connected && ns.conn == Connected) {
+		clear_bit(CRASHED_PRIMARY, &mdev->flags);
+		if (mdev->p_uuid)
+			mdev->p_uuid[UUID_FLAGS] &= ~((u64)2);
+	}
+
+	fp = DontCare;
+	if (inc_local(mdev)) {
+		fp = mdev->bc->dc.fencing;
+		dec_local(mdev);
+	}
+
+	/* Inform userspace about the change... */
+	drbd_bcast_state(mdev, ns);
+
+	if (!(os.role == Primary && os.disk < UpToDate && os.pdsk < UpToDate) &&
+	    (ns.role == Primary && ns.disk < UpToDate && ns.pdsk < UpToDate))
+		drbd_khelper(mdev, "pri-on-incon-degr");
+
+	/* Here we have the actions that are performed after a
+	   state change. This function might sleep */
+
+	if (fp == Stonith && ns.susp) {
+		/* case1: The outdate peer handler is successfull:
+		 * case2: The connection was established again: */
+		if ((os.pdsk > Outdated  && ns.pdsk <= Outdated) ||
+		    (os.conn < Connected && ns.conn >= Connected)) {
+			tl_clear(mdev);
+			spin_lock_irq(&mdev->req_lock);
+			_drbd_set_state(_NS(mdev, susp, 0), ChgStateVerbose, NULL);
+			spin_unlock_irq(&mdev->req_lock);
+		}
+	}
+	/* Do not change the order of the if above and the two below... */
+	if (os.pdsk == Diskless && ns.pdsk > Diskless) {      /* attach on the peer */
+		drbd_send_uuids(mdev);
+		drbd_send_state(mdev);
+	}
+	if (os.conn != WFBitMapS && ns.conn == WFBitMapS)
+		drbd_queue_bitmap_io(mdev, &drbd_send_bitmap, NULL, "send_bitmap (WFBitMapS)");
+
+	/* Lost contact to peer's copy of the data */
+	if ((os.pdsk >= Inconsistent &&
+	     os.pdsk != DUnknown &&
+	     os.pdsk != Outdated)
+	&&  (ns.pdsk < Inconsistent ||
+	     ns.pdsk == DUnknown ||
+	     ns.pdsk == Outdated)) {
+		kfree(mdev->p_uuid);
+		mdev->p_uuid = NULL;
+		if (inc_local(mdev)) {
+			if ((ns.role == Primary || ns.peer == Primary) &&
+			    mdev->bc->md.uuid[Bitmap] == 0 && ns.disk >= UpToDate) {
+				drbd_uuid_new_current(mdev);
+				drbd_send_uuids(mdev);
+			}
+			dec_local(mdev);
+		}
+	}
+
+	if (ns.pdsk < Inconsistent && inc_local(mdev)) {
+		if (ns.peer == Primary && mdev->bc->md.uuid[Bitmap] == 0)
+			drbd_uuid_new_current(mdev);
+
+		/* Diskless Peer becomes secondary */
+		if (os.peer == Primary && ns.peer == Secondary)
+			drbd_al_to_on_disk_bm(mdev);
+		dec_local(mdev);
+	}
+
+	/* Last part of the attaching process ... */
+	if (ns.conn >= Connected &&
+	    os.disk == Attaching && ns.disk == Negotiating) {
+		kfree(mdev->p_uuid); /* We expect to receive up-to-date UUIDs soon. */
+		mdev->p_uuid = NULL; /* ...to not use the old ones in the mean time */
+		drbd_send_sizes(mdev);  /* to start sync... */
+		drbd_send_uuids(mdev);
+		drbd_send_state(mdev);
+	}
+
+	/* We want to pause/continue resync, tell peer. */
+	if (ns.conn >= Connected &&
+	     ((os.aftr_isp != ns.aftr_isp) ||
+	      (os.user_isp != ns.user_isp)))
+		drbd_send_state(mdev);
+
+	/* In case one of the isp bits got set, suspend other devices. */
+	if ((!os.aftr_isp && !os.peer_isp && !os.user_isp) &&
+	    (ns.aftr_isp || ns.peer_isp || ns.user_isp))
+		suspend_other_sg(mdev);
+
+	/* Make sure the peer gets informed about eventual state
+	   changes (ISP bits) while we were in WFReportParams. */
+	if (os.conn == WFReportParams && ns.conn >= Connected)
+		drbd_send_state(mdev);
+
+	/* We are in the progress to start a full sync... */
+	if ((os.conn != StartingSyncT && ns.conn == StartingSyncT) ||
+	    (os.conn != StartingSyncS && ns.conn == StartingSyncS))
+		drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, &abw_start_sync, "set_n_write from StartingSync");
+
+	/* We are invalidating our self... */
+	if (os.conn < Connected && ns.conn < Connected &&
+	    os.disk > Inconsistent && ns.disk == Inconsistent)
+		drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, NULL, "set_n_write from invalidate");
+
+	if (os.disk > Diskless && ns.disk == Diskless) {
+		/* since inc_local() only works as long as disk>=Inconsistent,
+		   and it is Diskless here, local_cnt can only go down, it can
+		   not increase... It will reach zero */
+		wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
+
+		lc_free(mdev->resync);
+		mdev->resync = NULL;
+		lc_free(mdev->act_log);
+		mdev->act_log = NULL;
+		__no_warn(local, drbd_free_bc(mdev->bc););
+		wmb(); /* see begin of drbd_nl_disk_conf() */
+		__no_warn(local, mdev->bc = NULL;);
+	}
+
+	/* Disks got bigger while they were detached */
+	if (ns.disk > Negotiating && ns.pdsk > Negotiating &&
+	    test_and_clear_bit(RESYNC_AFTER_NEG, &mdev->flags)) {
+		if (ns.conn == Connected)
+			resync_after_online_grow(mdev);
+	}
+
+	/* A resync finished or aborted, wake paused devices... */
+	if ((os.conn > Connected && ns.conn <= Connected) ||
+	    (os.peer_isp && !ns.peer_isp) ||
+	    (os.user_isp && !ns.user_isp))
+		resume_next_sg(mdev);
+
+	/* Upon network connection, we need to start the received */
+	if (os.conn == StandAlone && ns.conn == Unconnected)
+		drbd_thread_start(&mdev->receiver);
+
+	/* Terminate worker thread if we are unconfigured - it will be
+	   restarted as needed... */
+	if (ns.disk == Diskless && ns.conn == StandAlone && ns.role == Secondary)
+		drbd_thread_stop_nowait(&mdev->worker);
+
+	drbd_md_sync(mdev);
+}
+
+
+STATIC int drbd_thread_setup(void *arg)
+{
+	struct Drbd_thread *thi = (struct Drbd_thread *) arg;
+	struct drbd_conf *mdev = thi->mdev;
+	int retval;
+
+restart:
+	retval = thi->function(thi);
+
+	spin_lock(&thi->t_lock);
+
+	/* if the receiver has been "Exiting", the last thing it did
+	 * was set the conn state to "StandAlone",
+	 * if now a re-connect request comes in, conn state goes Unconnected,
+	 * and receiver thread will be "started".
+	 * drbd_thread_start needs to set "Restarting" in that case.
+	 * t_state check and assignement needs to be within the same spinlock,
+	 * so either thread_start sees Exiting, and can remap to Restarting,
+	 * or thread_start see None, and can proceed as normal.
+	 */
+
+	if (thi->t_state == Restarting) {
+		INFO("Restarting %s\n", current->comm);
+		thi->t_state = Running;
+		spin_unlock(&thi->t_lock);
+		goto restart;
+	}
+
+	thi->task = NULL;
+	thi->t_state = None;
+	smp_mb();
+
+	spin_unlock(&thi->t_lock);
+
+	INFO("Terminating %s\n", current->comm);
+
+	/* Release mod reference taken when thread was started */
+	module_put(THIS_MODULE);
+	return retval;
+}
+
+STATIC void drbd_thread_init(struct drbd_conf *mdev, struct Drbd_thread *thi,
+		      int (*func) (struct Drbd_thread *))
+{
+	spin_lock_init(&thi->t_lock);
+	thi->task    = NULL;
+	thi->t_state = None;
+	thi->function = func;
+	thi->mdev = mdev;
+}
+
+int drbd_thread_start(struct Drbd_thread *thi)
+{
+	struct drbd_conf *mdev = thi->mdev;
+	struct task_struct *nt;
+	const char *me =
+		thi == &mdev->receiver ? "receiver" :
+		thi == &mdev->asender  ? "asender"  :
+		thi == &mdev->worker   ? "worker"   : "NONSENSE";
+
+	spin_lock(&thi->t_lock);
+	switch (thi->t_state) {
+	case None:
+		INFO("Starting %s thread (from %s [%d])\n",
+				me, current->comm, current->pid);
+
+		/* Get ref on module for thread - this is released when thread exits */
+		if (!try_module_get(THIS_MODULE)) {
+			ERR("Failed to get module reference in drbd_thread_start\n");
+			spin_unlock(&thi->t_lock);
+			return FALSE;
+		}
+
+		D_ASSERT(thi->task == NULL);
+		thi->reset_cpu_mask = 1;
+		thi->t_state = Running;
+		spin_unlock(&thi->t_lock);
+		flush_signals(current); /* otherw. may get -ERESTARTNOINTR */
+
+		nt = kthread_create(drbd_thread_setup, (void *) thi,
+				    "drbd%d_%s", mdev_to_minor(mdev), me);
+
+		if (IS_ERR(nt)) {
+			ERR("Couldn't start thread\n");
+
+			module_put(THIS_MODULE);
+			return FALSE;
+		}
+		spin_lock(&thi->t_lock);
+		thi->task = nt;
+		thi->t_state = Running;
+		spin_unlock(&thi->t_lock);
+		wake_up_process(nt);
+		break;
+	case Exiting:
+		thi->t_state = Restarting;
+		INFO("Restarting %s thread (from %s [%d])\n",
+				me, current->comm, current->pid);
+	case Running:
+	case Restarting:
+	default:
+		spin_unlock(&thi->t_lock);
+		break;
+	}
+
+	return TRUE;
+}
+
+
+void _drbd_thread_stop(struct Drbd_thread *thi, int restart, int wait)
+{
+	enum Drbd_thread_state ns = restart ? Restarting : Exiting;
+	struct task_struct *nt = NULL;
+
+	spin_lock(&thi->t_lock);
+
+	if (thi->t_state == None) {
+		spin_unlock(&thi->t_lock);
+		if (restart)
+			drbd_thread_start(thi);
+		return;
+	}
+
+	if (thi->t_state != ns) {
+		if (thi->task == NULL) {
+			spin_unlock(&thi->t_lock);
+			return;
+		}
+
+		thi->t_state = ns;
+		smp_mb();
+		if (thi->task != current)
+			force_sig(DRBD_SIGKILL, thi->task);
+
+	}
+
+	if (wait)
+		nt = thi->task;
+
+	spin_unlock(&thi->t_lock);
+
+	if (nt)
+		kthread_stop(nt);
+
+}
+
+#ifdef CONFIG_SMP
+/**
+ * drbd_calc_cpu_mask: Generates CPU masks, sprad over all CPUs.
+ * Forces all threads of a device onto the same CPU. This is benificial for
+ * DRBD's performance. May be overwritten by user's configuration.
+ */
+cpumask_t drbd_calc_cpu_mask(struct drbd_conf *mdev)
+{
+	int sv, cpu;
+	cpumask_t av_cpu_m;
+
+	if (cpus_weight(mdev->cpu_mask))
+		return mdev->cpu_mask;
+
+	av_cpu_m = cpu_online_map;
+	sv = mdev_to_minor(mdev) % cpus_weight(av_cpu_m);
+
+	for_each_cpu_mask(cpu, av_cpu_m) {
+		if (sv-- == 0)
+			return cpumask_of_cpu(cpu);
+	}
+
+	/* some kernel versions "forget" to add the (cpumask_t) typecast
+	 * to that macro, which results in "parse error before '{'" ;-> */
+	return (cpumask_t) CPU_MASK_ALL; /* Never reached. */
+}
+
+/* modifies the cpu mask of the _current_ thread,
+ * call in the "main loop" of _all_ threads.
+ * no need for any mutex, current won't die prematurely.
+ */
+void drbd_thread_current_set_cpu(struct drbd_conf *mdev)
+{
+	struct task_struct *p = current;
+	struct Drbd_thread *thi =
+		p == mdev->asender.task  ? &mdev->asender  :
+		p == mdev->receiver.task ? &mdev->receiver :
+		p == mdev->worker.task   ? &mdev->worker   :
+		NULL;
+	ERR_IF(thi == NULL)
+		return;
+	if (!thi->reset_cpu_mask)
+		return;
+	thi->reset_cpu_mask = 0;
+	/* preempt_disable();
+	   Thas was a kernel that warned about a call to smp_processor_id() while preemt
+	   was not disabled. It seems that this was fixed in manline. */
+	set_cpus_allowed(p, mdev->cpu_mask);
+	/* preempt_enable(); */
+}
+#endif
+
+/* the appropriate socket mutex must be held already */
+int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,
+			  enum Drbd_Packet_Cmd cmd, struct Drbd_Header *h,
+			  size_t size, unsigned msg_flags)
+{
+	int sent, ok;
+
+	ERR_IF(!h) return FALSE;
+	ERR_IF(!size) return FALSE;
+
+	h->magic   = BE_DRBD_MAGIC;
+	h->command = cpu_to_be16(cmd);
+	h->length  = cpu_to_be16(size-sizeof(struct Drbd_Header));
+
+	dump_packet(mdev, sock, 0, (void *)h, __FILE__, __LINE__);
+	sent = drbd_send(mdev, sock, h, size, msg_flags);
+
+	ok = (sent == size);
+	if (!ok)
+		ERR("short sent %s size=%d sent=%d\n",
+		    cmdname(cmd), (int)size, sent);
+	return ok;
+}
+
+/* don't pass the socket. we may only look at it
+ * when we hold the appropriate socket mutex.
+ */
+int drbd_send_cmd(struct drbd_conf *mdev, int use_data_socket,
+		  enum Drbd_Packet_Cmd cmd, struct Drbd_Header *h, size_t size)
+{
+	int ok = 0;
+	struct socket *sock;
+
+	if (use_data_socket) {
+		mutex_lock(&mdev->data.mutex);
+		sock = mdev->data.socket;
+	} else {
+		mutex_lock(&mdev->meta.mutex);
+		sock = mdev->meta.socket;
+	}
+
+	/* drbd_disconnect() could have called drbd_free_sock()
+	 * while we were waiting in down()... */
+	if (likely(sock != NULL))
+		ok = _drbd_send_cmd(mdev, sock, cmd, h, size, 0);
+
+	if (use_data_socket)
+		mutex_unlock(&mdev->data.mutex);
+	else
+		mutex_unlock(&mdev->meta.mutex);
+	return ok;
+}
+
+int drbd_send_cmd2(struct drbd_conf *mdev, enum Drbd_Packet_Cmd cmd, char *data,
+		   size_t size)
+{
+	struct Drbd_Header h;
+	int ok;
+
+	h.magic   = BE_DRBD_MAGIC;
+	h.command = cpu_to_be16(cmd);
+	h.length  = cpu_to_be16(size);
+
+	if (!drbd_get_data_sock(mdev))
+		return 0;
+
+	dump_packet(mdev, mdev->data.socket, 0, (void *)&h, __FILE__, __LINE__);
+
+	ok = (sizeof(h) ==
+		drbd_send(mdev, mdev->data.socket, &h, sizeof(h), 0));
+	ok = ok && (size ==
+		drbd_send(mdev, mdev->data.socket, data, size, 0));
+
+	drbd_put_data_sock(mdev);
+
+	return ok;
+}
+
+int drbd_send_sync_param(struct drbd_conf *mdev, struct syncer_conf *sc)
+{
+	struct Drbd_SyncParam89_Packet *p;
+	struct socket *sock;
+	int size, rv;
+	const int apv = mdev->agreed_pro_version;
+
+	size = apv <= 87 ? sizeof(struct Drbd_SyncParam_Packet)
+		: apv == 88 ? sizeof(struct Drbd_SyncParam_Packet)
+			+ strlen(mdev->sync_conf.verify_alg) + 1
+		: /* 89 */    sizeof(struct Drbd_SyncParam89_Packet);
+
+	/* used from admin command context and receiver/worker context.
+	 * to avoid kmalloc, grab the socket right here,
+	 * then use the pre-allocated sbuf there */
+	mutex_lock(&mdev->data.mutex);
+	sock = mdev->data.socket;
+
+	if (likely(sock != NULL)) {
+		enum Drbd_Packet_Cmd cmd = apv >= 89 ? SyncParam89 : SyncParam;
+
+		p = &mdev->data.sbuf.SyncParam89;
+
+		/* initialize verify_alg and csums_alg */
+		memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
+
+		p->rate = cpu_to_be32(sc->rate);
+
+		if (apv >= 88)
+			strcpy(p->verify_alg, mdev->sync_conf.verify_alg);
+		if (apv >= 89)
+			strcpy(p->csums_alg, mdev->sync_conf.csums_alg);
+
+		rv = _drbd_send_cmd(mdev, sock, cmd, &p->head, size, 0);
+	} else
+		rv = 0; /* not ok */
+
+	mutex_unlock(&mdev->data.mutex);
+
+	return rv;
+}
+
+int drbd_send_protocol(struct drbd_conf *mdev)
+{
+	struct Drbd_Protocol_Packet *p;
+	int size, rv;
+
+	size = sizeof(struct Drbd_Protocol_Packet);
+
+	if (mdev->agreed_pro_version >= 87)
+		size += strlen(mdev->net_conf->integrity_alg) + 1;
+
+	p = kmalloc(size, GFP_KERNEL);
+	if (p == NULL)
+		return 0;
+
+	p->protocol      = cpu_to_be32(mdev->net_conf->wire_protocol);
+	p->after_sb_0p   = cpu_to_be32(mdev->net_conf->after_sb_0p);
+	p->after_sb_1p   = cpu_to_be32(mdev->net_conf->after_sb_1p);
+	p->after_sb_2p   = cpu_to_be32(mdev->net_conf->after_sb_2p);
+	p->want_lose     = cpu_to_be32(mdev->net_conf->want_lose);
+	p->two_primaries = cpu_to_be32(mdev->net_conf->two_primaries);
+
+	if (mdev->agreed_pro_version >= 87)
+		strcpy(p->integrity_alg, mdev->net_conf->integrity_alg);
+
+	rv = drbd_send_cmd(mdev, USE_DATA_SOCKET, ReportProtocol,
+			   (struct Drbd_Header *)p, size);
+	kfree(p);
+	return rv;
+}
+
+int drbd_send_uuids(struct drbd_conf *mdev)
+{
+	struct Drbd_GenCnt_Packet p;
+	int i;
+
+	u64 uuid_flags = 0;
+
+	if (!inc_local_if_state(mdev, Negotiating))
+		return 1;
+
+	for (i = Current; i < UUID_SIZE; i++)
+		p.uuid[i] = mdev->bc ? cpu_to_be64(mdev->bc->md.uuid[i]) : 0;
+
+	mdev->comm_bm_set = drbd_bm_total_weight(mdev);
+	p.uuid[UUID_SIZE] = cpu_to_be64(mdev->comm_bm_set);
+	uuid_flags |= mdev->net_conf->want_lose ? 1 : 0;
+	uuid_flags |= test_bit(CRASHED_PRIMARY, &mdev->flags) ? 2 : 0;
+	uuid_flags |= mdev->new_state_tmp.disk == Inconsistent ? 4 : 0;
+	p.uuid[UUID_FLAGS] = cpu_to_be64(uuid_flags);
+
+	dec_local(mdev);
+
+	return drbd_send_cmd(mdev, USE_DATA_SOCKET, ReportUUIDs,
+			     (struct Drbd_Header *)&p, sizeof(p));
+}
+
+int drbd_send_sync_uuid(struct drbd_conf *mdev, u64 val)
+{
+	struct Drbd_SyncUUID_Packet p;
+
+	p.uuid = cpu_to_be64(val);
+
+	return drbd_send_cmd(mdev, USE_DATA_SOCKET, ReportSyncUUID,
+			     (struct Drbd_Header *)&p, sizeof(p));
+}
+
+int drbd_send_sizes(struct drbd_conf *mdev)
+{
+	struct Drbd_Sizes_Packet p;
+	sector_t d_size, u_size;
+	int q_order_type;
+	int ok;
+
+	if (inc_local_if_state(mdev, Negotiating)) {
+		D_ASSERT(mdev->bc->backing_bdev);
+		d_size = drbd_get_max_capacity(mdev->bc);
+		u_size = mdev->bc->dc.disk_size;
+		q_order_type = drbd_queue_order_type(mdev);
+		p.queue_order_type = cpu_to_be32(drbd_queue_order_type(mdev));
+		dec_local(mdev);
+	} else {
+		d_size = 0;
+		u_size = 0;
+		q_order_type = QUEUE_ORDERED_NONE;
+	}
+
+	p.d_size = cpu_to_be64(d_size);
+	p.u_size = cpu_to_be64(u_size);
+	p.c_size = cpu_to_be64(drbd_get_capacity(mdev->this_bdev));
+	p.max_segment_size = cpu_to_be32(mdev->rq_queue->max_segment_size);
+	p.queue_order_type = cpu_to_be32(q_order_type);
+
+	ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, ReportSizes,
+			   (struct Drbd_Header *)&p, sizeof(p));
+	return ok;
+}
+
+/**
+ * drbd_send_state:
+ * Informs the peer about our state. Only call it when
+ * mdev->state.conn >= Connected (I.e. you may not call it while in
+ * WFReportParams. Though there is one valid and necessary exception,
+ * drbd_connect() calls drbd_send_state() while in it WFReportParams.
+ */
+int drbd_send_state(struct drbd_conf *mdev)
+{
+	struct socket *sock;
+	struct Drbd_State_Packet p;
+	int ok = 0;
+
+	/* Grab state lock so we wont send state if we're in the middle
+	 * of a cluster wide state change on another thread */
+	drbd_state_lock(mdev);
+
+	mutex_lock(&mdev->data.mutex);
+
+	p.state = cpu_to_be32(mdev->state.i); /* Within the send mutex */
+	sock = mdev->data.socket;
+
+	if (likely(sock != NULL)) {
+		ok = _drbd_send_cmd(mdev, sock, ReportState,
+				    (struct Drbd_Header *)&p, sizeof(p), 0);
+	}
+
+	mutex_unlock(&mdev->data.mutex);
+
+	drbd_state_unlock(mdev);
+	return ok;
+}
+
+int drbd_send_state_req(struct drbd_conf *mdev,
+	union drbd_state_t mask, union drbd_state_t val)
+{
+	struct Drbd_Req_State_Packet p;
+
+	p.mask    = cpu_to_be32(mask.i);
+	p.val     = cpu_to_be32(val.i);
+
+	return drbd_send_cmd(mdev, USE_DATA_SOCKET, StateChgRequest,
+			     (struct Drbd_Header *)&p, sizeof(p));
+}
+
+int drbd_send_sr_reply(struct drbd_conf *mdev, int retcode)
+{
+	struct Drbd_RqS_Reply_Packet p;
+
+	p.retcode    = cpu_to_be32(retcode);
+
+	return drbd_send_cmd(mdev, USE_META_SOCKET, StateChgReply,
+			     (struct Drbd_Header *)&p, sizeof(p));
+}
+
+
+/* See the comment at receive_bitmap() */
+int _drbd_send_bitmap(struct drbd_conf *mdev)
+{
+	int want;
+	int ok = TRUE;
+	int bm_i = 0;
+	size_t bm_words, num_words;
+	unsigned long *buffer;
+	struct Drbd_Header *p;
+
+	ERR_IF(!mdev->bitmap) return FALSE;
+
+	/* maybe we should use some per thread scratch page,
+	 * and allocate that during initial device creation? */
+	p = (struct Drbd_Header *) __get_free_page(GFP_NOIO);
+	if (!p) {
+		ERR("failed to allocate one page buffer in %s\n", __func__);
+		return FALSE;
+	}
+	bm_words = drbd_bm_words(mdev);
+	buffer = (unsigned long *)p->payload;
+
+	if (inc_local(mdev)) {
+		if (drbd_md_test_flag(mdev->bc, MDF_FullSync)) {
+			INFO("Writing the whole bitmap, MDF_FullSync was set.\n");
+			drbd_bm_set_all(mdev);
+			if (drbd_bm_write(mdev)) {
+				/* write_bm did fail! Leave full sync flag set in Meta Data
+				 * but otherwise process as per normal - need to tell other
+				 * side that a full resync is required! */
+				ERR("Failed to write bitmap to disk!\n");
+			} else {
+				drbd_md_clear_flag(mdev, MDF_FullSync);
+				drbd_md_sync(mdev);
+			}
+		}
+		dec_local(mdev);
+	}
+
+	/*
+	 * maybe TODO use some simple compression scheme, nowadays there are
+	 * some such algorithms in the kernel anyways.
+	 */
+	do {
+		num_words = min_t(size_t, BM_PACKET_WORDS, bm_words - bm_i);
+		want = num_words * sizeof(long);
+		if (want)
+			drbd_bm_get_lel(mdev, bm_i, num_words, buffer);
+		ok = _drbd_send_cmd(mdev, mdev->data.socket, ReportBitMap,
+				   p, sizeof(*p) + want, 0);
+		bm_i += num_words;
+	} while (ok && want);
+
+	free_page((unsigned long) p);
+	return ok;
+}
+
+int drbd_send_bitmap(struct drbd_conf *mdev)
+{
+	int err;
+
+	if (!drbd_get_data_sock(mdev))
+		return -1;
+	err = !_drbd_send_bitmap(mdev);
+	drbd_put_data_sock(mdev);
+	return err;
+}
+
+int drbd_send_b_ack(struct drbd_conf *mdev, u32 barrier_nr, u32 set_size)
+{
+	int ok;
+	struct Drbd_BarrierAck_Packet p;
+
+	p.barrier  = barrier_nr;
+	p.set_size = cpu_to_be32(set_size);
+
+	if (mdev->state.conn < Connected)
+		return FALSE;
+	ok = drbd_send_cmd(mdev, USE_META_SOCKET, BarrierAck,
+			(struct Drbd_Header *)&p, sizeof(p));
+	return ok;
+}
+
+/**
+ * _drbd_send_ack:
+ * This helper function expects the sector and block_id parameter already
+ * in big endian!
+ */
+STATIC int _drbd_send_ack(struct drbd_conf *mdev, enum Drbd_Packet_Cmd cmd,
+			  u64 sector,
+			  u32 blksize,
+			  u64 block_id)
+{
+	int ok;
+	struct Drbd_BlockAck_Packet p;
+
+	p.sector   = sector;
+	p.block_id = block_id;
+	p.blksize  = blksize;
+	p.seq_num  = cpu_to_be32(atomic_add_return(1, &mdev->packet_seq));
+
+	if (!mdev->meta.socket || mdev->state.conn < Connected)
+		return FALSE;
+	ok = drbd_send_cmd(mdev, USE_META_SOCKET, cmd,
+				(struct Drbd_Header *)&p, sizeof(p));
+	return ok;
+}
+
+int drbd_send_ack_dp(struct drbd_conf *mdev, enum Drbd_Packet_Cmd cmd,
+		     struct Drbd_Data_Packet *dp)
+{
+	const int header_size = sizeof(struct Drbd_Data_Packet)
+			      - sizeof(struct Drbd_Header);
+	int data_size  = ((struct Drbd_Header *)dp)->length - header_size;
+
+	return _drbd_send_ack(mdev, cmd, dp->sector, cpu_to_be32(data_size),
+			      dp->block_id);
+}
+
+int drbd_send_ack_rp(struct drbd_conf *mdev, enum Drbd_Packet_Cmd cmd,
+		     struct Drbd_BlockRequest_Packet *rp)
+{
+	return _drbd_send_ack(mdev, cmd, rp->sector, rp->blksize, rp->block_id);
+}
+
+int drbd_send_ack(struct drbd_conf *mdev,
+	enum Drbd_Packet_Cmd cmd, struct Tl_epoch_entry *e)
+{
+	return _drbd_send_ack(mdev, cmd,
+			      cpu_to_be64(e->sector),
+			      cpu_to_be32(e->size),
+			      e->block_id);
+}
+
+/* This function misuses the block_id field to signal if the blocks
+ * are is sync or not. */
+int drbd_send_ack_ex(struct drbd_conf *mdev, enum Drbd_Packet_Cmd cmd,
+		     sector_t sector, int blksize, u64 block_id)
+{
+	return _drbd_send_ack(mdev, cmd,
+			      cpu_to_be64(sector),
+			      cpu_to_be32(blksize),
+			      cpu_to_be64(block_id));
+}
+
+int drbd_send_drequest(struct drbd_conf *mdev, int cmd,
+		       sector_t sector, int size, u64 block_id)
+{
+	int ok;
+	struct Drbd_BlockRequest_Packet p;
+
+	p.sector   = cpu_to_be64(sector);
+	p.block_id = block_id;
+	p.blksize  = cpu_to_be32(size);
+
+	ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, cmd,
+				(struct Drbd_Header *)&p, sizeof(p));
+	return ok;
+}
+
+int drbd_send_drequest_csum(struct drbd_conf *mdev,
+			    sector_t sector, int size,
+			    void *digest, int digest_size,
+			    enum Drbd_Packet_Cmd cmd)
+{
+	int ok;
+	struct Drbd_BlockRequest_Packet p;
+
+	p.sector   = cpu_to_be64(sector);
+	p.block_id = BE_DRBD_MAGIC + 0xbeef;
+	p.blksize  = cpu_to_be32(size);
+
+	p.head.magic   = BE_DRBD_MAGIC;
+	p.head.command = cpu_to_be16(cmd);
+	p.head.length  = cpu_to_be16(sizeof(p) - sizeof(struct Drbd_Header) + digest_size);
+
+	mutex_lock(&mdev->data.mutex);
+
+	ok = (sizeof(p) == drbd_send(mdev, mdev->data.socket, &p, sizeof(p), 0));
+	ok = ok && (digest_size == drbd_send(mdev, mdev->data.socket, digest, digest_size, 0));
+
+	mutex_unlock(&mdev->data.mutex);
+
+	return ok;
+}
+
+int drbd_send_ov_request(struct drbd_conf *mdev, sector_t sector, int size)
+{
+	int ok;
+	struct Drbd_BlockRequest_Packet p;
+
+	p.sector   = cpu_to_be64(sector);
+	p.block_id = BE_DRBD_MAGIC + 0xbabe;
+	p.blksize  = cpu_to_be32(size);
+
+	ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, OVRequest,
+			   (struct Drbd_Header *)&p, sizeof(p));
+	return ok;
+}
+
+/* called on sndtimeo
+ * returns FALSE if we should retry,
+ * TRUE if we think connection is dead
+ */
+STATIC int we_should_drop_the_connection(struct drbd_conf *mdev, struct socket *sock)
+{
+	int drop_it;
+	/* long elapsed = (long)(jiffies - mdev->last_received); */
+
+	drop_it =   mdev->meta.socket == sock
+		|| !mdev->asender.task
+		|| get_t_state(&mdev->asender) != Running
+		|| mdev->state.conn < Connected;
+
+	if (drop_it)
+		return TRUE;
+
+	drop_it = !--mdev->ko_count;
+	if (!drop_it) {
+		ERR("[%s/%d] sock_sendmsg time expired, ko = %u\n",
+		       current->comm, current->pid, mdev->ko_count);
+		request_ping(mdev);
+	}
+
+	return drop_it; /* && (mdev->state == Primary) */;
+}
+
+/* The idea of sendpage seems to be to put some kind of reference
+ * to the page into the skb, and to hand it over to the NIC. In
+ * this process get_page() gets called.
+ *
+ * As soon as the page was really sent over the network put_page()
+ * gets called by some part of the network layer. [ NIC driver? ]
+ *
+ * [ get_page() / put_page() increment/decrement the count. If count
+ *   reaches 0 the page will be freed. ]
+ *
+ * This works nicely with pages from FSs.
+ * But this means that in protocol A we might signal IO completion too early!
+ *
+ * In order not to corrupt data during a resync we must make sure
+ * that we do not reuse our own buffer pages (EEs) to early, therefore
+ * we have the net_ee list.
+ *
+ * XFS seems to have problems, still, it submits pages with page_count == 0!
+ * As a workaround, we disable sendpage on pages
+ * with page_count == 0 or PageSlab.
+ */
+STATIC int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page,
+		   int offset, size_t size)
+{
+       int ret;
+       ret = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, 0);
+       kunmap(page);
+       return ret;
+}
+
+int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
+		    int offset, size_t size)
+{
+	mm_segment_t oldfs = get_fs();
+	int sent, ok;
+	int len = size;
+
+#ifdef SHOW_SENDPAGE_USAGE
+	unsigned long now = jiffies;
+	static unsigned long total;
+	static unsigned long fallback;
+	static unsigned long last_rep;
+
+	/* report statistics every hour,
+	 * if we had at least one fallback.
+	 */
+	++total;
+	if (fallback && time_before(last_rep+3600*HZ, now)) {
+		last_rep = now;
+		printk(KERN_INFO "drbd: sendpage() omitted: %lu/%lu\n",
+			fallback, total);
+	}
+#endif
+
+	/* PARANOIA. if this ever triggers,
+	 * something in the layers above us is really kaputt.
+	 *one roundtrip later:
+	 * doh. it triggered. so XFS _IS_ really kaputt ...
+	 * oh well...
+	 */
+	if ((page_count(page) < 1) || PageSlab(page)) {
+		/* e.g. XFS meta- & log-data is in slab pages, which have a
+		 * page_count of 0 and/or have PageSlab() set...
+		 */
+#ifdef SHOW_SENDPAGE_USAGE
+		++fallback;
+#endif
+		sent = _drbd_no_send_page(mdev, page, offset, size);
+		if (likely(sent > 0))
+			len -= sent;
+		goto out;
+	}
+
+	set_fs(KERNEL_DS);
+	do {
+		sent = mdev->data.socket->ops->sendpage(mdev->data.socket, page,
+							offset, len,
+							MSG_NOSIGNAL);
+		if (sent == -EAGAIN) {
+			if (we_should_drop_the_connection(mdev,
+							  mdev->data.socket))
+				break;
+			else
+				continue;
+		}
+		if (sent <= 0) {
+			drbd_WARN("%s: size=%d len=%d sent=%d\n",
+			     __func__, (int)size, len, sent);
+			break;
+		}
+		len    -= sent;
+		offset += sent;
+	} while (len > 0 /* THINK && mdev->cstate >= Connected*/);
+	set_fs(oldfs);
+
+out:
+	ok = (len == 0);
+	if (likely(ok))
+		mdev->send_cnt += size>>9;
+	return ok;
+}
+
+static inline int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio)
+{
+	struct bio_vec *bvec;
+	int i;
+	__bio_for_each_segment(bvec, bio, i, 0) {
+		if (!_drbd_no_send_page(mdev, bvec->bv_page,
+				     bvec->bv_offset, bvec->bv_len))
+			return 0;
+	}
+	return 1;
+}
+
+static inline int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
+{
+	struct bio_vec *bvec;
+	int i;
+	__bio_for_each_segment(bvec, bio, i, 0) {
+		if (!_drbd_send_page(mdev, bvec->bv_page,
+				     bvec->bv_offset, bvec->bv_len))
+			return 0;
+	}
+
+	return 1;
+}
+
+/* Used to send write requests
+ * Primary -> Peer	(Data)
+ */
+int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
+{
+	int ok = 1;
+	struct Drbd_Data_Packet p;
+	unsigned int dp_flags = 0;
+	void *dgb;
+	int dgs;
+
+	if (!drbd_get_data_sock(mdev))
+		return 0;
+
+	dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
+		crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;
+
+	p.head.magic   = BE_DRBD_MAGIC;
+	p.head.command = cpu_to_be16(Data);
+	p.head.length  =
+		cpu_to_be16(sizeof(p) - sizeof(struct Drbd_Header) + dgs + req->size);
+
+	p.sector   = cpu_to_be64(req->sector);
+	p.block_id = (unsigned long)req;
+	p.seq_num  = cpu_to_be32(req->seq_num =
+				 atomic_add_return(1, &mdev->packet_seq));
+	dp_flags = 0;
+
+	/* NOTE: no need to check if barriers supported here as we would
+	 *       not pass the test in make_request_common in that case
+	 */
+	if (bio_barrier(req->master_bio))
+		dp_flags |= DP_HARDBARRIER;
+	if (bio_sync(req->master_bio))
+		dp_flags |= DP_RW_SYNC;
+	if (mdev->state.conn >= SyncSource &&
+	    mdev->state.conn <= PausedSyncT)
+		dp_flags |= DP_MAY_SET_IN_SYNC;
+
+	p.dp_flags = cpu_to_be32(dp_flags);
+	dump_packet(mdev, mdev->data.socket, 0, (void *)&p, __FILE__, __LINE__);
+	set_bit(UNPLUG_REMOTE, &mdev->flags);
+	ok = (sizeof(p) ==
+		drbd_send(mdev, mdev->data.socket, &p, sizeof(p), MSG_MORE));
+	if (ok && dgs) {
+		dgb = mdev->int_dig_out;
+		drbd_csum(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);
+		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);
+	}
+	if (ok) {
+		if (mdev->net_conf->wire_protocol == DRBD_PROT_A)
+			ok = _drbd_send_bio(mdev, req->master_bio);
+		else
+			ok = _drbd_send_zc_bio(mdev, req->master_bio);
+	}
+
+	drbd_put_data_sock(mdev);
+	return ok;
+}
+
+/* answer packet, used to send data back for read requests:
+ *  Peer       -> (diskless) Primary   (DataReply)
+ *  SyncSource -> SyncTarget         (RSDataReply)
+ */
+int drbd_send_block(struct drbd_conf *mdev, enum Drbd_Packet_Cmd cmd,
+		    struct Tl_epoch_entry *e)
+{
+	int ok;
+	struct Drbd_Data_Packet p;
+	void *dgb;
+	int dgs;
+
+	dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
+		crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;
+
+	p.head.magic   = BE_DRBD_MAGIC;
+	p.head.command = cpu_to_be16(cmd);
+	p.head.length  =
+		cpu_to_be16(sizeof(p) - sizeof(struct Drbd_Header) + dgs + e->size);
+
+	p.sector   = cpu_to_be64(e->sector);
+	p.block_id = e->block_id;
+	/* p.seq_num  = 0;    No sequence numbers here.. */
+
+	/* Only called by our kernel thread.
+	 * This one may be interupted by DRBD_SIG and/or DRBD_SIGKILL
+	 * in response to admin command or module unload.
+	 */
+	if (!drbd_get_data_sock(mdev))
+		return 0;
+
+	dump_packet(mdev, mdev->data.socket, 0, (void *)&p, __FILE__, __LINE__);
+	ok = sizeof(p) == drbd_send(mdev, mdev->data.socket, &p,
+					sizeof(p), MSG_MORE);
+	if (ok && dgs) {
+		dgb = mdev->int_dig_out;
+		drbd_csum(mdev, mdev->integrity_w_tfm, e->private_bio, dgb);
+		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);
+	}
+	if (ok)
+		ok = _drbd_send_zc_bio(mdev, e->private_bio);
+
+	drbd_put_data_sock(mdev);
+	return ok;
+}
+
+/*
+  drbd_send distinguishes two cases:
+
+  Packets sent via the data socket "sock"
+  and packets sent via the meta data socket "msock"
+
+		    sock                      msock
+  -----------------+-------------------------+------------------------------
+  timeout           conf.timeout / 2          conf.timeout / 2
+  timeout action    send a ping via msock     Abort communication
+					      and close all sockets
+*/
+
+/*
+ * you must have down()ed the appropriate [m]sock_mutex elsewhere!
+ */
+int drbd_send(struct drbd_conf *mdev, struct socket *sock,
+	      void *buf, size_t size, unsigned msg_flags)
+{
+	struct kvec iov;
+	struct msghdr msg;
+	int rv, sent = 0;
+
+	if (!sock)
+		return -1000;
+
+	/* THINK  if (signal_pending) return ... ? */
+
+	iov.iov_base = buf;
+	iov.iov_len  = size;
+
+	msg.msg_name       = NULL;
+	msg.msg_namelen    = 0;
+	msg.msg_control    = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags      = msg_flags | MSG_NOSIGNAL;
+
+	if (sock == mdev->data.socket)
+		mdev->ko_count = mdev->net_conf->ko_count;
+	do {
+		/* STRANGE
+		 * tcp_sendmsg does _not_ use its size parameter at all ?
+		 *
+		 * -EAGAIN on timeout, -EINTR on signal.
+		 */
+/* THINK
+ * do we need to block DRBD_SIG if sock == &meta.socket ??
+ * otherwise wake_asender() might interrupt some send_*Ack !
+ */
+		rv = kernel_sendmsg(sock, &msg, &iov, 1, size);
+		if (rv == -EAGAIN) {
+			if (we_should_drop_the_connection(mdev, sock))
+				break;
+			else
+				continue;
+		}
+		D_ASSERT(rv != 0);
+		if (rv == -EINTR) {
+			flush_signals(current);
+			rv = 0;
+		}
+		if (rv < 0)
+			break;
+		sent += rv;
+		iov.iov_base += rv;
+		iov.iov_len  -= rv;
+	} while (sent < size);
+
+	if (rv <= 0) {
+		if (rv != -EAGAIN) {
+			ERR("%s_sendmsg returned %d\n",
+			    sock == mdev->meta.socket ? "msock" : "sock",
+			    rv);
+			drbd_force_state(mdev, NS(conn, BrokenPipe));
+		} else
+			drbd_force_state(mdev, NS(conn, Timeout));
+	}
+
+	return sent;
+}
+
+static int drbd_open(struct block_device *bdev, fmode_t mode)
+{
+	struct drbd_conf *mdev = bdev->bd_disk->private_data;
+	unsigned long flags;
+	int rv = 0;
+
+	spin_lock_irqsave(&mdev->req_lock, flags);
+	/* to have a stable mdev->state.role
+	 * and no race with updating open_cnt */
+
+	if (mdev->state.role != Primary) {
+		if (mode & FMODE_WRITE)
+			rv = -EROFS;
+		else if (!allow_oos)
+			rv = -EMEDIUMTYPE;
+	}
+
+	if (!rv)
+		mdev->open_cnt++;
+	spin_unlock_irqrestore(&mdev->req_lock, flags);
+
+	return rv;
+}
+
+static int drbd_release(struct gendisk *gd, fmode_t mode)
+{
+	struct drbd_conf *mdev = gd->private_data;
+	mdev->open_cnt--;
+	return 0;
+}
+
+STATIC void drbd_unplug_fn(struct request_queue *q)
+{
+	struct drbd_conf *mdev = q->queuedata;
+
+	MTRACE(TraceTypeUnplug, TraceLvlSummary,
+	       INFO("got unplugged ap_bio_count=%d\n",
+		    atomic_read(&mdev->ap_bio_cnt));
+	       );
+
+	/* unplug FIRST */
+	spin_lock_irq(q->queue_lock);
+	blk_remove_plug(q);
+	spin_unlock_irq(q->queue_lock);
+
+	/* only if connected */
+	spin_lock_irq(&mdev->req_lock);
+	if (mdev->state.pdsk >= Inconsistent && mdev->state.conn >= Connected) {
+		D_ASSERT(mdev->state.role == Primary);
+		if (test_and_clear_bit(UNPLUG_REMOTE, &mdev->flags)) {
+			/* add to the data.work queue,
+			 * unless already queued.
+			 * XXX this might be a good addition to drbd_queue_work
+			 * anyways, to detect "double queuing" ... */
+			if (list_empty(&mdev->unplug_work.list))
+				drbd_queue_work(&mdev->data.work,
+						&mdev->unplug_work);
+		}
+	}
+	spin_unlock_irq(&mdev->req_lock);
+
+	if (mdev->state.disk >= Inconsistent)
+		drbd_kick_lo(mdev);
+}
+
+STATIC void drbd_set_defaults(struct drbd_conf *mdev)
+{
+	mdev->sync_conf.after      = DRBD_AFTER_DEF;
+	mdev->sync_conf.rate       = DRBD_RATE_DEF;
+	mdev->sync_conf.al_extents = DRBD_AL_EXTENTS_DEF;
+	mdev->state = (union drbd_state_t) {
+		{ .role = Secondary,
+		  .peer = Unknown,
+		  .conn = StandAlone,
+		  .disk = Diskless,
+		  .pdsk = DUnknown,
+		  .susp = 0
+		} };
+}
+
+void drbd_init_set_defaults(struct drbd_conf *mdev)
+{
+	/* the memset(,0,) did most of this.
+	 * note: only assignments, no allocation in here */
+
+	drbd_set_defaults(mdev);
+
+	/* for now, we do NOT yet support it,
+	 * even though we start some framework
+	 * to eventually support barriers */
+	set_bit(NO_BARRIER_SUPP, &mdev->flags);
+
+	atomic_set(&mdev->ap_bio_cnt, 0);
+	atomic_set(&mdev->ap_pending_cnt, 0);
+	atomic_set(&mdev->rs_pending_cnt, 0);
+	atomic_set(&mdev->unacked_cnt, 0);
+	atomic_set(&mdev->local_cnt, 0);
+	atomic_set(&mdev->net_cnt, 0);
+	atomic_set(&mdev->packet_seq, 0);
+	atomic_set(&mdev->pp_in_use, 0);
+
+	mutex_init(&mdev->md_io_mutex);
+	mutex_init(&mdev->data.mutex);
+	mutex_init(&mdev->meta.mutex);
+	sema_init(&mdev->data.work.s, 0);
+	sema_init(&mdev->meta.work.s, 0);
+	mutex_init(&mdev->state_mutex);
+
+	spin_lock_init(&mdev->data.work.q_lock);
+	spin_lock_init(&mdev->meta.work.q_lock);
+
+	spin_lock_init(&mdev->al_lock);
+	spin_lock_init(&mdev->req_lock);
+	spin_lock_init(&mdev->peer_seq_lock);
+	spin_lock_init(&mdev->epoch_lock);
+
+	INIT_LIST_HEAD(&mdev->active_ee);
+	INIT_LIST_HEAD(&mdev->sync_ee);
+	INIT_LIST_HEAD(&mdev->done_ee);
+	INIT_LIST_HEAD(&mdev->read_ee);
+	INIT_LIST_HEAD(&mdev->net_ee);
+	INIT_LIST_HEAD(&mdev->resync_reads);
+	INIT_LIST_HEAD(&mdev->data.work.q);
+	INIT_LIST_HEAD(&mdev->meta.work.q);
+	INIT_LIST_HEAD(&mdev->resync_work.list);
+	INIT_LIST_HEAD(&mdev->unplug_work.list);
+	INIT_LIST_HEAD(&mdev->md_sync_work.list);
+	INIT_LIST_HEAD(&mdev->bm_io_work.w.list);
+	mdev->resync_work.cb  = w_resync_inactive;
+	mdev->unplug_work.cb  = w_send_write_hint;
+	mdev->md_sync_work.cb = w_md_sync;
+	mdev->bm_io_work.w.cb = w_bitmap_io;
+	init_timer(&mdev->resync_timer);
+	init_timer(&mdev->md_sync_timer);
+	mdev->resync_timer.function = resync_timer_fn;
+	mdev->resync_timer.data = (unsigned long) mdev;
+	mdev->md_sync_timer.function = md_sync_timer_fn;
+	mdev->md_sync_timer.data = (unsigned long) mdev;
+
+	init_waitqueue_head(&mdev->misc_wait);
+	init_waitqueue_head(&mdev->state_wait);
+	init_waitqueue_head(&mdev->ee_wait);
+	init_waitqueue_head(&mdev->al_wait);
+	init_waitqueue_head(&mdev->seq_wait);
+
+	drbd_thread_init(mdev, &mdev->receiver, drbdd_init);
+	drbd_thread_init(mdev, &mdev->worker, drbd_worker);
+	drbd_thread_init(mdev, &mdev->asender, drbd_asender);
+
+	mdev->agreed_pro_version = PRO_VERSION_MAX;
+	mdev->write_ordering = WO_bio_barrier;
+#ifdef __arch_um__
+	INFO("mdev = 0x%p\n", mdev);
+#endif
+	mdev->resync_wenr = LC_FREE;
+}
+
+void drbd_mdev_cleanup(struct drbd_conf *mdev)
+{
+	if (mdev->receiver.t_state != None)
+		ERR("ASSERT FAILED: receiver t_state == %d expected 0.\n",
+				mdev->receiver.t_state);
+
+	/* no need to lock it, I'm the only thread alive */
+	if (atomic_read(&mdev->current_epoch->epoch_size) !=  0)
+		ERR("epoch_size:%d\n", atomic_read(&mdev->current_epoch->epoch_size));
+	mdev->al_writ_cnt  =
+	mdev->bm_writ_cnt  =
+	mdev->read_cnt     =
+	mdev->recv_cnt     =
+	mdev->send_cnt     =
+	mdev->writ_cnt     =
+	mdev->p_size       =
+	mdev->rs_start     =
+	mdev->rs_total     =
+	mdev->rs_failed    =
+	mdev->rs_mark_left =
+	mdev->rs_mark_time = 0;
+	D_ASSERT(mdev->net_conf == NULL);
+
+	drbd_set_my_capacity(mdev, 0);
+	drbd_bm_resize(mdev, 0);
+	drbd_bm_cleanup(mdev);
+
+	drbd_free_resources(mdev);
+
+	/*
+	 * currently we drbd_init_ee only on module load, so
+	 * we may do drbd_release_ee only on module unload!
+	 */
+	D_ASSERT(list_empty(&mdev->active_ee));
+	D_ASSERT(list_empty(&mdev->sync_ee));
+	D_ASSERT(list_empty(&mdev->done_ee));
+	D_ASSERT(list_empty(&mdev->read_ee));
+	D_ASSERT(list_empty(&mdev->net_ee));
+	D_ASSERT(list_empty(&mdev->resync_reads));
+	D_ASSERT(list_empty(&mdev->data.work.q));
+	D_ASSERT(list_empty(&mdev->meta.work.q));
+	D_ASSERT(list_empty(&mdev->resync_work.list));
+	D_ASSERT(list_empty(&mdev->unplug_work.list));
+
+}
+
+
+STATIC void drbd_destroy_mempools(void)
+{
+	struct page *page;
+
+	while (drbd_pp_pool) {
+		page = drbd_pp_pool;
+		drbd_pp_pool = (struct page *)page_private(page);
+		__free_page(page);
+		drbd_pp_vacant--;
+	}
+
+	/* D_ASSERT(atomic_read(&drbd_pp_vacant)==0); */
+
+	if (drbd_ee_mempool)
+		mempool_destroy(drbd_ee_mempool);
+	if (drbd_request_mempool)
+		mempool_destroy(drbd_request_mempool);
+	if (drbd_ee_cache)
+		kmem_cache_destroy(drbd_ee_cache);
+	if (drbd_request_cache)
+		kmem_cache_destroy(drbd_request_cache);
+
+	drbd_ee_mempool      = NULL;
+	drbd_request_mempool = NULL;
+	drbd_ee_cache        = NULL;
+	drbd_request_cache   = NULL;
+
+	return;
+}
+
+STATIC int drbd_create_mempools(void)
+{
+	struct page *page;
+	const int number = (DRBD_MAX_SEGMENT_SIZE/PAGE_SIZE) * minor_count;
+	int i;
+
+	/* prepare our caches and mempools */
+	drbd_request_mempool = NULL;
+	drbd_ee_cache        = NULL;
+	drbd_request_cache   = NULL;
+	drbd_pp_pool         = NULL;
+
+	/* caches */
+	drbd_request_cache = kmem_cache_create(
+		"drbd_req_cache", sizeof(struct drbd_request), 0, 0, NULL);
+	if (drbd_request_cache == NULL)
+		goto Enomem;
+
+	drbd_ee_cache = kmem_cache_create(
+		"drbd_ee_cache", sizeof(struct Tl_epoch_entry), 0, 0, NULL);
+	if (drbd_ee_cache == NULL)
+		goto Enomem;
+
+	/* mempools */
+	drbd_request_mempool = mempool_create(number,
+		mempool_alloc_slab, mempool_free_slab, drbd_request_cache);
+	if (drbd_request_mempool == NULL)
+		goto Enomem;
+
+	drbd_ee_mempool = mempool_create(number,
+		mempool_alloc_slab, mempool_free_slab, drbd_ee_cache);
+	if (drbd_request_mempool == NULL)
+		goto Enomem;
+
+	/* drbd's page pool */
+	spin_lock_init(&drbd_pp_lock);
+
+	for (i = 0; i < number; i++) {
+		page = alloc_page(GFP_HIGHUSER);
+		if (!page)
+			goto Enomem;
+		set_page_private(page, (unsigned long)drbd_pp_pool);
+		drbd_pp_pool = page;
+	}
+	drbd_pp_vacant = number;
+
+	return 0;
+
+Enomem:
+	drbd_destroy_mempools(); /* in case we allocated some */
+	return -ENOMEM;
+}
+
+STATIC int drbd_notify_sys(struct notifier_block *this, unsigned long code,
+	void *unused)
+{
+	/* just so we have it.  you never know what interessting things we
+	 * might want to do here some day...
+	 */
+
+	return NOTIFY_DONE;
+}
+
+STATIC struct notifier_block drbd_notifier = {
+	.notifier_call = drbd_notify_sys,
+};
+
+static void drbd_release_ee_lists(struct drbd_conf *mdev)
+{
+	int rr;
+
+	rr = drbd_release_ee(mdev, &mdev->active_ee);
+	if (rr)
+		ERR("%d EEs in active list found!\n", rr);
+
+	rr = drbd_release_ee(mdev, &mdev->sync_ee);
+	if (rr)
+		ERR("%d EEs in sync list found!\n", rr);
+
+	rr = drbd_release_ee(mdev, &mdev->read_ee);
+	if (rr)
+		ERR("%d EEs in read list found!\n", rr);
+
+	rr = drbd_release_ee(mdev, &mdev->done_ee);
+	if (rr)
+		ERR("%d EEs in done list found!\n", rr);
+
+	rr = drbd_release_ee(mdev, &mdev->net_ee);
+	if (rr)
+		ERR("%d EEs in net list found!\n", rr);
+}
+
+/* caution. no locking.
+ * currently only used from module cleanup code. */
+static void drbd_delete_device(unsigned int minor)
+{
+	struct drbd_conf *mdev = minor_to_mdev(minor);
+
+	if (!mdev)
+		return;
+
+	/* paranoia asserts */
+	if (mdev->open_cnt != 0)
+		ERR("open_cnt = %d in %s:%u", mdev->open_cnt,
+				__FILE__ , __LINE__);
+
+	ERR_IF (!list_empty(&mdev->data.work.q)) {
+		struct list_head *lp;
+		list_for_each(lp, &mdev->data.work.q) {
+			DUMPP(lp);
+		}
+	};
+	/* end paranoia asserts */
+
+	del_gendisk(mdev->vdisk);
+
+	/* cleanup stuff that may have been allocated during
+	 * device (re-)configuration or state changes */
+
+	if (mdev->this_bdev)
+		bdput(mdev->this_bdev);
+
+	drbd_free_resources(mdev);
+
+	drbd_release_ee_lists(mdev);
+
+	/* should be free'd on disconnect? */
+	kfree(mdev->ee_hash);
+	/*
+	mdev->ee_hash_s = 0;
+	mdev->ee_hash = NULL;
+	*/
+
+	/* should be free'd on detach? */
+	if (mdev->md_io_tmpp)
+		__free_page(mdev->md_io_tmpp);
+
+	if (mdev->act_log)
+		lc_free(mdev->act_log);
+	if (mdev->resync)
+		lc_free(mdev->resync);
+
+	kfree(mdev->p_uuid);
+	/* mdev->p_uuid = NULL; */
+
+	kfree(mdev->int_dig_out);
+	kfree(mdev->int_dig_in);
+	kfree(mdev->int_dig_vv);
+
+	/* cleanup the rest that has been
+	 * allocated from drbd_new_device
+	 * and actually free the mdev itself */
+	drbd_free_mdev(mdev);
+}
+
+STATIC void drbd_cleanup(void)
+{
+	unsigned int i;
+
+	unregister_reboot_notifier(&drbd_notifier);
+
+	drbd_nl_cleanup();
+
+	if (minor_table) {
+		if (drbd_proc)
+			remove_proc_entry("drbd", NULL);
+		i = minor_count;
+		while (i--)
+			drbd_delete_device(i);
+		drbd_destroy_mempools();
+	}
+
+	kfree(minor_table);
+
+	unregister_blkdev(DRBD_MAJOR, "drbd");
+
+	printk(KERN_INFO "drbd: module cleanup done.\n");
+}
+
+/**
+ * drbd_congested: Returns 1<<BDI_write_congested and/or
+ * 1<<BDI_read_congested if we are congested. This interface is known
+ * to be used by pdflush.
+ */
+static int drbd_congested(void *congested_data, int bdi_bits)
+{
+	struct drbd_conf *mdev = congested_data;
+	struct request_queue *q;
+	unsigned long flags;
+	char reason = '-';
+	int r = 0;
+
+	if (!__inc_ap_bio_cond(mdev)) {
+		/* DRBD has frozen IO */
+		r = bdi_bits;
+		reason = 'd';
+		goto out;
+	}
+
+	if (inc_local(mdev)) {
+		q = bdev_get_queue(mdev->bc->backing_bdev);
+		r = bdi_congested(&q->backing_dev_info, bdi_bits);
+		dec_local(mdev);
+		if (r) {
+			reason = 'b';
+			goto out;
+		}
+	}
+
+	if (bdi_bits & (1 << BDI_write_congested)) {
+		spin_lock_irqsave(&mdev->req_lock, flags); /* no state changes, please */
+		if (mdev->state.conn >= Connected) {
+			struct sock *sk = mdev->data.socket->sk;
+			if (sk->sk_wmem_queued > sk->sk_sndbuf * 4 / 5) {
+				r = (1 << BDI_write_congested);
+				reason = 'n';
+			}
+		}
+		spin_unlock_irqrestore(&mdev->req_lock, flags);
+	}
+
+out:
+	mdev->congestion_reason = reason;
+	return r;
+}
+
+struct drbd_conf *drbd_new_device(unsigned int minor)
+{
+	struct drbd_conf *mdev;
+	struct gendisk *disk;
+	struct request_queue *q;
+
+	mdev = kzalloc(sizeof(struct drbd_conf), GFP_KERNEL);
+	if (!mdev)
+		return NULL;
+
+	mdev->minor = minor;
+
+	drbd_init_set_defaults(mdev);
+
+	q = blk_alloc_queue(GFP_KERNEL);
+	if (!q)
+		goto out_no_q;
+	mdev->rq_queue = q;
+	q->queuedata   = mdev;
+	q->max_segment_size = DRBD_MAX_SEGMENT_SIZE;
+
+	disk = alloc_disk(1);
+	if (!disk)
+		goto out_no_disk;
+	mdev->vdisk = disk;
+
+	set_disk_ro(disk, TRUE);
+
+	disk->queue = q;
+	disk->major = DRBD_MAJOR;
+	disk->first_minor = minor;
+	disk->fops = &drbd_ops;
+	sprintf(disk->disk_name, "drbd%d", minor);
+	disk->private_data = mdev;
+
+	mdev->this_bdev = bdget(MKDEV(DRBD_MAJOR, minor));
+	/* we have no partitions. we contain only ourselves. */
+	mdev->this_bdev->bd_contains = mdev->this_bdev;
+
+	q->backing_dev_info.congested_fn = drbd_congested;
+	q->backing_dev_info.congested_data = mdev;
+
+	blk_queue_make_request(q, drbd_make_request_26);
+	blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
+	blk_queue_merge_bvec(q, drbd_merge_bvec);
+	q->queue_lock = &mdev->req_lock; /* needed since we use */
+		/* plugging on a queue, that actually has no requests! */
+	q->unplug_fn = drbd_unplug_fn;
+
+	mdev->md_io_page = alloc_page(GFP_KERNEL);
+	if (!mdev->md_io_page)
+		goto out_no_io_page;
+
+	if (drbd_bm_init(mdev))
+		goto out_no_bitmap;
+	/* no need to lock access, we are still initializing the module. */
+	if (!tl_init(mdev))
+		goto out_no_tl;
+
+	mdev->app_reads_hash = kzalloc(APP_R_HSIZE*sizeof(void *), GFP_KERNEL);
+	if (!mdev->app_reads_hash)
+		goto out_no_app_reads;
+
+	mdev->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
+	if (!mdev->current_epoch)
+		goto out_no_epoch;
+
+	INIT_LIST_HEAD(&mdev->current_epoch->list);
+	mdev->epochs = 1;
+
+	return mdev;
+
+/* out_whatever_else:
+	kfree(mdev->current_epoch); */
+out_no_epoch:
+	kfree(mdev->app_reads_hash);
+out_no_app_reads:
+	tl_cleanup(mdev);
+out_no_tl:
+	drbd_bm_cleanup(mdev);
+out_no_bitmap:
+	__free_page(mdev->md_io_page);
+out_no_io_page:
+	put_disk(disk);
+out_no_disk:
+	blk_cleanup_queue(q);
+out_no_q:
+	kfree(mdev);
+	return NULL;
+}
+
+/* counterpart of drbd_new_device.
+ * last part of drbd_delete_device. */
+void drbd_free_mdev(struct drbd_conf *mdev)
+{
+	kfree(mdev->current_epoch);
+	kfree(mdev->app_reads_hash);
+	tl_cleanup(mdev);
+	drbd_bm_cleanup(mdev);
+	__free_page(mdev->md_io_page);
+	put_disk(mdev->vdisk);
+	blk_cleanup_queue(mdev->rq_queue);
+	kfree(mdev);
+}
+
+
+int __init drbd_init(void)
+{
+	int err;
+
+#ifdef __arch_um__
+	printk(KERN_INFO "drbd_module = 0x%p core = 0x%p\n",
+	       THIS_MODULE, THIS_MODULE->module_core);
+#endif
+
+	if (sizeof(struct Drbd_HandShake_Packet) != 80) {
+		printk(KERN_ERR
+		       "drbd: never change the size or layout "
+		       "of the HandShake packet.\n");
+		return -EINVAL;
+	}
+
+	if (1 > minor_count || minor_count > 255) {
+		printk(KERN_ERR
+			"drbd: invalid minor_count (%d)\n", minor_count);
+#ifdef MODULE
+		return -EINVAL;
+#else
+		minor_count = 8;
+#endif
+	}
+
+	err = drbd_nl_init();
+	if (err)
+		return err;
+
+	err = register_blkdev(DRBD_MAJOR, "drbd");
+	if (err) {
+		printk(KERN_ERR
+		       "drbd: unable to register block device major %d\n",
+		       DRBD_MAJOR);
+		return err;
+	}
+
+	register_reboot_notifier(&drbd_notifier);
+
+	/*
+	 * allocate all necessary structs
+	 */
+	err = -ENOMEM;
+
+	init_waitqueue_head(&drbd_pp_wait);
+
+	drbd_proc = NULL; /* play safe for drbd_cleanup */
+	minor_table = kzalloc(sizeof(struct drbd_conf *)*minor_count,
+				GFP_KERNEL);
+	if (!minor_table)
+		goto Enomem;
+
+	err = drbd_create_mempools();
+	if (err)
+		goto Enomem;
+
+#if CONFIG_PROC_FS
+	/*
+	 * register with procfs
+	 */
+	drbd_proc = create_proc_entry("drbd",  S_IFREG | S_IRUGO , NULL);
+
+	if (!drbd_proc)	{
+		printk(KERN_ERR "drbd: unable to register proc file\n");
+		goto Enomem;
+	}
+
+	drbd_proc->proc_fops = &drbd_proc_fops;
+	drbd_proc->owner = THIS_MODULE;
+#else
+# error "Currently drbd depends on the proc file system (CONFIG_PROC_FS)"
+#endif
+
+	printk(KERN_INFO "drbd: initialised. "
+	       "Version: " REL_VERSION " (api:%d/proto:%d-%d)\n",
+	       API_VERSION, PRO_VERSION_MIN, PRO_VERSION_MAX);
+	printk(KERN_INFO "drbd: %s\n", drbd_buildtag());
+	printk(KERN_INFO "drbd: registered as block device major %d\n",
+		DRBD_MAJOR);
+	printk(KERN_INFO "drbd: minor_table @ 0x%p\n", minor_table);
+
+	return 0; /* Success! */
+
+Enomem:
+	drbd_cleanup();
+	if (err == -ENOMEM)
+		/* currently always the case */
+		printk(KERN_ERR "drbd: ran out of memory\n");
+	else
+		printk(KERN_ERR "drbd: initialization failure\n");
+	return err;
+}
+
+void drbd_free_bc(struct drbd_backing_dev *bc)
+{
+	if (bc == NULL)
+		return;
+
+	bd_release(bc->backing_bdev);
+	bd_release(bc->md_bdev);
+
+	fput(bc->lo_file);
+	fput(bc->md_file);
+
+	kfree(bc);
+}
+
+void drbd_free_sock(struct drbd_conf *mdev)
+{
+	if (mdev->data.socket) {
+		sock_release(mdev->data.socket);
+		mdev->data.socket = NULL;
+	}
+	if (mdev->meta.socket) {
+		sock_release(mdev->meta.socket);
+		mdev->meta.socket = NULL;
+	}
+}
+
+
+void drbd_free_resources(struct drbd_conf *mdev)
+{
+	crypto_free_hash(mdev->csums_tfm);
+	mdev->csums_tfm = NULL;
+	crypto_free_hash(mdev->verify_tfm);
+	mdev->verify_tfm = NULL;
+	crypto_free_hash(mdev->cram_hmac_tfm);
+	mdev->cram_hmac_tfm = NULL;
+	crypto_free_hash(mdev->integrity_w_tfm);
+	mdev->integrity_w_tfm = NULL;
+	crypto_free_hash(mdev->integrity_r_tfm);
+	mdev->integrity_r_tfm = NULL;
+
+	drbd_free_sock(mdev);
+
+	__no_warn(local,
+		  drbd_free_bc(mdev->bc);
+		  mdev->bc = NULL;);
+}
+
+/*********************************/
+/* meta data management */
+
+struct meta_data_on_disk {
+	u64 la_size;           /* last agreed size. */
+	u64 uuid[UUID_SIZE];   /* UUIDs. */
+	u64 device_uuid;
+	u64 reserved_u64_1;
+	u32 flags;             /* MDF */
+	u32 magic;
+	u32 md_size_sect;
+	u32 al_offset;         /* offset to this block */
+	u32 al_nr_extents;     /* important for restoring the AL */
+	      /* `-- act_log->nr_elements <-- sync_conf.al_extents */
+	u32 bm_offset;         /* offset to the bitmap, from here */
+	u32 bm_bytes_per_bit;  /* BM_BLOCK_SIZE */
+	u32 reserved_u32[4];
+
+} __attribute((packed));
+
+/**
+ * drbd_md_sync:
+ * Writes the meta data super block if the MD_DIRTY flag bit is set.
+ */
+void drbd_md_sync(struct drbd_conf *mdev)
+{
+	struct meta_data_on_disk *buffer;
+	sector_t sector;
+	int i;
+
+	if (!test_and_clear_bit(MD_DIRTY, &mdev->flags))
+		return;
+	del_timer(&mdev->md_sync_timer);
+
+	/* We use here Failed and not Attaching because we try to write
+	 * metadata even if we detach due to a disk failure! */
+	if (!inc_local_if_state(mdev, Failed))
+		return;
+
+	MTRACE(TraceTypeMDIO, TraceLvlSummary,
+	       INFO("Writing meta data super block now.\n");
+	       );
+
+	mutex_lock(&mdev->md_io_mutex);
+	buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
+	memset(buffer, 0, 512);
+
+	buffer->la_size = cpu_to_be64(drbd_get_capacity(mdev->this_bdev));
+	for (i = Current; i < UUID_SIZE; i++)
+		buffer->uuid[i] = cpu_to_be64(mdev->bc->md.uuid[i]);
+	buffer->flags = cpu_to_be32(mdev->bc->md.flags);
+	buffer->magic = cpu_to_be32(DRBD_MD_MAGIC);
+
+	buffer->md_size_sect  = cpu_to_be32(mdev->bc->md.md_size_sect);
+	buffer->al_offset     = cpu_to_be32(mdev->bc->md.al_offset);
+	buffer->al_nr_extents = cpu_to_be32(mdev->act_log->nr_elements);
+	buffer->bm_bytes_per_bit = cpu_to_be32(BM_BLOCK_SIZE);
+	buffer->device_uuid = cpu_to_be64(mdev->bc->md.device_uuid);
+
+	buffer->bm_offset = cpu_to_be32(mdev->bc->md.bm_offset);
+
+	D_ASSERT(drbd_md_ss__(mdev, mdev->bc) == mdev->bc->md.md_offset);
+	sector = mdev->bc->md.md_offset;
+
+	if (drbd_md_sync_page_io(mdev, mdev->bc, sector, WRITE)) {
+		clear_bit(MD_DIRTY, &mdev->flags);
+	} else {
+		/* this was a try anyways ... */
+		ERR("meta data update failed!\n");
+
+		drbd_chk_io_error(mdev, 1, TRUE);
+		drbd_io_error(mdev, TRUE);
+	}
+
+	/* Update mdev->bc->md.la_size_sect,
+	 * since we updated it on metadata. */
+	mdev->bc->md.la_size_sect = drbd_get_capacity(mdev->this_bdev);
+
+	mutex_unlock(&mdev->md_io_mutex);
+	dec_local(mdev);
+}
+
+/**
+ * drbd_md_read:
+ * @bdev: describes the backing storage and the meta-data storage
+ * Reads the meta data from bdev. Return 0 (NoError) on success, and an
+ * enum ret_codes in case something goes wrong.
+ * Currently only: MDIOError, MDInvalid.
+ */
+int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
+{
+	struct meta_data_on_disk *buffer;
+	int i, rv = NoError;
+
+	if (!inc_local_if_state(mdev, Attaching))
+		return MDIOError;
+
+	mutex_lock(&mdev->md_io_mutex);
+	buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
+
+	if (!drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
+		/* NOTE: cant do normal error processing here as this is
+		   called BEFORE disk is attached */
+		ERR("Error while reading metadata.\n");
+		rv = MDIOError;
+		goto err;
+	}
+
+	if (be32_to_cpu(buffer->magic) != DRBD_MD_MAGIC) {
+		ERR("Error while reading metadata, magic not found.\n");
+		rv = MDInvalid;
+		goto err;
+	}
+	if (be32_to_cpu(buffer->al_offset) != bdev->md.al_offset) {
+		ERR("unexpected al_offset: %d (expected %d)\n",
+		    be32_to_cpu(buffer->al_offset), bdev->md.al_offset);
+		rv = MDInvalid;
+		goto err;
+	}
+	if (be32_to_cpu(buffer->bm_offset) != bdev->md.bm_offset) {
+		ERR("unexpected bm_offset: %d (expected %d)\n",
+		    be32_to_cpu(buffer->bm_offset), bdev->md.bm_offset);
+		rv = MDInvalid;
+		goto err;
+	}
+	if (be32_to_cpu(buffer->md_size_sect) != bdev->md.md_size_sect) {
+		ERR("unexpected md_size: %u (expected %u)\n",
+		    be32_to_cpu(buffer->md_size_sect), bdev->md.md_size_sect);
+		rv = MDInvalid;
+		goto err;
+	}
+
+	if (be32_to_cpu(buffer->bm_bytes_per_bit) != BM_BLOCK_SIZE) {
+		ERR("unexpected bm_bytes_per_bit: %u (expected %u)\n",
+		    be32_to_cpu(buffer->bm_bytes_per_bit), BM_BLOCK_SIZE);
+		rv = MDInvalid;
+		goto err;
+	}
+
+	bdev->md.la_size_sect = be64_to_cpu(buffer->la_size);
+	for (i = Current; i < UUID_SIZE; i++)
+		bdev->md.uuid[i] = be64_to_cpu(buffer->uuid[i]);
+	bdev->md.flags = be32_to_cpu(buffer->flags);
+	mdev->sync_conf.al_extents = be32_to_cpu(buffer->al_nr_extents);
+	bdev->md.device_uuid = be64_to_cpu(buffer->device_uuid);
+
+	if (mdev->sync_conf.al_extents < 7)
+		mdev->sync_conf.al_extents = 127;
+
+ err:
+	mutex_unlock(&mdev->md_io_mutex);
+	dec_local(mdev);
+
+	return rv;
+}
+
+/**
+ * drbd_md_mark_dirty:
+ * Call this function if you change enything that should be written to
+ * the meta-data super block. This function sets MD_DIRTY, and starts a
+ * timer that ensures that within five seconds you have to call drbd_md_sync().
+ */
+void drbd_md_mark_dirty(struct drbd_conf *mdev)
+{
+	set_bit(MD_DIRTY, &mdev->flags);
+	mod_timer(&mdev->md_sync_timer, jiffies + 5*HZ);
+}
+
+
+STATIC void drbd_uuid_move_history(struct drbd_conf *mdev) __must_hold(local)
+{
+	int i;
+
+	for (i = History_start; i < History_end; i++) {
+		mdev->bc->md.uuid[i+1] = mdev->bc->md.uuid[i];
+
+		MTRACE(TraceTypeUuid, TraceLvlAll,
+		       drbd_print_uuid(mdev, i+1);
+			);
+	}
+}
+
+void _drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
+{
+	if (idx == Current) {
+		if (mdev->state.role == Primary)
+			val |= 1;
+		else
+			val &= ~((u64)1);
+
+		drbd_set_ed_uuid(mdev, val);
+	}
+
+	mdev->bc->md.uuid[idx] = val;
+
+	MTRACE(TraceTypeUuid, TraceLvlSummary,
+	       drbd_print_uuid(mdev, idx);
+		);
+
+	drbd_md_mark_dirty(mdev);
+}
+
+
+void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local)
+{
+	if (mdev->bc->md.uuid[idx]) {
+		drbd_uuid_move_history(mdev);
+		mdev->bc->md.uuid[History_start] = mdev->bc->md.uuid[idx];
+		MTRACE(TraceTypeUuid, TraceLvlMetrics,
+		       drbd_print_uuid(mdev, History_start);
+			);
+	}
+	_drbd_uuid_set(mdev, idx, val);
+}
+
+/**
+ * drbd_uuid_new_current:
+ * Creates a new current UUID, and rotates the old current UUID into
+ * the bitmap slot. Causes an incremental resync upon next connect.
+ */
+void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local)
+{
+	u64 val;
+
+	INFO("Creating new current UUID\n");
+	D_ASSERT(mdev->bc->md.uuid[Bitmap] == 0);
+	mdev->bc->md.uuid[Bitmap] = mdev->bc->md.uuid[Current];
+	MTRACE(TraceTypeUuid, TraceLvlMetrics,
+	       drbd_print_uuid(mdev, Bitmap);
+		);
+
+	get_random_bytes(&val, sizeof(u64));
+	_drbd_uuid_set(mdev, Current, val);
+}
+
+void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local)
+{
+	if (mdev->bc->md.uuid[Bitmap] == 0 && val == 0)
+		return;
+
+	if (val == 0) {
+		drbd_uuid_move_history(mdev);
+		mdev->bc->md.uuid[History_start] = mdev->bc->md.uuid[Bitmap];
+		mdev->bc->md.uuid[Bitmap] = 0;
+
+		MTRACE(TraceTypeUuid, TraceLvlMetrics,
+		       drbd_print_uuid(mdev, History_start);
+		       drbd_print_uuid(mdev, Bitmap);
+			);
+	} else {
+		if (mdev->bc->md.uuid[Bitmap])
+			drbd_WARN("bm UUID already set");
+
+		mdev->bc->md.uuid[Bitmap] = val;
+		mdev->bc->md.uuid[Bitmap] &= ~((u64)1);
+
+		MTRACE(TraceTypeUuid, TraceLvlMetrics,
+		       drbd_print_uuid(mdev, Bitmap);
+			);
+	}
+	drbd_md_mark_dirty(mdev);
+}
+
+/**
+ * drbd_bmio_set_n_write:
+ * Is an io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io() that sets
+ * all bits in the bitmap and writes the whole bitmap to stable storage.
+ */
+int drbd_bmio_set_n_write(struct drbd_conf *mdev)
+{
+	int rv = -EIO;
+
+	if (inc_local_if_state(mdev, Attaching)) {
+		drbd_md_set_flag(mdev, MDF_FullSync);
+		drbd_md_sync(mdev);
+		drbd_bm_set_all(mdev);
+
+		rv = drbd_bm_write(mdev);
+
+		if (!rv) {
+			drbd_md_clear_flag(mdev, MDF_FullSync);
+			drbd_md_sync(mdev);
+		}
+
+		dec_local(mdev);
+	}
+
+	return rv;
+}
+
+/**
+ * drbd_bmio_clear_n_write:
+ * Is an io_fn for drbd_queue_bitmap_io() or drbd_bitmap_io() that clears
+ * all bits in the bitmap and writes the whole bitmap to stable storage.
+ */
+int drbd_bmio_clear_n_write(struct drbd_conf *mdev)
+{
+	int rv = -EIO;
+
+	if (inc_local_if_state(mdev, Attaching)) {
+		drbd_bm_clear_all(mdev);
+		rv = drbd_bm_write(mdev);
+		dec_local(mdev);
+	}
+
+	return rv;
+}
+
+STATIC int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+{
+	struct bm_io_work *work = (struct bm_io_work *)w;
+	int rv;
+
+	D_ASSERT(atomic_read(&mdev->ap_bio_cnt) == 0);
+
+	drbd_bm_lock(mdev, work->why);
+	rv = work->io_fn(mdev);
+	drbd_bm_unlock(mdev);
+
+	clear_bit(BITMAP_IO, &mdev->flags);
+	wake_up(&mdev->misc_wait);
+
+	if (work->done)
+		work->done(mdev, rv);
+
+	clear_bit(BITMAP_IO_QUEUED, &mdev->flags);
+	work->why = NULL;
+
+	return 1;
+}
+
+/**
+ * drbd_queue_bitmap_io:
+ * Queues an IO operation on the whole bitmap.
+ * While IO on the bitmap happens we freeze appliation IO thus we ensure
+ * that drbd_set_out_of_sync() can not be called.
+ * This function MUST ONLY be called from worker context.
+ * BAD API ALERT!
+ * It MUST NOT be used while a previous such work is still pending!
+ */
+void drbd_queue_bitmap_io(struct drbd_conf *mdev,
+			  int (*io_fn)(struct drbd_conf *),
+			  void (*done)(struct drbd_conf *, int),
+			  char *why)
+{
+	D_ASSERT(current == mdev->worker.task);
+
+	D_ASSERT(!test_bit(BITMAP_IO_QUEUED, &mdev->flags));
+	D_ASSERT(!test_bit(BITMAP_IO, &mdev->flags));
+	D_ASSERT(list_empty(&mdev->bm_io_work.w.list));
+	if (mdev->bm_io_work.why)
+		ERR("FIXME going to queue '%s' but '%s' still pending?\n",
+			why, mdev->bm_io_work.why);
+
+	mdev->bm_io_work.io_fn = io_fn;
+	mdev->bm_io_work.done = done;
+	mdev->bm_io_work.why = why;
+
+	set_bit(BITMAP_IO, &mdev->flags);
+	if (atomic_read(&mdev->ap_bio_cnt) == 0) {
+		if (list_empty(&mdev->bm_io_work.w.list)) {
+			set_bit(BITMAP_IO_QUEUED, &mdev->flags);
+			drbd_queue_work(&mdev->data.work, &mdev->bm_io_work.w);
+		} else
+			ERR("FIXME avoided double queuing bm_io_work\n");
+	}
+}
+
+/**
+ * drbd_bitmap_io:
+ * Does an IO operation on the bitmap, freezing application IO while that
+ * IO operations runs. This functions MUST NOT be called from worker context.
+ */
+int drbd_bitmap_io(struct drbd_conf *mdev, int (*io_fn)(struct drbd_conf *), char *why)
+{
+	int rv;
+
+	D_ASSERT(current != mdev->worker.task);
+
+	drbd_suspend_io(mdev);
+
+	drbd_bm_lock(mdev, why);
+	rv = io_fn(mdev);
+	drbd_bm_unlock(mdev);
+
+	drbd_resume_io(mdev);
+
+	return rv;
+}
+
+void drbd_md_set_flag(struct drbd_conf *mdev, int flag) __must_hold(local)
+{
+	if ((mdev->bc->md.flags & flag) != flag) {
+		drbd_md_mark_dirty(mdev);
+		mdev->bc->md.flags |= flag;
+	}
+}
+
+void drbd_md_clear_flag(struct drbd_conf *mdev, int flag) __must_hold(local)
+{
+	if ((mdev->bc->md.flags & flag) != 0) {
+		drbd_md_mark_dirty(mdev);
+		mdev->bc->md.flags &= ~flag;
+	}
+}
+int drbd_md_test_flag(struct drbd_backing_dev *bdev, int flag)
+{
+	return (bdev->md.flags & flag) != 0;
+}
+
+STATIC void md_sync_timer_fn(unsigned long data)
+{
+	struct drbd_conf *mdev = (struct drbd_conf *) data;
+
+	drbd_queue_work_front(&mdev->data.work, &mdev->md_sync_work);
+}
+
+STATIC int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+{
+	drbd_WARN("md_sync_timer expired! Worker calls drbd_md_sync().\n");
+	drbd_md_sync(mdev);
+
+	return 1;
+}
+
+#ifdef DRBD_ENABLE_FAULTS
+/* Fault insertion support including random number generator shamelessly
+ * stolen from kernel/rcutorture.c */
+struct fault_random_state {
+	unsigned long state;
+	unsigned long count;
+};
+
+#define FAULT_RANDOM_MULT 39916801  /* prime */
+#define FAULT_RANDOM_ADD	479001701 /* prime */
+#define FAULT_RANDOM_REFRESH 10000
+
+/*
+ * Crude but fast random-number generator.  Uses a linear congruential
+ * generator, with occasional help from get_random_bytes().
+ */
+STATIC unsigned long
+_drbd_fault_random(struct fault_random_state *rsp)
+{
+	long refresh;
+
+	if (--rsp->count < 0) {
+		get_random_bytes(&refresh, sizeof(refresh));
+		rsp->state += refresh;
+		rsp->count = FAULT_RANDOM_REFRESH;
+	}
+	rsp->state = rsp->state * FAULT_RANDOM_MULT + FAULT_RANDOM_ADD;
+	return swahw32(rsp->state);
+}
+
+STATIC char *
+_drbd_fault_str(unsigned int type) {
+	static char *_faults[] = {
+		"Meta-data write",
+		"Meta-data read",
+		"Resync write",
+		"Resync read",
+		"Data write",
+		"Data read",
+		"Data read ahead",
+	};
+
+	return (type < DRBD_FAULT_MAX) ? _faults[type] : "**Unknown**";
+}
+
+unsigned int
+_drbd_insert_fault(struct drbd_conf *mdev, unsigned int type)
+{
+	static struct fault_random_state rrs = {0, 0};
+
+	unsigned int ret = (
+		(fault_devs == 0 ||
+			((1 << mdev_to_minor(mdev)) & fault_devs) != 0) &&
+		(((_drbd_fault_random(&rrs) % 100) + 1) <= fault_rate));
+
+	if (ret) {
+		fault_count++;
+
+		if (printk_ratelimit())
+			drbd_WARN("***Simulating %s failure\n",
+				_drbd_fault_str(type));
+	}
+
+	return ret;
+}
+#endif
+
+#ifdef ENABLE_DYNAMIC_TRACE
+
+STATIC char *_drbd_uuid_str(unsigned int idx)
+{
+	static char *uuid_str[] = {
+		"Current",
+		"Bitmap",
+		"History_start",
+		"History_end",
+		"UUID_SIZE",
+		"UUID_FLAGS",
+	};
+
+	return (idx < EXT_UUID_SIZE) ? uuid_str[idx] : "*Unknown UUID index*";
+}
+
+/* Pretty print a UUID value */
+void drbd_print_uuid(struct drbd_conf *mdev, unsigned int idx) __must_hold(local)
+{
+	INFO(" uuid[%s] now %016llX\n",
+	     _drbd_uuid_str(idx), (unsigned long long)mdev->bc->md.uuid[idx]);
+}
+
+
+/*
+ *
+ * drbd_print_buffer
+ *
+ * This routine dumps binary data to the debugging output. Can be
+ * called at interrupt level.
+ *
+ * Arguments:
+ *
+ *     prefix      - String is output at the beginning of each line output
+ *     flags       - Control operation of the routine. Currently defined
+ *                   Flags are:
+ *                   DBGPRINT_BUFFADDR; if set, each line starts with the
+ *                       virtual address of the line being outupt. If clear,
+ *                       each line starts with the offset from the beginning
+ *                       of the buffer.
+ *     size        - Indicates the size of each entry in the buffer. Supported
+ *                   values are sizeof(char), sizeof(short) and sizeof(int)
+ *     buffer      - Start address of buffer
+ *     buffer_va   - Virtual address of start of buffer (normally the same
+ *                   as Buffer, but having it separate allows it to hold
+ *                   file address for example)
+ *     length      - length of buffer
+ *
+ */
+void
+drbd_print_buffer(const char *prefix, unsigned int flags, int size,
+		  const void *buffer, const void *buffer_va,
+		  unsigned int length)
+
+#define LINE_SIZE       16
+#define LINE_ENTRIES    (int)(LINE_SIZE/size)
+{
+	const unsigned char *pstart;
+	const unsigned char *pstart_va;
+	const unsigned char *pend;
+	char bytes_str[LINE_SIZE*3+8], ascii_str[LINE_SIZE+8];
+	char *pbytes = bytes_str, *pascii = ascii_str;
+	int  offset = 0;
+	long sizemask;
+	int  field_width;
+	int  index;
+	const unsigned char *pend_str;
+	const unsigned char *p;
+	int count;
+
+	/* verify size parameter */
+	if (size != sizeof(char) &&
+	    size != sizeof(short) &&
+	    size != sizeof(int)) {
+		printk(KERN_DEBUG "drbd_print_buffer: "
+			"ERROR invalid size %d\n", size);
+		return;
+	}
+
+	sizemask = size-1;
+	field_width = size*2;
+
+	/* Adjust start/end to be on appropriate boundary for size */
+	buffer = (const char *)((long)buffer & ~sizemask);
+	pend   = (const unsigned char *)
+		(((long)buffer + length + sizemask) & ~sizemask);
+
+	if (flags & DBGPRINT_BUFFADDR) {
+		/* Move start back to nearest multiple of line size,
+		 * if printing address. This results in nicely formatted output
+		 * with addresses being on line size (16) byte boundaries */
+		pstart = (const unsigned char *)((long)buffer & ~(LINE_SIZE-1));
+	} else {
+		pstart = (const unsigned char *)buffer;
+	}
+
+	/* Set value of start VA to print if addresses asked for */
+	pstart_va = (const unsigned char *)buffer_va
+		 - ((const unsigned char *)buffer-pstart);
+
+	/* Calculate end position to nicely align right hand side */
+	pend_str = pstart + (((pend-pstart) + LINE_SIZE-1) & ~(LINE_SIZE-1));
+
+	/* Init strings */
+	*pbytes = *pascii = '\0';
+
+	/* Start at beginning of first line */
+	p = pstart;
+	count = 0;
+
+	while (p < pend_str) {
+		if (p < (const unsigned char *)buffer || p >= pend) {
+			/* Before start of buffer or after end- print spaces */
+			pbytes += sprintf(pbytes, "%*c ", field_width, ' ');
+			pascii += sprintf(pascii, "%*c", size, ' ');
+			p += size;
+		} else {
+			/* Add hex and ascii to strings */
+			int val;
+			switch (size) {
+			default:
+			case 1:
+				val = *(unsigned char *)p;
+				break;
+			case 2:
+				val = *(unsigned short *)p;
+				break;
+			case 4:
+				val = *(unsigned int *)p;
+				break;
+			}
+
+			pbytes += sprintf(pbytes, "%0*x ", field_width, val);
+
+			for (index = size; index; index--) {
+				*pascii++ = isprint(*p) ? *p : '.';
+				p++;
+			}
+		}
+
+		count++;
+
+		if (count == LINE_ENTRIES || p >= pend_str) {
+			/* Null terminate and print record */
+			*pascii = '\0';
+			printk(KERN_DEBUG "%s%8.8lx: %*s|%*s|\n",
+			       prefix,
+			       (flags & DBGPRINT_BUFFADDR)
+			       ? (long)pstart_va:(long)offset,
+			       LINE_ENTRIES*(field_width+1), bytes_str,
+			       LINE_SIZE, ascii_str);
+
+			/* Move onto next line */
+			pstart_va += (p-pstart);
+			pstart = p;
+			count  = 0;
+			offset += LINE_SIZE;
+
+			/* Re-init strings */
+			pbytes = bytes_str;
+			pascii = ascii_str;
+			*pbytes = *pascii = '\0';
+		}
+	}
+}
+
+#define PSM(A)							\
+do {								\
+	if (mask.A) {						\
+		int i = snprintf(p, len, " " #A "( %s )",	\
+				A##s_to_name(val.A));		\
+		if (i >= len)					\
+			return op;				\
+		p += i;						\
+		len -= i;					\
+	}							\
+} while (0)
+
+STATIC char *dump_st(char *p, int len, union drbd_state_t mask, union drbd_state_t val)
+{
+	char *op = p;
+	*p = '\0';
+	PSM(role);
+	PSM(peer);
+	PSM(conn);
+	PSM(disk);
+	PSM(pdsk);
+
+	return op;
+}
+
+#define INFOP(fmt, args...) \
+do { \
+	if (trace_level >= TraceLvlAll) { \
+		INFO("%s:%d: %s [%d] %s %s " fmt , \
+		     file, line, current->comm, current->pid, \
+		     sockname, recv ? "<<<" : ">>>" , \
+		     ## args); \
+	} else { \
+		INFO("%s %s " fmt, sockname, \
+		     recv ? "<<<" : ">>>" , \
+		     ## args); \
+	} \
+} while (0)
+
+STATIC char *_dump_block_id(u64 block_id, char *buff)
+{
+	if (is_syncer_block_id(block_id))
+		strcpy(buff, "SyncerId");
+	else
+		sprintf(buff, "%llx", (unsigned long long)block_id);
+
+	return buff;
+}
+
+void
+_dump_packet(struct drbd_conf *mdev, struct socket *sock,
+	    int recv, union Drbd_Polymorph_Packet *p, char *file, int line)
+{
+	char *sockname = sock == mdev->meta.socket ? "meta" : "data";
+	int cmd = (recv == 2) ? p->head.command : be16_to_cpu(p->head.command);
+	char tmp[300];
+	union drbd_state_t m, v;
+
+	switch (cmd) {
+	case HandShake:
+		INFOP("%s (protocol %u-%u)\n", cmdname(cmd),
+			be32_to_cpu(p->HandShake.protocol_min),
+			be32_to_cpu(p->HandShake.protocol_max));
+		break;
+
+	case ReportBitMap: /* don't report this */
+		break;
+
+	case Data:
+		INFOP("%s (sector %llus, id %s, seq %u, f %x)\n", cmdname(cmd),
+		      (unsigned long long)be64_to_cpu(p->Data.sector),
+		      _dump_block_id(p->Data.block_id, tmp),
+		      be32_to_cpu(p->Data.seq_num),
+		      be32_to_cpu(p->Data.dp_flags)
+			);
+		break;
+
+	case DataReply:
+	case RSDataReply:
+		INFOP("%s (sector %llus, id %s)\n", cmdname(cmd),
+		      (unsigned long long)be64_to_cpu(p->Data.sector),
+		      _dump_block_id(p->Data.block_id, tmp)
+			);
+		break;
+
+	case RecvAck:
+	case WriteAck:
+	case RSWriteAck:
+	case DiscardAck:
+	case NegAck:
+	case NegRSDReply:
+		INFOP("%s (sector %llus, size %u, id %s, seq %u)\n",
+			cmdname(cmd),
+		      (long long)be64_to_cpu(p->BlockAck.sector),
+		      be32_to_cpu(p->BlockAck.blksize),
+		      _dump_block_id(p->BlockAck.block_id, tmp),
+		      be32_to_cpu(p->BlockAck.seq_num)
+			);
+		break;
+
+	case DataRequest:
+	case RSDataRequest:
+		INFOP("%s (sector %llus, size %u, id %s)\n", cmdname(cmd),
+		      (long long)be64_to_cpu(p->BlockRequest.sector),
+		      be32_to_cpu(p->BlockRequest.blksize),
+		      _dump_block_id(p->BlockRequest.block_id, tmp)
+			);
+		break;
+
+	case Barrier:
+	case BarrierAck:
+		INFOP("%s (barrier %u)\n", cmdname(cmd), p->Barrier.barrier);
+		break;
+
+	case SyncParam:
+	case SyncParam89:
+		INFOP("%s (rate %u, verify-alg \"%.64s\", csums-alg \"%.64s\")\n",
+			cmdname(cmd), be32_to_cpu(p->SyncParam89.rate),
+			p->SyncParam89.verify_alg, p->SyncParam89.csums_alg);
+		break;
+
+	case ReportUUIDs:
+		INFOP("%s Curr:%016llX, Bitmap:%016llX, "
+		      "HisSt:%016llX, HisEnd:%016llX\n",
+		      cmdname(cmd),
+		      (unsigned long long)be64_to_cpu(p->GenCnt.uuid[Current]),
+		      (unsigned long long)be64_to_cpu(p->GenCnt.uuid[Bitmap]),
+		      (unsigned long long)be64_to_cpu(p->GenCnt.uuid[History_start]),
+		      (unsigned long long)be64_to_cpu(p->GenCnt.uuid[History_end]));
+		break;
+
+	case ReportSizes:
+		INFOP("%s (d %lluMiB, u %lluMiB, c %lldMiB, "
+		      "max bio %x, q order %x)\n",
+		      cmdname(cmd),
+		      (long long)(be64_to_cpu(p->Sizes.d_size)>>(20-9)),
+		      (long long)(be64_to_cpu(p->Sizes.u_size)>>(20-9)),
+		      (long long)(be64_to_cpu(p->Sizes.c_size)>>(20-9)),
+		      be32_to_cpu(p->Sizes.max_segment_size),
+		      be32_to_cpu(p->Sizes.queue_order_type));
+		break;
+
+	case ReportState:
+		v.i = be32_to_cpu(p->State.state);
+		m.i = 0xffffffff;
+		dump_st(tmp, sizeof(tmp), m, v);
+		INFOP("%s (s %x {%s})\n", cmdname(cmd), v.i, tmp);
+		break;
+
+	case StateChgRequest:
+		m.i = be32_to_cpu(p->ReqState.mask);
+		v.i = be32_to_cpu(p->ReqState.val);
+		dump_st(tmp, sizeof(tmp), m, v);
+		INFOP("%s (m %x v %x {%s})\n", cmdname(cmd), m.i, v.i, tmp);
+		break;
+
+	case StateChgReply:
+		INFOP("%s (ret %x)\n", cmdname(cmd),
+		      be32_to_cpu(p->RqSReply.retcode));
+		break;
+
+	case Ping:
+	case PingAck:
+		/*
+		 * Dont trace pings at summary level
+		 */
+		if (trace_level < TraceLvlAll)
+			break;
+		/* fall through... */
+	default:
+		INFOP("%s (%u)\n", cmdname(cmd), cmd);
+		break;
+	}
+}
+
+/* Debug routine to dump info about bio */
+
+void _dump_bio(const char *pfx, struct drbd_conf *mdev, struct bio *bio, int complete, struct drbd_request *r)
+{
+#ifdef CONFIG_LBD
+#define SECTOR_FORMAT "%Lx"
+#else
+#define SECTOR_FORMAT "%lx"
+#endif
+#define SECTOR_SHIFT 9
+
+	unsigned long lowaddr = (unsigned long)(bio->bi_sector << SECTOR_SHIFT);
+	char *faddr = (char *)(lowaddr);
+	char rb[sizeof(void *)*2+6] = { 0, };
+	struct bio_vec *bvec;
+	int segno;
+
+	const int rw = bio->bi_rw;
+	const int biorw      = (rw & (RW_MASK|RWA_MASK));
+	const int biobarrier = (rw & (1<<BIO_RW_BARRIER));
+	const int biosync    =
+#ifdef BIO_RW_UNPLUG
+		rw & ((1<<BIO_RW_UNPLUG) | (1<<BIO_RW_SYNCIO));
+#else
+		rw & (1<<BIO_RW_SYNC);
+#endif
+
+	if (r)
+		sprintf(rb, "Req:%p ", r);
+
+	INFO("%s %s:%s%s%s Bio:%p %s- %soffset " SECTOR_FORMAT ", size %x\n",
+	     complete ? "<<<" : ">>>",
+	     pfx,
+	     biorw == WRITE ? "Write" : "Read",
+	     biobarrier ? " : B" : "",
+	     biosync ? " : S" : "",
+	     bio,
+	     rb,
+	     complete ? (drbd_bio_uptodate(bio) ? "Success, " : "Failed, ") : "",
+	     bio->bi_sector << SECTOR_SHIFT,
+	     bio->bi_size);
+
+	if (trace_level >= TraceLvlMetrics &&
+	    ((biorw == WRITE) ^ complete)) {
+		printk(KERN_DEBUG "  ind     page   offset   length\n");
+		__bio_for_each_segment(bvec, bio, segno, 0) {
+			printk(KERN_DEBUG "  [%d] %p %8.8x %8.8x\n", segno,
+			       bvec->bv_page, bvec->bv_offset, bvec->bv_len);
+
+			if (trace_level >= TraceLvlAll) {
+				char *bvec_buf;
+				unsigned long flags;
+
+				bvec_buf = bvec_kmap_irq(bvec, &flags);
+
+				drbd_print_buffer("    ", DBGPRINT_BUFFADDR, 1,
+						  bvec_buf,
+						  faddr,
+						  (bvec->bv_len <= 0x80)
+						  ? bvec->bv_len : 0x80);
+
+				bvec_kunmap_irq(bvec_buf, &flags);
+
+				if (bvec->bv_len > 0x40)
+					printk(KERN_DEBUG "    ....\n");
+
+				faddr += bvec->bv_len;
+			}
+		}
+	}
+}
+#endif
+
+module_init(drbd_init)
+module_exit(drbd_cleanup)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/