Merge branch 'drbd-8.4_ed6' into for-3.8-drivers-drbd-8.4_ed6
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 9b833e0..52de26d 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -56,14 +56,6 @@
 
 #include "drbd_vli.h"
 
-struct after_state_chg_work {
-	struct drbd_work w;
-	union drbd_state os;
-	union drbd_state ns;
-	enum chg_state_flags flags;
-	struct completion *done;
-};
-
 static DEFINE_MUTEX(drbd_main_mutex);
 int drbdd_init(struct drbd_thread *);
 int drbd_worker(struct drbd_thread *);
@@ -72,21 +64,17 @@
 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 os,
-			   union drbd_state ns, enum chg_state_flags flags);
-static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+static int w_md_sync(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);
-static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused);
-static void _tl_clear(struct drbd_conf *mdev);
+static int w_bitmap_io(struct drbd_work *w, int unused);
+static int w_go_diskless(struct drbd_work *w, int unused);
 
 MODULE_AUTHOR("Philipp Reisner <phil@linbit.com>, "
 	      "Lars Ellenberg <lars@linbit.com>");
 MODULE_DESCRIPTION("drbd - Distributed Replicated Block Device v" REL_VERSION);
 MODULE_VERSION(REL_VERSION);
 MODULE_LICENSE("GPL");
-MODULE_PARM_DESC(minor_count, "Maximum number of drbd devices ("
+MODULE_PARM_DESC(minor_count, "Approximate number of drbd devices ("
 		 __stringify(DRBD_MINOR_COUNT_MIN) "-" __stringify(DRBD_MINOR_COUNT_MAX) ")");
 MODULE_ALIAS_BLOCKDEV_MAJOR(DRBD_MAJOR);
 
@@ -98,7 +86,6 @@
 module_param(minor_count, uint, 0444);
 module_param(disable_sendpage, bool, 0644);
 module_param(allow_oos, bool, 0);
-module_param(cn_idx, uint, 0444);
 module_param(proc_details, int, 0644);
 
 #ifdef CONFIG_DRBD_FAULT_INJECTION
@@ -120,7 +107,6 @@
 unsigned int minor_count = DRBD_MINOR_COUNT_DEF;
 bool disable_sendpage;
 bool allow_oos;
-unsigned int cn_idx = CN_IDX_DRBD;
 int proc_details;       /* Detail level in proc drbd*/
 
 /* Module parameter for setting the user mode helper program
@@ -132,10 +118,11 @@
 /* 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 idr minors;
+struct list_head drbd_tconns;  /* list of struct drbd_tconn */
 
 struct kmem_cache *drbd_request_cache;
-struct kmem_cache *drbd_ee_cache;	/* epoch entries */
+struct kmem_cache *drbd_ee_cache;	/* peer requests */
 struct kmem_cache *drbd_bm_ext_cache;	/* bitmap extents */
 struct kmem_cache *drbd_al_ext_cache;	/* activity log extents */
 mempool_t *drbd_request_mempool;
@@ -164,10 +151,15 @@
 
 struct bio *bio_alloc_drbd(gfp_t gfp_mask)
 {
+	struct bio *bio;
+
 	if (!drbd_md_io_bio_set)
 		return bio_alloc(gfp_mask, 1);
 
-	return bio_alloc_bioset(gfp_mask, 1, drbd_md_io_bio_set);
+	bio = bio_alloc_bioset(gfp_mask, 1, drbd_md_io_bio_set);
+	if (!bio)
+		return NULL;
+	return bio;
 }
 
 #ifdef __CHECKER__
@@ -190,158 +182,87 @@
 #endif
 
 /**
- * DOC: The transfer log
- *
- * The transfer log is a single linked list of &struct drbd_tl_epoch objects.
- * mdev->newest_tle points to the head, mdev->oldest_tle points to the tail
- * of the list. There is always at least one &struct drbd_tl_epoch object.
- *
- * Each &struct drbd_tl_epoch has a circular double linked list of requests
- * attached.
- */
-static int tl_init(struct drbd_conf *mdev)
-{
-	struct drbd_tl_epoch *b;
-
-	/* during device minor initialization, we may well use GFP_KERNEL */
-	b = kmalloc(sizeof(struct drbd_tl_epoch), 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_writes = 0;
-	b->w.cb = NULL; /* if this is != NULL, we need to dec_ap_pending in tl_clear */
-
-	mdev->oldest_tle = b;
-	mdev->newest_tle = b;
-	INIT_LIST_HEAD(&mdev->out_of_sequence_requests);
-	INIT_LIST_HEAD(&mdev->barrier_acked_requests);
-
-	mdev->tl_hash = NULL;
-	mdev->tl_hash_s = 0;
-
-	return 1;
-}
-
-static void tl_cleanup(struct drbd_conf *mdev)
-{
-	D_ASSERT(mdev->oldest_tle == mdev->newest_tle);
-	D_ASSERT(list_empty(&mdev->out_of_sequence_requests));
-	kfree(mdev->oldest_tle);
-	mdev->oldest_tle = NULL;
-	kfree(mdev->unused_spare_tle);
-	mdev->unused_spare_tle = NULL;
-	kfree(mdev->tl_hash);
-	mdev->tl_hash = NULL;
-	mdev->tl_hash_s = 0;
-}
-
-/**
- * _tl_add_barrier() - Adds a barrier to the transfer log
- * @mdev:	DRBD device.
- * @new:	Barrier to be added before the current head of the TL.
- *
- * The caller must hold the req_lock.
- */
-void _tl_add_barrier(struct drbd_conf *mdev, struct drbd_tl_epoch *new)
-{
-	struct drbd_tl_epoch *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_writes = 0;
-
-	newest_before = mdev->newest_tle;
-	new->br_number = newest_before->br_number+1;
-	if (mdev->newest_tle != new) {
-		mdev->newest_tle->next = new;
-		mdev->newest_tle = new;
-	}
-}
-
-/**
- * tl_release() - Free or recycle the oldest &struct drbd_tl_epoch object of the TL
- * @mdev:	DRBD device.
+ * tl_release() - mark as BARRIER_ACKED all requests in the corresponding transfer log epoch
+ * @tconn:	DRBD connection.
  * @barrier_nr:	Expected identifier of the DRBD write barrier packet.
  * @set_size:	Expected number of requests before that barrier.
  *
  * In case the passed barrier_nr or set_size does not match the oldest
- * &struct drbd_tl_epoch objects this function will cause a termination
- * of the connection.
+ * epoch of not yet barrier-acked requests, this function will cause a
+ * termination of the connection.
  */
-void tl_release(struct drbd_conf *mdev, unsigned int barrier_nr,
-		       unsigned int set_size)
+void tl_release(struct drbd_tconn *tconn, unsigned int barrier_nr,
+		unsigned int set_size)
 {
-	struct drbd_tl_epoch *b, *nob; /* next old barrier */
-	struct list_head *le, *tle;
 	struct drbd_request *r;
+	struct drbd_request *req = NULL;
+	int expect_epoch = 0;
+	int expect_size = 0;
 
-	spin_lock_irq(&mdev->req_lock);
+	spin_lock_irq(&tconn->req_lock);
 
-	b = mdev->oldest_tle;
+	/* find oldest not yet barrier-acked write request,
+	 * count writes in its epoch. */
+	list_for_each_entry(r, &tconn->transfer_log, tl_requests) {
+		const unsigned s = r->rq_state;
+		if (!req) {
+			if (!(s & RQ_WRITE))
+				continue;
+			if (!(s & RQ_NET_MASK))
+				continue;
+			if (s & RQ_NET_DONE)
+				continue;
+			req = r;
+			expect_epoch = req->epoch;
+			expect_size ++;
+		} else {
+			if (r->epoch != expect_epoch)
+				break;
+			if (!(s & RQ_WRITE))
+				continue;
+			/* if (s & RQ_DONE): not expected */
+			/* if (!(s & RQ_NET_MASK)): not expected */
+			expect_size++;
+		}
+	}
 
 	/* first some paranoia code */
-	if (b == NULL) {
-		dev_err(DEV, "BAD! BarrierAck #%u received, but no epoch in tl!?\n",
-			barrier_nr);
+	if (req == NULL) {
+		conn_err(tconn, "BAD! BarrierAck #%u received, but no epoch in tl!?\n",
+			 barrier_nr);
 		goto bail;
 	}
-	if (b->br_number != barrier_nr) {
-		dev_err(DEV, "BAD! BarrierAck #%u received, expected #%u!\n",
-			barrier_nr, b->br_number);
-		goto bail;
-	}
-	if (b->n_writes != set_size) {
-		dev_err(DEV, "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n",
-			barrier_nr, set_size, b->n_writes);
+	if (expect_epoch != barrier_nr) {
+		conn_err(tconn, "BAD! BarrierAck #%u received, expected #%u!\n",
+			 barrier_nr, expect_epoch);
 		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);
-	}
-	/* 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 bug 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_splice_init(&b->requests, &mdev->barrier_acked_requests);
-
-	nob = b->next;
-	if (drbd_test_and_clear_flag(mdev, CREATE_BARRIER)) {
-		_tl_add_barrier(mdev, b);
-		if (nob)
-			mdev->oldest_tle = nob;
-		/* if nob == NULL b was the only barrier, and becomes the new
-		   barrier. Therefore mdev->oldest_tle points already to b */
-	} else {
-		D_ASSERT(nob != NULL);
-		mdev->oldest_tle = nob;
-		kfree(b);
+	if (expect_size != set_size) {
+		conn_err(tconn, "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n",
+			 barrier_nr, set_size, expect_size);
+		goto bail;
 	}
 
-	spin_unlock_irq(&mdev->req_lock);
-	dec_ap_pending(mdev);
+	/* Clean up list of requests processed during current epoch. */
+	/* this extra list walk restart is paranoia,
+	 * to catch requests being barrier-acked "unexpectedly".
+	 * It usually should find the same req again, or some READ preceding it. */
+	list_for_each_entry(req, &tconn->transfer_log, tl_requests)
+		if (req->epoch == expect_epoch)
+			break;
+	list_for_each_entry_safe_from(req, r, &tconn->transfer_log, tl_requests) {
+		if (req->epoch != expect_epoch)
+			break;
+		_req_mod(req, BARRIER_ACKED);
+	}
+	spin_unlock_irq(&tconn->req_lock);
 
 	return;
 
 bail:
-	spin_unlock_irq(&mdev->req_lock);
-	drbd_force_state(mdev, NS(conn, C_PROTOCOL_ERROR));
+	spin_unlock_irq(&tconn->req_lock);
+	conn_request_state(tconn, NS(conn, C_PROTOCOL_ERROR), CS_HARD);
 }
 
 
@@ -350,85 +271,24 @@
  * @mdev:	DRBD device.
  * @what:       The action/event to perform with all request objects
  *
- * @what might be one of connection_lost_while_pending, resend, fail_frozen_disk_io,
- * restart_frozen_disk_io.
+ * @what might be one of CONNECTION_LOST_WHILE_PENDING, RESEND, FAIL_FROZEN_DISK_IO,
+ * RESTART_FROZEN_DISK_IO.
  */
-static void _tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
+/* must hold resource->req_lock */
+void _tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what)
 {
-	struct drbd_tl_epoch *b, *tmp, **pn;
-	struct list_head *le, *tle, carry_reads;
-	struct drbd_request *req;
-	int rv, n_writes, n_reads;
+	struct drbd_request *req, *r;
 
-	b = mdev->oldest_tle;
-	pn = &mdev->oldest_tle;
-	while (b) {
-		n_writes = 0;
-		n_reads = 0;
-		INIT_LIST_HEAD(&carry_reads);
-		list_for_each_safe(le, tle, &b->requests) {
-			req = list_entry(le, struct drbd_request, tl_requests);
-			rv = _req_mod(req, what);
-
-			n_writes += (rv & MR_WRITE) >> MR_WRITE_SHIFT;
-			n_reads  += (rv & MR_READ) >> MR_READ_SHIFT;
-		}
-		tmp = b->next;
-
-		if (n_writes) {
-			if (what == resend) {
-				b->n_writes = n_writes;
-				if (b->w.cb == NULL) {
-					b->w.cb = w_send_barrier;
-					inc_ap_pending(mdev);
-					drbd_set_flag(mdev, CREATE_BARRIER);
-				}
-
-				drbd_queue_work(&mdev->data.work, &b->w);
-			}
-			pn = &b->next;
-		} else {
-			if (n_reads)
-				list_add(&carry_reads, &b->requests);
-			/* 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_tle) {
-				/* recycle, but reinit! */
-				D_ASSERT(tmp == NULL);
-				INIT_LIST_HEAD(&b->requests);
-				list_splice(&carry_reads, &b->requests);
-				INIT_LIST_HEAD(&b->w.list);
-				b->w.cb = NULL;
-				b->br_number = net_random();
-				b->n_writes = 0;
-
-				*pn = b;
-				break;
-			}
-			*pn = tmp;
-			kfree(b);
-		}
-		b = tmp;
-		list_splice(&carry_reads, &b->requests);
-	}
-
-	/* Actions operating on the disk state, also want to work on
-	   requests that got barrier acked. */
-
-	list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
-		req = list_entry(le, struct drbd_request, tl_requests);
+	list_for_each_entry_safe(req, r, &tconn->transfer_log, tl_requests)
 		_req_mod(req, what);
-	}
 }
 
+void tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what)
+{
+	spin_lock_irq(&tconn->req_lock);
+	_tl_restart(tconn, what);
+	spin_unlock_irq(&tconn->req_lock);
+}
 
 /**
  * tl_clear() - Clears all requests and &struct drbd_tl_epoch objects out of the TL
@@ -438,43 +298,9 @@
  * by the requests on the transfer gets marked as our of sync. Called from the
  * receiver thread and the worker thread.
  */
-void tl_clear(struct drbd_conf *mdev)
+void tl_clear(struct drbd_tconn *tconn)
 {
-	spin_lock_irq(&mdev->req_lock);
-	_tl_clear(mdev);
-	spin_unlock_irq(&mdev->req_lock);
-}
-
-static void _tl_clear(struct drbd_conf *mdev)
-{
-	struct list_head *le, *tle;
-	struct drbd_request *r;
-
-	_tl_restart(mdev, connection_lost_while_pending);
-
-	/* 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);
-		/* It would be nice to complete outside of spinlock.
-		 * But this is easier for now. */
-		_req_mod(r, connection_lost_while_pending);
-	}
-
-	/* ensure bit indicating barrier is required is clear */
-	drbd_clear_flag(mdev, CREATE_BARRIER);
-
-	memset(mdev->app_reads_hash, 0, APP_R_HSIZE*sizeof(void *));
-
-}
-
-void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
-{
-	spin_lock_irq(&mdev->req_lock);
-	_tl_restart(mdev, what);
-	spin_unlock_irq(&mdev->req_lock);
+	tl_restart(tconn, CONNECTION_LOST_WHILE_PENDING);
 }
 
 /**
@@ -483,1392 +309,131 @@
  */
 void tl_abort_disk_io(struct drbd_conf *mdev)
 {
-	struct drbd_tl_epoch *b;
-	struct list_head *le, *tle;
-	struct drbd_request *req;
+	struct drbd_tconn *tconn = mdev->tconn;
+	struct drbd_request *req, *r;
 
-	spin_lock_irq(&mdev->req_lock);
-	b = mdev->oldest_tle;
-	while (b) {
-		list_for_each_safe(le, tle, &b->requests) {
-			req = list_entry(le, struct drbd_request, tl_requests);
-			if (!(req->rq_state & RQ_LOCAL_PENDING))
-				continue;
-			_req_mod(req, abort_disk_io);
-		}
-		b = b->next;
-	}
-
-	list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
-		req = list_entry(le, struct drbd_request, tl_requests);
+	spin_lock_irq(&tconn->req_lock);
+	list_for_each_entry_safe(req, r, &tconn->transfer_log, tl_requests) {
 		if (!(req->rq_state & RQ_LOCAL_PENDING))
 			continue;
-		_req_mod(req, abort_disk_io);
+		if (req->w.mdev != mdev)
+			continue;
+		_req_mod(req, ABORT_DISK_IO);
 	}
-
-	spin_unlock_irq(&mdev->req_lock);
+	spin_unlock_irq(&tconn->req_lock);
 }
 
-/**
- * cl_wide_st_chg() - true if the state change is a cluster wide one
- * @mdev:	DRBD device.
- * @os:		old (current) state.
- * @ns:		new (wanted) state.
- */
-static int cl_wide_st_chg(struct drbd_conf *mdev,
-			  union drbd_state os, union drbd_state ns)
-{
-	return (os.conn >= C_CONNECTED && ns.conn >= C_CONNECTED &&
-		 ((os.role != R_PRIMARY && ns.role == R_PRIMARY) ||
-		  (os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
-		  (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S) ||
-		  (os.disk != D_FAILED && ns.disk == D_FAILED))) ||
-		(os.conn >= C_CONNECTED && ns.conn == C_DISCONNECTING) ||
-		(os.conn == C_CONNECTED && ns.conn == C_VERIFY_S);
-}
-
-enum drbd_state_rv
-drbd_change_state(struct drbd_conf *mdev, enum chg_state_flags f,
-		  union drbd_state mask, union drbd_state val)
-{
-	unsigned long flags;
-	union drbd_state os, ns;
-	enum drbd_state_rv 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;
-}
-
-/**
- * drbd_force_state() - Impose a change which happens outside our control on our state
- * @mdev:	DRBD device.
- * @mask:	mask of state bits to change.
- * @val:	value of new state bits.
- */
-void drbd_force_state(struct drbd_conf *mdev,
-	union drbd_state mask, union drbd_state val)
-{
-	drbd_change_state(mdev, CS_HARD, mask, val);
-}
-
-static enum drbd_state_rv is_valid_state(struct drbd_conf *, union drbd_state);
-static enum drbd_state_rv is_valid_state_transition(struct drbd_conf *,
-						    union drbd_state,
-						    union drbd_state);
-enum sanitize_state_warnings {
-	NO_WARNING,
-	ABORTED_ONLINE_VERIFY,
-	ABORTED_RESYNC,
-	CONNECTION_LOST_NEGOTIATING,
-	IMPLICITLY_UPGRADED_DISK,
-	IMPLICITLY_UPGRADED_PDSK,
-};
-static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
-				       union drbd_state ns, enum sanitize_state_warnings *warn);
-int drbd_send_state_req(struct drbd_conf *,
-			union drbd_state, union drbd_state);
-
-static enum drbd_state_rv
-_req_st_cond(struct drbd_conf *mdev, union drbd_state mask,
-	     union drbd_state val)
-{
-	union drbd_state os, ns;
-	unsigned long flags;
-	enum drbd_state_rv rv;
-
-	if (drbd_test_and_clear_flag(mdev, CL_ST_CHG_SUCCESS))
-		return SS_CW_SUCCESS;
-
-	if (drbd_test_and_clear_flag(mdev, CL_ST_CHG_FAIL))
-		return SS_CW_FAILED_BY_PEER;
-
-	rv = 0;
-	spin_lock_irqsave(&mdev->req_lock, flags);
-	os = mdev->state;
-	ns.i = (os.i & ~mask.i) | val.i;
-	ns = sanitize_state(mdev, os, ns, NULL);
-
-	if (!cl_wide_st_chg(mdev, os, ns))
-		rv = SS_CW_NO_NEED;
-	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 = SS_UNKNOWN_ERROR; /* cont waiting, otherwise fail. */
-		}
-	}
-	spin_unlock_irqrestore(&mdev->req_lock, flags);
-
-	return rv;
-}
-
-/**
- * drbd_req_state() - Perform an eventually cluster wide state change
- * @mdev:	DRBD device.
- * @mask:	mask of state bits to change.
- * @val:	value of new state bits.
- * @f:		flags
- *
- * Should not be called directly, use drbd_request_state() or
- * _drbd_request_state().
- */
-static enum drbd_state_rv
-drbd_req_state(struct drbd_conf *mdev, union drbd_state mask,
-	       union drbd_state val, enum chg_state_flags f)
-{
-	struct completion done;
-	unsigned long flags;
-	union drbd_state os, ns;
-	enum drbd_state_rv rv;
-
-	init_completion(&done);
-
-	if (f & CS_SERIALIZE)
-		mutex_lock(&mdev->state_mutex);
-
-	spin_lock_irqsave(&mdev->req_lock, flags);
-	os = mdev->state;
-	ns.i = (os.i & ~mask.i) | val.i;
-	ns = sanitize_state(mdev, os, ns, NULL);
-
-	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 & CS_VERBOSE)
-				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_FAILED_BY_PEER;
-			if (f & CS_VERBOSE)
-				print_st_err(mdev, os, ns, rv);
-			goto abort;
-		}
-
-		if (mask.conn == C_MASK && val.conn == C_DISCONNECTING)
-			drbd_set_flag(mdev, DISCONNECT_SENT);
-
-		wait_event(mdev->state_wait,
-			(rv = _req_st_cond(mdev, mask, val)));
-
-		if (rv < SS_SUCCESS) {
-			drbd_state_unlock(mdev);
-			if (f & CS_VERBOSE)
-				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 & CS_WAIT_COMPLETE && rv == SS_SUCCESS) {
-		D_ASSERT(current != mdev->worker.task);
-		wait_for_completion(&done);
-	}
-
-abort:
-	if (f & CS_SERIALIZE)
-		mutex_unlock(&mdev->state_mutex);
-
-	return rv;
-}
-
-/**
- * _drbd_request_state() - Request a state change (with flags)
- * @mdev:	DRBD device.
- * @mask:	mask of state bits to change.
- * @val:	value of new state bits.
- * @f:		flags
- *
- * Cousin of drbd_request_state(), useful with the CS_WAIT_COMPLETE
- * flag, or when logging of failed state change requests is not desired.
- */
-enum drbd_state_rv
-_drbd_request_state(struct drbd_conf *mdev, union drbd_state mask,
-		    union drbd_state val, enum chg_state_flags f)
-{
-	enum drbd_state_rv rv;
-
-	wait_event(mdev->state_wait,
-		   (rv = drbd_req_state(mdev, mask, val, f)) != SS_IN_TRANSIENT_STATE);
-
-	return rv;
-}
-
-static void print_st(struct drbd_conf *mdev, char *name, union drbd_state ns)
-{
-	dev_err(DEV, " %s = { cs:%s ro:%s/%s ds:%s/%s %c%c%c%c }\n",
-	    name,
-	    drbd_conn_str(ns.conn),
-	    drbd_role_str(ns.role),
-	    drbd_role_str(ns.peer),
-	    drbd_disk_str(ns.disk),
-	    drbd_disk_str(ns.pdsk),
-	    is_susp(ns) ? '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 os,
-	          union drbd_state ns, enum drbd_state_rv err)
-{
-	if (err == SS_IN_TRANSIENT_STATE)
-		return;
-	dev_err(DEV, "State change failed: %s\n", drbd_set_st_err_str(err));
-	print_st(mdev, " state", os);
-	print_st(mdev, "wanted", ns);
-}
-
-
-/**
- * is_valid_state() - Returns an SS_ error code if ns is not valid
- * @mdev:	DRBD device.
- * @ns:		State to consider.
- */
-static enum drbd_state_rv
-is_valid_state(struct drbd_conf *mdev, union drbd_state ns)
-{
-	/* See drbd_state_sw_errors in drbd_strings.c */
-
-	enum drbd_fencing_p fp;
-	enum drbd_state_rv rv = SS_SUCCESS;
-
-	fp = FP_DONT_CARE;
-	if (get_ldev(mdev)) {
-		fp = mdev->ldev->dc.fencing;
-		put_ldev(mdev);
-	}
-
-	if (get_net_conf(mdev)) {
-		if (!mdev->net_conf->two_primaries &&
-		    ns.role == R_PRIMARY && ns.peer == R_PRIMARY)
-			rv = SS_TWO_PRIMARIES;
-		put_net_conf(mdev);
-	}
-
-	if (rv <= 0)
-		/* already found a reason to abort */;
-	else if (ns.role == R_SECONDARY && mdev->open_cnt)
-		rv = SS_DEVICE_IN_USE;
-
-	else if (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.disk < D_UP_TO_DATE)
-		rv = SS_NO_UP_TO_DATE_DISK;
-
-	else if (fp >= FP_RESOURCE &&
-		 ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk >= D_UNKNOWN)
-		rv = SS_PRIMARY_NOP;
-
-	else if (ns.role == R_PRIMARY && ns.disk <= D_INCONSISTENT && ns.pdsk <= D_INCONSISTENT)
-		rv = SS_NO_UP_TO_DATE_DISK;
-
-	else if (ns.conn > C_CONNECTED && ns.disk < D_INCONSISTENT)
-		rv = SS_NO_LOCAL_DISK;
-
-	else if (ns.conn > C_CONNECTED && ns.pdsk < D_INCONSISTENT)
-		rv = SS_NO_REMOTE_DISK;
-
-	else if (ns.conn > C_CONNECTED && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE)
-		rv = SS_NO_UP_TO_DATE_DISK;
-
-	else if ((ns.conn == C_CONNECTED ||
-		  ns.conn == C_WF_BITMAP_S ||
-		  ns.conn == C_SYNC_SOURCE ||
-		  ns.conn == C_PAUSED_SYNC_S) &&
-		  ns.disk == D_OUTDATED)
-		rv = SS_CONNECTED_OUTDATES;
-
-	else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
-		 (mdev->sync_conf.verify_alg[0] == 0))
-		rv = SS_NO_VERIFY_ALG;
-
-	else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
-		  mdev->agreed_pro_version < 88)
-		rv = SS_NOT_SUPPORTED;
-
-	else if (ns.conn >= C_CONNECTED && ns.pdsk == D_UNKNOWN)
-		rv = SS_CONNECTED_OUTDATES;
-
-	return rv;
-}
-
-/**
- * is_valid_state_transition() - Returns an SS_ error code if the state transition is not possible
- * @mdev:	DRBD device.
- * @ns:		new state.
- * @os:		old state.
- */
-static enum drbd_state_rv
-is_valid_state_transition(struct drbd_conf *mdev, union drbd_state ns,
-			  union drbd_state os)
-{
-	enum drbd_state_rv rv = SS_SUCCESS;
-
-	if ((ns.conn == C_STARTING_SYNC_T || ns.conn == C_STARTING_SYNC_S) &&
-	    os.conn > C_CONNECTED)
-		rv = SS_RESYNC_RUNNING;
-
-	if (ns.conn == C_DISCONNECTING && os.conn == C_STANDALONE)
-		rv = SS_ALREADY_STANDALONE;
-
-	if (ns.disk > D_ATTACHING && os.disk == D_DISKLESS)
-		rv = SS_IS_DISKLESS;
-
-	if (ns.conn == C_WF_CONNECTION && os.conn < C_UNCONNECTED)
-		rv = SS_NO_NET_CONFIG;
-
-	if (ns.disk == D_OUTDATED && os.disk < D_OUTDATED && os.disk != D_ATTACHING)
-		rv = SS_LOWER_THAN_OUTDATED;
-
-	if (ns.conn == C_DISCONNECTING && os.conn == C_UNCONNECTED)
-		rv = SS_IN_TRANSIENT_STATE;
-
-	if (ns.conn == os.conn && ns.conn == C_WF_REPORT_PARAMS)
-		rv = SS_IN_TRANSIENT_STATE;
-
-	/* While establishing a connection only allow cstate to change.
-	   Delay/refuse role changes, detach attach etc... */
-	if (drbd_test_flag(mdev, STATE_SENT) &&
-	    !(os.conn == C_WF_REPORT_PARAMS ||
-	      (ns.conn == C_WF_REPORT_PARAMS && os.conn == C_WF_CONNECTION)))
-		rv = SS_IN_TRANSIENT_STATE;
-
-	if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) && os.conn < C_CONNECTED)
-		rv = SS_NEED_CONNECTION;
-
-	if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
-	    ns.conn != os.conn && os.conn > C_CONNECTED)
-		rv = SS_RESYNC_RUNNING;
-
-	if ((ns.conn == C_STARTING_SYNC_S || ns.conn == C_STARTING_SYNC_T) &&
-	    os.conn < C_CONNECTED)
-		rv = SS_NEED_CONNECTION;
-
-	if ((ns.conn == C_SYNC_TARGET || ns.conn == C_SYNC_SOURCE)
-	    && os.conn < C_WF_REPORT_PARAMS)
-		rv = SS_NEED_CONNECTION; /* No NetworkFailure -> SyncTarget etc... */
-
-	return rv;
-}
-
-static void print_sanitize_warnings(struct drbd_conf *mdev, enum sanitize_state_warnings warn)
-{
-	static const char *msg_table[] = {
-		[NO_WARNING] = "",
-		[ABORTED_ONLINE_VERIFY] = "Online-verify aborted.",
-		[ABORTED_RESYNC] = "Resync aborted.",
-		[CONNECTION_LOST_NEGOTIATING] = "Connection lost while negotiating, no data!",
-		[IMPLICITLY_UPGRADED_DISK] = "Implicitly upgraded disk",
-		[IMPLICITLY_UPGRADED_PDSK] = "Implicitly upgraded pdsk",
-	};
-
-	if (warn != NO_WARNING)
-		dev_warn(DEV, "%s\n", msg_table[warn]);
-}
-
-/**
- * sanitize_state() - Resolves implicitly necessary additional changes to a state transition
- * @mdev:	DRBD device.
- * @os:		old state.
- * @ns:		new state.
- * @warn_sync_abort:
- *
- * When we loose connection, we have to set the state of the peers disk (pdsk)
- * to D_UNKNOWN. This rule and many more along those lines are in this function.
- */
-static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
-				       union drbd_state ns, enum sanitize_state_warnings *warn)
-{
-	enum drbd_fencing_p fp;
-	enum drbd_disk_state disk_min, disk_max, pdsk_min, pdsk_max;
-
-	if (warn)
-		*warn = NO_WARNING;
-
-	fp = FP_DONT_CARE;
-	if (get_ldev(mdev)) {
-		fp = mdev->ldev->dc.fencing;
-		put_ldev(mdev);
-	}
-
-	/* Disallow Network errors to configure a device's network part */
-	if ((ns.conn >= C_TIMEOUT && ns.conn <= C_TEAR_DOWN) &&
-	    os.conn <= C_DISCONNECTING)
-		ns.conn = os.conn;
-
-	/* After a network error (+C_TEAR_DOWN) only C_UNCONNECTED or C_DISCONNECTING can follow.
-	 * If you try to go into some Sync* state, that shall fail (elsewhere). */
-	if (os.conn >= C_TIMEOUT && os.conn <= C_TEAR_DOWN &&
-	    ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING && ns.conn <= C_CONNECTED)
-		ns.conn = os.conn;
-
-	/* we cannot fail (again) if we already detached */
-	if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
-		ns.disk = D_DISKLESS;
-
-	/* After C_DISCONNECTING only C_STANDALONE may follow */
-	if (os.conn == C_DISCONNECTING && ns.conn != C_STANDALONE)
-		ns.conn = os.conn;
-
-	if (ns.conn < C_CONNECTED) {
-		ns.peer_isp = 0;
-		ns.peer = R_UNKNOWN;
-		if (ns.pdsk > D_UNKNOWN || ns.pdsk < D_INCONSISTENT)
-			ns.pdsk = D_UNKNOWN;
-	}
-
-	/* Clear the aftr_isp when becoming unconfigured */
-	if (ns.conn == C_STANDALONE && ns.disk == D_DISKLESS && ns.role == R_SECONDARY)
-		ns.aftr_isp = 0;
-
-	/* Abort resync if a disk fails/detaches */
-	if (os.conn > C_CONNECTED && ns.conn > C_CONNECTED &&
-	    (ns.disk <= D_FAILED || ns.pdsk <= D_FAILED)) {
-		if (warn)
-			*warn =	os.conn == C_VERIFY_S || os.conn == C_VERIFY_T ?
-				ABORTED_ONLINE_VERIFY : ABORTED_RESYNC;
-		ns.conn = C_CONNECTED;
-	}
-
-	/* Connection breaks down before we finished "Negotiating" */
-	if (ns.conn < C_CONNECTED && ns.disk == D_NEGOTIATING &&
-	    get_ldev_if_state(mdev, D_NEGOTIATING)) {
-		if (mdev->ed_uuid == mdev->ldev->md.uuid[UI_CURRENT]) {
-			ns.disk = mdev->new_state_tmp.disk;
-			ns.pdsk = mdev->new_state_tmp.pdsk;
-		} else {
-			if (warn)
-				*warn = CONNECTION_LOST_NEGOTIATING;
-			ns.disk = D_DISKLESS;
-			ns.pdsk = D_UNKNOWN;
-		}
-		put_ldev(mdev);
-	}
-
-	/* D_CONSISTENT and D_OUTDATED vanish when we get connected */
-	if (ns.conn >= C_CONNECTED && ns.conn < C_AHEAD) {
-		if (ns.disk == D_CONSISTENT || ns.disk == D_OUTDATED)
-			ns.disk = D_UP_TO_DATE;
-		if (ns.pdsk == D_CONSISTENT || ns.pdsk == D_OUTDATED)
-			ns.pdsk = D_UP_TO_DATE;
-	}
-
-	/* Implications of the connection stat on the disk states */
-	disk_min = D_DISKLESS;
-	disk_max = D_UP_TO_DATE;
-	pdsk_min = D_INCONSISTENT;
-	pdsk_max = D_UNKNOWN;
-	switch ((enum drbd_conns)ns.conn) {
-	case C_WF_BITMAP_T:
-	case C_PAUSED_SYNC_T:
-	case C_STARTING_SYNC_T:
-	case C_WF_SYNC_UUID:
-	case C_BEHIND:
-		disk_min = D_INCONSISTENT;
-		disk_max = D_OUTDATED;
-		pdsk_min = D_UP_TO_DATE;
-		pdsk_max = D_UP_TO_DATE;
-		break;
-	case C_VERIFY_S:
-	case C_VERIFY_T:
-		disk_min = D_UP_TO_DATE;
-		disk_max = D_UP_TO_DATE;
-		pdsk_min = D_UP_TO_DATE;
-		pdsk_max = D_UP_TO_DATE;
-		break;
-	case C_CONNECTED:
-		disk_min = D_DISKLESS;
-		disk_max = D_UP_TO_DATE;
-		pdsk_min = D_DISKLESS;
-		pdsk_max = D_UP_TO_DATE;
-		break;
-	case C_WF_BITMAP_S:
-	case C_PAUSED_SYNC_S:
-	case C_STARTING_SYNC_S:
-	case C_AHEAD:
-		disk_min = D_UP_TO_DATE;
-		disk_max = D_UP_TO_DATE;
-		pdsk_min = D_INCONSISTENT;
-		pdsk_max = D_CONSISTENT; /* D_OUTDATED would be nice. But explicit outdate necessary*/
-		break;
-	case C_SYNC_TARGET:
-		disk_min = D_INCONSISTENT;
-		disk_max = D_INCONSISTENT;
-		pdsk_min = D_UP_TO_DATE;
-		pdsk_max = D_UP_TO_DATE;
-		break;
-	case C_SYNC_SOURCE:
-		disk_min = D_UP_TO_DATE;
-		disk_max = D_UP_TO_DATE;
-		pdsk_min = D_INCONSISTENT;
-		pdsk_max = D_INCONSISTENT;
-		break;
-	case C_STANDALONE:
-	case C_DISCONNECTING:
-	case C_UNCONNECTED:
-	case C_TIMEOUT:
-	case C_BROKEN_PIPE:
-	case C_NETWORK_FAILURE:
-	case C_PROTOCOL_ERROR:
-	case C_TEAR_DOWN:
-	case C_WF_CONNECTION:
-	case C_WF_REPORT_PARAMS:
-	case C_MASK:
-		break;
-	}
-	if (ns.disk > disk_max)
-		ns.disk = disk_max;
-
-	if (ns.disk < disk_min) {
-		if (warn)
-			*warn = IMPLICITLY_UPGRADED_DISK;
-		ns.disk = disk_min;
-	}
-	if (ns.pdsk > pdsk_max)
-		ns.pdsk = pdsk_max;
-
-	if (ns.pdsk < pdsk_min) {
-		if (warn)
-			*warn = IMPLICITLY_UPGRADED_PDSK;
-		ns.pdsk = pdsk_min;
-	}
-
-	if (fp == FP_STONITH &&
-	    (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk > D_OUTDATED) &&
-	    !(os.role == R_PRIMARY && os.conn < C_CONNECTED && os.pdsk > D_OUTDATED))
-		ns.susp_fen = 1; /* Suspend IO while fence-peer handler runs (peer lost) */
-
-	if (mdev->sync_conf.on_no_data == OND_SUSPEND_IO &&
-	    (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE) &&
-	    !(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE))
-		ns.susp_nod = 1; /* Suspend IO while no data available (no accessible data available) */
-
-	if (ns.aftr_isp || ns.peer_isp || ns.user_isp) {
-		if (ns.conn == C_SYNC_SOURCE)
-			ns.conn = C_PAUSED_SYNC_S;
-		if (ns.conn == C_SYNC_TARGET)
-			ns.conn = C_PAUSED_SYNC_T;
-	} else {
-		if (ns.conn == C_PAUSED_SYNC_S)
-			ns.conn = C_SYNC_SOURCE;
-		if (ns.conn == C_PAUSED_SYNC_T)
-			ns.conn = C_SYNC_TARGET;
-	}
-
-	return ns;
-}
-
-/* helper for __drbd_set_state */
-static void set_ov_position(struct drbd_conf *mdev, enum drbd_conns cs)
-{
-	if (mdev->agreed_pro_version < 90)
-		mdev->ov_start_sector = 0;
-	mdev->rs_total = drbd_bm_bits(mdev);
-	mdev->ov_position = 0;
-	if (cs == C_VERIFY_T) {
-		/* starting online verify from an arbitrary position
-		 * does not fit well into the existing protocol.
-		 * on C_VERIFY_T, we initialize ov_left and friends
-		 * implicitly in receive_DataRequest once the
-		 * first P_OV_REQUEST is received */
-		mdev->ov_start_sector = ~(sector_t)0;
-	} else {
-		unsigned long bit = BM_SECT_TO_BIT(mdev->ov_start_sector);
-		if (bit >= mdev->rs_total) {
-			mdev->ov_start_sector =
-				BM_BIT_TO_SECT(mdev->rs_total - 1);
-			mdev->rs_total = 1;
-		} else
-			mdev->rs_total -= bit;
-		mdev->ov_position = mdev->ov_start_sector;
-	}
-	mdev->ov_left = mdev->rs_total;
-}
-
-static void drbd_resume_al(struct drbd_conf *mdev)
-{
-	if (drbd_test_and_clear_flag(mdev, AL_SUSPENDED))
-		dev_info(DEV, "Resumed AL updates\n");
-}
-
-/**
- * __drbd_set_state() - Set a new DRBD state
- * @mdev:	DRBD device.
- * @ns:		new state.
- * @flags:	Flags
- * @done:	Optional completion, that will get completed after the after_state_ch() finished
- *
- * Caller needs to hold req_lock, and global_state_lock. Do not call directly.
- */
-enum drbd_state_rv
-__drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
-	         enum chg_state_flags flags, struct completion *done)
-{
-	union drbd_state os;
-	enum drbd_state_rv rv = SS_SUCCESS;
-	enum sanitize_state_warnings ssw;
-	struct after_state_chg_work *ascw;
-
-	os = mdev->state;
-
-	ns = sanitize_state(mdev, os, ns, &ssw);
-
-	if (ns.i == os.i)
-		return SS_NOTHING_TO_DO;
-
-	if (!(flags & CS_HARD)) {
-		/*  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)
-				rv = is_valid_state_transition(mdev, ns, os);
-		} else
-			rv = is_valid_state_transition(mdev, ns, os);
-	}
-
-	if (rv < SS_SUCCESS) {
-		if (flags & CS_VERBOSE)
-			print_st_err(mdev, os, ns, rv);
-		return rv;
-	}
-
-	print_sanitize_warnings(mdev, ssw);
-
-	{
-	char *pbp, pb[300];
-	pbp = pb;
-	*pbp = 0;
-	if (ns.role != os.role)
-		pbp += sprintf(pbp, "role( %s -> %s ) ",
-			       drbd_role_str(os.role),
-			       drbd_role_str(ns.role));
-	if (ns.peer != os.peer)
-		pbp += sprintf(pbp, "peer( %s -> %s ) ",
-			       drbd_role_str(os.peer),
-			       drbd_role_str(ns.peer));
-	if (ns.conn != os.conn)
-		pbp += sprintf(pbp, "conn( %s -> %s ) ",
-			       drbd_conn_str(os.conn),
-			       drbd_conn_str(ns.conn));
-	if (ns.disk != os.disk)
-		pbp += sprintf(pbp, "disk( %s -> %s ) ",
-			       drbd_disk_str(os.disk),
-			       drbd_disk_str(ns.disk));
-	if (ns.pdsk != os.pdsk)
-		pbp += sprintf(pbp, "pdsk( %s -> %s ) ",
-			       drbd_disk_str(os.pdsk),
-			       drbd_disk_str(ns.pdsk));
-	if (is_susp(ns) != is_susp(os))
-		pbp += sprintf(pbp, "susp( %d -> %d ) ",
-			       is_susp(os),
-			       is_susp(ns));
-	if (ns.aftr_isp != os.aftr_isp)
-		pbp += sprintf(pbp, "aftr_isp( %d -> %d ) ",
-			       os.aftr_isp,
-			       ns.aftr_isp);
-	if (ns.peer_isp != os.peer_isp)
-		pbp += sprintf(pbp, "peer_isp( %d -> %d ) ",
-			       os.peer_isp,
-			       ns.peer_isp);
-	if (ns.user_isp != os.user_isp)
-		pbp += sprintf(pbp, "user_isp( %d -> %d ) ",
-			       os.user_isp,
-			       ns.user_isp);
-	dev_info(DEV, "%s\n", pb);
-	}
-
-	/* solve the race between becoming unconfigured,
-	 * worker doing the cleanup, and
-	 * admin reconfiguring us:
-	 * on (re)configure, first set CONFIG_PENDING,
-	 * then wait for a potentially exiting worker,
-	 * start the worker, and schedule one no_op.
-	 * then proceed with configuration.
-	 */
-	if (ns.disk == D_DISKLESS &&
-	    ns.conn == C_STANDALONE &&
-	    ns.role == R_SECONDARY &&
-	    !drbd_test_and_set_flag(mdev, CONFIG_PENDING))
-		drbd_set_flag(mdev, DEVICE_DYING);
-
-	/* if we are going -> D_FAILED or D_DISKLESS, grab one extra reference
-	 * on the ldev here, to be sure the transition -> D_DISKLESS resp.
-	 * drbd_ldev_destroy() won't happen before our corresponding
-	 * after_state_ch works run, where we put_ldev again. */
-	if ((os.disk != D_FAILED && ns.disk == D_FAILED) ||
-	    (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))
-		atomic_inc(&mdev->local_cnt);
-
-	mdev->state = ns;
-
-	if (os.disk == D_ATTACHING && ns.disk >= D_NEGOTIATING)
-		drbd_print_uuids(mdev, "attached to UUIDs");
-
-	wake_up(&mdev->misc_wait);
-	wake_up(&mdev->state_wait);
-
-	/* Aborted verify run, or we reached the stop sector.
-	 * Log the last position, unless end-of-device. */
-	if ((os.conn == C_VERIFY_S || os.conn == C_VERIFY_T) &&
-	    ns.conn <= C_CONNECTED) {
-		mdev->ov_start_sector =
-			BM_BIT_TO_SECT(drbd_bm_bits(mdev) - mdev->ov_left);
-		if (mdev->ov_left)
-			dev_info(DEV, "Online Verify reached sector %llu\n",
-				(unsigned long long)mdev->ov_start_sector);
-	}
-
-	if ((os.conn == C_PAUSED_SYNC_T || os.conn == C_PAUSED_SYNC_S) &&
-	    (ns.conn == C_SYNC_TARGET  || ns.conn == C_SYNC_SOURCE)) {
-		dev_info(DEV, "Syncer continues.\n");
-		mdev->rs_paused += (long)jiffies
-				  -(long)mdev->rs_mark_time[mdev->rs_last_mark];
-		if (ns.conn == C_SYNC_TARGET)
-			mod_timer(&mdev->resync_timer, jiffies);
-	}
-
-	if ((os.conn == C_SYNC_TARGET  || os.conn == C_SYNC_SOURCE) &&
-	    (ns.conn == C_PAUSED_SYNC_T || ns.conn == C_PAUSED_SYNC_S)) {
-		dev_info(DEV, "Resync suspended\n");
-		mdev->rs_mark_time[mdev->rs_last_mark] = jiffies;
-	}
-
-	if (os.conn == C_CONNECTED &&
-	    (ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T)) {
-		unsigned long now = jiffies;
-		int i;
-
-		set_ov_position(mdev, ns.conn);
-		mdev->rs_start = now;
-		mdev->rs_last_events = 0;
-		mdev->rs_last_sect_ev = 0;
-		mdev->ov_last_oos_size = 0;
-		mdev->ov_last_oos_start = 0;
-
-		for (i = 0; i < DRBD_SYNC_MARKS; i++) {
-			mdev->rs_mark_left[i] = mdev->ov_left;
-			mdev->rs_mark_time[i] = now;
-		}
-
-		drbd_rs_controller_reset(mdev);
-
-		if (ns.conn == C_VERIFY_S) {
-			dev_info(DEV, "Starting Online Verify from sector %llu\n",
-					(unsigned long long)mdev->ov_position);
-			mod_timer(&mdev->resync_timer, jiffies);
-		}
-	}
-
-	if (get_ldev(mdev)) {
-		u32 mdf = mdev->ldev->md.flags & ~(MDF_CONSISTENT|MDF_PRIMARY_IND|
-						 MDF_CONNECTED_IND|MDF_WAS_UP_TO_DATE|
-						 MDF_PEER_OUT_DATED|MDF_CRASHED_PRIMARY);
-
-		if (drbd_test_flag(mdev, CRASHED_PRIMARY))
-			mdf |= MDF_CRASHED_PRIMARY;
-		if (mdev->state.role == R_PRIMARY ||
-		    (mdev->state.pdsk < D_INCONSISTENT && mdev->state.peer == R_PRIMARY))
-			mdf |= MDF_PRIMARY_IND;
-		if (mdev->state.conn > C_WF_REPORT_PARAMS)
-			mdf |= MDF_CONNECTED_IND;
-		if (mdev->state.disk > D_INCONSISTENT)
-			mdf |= MDF_CONSISTENT;
-		if (mdev->state.disk > D_OUTDATED)
-			mdf |= MDF_WAS_UP_TO_DATE;
-		if (mdev->state.pdsk <= D_OUTDATED && mdev->state.pdsk >= D_INCONSISTENT)
-			mdf |= MDF_PEER_OUT_DATED;
-		if (mdf != mdev->ldev->md.flags) {
-			mdev->ldev->md.flags = mdf;
-			drbd_md_mark_dirty(mdev);
-		}
-		if (os.disk < D_CONSISTENT && ns.disk >= D_CONSISTENT)
-			drbd_set_ed_uuid(mdev, mdev->ldev->md.uuid[UI_CURRENT]);
-		put_ldev(mdev);
-	}
-
-	/* Peer was forced D_UP_TO_DATE & R_PRIMARY, consider to resync */
-	if (os.disk == D_INCONSISTENT && os.pdsk == D_INCONSISTENT &&
-	    os.peer == R_SECONDARY && ns.peer == R_PRIMARY)
-		drbd_set_flag(mdev, CONSIDER_RESYNC);
-
-	/* Receiver should clean up itself */
-	if (os.conn != C_DISCONNECTING && ns.conn == C_DISCONNECTING)
-		drbd_thread_stop_nowait(&mdev->receiver);
-
-	/* Now the receiver finished cleaning up itself, it should die */
-	if (os.conn != C_STANDALONE && ns.conn == C_STANDALONE)
-		drbd_thread_stop_nowait(&mdev->receiver);
-
-	/* Upon network failure, we need to restart the receiver. */
-	if (os.conn > C_WF_CONNECTION &&
-	    ns.conn <= C_TEAR_DOWN && ns.conn >= C_TIMEOUT)
-		drbd_thread_restart_nowait(&mdev->receiver);
-
-	/* Resume AL writing if we get a connection */
-	if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
-		drbd_resume_al(mdev);
-
-	/* remember last connect and attach times so request_timer_fn() won't
-	 * kill newly established sessions while we are still trying to thaw
-	 * previously frozen IO */
-	if (os.conn != C_WF_REPORT_PARAMS && ns.conn == C_WF_REPORT_PARAMS)
-		mdev->last_reconnect_jif = jiffies;
-	if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
-	    ns.disk > D_NEGOTIATING)
-		mdev->last_reattach_jif = jiffies;
-
-	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 {
-		dev_warn(DEV, "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 =
-		container_of(w, struct after_state_chg_work, w);
-	after_state_ch(mdev, ascw->os, ascw->ns, ascw->flags);
-	if (ascw->flags & CS_WAIT_COMPLETE) {
-		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) {
-		dev_err(DEV, "Writing the bitmap failed not starting resync.\n");
-		_drbd_request_state(mdev, NS(conn, C_CONNECTED), CS_VERBOSE);
-		return;
-	}
-
-	switch (mdev->state.conn) {
-	case C_STARTING_SYNC_T:
-		_drbd_request_state(mdev, NS(conn, C_WF_SYNC_UUID), CS_VERBOSE);
-		break;
-	case C_STARTING_SYNC_S:
-		drbd_start_resync(mdev, C_SYNC_SOURCE);
-		break;
-	}
-}
-
-int drbd_bitmap_io_from_worker(struct drbd_conf *mdev,
-		int (*io_fn)(struct drbd_conf *),
-		char *why, enum bm_flag flags)
-{
-	int rv;
-
-	D_ASSERT(current == mdev->worker.task);
-
-	/* open coded non-blocking drbd_suspend_io(mdev); */
-	drbd_set_flag(mdev, SUSPEND_IO);
-
-	drbd_bm_lock(mdev, why, flags);
-	rv = io_fn(mdev);
-	drbd_bm_unlock(mdev);
-
-	drbd_resume_io(mdev);
-
-	return rv;
-}
-
-/**
- * after_state_ch() - Perform after state change actions that may sleep
- * @mdev:	DRBD device.
- * @os:		old state.
- * @ns:		new state.
- * @flags:	Flags
- */
-static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
-			   union drbd_state ns, enum chg_state_flags flags)
-{
-	enum drbd_fencing_p fp;
-	enum drbd_req_event what = nothing;
-	union drbd_state nsm = (union drbd_state){ .i = -1 };
-
-	if (os.conn != C_CONNECTED && ns.conn == C_CONNECTED) {
-		drbd_clear_flag(mdev, CRASHED_PRIMARY);
-		if (mdev->p_uuid)
-			mdev->p_uuid[UI_FLAGS] &= ~((u64)2);
-	}
-
-	fp = FP_DONT_CARE;
-	if (get_ldev(mdev)) {
-		fp = mdev->ldev->dc.fencing;
-		put_ldev(mdev);
-	}
-
-	/* Inform userspace about the change... */
-	drbd_bcast_state(mdev, ns);
-
-	if (!(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE) &&
-	    (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE))
-		drbd_khelper(mdev, "pri-on-incon-degr");
-
-	/* Here we have the actions that are performed after a
-	   state change. This function might sleep */
-
-	if (os.disk <= D_NEGOTIATING && ns.disk > D_NEGOTIATING)
-		mod_timer(&mdev->request_timer, jiffies + HZ);
-
-	nsm.i = -1;
-	if (ns.susp_nod) {
-		if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
-			what = resend;
-
-		if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
-		    ns.disk > D_NEGOTIATING)
-			what = restart_frozen_disk_io;
-
-		if (what != nothing)
-			nsm.susp_nod = 0;
-	}
-
-	if (ns.susp_fen) {
-		/* case1: The outdate peer handler is successful: */
-		if (os.pdsk > D_OUTDATED  && ns.pdsk <= D_OUTDATED) {
-			if (drbd_test_flag(mdev, NEW_CUR_UUID)) {
-				drbd_uuid_new_current(mdev);
-				drbd_clear_flag(mdev, NEW_CUR_UUID);
-			}
-			spin_lock_irq(&mdev->req_lock);
-			_tl_clear(mdev);
-			_drbd_set_state(_NS(mdev, susp_fen, 0), CS_VERBOSE, NULL);
-			spin_unlock_irq(&mdev->req_lock);
-		}
-		/* case2: The connection was established again: */
-		if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED) {
-			drbd_clear_flag(mdev, NEW_CUR_UUID);
-			what = resend;
-			nsm.susp_fen = 0;
-		}
-	}
-
-	if (what != nothing) {
-		spin_lock_irq(&mdev->req_lock);
-		_tl_restart(mdev, what);
-		nsm.i &= mdev->state.i;
-		_drbd_set_state(mdev, nsm, CS_VERBOSE, NULL);
-		spin_unlock_irq(&mdev->req_lock);
-	}
-
-	/* Became sync source.  With protocol >= 96, we still need to send out
-	 * the sync uuid now. Need to do that before any drbd_send_state, or
-	 * the other side may go "paused sync" before receiving the sync uuids,
-	 * which is unexpected. */
-	if ((os.conn != C_SYNC_SOURCE && os.conn != C_PAUSED_SYNC_S) &&
-	    (ns.conn == C_SYNC_SOURCE || ns.conn == C_PAUSED_SYNC_S) &&
-	    mdev->agreed_pro_version >= 96 && get_ldev(mdev)) {
-		drbd_gen_and_send_sync_uuid(mdev);
-		put_ldev(mdev);
-	}
-
-	/* Do not change the order of the if above and the two below... */
-	if (os.pdsk == D_DISKLESS && ns.pdsk > D_DISKLESS) {      /* attach on the peer */
-		/* we probably will start a resync soon.
-		 * make sure those things are properly reset. */
-		mdev->rs_total = 0;
-		mdev->rs_failed = 0;
-		atomic_set(&mdev->rs_pending_cnt, 0);
-		drbd_rs_cancel_all(mdev);
-
-		drbd_send_uuids(mdev);
-		drbd_send_state(mdev, ns);
-	}
-	/* No point in queuing send_bitmap if we don't have a connection
-	 * anymore, so check also the _current_ state, not only the new state
-	 * at the time this work was queued. */
-	if (os.conn != C_WF_BITMAP_S && ns.conn == C_WF_BITMAP_S &&
-	    mdev->state.conn == C_WF_BITMAP_S)
-		drbd_queue_bitmap_io(mdev, &drbd_send_bitmap, NULL,
-				"send_bitmap (WFBitMapS)",
-				BM_LOCKED_TEST_ALLOWED);
-
-	/* Lost contact to peer's copy of the data */
-	if ((os.pdsk >= D_INCONSISTENT &&
-	     os.pdsk != D_UNKNOWN &&
-	     os.pdsk != D_OUTDATED)
-	&&  (ns.pdsk < D_INCONSISTENT ||
-	     ns.pdsk == D_UNKNOWN ||
-	     ns.pdsk == D_OUTDATED)) {
-		if (get_ldev(mdev)) {
-			if ((ns.role == R_PRIMARY || ns.peer == R_PRIMARY) &&
-			    mdev->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
-				if (is_susp(mdev->state)) {
-					drbd_set_flag(mdev, NEW_CUR_UUID);
-				} else {
-					drbd_uuid_new_current(mdev);
-					drbd_send_uuids(mdev);
-				}
-			}
-			put_ldev(mdev);
-		}
-	}
-
-	if (ns.pdsk < D_INCONSISTENT && get_ldev(mdev)) {
-		if (os.peer == R_SECONDARY && ns.peer == R_PRIMARY &&
-		    mdev->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
-			drbd_uuid_new_current(mdev);
-			drbd_send_uuids(mdev);
-		}
-		/* D_DISKLESS Peer becomes secondary */
-		if (os.peer == R_PRIMARY && ns.peer == R_SECONDARY)
-			/* We may still be Primary ourselves.
-			 * No harm done if the bitmap still changes,
-			 * redirtied pages will follow later. */
-			drbd_bitmap_io_from_worker(mdev, &drbd_bm_write,
-				"demote diskless peer", BM_LOCKED_SET_ALLOWED);
-		put_ldev(mdev);
-	}
-
-	/* Write out all changed bits on demote.
-	 * Though, no need to da that just yet
-	 * if there is a resync going on still */
-	if (os.role == R_PRIMARY && ns.role == R_SECONDARY &&
-		mdev->state.conn <= C_CONNECTED && get_ldev(mdev)) {
-		/* No changes to the bitmap expected this time, so assert that,
-		 * even though no harm was done if it did change. */
-		drbd_bitmap_io_from_worker(mdev, &drbd_bm_write,
-				"demote", BM_LOCKED_TEST_ALLOWED);
-		put_ldev(mdev);
-	}
-
-	/* Last part of the attaching process ... */
-	if (ns.conn >= C_CONNECTED &&
-	    os.disk == D_ATTACHING && ns.disk == D_NEGOTIATING) {
-		drbd_send_sizes(mdev, 0, 0);  /* to start sync... */
-		drbd_send_uuids(mdev);
-		drbd_send_state(mdev, ns);
-	}
-
-	/* We want to pause/continue resync, tell peer. */
-	if (ns.conn >= C_CONNECTED &&
-	     ((os.aftr_isp != ns.aftr_isp) ||
-	      (os.user_isp != ns.user_isp)))
-		drbd_send_state(mdev, ns);
-
-	/* 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 == C_WF_REPORT_PARAMS && ns.conn >= C_CONNECTED)
-		drbd_send_state(mdev, ns);
-
-	if (os.conn != C_AHEAD && ns.conn == C_AHEAD)
-		drbd_send_state(mdev, ns);
-
-	/* We are in the progress to start a full sync... */
-	if ((os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
-	    (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S))
-		/* no other bitmap changes expected during this phase */
-		drbd_queue_bitmap_io(mdev,
-			&drbd_bmio_set_n_write, &abw_start_sync,
-			"set_n_write from StartingSync", BM_LOCKED_TEST_ALLOWED);
-
-	/* We are invalidating our self... */
-	if (os.conn < C_CONNECTED && ns.conn < C_CONNECTED &&
-	    os.disk > D_INCONSISTENT && ns.disk == D_INCONSISTENT)
-		/* other bitmap operation expected during this phase */
-		drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, NULL,
-			"set_n_write from invalidate", BM_LOCKED_MASK);
-
-	/* first half of local IO error, failure to attach,
-	 * or administrative detach */
-	if (os.disk != D_FAILED && ns.disk == D_FAILED) {
-		/* corresponding get_ldev was in __drbd_set_state, to serialize
-		 * our cleanup here with the transition to D_DISKLESS.
-		 * But it is still not safe to dreference ldev here, we may end
-		 * up here from a failed attach, before ldev was even set.  */
-		if (mdev->ldev) {
-			enum drbd_io_error_p eh = mdev->ldev->dc.on_io_error;
-
-			/* In some setups, this handler triggers a suicide,
-			 * basically mapping IO error to node failure, to
-			 * reduce the number of different failure scenarios.
-			 *
-			 * This handler intentionally runs before we abort IO,
-			 * notify the peer, or try to update our meta data. */
-			if (eh == EP_CALL_HELPER && drbd_test_flag(mdev, WAS_IO_ERROR))
-				drbd_khelper(mdev, "local-io-error");
-
-			/* Immediately allow completion of all application IO,
-			 * that waits for completion from the local disk,
-			 * if this was a force-detach due to disk_timeout
-			 * or administrator request (drbdsetup detach --force).
-			 * Do NOT abort otherwise.
-			 * Aborting local requests may cause serious problems,
-			 * if requests are completed to upper layers already,
-			 * and then later the already submitted local bio completes.
-			 * This can cause DMA into former bio pages that meanwhile
-			 * have been re-used for other things.
-			 * So aborting local requests may cause crashes,
-			 * or even worse, silent data corruption.
-			 */
-			if (drbd_test_flag(mdev, FORCE_DETACH))
-				tl_abort_disk_io(mdev);
-
-			/* current state still has to be D_FAILED,
-			 * there is only one way out: to D_DISKLESS,
-			 * and that may only happen after our put_ldev below. */
-			if (mdev->state.disk != D_FAILED)
-				dev_err(DEV,
-					"ASSERT FAILED: disk is %s during detach\n",
-					drbd_disk_str(mdev->state.disk));
-
-			if (ns.conn >= C_CONNECTED)
-				drbd_send_state(mdev, ns);
-
-			drbd_rs_cancel_all(mdev);
-
-			/* In case we want to get something to stable storage still,
-			 * this may be the last chance.
-			 * Following put_ldev may transition to D_DISKLESS. */
-			drbd_md_sync(mdev);
-		}
-		put_ldev(mdev);
-	}
-
-        /* second half of local IO error, failure to attach,
-         * or administrative detach,
-         * after local_cnt references have reached zero again */
-        if (os.disk != D_DISKLESS && ns.disk == D_DISKLESS) {
-                /* We must still be diskless,
-                 * re-attach has to be serialized with this! */
-                if (mdev->state.disk != D_DISKLESS)
-                        dev_err(DEV,
-                                "ASSERT FAILED: disk is %s while going diskless\n",
-                                drbd_disk_str(mdev->state.disk));
-
-		if (ns.conn >= C_CONNECTED)
-			drbd_send_state(mdev, ns);
-
-		/* corresponding get_ldev in __drbd_set_state
-		 * this may finally trigger drbd_ldev_destroy. */
-		put_ldev(mdev);
-	}
-
-	/* Notify peer that I had a local IO error, and did not detached.. */
-	if (os.disk == D_UP_TO_DATE && ns.disk == D_INCONSISTENT && ns.conn >= C_CONNECTED)
-		drbd_send_state(mdev, ns);
-
-	/* Disks got bigger while they were detached */
-	if (ns.disk > D_NEGOTIATING && ns.pdsk > D_NEGOTIATING &&
-	    drbd_test_and_clear_flag(mdev, RESYNC_AFTER_NEG)) {
-		if (ns.conn == C_CONNECTED)
-			resync_after_online_grow(mdev);
-	}
-
-	/* A resync finished or aborted, wake paused devices... */
-	if ((os.conn > C_CONNECTED && ns.conn <= C_CONNECTED) ||
-	    (os.peer_isp && !ns.peer_isp) ||
-	    (os.user_isp && !ns.user_isp))
-		resume_next_sg(mdev);
-
-	/* sync target done with resync.  Explicitly notify peer, even though
-	 * it should (at least for non-empty resyncs) already know itself. */
-	if (os.disk < D_UP_TO_DATE && os.conn >= C_SYNC_SOURCE && ns.conn == C_CONNECTED)
-		drbd_send_state(mdev, ns);
-
-	/* Verify finished, or reached stop sector.  Peer did not know about
-	 * the stop sector, and we may even have changed the stop sector during
-	 * verify to interrupt/stop early.  Send the new state. */
-	if (os.conn == C_VERIFY_S && ns.conn == C_CONNECTED
-	&& mdev->agreed_pro_version >= 97)
-		drbd_send_state(mdev, ns);
-
-	/* Wake up role changes, that were delayed because of connection establishing */
-	if (os.conn == C_WF_REPORT_PARAMS && ns.conn != C_WF_REPORT_PARAMS) {
-		drbd_clear_flag(mdev, STATE_SENT);
-		wake_up(&mdev->state_wait);
-	}
-
-	/* This triggers bitmap writeout of potentially still unwritten pages
-	 * if the resync finished cleanly, or aborted because of peer disk
-	 * failure, or because of connection loss.
-	 * For resync aborted because of local disk failure, we cannot do
-	 * any bitmap writeout anymore.
-	 * No harm done if some bits change during this phase.
-	 */
-	if (os.conn > C_CONNECTED && ns.conn <= C_CONNECTED && get_ldev(mdev)) {
-		drbd_queue_bitmap_io(mdev, &drbd_bm_write_copy_pages, NULL,
-			"write from resync_finished", BM_LOCKED_CHANGE_ALLOWED);
-		put_ldev(mdev);
-	}
-
-	/* free tl_hash if we Got thawed and are C_STANDALONE */
-	if (ns.conn == C_STANDALONE && !is_susp(ns) && mdev->tl_hash)
-		drbd_free_tl_hash(mdev);
-
-	/* Upon network connection, we need to start the receiver */
-	if (os.conn == C_STANDALONE && ns.conn == C_UNCONNECTED)
-		drbd_thread_start(&mdev->receiver);
-
-	/* Terminate worker thread if we are unconfigured - it will be
-	   restarted as needed... */
-	if (ns.disk == D_DISKLESS &&
-	    ns.conn == C_STANDALONE &&
-	    ns.role == R_SECONDARY) {
-		if (os.aftr_isp != ns.aftr_isp)
-			resume_next_sg(mdev);
-		/* set in __drbd_set_state, unless CONFIG_PENDING was set */
-		if (drbd_test_flag(mdev, DEVICE_DYING))
-			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;
+	struct drbd_tconn *tconn = thi->tconn;
 	unsigned long flags;
 	int retval;
 
+	snprintf(current->comm, sizeof(current->comm), "drbd_%c_%s",
+		 thi->name[0], thi->tconn->name);
+
 restart:
 	retval = thi->function(thi);
 
 	spin_lock_irqsave(&thi->t_lock, flags);
 
-	/* if the receiver has been "Exiting", the last thing it did
+	/* 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 C_UNCONNECTED,
 	 * and receiver thread will be "started".
-	 * drbd_thread_start needs to set "Restarting" in that case.
+	 * drbd_thread_start needs to set "RESTARTING" in that case.
 	 * t_state check and assignment 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.
+	 * 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) {
-		dev_info(DEV, "Restarting %s\n", current->comm);
-		thi->t_state = Running;
+	if (thi->t_state == RESTARTING) {
+		conn_info(tconn, "Restarting %s thread\n", thi->name);
+		thi->t_state = RUNNING;
 		spin_unlock_irqrestore(&thi->t_lock, flags);
 		goto restart;
 	}
 
 	thi->task = NULL;
-	thi->t_state = None;
+	thi->t_state = NONE;
 	smp_mb();
-	complete(&thi->stop);
+	complete_all(&thi->stop);
 	spin_unlock_irqrestore(&thi->t_lock, flags);
 
-	dev_info(DEV, "Terminating %s\n", current->comm);
+	conn_info(tconn, "Terminating %s\n", current->comm);
 
 	/* Release mod reference taken when thread was started */
+
+	kref_put(&tconn->kref, &conn_destroy);
 	module_put(THIS_MODULE);
 	return retval;
 }
 
-static void drbd_thread_init(struct drbd_conf *mdev, struct drbd_thread *thi,
-		      int (*func) (struct drbd_thread *))
+static void drbd_thread_init(struct drbd_tconn *tconn, struct drbd_thread *thi,
+			     int (*func) (struct drbd_thread *), char *name)
 {
 	spin_lock_init(&thi->t_lock);
 	thi->task    = NULL;
-	thi->t_state = None;
+	thi->t_state = NONE;
 	thi->function = func;
-	thi->mdev = mdev;
+	thi->tconn = tconn;
+	strncpy(thi->name, name, ARRAY_SIZE(thi->name));
 }
 
 int drbd_thread_start(struct drbd_thread *thi)
 {
-	struct drbd_conf *mdev = thi->mdev;
+	struct drbd_tconn *tconn = thi->tconn;
 	struct task_struct *nt;
 	unsigned long flags;
 
-	const char *me =
-		thi == &mdev->receiver ? "receiver" :
-		thi == &mdev->asender  ? "asender"  :
-		thi == &mdev->worker   ? "worker"   : "NONSENSE";
-
 	/* is used from state engine doing drbd_thread_stop_nowait,
 	 * while holding the req lock irqsave */
 	spin_lock_irqsave(&thi->t_lock, flags);
 
 	switch (thi->t_state) {
-	case None:
-		dev_info(DEV, "Starting %s thread (from %s [%d])\n",
-				me, current->comm, current->pid);
+	case NONE:
+		conn_info(tconn, "Starting %s thread (from %s [%d])\n",
+			 thi->name, current->comm, current->pid);
 
 		/* Get ref on module for thread - this is released when thread exits */
 		if (!try_module_get(THIS_MODULE)) {
-			dev_err(DEV, "Failed to get module reference in drbd_thread_start\n");
+			conn_err(tconn, "Failed to get module reference in drbd_thread_start\n");
 			spin_unlock_irqrestore(&thi->t_lock, flags);
 			return false;
 		}
 
+		kref_get(&thi->tconn->kref);
+
 		init_completion(&thi->stop);
-		D_ASSERT(thi->task == NULL);
 		thi->reset_cpu_mask = 1;
-		thi->t_state = Running;
+		thi->t_state = RUNNING;
 		spin_unlock_irqrestore(&thi->t_lock, flags);
 		flush_signals(current); /* otherw. may get -ERESTARTNOINTR */
 
 		nt = kthread_create(drbd_thread_setup, (void *) thi,
-				    "drbd%d_%s", mdev_to_minor(mdev), me);
+				    "drbd_%c_%s", thi->name[0], thi->tconn->name);
 
 		if (IS_ERR(nt)) {
-			dev_err(DEV, "Couldn't start thread\n");
+			conn_err(tconn, "Couldn't start thread\n");
 
+			kref_put(&tconn->kref, &conn_destroy);
 			module_put(THIS_MODULE);
 			return false;
 		}
 		spin_lock_irqsave(&thi->t_lock, flags);
 		thi->task = nt;
-		thi->t_state = Running;
+		thi->t_state = RUNNING;
 		spin_unlock_irqrestore(&thi->t_lock, flags);
 		wake_up_process(nt);
 		break;
-	case Exiting:
-		thi->t_state = Restarting;
-		dev_info(DEV, "Restarting %s thread (from %s [%d])\n",
-				me, current->comm, current->pid);
+	case EXITING:
+		thi->t_state = RESTARTING;
+		conn_info(tconn, "Restarting %s thread (from %s [%d])\n",
+				thi->name, current->comm, current->pid);
 		/* fall through */
-	case Running:
-	case Restarting:
+	case RUNNING:
+	case RESTARTING:
 	default:
 		spin_unlock_irqrestore(&thi->t_lock, flags);
 		break;
@@ -1882,12 +447,12 @@
 {
 	unsigned long flags;
 
-	enum drbd_thread_state ns = restart ? Restarting : Exiting;
+	enum drbd_thread_state ns = restart ? RESTARTING : EXITING;
 
 	/* may be called from state engine, holding the req lock irqsave */
 	spin_lock_irqsave(&thi->t_lock, flags);
 
-	if (thi->t_state == None) {
+	if (thi->t_state == NONE) {
 		spin_unlock_irqrestore(&thi->t_lock, flags);
 		if (restart)
 			drbd_thread_start(thi);
@@ -1905,7 +470,6 @@
 		init_completion(&thi->stop);
 		if (thi->task != current)
 			force_sig(DRBD_SIGKILL, thi->task);
-
 	}
 
 	spin_unlock_irqrestore(&thi->t_lock, flags);
@@ -1914,6 +478,35 @@
 		wait_for_completion(&thi->stop);
 }
 
+static struct drbd_thread *drbd_task_to_thread(struct drbd_tconn *tconn, struct task_struct *task)
+{
+	struct drbd_thread *thi =
+		task == tconn->receiver.task ? &tconn->receiver :
+		task == tconn->asender.task  ? &tconn->asender :
+		task == tconn->worker.task   ? &tconn->worker : NULL;
+
+	return thi;
+}
+
+char *drbd_task_to_thread_name(struct drbd_tconn *tconn, struct task_struct *task)
+{
+	struct drbd_thread *thi = drbd_task_to_thread(tconn, task);
+	return thi ? thi->name : task->comm;
+}
+
+int conn_lowest_minor(struct drbd_tconn *tconn)
+{
+	struct drbd_conf *mdev;
+	int vnr = 0, m;
+
+	rcu_read_lock();
+	mdev = idr_get_next(&tconn->volumes, &vnr);
+	m = mdev ? mdev_to_minor(mdev) : -1;
+	rcu_read_unlock();
+
+	return m;
+}
+
 #ifdef CONFIG_SMP
 /**
  * drbd_calc_cpu_mask() - Generate CPU masks, spread over all CPUs
@@ -1922,240 +515,345 @@
  * Forces all threads of a device onto the same CPU. This is beneficial for
  * DRBD's performance. May be overwritten by user's configuration.
  */
-void drbd_calc_cpu_mask(struct drbd_conf *mdev)
+void drbd_calc_cpu_mask(struct drbd_tconn *tconn)
 {
 	int ord, cpu;
 
 	/* user override. */
-	if (cpumask_weight(mdev->cpu_mask))
+	if (cpumask_weight(tconn->cpu_mask))
 		return;
 
-	ord = mdev_to_minor(mdev) % cpumask_weight(cpu_online_mask);
+	ord = conn_lowest_minor(tconn) % cpumask_weight(cpu_online_mask);
 	for_each_online_cpu(cpu) {
 		if (ord-- == 0) {
-			cpumask_set_cpu(cpu, mdev->cpu_mask);
+			cpumask_set_cpu(cpu, tconn->cpu_mask);
 			return;
 		}
 	}
 	/* should not be reached */
-	cpumask_setall(mdev->cpu_mask);
+	cpumask_setall(tconn->cpu_mask);
 }
 
 /**
  * drbd_thread_current_set_cpu() - modifies the cpu mask of the _current_ thread
  * @mdev:	DRBD device.
+ * @thi:	drbd_thread object
  *
  * 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)
+void drbd_thread_current_set_cpu(struct drbd_thread *thi)
 {
 	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;
-	set_cpus_allowed_ptr(p, mdev->cpu_mask);
+	set_cpus_allowed_ptr(p, thi->tconn->cpu_mask);
 }
 #endif
 
-/* the appropriate socket mutex must be held already */
-int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,
-			  enum drbd_packets cmd, struct p_header80 *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 p_header80));
-
-	sent = drbd_send(mdev, sock, h, size, msg_flags);
-
-	ok = (sent == size);
-	if (!ok && !signal_pending(current))
-		dev_warn(DEV, "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.
+/**
+ * drbd_header_size  -  size of a packet header
+ *
+ * The header size is a multiple of 8, so any payload following the header is
+ * word aligned on 64-bit architectures.  (The bitmap send and receive code
+ * relies on this.)
  */
-int drbd_send_cmd(struct drbd_conf *mdev, int use_data_socket,
-		  enum drbd_packets cmd, struct p_header80 *h, size_t size)
+unsigned int drbd_header_size(struct drbd_tconn *tconn)
 {
-	int ok = 0;
-	struct socket *sock;
-
-	if (use_data_socket) {
-		mutex_lock(&mdev->data.mutex);
-		sock = mdev->data.socket;
+	if (tconn->agreed_pro_version >= 100) {
+		BUILD_BUG_ON(!IS_ALIGNED(sizeof(struct p_header100), 8));
+		return sizeof(struct p_header100);
 	} else {
-		mutex_lock(&mdev->meta.mutex);
-		sock = mdev->meta.socket;
+		BUILD_BUG_ON(sizeof(struct p_header80) !=
+			     sizeof(struct p_header95));
+		BUILD_BUG_ON(!IS_ALIGNED(sizeof(struct p_header80), 8));
+		return sizeof(struct p_header80);
 	}
+}
 
-	/* 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);
+static unsigned int prepare_header80(struct p_header80 *h, enum drbd_packet cmd, int size)
+{
+	h->magic   = cpu_to_be32(DRBD_MAGIC);
+	h->command = cpu_to_be16(cmd);
+	h->length  = cpu_to_be16(size);
+	return sizeof(struct p_header80);
+}
 
-	if (use_data_socket)
-		mutex_unlock(&mdev->data.mutex);
+static unsigned int prepare_header95(struct p_header95 *h, enum drbd_packet cmd, int size)
+{
+	h->magic   = cpu_to_be16(DRBD_MAGIC_BIG);
+	h->command = cpu_to_be16(cmd);
+	h->length = cpu_to_be32(size);
+	return sizeof(struct p_header95);
+}
+
+static unsigned int prepare_header100(struct p_header100 *h, enum drbd_packet cmd,
+				      int size, int vnr)
+{
+	h->magic = cpu_to_be32(DRBD_MAGIC_100);
+	h->volume = cpu_to_be16(vnr);
+	h->command = cpu_to_be16(cmd);
+	h->length = cpu_to_be32(size);
+	h->pad = 0;
+	return sizeof(struct p_header100);
+}
+
+static unsigned int prepare_header(struct drbd_tconn *tconn, int vnr,
+				   void *buffer, enum drbd_packet cmd, int size)
+{
+	if (tconn->agreed_pro_version >= 100)
+		return prepare_header100(buffer, cmd, size, vnr);
+	else if (tconn->agreed_pro_version >= 95 &&
+		 size > DRBD_MAX_SIZE_H80_PACKET)
+		return prepare_header95(buffer, cmd, size);
 	else
-		mutex_unlock(&mdev->meta.mutex);
-	return ok;
+		return prepare_header80(buffer, cmd, size);
 }
 
-int drbd_send_cmd2(struct drbd_conf *mdev, enum drbd_packets cmd, char *data,
-		   size_t size)
+static void *__conn_prepare_command(struct drbd_tconn *tconn,
+				    struct drbd_socket *sock)
 {
-	struct p_header80 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;
-
-	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;
+	if (!sock->socket)
+		return NULL;
+	return sock->sbuf + drbd_header_size(tconn);
 }
 
-int drbd_send_sync_param(struct drbd_conf *mdev, struct syncer_conf *sc)
+void *conn_prepare_command(struct drbd_tconn *tconn, struct drbd_socket *sock)
 {
+	void *p;
+
+	mutex_lock(&sock->mutex);
+	p = __conn_prepare_command(tconn, sock);
+	if (!p)
+		mutex_unlock(&sock->mutex);
+
+	return p;
+}
+
+void *drbd_prepare_command(struct drbd_conf *mdev, struct drbd_socket *sock)
+{
+	return conn_prepare_command(mdev->tconn, sock);
+}
+
+static int __send_command(struct drbd_tconn *tconn, int vnr,
+			  struct drbd_socket *sock, enum drbd_packet cmd,
+			  unsigned int header_size, void *data,
+			  unsigned int size)
+{
+	int msg_flags;
+	int err;
+
+	/*
+	 * Called with @data == NULL and the size of the data blocks in @size
+	 * for commands that send data blocks.  For those commands, omit the
+	 * MSG_MORE flag: this will increase the likelihood that data blocks
+	 * which are page aligned on the sender will end up page aligned on the
+	 * receiver.
+	 */
+	msg_flags = data ? MSG_MORE : 0;
+
+	header_size += prepare_header(tconn, vnr, sock->sbuf, cmd,
+				      header_size + size);
+	err = drbd_send_all(tconn, sock->socket, sock->sbuf, header_size,
+			    msg_flags);
+	if (data && !err)
+		err = drbd_send_all(tconn, sock->socket, data, size, 0);
+	return err;
+}
+
+static int __conn_send_command(struct drbd_tconn *tconn, struct drbd_socket *sock,
+			       enum drbd_packet cmd, unsigned int header_size,
+			       void *data, unsigned int size)
+{
+	return __send_command(tconn, 0, sock, cmd, header_size, data, size);
+}
+
+int conn_send_command(struct drbd_tconn *tconn, struct drbd_socket *sock,
+		      enum drbd_packet cmd, unsigned int header_size,
+		      void *data, unsigned int size)
+{
+	int err;
+
+	err = __conn_send_command(tconn, sock, cmd, header_size, data, size);
+	mutex_unlock(&sock->mutex);
+	return err;
+}
+
+int drbd_send_command(struct drbd_conf *mdev, struct drbd_socket *sock,
+		      enum drbd_packet cmd, unsigned int header_size,
+		      void *data, unsigned int size)
+{
+	int err;
+
+	err = __send_command(mdev->tconn, mdev->vnr, sock, cmd, header_size,
+			     data, size);
+	mutex_unlock(&sock->mutex);
+	return err;
+}
+
+int drbd_send_ping(struct drbd_tconn *tconn)
+{
+	struct drbd_socket *sock;
+
+	sock = &tconn->meta;
+	if (!conn_prepare_command(tconn, sock))
+		return -EIO;
+	return conn_send_command(tconn, sock, P_PING, 0, NULL, 0);
+}
+
+int drbd_send_ping_ack(struct drbd_tconn *tconn)
+{
+	struct drbd_socket *sock;
+
+	sock = &tconn->meta;
+	if (!conn_prepare_command(tconn, sock))
+		return -EIO;
+	return conn_send_command(tconn, sock, P_PING_ACK, 0, NULL, 0);
+}
+
+int drbd_send_sync_param(struct drbd_conf *mdev)
+{
+	struct drbd_socket *sock;
 	struct p_rs_param_95 *p;
-	struct socket *sock;
-	int size, rv;
-	const int apv = mdev->agreed_pro_version;
+	int size;
+	const int apv = mdev->tconn->agreed_pro_version;
+	enum drbd_packet cmd;
+	struct net_conf *nc;
+	struct disk_conf *dc;
+
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+
+	rcu_read_lock();
+	nc = rcu_dereference(mdev->tconn->net_conf);
 
 	size = apv <= 87 ? sizeof(struct p_rs_param)
 		: apv == 88 ? sizeof(struct p_rs_param)
-			+ strlen(mdev->sync_conf.verify_alg) + 1
+			+ strlen(nc->verify_alg) + 1
 		: apv <= 94 ? sizeof(struct p_rs_param_89)
 		: /* apv >= 95 */ sizeof(struct p_rs_param_95);
 
-	/* 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;
+	cmd = apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM;
 
-	if (likely(sock != NULL)) {
-		enum drbd_packets cmd = apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM;
+	/* initialize verify_alg and csums_alg */
+	memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
 
-		p = &mdev->data.sbuf.rs_param_95;
+	if (get_ldev(mdev)) {
+		dc = rcu_dereference(mdev->ldev->disk_conf);
+		p->resync_rate = cpu_to_be32(dc->resync_rate);
+		p->c_plan_ahead = cpu_to_be32(dc->c_plan_ahead);
+		p->c_delay_target = cpu_to_be32(dc->c_delay_target);
+		p->c_fill_target = cpu_to_be32(dc->c_fill_target);
+		p->c_max_rate = cpu_to_be32(dc->c_max_rate);
+		put_ldev(mdev);
+	} else {
+		p->resync_rate = cpu_to_be32(DRBD_RESYNC_RATE_DEF);
+		p->c_plan_ahead = cpu_to_be32(DRBD_C_PLAN_AHEAD_DEF);
+		p->c_delay_target = cpu_to_be32(DRBD_C_DELAY_TARGET_DEF);
+		p->c_fill_target = cpu_to_be32(DRBD_C_FILL_TARGET_DEF);
+		p->c_max_rate = cpu_to_be32(DRBD_C_MAX_RATE_DEF);
+	}
 
-		/* initialize verify_alg and csums_alg */
-		memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
+	if (apv >= 88)
+		strcpy(p->verify_alg, nc->verify_alg);
+	if (apv >= 89)
+		strcpy(p->csums_alg, nc->csums_alg);
+	rcu_read_unlock();
 
-		p->rate = cpu_to_be32(sc->rate);
-		p->c_plan_ahead = cpu_to_be32(sc->c_plan_ahead);
-		p->c_delay_target = cpu_to_be32(sc->c_delay_target);
-		p->c_fill_target = cpu_to_be32(sc->c_fill_target);
-		p->c_max_rate = cpu_to_be32(sc->c_max_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;
+	return drbd_send_command(mdev, sock, cmd, size, NULL, 0);
 }
 
-int drbd_send_protocol(struct drbd_conf *mdev)
+int __drbd_send_protocol(struct drbd_tconn *tconn, enum drbd_packet cmd)
 {
+	struct drbd_socket *sock;
 	struct p_protocol *p;
-	int size, cf, rv;
+	struct net_conf *nc;
+	int size, cf;
 
-	size = sizeof(struct p_protocol);
+	sock = &tconn->data;
+	p = __conn_prepare_command(tconn, sock);
+	if (!p)
+		return -EIO;
 
-	if (mdev->agreed_pro_version >= 87)
-		size += strlen(mdev->net_conf->integrity_alg) + 1;
+	rcu_read_lock();
+	nc = rcu_dereference(tconn->net_conf);
 
-	/* we must not recurse into our own queue,
-	 * as that is blocked during handshake */
-	p = kmalloc(size, GFP_NOIO);
-	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->two_primaries = cpu_to_be32(mdev->net_conf->two_primaries);
-
-	cf = 0;
-	if (mdev->net_conf->want_lose)
-		cf |= CF_WANT_LOSE;
-	if (mdev->net_conf->dry_run) {
-		if (mdev->agreed_pro_version >= 92)
-			cf |= CF_DRY_RUN;
-		else {
-			dev_err(DEV, "--dry-run is not supported by peer");
-			kfree(p);
-			return -1;
-		}
+	if (nc->tentative && tconn->agreed_pro_version < 92) {
+		rcu_read_unlock();
+		mutex_unlock(&sock->mutex);
+		conn_err(tconn, "--dry-run is not supported by peer");
+		return -EOPNOTSUPP;
 	}
+
+	size = sizeof(*p);
+	if (tconn->agreed_pro_version >= 87)
+		size += strlen(nc->integrity_alg) + 1;
+
+	p->protocol      = cpu_to_be32(nc->wire_protocol);
+	p->after_sb_0p   = cpu_to_be32(nc->after_sb_0p);
+	p->after_sb_1p   = cpu_to_be32(nc->after_sb_1p);
+	p->after_sb_2p   = cpu_to_be32(nc->after_sb_2p);
+	p->two_primaries = cpu_to_be32(nc->two_primaries);
+	cf = 0;
+	if (nc->discard_my_data)
+		cf |= CF_DISCARD_MY_DATA;
+	if (nc->tentative)
+		cf |= CF_DRY_RUN;
 	p->conn_flags    = cpu_to_be32(cf);
 
-	if (mdev->agreed_pro_version >= 87)
-		strcpy(p->integrity_alg, mdev->net_conf->integrity_alg);
+	if (tconn->agreed_pro_version >= 87)
+		strcpy(p->integrity_alg, nc->integrity_alg);
+	rcu_read_unlock();
 
-	rv = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_PROTOCOL,
-			   (struct p_header80 *)p, size);
-	kfree(p);
-	return rv;
+	return __conn_send_command(tconn, sock, cmd, size, NULL, 0);
+}
+
+int drbd_send_protocol(struct drbd_tconn *tconn)
+{
+	int err;
+
+	mutex_lock(&tconn->data.mutex);
+	err = __drbd_send_protocol(tconn, P_PROTOCOL);
+	mutex_unlock(&tconn->data.mutex);
+
+	return err;
 }
 
 int _drbd_send_uuids(struct drbd_conf *mdev, u64 uuid_flags)
 {
-	struct p_uuids p;
+	struct drbd_socket *sock;
+	struct p_uuids *p;
 	int i;
 
 	if (!get_ldev_if_state(mdev, D_NEGOTIATING))
-		return 1;
+		return 0;
 
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p) {
+		put_ldev(mdev);
+		return -EIO;
+	}
 	spin_lock_irq(&mdev->ldev->md.uuid_lock);
 	for (i = UI_CURRENT; i < UI_SIZE; i++)
-		p.uuid[i] = mdev->ldev ? cpu_to_be64(mdev->ldev->md.uuid[i]) : 0;
+		p->uuid[i] = mdev->ldev ? cpu_to_be64(mdev->ldev->md.uuid[i]) : 0;
 	spin_unlock_irq(&mdev->ldev->md.uuid_lock);
 
 	mdev->comm_bm_set = drbd_bm_total_weight(mdev);
-	p.uuid[UI_SIZE] = cpu_to_be64(mdev->comm_bm_set);
-	uuid_flags |= mdev->net_conf->want_lose ? 1 : 0;
-	uuid_flags |= drbd_test_flag(mdev, CRASHED_PRIMARY) ? 2 : 0;
+	p->uuid[UI_SIZE] = cpu_to_be64(mdev->comm_bm_set);
+	rcu_read_lock();
+	uuid_flags |= rcu_dereference(mdev->tconn->net_conf)->discard_my_data ? 1 : 0;
+	rcu_read_unlock();
+	uuid_flags |= test_bit(CRASHED_PRIMARY, &mdev->flags) ? 2 : 0;
 	uuid_flags |= mdev->new_state_tmp.disk == D_INCONSISTENT ? 4 : 0;
-	p.uuid[UI_FLAGS] = cpu_to_be64(uuid_flags);
+	p->uuid[UI_FLAGS] = cpu_to_be64(uuid_flags);
 
 	put_ldev(mdev);
-
-	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_UUIDS,
-			     (struct p_header80 *)&p, sizeof(p));
+	return drbd_send_command(mdev, sock, P_UUIDS, sizeof(*p), NULL, 0);
 }
 
 int drbd_send_uuids(struct drbd_conf *mdev)
@@ -2186,9 +884,10 @@
 	}
 }
 
-int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
+void drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
 {
-	struct p_rs_uuid p;
+	struct drbd_socket *sock;
+	struct p_rs_uuid *p;
 	u64 uuid;
 
 	D_ASSERT(mdev->state.disk == D_UP_TO_DATE);
@@ -2201,24 +900,29 @@
 	drbd_uuid_set(mdev, UI_BITMAP, uuid);
 	drbd_print_uuids(mdev, "updated sync UUID");
 	drbd_md_sync(mdev);
-	p.uuid = cpu_to_be64(uuid);
 
-	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_SYNC_UUID,
-			     (struct p_header80 *)&p, sizeof(p));
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (p) {
+		p->uuid = cpu_to_be64(uuid);
+		drbd_send_command(mdev, sock, P_SYNC_UUID, sizeof(*p), NULL, 0);
+	}
 }
 
 int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags flags)
 {
-	struct p_sizes p;
+	struct drbd_socket *sock;
+	struct p_sizes *p;
 	sector_t d_size, u_size;
 	int q_order_type;
 	unsigned int max_bio_size;
-	int ok;
 
 	if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
 		D_ASSERT(mdev->ldev->backing_bdev);
 		d_size = drbd_get_max_capacity(mdev->ldev);
-		u_size = mdev->ldev->dc.disk_size;
+		rcu_read_lock();
+		u_size = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
+		rcu_read_unlock();
 		q_order_type = drbd_queue_order_type(mdev);
 		max_bio_size = queue_max_hw_sectors(mdev->ldev->backing_bdev->bd_disk->queue) << 9;
 		max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE);
@@ -2230,20 +934,23 @@
 		max_bio_size = DRBD_MAX_BIO_SIZE; /* ... multiple BIOs per peer_request */
 	}
 
-	/* Never allow old drbd (up to 8.3.7) to see more than 32KiB */
-	if (mdev->agreed_pro_version <= 94)
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+
+	if (mdev->tconn->agreed_pro_version <= 94)
 		max_bio_size = min(max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+	else if (mdev->tconn->agreed_pro_version < 100)
+		max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE_P95);
 
-	p.d_size = cpu_to_be64(d_size);
-	p.u_size = cpu_to_be64(u_size);
-	p.c_size = cpu_to_be64(trigger_reply ? 0 : drbd_get_capacity(mdev->this_bdev));
-	p.max_bio_size = cpu_to_be32(max_bio_size);
-	p.queue_order_type = cpu_to_be16(q_order_type);
-	p.dds_flags = cpu_to_be16(flags);
-
-	ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_SIZES,
-			   (struct p_header80 *)&p, sizeof(p));
-	return ok;
+	p->d_size = cpu_to_be64(d_size);
+	p->u_size = cpu_to_be64(u_size);
+	p->c_size = cpu_to_be64(trigger_reply ? 0 : drbd_get_capacity(mdev->this_bdev));
+	p->max_bio_size = cpu_to_be32(max_bio_size);
+	p->queue_order_type = cpu_to_be16(q_order_type);
+	p->dds_flags = cpu_to_be16(flags);
+	return drbd_send_command(mdev, sock, P_SIZES, sizeof(*p), NULL, 0);
 }
 
 /**
@@ -2252,34 +959,21 @@
  */
 int drbd_send_current_state(struct drbd_conf *mdev)
 {
-	struct socket *sock;
-	struct p_state p;
-	int ok = 0;
+	struct drbd_socket *sock;
+	struct p_state *p;
 
-	/* 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, P_STATE,
-				    (struct p_header80 *)&p, sizeof(p), 0);
-	}
-
-	mutex_unlock(&mdev->data.mutex);
-
-	drbd_state_unlock(mdev);
-	return ok;
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->state = cpu_to_be32(mdev->state.i); /* Within the send mutex */
+	return drbd_send_command(mdev, sock, P_STATE, sizeof(*p), NULL, 0);
 }
 
 /**
  * drbd_send_state() - After a state change, sends the new state to the peer
- * @mdev:	DRBD device.
- * @state:	the state to send, not necessarily the current state.
+ * @mdev:      DRBD device.
+ * @state:     the state to send, not necessarily the current state.
  *
  * Each state change queues an "after_state_ch" work, which will eventually
  * send the resulting new state to the peer. If more state changes happen
@@ -2288,50 +982,95 @@
  */
 int drbd_send_state(struct drbd_conf *mdev, union drbd_state state)
 {
-	struct socket *sock;
-	struct p_state p;
-	int ok = 0;
+	struct drbd_socket *sock;
+	struct p_state *p;
 
-	mutex_lock(&mdev->data.mutex);
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->state = cpu_to_be32(state.i); /* Within the send mutex */
+	return drbd_send_command(mdev, sock, P_STATE, sizeof(*p), NULL, 0);
+}
 
-	p.state = cpu_to_be32(state.i);
-	sock = mdev->data.socket;
+int drbd_send_state_req(struct drbd_conf *mdev, union drbd_state mask, union drbd_state val)
+{
+	struct drbd_socket *sock;
+	struct p_req_state *p;
 
-	if (likely(sock != NULL)) {
-		ok = _drbd_send_cmd(mdev, sock, P_STATE,
-				    (struct p_header80 *)&p, sizeof(p), 0);
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->mask = cpu_to_be32(mask.i);
+	p->val = cpu_to_be32(val.i);
+	return drbd_send_command(mdev, sock, P_STATE_CHG_REQ, sizeof(*p), NULL, 0);
+}
+
+int conn_send_state_req(struct drbd_tconn *tconn, union drbd_state mask, union drbd_state val)
+{
+	enum drbd_packet cmd;
+	struct drbd_socket *sock;
+	struct p_req_state *p;
+
+	cmd = tconn->agreed_pro_version < 100 ? P_STATE_CHG_REQ : P_CONN_ST_CHG_REQ;
+	sock = &tconn->data;
+	p = conn_prepare_command(tconn, sock);
+	if (!p)
+		return -EIO;
+	p->mask = cpu_to_be32(mask.i);
+	p->val = cpu_to_be32(val.i);
+	return conn_send_command(tconn, sock, cmd, sizeof(*p), NULL, 0);
+}
+
+void drbd_send_sr_reply(struct drbd_conf *mdev, enum drbd_state_rv retcode)
+{
+	struct drbd_socket *sock;
+	struct p_req_state_reply *p;
+
+	sock = &mdev->tconn->meta;
+	p = drbd_prepare_command(mdev, sock);
+	if (p) {
+		p->retcode = cpu_to_be32(retcode);
+		drbd_send_command(mdev, sock, P_STATE_CHG_REPLY, sizeof(*p), NULL, 0);
 	}
-
-	mutex_unlock(&mdev->data.mutex);
-
-	return ok;
 }
 
-int drbd_send_state_req(struct drbd_conf *mdev,
-	union drbd_state mask, union drbd_state val)
+void conn_send_sr_reply(struct drbd_tconn *tconn, enum drbd_state_rv retcode)
 {
-	struct p_req_state p;
+	struct drbd_socket *sock;
+	struct p_req_state_reply *p;
+	enum drbd_packet cmd = tconn->agreed_pro_version < 100 ? P_STATE_CHG_REPLY : P_CONN_ST_CHG_REPLY;
 
-	p.mask    = cpu_to_be32(mask.i);
-	p.val     = cpu_to_be32(val.i);
-
-	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_STATE_CHG_REQ,
-			     (struct p_header80 *)&p, sizeof(p));
+	sock = &tconn->meta;
+	p = conn_prepare_command(tconn, sock);
+	if (p) {
+		p->retcode = cpu_to_be32(retcode);
+		conn_send_command(tconn, sock, cmd, sizeof(*p), NULL, 0);
+	}
 }
 
-int drbd_send_sr_reply(struct drbd_conf *mdev, enum drbd_state_rv retcode)
+static void dcbp_set_code(struct p_compressed_bm *p, enum drbd_bitmap_code code)
 {
-	struct p_req_state_reply p;
+	BUG_ON(code & ~0xf);
+	p->encoding = (p->encoding & ~0xf) | code;
+}
 
-	p.retcode    = cpu_to_be32(retcode);
+static void dcbp_set_start(struct p_compressed_bm *p, int set)
+{
+	p->encoding = (p->encoding & ~0x80) | (set ? 0x80 : 0);
+}
 
-	return drbd_send_cmd(mdev, USE_META_SOCKET, P_STATE_CHG_REPLY,
-			     (struct p_header80 *)&p, sizeof(p));
+static void dcbp_set_pad_bits(struct p_compressed_bm *p, int n)
+{
+	BUG_ON(n & ~0x7);
+	p->encoding = (p->encoding & (~0x7 << 4)) | (n << 4);
 }
 
 int fill_bitmap_rle_bits(struct drbd_conf *mdev,
-	struct p_compressed_bm *p,
-	struct bm_xfer_ctx *c)
+			 struct p_compressed_bm *p,
+			 unsigned int size,
+			 struct bm_xfer_ctx *c)
 {
 	struct bitstream bs;
 	unsigned long plain_bits;
@@ -2339,19 +1078,21 @@
 	unsigned long rl;
 	unsigned len;
 	unsigned toggle;
-	int bits;
+	int bits, use_rle;
 
 	/* may we use this feature? */
-	if ((mdev->sync_conf.use_rle == 0) ||
-		(mdev->agreed_pro_version < 90))
-			return 0;
+	rcu_read_lock();
+	use_rle = rcu_dereference(mdev->tconn->net_conf)->use_rle;
+	rcu_read_unlock();
+	if (!use_rle || mdev->tconn->agreed_pro_version < 90)
+		return 0;
 
 	if (c->bit_offset >= c->bm_bits)
 		return 0; /* nothing to do. */
 
 	/* use at most thus many bytes */
-	bitstream_init(&bs, p->code, BM_PACKET_VLI_BYTES_MAX, 0);
-	memset(p->code, 0, BM_PACKET_VLI_BYTES_MAX);
+	bitstream_init(&bs, p->code, size, 0);
+	memset(p->code, 0, size);
 	/* plain bits covered in this code string */
 	plain_bits = 0;
 
@@ -2373,12 +1114,12 @@
 			if (rl == 0) {
 				/* the first checked bit was set,
 				 * store start value, */
-				DCBP_set_start(p, 1);
+				dcbp_set_start(p, 1);
 				/* but skip encoding of zero run length */
 				toggle = !toggle;
 				continue;
 			}
-			DCBP_set_start(p, 0);
+			dcbp_set_start(p, 0);
 		}
 
 		/* paranoia: catch zero runlength.
@@ -2418,7 +1159,7 @@
 	bm_xfer_ctx_bit_to_word_offset(c);
 
 	/* store pad_bits */
-	DCBP_set_pad_bits(p, (8 - bs.cur.bit) & 0x7);
+	dcbp_set_pad_bits(p, (8 - bs.cur.bit) & 0x7);
 
 	return len;
 }
@@ -2430,48 +1171,52 @@
  * code upon failure.
  */
 static int
-send_bitmap_rle_or_plain(struct drbd_conf *mdev,
-			 struct p_header80 *h, struct bm_xfer_ctx *c)
+send_bitmap_rle_or_plain(struct drbd_conf *mdev, struct bm_xfer_ctx *c)
 {
-	struct p_compressed_bm *p = (void*)h;
-	unsigned long num_words;
-	int len;
-	int ok;
+	struct drbd_socket *sock = &mdev->tconn->data;
+	unsigned int header_size = drbd_header_size(mdev->tconn);
+	struct p_compressed_bm *p = sock->sbuf + header_size;
+	int len, err;
 
-	len = fill_bitmap_rle_bits(mdev, p, c);
-
+	len = fill_bitmap_rle_bits(mdev, p,
+			DRBD_SOCKET_BUFFER_SIZE - header_size - sizeof(*p), c);
 	if (len < 0)
 		return -EIO;
 
 	if (len) {
-		DCBP_set_code(p, RLE_VLI_Bits);
-		ok = _drbd_send_cmd(mdev, mdev->data.socket, P_COMPRESSED_BITMAP, h,
-			sizeof(*p) + len, 0);
-
+		dcbp_set_code(p, RLE_VLI_Bits);
+		err = __send_command(mdev->tconn, mdev->vnr, sock,
+				     P_COMPRESSED_BITMAP, sizeof(*p) + len,
+				     NULL, 0);
 		c->packets[0]++;
-		c->bytes[0] += sizeof(*p) + len;
+		c->bytes[0] += header_size + sizeof(*p) + len;
 
 		if (c->bit_offset >= c->bm_bits)
 			len = 0; /* DONE */
 	} else {
 		/* was not compressible.
 		 * send a buffer full of plain text bits instead. */
-		num_words = min_t(size_t, BM_PACKET_WORDS, c->bm_words - c->word_offset);
-		len = num_words * sizeof(long);
+		unsigned int data_size;
+		unsigned long num_words;
+		unsigned long *p = sock->sbuf + header_size;
+
+		data_size = DRBD_SOCKET_BUFFER_SIZE - header_size;
+		num_words = min_t(size_t, data_size / sizeof(*p),
+				  c->bm_words - c->word_offset);
+		len = num_words * sizeof(*p);
 		if (len)
-			drbd_bm_get_lel(mdev, c->word_offset, num_words, (unsigned long*)h->payload);
-		ok = _drbd_send_cmd(mdev, mdev->data.socket, P_BITMAP,
-				   h, sizeof(struct p_header80) + len, 0);
+			drbd_bm_get_lel(mdev, c->word_offset, num_words, p);
+		err = __send_command(mdev->tconn, mdev->vnr, sock, P_BITMAP, len, NULL, 0);
 		c->word_offset += num_words;
 		c->bit_offset = c->word_offset * BITS_PER_LONG;
 
 		c->packets[1]++;
-		c->bytes[1] += sizeof(struct p_header80) + len;
+		c->bytes[1] += header_size + len;
 
 		if (c->bit_offset > c->bm_bits)
 			c->bit_offset = c->bm_bits;
 	}
-	if (ok) {
+	if (!err) {
 		if (len == 0) {
 			INFO_bm_xfer_stats(mdev, "send", c);
 			return 0;
@@ -2482,21 +1227,13 @@
 }
 
 /* See the comment at receive_bitmap() */
-int _drbd_send_bitmap(struct drbd_conf *mdev)
+static int _drbd_send_bitmap(struct drbd_conf *mdev)
 {
 	struct bm_xfer_ctx c;
-	struct p_header80 *p;
 	int err;
 
-	ERR_IF(!mdev->bitmap) return false;
-
-	/* maybe we should use some per thread scratch page,
-	 * and allocate that during initial device creation? */
-	p = (struct p_header80 *) __get_free_page(GFP_NOIO);
-	if (!p) {
-		dev_err(DEV, "failed to allocate one page buffer in %s\n", __func__);
+	if (!expect(mdev->bitmap))
 		return false;
-	}
 
 	if (get_ldev(mdev)) {
 		if (drbd_md_test_flag(mdev->ldev, MDF_FULL_SYNC)) {
@@ -2521,37 +1258,39 @@
 	};
 
 	do {
-		err = send_bitmap_rle_or_plain(mdev, p, &c);
+		err = send_bitmap_rle_or_plain(mdev, &c);
 	} while (err > 0);
 
-	free_page((unsigned long) p);
 	return err == 0;
 }
 
 int drbd_send_bitmap(struct drbd_conf *mdev)
 {
-	int err;
+	struct drbd_socket *sock = &mdev->tconn->data;
+	int err = -1;
 
-	if (!drbd_get_data_sock(mdev))
-		return -1;
-	err = !_drbd_send_bitmap(mdev);
-	drbd_put_data_sock(mdev);
+	mutex_lock(&sock->mutex);
+	if (sock->socket)
+		err = !_drbd_send_bitmap(mdev);
+	mutex_unlock(&sock->mutex);
 	return err;
 }
 
-int drbd_send_b_ack(struct drbd_conf *mdev, u32 barrier_nr, u32 set_size)
+void drbd_send_b_ack(struct drbd_tconn *tconn, u32 barrier_nr, u32 set_size)
 {
-	int ok;
-	struct p_barrier_ack p;
+	struct drbd_socket *sock;
+	struct p_barrier_ack *p;
 
-	p.barrier  = barrier_nr;
-	p.set_size = cpu_to_be32(set_size);
+	if (tconn->cstate < C_WF_REPORT_PARAMS)
+		return;
 
-	if (mdev->state.conn < C_CONNECTED)
-		return false;
-	ok = drbd_send_cmd(mdev, USE_META_SOCKET, P_BARRIER_ACK,
-			(struct p_header80 *)&p, sizeof(p));
-	return ok;
+	sock = &tconn->meta;
+	p = conn_prepare_command(tconn, sock);
+	if (!p)
+		return;
+	p->barrier = barrier_nr;
+	p->set_size = cpu_to_be32(set_size);
+	conn_send_command(tconn, sock, P_BARRIER_ACK, sizeof(*p), NULL, 0);
 }
 
 /**
@@ -2562,62 +1301,62 @@
  * @blksize:	size in byte, needs to be in big endian byte order
  * @block_id:	Id, big endian byte order
  */
-static int _drbd_send_ack(struct drbd_conf *mdev, enum drbd_packets cmd,
-			  u64 sector,
-			  u32 blksize,
-			  u64 block_id)
+static int _drbd_send_ack(struct drbd_conf *mdev, enum drbd_packet cmd,
+			  u64 sector, u32 blksize, u64 block_id)
 {
-	int ok;
-	struct p_block_ack p;
+	struct drbd_socket *sock;
+	struct p_block_ack *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->state.conn < C_CONNECTED)
+		return -EIO;
 
-	if (!mdev->meta.socket || mdev->state.conn < C_CONNECTED)
-		return false;
-	ok = drbd_send_cmd(mdev, USE_META_SOCKET, cmd,
-				(struct p_header80 *)&p, sizeof(p));
-	return ok;
+	sock = &mdev->tconn->meta;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->sector = sector;
+	p->block_id = block_id;
+	p->blksize = blksize;
+	p->seq_num = cpu_to_be32(atomic_inc_return(&mdev->packet_seq));
+	return drbd_send_command(mdev, sock, cmd, sizeof(*p), NULL, 0);
 }
 
 /* dp->sector and dp->block_id already/still in network byte order,
  * data_size is payload size according to dp->head,
  * and may need to be corrected for digest size. */
-int drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packets cmd,
-		     struct p_data *dp, int data_size)
+void drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packet cmd,
+		      struct p_data *dp, int data_size)
 {
-	data_size -= (mdev->agreed_pro_version >= 87 && mdev->integrity_r_tfm) ?
-		crypto_hash_digestsize(mdev->integrity_r_tfm) : 0;
-	return _drbd_send_ack(mdev, cmd, dp->sector, cpu_to_be32(data_size),
-			      dp->block_id);
+	if (mdev->tconn->peer_integrity_tfm)
+		data_size -= crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm);
+	_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_packets cmd,
-		     struct p_block_req *rp)
+void drbd_send_ack_rp(struct drbd_conf *mdev, enum drbd_packet cmd,
+		      struct p_block_req *rp)
 {
-	return _drbd_send_ack(mdev, cmd, rp->sector, rp->blksize, rp->block_id);
+	_drbd_send_ack(mdev, cmd, rp->sector, rp->blksize, rp->block_id);
 }
 
 /**
  * drbd_send_ack() - Sends an ack packet
- * @mdev:	DRBD device.
- * @cmd:	Packet command code.
- * @e:		Epoch entry.
+ * @mdev:	DRBD device
+ * @cmd:	packet command code
+ * @peer_req:	peer request
  */
-int drbd_send_ack(struct drbd_conf *mdev,
-	enum drbd_packets cmd, struct drbd_epoch_entry *e)
+int drbd_send_ack(struct drbd_conf *mdev, enum drbd_packet cmd,
+		  struct drbd_peer_request *peer_req)
 {
 	return _drbd_send_ack(mdev, cmd,
-			      cpu_to_be64(e->sector),
-			      cpu_to_be32(e->size),
-			      e->block_id);
+			      cpu_to_be64(peer_req->i.sector),
+			      cpu_to_be32(peer_req->i.size),
+			      peer_req->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_packets cmd,
+int drbd_send_ack_ex(struct drbd_conf *mdev, enum drbd_packet cmd,
 		     sector_t sector, int blksize, u64 block_id)
 {
 	return _drbd_send_ack(mdev, cmd,
@@ -2629,85 +1368,87 @@
 int drbd_send_drequest(struct drbd_conf *mdev, int cmd,
 		       sector_t sector, int size, u64 block_id)
 {
-	int ok;
-	struct p_block_req p;
+	struct drbd_socket *sock;
+	struct p_block_req *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 p_header80 *)&p, sizeof(p));
-	return ok;
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->sector = cpu_to_be64(sector);
+	p->block_id = block_id;
+	p->blksize = cpu_to_be32(size);
+	return drbd_send_command(mdev, sock, cmd, sizeof(*p), NULL, 0);
 }
 
-int drbd_send_drequest_csum(struct drbd_conf *mdev,
-			    sector_t sector, int size,
-			    void *digest, int digest_size,
-			    enum drbd_packets cmd)
+int drbd_send_drequest_csum(struct drbd_conf *mdev, sector_t sector, int size,
+			    void *digest, int digest_size, enum drbd_packet cmd)
 {
-	int ok;
-	struct p_block_req p;
+	struct drbd_socket *sock;
+	struct p_block_req *p;
 
-	p.sector   = cpu_to_be64(sector);
-	p.block_id = BE_DRBD_MAGIC + 0xbeef;
-	p.blksize  = cpu_to_be32(size);
+	/* FIXME: Put the digest into the preallocated socket buffer.  */
 
-	p.head.magic   = BE_DRBD_MAGIC;
-	p.head.command = cpu_to_be16(cmd);
-	p.head.length  = cpu_to_be16(sizeof(p) - sizeof(struct p_header80) + 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;
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->sector = cpu_to_be64(sector);
+	p->block_id = ID_SYNCER /* unused */;
+	p->blksize = cpu_to_be32(size);
+	return drbd_send_command(mdev, sock, cmd, sizeof(*p),
+				 digest, digest_size);
 }
 
 int drbd_send_ov_request(struct drbd_conf *mdev, sector_t sector, int size)
 {
-	int ok;
-	struct p_block_req p;
+	struct drbd_socket *sock;
+	struct p_block_req *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, P_OV_REQUEST,
-			   (struct p_header80 *)&p, sizeof(p));
-	return ok;
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->sector = cpu_to_be64(sector);
+	p->block_id = ID_SYNCER /* unused */;
+	p->blksize = cpu_to_be32(size);
+	return drbd_send_command(mdev, sock, P_OV_REQUEST, sizeof(*p), NULL, 0);
 }
 
 /* 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)
+static int we_should_drop_the_connection(struct drbd_tconn *tconn, 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 < C_CONNECTED;
+	drop_it =   tconn->meta.socket == sock
+		|| !tconn->asender.task
+		|| get_t_state(&tconn->asender) != RUNNING
+		|| tconn->cstate < C_WF_REPORT_PARAMS;
 
 	if (drop_it)
 		return true;
 
-	drop_it = !--mdev->ko_count;
+	drop_it = !--tconn->ko_count;
 	if (!drop_it) {
-		dev_err(DEV, "[%s/%d] sock_sendmsg time expired, ko = %u\n",
-		       current->comm, current->pid, mdev->ko_count);
-		request_ping(mdev);
+		conn_err(tconn, "[%s/%d] sock_sendmsg time expired, ko = %u\n",
+			 current->comm, current->pid, tconn->ko_count);
+		request_ping(tconn);
 	}
 
 	return drop_it; /* && (mdev->state == R_PRIMARY) */;
 }
 
+static void drbd_update_congested(struct drbd_tconn *tconn)
+{
+	struct sock *sk = tconn->data.socket->sk;
+	if (sk->sk_wmem_queued > sk->sk_sndbuf * 4 / 5)
+		set_bit(NET_CONGESTED, &tconn->flags);
+}
+
 /* 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.
@@ -2730,21 +1471,28 @@
  * with page_count == 0 or PageSlab.
  */
 static int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page,
-		   int offset, size_t size, unsigned msg_flags)
+			      int offset, size_t size, unsigned msg_flags)
 {
-	int sent = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, msg_flags);
+	struct socket *socket;
+	void *addr;
+	int err;
+
+	socket = mdev->tconn->data.socket;
+	addr = kmap(page) + offset;
+	err = drbd_send_all(mdev->tconn, socket, addr, size, msg_flags);
 	kunmap(page);
-	if (sent == size)
-		mdev->send_cnt += size>>9;
-	return sent == size;
+	if (!err)
+		mdev->send_cnt += size >> 9;
+	return err;
 }
 
 static int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
 		    int offset, size_t size, unsigned msg_flags)
 {
+	struct socket *socket = mdev->tconn->data.socket;
 	mm_segment_t oldfs = get_fs();
-	int sent, ok;
 	int len = size;
+	int err = -EIO;
 
 	/* e.g. XFS meta- & log-data is in slab pages, which have a
 	 * page_count of 0 and/or have PageSlab() set.
@@ -2756,34 +1504,35 @@
 		return _drbd_no_send_page(mdev, page, offset, size, msg_flags);
 
 	msg_flags |= MSG_NOSIGNAL;
-	drbd_update_congested(mdev);
+	drbd_update_congested(mdev->tconn);
 	set_fs(KERNEL_DS);
 	do {
-		sent = mdev->data.socket->ops->sendpage(mdev->data.socket, page,
-							offset, len,
-							msg_flags);
-		if (sent == -EAGAIN) {
-			if (we_should_drop_the_connection(mdev,
-							  mdev->data.socket))
-				break;
-			else
-				continue;
-		}
+		int sent;
+
+		sent = socket->ops->sendpage(socket, page, offset, len, msg_flags);
 		if (sent <= 0) {
+			if (sent == -EAGAIN) {
+				if (we_should_drop_the_connection(mdev->tconn, socket))
+					break;
+				continue;
+			}
 			dev_warn(DEV, "%s: size=%d len=%d sent=%d\n",
 			     __func__, (int)size, len, sent);
+			if (sent < 0)
+				err = sent;
 			break;
 		}
 		len    -= sent;
 		offset += sent;
 	} while (len > 0 /* THINK && mdev->cstate >= C_CONNECTED*/);
 	set_fs(oldfs);
-	drbd_clear_flag(mdev, NET_CONGESTED);
+	clear_bit(NET_CONGESTED, &mdev->tconn->flags);
 
-	ok = (len == 0);
-	if (likely(ok))
-		mdev->send_cnt += size>>9;
-	return ok;
+	if (len == 0) {
+		err = 0;
+		mdev->send_cnt += size >> 9;
+	}
+	return err;
 }
 
 static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio)
@@ -2792,12 +1541,15 @@
 	int i;
 	/* hint all but last page with MSG_MORE */
 	bio_for_each_segment(bvec, bio, i) {
-		if (!_drbd_no_send_page(mdev, bvec->bv_page,
-				     bvec->bv_offset, bvec->bv_len,
-				     i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
-			return 0;
+		int err;
+
+		err = _drbd_no_send_page(mdev, bvec->bv_page,
+					 bvec->bv_offset, bvec->bv_len,
+					 i == bio->bi_vcnt - 1 ? 0 : MSG_MORE);
+		if (err)
+			return err;
 	}
-	return 1;
+	return 0;
 }
 
 static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
@@ -2806,32 +1558,40 @@
 	int i;
 	/* hint all but last page with MSG_MORE */
 	bio_for_each_segment(bvec, bio, i) {
-		if (!_drbd_send_page(mdev, bvec->bv_page,
-				     bvec->bv_offset, bvec->bv_len,
-				     i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
-			return 0;
+		int err;
+
+		err = _drbd_send_page(mdev, bvec->bv_page,
+				      bvec->bv_offset, bvec->bv_len,
+				      i == bio->bi_vcnt - 1 ? 0 : MSG_MORE);
+		if (err)
+			return err;
 	}
-	return 1;
+	return 0;
 }
 
-static int _drbd_send_zc_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
+static int _drbd_send_zc_ee(struct drbd_conf *mdev,
+			    struct drbd_peer_request *peer_req)
 {
-	struct page *page = e->pages;
-	unsigned len = e->size;
+	struct page *page = peer_req->pages;
+	unsigned len = peer_req->i.size;
+	int err;
+
 	/* hint all but last page with MSG_MORE */
 	page_chain_for_each(page) {
 		unsigned l = min_t(unsigned, len, PAGE_SIZE);
-		if (!_drbd_send_page(mdev, page, 0, l,
-				page_chain_next(page) ? MSG_MORE : 0))
-			return 0;
+
+		err = _drbd_send_page(mdev, page, 0, l,
+				      page_chain_next(page) ? MSG_MORE : 0);
+		if (err)
+			return err;
 		len -= l;
 	}
-	return 1;
+	return 0;
 }
 
 static u32 bio_flags_to_wire(struct drbd_conf *mdev, unsigned long bi_rw)
 {
-	if (mdev->agreed_pro_version >= 95)
+	if (mdev->tconn->agreed_pro_version >= 95)
 		return  (bi_rw & REQ_SYNC ? DP_RW_SYNC : 0) |
 			(bi_rw & REQ_FUA ? DP_FUA : 0) |
 			(bi_rw & REQ_FLUSH ? DP_FLUSH : 0) |
@@ -2845,50 +1605,36 @@
  */
 int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
 {
-	int ok = 1;
-	struct p_data p;
+	struct drbd_socket *sock;
+	struct p_data *p;
 	unsigned int dp_flags = 0;
-	void *dgb;
 	int dgs;
+	int err;
 
-	if (!drbd_get_data_sock(mdev))
-		return 0;
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	dgs = mdev->tconn->integrity_tfm ? crypto_hash_digestsize(mdev->tconn->integrity_tfm) : 0;
 
-	dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
-		crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;
-
-	if (req->size <= DRBD_MAX_SIZE_H80_PACKET) {
-		p.head.h80.magic   = BE_DRBD_MAGIC;
-		p.head.h80.command = cpu_to_be16(P_DATA);
-		p.head.h80.length  =
-			cpu_to_be16(sizeof(p) - sizeof(union p_header) + dgs + req->size);
-	} else {
-		p.head.h95.magic   = BE_DRBD_MAGIC_BIG;
-		p.head.h95.command = cpu_to_be16(P_DATA);
-		p.head.h95.length  =
-			cpu_to_be32(sizeof(p) - sizeof(union p_header) + dgs + req->size);
-	}
-
-	p.sector   = cpu_to_be64(req->sector);
-	p.block_id = (unsigned long)req;
-	p.seq_num  = cpu_to_be32(atomic_add_return(1, &mdev->packet_seq));
-
+	if (!p)
+		return -EIO;
+	p->sector = cpu_to_be64(req->i.sector);
+	p->block_id = (unsigned long)req;
+	p->seq_num = cpu_to_be32(atomic_inc_return(&mdev->packet_seq));
 	dp_flags = bio_flags_to_wire(mdev, req->master_bio->bi_rw);
-
 	if (mdev->state.conn >= C_SYNC_SOURCE &&
 	    mdev->state.conn <= C_PAUSED_SYNC_T)
 		dp_flags |= DP_MAY_SET_IN_SYNC;
-
-	p.dp_flags = cpu_to_be32(dp_flags);
-	drbd_set_flag(mdev, UNPLUG_REMOTE);
-	ok = (sizeof(p) ==
-		drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0));
-	if (ok && dgs) {
-		dgb = mdev->int_dig_out;
-		drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);
-		ok = dgs == drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
+	if (mdev->tconn->agreed_pro_version >= 100) {
+		if (req->rq_state & RQ_EXP_RECEIVE_ACK)
+			dp_flags |= DP_SEND_RECEIVE_ACK;
+		if (req->rq_state & RQ_EXP_WRITE_ACK)
+			dp_flags |= DP_SEND_WRITE_ACK;
 	}
-	if (ok) {
+	p->dp_flags = cpu_to_be32(dp_flags);
+	if (dgs)
+		drbd_csum_bio(mdev, mdev->tconn->integrity_tfm, req->master_bio, p + 1);
+	err = __send_command(mdev->tconn, mdev->vnr, sock, P_DATA, sizeof(*p) + dgs, NULL, req->i.size);
+	if (!err) {
 		/* For protocol A, we have to memcpy the payload into
 		 * socket buffers, as we may complete right away
 		 * as soon as we handed it over to tcp, at which point the data
@@ -2900,92 +1646,76 @@
 		 * out ok after sending on this side, but does not fit on the
 		 * receiving side, we sure have detected corruption elsewhere.
 		 */
-		if (mdev->net_conf->wire_protocol == DRBD_PROT_A || dgs)
-			ok = _drbd_send_bio(mdev, req->master_bio);
+		if (!(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK)) || dgs)
+			err = _drbd_send_bio(mdev, req->master_bio);
 		else
-			ok = _drbd_send_zc_bio(mdev, req->master_bio);
+			err = _drbd_send_zc_bio(mdev, req->master_bio);
 
 		/* double check digest, sometimes buffers have been modified in flight. */
 		if (dgs > 0 && dgs <= 64) {
 			/* 64 byte, 512 bit, is the largest digest size
 			 * currently supported in kernel crypto. */
 			unsigned char digest[64];
-			drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, digest);
-			if (memcmp(mdev->int_dig_out, digest, dgs)) {
+			drbd_csum_bio(mdev, mdev->tconn->integrity_tfm, req->master_bio, digest);
+			if (memcmp(p + 1, digest, dgs)) {
 				dev_warn(DEV,
 					"Digest mismatch, buffer modified by upper layers during write: %llus +%u\n",
-					(unsigned long long)req->sector, req->size);
+					(unsigned long long)req->i.sector, req->i.size);
 			}
 		} /* else if (dgs > 64) {
 		     ... Be noisy about digest too large ...
 		} */
 	}
+	mutex_unlock(&sock->mutex);  /* locked by drbd_prepare_command() */
 
-	drbd_put_data_sock(mdev);
-
-	return ok;
+	return err;
 }
 
 /* answer packet, used to send data back for read requests:
  *  Peer       -> (diskless) R_PRIMARY   (P_DATA_REPLY)
  *  C_SYNC_SOURCE -> C_SYNC_TARGET         (P_RS_DATA_REPLY)
  */
-int drbd_send_block(struct drbd_conf *mdev, enum drbd_packets cmd,
-		    struct drbd_epoch_entry *e)
+int drbd_send_block(struct drbd_conf *mdev, enum drbd_packet cmd,
+		    struct drbd_peer_request *peer_req)
 {
-	int ok;
-	struct p_data p;
-	void *dgb;
+	struct drbd_socket *sock;
+	struct p_data *p;
+	int err;
 	int dgs;
 
-	dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
-		crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
 
-	if (e->size <= DRBD_MAX_SIZE_H80_PACKET) {
-		p.head.h80.magic   = BE_DRBD_MAGIC;
-		p.head.h80.command = cpu_to_be16(cmd);
-		p.head.h80.length  =
-			cpu_to_be16(sizeof(p) - sizeof(struct p_header80) + dgs + e->size);
-	} else {
-		p.head.h95.magic   = BE_DRBD_MAGIC_BIG;
-		p.head.h95.command = cpu_to_be16(cmd);
-		p.head.h95.length  =
-			cpu_to_be32(sizeof(p) - sizeof(struct p_header80) + dgs + e->size);
-	}
+	dgs = mdev->tconn->integrity_tfm ? crypto_hash_digestsize(mdev->tconn->integrity_tfm) : 0;
 
-	p.sector   = cpu_to_be64(e->sector);
-	p.block_id = e->block_id;
-	/* p.seq_num  = 0;    No sequence numbers here.. */
+	if (!p)
+		return -EIO;
+	p->sector = cpu_to_be64(peer_req->i.sector);
+	p->block_id = peer_req->block_id;
+	p->seq_num = 0;  /* unused */
+	p->dp_flags = 0;
+	if (dgs)
+		drbd_csum_ee(mdev, mdev->tconn->integrity_tfm, peer_req, p + 1);
+	err = __send_command(mdev->tconn, mdev->vnr, sock, cmd, sizeof(*p) + dgs, NULL, peer_req->i.size);
+	if (!err)
+		err = _drbd_send_zc_ee(mdev, peer_req);
+	mutex_unlock(&sock->mutex);  /* locked by drbd_prepare_command() */
 
-	/* Only called by our kernel thread.
-	 * This one may be interrupted by DRBD_SIG and/or DRBD_SIGKILL
-	 * in response to admin command or module unload.
-	 */
-	if (!drbd_get_data_sock(mdev))
-		return 0;
-
-	ok = sizeof(p) == drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0);
-	if (ok && dgs) {
-		dgb = mdev->int_dig_out;
-		drbd_csum_ee(mdev, mdev->integrity_w_tfm, e, dgb);
-		ok = dgs == drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
-	}
-	if (ok)
-		ok = _drbd_send_zc_ee(mdev, e);
-
-	drbd_put_data_sock(mdev);
-
-	return ok;
+	return err;
 }
 
-int drbd_send_oos(struct drbd_conf *mdev, struct drbd_request *req)
+int drbd_send_out_of_sync(struct drbd_conf *mdev, struct drbd_request *req)
 {
-	struct p_block_desc p;
+	struct drbd_socket *sock;
+	struct p_block_desc *p;
 
-	p.sector  = cpu_to_be64(req->sector);
-	p.blksize = cpu_to_be32(req->size);
-
-	return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_OUT_OF_SYNC, &p.head, sizeof(p));
+	sock = &mdev->tconn->data;
+	p = drbd_prepare_command(mdev, sock);
+	if (!p)
+		return -EIO;
+	p->sector = cpu_to_be64(req->i.sector);
+	p->blksize = cpu_to_be32(req->i.size);
+	return drbd_send_command(mdev, sock, P_OUT_OF_SYNC, sizeof(*p), NULL, 0);
 }
 
 /*
@@ -3004,7 +1734,7 @@
 /*
  * you must have down()ed the appropriate [m]sock_mutex elsewhere!
  */
-int drbd_send(struct drbd_conf *mdev, struct socket *sock,
+int drbd_send(struct drbd_tconn *tconn, struct socket *sock,
 	      void *buf, size_t size, unsigned msg_flags)
 {
 	struct kvec iov;
@@ -3012,7 +1742,7 @@
 	int rv, sent = 0;
 
 	if (!sock)
-		return -1000;
+		return -EBADR;
 
 	/* THINK  if (signal_pending) return ... ? */
 
@@ -3025,9 +1755,11 @@
 	msg.msg_controllen = 0;
 	msg.msg_flags      = msg_flags | MSG_NOSIGNAL;
 
-	if (sock == mdev->data.socket) {
-		mdev->ko_count = mdev->net_conf->ko_count;
-		drbd_update_congested(mdev);
+	if (sock == tconn->data.socket) {
+		rcu_read_lock();
+		tconn->ko_count = rcu_dereference(tconn->net_conf)->ko_count;
+		rcu_read_unlock();
+		drbd_update_congested(tconn);
 	}
 	do {
 		/* STRANGE
@@ -3041,12 +1773,11 @@
  */
 		rv = kernel_sendmsg(sock, &msg, &iov, 1, size);
 		if (rv == -EAGAIN) {
-			if (we_should_drop_the_connection(mdev, sock))
+			if (we_should_drop_the_connection(tconn, sock))
 				break;
 			else
 				continue;
 		}
-		D_ASSERT(rv != 0);
 		if (rv == -EINTR) {
 			flush_signals(current);
 			rv = 0;
@@ -3058,22 +1789,40 @@
 		iov.iov_len  -= rv;
 	} while (sent < size);
 
-	if (sock == mdev->data.socket)
-		drbd_clear_flag(mdev, NET_CONGESTED);
+	if (sock == tconn->data.socket)
+		clear_bit(NET_CONGESTED, &tconn->flags);
 
 	if (rv <= 0) {
 		if (rv != -EAGAIN) {
-			dev_err(DEV, "%s_sendmsg returned %d\n",
-			    sock == mdev->meta.socket ? "msock" : "sock",
-			    rv);
-			drbd_force_state(mdev, NS(conn, C_BROKEN_PIPE));
+			conn_err(tconn, "%s_sendmsg returned %d\n",
+				 sock == tconn->meta.socket ? "msock" : "sock",
+				 rv);
+			conn_request_state(tconn, NS(conn, C_BROKEN_PIPE), CS_HARD);
 		} else
-			drbd_force_state(mdev, NS(conn, C_TIMEOUT));
+			conn_request_state(tconn, NS(conn, C_TIMEOUT), CS_HARD);
 	}
 
 	return sent;
 }
 
+/**
+ * drbd_send_all  -  Send an entire buffer
+ *
+ * Returns 0 upon success and a negative error value otherwise.
+ */
+int drbd_send_all(struct drbd_tconn *tconn, struct socket *sock, void *buffer,
+		  size_t size, unsigned msg_flags)
+{
+	int err;
+
+	err = drbd_send(tconn, sock, buffer, size, msg_flags);
+	if (err < 0)
+		return err;
+	if (err != size)
+		return -EIO;
+	return 0;
+}
+
 static int drbd_open(struct block_device *bdev, fmode_t mode)
 {
 	struct drbd_conf *mdev = bdev->bd_disk->private_data;
@@ -3081,7 +1830,7 @@
 	int rv = 0;
 
 	mutex_lock(&drbd_main_mutex);
-	spin_lock_irqsave(&mdev->req_lock, flags);
+	spin_lock_irqsave(&mdev->tconn->req_lock, flags);
 	/* to have a stable mdev->state.role
 	 * and no race with updating open_cnt */
 
@@ -3094,7 +1843,7 @@
 
 	if (!rv)
 		mdev->open_cnt++;
-	spin_unlock_irqrestore(&mdev->req_lock, flags);
+	spin_unlock_irqrestore(&mdev->tconn->req_lock, flags);
 	mutex_unlock(&drbd_main_mutex);
 
 	return rv;
@@ -3111,35 +1860,14 @@
 
 static void drbd_set_defaults(struct drbd_conf *mdev)
 {
-	/* This way we get a compile error when sync_conf grows,
-	   and we forgot to initialize it here */
-	mdev->sync_conf = (struct syncer_conf) {
-		/* .rate = */		DRBD_RATE_DEF,
-		/* .after = */		DRBD_AFTER_DEF,
-		/* .al_extents = */	DRBD_AL_EXTENTS_DEF,
-		/* .verify_alg = */	{}, 0,
-		/* .cpu_mask = */	{}, 0,
-		/* .csums_alg = */	{}, 0,
-		/* .use_rle = */	0,
-		/* .on_no_data = */	DRBD_ON_NO_DATA_DEF,
-		/* .c_plan_ahead = */	DRBD_C_PLAN_AHEAD_DEF,
-		/* .c_delay_target = */	DRBD_C_DELAY_TARGET_DEF,
-		/* .c_fill_target = */	DRBD_C_FILL_TARGET_DEF,
-		/* .c_max_rate = */	DRBD_C_MAX_RATE_DEF,
-		/* .c_min_rate = */	DRBD_C_MIN_RATE_DEF
-	};
-
-	/* Have to use that way, because the layout differs between
-	   big endian and little endian */
-	mdev->state = (union drbd_state) {
+	/* Beware! The actual layout differs
+	 * between big endian and little endian */
+	mdev->state = (union drbd_dev_state) {
 		{ .role = R_SECONDARY,
 		  .peer = R_UNKNOWN,
 		  .conn = C_STANDALONE,
 		  .disk = D_DISKLESS,
 		  .pdsk = D_UNKNOWN,
-		  .susp = 0,
-		  .susp_nod = 0,
-		  .susp_fen = 0
 		} };
 }
 
@@ -3155,28 +1883,17 @@
 	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);
 	atomic_set(&mdev->pp_in_use_by_net, 0);
 	atomic_set(&mdev->rs_sect_in, 0);
 	atomic_set(&mdev->rs_sect_ev, 0);
 	atomic_set(&mdev->ap_in_flight, 0);
 	atomic_set(&mdev->md_io_in_use, 0);
 
-	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);
+	mutex_init(&mdev->own_state_mutex);
+	mdev->state_mutex = &mdev->own_state_mutex;
 
 	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);
@@ -3184,8 +1901,6 @@
 	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->go_diskless.list);
@@ -3199,6 +1914,14 @@
 	mdev->md_sync_work.cb = w_md_sync;
 	mdev->bm_io_work.w.cb = w_bitmap_io;
 	mdev->start_resync_work.cb = w_start_resync;
+
+	mdev->resync_work.mdev  = mdev;
+	mdev->unplug_work.mdev  = mdev;
+	mdev->go_diskless.mdev  = mdev;
+	mdev->md_sync_work.mdev = mdev;
+	mdev->bm_io_work.w.mdev = mdev;
+	mdev->start_resync_work.mdev = mdev;
+
 	init_timer(&mdev->resync_timer);
 	init_timer(&mdev->md_sync_timer);
 	init_timer(&mdev->start_resync_timer);
@@ -3214,17 +1937,10 @@
 
 	init_waitqueue_head(&mdev->misc_wait);
 	init_waitqueue_head(&mdev->state_wait);
-	init_waitqueue_head(&mdev->net_cnt_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_bdev_flush;
 	mdev->resync_wenr = LC_FREE;
 	mdev->peer_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
 	mdev->local_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
@@ -3233,13 +1949,10 @@
 void drbd_mdev_cleanup(struct drbd_conf *mdev)
 {
 	int i;
-	if (mdev->receiver.t_state != None)
+	if (mdev->tconn->receiver.t_state != NONE)
 		dev_err(DEV, "ASSERT FAILED: receiver t_state == %d expected 0.\n",
-				mdev->receiver.t_state);
+				mdev->tconn->receiver.t_state);
 
-	/* no need to lock it, I'm the only thread alive */
-	if (atomic_read(&mdev->current_epoch->epoch_size) !=  0)
-		dev_err(DEV, "epoch_size:%d\n", atomic_read(&mdev->current_epoch->epoch_size));
 	mdev->al_writ_cnt  =
 	mdev->bm_writ_cnt  =
 	mdev->read_cnt     =
@@ -3256,7 +1969,7 @@
 		mdev->rs_mark_left[i] = 0;
 		mdev->rs_mark_time[i] = 0;
 	}
-	D_ASSERT(mdev->net_conf == NULL);
+	D_ASSERT(mdev->tconn->net_conf == NULL);
 
 	drbd_set_my_capacity(mdev, 0);
 	if (mdev->bitmap) {
@@ -3265,21 +1978,18 @@
 		drbd_bm_cleanup(mdev);
 	}
 
-	drbd_free_resources(mdev);
-	drbd_clear_flag(mdev, AL_SUSPENDED);
+	drbd_free_bc(mdev->ldev);
+	mdev->ldev = NULL;
 
-	/*
-	 * currently we drbd_init_ee only on module load, so
-	 * we may do drbd_release_ee only on module unload!
-	 */
+	clear_bit(AL_SUSPENDED, &mdev->flags);
+
 	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->tconn->sender_work.q));
 	D_ASSERT(list_empty(&mdev->resync_work.list));
 	D_ASSERT(list_empty(&mdev->unplug_work.list));
 	D_ASSERT(list_empty(&mdev->go_diskless.list));
@@ -3353,7 +2063,7 @@
 		goto Enomem;
 
 	drbd_ee_cache = kmem_cache_create(
-		"drbd_ee", sizeof(struct drbd_epoch_entry), 0, 0, NULL);
+		"drbd_ee", sizeof(struct drbd_peer_request), 0, 0, NULL);
 	if (drbd_ee_cache == NULL)
 		goto Enomem;
 
@@ -3368,11 +2078,9 @@
 		goto Enomem;
 
 	/* mempools */
-#ifdef COMPAT_HAVE_BIOSET_CREATE
 	drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0);
 	if (drbd_md_io_bio_set == NULL)
 		goto Enomem;
-#endif
 
 	drbd_md_io_page_pool = mempool_create_page_pool(DRBD_MIN_POOL_PAGES, 0);
 	if (drbd_md_io_page_pool == NULL)
@@ -3421,73 +2129,53 @@
 	.notifier_call = drbd_notify_sys,
 };
 
-static void drbd_release_ee_lists(struct drbd_conf *mdev)
+static void drbd_release_all_peer_reqs(struct drbd_conf *mdev)
 {
 	int rr;
 
-	rr = drbd_release_ee(mdev, &mdev->active_ee);
+	rr = drbd_free_peer_reqs(mdev, &mdev->active_ee);
 	if (rr)
 		dev_err(DEV, "%d EEs in active list found!\n", rr);
 
-	rr = drbd_release_ee(mdev, &mdev->sync_ee);
+	rr = drbd_free_peer_reqs(mdev, &mdev->sync_ee);
 	if (rr)
 		dev_err(DEV, "%d EEs in sync list found!\n", rr);
 
-	rr = drbd_release_ee(mdev, &mdev->read_ee);
+	rr = drbd_free_peer_reqs(mdev, &mdev->read_ee);
 	if (rr)
 		dev_err(DEV, "%d EEs in read list found!\n", rr);
 
-	rr = drbd_release_ee(mdev, &mdev->done_ee);
+	rr = drbd_free_peer_reqs(mdev, &mdev->done_ee);
 	if (rr)
 		dev_err(DEV, "%d EEs in done list found!\n", rr);
 
-	rr = drbd_release_ee(mdev, &mdev->net_ee);
+	rr = drbd_free_peer_reqs(mdev, &mdev->net_ee);
 	if (rr)
 		dev_err(DEV, "%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)
+/* caution. no locking. */
+void drbd_minor_destroy(struct kref *kref)
 {
-	struct drbd_conf *mdev = minor_to_mdev(minor);
-
-	if (!mdev)
-		return;
+	struct drbd_conf *mdev = container_of(kref, struct drbd_conf, kref);
+	struct drbd_tconn *tconn = mdev->tconn;
 
 	del_timer_sync(&mdev->request_timer);
 
 	/* paranoia asserts */
-	if (mdev->open_cnt != 0)
-		dev_err(DEV, "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) {
-			dev_err(DEV, "lp = %p\n", lp);
-		}
-	};
+	D_ASSERT(mdev->open_cnt == 0);
 	/* 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_free_bc(mdev->ldev);
+	mdev->ldev = NULL;
 
-	drbd_release_ee_lists(mdev);
-
-	/* should be freed on disconnect? */
-	kfree(mdev->ee_hash);
-	/*
-	mdev->ee_hash_s = 0;
-	mdev->ee_hash = NULL;
-	*/
+	drbd_release_all_peer_reqs(mdev);
 
 	lc_destroy(mdev->act_log);
 	lc_destroy(mdev->resync);
@@ -3495,19 +2183,101 @@
 	kfree(mdev->p_uuid);
 	/* mdev->p_uuid = NULL; */
 
-	kfree(mdev->int_dig_out);
-	kfree(mdev->int_dig_in);
-	kfree(mdev->int_dig_vv);
+	if (mdev->bitmap) /* should no longer be there. */
+		drbd_bm_cleanup(mdev);
+	__free_page(mdev->md_io_page);
+	put_disk(mdev->vdisk);
+	blk_cleanup_queue(mdev->rq_queue);
+	kfree(mdev->rs_plan_s);
+	kfree(mdev);
 
-	/* cleanup the rest that has been
-	 * allocated from drbd_new_device
-	 * and actually free the mdev itself */
-	drbd_free_mdev(mdev);
+	kref_put(&tconn->kref, &conn_destroy);
 }
 
+/* One global retry thread, if we need to push back some bio and have it
+ * reinserted through our make request function.
+ */
+static struct retry_worker {
+	struct workqueue_struct *wq;
+	struct work_struct worker;
+
+	spinlock_t lock;
+	struct list_head writes;
+} retry;
+
+static void do_retry(struct work_struct *ws)
+{
+	struct retry_worker *retry = container_of(ws, struct retry_worker, worker);
+	LIST_HEAD(writes);
+	struct drbd_request *req, *tmp;
+
+	spin_lock_irq(&retry->lock);
+	list_splice_init(&retry->writes, &writes);
+	spin_unlock_irq(&retry->lock);
+
+	list_for_each_entry_safe(req, tmp, &writes, tl_requests) {
+		struct drbd_conf *mdev = req->w.mdev;
+		struct bio *bio = req->master_bio;
+		unsigned long start_time = req->start_time;
+		bool expected;
+
+		expected = 
+			expect(atomic_read(&req->completion_ref) == 0) &&
+			expect(req->rq_state & RQ_POSTPONED) &&
+			expect((req->rq_state & RQ_LOCAL_PENDING) == 0 ||
+				(req->rq_state & RQ_LOCAL_ABORTED) != 0);
+
+		if (!expected)
+			dev_err(DEV, "req=%p completion_ref=%d rq_state=%x\n",
+				req, atomic_read(&req->completion_ref),
+				req->rq_state);
+
+		/* We still need to put one kref associated with the
+		 * "completion_ref" going zero in the code path that queued it
+		 * here.  The request object may still be referenced by a
+		 * frozen local req->private_bio, in case we force-detached.
+		 */
+		kref_put(&req->kref, drbd_req_destroy);
+
+		/* A single suspended or otherwise blocking device may stall
+		 * all others as well.  Fortunately, this code path is to
+		 * recover from a situation that "should not happen":
+		 * concurrent writes in multi-primary setup.
+		 * In a "normal" lifecycle, this workqueue is supposed to be
+		 * destroyed without ever doing anything.
+		 * If it turns out to be an issue anyways, we can do per
+		 * resource (replication group) or per device (minor) retry
+		 * workqueues instead.
+		 */
+
+		/* We are not just doing generic_make_request(),
+		 * as we want to keep the start_time information. */
+		inc_ap_bio(mdev);
+		__drbd_make_request(mdev, bio, start_time);
+	}
+}
+
+void drbd_restart_request(struct drbd_request *req)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&retry.lock, flags);
+	list_move_tail(&req->tl_requests, &retry.writes);
+	spin_unlock_irqrestore(&retry.lock, flags);
+
+	/* Drop the extra reference that would otherwise
+	 * have been dropped by complete_master_bio.
+	 * do_retry() needs to grab a new one. */
+	dec_ap_bio(req->w.mdev);
+
+	queue_work(retry.wq, &retry.worker);
+}
+
+
 static void drbd_cleanup(void)
 {
 	unsigned int i;
+	struct drbd_conf *mdev;
+	struct drbd_tconn *tconn, *tmp;
 
 	unregister_reboot_notifier(&drbd_notifier);
 
@@ -3522,19 +2292,31 @@
 	if (drbd_proc)
 		remove_proc_entry("drbd", NULL);
 
-	drbd_nl_cleanup();
+	if (retry.wq)
+		destroy_workqueue(retry.wq);
 
-	if (minor_table) {
-		i = minor_count;
-		while (i--)
-			drbd_delete_device(i);
-		drbd_destroy_mempools();
+	drbd_genl_unregister();
+
+	idr_for_each_entry(&minors, mdev, i) {
+		idr_remove(&minors, mdev_to_minor(mdev));
+		idr_remove(&mdev->tconn->volumes, mdev->vnr);
+		del_gendisk(mdev->vdisk);
+		/* synchronize_rcu(); No other threads running at this point */
+		kref_put(&mdev->kref, &drbd_minor_destroy);
 	}
 
-	kfree(minor_table);
+	/* not _rcu since, no other updater anymore. Genl already unregistered */
+	list_for_each_entry_safe(tconn, tmp, &drbd_tconns, all_tconn) {
+		list_del(&tconn->all_tconn); /* not _rcu no proc, not other threads */
+		/* synchronize_rcu(); */
+		kref_put(&tconn->kref, &conn_destroy);
+	}
 
+	drbd_destroy_mempools();
 	unregister_blkdev(DRBD_MAJOR, "drbd");
 
+	idr_destroy(&minors);
+
 	printk(KERN_INFO "drbd: module cleanup done.\n");
 }
 
@@ -3559,7 +2341,7 @@
 		goto out;
 	}
 
-	if (drbd_test_flag(mdev, CALLBACK_PENDING)) {
+	if (test_bit(CALLBACK_PENDING, &mdev->tconn->flags)) {
 		r |= (1 << BDI_async_congested);
 		/* Without good local data, we would need to read from remote,
 		 * and that would need the worker thread as well, which is
@@ -3583,7 +2365,7 @@
 			reason = 'b';
 	}
 
-	if (bdi_bits & (1 << BDI_async_congested) && drbd_test_flag(mdev, NET_CONGESTED)) {
+	if (bdi_bits & (1 << BDI_async_congested) && test_bit(NET_CONGESTED, &mdev->tconn->flags)) {
 		r |= (1 << BDI_async_congested);
 		reason = reason == 'b' ? 'a' : 'n';
 	}
@@ -3593,20 +2375,243 @@
 	return r;
 }
 
-struct drbd_conf *drbd_new_device(unsigned int minor)
+static void drbd_init_workqueue(struct drbd_work_queue* wq)
+{
+	spin_lock_init(&wq->q_lock);
+	INIT_LIST_HEAD(&wq->q);
+	init_waitqueue_head(&wq->q_wait);
+}
+
+struct drbd_tconn *conn_get_by_name(const char *name)
+{
+	struct drbd_tconn *tconn;
+
+	if (!name || !name[0])
+		return NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(tconn, &drbd_tconns, all_tconn) {
+		if (!strcmp(tconn->name, name)) {
+			kref_get(&tconn->kref);
+			goto found;
+		}
+	}
+	tconn = NULL;
+found:
+	rcu_read_unlock();
+	return tconn;
+}
+
+struct drbd_tconn *conn_get_by_addrs(void *my_addr, int my_addr_len,
+				     void *peer_addr, int peer_addr_len)
+{
+	struct drbd_tconn *tconn;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(tconn, &drbd_tconns, all_tconn) {
+		if (tconn->my_addr_len == my_addr_len &&
+		    tconn->peer_addr_len == peer_addr_len &&
+		    !memcmp(&tconn->my_addr, my_addr, my_addr_len) &&
+		    !memcmp(&tconn->peer_addr, peer_addr, peer_addr_len)) {
+			kref_get(&tconn->kref);
+			goto found;
+		}
+	}
+	tconn = NULL;
+found:
+	rcu_read_unlock();
+	return tconn;
+}
+
+static int drbd_alloc_socket(struct drbd_socket *socket)
+{
+	socket->rbuf = (void *) __get_free_page(GFP_KERNEL);
+	if (!socket->rbuf)
+		return -ENOMEM;
+	socket->sbuf = (void *) __get_free_page(GFP_KERNEL);
+	if (!socket->sbuf)
+		return -ENOMEM;
+	return 0;
+}
+
+static void drbd_free_socket(struct drbd_socket *socket)
+{
+	free_page((unsigned long) socket->sbuf);
+	free_page((unsigned long) socket->rbuf);
+}
+
+void conn_free_crypto(struct drbd_tconn *tconn)
+{
+	drbd_free_sock(tconn);
+
+	crypto_free_hash(tconn->csums_tfm);
+	crypto_free_hash(tconn->verify_tfm);
+	crypto_free_hash(tconn->cram_hmac_tfm);
+	crypto_free_hash(tconn->integrity_tfm);
+	crypto_free_hash(tconn->peer_integrity_tfm);
+	kfree(tconn->int_dig_in);
+	kfree(tconn->int_dig_vv);
+
+	tconn->csums_tfm = NULL;
+	tconn->verify_tfm = NULL;
+	tconn->cram_hmac_tfm = NULL;
+	tconn->integrity_tfm = NULL;
+	tconn->peer_integrity_tfm = NULL;
+	tconn->int_dig_in = NULL;
+	tconn->int_dig_vv = NULL;
+}
+
+int set_resource_options(struct drbd_tconn *tconn, struct res_opts *res_opts)
+{
+	cpumask_var_t new_cpu_mask;
+	int err;
+
+	if (!zalloc_cpumask_var(&new_cpu_mask, GFP_KERNEL))
+		return -ENOMEM;
+		/*
+		retcode = ERR_NOMEM;
+		drbd_msg_put_info("unable to allocate cpumask");
+		*/
+
+	/* silently ignore cpu mask on UP kernel */
+	if (nr_cpu_ids > 1 && res_opts->cpu_mask[0] != 0) {
+		/* FIXME: Get rid of constant 32 here */
+		err = bitmap_parse(res_opts->cpu_mask, 32,
+				   cpumask_bits(new_cpu_mask), nr_cpu_ids);
+		if (err) {
+			conn_warn(tconn, "bitmap_parse() failed with %d\n", err);
+			/* retcode = ERR_CPU_MASK_PARSE; */
+			goto fail;
+		}
+	}
+	tconn->res_opts = *res_opts;
+	if (!cpumask_equal(tconn->cpu_mask, new_cpu_mask)) {
+		cpumask_copy(tconn->cpu_mask, new_cpu_mask);
+		drbd_calc_cpu_mask(tconn);
+		tconn->receiver.reset_cpu_mask = 1;
+		tconn->asender.reset_cpu_mask = 1;
+		tconn->worker.reset_cpu_mask = 1;
+	}
+	err = 0;
+
+fail:
+	free_cpumask_var(new_cpu_mask);
+	return err;
+
+}
+
+/* caller must be under genl_lock() */
+struct drbd_tconn *conn_create(const char *name, struct res_opts *res_opts)
+{
+	struct drbd_tconn *tconn;
+
+	tconn = kzalloc(sizeof(struct drbd_tconn), GFP_KERNEL);
+	if (!tconn)
+		return NULL;
+
+	tconn->name = kstrdup(name, GFP_KERNEL);
+	if (!tconn->name)
+		goto fail;
+
+	if (drbd_alloc_socket(&tconn->data))
+		goto fail;
+	if (drbd_alloc_socket(&tconn->meta))
+		goto fail;
+
+	if (!zalloc_cpumask_var(&tconn->cpu_mask, GFP_KERNEL))
+		goto fail;
+
+	if (set_resource_options(tconn, res_opts))
+		goto fail;
+
+	tconn->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
+	if (!tconn->current_epoch)
+		goto fail;
+
+	INIT_LIST_HEAD(&tconn->transfer_log);
+
+	INIT_LIST_HEAD(&tconn->current_epoch->list);
+	tconn->epochs = 1;
+	spin_lock_init(&tconn->epoch_lock);
+	tconn->write_ordering = WO_bdev_flush;
+
+	tconn->send.seen_any_write_yet = false;
+	tconn->send.current_epoch_nr = 0;
+	tconn->send.current_epoch_writes = 0;
+
+	tconn->cstate = C_STANDALONE;
+	mutex_init(&tconn->cstate_mutex);
+	spin_lock_init(&tconn->req_lock);
+	mutex_init(&tconn->conf_update);
+	init_waitqueue_head(&tconn->ping_wait);
+	idr_init(&tconn->volumes);
+
+	drbd_init_workqueue(&tconn->sender_work);
+	mutex_init(&tconn->data.mutex);
+	mutex_init(&tconn->meta.mutex);
+
+	drbd_thread_init(tconn, &tconn->receiver, drbdd_init, "receiver");
+	drbd_thread_init(tconn, &tconn->worker, drbd_worker, "worker");
+	drbd_thread_init(tconn, &tconn->asender, drbd_asender, "asender");
+
+	kref_init(&tconn->kref);
+	list_add_tail_rcu(&tconn->all_tconn, &drbd_tconns);
+
+	return tconn;
+
+fail:
+	kfree(tconn->current_epoch);
+	free_cpumask_var(tconn->cpu_mask);
+	drbd_free_socket(&tconn->meta);
+	drbd_free_socket(&tconn->data);
+	kfree(tconn->name);
+	kfree(tconn);
+
+	return NULL;
+}
+
+void conn_destroy(struct kref *kref)
+{
+	struct drbd_tconn *tconn = container_of(kref, struct drbd_tconn, kref);
+
+	if (atomic_read(&tconn->current_epoch->epoch_size) !=  0)
+		conn_err(tconn, "epoch_size:%d\n", atomic_read(&tconn->current_epoch->epoch_size));
+	kfree(tconn->current_epoch);
+
+	idr_destroy(&tconn->volumes);
+
+	free_cpumask_var(tconn->cpu_mask);
+	drbd_free_socket(&tconn->meta);
+	drbd_free_socket(&tconn->data);
+	kfree(tconn->name);
+	kfree(tconn->int_dig_in);
+	kfree(tconn->int_dig_vv);
+	kfree(tconn);
+}
+
+enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor, int vnr)
 {
 	struct drbd_conf *mdev;
 	struct gendisk *disk;
 	struct request_queue *q;
+	int vnr_got = vnr;
+	int minor_got = minor;
+	enum drbd_ret_code err = ERR_NOMEM;
+
+	mdev = minor_to_mdev(minor);
+	if (mdev)
+		return ERR_MINOR_EXISTS;
 
 	/* GFP_KERNEL, we are outside of all write-out paths */
 	mdev = kzalloc(sizeof(struct drbd_conf), GFP_KERNEL);
 	if (!mdev)
-		return NULL;
-	if (!zalloc_cpumask_var(&mdev->cpu_mask, GFP_KERNEL))
-		goto out_no_cpumask;
+		return ERR_NOMEM;
+
+	kref_get(&tconn->kref);
+	mdev->tconn = tconn;
 
 	mdev->minor = minor;
+	mdev->vnr = vnr;
 
 	drbd_init_set_defaults(mdev);
 
@@ -3644,7 +2649,7 @@
 	blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE_SAFE >> 8);
 	blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
 	blk_queue_merge_bvec(q, drbd_merge_bvec);
-	q->queue_lock = &mdev->req_lock;
+	q->queue_lock = &mdev->tconn->req_lock; /* needed since we use */
 
 	mdev->md_io_page = alloc_page(GFP_KERNEL);
 	if (!mdev->md_io_page)
@@ -3652,30 +2657,44 @@
 
 	if (drbd_bm_init(mdev))
 		goto out_no_bitmap;
-	/* no need to lock access, we are still initializing this minor device. */
-	if (!tl_init(mdev))
-		goto out_no_tl;
+	mdev->read_requests = RB_ROOT;
+	mdev->write_requests = RB_ROOT;
 
-	mdev->app_reads_hash = kzalloc(APP_R_HSIZE*sizeof(void *), GFP_KERNEL);
-	if (!mdev->app_reads_hash)
-		goto out_no_app_reads;
+	if (!idr_pre_get(&minors, GFP_KERNEL))
+		goto out_no_minor_idr;
+	if (idr_get_new_above(&minors, mdev, minor, &minor_got))
+		goto out_no_minor_idr;
+	if (minor_got != minor) {
+		err = ERR_MINOR_EXISTS;
+		drbd_msg_put_info("requested minor exists already");
+		goto out_idr_remove_minor;
+	}
 
-	mdev->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
-	if (!mdev->current_epoch)
-		goto out_no_epoch;
+	if (!idr_pre_get(&tconn->volumes, GFP_KERNEL))
+		goto out_idr_remove_minor;
+	if (idr_get_new_above(&tconn->volumes, mdev, vnr, &vnr_got))
+		goto out_idr_remove_minor;
+	if (vnr_got != vnr) {
+		err = ERR_INVALID_REQUEST;
+		drbd_msg_put_info("requested volume exists already");
+		goto out_idr_remove_vol;
+	}
+	add_disk(disk);
+	kref_init(&mdev->kref); /* one ref for both idrs and the the add_disk */
 
-	INIT_LIST_HEAD(&mdev->current_epoch->list);
-	mdev->epochs = 1;
+	/* inherit the connection state */
+	mdev->state.conn = tconn->cstate;
+	if (mdev->state.conn == C_WF_REPORT_PARAMS)
+		drbd_connected(mdev);
 
-	return mdev;
+	return NO_ERROR;
 
-/* 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:
+out_idr_remove_vol:
+	idr_remove(&tconn->volumes, vnr_got);
+out_idr_remove_minor:
+	idr_remove(&minors, minor_got);
+	synchronize_rcu();
+out_no_minor_idr:
 	drbd_bm_cleanup(mdev);
 out_no_bitmap:
 	__free_page(mdev->md_io_page);
@@ -3684,55 +2703,25 @@
 out_no_disk:
 	blk_cleanup_queue(q);
 out_no_q:
-	free_cpumask_var(mdev->cpu_mask);
-out_no_cpumask:
 	kfree(mdev);
-	return NULL;
+	kref_put(&tconn->kref, &conn_destroy);
+	return err;
 }
 
-/* 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);
-	if (mdev->bitmap) /* should no longer be there. */
-		drbd_bm_cleanup(mdev);
-	__free_page(mdev->md_io_page);
-	put_disk(mdev->vdisk);
-	blk_cleanup_queue(mdev->rq_queue);
-	free_cpumask_var(mdev->cpu_mask);
-	drbd_free_tl_hash(mdev);
-	kfree(mdev);
-}
-
-
 int __init drbd_init(void)
 {
 	int err;
 
-	if (sizeof(struct p_handshake) != 80) {
-		printk(KERN_ERR
-		       "drbd: never change the size or layout "
-		       "of the HandShake packet.\n");
-		return -EINVAL;
-	}
-
 	if (minor_count < DRBD_MINOR_COUNT_MIN || minor_count > DRBD_MINOR_COUNT_MAX) {
 		printk(KERN_ERR
-			"drbd: invalid minor_count (%d)\n", minor_count);
+		       "drbd: invalid minor_count (%d)\n", minor_count);
 #ifdef MODULE
 		return -EINVAL;
 #else
-		minor_count = 8;
+		minor_count = DRBD_MINOR_COUNT_DEF;
 #endif
 	}
 
-	err = drbd_nl_init();
-	if (err)
-		return err;
-
 	err = register_blkdev(DRBD_MAJOR, "drbd");
 	if (err) {
 		printk(KERN_ERR
@@ -3741,6 +2730,13 @@
 		return err;
 	}
 
+	err = drbd_genl_register();
+	if (err) {
+		printk(KERN_ERR "drbd: unable to register generic netlink family\n");
+		goto fail;
+	}
+
+
 	register_reboot_notifier(&drbd_notifier);
 
 	/*
@@ -3751,22 +2747,29 @@
 	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;
+	idr_init(&minors);
 
 	err = drbd_create_mempools();
 	if (err)
-		goto Enomem;
+		goto fail;
 
 	drbd_proc = proc_create_data("drbd", S_IFREG | S_IRUGO , NULL, &drbd_proc_fops, NULL);
 	if (!drbd_proc)	{
 		printk(KERN_ERR "drbd: unable to register proc file\n");
-		goto Enomem;
+		goto fail;
 	}
 
 	rwlock_init(&global_state_lock);
+	INIT_LIST_HEAD(&drbd_tconns);
+
+	retry.wq = create_singlethread_workqueue("drbd-reissue");
+	if (!retry.wq) {
+		printk(KERN_ERR "drbd: unable to create retry workqueue\n");
+		goto fail;
+	}
+	INIT_WORK(&retry.worker, do_retry);
+	spin_lock_init(&retry.lock);
+	INIT_LIST_HEAD(&retry.writes);
 
 	printk(KERN_INFO "drbd: initialized. "
 	       "Version: " REL_VERSION " (api:%d/proto:%d-%d)\n",
@@ -3774,11 +2777,10 @@
 	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:
+fail:
 	drbd_cleanup();
 	if (err == -ENOMEM)
 		/* currently always the case */
@@ -3799,47 +2801,42 @@
 	kfree(ldev);
 }
 
-void drbd_free_sock(struct drbd_conf *mdev)
+void drbd_free_sock(struct drbd_tconn *tconn)
 {
-	if (mdev->data.socket) {
-		mutex_lock(&mdev->data.mutex);
-		kernel_sock_shutdown(mdev->data.socket, SHUT_RDWR);
-		sock_release(mdev->data.socket);
-		mdev->data.socket = NULL;
-		mutex_unlock(&mdev->data.mutex);
+	if (tconn->data.socket) {
+		mutex_lock(&tconn->data.mutex);
+		kernel_sock_shutdown(tconn->data.socket, SHUT_RDWR);
+		sock_release(tconn->data.socket);
+		tconn->data.socket = NULL;
+		mutex_unlock(&tconn->data.mutex);
 	}
-	if (mdev->meta.socket) {
-		mutex_lock(&mdev->meta.mutex);
-		kernel_sock_shutdown(mdev->meta.socket, SHUT_RDWR);
-		sock_release(mdev->meta.socket);
-		mdev->meta.socket = NULL;
-		mutex_unlock(&mdev->meta.mutex);
+	if (tconn->meta.socket) {
+		mutex_lock(&tconn->meta.mutex);
+		kernel_sock_shutdown(tconn->meta.socket, SHUT_RDWR);
+		sock_release(tconn->meta.socket);
+		tconn->meta.socket = NULL;
+		mutex_unlock(&tconn->meta.mutex);
 	}
 }
 
-
-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->ldev);
-		  mdev->ldev = NULL;);
-}
-
 /* meta data management */
 
+void conn_md_sync(struct drbd_tconn *tconn)
+{
+	struct drbd_conf *mdev;
+	int vnr;
+
+	rcu_read_lock();
+	idr_for_each_entry(&tconn->volumes, mdev, vnr) {
+		kref_get(&mdev->kref);
+		rcu_read_unlock();
+		drbd_md_sync(mdev);
+		kref_put(&mdev->kref, &drbd_minor_destroy);
+		rcu_read_lock();
+	}
+	rcu_read_unlock();
+}
+
 struct meta_data_on_disk {
 	u64 la_size;           /* last agreed size. */
 	u64 uuid[UI_SIZE];   /* UUIDs. */
@@ -3850,7 +2847,7 @@
 	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 */
+	      /* `-- act_log->nr_elements <-- ldev->dc.al_extents */
 	u32 bm_offset;         /* offset to the bitmap, from here */
 	u32 bm_bytes_per_bit;  /* BM_BLOCK_SIZE */
 	u32 la_peer_max_bio_size;   /* last peer max_bio_size */
@@ -3870,7 +2867,7 @@
 
 	del_timer(&mdev->md_sync_timer);
 	/* timer may be rearmed by drbd_md_mark_dirty() now. */
-	if (!drbd_test_and_clear_flag(mdev, MD_DIRTY))
+	if (!test_and_clear_bit(MD_DIRTY, &mdev->flags))
 		return;
 
 	/* We use here D_FAILED and not D_ATTACHING because we try to write
@@ -3888,7 +2885,7 @@
 	for (i = UI_CURRENT; i < UI_SIZE; i++)
 		buffer->uuid[i] = cpu_to_be64(mdev->ldev->md.uuid[i]);
 	buffer->flags = cpu_to_be32(mdev->ldev->md.flags);
-	buffer->magic = cpu_to_be32(DRBD_MD_MAGIC);
+	buffer->magic = cpu_to_be32(DRBD_MD_MAGIC_84_UNCLEAN);
 
 	buffer->md_size_sect  = cpu_to_be32(mdev->ldev->md.md_size_sect);
 	buffer->al_offset     = cpu_to_be32(mdev->ldev->md.al_offset);
@@ -3902,7 +2899,7 @@
 	D_ASSERT(drbd_md_ss__(mdev, mdev->ldev) == mdev->ldev->md.md_offset);
 	sector = mdev->ldev->md.md_offset;
 
-	if (!drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)) {
+	if (drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)) {
 		/* this was a try anyways ... */
 		dev_err(DEV, "meta data update failed!\n");
 		drbd_chk_io_error(mdev, 1, DRBD_META_IO_ERROR);
@@ -3923,11 +2920,12 @@
  * @bdev:	Device from which the meta data should be read in.
  *
  * Return 0 (NO_ERROR) on success, and an enum drbd_ret_code in case
- * something goes wrong.  Currently only: ERR_IO_MD_DISK, ERR_MD_INVALID.
+ * something goes wrong.
  */
 int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 {
 	struct meta_data_on_disk *buffer;
+	u32 magic, flags;
 	int i, rv = NO_ERROR;
 
 	if (!get_ldev_if_state(mdev, D_ATTACHING))
@@ -3937,7 +2935,7 @@
 	if (!buffer)
 		goto out;
 
-	if (!drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
+	if (drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
 		/* NOTE: can't do normal error processing here as this is
 		   called BEFORE disk is attached */
 		dev_err(DEV, "Error while reading metadata.\n");
@@ -3945,8 +2943,20 @@
 		goto err;
 	}
 
-	if (be32_to_cpu(buffer->magic) != DRBD_MD_MAGIC) {
-		dev_err(DEV, "Error while reading metadata, magic not found.\n");
+	magic = be32_to_cpu(buffer->magic);
+	flags = be32_to_cpu(buffer->flags);
+	if (magic == DRBD_MD_MAGIC_84_UNCLEAN ||
+	    (magic == DRBD_MD_MAGIC_08 && !(flags & MDF_AL_CLEAN))) {
+			/* btw: that's Activity Log clean, not "all" clean. */
+		dev_err(DEV, "Found unclean meta data. Did you \"drbdadm apply-al\"?\n");
+		rv = ERR_MD_UNCLEAN;
+		goto err;
+	}
+	if (magic != DRBD_MD_MAGIC_08) {
+		if (magic == DRBD_MD_MAGIC_07)
+			dev_err(DEV, "Found old (0.7) meta data magic. Did you \"drbdadm create-md\"?\n");
+		else
+			dev_err(DEV, "Meta data magic not found. Did you \"drbdadm create-md\"?\n");
 		rv = ERR_MD_INVALID;
 		goto err;
 	}
@@ -3980,20 +2990,16 @@
 	for (i = UI_CURRENT; i < UI_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);
 
-	spin_lock_irq(&mdev->req_lock);
+	spin_lock_irq(&mdev->tconn->req_lock);
 	if (mdev->state.conn < C_CONNECTED) {
 		unsigned int peer;
 		peer = be32_to_cpu(buffer->la_peer_max_bio_size);
 		peer = max(peer, DRBD_MAX_BIO_SIZE_SAFE);
 		mdev->peer_max_bio_size = peer;
 	}
-	spin_unlock_irq(&mdev->req_lock);
-
-	if (mdev->sync_conf.al_extents < 7)
-		mdev->sync_conf.al_extents = 127;
+	spin_unlock_irq(&mdev->tconn->req_lock);
 
  err:
 	drbd_md_put_buffer(mdev);
@@ -4014,7 +3020,7 @@
 #ifdef DEBUG
 void drbd_md_mark_dirty_(struct drbd_conf *mdev, unsigned int line, const char *func)
 {
-	if (!drbd_test_and_set_flag(mdev, MD_DIRTY)) {
+	if (!test_and_set_bit(MD_DIRTY, &mdev->flags)) {
 		mod_timer(&mdev->md_sync_timer, jiffies + HZ);
 		mdev->last_md_mark_dirty.line = line;
 		mdev->last_md_mark_dirty.func = func;
@@ -4023,7 +3029,7 @@
 #else
 void drbd_md_mark_dirty(struct drbd_conf *mdev)
 {
-	if (!drbd_test_and_set_flag(mdev, MD_DIRTY))
+	if (!test_and_set_bit(MD_DIRTY, &mdev->flags))
 		mod_timer(&mdev->md_sync_timer, jiffies + 5*HZ);
 }
 #endif
@@ -4171,9 +3177,10 @@
 	return rv;
 }
 
-static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+static int w_bitmap_io(struct drbd_work *w, int unused)
 {
 	struct bm_io_work *work = container_of(w, struct bm_io_work, w);
+	struct drbd_conf *mdev = w->mdev;
 	int rv = -EIO;
 
 	D_ASSERT(atomic_read(&mdev->ap_bio_cnt) == 0);
@@ -4185,18 +3192,17 @@
 		put_ldev(mdev);
 	}
 
-	drbd_clear_flag(mdev, BITMAP_IO);
-	smp_mb__after_clear_bit();
+	clear_bit_unlock(BITMAP_IO, &mdev->flags);
 	wake_up(&mdev->misc_wait);
 
 	if (work->done)
 		work->done(mdev, rv);
 
-	drbd_clear_flag(mdev, BITMAP_IO_QUEUED);
+	clear_bit(BITMAP_IO_QUEUED, &mdev->flags);
 	work->why = NULL;
 	work->flags = 0;
 
-	return 1;
+	return 0;
 }
 
 void drbd_ldev_destroy(struct drbd_conf *mdev)
@@ -4209,15 +3215,13 @@
 		drbd_free_bc(mdev->ldev);
 		mdev->ldev = NULL;);
 
-	if (mdev->md_io_tmpp) {
-		__free_page(mdev->md_io_tmpp);
-		mdev->md_io_tmpp = NULL;
-	}
-	drbd_clear_flag(mdev, GO_DISKLESS);
+	clear_bit(GO_DISKLESS, &mdev->flags);
 }
 
-static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+static int w_go_diskless(struct drbd_work *w, int unused)
 {
+	struct drbd_conf *mdev = w->mdev;
+
 	D_ASSERT(mdev->state.disk == D_FAILED);
 	/* we cannot assert local_cnt == 0 here, as get_ldev_if_state will
 	 * inc/dec it frequently. Once we are D_DISKLESS, no one will touch
@@ -4232,11 +3236,15 @@
 	 * (Do we want a specific meta data flag for this?)
 	 *
 	 * If that does not make it to stable storage either,
-	 * we cannot do anything about that anymore.  */
-	if (mdev->bitmap) {
+	 * we cannot do anything about that anymore.
+	 *
+	 * We still need to check if both bitmap and ldev are present, we may
+	 * end up here after a failed attach, before ldev was even assigned.
+	 */
+	if (mdev->bitmap && mdev->ldev) {
 		if (drbd_bitmap_io_from_worker(mdev, drbd_bm_write,
 					"detach", BM_LOCKED_MASK)) {
-			if (drbd_test_flag(mdev, WAS_READ_ERROR)) {
+			if (test_bit(WAS_READ_ERROR, &mdev->flags)) {
 				drbd_md_set_flag(mdev, MDF_FULL_SYNC);
 				drbd_md_sync(mdev);
 			}
@@ -4244,14 +3252,14 @@
 	}
 
 	drbd_force_state(mdev, NS(disk, D_DISKLESS));
-	return 1;
+	return 0;
 }
 
 void drbd_go_diskless(struct drbd_conf *mdev)
 {
 	D_ASSERT(mdev->state.disk == D_FAILED);
-	if (!drbd_test_and_set_flag(mdev, GO_DISKLESS))
-		drbd_queue_work(&mdev->data.work, &mdev->go_diskless);
+	if (!test_and_set_bit(GO_DISKLESS, &mdev->flags))
+		drbd_queue_work(&mdev->tconn->sender_work, &mdev->go_diskless);
 }
 
 /**
@@ -4271,10 +3279,10 @@
 			  void (*done)(struct drbd_conf *, int),
 			  char *why, enum bm_flag flags)
 {
-	D_ASSERT(current == mdev->worker.task);
+	D_ASSERT(current == mdev->tconn->worker.task);
 
-	D_ASSERT(!drbd_test_flag(mdev, BITMAP_IO_QUEUED));
-	D_ASSERT(!drbd_test_flag(mdev, BITMAP_IO));
+	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)
 		dev_err(DEV, "FIXME going to queue '%s' but '%s' still pending?\n",
@@ -4285,13 +3293,13 @@
 	mdev->bm_io_work.why = why;
 	mdev->bm_io_work.flags = flags;
 
-	spin_lock_irq(&mdev->req_lock);
-	drbd_set_flag(mdev, BITMAP_IO);
+	spin_lock_irq(&mdev->tconn->req_lock);
+	set_bit(BITMAP_IO, &mdev->flags);
 	if (atomic_read(&mdev->ap_bio_cnt) == 0) {
-		if (!drbd_test_and_set_flag(mdev, BITMAP_IO_QUEUED))
-			drbd_queue_work(&mdev->data.work, &mdev->bm_io_work.w);
+		if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
+			drbd_queue_work(&mdev->tconn->sender_work, &mdev->bm_io_work.w);
 	}
-	spin_unlock_irq(&mdev->req_lock);
+	spin_unlock_irq(&mdev->tconn->req_lock);
 }
 
 /**
@@ -4308,7 +3316,7 @@
 {
 	int rv;
 
-	D_ASSERT(current != mdev->worker.task);
+	D_ASSERT(current != mdev->tconn->worker.task);
 
 	if ((flags & BM_LOCKED_SET_ALLOWED) == 0)
 		drbd_suspend_io(mdev);
@@ -4347,18 +3355,127 @@
 {
 	struct drbd_conf *mdev = (struct drbd_conf *) data;
 
-	drbd_queue_work_front(&mdev->data.work, &mdev->md_sync_work);
+	/* must not double-queue! */
+	if (list_empty(&mdev->md_sync_work.list))
+		drbd_queue_work_front(&mdev->tconn->sender_work, &mdev->md_sync_work);
 }
 
-static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+static int w_md_sync(struct drbd_work *w, int unused)
 {
+	struct drbd_conf *mdev = w->mdev;
+
 	dev_warn(DEV, "md_sync_timer expired! Worker calls drbd_md_sync().\n");
 #ifdef DEBUG
 	dev_warn(DEV, "last md_mark_dirty: %s:%u\n",
 		mdev->last_md_mark_dirty.func, mdev->last_md_mark_dirty.line);
 #endif
 	drbd_md_sync(mdev);
-	return 1;
+	return 0;
+}
+
+const char *cmdname(enum drbd_packet cmd)
+{
+	/* THINK may need to become several global tables
+	 * when we want to support more than
+	 * one PRO_VERSION */
+	static const char *cmdnames[] = {
+		[P_DATA]	        = "Data",
+		[P_DATA_REPLY]	        = "DataReply",
+		[P_RS_DATA_REPLY]	= "RSDataReply",
+		[P_BARRIER]	        = "Barrier",
+		[P_BITMAP]	        = "ReportBitMap",
+		[P_BECOME_SYNC_TARGET]  = "BecomeSyncTarget",
+		[P_BECOME_SYNC_SOURCE]  = "BecomeSyncSource",
+		[P_UNPLUG_REMOTE]	= "UnplugRemote",
+		[P_DATA_REQUEST]	= "DataRequest",
+		[P_RS_DATA_REQUEST]     = "RSDataRequest",
+		[P_SYNC_PARAM]	        = "SyncParam",
+		[P_SYNC_PARAM89]	= "SyncParam89",
+		[P_PROTOCOL]            = "ReportProtocol",
+		[P_UUIDS]	        = "ReportUUIDs",
+		[P_SIZES]	        = "ReportSizes",
+		[P_STATE]	        = "ReportState",
+		[P_SYNC_UUID]           = "ReportSyncUUID",
+		[P_AUTH_CHALLENGE]      = "AuthChallenge",
+		[P_AUTH_RESPONSE]	= "AuthResponse",
+		[P_PING]		= "Ping",
+		[P_PING_ACK]	        = "PingAck",
+		[P_RECV_ACK]	        = "RecvAck",
+		[P_WRITE_ACK]	        = "WriteAck",
+		[P_RS_WRITE_ACK]	= "RSWriteAck",
+		[P_SUPERSEDED]          = "Superseded",
+		[P_NEG_ACK]	        = "NegAck",
+		[P_NEG_DREPLY]	        = "NegDReply",
+		[P_NEG_RS_DREPLY]	= "NegRSDReply",
+		[P_BARRIER_ACK]	        = "BarrierAck",
+		[P_STATE_CHG_REQ]       = "StateChgRequest",
+		[P_STATE_CHG_REPLY]     = "StateChgReply",
+		[P_OV_REQUEST]          = "OVRequest",
+		[P_OV_REPLY]            = "OVReply",
+		[P_OV_RESULT]           = "OVResult",
+		[P_CSUM_RS_REQUEST]     = "CsumRSRequest",
+		[P_RS_IS_IN_SYNC]	= "CsumRSIsInSync",
+		[P_COMPRESSED_BITMAP]   = "CBitmap",
+		[P_DELAY_PROBE]         = "DelayProbe",
+		[P_OUT_OF_SYNC]		= "OutOfSync",
+		[P_RETRY_WRITE]		= "RetryWrite",
+		[P_RS_CANCEL]		= "RSCancel",
+		[P_CONN_ST_CHG_REQ]	= "conn_st_chg_req",
+		[P_CONN_ST_CHG_REPLY]	= "conn_st_chg_reply",
+		[P_RETRY_WRITE]		= "retry_write",
+		[P_PROTOCOL_UPDATE]	= "protocol_update",
+
+		/* enum drbd_packet, but not commands - obsoleted flags:
+		 *	P_MAY_IGNORE
+		 *	P_MAX_OPT_CMD
+		 */
+	};
+
+	/* too big for the array: 0xfffX */
+	if (cmd == P_INITIAL_META)
+		return "InitialMeta";
+	if (cmd == P_INITIAL_DATA)
+		return "InitialData";
+	if (cmd == P_CONNECTION_FEATURES)
+		return "ConnectionFeatures";
+	if (cmd >= ARRAY_SIZE(cmdnames))
+		return "Unknown";
+	return cmdnames[cmd];
+}
+
+/**
+ * drbd_wait_misc  -  wait for a request to make progress
+ * @mdev:	device associated with the request
+ * @i:		the struct drbd_interval embedded in struct drbd_request or
+ *		struct drbd_peer_request
+ */
+int drbd_wait_misc(struct drbd_conf *mdev, struct drbd_interval *i)
+{
+	struct net_conf *nc;
+	DEFINE_WAIT(wait);
+	long timeout;
+
+	rcu_read_lock();
+	nc = rcu_dereference(mdev->tconn->net_conf);
+	if (!nc) {
+		rcu_read_unlock();
+		return -ETIMEDOUT;
+	}
+	timeout = nc->ko_count ? nc->timeout * HZ / 10 * nc->ko_count : MAX_SCHEDULE_TIMEOUT;
+	rcu_read_unlock();
+
+	/* Indicate to wake up mdev->misc_wait on progress.  */
+	i->waiting = true;
+	prepare_to_wait(&mdev->misc_wait, &wait, TASK_INTERRUPTIBLE);
+	spin_unlock_irq(&mdev->tconn->req_lock);
+	timeout = schedule_timeout(timeout);
+	finish_wait(&mdev->misc_wait, &wait);
+	spin_lock_irq(&mdev->tconn->req_lock);
+	if (!timeout || mdev->state.conn < C_CONNECTED)
+		return -ETIMEDOUT;
+	if (signal_pending(current))
+		return -ERESTARTSYS;
+	return 0;
 }
 
 #ifdef CONFIG_DRBD_FAULT_INJECTION