Merge branch 'for-2.6.40/drivers' of git://git.kernel.dk/linux-2.6-block

* 'for-2.6.40/drivers' of git://git.kernel.dk/linux-2.6-block: (110 commits)
  loop: handle on-demand devices correctly
  loop: limit 'max_part' module param to DISK_MAX_PARTS
  drbd: fix warning
  drbd: fix warning
  drbd: Fix spelling
  drbd: fix schedule in atomic
  drbd: Take a more conservative approach when deciding max_bio_size
  drbd: Fixed state transitions after async outdate-peer-handler returned
  drbd: Disallow the peer_disk_state to be D_OUTDATED while connected
  drbd: Fix for the connection problems on high latency links
  drbd: fix potential activity log refcount imbalance in error path
  drbd: Only downgrade the disk state in case of disk failures
  drbd: fix disconnect/reconnect loop, if ping-timeout == ping-int
  drbd: fix potential distributed deadlock
  lru_cache.h: fix comments referring to ts_ instead of lc_
  drbd: Fix for application IO with the on-io-error=pass-on policy
  xen/p2m: Add EXPORT_SYMBOL_GPL to the M2P override functions.
  xen/p2m/m2p/gnttab: Support GNTMAP_host_map in the M2P override.
  xen/blkback: don't fail empty barrier requests
  xen/blkback: fix xenbus_transaction_start() hang caused by double xenbus_transaction_end()
  ...

9 files changed, 243 insertions, 139 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index c6828b68d77b..09ef9a878ef0 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -28,7 +28,7 @@
 #include "drbd_int.h"
 #include "drbd_wrappers.h"
 
-/* We maintain a trivial check sum in our on disk activity log.
+/* We maintain a trivial checksum in our on disk activity log.
  * With that we can ensure correct operation even when the storage
  * device might do a partial (last) sector write while losing power.
  */
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index 76210ba401ac..f440a02dfdb1 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -74,7 +74,7 @@
  *	as we are "attached" to a local disk, which at 32 GiB for 1PiB storage
  *	seems excessive.
  *
- *	We plan to reduce the amount of in-core bitmap pages by pageing them in
+ *	We plan to reduce the amount of in-core bitmap pages by paging them in
  *	and out against their on-disk location as necessary, but need to make
  *	sure we don't cause too much meta data IO, and must not deadlock in
  *	tight memory situations. This needs some more work.
@@ -200,7 +200,7 @@ void drbd_bm_unlock(struct drbd_conf *mdev)
  * we if bits have been cleared since last IO. */
 #define BM_PAGE_LAZY_WRITEOUT	28
 
-/* store_page_idx uses non-atomic assingment. It is only used directly after
+/* store_page_idx uses non-atomic assignment. It is only used directly after
  * allocating the page.  All other bm_set_page_* and bm_clear_page_* need to
  * use atomic bit manipulation, as set_out_of_sync (and therefore bitmap
  * changes) may happen from various contexts, and wait_on_bit/wake_up_bit
@@ -318,7 +318,7 @@ static void bm_unmap(unsigned long *p_addr)
 /* word offset from start of bitmap to word number _in_page_
  * modulo longs per page
 #define MLPP(X) ((X) % (PAGE_SIZE/sizeof(long))
- hm, well, Philipp thinks gcc might not optimze the % into & (... - 1)
+ hm, well, Philipp thinks gcc might not optimize the % into & (... - 1)
  so do it explicitly:
  */
 #define MLPP(X) ((X) & ((PAGE_SIZE/sizeof(long))-1))
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index d871b14ed5a1..ef2ceed3be4b 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -700,7 +700,7 @@ struct drbd_request {
 	 * see drbd_endio_pri(). */
 	struct bio *private_bio;
 
-	struct hlist_node colision;
+	struct hlist_node collision;
 	sector_t sector;
 	unsigned int size;
 	unsigned int epoch; /* barrier_nr */
@@ -766,7 +766,7 @@ struct digest_info {
 
 struct drbd_epoch_entry {
 	struct drbd_work w;
-	struct hlist_node colision;
+	struct hlist_node collision;
 	struct drbd_epoch *epoch; /* for writes */
 	struct drbd_conf *mdev;
 	struct page *pages;
@@ -1129,6 +1129,8 @@ struct drbd_conf {
 	int rs_in_flight; /* resync sectors in flight (to proxy, in proxy and from proxy) */
 	int rs_planed;    /* resync sectors already planned */
 	atomic_t ap_in_flight; /* App sectors in flight (waiting for ack) */
+	int peer_max_bio_size;
+	int local_max_bio_size;
 };
 
 static inline struct drbd_conf *minor_to_mdev(unsigned int minor)
@@ -1218,8 +1220,6 @@ extern void drbd_free_resources(struct drbd_conf *mdev);
 extern void tl_release(struct drbd_conf *mdev, unsigned int barrier_nr,
 		       unsigned int set_size);
 extern void tl_clear(struct drbd_conf *mdev);
-enum drbd_req_event;
-extern void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what);
 extern void _tl_add_barrier(struct drbd_conf *, struct drbd_tl_epoch *);
 extern void drbd_free_sock(struct drbd_conf *mdev);
 extern int drbd_send(struct drbd_conf *mdev, struct socket *sock,
@@ -1434,6 +1434,7 @@ struct bm_extent {
  * hash table. */
 #define HT_SHIFT 8
 #define DRBD_MAX_BIO_SIZE (1U<<(9+HT_SHIFT))
+#define DRBD_MAX_BIO_SIZE_SAFE (1 << 12)       /* Works always = 4k */
 
 #define DRBD_MAX_SIZE_H80_PACKET (1 << 15) /* The old header only allows packets up to 32Kib data */
 
@@ -1518,9 +1519,9 @@ extern void drbd_resume_io(struct drbd_conf *mdev);
 extern char *ppsize(char *buf, unsigned long long size);
 extern sector_t drbd_new_dev_size(struct drbd_conf *, struct drbd_backing_dev *, int);
 enum determine_dev_size { dev_size_error = -1, unchanged = 0, shrunk = 1, grew = 2 };
-extern enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *, enum dds_flags) __must_hold(local);
+extern enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *, enum dds_flags) __must_hold(local);
 extern void resync_after_online_grow(struct drbd_conf *);
-extern void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int) __must_hold(local);
+extern void drbd_reconsider_max_bio_size(struct drbd_conf *mdev);
 extern enum drbd_state_rv drbd_set_role(struct drbd_conf *mdev,
 					enum drbd_role new_role,
 					int force);
@@ -1828,6 +1829,8 @@ static inline void __drbd_chk_io_error_(struct drbd_conf *mdev, int forcedetach,
 		if (!forcedetach) {
 			if (__ratelimit(&drbd_ratelimit_state))
 				dev_err(DEV, "Local IO failed in %s.\n", where);
+			if (mdev->state.disk > D_INCONSISTENT)
+				_drbd_set_state(_NS(mdev, disk, D_INCONSISTENT), CS_HARD, NULL);
 			break;
 		}
 		/* NOTE fall through to detach case if forcedetach set */
@@ -2153,6 +2156,10 @@ static inline int get_net_conf(struct drbd_conf *mdev)
 static inline void put_ldev(struct drbd_conf *mdev)
 {
 	int i = atomic_dec_return(&mdev->local_cnt);
+
+	/* This may be called from some endio handler,
+	 * so we must not sleep here. */
+
 	__release(local);
 	D_ASSERT(i >= 0);
 	if (i == 0) {
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 5b525c179f39..0358e55356c8 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -745,6 +745,9 @@ is_valid_state(struct drbd_conf *mdev, union drbd_state ns)
 		  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;
 }
 
@@ -1565,6 +1568,10 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
 		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)
+		drbd_send_state(mdev);
+
 	/* Disks got bigger while they were detached */
 	if (ns.disk > D_NEGOTIATING && ns.pdsk > D_NEGOTIATING &&
 	    test_and_clear_bit(RESYNC_AFTER_NEG, &mdev->flags)) {
@@ -2064,7 +2071,7 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
 {
 	struct p_sizes p;
 	sector_t d_size, u_size;
-	int q_order_type;
+	int q_order_type, max_bio_size;
 	int ok;
 
 	if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
@@ -2072,17 +2079,20 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
 		d_size = drbd_get_max_capacity(mdev->ldev);
 		u_size = mdev->ldev->dc.disk_size;
 		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_t(int, max_bio_size, DRBD_MAX_BIO_SIZE);
 		put_ldev(mdev);
 	} else {
 		d_size = 0;
 		u_size = 0;
 		q_order_type = QUEUE_ORDERED_NONE;
+		max_bio_size = DRBD_MAX_BIO_SIZE; /* ... multiple BIOs per peer_request */
 	}
 
 	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(queue_max_hw_sectors(mdev->rq_queue) << 9);
+	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);
 
@@ -2722,7 +2732,7 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
 
 		/* double check digest, sometimes buffers have been modified in flight. */
 		if (dgs > 0 && dgs <= 64) {
-			/* 64 byte, 512 bit, is the larges digest size
+			/* 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);
@@ -3041,6 +3051,8 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
 	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;
 }
 
 void drbd_mdev_cleanup(struct drbd_conf *mdev)
@@ -3275,7 +3287,7 @@ static void drbd_delete_device(unsigned int minor)
 
 	drbd_release_ee_lists(mdev);
 
-	/* should be free'd on disconnect? */
+	/* should be freed on disconnect? */
 	kfree(mdev->ee_hash);
 	/*
 	mdev->ee_hash_s = 0;
@@ -3415,7 +3427,9 @@ struct drbd_conf *drbd_new_device(unsigned int minor)
 	q->backing_dev_info.congested_data = mdev;
 
 	blk_queue_make_request(q, drbd_make_request);
-	blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE >> 9);
+	/* Setting the max_hw_sectors to an odd value of 8kibyte here
+	   This triggers a max_bio_size message upon first attach or connect */
+	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;
@@ -3627,7 +3641,8 @@ struct meta_data_on_disk {
 	      /* `-- act_log->nr_elements <-- sync_conf.al_extents */
 	u32 bm_offset;         /* offset to the bitmap, from here */
 	u32 bm_bytes_per_bit;  /* BM_BLOCK_SIZE */
-	u32 reserved_u32[4];
+	u32 la_peer_max_bio_size;   /* last peer max_bio_size */
+	u32 reserved_u32[3];
 
 } __packed;
 
@@ -3668,6 +3683,7 @@ void drbd_md_sync(struct drbd_conf *mdev)
 	buffer->device_uuid = cpu_to_be64(mdev->ldev->md.device_uuid);
 
 	buffer->bm_offset = cpu_to_be32(mdev->ldev->md.bm_offset);
+	buffer->la_peer_max_bio_size = cpu_to_be32(mdev->peer_max_bio_size);
 
 	D_ASSERT(drbd_md_ss__(mdev, mdev->ldev) == mdev->ldev->md.md_offset);
 	sector = mdev->ldev->md.md_offset;
@@ -3751,6 +3767,15 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 	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);
+	if (mdev->state.conn < C_CONNECTED) {
+		int peer;
+		peer = be32_to_cpu(buffer->la_peer_max_bio_size);
+		peer = max_t(int, 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;
 
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 03b29f78a37d..515bcd948a43 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -272,9 +272,28 @@ static int _try_outdate_peer_async(void *data)
 {
 	struct drbd_conf *mdev = (struct drbd_conf *)data;
 	enum drbd_disk_state nps;
+	union drbd_state ns;
 
 	nps = drbd_try_outdate_peer(mdev);
-	drbd_request_state(mdev, NS(pdsk, nps));
+
+	/* Not using
+	   drbd_request_state(mdev, NS(pdsk, nps));
+	   here, because we might were able to re-establish the connection
+	   in the meantime. This can only partially be solved in the state's
+	   engine is_valid_state() and is_valid_state_transition()
+	   functions.
+
+	   nps can be D_INCONSISTENT, D_OUTDATED or D_UNKNOWN.
+	   pdsk == D_INCONSISTENT while conn >= C_CONNECTED is valid,
+	   therefore we have to have the pre state change check here.
+	*/
+	spin_lock_irq(&mdev->req_lock);
+	ns = mdev->state;
+	if (ns.conn < C_WF_REPORT_PARAMS) {
+		ns.pdsk = nps;
+		_drbd_set_state(mdev, ns, CS_VERBOSE, NULL);
+	}
+	spin_unlock_irq(&mdev->req_lock);
 
 	return 0;
 }
@@ -577,7 +596,7 @@ void drbd_resume_io(struct drbd_conf *mdev)
  * Returns 0 on success, negative return values indicate errors.
  * You should call drbd_md_sync() after calling this function.
  */
-enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *mdev, enum dds_flags flags) __must_hold(local)
+enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds_flags flags) __must_hold(local)
 {
 	sector_t prev_first_sect, prev_size; /* previous meta location */
 	sector_t la_size;
@@ -773,30 +792,78 @@ static int drbd_check_al_size(struct drbd_conf *mdev)
 	return 0;
 }
 
-void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_bio_size) __must_hold(local)
+static void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_bio_size)
 {
 	struct request_queue * const q = mdev->rq_queue;
-	struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;
-	int max_segments = mdev->ldev->dc.max_bio_bvecs;
-	int max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);
+	int max_hw_sectors = max_bio_size >> 9;
+	int max_segments = 0;
+
+	if (get_ldev_if_state(mdev, D_ATTACHING)) {
+		struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;
+
+		max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);
+		max_segments = mdev->ldev->dc.max_bio_bvecs;
+		put_ldev(mdev);
+	}
 
 	blk_queue_logical_block_size(q, 512);
 	blk_queue_max_hw_sectors(q, max_hw_sectors);
 	/* This is the workaround for "bio would need to, but cannot, be split" */
 	blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS);
 	blk_queue_segment_boundary(q, PAGE_CACHE_SIZE-1);
-	blk_queue_stack_limits(q, b);
 
-	dev_info(DEV, "max BIO size = %u\n", queue_max_hw_sectors(q) << 9);
+	if (get_ldev_if_state(mdev, D_ATTACHING)) {
+		struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;
+
+		blk_queue_stack_limits(q, b);
 
-	if (q->backing_dev_info.ra_pages != b->backing_dev_info.ra_pages) {
-		dev_info(DEV, "Adjusting my ra_pages to backing device's (%lu -> %lu)\n",
-		     q->backing_dev_info.ra_pages,
-		     b->backing_dev_info.ra_pages);
-		q->backing_dev_info.ra_pages = b->backing_dev_info.ra_pages;
+		if (q->backing_dev_info.ra_pages != b->backing_dev_info.ra_pages) {
+			dev_info(DEV, "Adjusting my ra_pages to backing device's (%lu -> %lu)\n",
+				 q->backing_dev_info.ra_pages,
+				 b->backing_dev_info.ra_pages);
+			q->backing_dev_info.ra_pages = b->backing_dev_info.ra_pages;
+		}
+		put_ldev(mdev);
 	}
 }
 
+void drbd_reconsider_max_bio_size(struct drbd_conf *mdev)
+{
+	int now, new, local, peer;
+
+	now = queue_max_hw_sectors(mdev->rq_queue) << 9;
+	local = mdev->local_max_bio_size; /* Eventually last known value, from volatile memory */
+	peer = mdev->peer_max_bio_size; /* Eventually last known value, from meta data */
+
+	if (get_ldev_if_state(mdev, D_ATTACHING)) {
+		local = queue_max_hw_sectors(mdev->ldev->backing_bdev->bd_disk->queue) << 9;
+		mdev->local_max_bio_size = local;
+		put_ldev(mdev);
+	}
+
+	/* We may ignore peer limits if the peer is modern enough.
+	   Because new from 8.3.8 onwards the peer can use multiple
+	   BIOs for a single peer_request */
+	if (mdev->state.conn >= C_CONNECTED) {
+		if (mdev->agreed_pro_version < 94)
+			peer = mdev->peer_max_bio_size;
+		else if (mdev->agreed_pro_version == 94)
+			peer = DRBD_MAX_SIZE_H80_PACKET;
+		else /* drbd 8.3.8 onwards */
+			peer = DRBD_MAX_BIO_SIZE;
+	}
+
+	new = min_t(int, local, peer);
+
+	if (mdev->state.role == R_PRIMARY && new < now)
+		dev_err(DEV, "ASSERT FAILED new < now; (%d < %d)\n", new, now);
+
+	if (new != now)
+		dev_info(DEV, "max BIO size = %u\n", new);
+
+	drbd_setup_queue_param(mdev, new);
+}
+
 /* serialize deconfig (worker exiting, doing cleanup)
  * and reconfig (drbdsetup disk, drbdsetup net)
  *
@@ -865,7 +932,6 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	struct block_device *bdev;
 	struct lru_cache *resync_lru = NULL;
 	union drbd_state ns, os;
-	unsigned int max_bio_size;
 	enum drbd_state_rv rv;
 	int cp_discovered = 0;
 	int logical_block_size;
@@ -1117,20 +1183,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	mdev->read_cnt = 0;
 	mdev->writ_cnt = 0;
 
-	max_bio_size = DRBD_MAX_BIO_SIZE;
-	if (mdev->state.conn == C_CONNECTED) {
-		/* We are Primary, Connected, and now attach a new local
-		 * backing store. We must not increase the user visible maximum
-		 * bio size on this device to something the peer may not be
-		 * able to handle. */
-		if (mdev->agreed_pro_version < 94)
-			max_bio_size = queue_max_hw_sectors(mdev->rq_queue) << 9;
-		else if (mdev->agreed_pro_version == 94)
-			max_bio_size = DRBD_MAX_SIZE_H80_PACKET;
-		/* else: drbd 8.3.9 and later, stay with default */
-	}
-
-	drbd_setup_queue_param(mdev, max_bio_size);
+	drbd_reconsider_max_bio_size(mdev);
 
 	/* If I am currently not R_PRIMARY,
 	 * but meta data primary indicator is set,
@@ -1152,7 +1205,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	    !drbd_md_test_flag(mdev->ldev, MDF_CONNECTED_IND))
 		set_bit(USE_DEGR_WFC_T, &mdev->flags);
 
-	dd = drbd_determin_dev_size(mdev, 0);
+	dd = drbd_determine_dev_size(mdev, 0);
 	if (dd == dev_size_error) {
 		retcode = ERR_NOMEM_BITMAP;
 		goto force_diskless_dec;
@@ -1281,11 +1334,19 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 static int drbd_nl_detach(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
 			  struct drbd_nl_cfg_reply *reply)
 {
+	enum drbd_ret_code retcode;
+	int ret;
 	drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */
-	reply->ret_code = drbd_request_state(mdev, NS(disk, D_DISKLESS));
-	if (mdev->state.disk == D_DISKLESS)
-		wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
+	retcode = drbd_request_state(mdev, NS(disk, D_FAILED));
+	/* D_FAILED will transition to DISKLESS. */
+	ret = wait_event_interruptible(mdev->misc_wait,
+			mdev->state.disk != D_FAILED);
 	drbd_resume_io(mdev);
+	if ((int)retcode == (int)SS_IS_DISKLESS)
+		retcode = SS_NOTHING_TO_DO;
+	if (ret)
+		retcode = ERR_INTR;
+	reply->ret_code = retcode;
 	return 0;
 }
 
@@ -1658,7 +1719,7 @@ static int drbd_nl_resize(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
 
 	mdev->ldev->dc.disk_size = (sector_t)rs.resize_size;
 	ddsf = (rs.resize_force ? DDSF_FORCED : 0) | (rs.no_resync ? DDSF_NO_RESYNC : 0);
-	dd = drbd_determin_dev_size(mdev, ddsf);
+	dd = drbd_determine_dev_size(mdev, ddsf);
 	drbd_md_sync(mdev);
 	put_ldev(mdev);
 	if (dd == dev_size_error) {
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index fd26666c0b08..25d32c5aa50a 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -333,7 +333,7 @@ struct drbd_epoch_entry *drbd_alloc_ee(struct drbd_conf *mdev,
 	if (!page)
 		goto fail;
 
-	INIT_HLIST_NODE(&e->colision);
+	INIT_HLIST_NODE(&e->collision);
 	e->epoch = NULL;
 	e->mdev = mdev;
 	e->pages = page;
@@ -356,7 +356,7 @@ void drbd_free_some_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e, int i
 		kfree(e->digest);
 	drbd_pp_free(mdev, e->pages, is_net);
 	D_ASSERT(atomic_read(&e->pending_bios) == 0);
-	D_ASSERT(hlist_unhashed(&e->colision));
+	D_ASSERT(hlist_unhashed(&e->collision));
 	mempool_free(e, drbd_ee_mempool);
 }
 
@@ -787,7 +787,7 @@ static int drbd_connect(struct drbd_conf *mdev)
 		}
 
 		if (sock && msock) {
-			schedule_timeout_interruptible(HZ / 10);
+			schedule_timeout_interruptible(mdev->net_conf->ping_timeo*HZ/10);
 			ok = drbd_socket_okay(mdev, &sock);
 			ok = drbd_socket_okay(mdev, &msock) && ok;
 			if (ok)
@@ -899,11 +899,6 @@ retry:
 
 	drbd_thread_start(&mdev->asender);
 
-	if (mdev->agreed_pro_version < 95 && get_ldev(mdev)) {
-		drbd_setup_queue_param(mdev, DRBD_MAX_SIZE_H80_PACKET);
-		put_ldev(mdev);
-	}
-
 	if (drbd_send_protocol(mdev) == -1)
 		return -1;
 	drbd_send_sync_param(mdev, &mdev->sync_conf);
@@ -1418,7 +1413,7 @@ static int e_end_resync_block(struct drbd_conf *mdev, struct drbd_work *w, int u
 	sector_t sector = e->sector;
 	int ok;
 
-	D_ASSERT(hlist_unhashed(&e->colision));
+	D_ASSERT(hlist_unhashed(&e->collision));
 
 	if (likely((e->flags & EE_WAS_ERROR) == 0)) {
 		drbd_set_in_sync(mdev, sector, e->size);
@@ -1487,7 +1482,7 @@ static int receive_DataReply(struct drbd_conf *mdev, enum drbd_packets cmd, unsi
 		return false;
 	}
 
-	/* hlist_del(&req->colision) is done in _req_may_be_done, to avoid
+	/* hlist_del(&req->collision) is done in _req_may_be_done, to avoid
 	 * special casing it there for the various failure cases.
 	 * still no race with drbd_fail_pending_reads */
 	ok = recv_dless_read(mdev, req, sector, data_size);
@@ -1558,11 +1553,11 @@ static int e_end_block(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 	 * P_WRITE_ACK / P_NEG_ACK, to get the sequence number right.  */
 	if (mdev->net_conf->two_primaries) {
 		spin_lock_irq(&mdev->req_lock);
-		D_ASSERT(!hlist_unhashed(&e->colision));
-		hlist_del_init(&e->colision);
+		D_ASSERT(!hlist_unhashed(&e->collision));
+		hlist_del_init(&e->collision);
 		spin_unlock_irq(&mdev->req_lock);
 	} else {
-		D_ASSERT(hlist_unhashed(&e->colision));
+		D_ASSERT(hlist_unhashed(&e->collision));
 	}
 
 	drbd_may_finish_epoch(mdev, e->epoch, EV_PUT + (cancel ? EV_CLEANUP : 0));
@@ -1579,8 +1574,8 @@ static int e_send_discard_ack(struct drbd_conf *mdev, struct drbd_work *w, int u
 	ok = drbd_send_ack(mdev, P_DISCARD_ACK, e);
 
 	spin_lock_irq(&mdev->req_lock);
-	D_ASSERT(!hlist_unhashed(&e->colision));
-	hlist_del_init(&e->colision);
+	D_ASSERT(!hlist_unhashed(&e->collision));
+	hlist_del_init(&e->collision);
 	spin_unlock_irq(&mdev->req_lock);
 
 	dec_unacked(mdev);
@@ -1755,7 +1750,7 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 
 		spin_lock_irq(&mdev->req_lock);
 
-		hlist_add_head(&e->colision, ee_hash_slot(mdev, sector));
+		hlist_add_head(&e->collision, ee_hash_slot(mdev, sector));
 
 #define OVERLAPS overlaps(i->sector, i->size, sector, size)
 		slot = tl_hash_slot(mdev, sector);
@@ -1765,7 +1760,7 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 			int have_conflict = 0;
 			prepare_to_wait(&mdev->misc_wait, &wait,
 				TASK_INTERRUPTIBLE);
-			hlist_for_each_entry(i, n, slot, colision) {
+			hlist_for_each_entry(i, n, slot, collision) {
 				if (OVERLAPS) {
 					/* only ALERT on first iteration,
 					 * we may be woken up early... */
@@ -1804,7 +1799,7 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 			}
 
 			if (signal_pending(current)) {
-				hlist_del_init(&e->colision);
+				hlist_del_init(&e->collision);
 
 				spin_unlock_irq(&mdev->req_lock);
 
@@ -1862,7 +1857,7 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 	dev_err(DEV, "submit failed, triggering re-connect\n");
 	spin_lock_irq(&mdev->req_lock);
 	list_del(&e->w.list);
-	hlist_del_init(&e->colision);
+	hlist_del_init(&e->collision);
 	spin_unlock_irq(&mdev->req_lock);
 	if (e->flags & EE_CALL_AL_COMPLETE_IO)
 		drbd_al_complete_io(mdev, e->sector);
@@ -2916,12 +2911,6 @@ disconnect:
 	return false;
 }
 
-static void drbd_setup_order_type(struct drbd_conf *mdev, int peer)
-{
-	/* sorry, we currently have no working implementation
-	 * of distributed TCQ */
-}
-
 /* warn if the arguments differ by more than 12.5% */
 static void warn_if_differ_considerably(struct drbd_conf *mdev,
 	const char *s, sector_t a, sector_t b)
@@ -2939,7 +2928,6 @@ static int receive_sizes(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 {
 	struct p_sizes *p = &mdev->data.rbuf.sizes;
 	enum determine_dev_size dd = unchanged;
-	unsigned int max_bio_size;
 	sector_t p_size, p_usize, my_usize;
 	int ldsc = 0; /* local disk size changed */
 	enum dds_flags ddsf;
@@ -2994,7 +2982,7 @@ static int receive_sizes(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 
 	ddsf = be16_to_cpu(p->dds_flags);
 	if (get_ldev(mdev)) {
-		dd = drbd_determin_dev_size(mdev, ddsf);
+		dd = drbd_determine_dev_size(mdev, ddsf);
 		put_ldev(mdev);
 		if (dd == dev_size_error)
 			return false;
@@ -3004,23 +2992,15 @@ static int receive_sizes(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 		drbd_set_my_capacity(mdev, p_size);
 	}
 
+	mdev->peer_max_bio_size = be32_to_cpu(p->max_bio_size);
+	drbd_reconsider_max_bio_size(mdev);
+
 	if (get_ldev(mdev)) {
 		if (mdev->ldev->known_size != drbd_get_capacity(mdev->ldev->backing_bdev)) {
 			mdev->ldev->known_size = drbd_get_capacity(mdev->ldev->backing_bdev);
 			ldsc = 1;
 		}
 
-		if (mdev->agreed_pro_version < 94)
-			max_bio_size = be32_to_cpu(p->max_bio_size);
-		else if (mdev->agreed_pro_version == 94)
-			max_bio_size = DRBD_MAX_SIZE_H80_PACKET;
-		else /* drbd 8.3.8 onwards */
-			max_bio_size = DRBD_MAX_BIO_SIZE;
-
-		if (max_bio_size != queue_max_hw_sectors(mdev->rq_queue) << 9)
-			drbd_setup_queue_param(mdev, max_bio_size);
-
-		drbd_setup_order_type(mdev, be16_to_cpu(p->queue_order_type));
 		put_ldev(mdev);
 	}
 
@@ -4275,7 +4255,7 @@ static struct drbd_request *_ack_id_to_req(struct drbd_conf *mdev,
 	struct hlist_node *n;
 	struct drbd_request *req;
 
-	hlist_for_each_entry(req, n, slot, colision) {
+	hlist_for_each_entry(req, n, slot, collision) {
 		if ((unsigned long)req == (unsigned long)id) {
 			if (req->sector != sector) {
 				dev_err(DEV, "_ack_id_to_req: found req %p but it has "
@@ -4554,6 +4534,7 @@ int drbd_asender(struct drbd_thread *thi)
 	int received = 0;
 	int expect   = sizeof(struct p_header80);
 	int empty;
+	int ping_timeout_active = 0;
 
 	sprintf(current->comm, "drbd%d_asender", mdev_to_minor(mdev));
 
@@ -4566,6 +4547,7 @@ int drbd_asender(struct drbd_thread *thi)
 			ERR_IF(!drbd_send_ping(mdev)) goto reconnect;
 			mdev->meta.socket->sk->sk_rcvtimeo =
 				mdev->net_conf->ping_timeo*HZ/10;
+			ping_timeout_active = 1;
 		}
 
 		/* conditionally cork;
@@ -4620,8 +4602,7 @@ int drbd_asender(struct drbd_thread *thi)
 			dev_err(DEV, "meta connection shut down by peer.\n");
 			goto reconnect;
 		} else if (rv == -EAGAIN) {
-			if (mdev->meta.socket->sk->sk_rcvtimeo ==
-			    mdev->net_conf->ping_timeo*HZ/10) {
+			if (ping_timeout_active) {
 				dev_err(DEV, "PingAck did not arrive in time.\n");
 				goto reconnect;
 			}
@@ -4660,6 +4641,11 @@ int drbd_asender(struct drbd_thread *thi)
 			if (!cmd->process(mdev, h))
 				goto reconnect;
 
+			/* the idle_timeout (ping-int)
+			 * has been restored in got_PingAck() */
+			if (cmd == get_asender_cmd(P_PING_ACK))
+				ping_timeout_active = 0;
+
 			buf	 = h;
 			received = 0;
 			expect	 = sizeof(struct p_header80);
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 5c0c8be1bb0a..3424d675b769 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -163,7 +163,7 @@ static void _about_to_complete_local_write(struct drbd_conf *mdev,
 		 * they must have been failed on the spot */
 #define OVERLAPS overlaps(sector, size, i->sector, i->size)
 		slot = tl_hash_slot(mdev, sector);
-		hlist_for_each_entry(i, n, slot, colision) {
+		hlist_for_each_entry(i, n, slot, collision) {
 			if (OVERLAPS) {
 				dev_alert(DEV, "LOGIC BUG: completed: %p %llus +%u; "
 				      "other: %p %llus +%u\n",
@@ -187,7 +187,7 @@ static void _about_to_complete_local_write(struct drbd_conf *mdev,
 #undef OVERLAPS
 #define OVERLAPS overlaps(sector, size, e->sector, e->size)
 		slot = ee_hash_slot(mdev, req->sector);
-		hlist_for_each_entry(e, n, slot, colision) {
+		hlist_for_each_entry(e, n, slot, collision) {
 			if (OVERLAPS) {
 				wake_up(&mdev->misc_wait);
 				break;
@@ -260,8 +260,8 @@ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
 
 		/* remove the request from the conflict detection
 		 * respective block_id verification hash */
-		if (!hlist_unhashed(&req->colision))
-			hlist_del(&req->colision);
+		if (!hlist_unhashed(&req->collision))
+			hlist_del(&req->collision);
 		else
 			D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0);
 
@@ -329,7 +329,7 @@ static int _req_conflicts(struct drbd_request *req)
 	struct hlist_node *n;
 	struct hlist_head *slot;
 
-	D_ASSERT(hlist_unhashed(&req->colision));
+	D_ASSERT(hlist_unhashed(&req->collision));
 
 	if (!get_net_conf(mdev))
 		return 0;
@@ -341,7 +341,7 @@ static int _req_conflicts(struct drbd_request *req)
 
 #define OVERLAPS overlaps(i->sector, i->size, sector, size)
 	slot = tl_hash_slot(mdev, sector);
-	hlist_for_each_entry(i, n, slot, colision) {
+	hlist_for_each_entry(i, n, slot, collision) {
 		if (OVERLAPS) {
 			dev_alert(DEV, "%s[%u] Concurrent local write detected! "
 			      "[DISCARD L] new: %llus +%u; "
@@ -359,7 +359,7 @@ static int _req_conflicts(struct drbd_request *req)
 #undef OVERLAPS
 #define OVERLAPS overlaps(e->sector, e->size, sector, size)
 		slot = ee_hash_slot(mdev, sector);
-		hlist_for_each_entry(e, n, slot, colision) {
+		hlist_for_each_entry(e, n, slot, collision) {
 			if (OVERLAPS) {
 				dev_alert(DEV, "%s[%u] Concurrent remote write detected!"
 				      " [DISCARD L] new: %llus +%u; "
@@ -491,7 +491,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 
 		/* so we can verify the handle in the answer packet
 		 * corresponding hlist_del is in _req_may_be_done() */
-		hlist_add_head(&req->colision, ar_hash_slot(mdev, req->sector));
+		hlist_add_head(&req->collision, ar_hash_slot(mdev, req->sector));
 
 		set_bit(UNPLUG_REMOTE, &mdev->flags);
 
@@ -507,7 +507,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 		/* assert something? */
 		/* from drbd_make_request_common only */
 
-		hlist_add_head(&req->colision, tl_hash_slot(mdev, req->sector));
+		hlist_add_head(&req->collision, tl_hash_slot(mdev, req->sector));
 		/* corresponding hlist_del is in _req_may_be_done() */
 
 		/* NOTE
@@ -1033,7 +1033,7 @@ fail_conflicting:
 	err = 0;
 
 fail_free_complete:
-	if (rw == WRITE && local)
+	if (req->rq_state & RQ_IN_ACT_LOG)
 		drbd_al_complete_io(mdev, sector);
 fail_and_free_req:
 	if (local) {
diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h
index 32e2c3e6a813..68a234a5fdc5 100644
--- a/drivers/block/drbd/drbd_req.h
+++ b/drivers/block/drbd/drbd_req.h
@@ -256,7 +256,7 @@ static inline struct drbd_request *_ar_id_to_req(struct drbd_conf *mdev,
 	struct hlist_node *n;
 	struct drbd_request *req;
 
-	hlist_for_each_entry(req, n, slot, colision) {
+	hlist_for_each_entry(req, n, slot, collision) {
 		if ((unsigned long)req == (unsigned long)id) {
 			D_ASSERT(req->sector == sector);
 			return req;
@@ -291,7 +291,7 @@ static inline struct drbd_request *drbd_req_new(struct drbd_conf *mdev,
 		req->epoch       = 0;
 		req->sector      = bio_src->bi_sector;
 		req->size        = bio_src->bi_size;
-		INIT_HLIST_NODE(&req->colision);
+		INIT_HLIST_NODE(&req->collision);
 		INIT_LIST_HEAD(&req->tl_requests);
 		INIT_LIST_HEAD(&req->w.list);
 	}
@@ -323,6 +323,7 @@ extern int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 extern void complete_master_bio(struct drbd_conf *mdev,
 		struct bio_and_error *m);
 extern void request_timer_fn(unsigned long data);
+extern void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what);
 
 /* use this if you don't want to deal with calling complete_master_bio()
  * outside the spinlock, e.g. when walking some list on cleanup. */
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index f7e6c92f8d03..4d76b06b6b20 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -126,7 +126,7 @@ static void drbd_endio_write_sec_final(struct drbd_epoch_entry *e) __releases(lo
 	list_del(&e->w.list); /* has been on active_ee or sync_ee */
 	list_add_tail(&e->w.list, &mdev->done_ee);
 
-	/* No hlist_del_init(&e->colision) here, we did not send the Ack yet,
+	/* No hlist_del_init(&e->collision) here, we did not send the Ack yet,
 	 * neither did we wake possibly waiting conflicting requests.
 	 * done from "drbd_process_done_ee" within the appropriate w.cb
 	 * (e_end_block/e_end_resync_block) or from _drbd_clear_done_ee */
@@ -297,42 +297,48 @@ void drbd_csum_bio(struct drbd_conf *mdev, struct crypto_hash *tfm, struct bio *
 	crypto_hash_final(&desc, digest);
 }
 
-static int w_e_send_csum(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
+/* TODO merge common code with w_e_end_ov_req */
+int w_e_send_csum(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 {
 	struct drbd_epoch_entry *e = container_of(w, struct drbd_epoch_entry, w);
 	int digest_size;
 	void *digest;
-	int ok;
+	int ok = 1;
 
 	D_ASSERT(e->block_id == DRBD_MAGIC + 0xbeef);
 
-	if (unlikely(cancel)) {
-		drbd_free_ee(mdev, e);
-		return 1;
-	}
+	if (unlikely(cancel))
+		goto out;
 
-	if (likely((e->flags & EE_WAS_ERROR) == 0)) {
-		digest_size = crypto_hash_digestsize(mdev->csums_tfm);
-		digest = kmalloc(digest_size, GFP_NOIO);
-		if (digest) {
-			drbd_csum_ee(mdev, mdev->csums_tfm, e, digest);
+	if (likely((e->flags & EE_WAS_ERROR) != 0))
+		goto out;
 
-			inc_rs_pending(mdev);
-			ok = drbd_send_drequest_csum(mdev,
-						     e->sector,
-						     e->size,
-						     digest,
-						     digest_size,
-						     P_CSUM_RS_REQUEST);
-			kfree(digest);
-		} else {
-			dev_err(DEV, "kmalloc() of digest failed.\n");
-			ok = 0;
-		}
-	} else
-		ok = 1;
+	digest_size = crypto_hash_digestsize(mdev->csums_tfm);
+	digest = kmalloc(digest_size, GFP_NOIO);
+	if (digest) {
+		sector_t sector = e->sector;
+		unsigned int size = e->size;
+		drbd_csum_ee(mdev, mdev->csums_tfm, e, digest);
+		/* Free e and pages before send.
+		 * In case we block on congestion, we could otherwise run into
+		 * some distributed deadlock, if the other side blocks on
+		 * congestion as well, because our receiver blocks in
+		 * drbd_pp_alloc due to pp_in_use > max_buffers. */
+		drbd_free_ee(mdev, e);
+		e = NULL;
+		inc_rs_pending(mdev);
+		ok = drbd_send_drequest_csum(mdev, sector, size,
+					     digest, digest_size,
+					     P_CSUM_RS_REQUEST);
+		kfree(digest);
+	} else {
+		dev_err(DEV, "kmalloc() of digest failed.\n");
+		ok = 0;
+	}
 
-	drbd_free_ee(mdev, e);
+out:
+	if (e)
+		drbd_free_ee(mdev, e);
 
 	if (unlikely(!ok))
 		dev_err(DEV, "drbd_send_drequest(..., csum) failed\n");
@@ -834,7 +840,7 @@ int drbd_resync_finished(struct drbd_conf *mdev)
 			const int ratio =
 				(t == 0)     ? 0 :
 			(t < 100000) ? ((s*100)/t) : (s/(t/100));
-			dev_info(DEV, "%u %% had equal check sums, eliminated: %luK; "
+			dev_info(DEV, "%u %% had equal checksums, eliminated: %luK; "
 			     "transferred %luK total %luK\n",
 			     ratio,
 			     Bit2KB(mdev->rs_same_csum),
@@ -1071,9 +1077,12 @@ int w_e_end_csum_rs_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 	return ok;
 }
 
+/* TODO merge common code with w_e_send_csum */
 int w_e_end_ov_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 {
 	struct drbd_epoch_entry *e = container_of(w, struct drbd_epoch_entry, w);
+	sector_t sector = e->sector;
+	unsigned int size = e->size;
 	int digest_size;
 	void *digest;
 	int ok = 1;
@@ -1093,17 +1102,25 @@ int w_e_end_ov_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 	else
 		memset(digest, 0, digest_size);
 
+	/* Free e and pages before send.
+	 * In case we block on congestion, we could otherwise run into
+	 * some distributed deadlock, if the other side blocks on
+	 * congestion as well, because our receiver blocks in
+	 * drbd_pp_alloc due to pp_in_use > max_buffers. */
+	drbd_free_ee(mdev, e);
+	e = NULL;
 	inc_rs_pending(mdev);
-	ok = drbd_send_drequest_csum(mdev, e->sector, e->size,
-				     digest, digest_size, P_OV_REPLY);
+	ok = drbd_send_drequest_csum(mdev, sector, size,
+				     digest, digest_size,
+				     P_OV_REPLY);
 	if (!ok)
 		dec_rs_pending(mdev);
 	kfree(digest);
 
 out:
-	drbd_free_ee(mdev, e);
+	if (e)
+		drbd_free_ee(mdev, e);
 	dec_unacked(mdev);
-
 	return ok;
 }
 
@@ -1122,8 +1139,10 @@ int w_e_end_ov_reply(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 {
 	struct drbd_epoch_entry *e = container_of(w, struct drbd_epoch_entry, w);
 	struct digest_info *di;
-	int digest_size;
 	void *digest;
+	sector_t sector = e->sector;
+	unsigned int size = e->size;
+	int digest_size;
 	int ok, eq = 0;
 
 	if (unlikely(cancel)) {
@@ -1153,16 +1172,21 @@ int w_e_end_ov_reply(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 		}
 	}
 
-	dec_unacked(mdev);
+		/* Free e and pages before send.
+		 * In case we block on congestion, we could otherwise run into
+		 * some distributed deadlock, if the other side blocks on
+		 * congestion as well, because our receiver blocks in
+		 * drbd_pp_alloc due to pp_in_use > max_buffers. */
+	drbd_free_ee(mdev, e);
 	if (!eq)
-		drbd_ov_oos_found(mdev, e->sector, e->size);
+		drbd_ov_oos_found(mdev, sector, size);
 	else
 		ov_oos_print(mdev);
 
-	ok = drbd_send_ack_ex(mdev, P_OV_RESULT, e->sector, e->size,
+	ok = drbd_send_ack_ex(mdev, P_OV_RESULT, sector, size,
 			      eq ? ID_IN_SYNC : ID_OUT_OF_SYNC);
 
-	drbd_free_ee(mdev, e);
+	dec_unacked(mdev);
 
 	--mdev->ov_left;