Merge branch 'for-4.8/drivers' of git://git.kernel.dk/linux-block

Pull block driver updates from Jens Axboe: "This branch also contains core changes. I've come to the conclusion that from 4.9 and forward, I'll be doing just a single branch. We often have dependencies between core and drivers, and it's hard to always split them up appropriately without pulling core into drivers when that happens. That said, this contains: - separate secure erase type for the core block layer, from Christoph. - set of discard fixes, from Christoph. - bio shrinking fixes from Christoph, as a followup up to the op/flags change in the core branch. - map and append request fixes from Christoph. - NVMeF (NVMe over Fabrics) code from Christoph. This is pretty exciting! - nvme-loop fixes from Arnd. - removal of ->driverfs_dev from Dan, after providing a device_add_disk() helper. - bcache fixes from Bhaktipriya and Yijing. - cdrom subchannel read fix from Vchannaiah. - set of lightnvm updates from Wenwei, Matias, Johannes, and Javier. - set of drbd updates and fixes from Fabian, Lars, and Philipp. - mg_disk error path fix from Bart. - user notification for failed device add for loop, from Minfei. - NVMe in general: + NVMe delay quirk from Guilherme. + SR-IOV support and command retry limits from Keith. + fix for memory-less NUMA node from Masayoshi. + use UINT_MAX for discard sectors, from Minfei. + cancel IO fixes from Ming. + don't allocate unused major, from Neil. + error code fixup from Dan. + use constants for PSDT/FUSE from James. + variable init fix from Jay. + fabrics fixes from Ming, Sagi, and Wei. + various fixes" * 'for-4.8/drivers' of git://git.kernel.dk/linux-block: (115 commits) nvme/pci: Provide SR-IOV support nvme: initialize variable before logical OR'ing it block: unexport various bio mapping helpers scsi/osd: open code blk_make_request target: stop using blk_make_request block: simplify and export blk_rq_append_bio block: ensure bios return from blk_get_request are properly initialized virtio_blk: use blk_rq_map_kern memstick: don't allow REQ_TYPE_BLOCK_PC requests block: shrink bio size again block: simplify and cleanup bvec pool handling block: get rid of bio_rw and READA block: don't ignore -EOPNOTSUPP blkdev_issue_write_same block: introduce BLKDEV_DISCARD_ZERO to fix zeroout NVMe: don't allocate unused nvme_major nvme: avoid crashes when node 0 is memoryless node. nvme: Limit command retries loop: Make user notify for adding loop device failed nvme-loop: fix nvme-loop Kconfig dependencies nvmet: fix return value check in nvmet_subsys_alloc() ...
author: Linus Torvalds <torvalds@linux-foundation.org> 2016-07-26 15:37:51 -0700
committer: Linus Torvalds <torvalds@linux-foundation.org> 2016-07-26 15:37:51 -0700
commit: 3fc9d690936fb2e20e180710965ba2cc3a0881f8 (patch)
tree: eaf4d9f788ee4d17cd40a116413873b7f80f9aa7 /drivers/block/drbd
parent: d05d7f40791ccbb6e543cc5dd6a6aa08fc71d635 (diff)
parent: 13880f5b57adf34d050cf7e229a6326da45a7347 (diff)
16 files changed, 1218 insertions, 319 deletions
diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index d524973f94b3..0a1aaf8c24c4 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -258,7 +258,7 @@ bool drbd_al_begin_io_fastpath(struct drbd_device *device, struct drbd_interval
 	unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 	unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 
-	D_ASSERT(device, (unsigned)(last - first) <= 1);
+	D_ASSERT(device, first <= last);
 	D_ASSERT(device, atomic_read(&device->local_cnt) > 0);
 
 	/* FIXME figure out a fast path for bios crossing AL extent boundaries */
@@ -341,6 +341,8 @@ static int __al_write_transaction(struct drbd_device *device, struct al_transact
 
 	i = 0;
 
+	drbd_bm_reset_al_hints(device);
+
 	/* Even though no one can start to change this list
 	 * once we set the LC_LOCKED -- from drbd_al_begin_io(),
 	 * lc_try_lock_for_transaction() --, someone may still
@@ -770,10 +772,18 @@ static bool lazy_bitmap_update_due(struct drbd_device *device)
 
 static void maybe_schedule_on_disk_bitmap_update(struct drbd_device *device, bool rs_done)
 {
-	if (rs_done)
-		set_bit(RS_DONE, &device->flags);
-		/* and also set RS_PROGRESS below */
-	else if (!lazy_bitmap_update_due(device))
+	if (rs_done) {
+		struct drbd_connection *connection = first_peer_device(device)->connection;
+		if (connection->agreed_pro_version <= 95 ||
+		    is_sync_target_state(device->state.conn))
+			set_bit(RS_DONE, &device->flags);
+			/* and also set RS_PROGRESS below */
+
+		/* Else: rather wait for explicit notification via receive_state,
+		 * to avoid uuids-rotated-too-fast causing full resync
+		 * in next handshake, in case the replication link breaks
+		 * at the most unfortunate time... */
+	} else if (!lazy_bitmap_update_due(device))
 		return;
 
 	drbd_device_post_work(device, RS_PROGRESS);
@@ -832,6 +842,13 @@ static int update_sync_bits(struct drbd_device *device,
 	return count;
 }
 
+static bool plausible_request_size(int size)
+{
+	return size > 0
+		&& size <= DRBD_MAX_BATCH_BIO_SIZE
+		&& IS_ALIGNED(size, 512);
+}
+
 /* clear the bit corresponding to the piece of storage in question:
  * size byte of data starting from sector.  Only clear a bits of the affected
  * one ore more _aligned_ BM_BLOCK_SIZE blocks.
@@ -851,7 +868,7 @@ int __drbd_change_sync(struct drbd_device *device, sector_t sector, int size,
 	if ((mode == SET_OUT_OF_SYNC) && size == 0)
 		return 0;
 
-	if (size <= 0 || !IS_ALIGNED(size, 512) || size > DRBD_MAX_DISCARD_SIZE) {
+	if (!plausible_request_size(size)) {
 		drbd_err(device, "%s: sector=%llus size=%d nonsense!\n",
 				drbd_change_sync_fname[mode],
 				(unsigned long long)sector, size);
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index e5d89f623b90..ab62b81c2ca7 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -96,6 +96,13 @@ struct drbd_bitmap {
 	struct page **bm_pages;
 	spinlock_t bm_lock;
 
+	/* exclusively to be used by __al_write_transaction(),
+	 * drbd_bm_mark_for_writeout() and
+	 * and drbd_bm_write_hinted() -> bm_rw() called from there.
+	 */
+	unsigned int n_bitmap_hints;
+	unsigned int al_bitmap_hints[AL_UPDATES_PER_TRANSACTION];
+
 	/* see LIMITATIONS: above */
 
 	unsigned long bm_set;       /* nr of set bits; THINK maybe atomic_t? */
@@ -242,6 +249,11 @@ static void bm_set_page_need_writeout(struct page *page)
 	set_bit(BM_PAGE_NEED_WRITEOUT, &page_private(page));
 }
 
+void drbd_bm_reset_al_hints(struct drbd_device *device)
+{
+	device->bitmap->n_bitmap_hints = 0;
+}
+
 /**
  * drbd_bm_mark_for_writeout() - mark a page with a "hint" to be considered for writeout
  * @device:	DRBD device.
@@ -253,6 +265,7 @@ static void bm_set_page_need_writeout(struct page *page)
  */
 void drbd_bm_mark_for_writeout(struct drbd_device *device, int page_nr)
 {
+	struct drbd_bitmap *b = device->bitmap;
 	struct page *page;
 	if (page_nr >= device->bitmap->bm_number_of_pages) {
 		drbd_warn(device, "BAD: page_nr: %u, number_of_pages: %u\n",
@@ -260,7 +273,9 @@ void drbd_bm_mark_for_writeout(struct drbd_device *device, int page_nr)
 		return;
 	}
 	page = device->bitmap->bm_pages[page_nr];
-	set_bit(BM_PAGE_HINT_WRITEOUT, &page_private(page));
+	BUG_ON(b->n_bitmap_hints >= ARRAY_SIZE(b->al_bitmap_hints));
+	if (!test_and_set_bit(BM_PAGE_HINT_WRITEOUT, &page_private(page)))
+		b->al_bitmap_hints[b->n_bitmap_hints++] = page_nr;
 }
 
 static int bm_test_page_unchanged(struct page *page)
@@ -427,8 +442,7 @@ static struct page **bm_realloc_pages(struct drbd_bitmap *b, unsigned long want)
 }
 
 /*
- * called on driver init only. TODO call when a device is created.
- * allocates the drbd_bitmap, and stores it in device->bitmap.
+ * allocates the drbd_bitmap and stores it in device->bitmap.
  */
 int drbd_bm_init(struct drbd_device *device)
 {
@@ -633,7 +647,8 @@ int drbd_bm_resize(struct drbd_device *device, sector_t capacity, int set_new_bi
 	unsigned long bits, words, owords, obits;
 	unsigned long want, have, onpages; /* number of pages */
 	struct page **npages, **opages = NULL;
-	int err = 0, growing;
+	int err = 0;
+	bool growing;
 
 	if (!expect(b))
 		return -ENOMEM;
@@ -1030,7 +1045,7 @@ static int bm_rw(struct drbd_device *device, const unsigned int flags, unsigned
 {
 	struct drbd_bm_aio_ctx *ctx;
 	struct drbd_bitmap *b = device->bitmap;
-	int num_pages, i, count = 0;
+	unsigned int num_pages, i, count = 0;
 	unsigned long now;
 	char ppb[10];
 	int err = 0;
@@ -1078,16 +1093,37 @@ static int bm_rw(struct drbd_device *device, const unsigned int flags, unsigned
 	now = jiffies;
 
 	/* let the layers below us try to merge these bios... */
-	for (i = 0; i < num_pages; i++) {
-		/* ignore completely unchanged pages */
-		if (lazy_writeout_upper_idx && i == lazy_writeout_upper_idx)
-			break;
-		if (!(flags & BM_AIO_READ)) {
-			if ((flags & BM_AIO_WRITE_HINTED) &&
-			    !test_and_clear_bit(BM_PAGE_HINT_WRITEOUT,
-				    &page_private(b->bm_pages[i])))
-				continue;
 
+	if (flags & BM_AIO_READ) {
+		for (i = 0; i < num_pages; i++) {
+			atomic_inc(&ctx->in_flight);
+			bm_page_io_async(ctx, i);
+			++count;
+			cond_resched();
+		}
+	} else if (flags & BM_AIO_WRITE_HINTED) {
+		/* ASSERT: BM_AIO_WRITE_ALL_PAGES is not set. */
+		unsigned int hint;
+		for (hint = 0; hint < b->n_bitmap_hints; hint++) {
+			i = b->al_bitmap_hints[hint];
+			if (i >= num_pages) /* == -1U: no hint here. */
+				continue;
+			/* Several AL-extents may point to the same page. */
+			if (!test_and_clear_bit(BM_PAGE_HINT_WRITEOUT,
+			    &page_private(b->bm_pages[i])))
+				continue;
+			/* Has it even changed? */
+			if (bm_test_page_unchanged(b->bm_pages[i]))
+				continue;
+			atomic_inc(&ctx->in_flight);
+			bm_page_io_async(ctx, i);
+			++count;
+		}
+	} else {
+		for (i = 0; i < num_pages; i++) {
+			/* ignore completely unchanged pages */
+			if (lazy_writeout_upper_idx && i == lazy_writeout_upper_idx)
+				break;
 			if (!(flags & BM_AIO_WRITE_ALL_PAGES) &&
 			    bm_test_page_unchanged(b->bm_pages[i])) {
 				dynamic_drbd_dbg(device, "skipped bm write for idx %u\n", i);
@@ -1100,11 +1136,11 @@ static int bm_rw(struct drbd_device *device, const unsigned int flags, unsigned
 				dynamic_drbd_dbg(device, "skipped bm lazy write for idx %u\n", i);
 				continue;
 			}
+			atomic_inc(&ctx->in_flight);
+			bm_page_io_async(ctx, i);
+			++count;
+			cond_resched();
 		}
-		atomic_inc(&ctx->in_flight);
-		bm_page_io_async(ctx, i);
-		++count;
-		cond_resched();
 	}
 
 	/*
@@ -1121,10 +1157,14 @@ static int bm_rw(struct drbd_device *device, const unsigned int flags, unsigned
 		kref_put(&ctx->kref, &drbd_bm_aio_ctx_destroy);
 
 	/* summary for global bitmap IO */
-	if (flags == 0)
-		drbd_info(device, "bitmap %s of %u pages took %lu jiffies\n",
-			 (flags & BM_AIO_READ) ? "READ" : "WRITE",
-			 count, jiffies - now);
+	if (flags == 0) {
+		unsigned int ms = jiffies_to_msecs(jiffies - now);
+		if (ms > 5) {
+			drbd_info(device, "bitmap %s of %u pages took %u ms\n",
+				 (flags & BM_AIO_READ) ? "READ" : "WRITE",
+				 count, ms);
+		}
+	}
 
 	if (ctx->error) {
 		drbd_alert(device, "we had at least one MD IO ERROR during bitmap IO\n");
diff --git a/drivers/block/drbd/drbd_debugfs.c b/drivers/block/drbd/drbd_debugfs.c
index 4de95bbff486..be91a8d7c22a 100644
--- a/drivers/block/drbd/drbd_debugfs.c
+++ b/drivers/block/drbd/drbd_debugfs.c
@@ -237,14 +237,9 @@ static void seq_print_peer_request_flags(struct seq_file *m, struct drbd_peer_re
 	seq_print_rq_state_bit(m, f & EE_SEND_WRITE_ACK, &sep, "C");
 	seq_print_rq_state_bit(m, f & EE_MAY_SET_IN_SYNC, &sep, "set-in-sync");
 
-	if (f & EE_IS_TRIM) {
-		seq_putc(m, sep);
-		sep = '|';
-		if (f & EE_IS_TRIM_USE_ZEROOUT)
-			seq_puts(m, "zero-out");
-		else
-			seq_puts(m, "trim");
-	}
+	if (f & EE_IS_TRIM)
+		__seq_print_rq_state_bit(m, f & EE_IS_TRIM_USE_ZEROOUT, &sep, "zero-out", "trim");
+	seq_print_rq_state_bit(m, f & EE_WRITE_SAME, &sep, "write-same");
 	seq_putc(m, '\n');
 }
 
@@ -908,7 +903,7 @@ static int drbd_version_open(struct inode *inode, struct file *file)
 	return single_open(file, drbd_version_show, NULL);
 }
 
-static struct file_operations drbd_version_fops = {
+static const struct file_operations drbd_version_fops = {
 	.owner = THIS_MODULE,
 	.open = drbd_version_open,
 	.llseek = seq_lseek,
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index a64c645b4184..7b54354976a5 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -468,9 +468,15 @@ enum {
 	/* this is/was a write request */
 	__EE_WRITE,
 
+	/* this is/was a write same request */
+	__EE_WRITE_SAME,
+
 	/* this originates from application on peer
 	 * (not some resync or verify or other DRBD internal request) */
 	__EE_APPLICATION,
+
+	/* If it contains only 0 bytes, send back P_RS_DEALLOCATED */
+	__EE_RS_THIN_REQ,
 };
 #define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
 #define EE_MAY_SET_IN_SYNC     (1<<__EE_MAY_SET_IN_SYNC)
@@ -484,7 +490,9 @@ enum {
 #define EE_IN_INTERVAL_TREE	(1<<__EE_IN_INTERVAL_TREE)
 #define EE_SUBMITTED		(1<<__EE_SUBMITTED)
 #define EE_WRITE		(1<<__EE_WRITE)
+#define EE_WRITE_SAME		(1<<__EE_WRITE_SAME)
 #define EE_APPLICATION		(1<<__EE_APPLICATION)
+#define EE_RS_THIN_REQ		(1<<__EE_RS_THIN_REQ)
 
 /* flag bits per device */
 enum {
@@ -1123,6 +1131,7 @@ extern int drbd_send_ov_request(struct drbd_peer_device *, sector_t sector, int
 extern int drbd_send_bitmap(struct drbd_device *device);
 extern void drbd_send_sr_reply(struct drbd_peer_device *, enum drbd_state_rv retcode);
 extern void conn_send_sr_reply(struct drbd_connection *connection, enum drbd_state_rv retcode);
+extern int drbd_send_rs_deallocated(struct drbd_peer_device *, struct drbd_peer_request *);
 extern void drbd_backing_dev_free(struct drbd_device *device, struct drbd_backing_dev *ldev);
 extern void drbd_device_cleanup(struct drbd_device *device);
 void drbd_print_uuids(struct drbd_device *device, const char *text);
@@ -1342,11 +1351,11 @@ struct bm_extent {
 #define DRBD_MAX_SIZE_H80_PACKET (1U << 15) /* Header 80 only allows packets up to 32KiB data */
 #define DRBD_MAX_BIO_SIZE_P95    (1U << 17) /* Protocol 95 to 99 allows bios up to 128KiB */
 
-/* For now, don't allow more than one activity log extent worth of data
- * to be discarded in one go. We may need to rework drbd_al_begin_io()
- * to allow for even larger discard ranges */
-#define DRBD_MAX_DISCARD_SIZE	AL_EXTENT_SIZE
-#define DRBD_MAX_DISCARD_SECTORS (DRBD_MAX_DISCARD_SIZE >> 9)
+/* For now, don't allow more than half of what we can "activate" in one
+ * activity log transaction to be discarded in one go. We may need to rework
+ * drbd_al_begin_io() to allow for even larger discard ranges */
+#define DRBD_MAX_BATCH_BIO_SIZE	 (AL_UPDATES_PER_TRANSACTION/2*AL_EXTENT_SIZE)
+#define DRBD_MAX_BBIO_SECTORS    (DRBD_MAX_BATCH_BIO_SIZE >> 9)
 
 extern int  drbd_bm_init(struct drbd_device *device);
 extern int  drbd_bm_resize(struct drbd_device *device, sector_t sectors, int set_new_bits);
@@ -1369,6 +1378,7 @@ extern int  drbd_bm_e_weight(struct drbd_device *device, unsigned long enr);
 extern int  drbd_bm_read(struct drbd_device *device) __must_hold(local);
 extern void drbd_bm_mark_for_writeout(struct drbd_device *device, int page_nr);
 extern int  drbd_bm_write(struct drbd_device *device) __must_hold(local);
+extern void drbd_bm_reset_al_hints(struct drbd_device *device) __must_hold(local);
 extern int  drbd_bm_write_hinted(struct drbd_device *device) __must_hold(local);
 extern int  drbd_bm_write_lazy(struct drbd_device *device, unsigned upper_idx) __must_hold(local);
 extern int drbd_bm_write_all(struct drbd_device *device) __must_hold(local);
@@ -1483,12 +1493,14 @@ enum determine_dev_size {
 extern enum determine_dev_size
 drbd_determine_dev_size(struct drbd_device *, enum dds_flags, struct resize_parms *) __must_hold(local);
 extern void resync_after_online_grow(struct drbd_device *);
-extern void drbd_reconsider_max_bio_size(struct drbd_device *device, struct drbd_backing_dev *bdev);
+extern void drbd_reconsider_queue_parameters(struct drbd_device *device,
+			struct drbd_backing_dev *bdev, struct o_qlim *o);
 extern enum drbd_state_rv drbd_set_role(struct drbd_device *device,
 					enum drbd_role new_role,
 					int force);
 extern bool conn_try_outdate_peer(struct drbd_connection *connection);
 extern void conn_try_outdate_peer_async(struct drbd_connection *connection);
+extern enum drbd_peer_state conn_khelper(struct drbd_connection *connection, char *cmd);
 extern int drbd_khelper(struct drbd_device *device, char *cmd);
 
 /* drbd_worker.c */
@@ -1548,6 +1560,8 @@ extern void start_resync_timer_fn(unsigned long data);
 extern void drbd_endio_write_sec_final(struct drbd_peer_request *peer_req);
 
 /* drbd_receiver.c */
+extern int drbd_issue_discard_or_zero_out(struct drbd_device *device,
+		sector_t start, unsigned int nr_sectors, bool discard);
 extern int drbd_receiver(struct drbd_thread *thi);
 extern int drbd_ack_receiver(struct drbd_thread *thi);
 extern void drbd_send_ping_wf(struct work_struct *ws);
@@ -1561,7 +1575,7 @@ extern int drbd_submit_peer_request(struct drbd_device *,
 extern int drbd_free_peer_reqs(struct drbd_device *, struct list_head *);
 extern struct drbd_peer_request *drbd_alloc_peer_req(struct drbd_peer_device *, u64,
 						     sector_t, unsigned int,
-						     bool,
+						     unsigned int,
 						     gfp_t) __must_hold(local);
 extern void __drbd_free_peer_req(struct drbd_device *, struct drbd_peer_request *,
 				 int);
@@ -1635,8 +1649,6 @@ void drbd_bump_write_ordering(struct drbd_resource *resource, struct drbd_backin
 /* drbd_proc.c */
 extern struct proc_dir_entry *drbd_proc;
 extern const struct file_operations drbd_proc_fops;
-extern const char *drbd_conn_str(enum drbd_conns s);
-extern const char *drbd_role_str(enum drbd_role s);
 
 /* drbd_actlog.c */
 extern bool drbd_al_begin_io_prepare(struct drbd_device *device, struct drbd_interval *i);
@@ -2095,13 +2107,22 @@ static inline void _sub_unacked(struct drbd_device *device, int n, const char *f
 	ERR_IF_CNT_IS_NEGATIVE(unacked_cnt, func, line);
 }
 
+static inline bool is_sync_target_state(enum drbd_conns connection_state)
+{
+	return	connection_state == C_SYNC_TARGET ||
+		connection_state == C_PAUSED_SYNC_T;
+}
+
+static inline bool is_sync_source_state(enum drbd_conns connection_state)
+{
+	return	connection_state == C_SYNC_SOURCE ||
+		connection_state == C_PAUSED_SYNC_S;
+}
+
 static inline bool is_sync_state(enum drbd_conns connection_state)
 {
-	return
-	   (connection_state == C_SYNC_SOURCE
-	||  connection_state == C_SYNC_TARGET
-	||  connection_state == C_PAUSED_SYNC_S
-	||  connection_state == C_PAUSED_SYNC_T);
+	return	is_sync_source_state(connection_state) ||
+		is_sync_target_state(connection_state);
 }
 
 /**
diff --git a/drivers/block/drbd/drbd_interval.h b/drivers/block/drbd/drbd_interval.h
index f210543f05f4..23c5a94428d2 100644
--- a/drivers/block/drbd/drbd_interval.h
+++ b/drivers/block/drbd/drbd_interval.h
@@ -6,13 +6,13 @@
 
 struct drbd_interval {
 	struct rb_node rb;
-	sector_t sector;	/* start sector of the interval */
-	unsigned int size;	/* size in bytes */
-	sector_t end;		/* highest interval end in subtree */
-	int local:1		/* local or remote request? */;
-	int waiting:1;		/* someone is waiting for this to complete */
-	int completed:1;	/* this has been completed already;
-				 * ignore for conflict detection */
+	sector_t sector;		/* start sector of the interval */
+	unsigned int size;		/* size in bytes */
+	sector_t end;			/* highest interval end in subtree */
+	unsigned int local:1		/* local or remote request? */;
+	unsigned int waiting:1;		/* someone is waiting for completion */
+	unsigned int completed:1;	/* this has been completed already;
+					 * ignore for conflict detection */
 };
 
 static inline void drbd_clear_interval(struct drbd_interval *i)
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 2b37744db0fa..0501ae0c517b 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -31,7 +31,7 @@
 #include <linux/module.h>
 #include <linux/jiffies.h>
 #include <linux/drbd.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <asm/types.h>
 #include <net/sock.h>
 #include <linux/ctype.h>
@@ -920,6 +920,31 @@ void drbd_gen_and_send_sync_uuid(struct drbd_peer_device *peer_device)
 	}
 }
 
+/* communicated if (agreed_features & DRBD_FF_WSAME) */
+void assign_p_sizes_qlim(struct drbd_device *device, struct p_sizes *p, struct request_queue *q)
+{
+	if (q) {
+		p->qlim->physical_block_size = cpu_to_be32(queue_physical_block_size(q));
+		p->qlim->logical_block_size = cpu_to_be32(queue_logical_block_size(q));
+		p->qlim->alignment_offset = cpu_to_be32(queue_alignment_offset(q));
+		p->qlim->io_min = cpu_to_be32(queue_io_min(q));
+		p->qlim->io_opt = cpu_to_be32(queue_io_opt(q));
+		p->qlim->discard_enabled = blk_queue_discard(q);
+		p->qlim->discard_zeroes_data = queue_discard_zeroes_data(q);
+		p->qlim->write_same_capable = !!q->limits.max_write_same_sectors;
+	} else {
+		q = device->rq_queue;
+		p->qlim->physical_block_size = cpu_to_be32(queue_physical_block_size(q));
+		p->qlim->logical_block_size = cpu_to_be32(queue_logical_block_size(q));
+		p->qlim->alignment_offset = 0;
+		p->qlim->io_min = cpu_to_be32(queue_io_min(q));
+		p->qlim->io_opt = cpu_to_be32(queue_io_opt(q));
+		p->qlim->discard_enabled = 0;
+		p->qlim->discard_zeroes_data = 0;
+		p->qlim->write_same_capable = 0;
+	}
+}
+
 int drbd_send_sizes(struct drbd_peer_device *peer_device, int trigger_reply, enum dds_flags flags)
 {
 	struct drbd_device *device = peer_device->device;
@@ -928,29 +953,37 @@ int drbd_send_sizes(struct drbd_peer_device *peer_device, int trigger_reply, enu
 	sector_t d_size, u_size;
 	int q_order_type;
 	unsigned int max_bio_size;
+	unsigned int packet_size;
+
+	sock = &peer_device->connection->data;
+	p = drbd_prepare_command(peer_device, sock);
+	if (!p)
+		return -EIO;
 
+	packet_size = sizeof(*p);
+	if (peer_device->connection->agreed_features & DRBD_FF_WSAME)
+		packet_size += sizeof(p->qlim[0]);
+
+	memset(p, 0, packet_size);
 	if (get_ldev_if_state(device, D_NEGOTIATING)) {
-		D_ASSERT(device, device->ldev->backing_bdev);
+		struct request_queue *q = bdev_get_queue(device->ldev->backing_bdev);
 		d_size = drbd_get_max_capacity(device->ldev);
 		rcu_read_lock();
 		u_size = rcu_dereference(device->ldev->disk_conf)->disk_size;
 		rcu_read_unlock();
 		q_order_type = drbd_queue_order_type(device);
-		max_bio_size = queue_max_hw_sectors(device->ldev->backing_bdev->bd_disk->queue) << 9;
+		max_bio_size = queue_max_hw_sectors(q) << 9;
 		max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE);
+		assign_p_sizes_qlim(device, p, q);
 		put_ldev(device);
 	} 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 */
+		assign_p_sizes_qlim(device, p, NULL);
 	}
 
-	sock = &peer_device->connection->data;
-	p = drbd_prepare_command(peer_device, sock);
-	if (!p)
-		return -EIO;
-
 	if (peer_device->connection->agreed_pro_version <= 94)
 		max_bio_size = min(max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
 	else if (peer_device->connection->agreed_pro_version < 100)
@@ -962,7 +995,8 @@ int drbd_send_sizes(struct drbd_peer_device *peer_device, int trigger_reply, enu
 	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(peer_device, sock, P_SIZES, sizeof(*p), NULL, 0);
+
+	return drbd_send_command(peer_device, sock, P_SIZES, packet_size, NULL, 0);
 }
 
 /**
@@ -1377,6 +1411,22 @@ int drbd_send_ack_ex(struct drbd_peer_device *peer_device, enum drbd_packet cmd,
 			      cpu_to_be64(block_id));
 }
 
+int drbd_send_rs_deallocated(struct drbd_peer_device *peer_device,
+			     struct drbd_peer_request *peer_req)
+{
+	struct drbd_socket *sock;
+	struct p_block_desc *p;
+
+	sock = &peer_device->connection->data;
+	p = drbd_prepare_command(peer_device, sock);
+	if (!p)
+		return -EIO;
+	p->sector = cpu_to_be64(peer_req->i.sector);
+	p->blksize = cpu_to_be32(peer_req->i.size);
+	p->pad = 0;
+	return drbd_send_command(peer_device, sock, P_RS_DEALLOCATED, sizeof(*p), NULL, 0);
+}
+
 int drbd_send_drequest(struct drbd_peer_device *peer_device, int cmd,
 		       sector_t sector, int size, u64 block_id)
 {
@@ -1561,6 +1611,9 @@ static int _drbd_send_bio(struct drbd_peer_device *peer_device, struct bio *bio)
 					 ? 0 : MSG_MORE);
 		if (err)
 			return err;
+		/* REQ_OP_WRITE_SAME has only one segment */
+		if (bio_op(bio) == REQ_OP_WRITE_SAME)
+			break;
 	}
 	return 0;
 }
@@ -1579,6 +1632,9 @@ static int _drbd_send_zc_bio(struct drbd_peer_device *peer_device, struct bio *b
 				      bio_iter_last(bvec, iter) ? 0 : MSG_MORE);
 		if (err)
 			return err;
+		/* REQ_OP_WRITE_SAME has only one segment */
+		if (bio_op(bio) == REQ_OP_WRITE_SAME)
+			break;
 	}
 	return 0;
 }
@@ -1610,6 +1666,7 @@ static u32 bio_flags_to_wire(struct drbd_connection *connection,
 		return  (bio->bi_rw & REQ_SYNC ? DP_RW_SYNC : 0) |
 			(bio->bi_rw & REQ_FUA ? DP_FUA : 0) |
 			(bio->bi_rw & REQ_PREFLUSH ? DP_FLUSH : 0) |
+			(bio_op(bio) == REQ_OP_WRITE_SAME ? DP_WSAME : 0) |
 			(bio_op(bio) == REQ_OP_DISCARD ? DP_DISCARD : 0);
 	else
 		return bio->bi_rw & REQ_SYNC ? DP_RW_SYNC : 0;
@@ -1623,6 +1680,8 @@ int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *
 	struct drbd_device *device = peer_device->device;
 	struct drbd_socket *sock;
 	struct p_data *p;
+	struct p_wsame *wsame = NULL;
+	void *digest_out;
 	unsigned int dp_flags = 0;
 	int digest_size;
 	int err;
@@ -1658,12 +1717,29 @@ int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *
 		err = __send_command(peer_device->connection, device->vnr, sock, P_TRIM, sizeof(*t), NULL, 0);
 		goto out;
 	}
+	if (dp_flags & DP_WSAME) {
+		/* this will only work if DRBD_FF_WSAME is set AND the
+		 * handshake agreed that all nodes and backend devices are
+		 * WRITE_SAME capable and agree on logical_block_size */
+		wsame = (struct p_wsame*)p;
+		digest_out = wsame + 1;
+		wsame->size = cpu_to_be32(req->i.size);
+	} else
+		digest_out = p + 1;
 
 	/* our digest is still only over the payload.
 	 * TRIM does not carry any payload. */
 	if (digest_size)
-		drbd_csum_bio(peer_device->connection->integrity_tfm, req->master_bio, p + 1);
-	err = __send_command(peer_device->connection, device->vnr, sock, P_DATA, sizeof(*p) + digest_size, NULL, req->i.size);
+		drbd_csum_bio(peer_device->connection->integrity_tfm, req->master_bio, digest_out);
+	if (wsame) {
+		err =
+		    __send_command(peer_device->connection, device->vnr, sock, P_WSAME,
+				   sizeof(*wsame) + digest_size, NULL,
+				   bio_iovec(req->master_bio).bv_len);
+	} else
+		err =
+		    __send_command(peer_device->connection, device->vnr, sock, P_DATA,
+				   sizeof(*p) + digest_size, NULL, req->i.size);
 	if (!err) {
 		/* For protocol A, we have to memcpy the payload into
 		 * socket buffers, as we may complete right away
@@ -3507,7 +3583,12 @@ static int w_bitmap_io(struct drbd_work *w, int unused)
 	struct bm_io_work *work = &device->bm_io_work;
 	int rv = -EIO;
 
-	D_ASSERT(device, atomic_read(&device->ap_bio_cnt) == 0);
+	if (work->flags != BM_LOCKED_CHANGE_ALLOWED) {
+		int cnt = atomic_read(&device->ap_bio_cnt);
+		if (cnt)
+			drbd_err(device, "FIXME: ap_bio_cnt %d, expected 0; queued for '%s'\n",
+					cnt, work->why);
+	}
 
 	if (get_ldev(device)) {
 		drbd_bm_lock(device, work->why, work->flags);
@@ -3587,18 +3668,20 @@ void drbd_queue_bitmap_io(struct drbd_device *device,
 int drbd_bitmap_io(struct drbd_device *device, int (*io_fn)(struct drbd_device *),
 		char *why, enum bm_flag flags)
 {
+	/* Only suspend io, if some operation is supposed to be locked out */
+	const bool do_suspend_io = flags & (BM_DONT_CLEAR|BM_DONT_SET|BM_DONT_TEST);
 	int rv;
 
 	D_ASSERT(device, current != first_peer_device(device)->connection->worker.task);
 
-	if ((flags & BM_LOCKED_SET_ALLOWED) == 0)
+	if (do_suspend_io)
 		drbd_suspend_io(device);
 
 	drbd_bm_lock(device, why, flags);
 	rv = io_fn(device);
 	drbd_bm_unlock(device);
 
-	if ((flags & BM_LOCKED_SET_ALLOWED) == 0)
+	if (do_suspend_io)
 		drbd_resume_io(device);
 
 	return rv;
@@ -3637,6 +3720,8 @@ const char *cmdname(enum drbd_packet cmd)
 	 * one PRO_VERSION */
 	static const char *cmdnames[] = {
 		[P_DATA]	        = "Data",
+		[P_WSAME]	        = "WriteSame",
+		[P_TRIM]	        = "Trim",
 		[P_DATA_REPLY]	        = "DataReply",
 		[P_RS_DATA_REPLY]	= "RSDataReply",
 		[P_BARRIER]	        = "Barrier",
@@ -3681,6 +3766,8 @@ const char *cmdname(enum drbd_packet cmd)
 		[P_CONN_ST_CHG_REPLY]	= "conn_st_chg_reply",
 		[P_RETRY_WRITE]		= "retry_write",
 		[P_PROTOCOL_UPDATE]	= "protocol_update",
+		[P_RS_THIN_REQ]         = "rs_thin_req",
+		[P_RS_DEALLOCATED]      = "rs_deallocated",
 
 		/* enum drbd_packet, but not commands - obsoleted flags:
 		 *	P_MAY_IGNORE
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 0bac9c8246bc..f35db29cac76 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -343,7 +343,7 @@ int drbd_khelper(struct drbd_device *device, char *cmd)
 			 (char[20]) { }, /* address family */
 			 (char[60]) { }, /* address */
 			NULL };
-	char mb[12];
+	char mb[14];
 	char *argv[] = {usermode_helper, cmd, mb, NULL };
 	struct drbd_connection *connection = first_peer_device(device)->connection;
 	struct sib_info sib;
@@ -352,7 +352,7 @@ int drbd_khelper(struct drbd_device *device, char *cmd)
 	if (current == connection->worker.task)
 		set_bit(CALLBACK_PENDING, &connection->flags);
 
-	snprintf(mb, 12, "minor-%d", device_to_minor(device));
+	snprintf(mb, 14, "minor-%d", device_to_minor(device));
 	setup_khelper_env(connection, envp);
 
 	/* The helper may take some time.
@@ -387,7 +387,7 @@ int drbd_khelper(struct drbd_device *device, char *cmd)
 	return ret;
 }
 
-static int conn_khelper(struct drbd_connection *connection, char *cmd)
+enum drbd_peer_state conn_khelper(struct drbd_connection *connection, char *cmd)
 {
 	char *envp[] = { "HOME=/",
 			"TERM=linux",
@@ -442,19 +442,17 @@ static enum drbd_fencing_p highest_fencing_policy(struct drbd_connection *connec
 	}
 	rcu_read_unlock();
 
-	if (fp == FP_NOT_AVAIL) {
-		/* IO Suspending works on the whole resource.
-		   Do it only for one device. */
-		vnr = 0;
-		peer_device = idr_get_next(&connection->peer_devices, &vnr);
-		drbd_change_state(peer_device->device, CS_VERBOSE | CS_HARD, NS(susp_fen, 0));
-	}
-
 	return fp;
 }
 
+static bool resource_is_supended(struct drbd_resource *resource)
+{
+	return resource->susp || resource->susp_fen || resource->susp_nod;
+}
+
 bool conn_try_outdate_peer(struct drbd_connection *connection)
 {
+	struct drbd_resource * const resource = connection->resource;
 	unsigned int connect_cnt;
 	union drbd_state mask = { };
 	union drbd_state val = { };
@@ -462,21 +460,41 @@ bool conn_try_outdate_peer(struct drbd_connection *connection)
 	char *ex_to_string;
 	int r;
 
-	spin_lock_irq(&connection->resource->req_lock);
+	spin_lock_irq(&resource->req_lock);
 	if (connection->cstate >= C_WF_REPORT_PARAMS) {
 		drbd_err(connection, "Expected cstate < C_WF_REPORT_PARAMS\n");
-		spin_unlock_irq(&connection->resource->req_lock);
+		spin_unlock_irq(&resource->req_lock);
 		return false;
 	}
 
 	connect_cnt = connection->connect_cnt;
-	spin_unlock_irq(&connection->resource->req_lock);
+	spin_unlock_irq(&resource->req_lock);
 
 	fp = highest_fencing_policy(connection);
 	switch (fp) {
 	case FP_NOT_AVAIL:
 		drbd_warn(connection, "Not fencing peer, I'm not even Consistent myself.\n");
-		goto out;
+		spin_lock_irq(&resource->req_lock);
+		if (connection->cstate < C_WF_REPORT_PARAMS) {
+			_conn_request_state(connection,
+					    (union drbd_state) { { .susp_fen = 1 } },
+					    (union drbd_state) { { .susp_fen = 0 } },
+					    CS_VERBOSE | CS_HARD | CS_DC_SUSP);
+			/* We are no longer suspended due to the fencing policy.
+			 * We may still be suspended due to the on-no-data-accessible policy.
+			 * If that was OND_IO_ERROR, fail pending requests. */
+			if (!resource_is_supended(resource))
+				_tl_restart(connection, CONNECTION_LOST_WHILE_PENDING);
+		}
+		/* Else: in case we raced with a connection handshake,
+		 * let the handshake figure out if we maybe can RESEND,
+		 * and do not resume/fail pending requests here.
+		 * Worst case is we stay suspended for now, which may be
+		 * resolved by either re-establishing the replication link, or
+		 * the next link failure, or eventually the administrator.  */
+		spin_unlock_irq(&resource->req_lock);
+		return false;
+
 	case FP_DONT_CARE:
 		return true;
 	default: ;
@@ -485,17 +503,17 @@ bool conn_try_outdate_peer(struct drbd_connection *connection)
 	r = conn_khelper(connection, "fence-peer");
 
 	switch ((r>>8) & 0xff) {
-	case 3: /* peer is inconsistent */
+	case P_INCONSISTENT: /* peer is inconsistent */
 		ex_to_string = "peer is inconsistent or worse";
 		mask.pdsk = D_MASK;
 		val.pdsk = D_INCONSISTENT;
 		break;
-	case 4: /* peer got outdated, or was already outdated */
+	case P_OUTDATED: /* peer got outdated, or was already outdated */
 		ex_to_string = "peer was fenced";
 		mask.pdsk = D_MASK;
 		val.pdsk = D_OUTDATED;
 		break;
-	case 5: /* peer was down */
+	case P_DOWN: /* peer was down */
 		if (conn_highest_disk(connection) == D_UP_TO_DATE) {
 			/* we will(have) create(d) a new UUID anyways... */
 			ex_to_string = "peer is unreachable, assumed to be dead";
@@ -505,7 +523,7 @@ bool conn_try_outdate_peer(struct drbd_connection *connection)
 			ex_to_string = "peer unreachable, doing nothing since disk != UpToDate";
 		}
 		break;
-	case 6: /* Peer is primary, voluntarily outdate myself.
+	case P_PRIMARY: /* Peer is primary, voluntarily outdate myself.
 		 * This is useful when an unconnected R_SECONDARY is asked to
 		 * become R_PRIMARY, but finds the other peer being active. */
 		ex_to_string = "peer is active";
@@ -513,7 +531,9 @@ bool conn_try_outdate_peer(struct drbd_connection *connection)
 		mask.disk = D_MASK;
 		val.disk = D_OUTDATED;
 		break;
-	case 7:
+	case P_FENCING:
+		/* THINK: do we need to handle this
+		 * like case 4, or more like case 5? */
 		if (fp != FP_STONITH)
 			drbd_err(connection, "fence-peer() = 7 && fencing != Stonith !!!\n");
 		ex_to_string = "peer was stonithed";
@@ -529,13 +549,11 @@ bool conn_try_outdate_peer(struct drbd_connection *connection)
 	drbd_info(connection, "fence-peer helper returned %d (%s)\n",
 		  (r>>8) & 0xff, ex_to_string);
 
- out:
-
 	/* Not using
 	   conn_request_state(connection, mask, val, CS_VERBOSE);
 	   here, because we might were able to re-establish the connection in the
 	   meantime. */
-	spin_lock_irq(&connection->resource->req_lock);
+	spin_lock_irq(&resource->req_lock);
 	if (connection->cstate < C_WF_REPORT_PARAMS && !test_bit(STATE_SENT, &connection->flags)) {
 		if (connection->connect_cnt != connect_cnt)
 			/* In case the connection was established and droped
@@ -544,7 +562,7 @@ bool conn_try_outdate_peer(struct drbd_connection *connection)
 		else
 			_conn_request_state(connection, mask, val, CS_VERBOSE);
 	}
-	spin_unlock_irq(&connection->resource->req_lock);
+	spin_unlock_irq(&resource->req_lock);
 
 	return conn_highest_pdsk(connection) <= D_OUTDATED;
 }
@@ -1154,51 +1172,160 @@ static int drbd_check_al_size(struct drbd_device *device, struct disk_conf *dc)
 	return 0;
 }
 
+static void blk_queue_discard_granularity(struct request_queue *q, unsigned int granularity)
+{
+	q->limits.discard_granularity = granularity;
+}
+
+static unsigned int drbd_max_discard_sectors(struct drbd_connection *connection)
+{
+	/* when we introduced REQ_WRITE_SAME support, we also bumped
+	 * our maximum supported batch bio size used for discards. */
+	if (connection->agreed_features & DRBD_FF_WSAME)
+		return DRBD_MAX_BBIO_SECTORS;
+	/* before, with DRBD <= 8.4.6, we only allowed up to one AL_EXTENT_SIZE. */
+	return AL_EXTENT_SIZE >> 9;
+}
+
+static void decide_on_discard_support(struct drbd_device *device,
+			struct request_queue *q,
+			struct request_queue *b,
+			bool discard_zeroes_if_aligned)
+{
+	/* q = drbd device queue (device->rq_queue)
+	 * b = backing device queue (device->ldev->backing_bdev->bd_disk->queue),
+	 *     or NULL if diskless
+	 */
+	struct drbd_connection *connection = first_peer_device(device)->connection;
+	bool can_do = b ? blk_queue_discard(b) : true;
+
+	if (can_do && b && !b->limits.discard_zeroes_data && !discard_zeroes_if_aligned) {
+		can_do = false;
+		drbd_info(device, "discard_zeroes_data=0 and discard_zeroes_if_aligned=no: disabling discards\n");
+	}
+	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_TRIM)) {
+		can_do = false;
+		drbd_info(connection, "peer DRBD too old, does not support TRIM: disabling discards\n");
+	}
+	if (can_do) {
+		/* We don't care for the granularity, really.
+		 * Stacking limits below should fix it for the local
+		 * device.  Whether or not it is a suitable granularity
+		 * on the remote device is not our problem, really. If
+		 * you care, you need to use devices with similar
+		 * topology on all peers. */
+		blk_queue_discard_granularity(q, 512);
+		q->limits.max_discard_sectors = drbd_max_discard_sectors(connection);
+		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+	} else {
+		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
+		blk_queue_discard_granularity(q, 0);
+		q->limits.max_discard_sectors = 0;
+	}
+}
+
+static void fixup_discard_if_not_supported(struct request_queue *q)
+{
+	/* To avoid confusion, if this queue does not support discard, clear
+	 * max_discard_sectors, which is what lsblk -D reports to the user.
+	 * Older kernels got this wrong in "stack limits".
+	 * */
+	if (!blk_queue_discard(q)) {
+		blk_queue_max_discard_sectors(q, 0);
+		blk_queue_discard_granularity(q, 0);
+	}
+}
+
+static void decide_on_write_same_support(struct drbd_device *device,
+			struct request_queue *q,
+			struct request_queue *b, struct o_qlim *o)
+{
+	struct drbd_peer_device *peer_device = first_peer_device(device);
+	struct drbd_connection *connection = peer_device->connection;
+	bool can_do = b ? b->limits.max_write_same_sectors : true;
+
+	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_WSAME)) {
+		can_do = false;
+		drbd_info(peer_device, "peer does not support WRITE_SAME\n");
+	}
+
+	if (o) {
+		/* logical block size; queue_logical_block_size(NULL) is 512 */
+		unsigned int peer_lbs = be32_to_cpu(o->logical_block_size);
+		unsigned int me_lbs_b = queue_logical_block_size(b);
+		unsigned int me_lbs = queue_logical_block_size(q);
+
+		if (me_lbs_b != me_lbs) {
+			drbd_warn(device,
+				"logical block size of local backend does not match (drbd:%u, backend:%u); was this a late attach?\n",
+				me_lbs, me_lbs_b);
+			/* rather disable write same than trigger some BUG_ON later in the scsi layer. */
+			can_do = false;
+		}
+		if (me_lbs_b != peer_lbs) {
+			drbd_warn(peer_device, "logical block sizes do not match (me:%u, peer:%u); this may cause problems.\n",
+				me_lbs, peer_lbs);
+			if (can_do) {
+				drbd_dbg(peer_device, "logical block size mismatch: WRITE_SAME disabled.\n");
+				can_do = false;
+			}
+			me_lbs = max(me_lbs, me_lbs_b);
+			/* We cannot change the logical block size of an in-use queue.
+			 * We can only hope that access happens to be properly aligned.
+			 * If not, the peer will likely produce an IO error, and detach. */
+			if (peer_lbs > me_lbs) {
+				if (device->state.role != R_PRIMARY) {
+					blk_queue_logical_block_size(q, peer_lbs);
+					drbd_warn(peer_device, "logical block size set to %u\n", peer_lbs);
+				} else {
+					drbd_warn(peer_device,
+						"current Primary must NOT adjust logical block size (%u -> %u); hope for the best.\n",
+						me_lbs, peer_lbs);
+				}
+			}
+		}
+		if (can_do && !o->write_same_capable) {
+			/* If we introduce an open-coded write-same loop on the receiving side,
+			 * the peer would present itself as "capable". */
+			drbd_dbg(peer_device, "WRITE_SAME disabled (peer device not capable)\n");
+			can_do = false;
+		}
+	}
+
+	blk_queue_max_write_same_sectors(q, can_do ? DRBD_MAX_BBIO_SECTORS : 0);
+}
+
 static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backing_dev *bdev,
-				   unsigned int max_bio_size)
+				   unsigned int max_bio_size, struct o_qlim *o)
 {
 	struct request_queue * const q = device->rq_queue;
 	unsigned int max_hw_sectors = max_bio_size >> 9;
 	unsigned int max_segments = 0;
 	struct request_queue *b = NULL;
+	struct disk_conf *dc;
+	bool discard_zeroes_if_aligned = true;
 
 	if (bdev) {
 		b = bdev->backing_bdev->bd_disk->queue;
 
 		max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);
 		rcu_read_lock();
-		max_segments = rcu_dereference(device->ldev->disk_conf)->max_bio_bvecs;
+		dc = rcu_dereference(device->ldev->disk_conf);
+		max_segments = dc->max_bio_bvecs;
+		discard_zeroes_if_aligned = dc->discard_zeroes_if_aligned;
 		rcu_read_unlock();
 
 		blk_set_stacking_limits(&q->limits);
-		blk_queue_max_write_same_sectors(q, 0);
 	}
 
-	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_SIZE-1);
+	decide_on_discard_support(device, q, b, discard_zeroes_if_aligned);
+	decide_on_write_same_support(device, q, b, o);
 
 	if (b) {
-		struct drbd_connection *connection = first_peer_device(device)->connection;
-
-		blk_queue_max_discard_sectors(q, DRBD_MAX_DISCARD_SECTORS);
-
-		if (blk_queue_discard(b) &&
-		    (connection->cstate < C_CONNECTED || connection->agreed_features & FF_TRIM)) {
-			/* We don't care, stacking below should fix it for the local device.
-			 * Whether or not it is a suitable granularity on the remote device
-			 * is not our problem, really. If you care, you need to
-			 * use devices with similar topology on all peers. */
-			q->limits.discard_granularity = 512;
-			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
-		} else {
-			blk_queue_max_discard_sectors(q, 0);
-			queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
-			q->limits.discard_granularity = 0;
-		}
-
 		blk_queue_stack_limits(q, b);
 
 		if (q->backing_dev_info.ra_pages != b->backing_dev_info.ra_pages) {
@@ -1208,15 +1335,10 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
 			q->backing_dev_info.ra_pages = b->backing_dev_info.ra_pages;
 		}
 	}
-	/* To avoid confusion, if this queue does not support discard, clear
-	 * max_discard_sectors, which is what lsblk -D reports to the user.  */
-	if (!blk_queue_discard(q)) {
-		blk_queue_max_discard_sectors(q, 0);
-		q->limits.discard_granularity = 0;
-	}
+	fixup_discard_if_not_supported(q);
 }
 
-void drbd_reconsider_max_bio_size(struct drbd_device *device, struct drbd_backing_dev *bdev)
+void drbd_reconsider_queue_parameters(struct drbd_device *device, struct drbd_backing_dev *bdev, struct o_qlim *o)
 {
 	unsigned int now, new, local, peer;
 
@@ -1259,7 +1381,7 @@ void drbd_reconsider_max_bio_size(struct drbd_device *device, struct drbd_backin
 	if (new != now)
 		drbd_info(device, "max BIO size = %u\n", new);
 
-	drbd_setup_queue_param(device, bdev, new);
+	drbd_setup_queue_param(device, bdev, new, o);
 }
 
 /* Starts the worker thread */
@@ -1348,6 +1470,43 @@ static bool write_ordering_changed(struct disk_conf *a, struct disk_conf *b)
 		a->disk_drain != b->disk_drain;
 }
 
+static void sanitize_disk_conf(struct drbd_device *device, struct disk_conf *disk_conf,
+			       struct drbd_backing_dev *nbc)
+{
+	struct request_queue * const q = nbc->backing_bdev->bd_disk->queue;
+
+	if (disk_conf->al_extents < DRBD_AL_EXTENTS_MIN)
+		disk_conf->al_extents = DRBD_AL_EXTENTS_MIN;
+	if (disk_conf->al_extents > drbd_al_extents_max(nbc))
+		disk_conf->al_extents = drbd_al_extents_max(nbc);
+
+	if (!blk_queue_discard(q)
+	    || (!q->limits.discard_zeroes_data && !disk_conf->discard_zeroes_if_aligned)) {
+		if (disk_conf->rs_discard_granularity) {
+			disk_conf->rs_discard_granularity = 0; /* disable feature */
+			drbd_info(device, "rs_discard_granularity feature disabled\n");
+		}
+	}
+
+	if (disk_conf->rs_discard_granularity) {
+		int orig_value = disk_conf->rs_discard_granularity;
+		int remainder;
+
+		if (q->limits.discard_granularity > disk_conf->rs_discard_granularity)
+			disk_conf->rs_discard_granularity = q->limits.discard_granularity;
+
+		remainder = disk_conf->rs_discard_granularity % q->limits.discard_granularity;
+		disk_conf->rs_discard_granularity += remainder;
+
+		if (disk_conf->rs_discard_granularity > q->limits.max_discard_sectors << 9)
+			disk_conf->rs_discard_granularity = q->limits.max_discard_sectors << 9;
+
+		if (disk_conf->rs_discard_granularity != orig_value)
+			drbd_info(device, "rs_discard_granularity changed to %d\n",
+				  disk_conf->rs_discard_granularity);
+	}
+}
+
 int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
 {
 	struct drbd_config_context adm_ctx;
@@ -1395,10 +1554,7 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
 	if (!expect(new_disk_conf->resync_rate >= 1))
 		new_disk_conf->resync_rate = 1;
 
-	if (new_disk_conf->al_extents < DRBD_AL_EXTENTS_MIN)
-		new_disk_conf->al_extents = DRBD_AL_EXTENTS_MIN;
-	if (new_disk_conf->al_extents > drbd_al_extents_max(device->ldev))
-		new_disk_conf->al_extents = drbd_al_extents_max(device->ldev);
+	sanitize_disk_conf(device, new_disk_conf, device->ldev);
 
 	if (new_disk_conf->c_plan_ahead > DRBD_C_PLAN_AHEAD_MAX)
 		new_disk_conf->c_plan_ahead = DRBD_C_PLAN_AHEAD_MAX;
@@ -1457,6 +1613,9 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
 	if (write_ordering_changed(old_disk_conf, new_disk_conf))
 		drbd_bump_write_ordering(device->resource, NULL, WO_BDEV_FLUSH);
 
+	if (old_disk_conf->discard_zeroes_if_aligned != new_disk_conf->discard_zeroes_if_aligned)
+		drbd_reconsider_queue_parameters(device, device->ldev, NULL);
+
 	drbd_md_sync(device);
 
 	if (device->state.conn >= C_CONNECTED) {
@@ -1693,10 +1852,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 	if (retcode != NO_ERROR)
 		goto fail;
 
-	if (new_disk_conf->al_extents < DRBD_AL_EXTENTS_MIN)
-		new_disk_conf->al_extents = DRBD_AL_EXTENTS_MIN;
-	if (new_disk_conf->al_extents > drbd_al_extents_max(nbc))
-		new_disk_conf->al_extents = drbd_al_extents_max(nbc);
+	sanitize_disk_conf(device, new_disk_conf, nbc);
 
 	if (drbd_get_max_capacity(nbc) < new_disk_conf->disk_size) {
 		drbd_err(device, "max capacity %llu smaller than disk size %llu\n",
@@ -1838,7 +1994,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 	device->read_cnt = 0;
 	device->writ_cnt = 0;
 
-	drbd_reconsider_max_bio_size(device, device->ldev);
+	drbd_reconsider_queue_parameters(device, device->ldev, NULL);
 
 	/* If I am currently not R_PRIMARY,
 	 * but meta data primary indicator is set,
diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c
index 6537b25db9c1..be2b93fd2c11 100644
--- a/drivers/block/drbd/drbd_proc.c
+++ b/drivers/block/drbd/drbd_proc.c
@@ -25,7 +25,7 @@
 
 #include <linux/module.h>
 
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/proc_fs.h>
@@ -122,18 +122,18 @@ static void drbd_syncer_progress(struct drbd_device *device, struct seq_file *se
 
 	x = res/50;
 	y = 20-x;
-	seq_printf(seq, "\t[");
+	seq_puts(seq, "\t[");
 	for (i = 1; i < x; i++)
-		seq_printf(seq, "=");
-	seq_printf(seq, ">");
+		seq_putc(seq, '=');
+	seq_putc(seq, '>');
 	for (i = 0; i < y; i++)
 		seq_printf(seq, ".");
-	seq_printf(seq, "] ");
+	seq_puts(seq, "] ");
 
 	if (state.conn == C_VERIFY_S || state.conn == C_VERIFY_T)
-		seq_printf(seq, "verified:");
+		seq_puts(seq, "verified:");
 	else
-		seq_printf(seq, "sync'ed:");
+		seq_puts(seq, "sync'ed:");
 	seq_printf(seq, "%3u.%u%% ", res / 10, res % 10);
 
 	/* if more than a few GB, display in MB */
@@ -146,7 +146,7 @@ static void drbd_syncer_progress(struct drbd_device *device, struct seq_file *se
 			    (unsigned long) Bit2KB(rs_left),
 			    (unsigned long) Bit2KB(rs_total));
 
-	seq_printf(seq, "\n\t");
+	seq_puts(seq, "\n\t");
 
 	/* see drivers/md/md.c
 	 * We do not want to overflow, so the order of operands and
@@ -175,9 +175,9 @@ static void drbd_syncer_progress(struct drbd_device *device, struct seq_file *se
 		rt / 3600, (rt % 3600) / 60, rt % 60);
 
 	dbdt = Bit2KB(db/dt);
-	seq_printf(seq, " speed: ");
+	seq_puts(seq, " speed: ");
 	seq_printf_with_thousands_grouping(seq, dbdt);
-	seq_printf(seq, " (");
+	seq_puts(seq, " (");
 	/* ------------------------- ~3s average ------------------------ */
 	if (proc_details >= 1) {
 		/* this is what drbd_rs_should_slow_down() uses */
@@ -188,7 +188,7 @@ static void drbd_syncer_progress(struct drbd_device *device, struct seq_file *se
 		db = device->rs_mark_left[i] - rs_left;
 		dbdt = Bit2KB(db/dt);
 		seq_printf_with_thousands_grouping(seq, dbdt);
-		seq_printf(seq, " -- ");
+		seq_puts(seq, " -- ");
 	}
 
 	/* --------------------- long term average ---------------------- */
@@ -200,11 +200,11 @@ static void drbd_syncer_progress(struct drbd_device *device, struct seq_file *se
 	db = rs_total - rs_left;
 	dbdt = Bit2KB(db/dt);
 	seq_printf_with_thousands_grouping(seq, dbdt);
-	seq_printf(seq, ")");
+	seq_putc(seq, ')');
 
 	if (state.conn == C_SYNC_TARGET ||
 	    state.conn == C_VERIFY_S) {
-		seq_printf(seq, " want: ");
+		seq_puts(seq, " want: ");
 		seq_printf_with_thousands_grouping(seq, device->c_sync_rate);
 	}
 	seq_printf(seq, " K/sec%s\n", stalled ? " (stalled)" : "");
@@ -231,7 +231,7 @@ static void drbd_syncer_progress(struct drbd_device *device, struct seq_file *se
 			(unsigned long long)bm_bits * BM_SECT_PER_BIT);
 		if (stop_sector != 0 && stop_sector != ULLONG_MAX)
 			seq_printf(seq, " stop sector: %llu", stop_sector);
-		seq_printf(seq, "\n");
+		seq_putc(seq, '\n');
 	}
 }
 
@@ -276,7 +276,7 @@ static int drbd_seq_show(struct seq_file *seq, void *v)
 	rcu_read_lock();
 	idr_for_each_entry(&drbd_devices, device, i) {
 		if (prev_i != i - 1)
-			seq_printf(seq, "\n");
+			seq_putc(seq, '\n');
 		prev_i = i;
 
 		state = device->state;
diff --git a/drivers/block/drbd/drbd_protocol.h b/drivers/block/drbd/drbd_protocol.h
index 129f8c76c9b1..4d296800f706 100644
--- a/drivers/block/drbd/drbd_protocol.h
+++ b/drivers/block/drbd/drbd_protocol.h
@@ -60,6 +60,15 @@ enum drbd_packet {
 	 * which is why I chose TRIM here, to disambiguate. */
 	P_TRIM                = 0x31,
 
+	/* Only use these two if both support FF_THIN_RESYNC */
+	P_RS_THIN_REQ         = 0x32, /* Request a block for resync or reply P_RS_DEALLOCATED */
+	P_RS_DEALLOCATED      = 0x33, /* Contains only zeros on sync source node */
+
+	/* REQ_WRITE_SAME.
+	 * On a receiving side without REQ_WRITE_SAME,
+	 * we may fall back to an opencoded loop instead. */
+	P_WSAME               = 0x34,
+
 	P_MAY_IGNORE	      = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
 	P_MAX_OPT_CMD	      = 0x101,
 
@@ -106,8 +115,11 @@ struct p_header100 {
 	u32	  pad;
 } __packed;
 
-/* these defines must not be changed without changing the protocol version */
-#define DP_HARDBARRIER	      1 /* depricated */
+/* These defines must not be changed without changing the protocol version.
+ * New defines may only be introduced together with protocol version bump or
+ * new protocol feature flags.
+ */
+#define DP_HARDBARRIER	      1 /* no longer used */
 #define DP_RW_SYNC	      2 /* equals REQ_SYNC    */
 #define DP_MAY_SET_IN_SYNC    4
 #define DP_UNPLUG             8 /* not used anymore   */
@@ -116,6 +128,7 @@ struct p_header100 {
 #define DP_DISCARD           64 /* equals REQ_DISCARD */
 #define DP_SEND_RECEIVE_ACK 128 /* This is a proto B write request */
 #define DP_SEND_WRITE_ACK   256 /* This is a proto C write request */
+#define DP_WSAME            512 /* equiv. REQ_WRITE_SAME */
 
 struct p_data {
 	u64	    sector;    /* 64 bits sector number */
@@ -129,6 +142,11 @@ struct p_trim {
 	u32	    size;	/* == bio->bi_size */
 } __packed;
 
+struct p_wsame {
+	struct p_data p_data;
+	u32           size;     /* == bio->bi_size */
+} __packed;
+
 /*
  * commands which share a struct:
  *  p_block_ack:
@@ -160,7 +178,23 @@ struct p_block_req {
  *   ReportParams
  */
 
-#define FF_TRIM      1
+/* supports TRIM/DISCARD on the "wire" protocol */
+#define DRBD_FF_TRIM 1
+
+/* Detect all-zeros during resync, and rather TRIM/UNMAP/DISCARD those blocks
+ * instead of fully allocate a supposedly thin volume on initial resync */
+#define DRBD_FF_THIN_RESYNC 2
+
+/* supports REQ_WRITE_SAME on the "wire" protocol.
+ * Note: this flag is overloaded,
+ * its presence also
+ *   - indicates support for 128 MiB "batch bios",
+ *     max discard size of 128 MiB
+ *     instead of 4M before that.
+ *   - indicates that we exchange additional settings in p_sizes
+ *     drbd_send_sizes()/receive_sizes()
+ */
+#define DRBD_FF_WSAME 4
 
 struct p_connection_features {
 	u32 protocol_min;
@@ -235,6 +269,40 @@ struct p_rs_uuid {
 	u64	    uuid;
 } __packed;
 
+/* optional queue_limits if (agreed_features & DRBD_FF_WSAME)
+ * see also struct queue_limits, as of late 2015 */
+struct o_qlim {
+	/* we don't need it yet, but we may as well communicate it now */
+	u32 physical_block_size;
+
+	/* so the original in struct queue_limits is unsigned short,
+	 * but I'd have to put in padding anyways. */
+	u32 logical_block_size;
+
+	/* One incoming bio becomes one DRBD request,
+	 * which may be translated to several bio on the receiving side.
+	 * We don't need to communicate chunk/boundary/segment ... limits.
+	 */
+
+	/* various IO hints may be useful with "diskless client" setups */
+	u32 alignment_offset;
+	u32 io_min;
+	u32 io_opt;
+
+	/* We may need to communicate integrity stuff at some point,
+	 * but let's not get ahead of ourselves. */
+
+	/* Backend discard capabilities.
+	 * Receiving side uses "blkdev_issue_discard()", no need to communicate
+	 * more specifics.  If the backend cannot do discards, the DRBD peer
+	 * may fall back to blkdev_issue_zeroout().
+	 */
+	u8 discard_enabled;
+	u8 discard_zeroes_data;
+	u8 write_same_capable;
+	u8 _pad;
+} __packed;
+
 struct p_sizes {
 	u64	    d_size;  /* size of disk */
 	u64	    u_size;  /* user requested size */
@@ -242,6 +310,9 @@ struct p_sizes {
 	u32	    max_bio_size;  /* Maximal size of a BIO */
 	u16	    queue_order_type;  /* not yet implemented in DRBD*/
 	u16	    dds_flags; /* use enum dds_flags here. */
+
+	/* optional queue_limits if (agreed_features & DRBD_FF_WSAME) */
+	struct o_qlim qlim[0];
 } __packed;
 
 struct p_state {
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 1ee002352ea2..df45713dfbe8 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -25,7 +25,7 @@
 
 #include <linux/module.h>
 
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <net/sock.h>
 
 #include <linux/drbd.h>
@@ -48,7 +48,7 @@
 #include "drbd_req.h"
 #include "drbd_vli.h"
 
-#define PRO_FEATURES (FF_TRIM)
+#define PRO_FEATURES (DRBD_FF_TRIM|DRBD_FF_THIN_RESYNC|DRBD_FF_WSAME)
 
 struct packet_info {
 	enum drbd_packet cmd;
@@ -361,14 +361,17 @@ You must not have the req_lock:
  drbd_wait_ee_list_empty()
 */
 
+/* normal: payload_size == request size (bi_size)
+ * w_same: payload_size == logical_block_size
+ * trim: payload_size == 0 */
 struct drbd_peer_request *
 drbd_alloc_peer_req(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
-		    unsigned int data_size, bool has_payload, gfp_t gfp_mask) __must_hold(local)
+		    unsigned int request_size, unsigned int payload_size, gfp_t gfp_mask) __must_hold(local)
 {
 	struct drbd_device *device = peer_device->device;
 	struct drbd_peer_request *peer_req;
 	struct page *page = NULL;
-	unsigned nr_pages = (data_size + PAGE_SIZE -1) >> PAGE_SHIFT;
+	unsigned nr_pages = (payload_size + PAGE_SIZE -1) >> PAGE_SHIFT;
 
 	if (drbd_insert_fault(device, DRBD_FAULT_AL_EE))
 		return NULL;
@@ -380,7 +383,7 @@ drbd_alloc_peer_req(struct drbd_peer_device *peer_device, u64 id, sector_t secto
 		return NULL;
 	}
 
-	if (has_payload && data_size) {
+	if (nr_pages) {
 		page = drbd_alloc_pages(peer_device, nr_pages,
 					gfpflags_allow_blocking(gfp_mask));
 		if (!page)
@@ -390,7 +393,7 @@ drbd_alloc_peer_req(struct drbd_peer_device *peer_device, u64 id, sector_t secto
 	memset(peer_req, 0, sizeof(*peer_req));
 	INIT_LIST_HEAD(&peer_req->w.list);
 	drbd_clear_interval(&peer_req->i);
-	peer_req->i.size = data_size;
+	peer_req->i.size = request_size;
 	peer_req->i.sector = sector;
 	peer_req->submit_jif = jiffies;
 	peer_req->peer_device = peer_device;
@@ -1204,13 +1207,84 @@ static int drbd_recv_header(struct drbd_connection *connection, struct packet_in
 	return err;
 }
 
-static void drbd_flush(struct drbd_connection *connection)
+/* This is blkdev_issue_flush, but asynchronous.
+ * We want to submit to all component volumes in parallel,
+ * then wait for all completions.
+ */
+struct issue_flush_context {
+	atomic_t pending;
+	int error;
+	struct completion done;
+};
+struct one_flush_context {
+	struct drbd_device *device;
+	struct issue_flush_context *ctx;
+};
+
+void one_flush_endio(struct bio *bio)
 {
-	int rv;
-	struct drbd_peer_device *peer_device;
-	int vnr;
+	struct one_flush_context *octx = bio->bi_private;
+	struct drbd_device *device = octx->device;
+	struct issue_flush_context *ctx = octx->ctx;
 
+	if (bio->bi_error) {
+		ctx->error = bio->bi_error;
+		drbd_info(device, "local disk FLUSH FAILED with status %d\n", bio->bi_error);
+	}
+	kfree(octx);
+	bio_put(bio);
+
+	clear_bit(FLUSH_PENDING, &device->flags);
+	put_ldev(device);
+	kref_put(&device->kref, drbd_destroy_device);
+
+	if (atomic_dec_and_test(&ctx->pending))
+		complete(&ctx->done);
+}
+
+static void submit_one_flush(struct drbd_device *device, struct issue_flush_context *ctx)
+{
+	struct bio *bio = bio_alloc(GFP_NOIO, 0);
+	struct one_flush_context *octx = kmalloc(sizeof(*octx), GFP_NOIO);
+	if (!bio || !octx) {
+		drbd_warn(device, "Could not allocate a bio, CANNOT ISSUE FLUSH\n");
+		/* FIXME: what else can I do now?  disconnecting or detaching
+		 * really does not help to improve the state of the world, either.
+		 */
+		kfree(octx);
+		if (bio)
+			bio_put(bio);
+
+		ctx->error = -ENOMEM;
+		put_ldev(device);
+		kref_put(&device->kref, drbd_destroy_device);
+		return;
+	}
+
+	octx->device = device;
+	octx->ctx = ctx;
+	bio->bi_bdev = device->ldev->backing_bdev;
+	bio->bi_private = octx;
+	bio->bi_end_io = one_flush_endio;
+	bio_set_op_attrs(bio, REQ_OP_FLUSH, WRITE_FLUSH);
+
+	device->flush_jif = jiffies;
+	set_bit(FLUSH_PENDING, &device->flags);
+	atomic_inc(&ctx->pending);
+	submit_bio(bio);
+}
+
+static void drbd_flush(struct drbd_connection *connection)
+{
 	if (connection->resource->write_ordering >= WO_BDEV_FLUSH) {
+		struct drbd_peer_device *peer_device;
+		struct issue_flush_context ctx;
+		int vnr;
+
+		atomic_set(&ctx.pending, 1);
+		ctx.error = 0;
+		init_completion(&ctx.done);
+
 		rcu_read_lock();
 		idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
 			struct drbd_device *device = peer_device->device;
@@ -1220,31 +1294,24 @@ static void drbd_flush(struct drbd_connection *connection)
 			kref_get(&device->kref);
 			rcu_read_unlock();
 
-			/* Right now, we have only this one synchronous code path
-			 * for flushes between request epochs.
-			 * We may want to make those asynchronous,
-			 * or at least parallelize the flushes to the volume devices.
-			 */
-			device->flush_jif = jiffies;
-			set_bit(FLUSH_PENDING, &device->flags);
-			rv = blkdev_issue_flush(device->ldev->backing_bdev,
-					GFP_NOIO, NULL);
-			clear_bit(FLUSH_PENDING, &device->flags);
-			if (rv) {
-				drbd_info(device, "local disk flush failed with status %d\n", rv);
-				/* would rather check on EOPNOTSUPP, but that is not reliable.
-				 * don't try again for ANY return value != 0
-				 * if (rv == -EOPNOTSUPP) */
-				drbd_bump_write_ordering(connection->resource, NULL, WO_DRAIN_IO);
-			}
-			put_ldev(device);
-			kref_put(&device->kref, drbd_destroy_device);
+			submit_one_flush(device, &ctx);
 
 			rcu_read_lock();
-			if (rv)
-				break;
 		}
 		rcu_read_unlock();
+
+		/* Do we want to add a timeout,
+		 * if disk-timeout is set? */
+		if (!atomic_dec_and_test(&ctx.pending))
+			wait_for_completion(&ctx.done);
+
+		if (ctx.error) {
+			/* would rather check on EOPNOTSUPP, but that is not reliable.
+			 * don't try again for ANY return value != 0
+			 * if (rv == -EOPNOTSUPP) */
+			/* Any error is already reported by bio_endio callback. */
+			drbd_bump_write_ordering(connection->resource, NULL, WO_DRAIN_IO);
+		}
 	}
 }
 
@@ -1379,6 +1446,120 @@ void drbd_bump_write_ordering(struct drbd_resource *resource, struct drbd_backin
 		drbd_info(resource, "Method to ensure write ordering: %s\n", write_ordering_str[resource->write_ordering]);
 }
 
+/*
+ * We *may* ignore the discard-zeroes-data setting, if so configured.
+ *
+ * Assumption is that it "discard_zeroes_data=0" is only because the backend
+ * may ignore partial unaligned discards.
+ *
+ * LVM/DM thin as of at least
+ *   LVM version:     2.02.115(2)-RHEL7 (2015-01-28)
+ *   Library version: 1.02.93-RHEL7 (2015-01-28)
+ *   Driver version:  4.29.0
+ * still behaves this way.
+ *
+ * For unaligned (wrt. alignment and granularity) or too small discards,
+ * we zero-out the initial (and/or) trailing unaligned partial chunks,
+ * but discard all the aligned full chunks.
+ *
+ * At least for LVM/DM thin, the result is effectively "discard_zeroes_data=1".
+ */
+int drbd_issue_discard_or_zero_out(struct drbd_device *device, sector_t start, unsigned int nr_sectors, bool discard)
+{
+	struct block_device *bdev = device->ldev->backing_bdev;
+	struct request_queue *q = bdev_get_queue(bdev);
+	sector_t tmp, nr;
+	unsigned int max_discard_sectors, granularity;
+	int alignment;
+	int err = 0;
+
+	if (!discard)
+		goto zero_out;
+
+	/* Zero-sector (unknown) and one-sector granularities are the same.  */
+	granularity = max(q->limits.discard_granularity >> 9, 1U);
+	alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
+
+	max_discard_sectors = min(q->limits.max_discard_sectors, (1U << 22));
+	max_discard_sectors -= max_discard_sectors % granularity;
+	if (unlikely(!max_discard_sectors))
+		goto zero_out;
+
+	if (nr_sectors < granularity)
+		goto zero_out;
+
+	tmp = start;
+	if (sector_div(tmp, granularity) != alignment) {
+		if (nr_sectors < 2*granularity)
+			goto zero_out;
+		/* start + gran - (start + gran - align) % gran */
+		tmp = start + granularity - alignment;
+		tmp = start + granularity - sector_div(tmp, granularity);
+
+		nr = tmp - start;
+		err |= blkdev_issue_zeroout(bdev, start, nr, GFP_NOIO, 0);
+		nr_sectors -= nr;
+		start = tmp;
+	}
+	while (nr_sectors >= granularity) {
+		nr = min_t(sector_t, nr_sectors, max_discard_sectors);
+		err |= blkdev_issue_discard(bdev, start, nr, GFP_NOIO, 0);
+		nr_sectors -= nr;
+		start += nr;
+	}
+ zero_out:
+	if (nr_sectors) {
+		err |= blkdev_issue_zeroout(bdev, start, nr_sectors, GFP_NOIO, 0);
+	}
+	return err != 0;
+}
+
+static bool can_do_reliable_discards(struct drbd_device *device)
+{
+	struct request_queue *q = bdev_get_queue(device->ldev->backing_bdev);
+	struct disk_conf *dc;
+	bool can_do;
+
+	if (!blk_queue_discard(q))
+		return false;
+
+	if (q->limits.discard_zeroes_data)
+		return true;
+
+	rcu_read_lock();
+	dc = rcu_dereference(device->ldev->disk_conf);
+	can_do = dc->discard_zeroes_if_aligned;
+	rcu_read_unlock();
+	return can_do;
+}
+
+static void drbd_issue_peer_discard(struct drbd_device *device, struct drbd_peer_request *peer_req)
+{
+	/* If the backend cannot discard, or does not guarantee
+	 * read-back zeroes in discarded ranges, we fall back to
+	 * zero-out.  Unless configuration specifically requested
+	 * otherwise. */
+	if (!can_do_reliable_discards(device))
+		peer_req->flags |= EE_IS_TRIM_USE_ZEROOUT;
+
+	if (drbd_issue_discard_or_zero_out(device, peer_req->i.sector,
+	    peer_req->i.size >> 9, !(peer_req->flags & EE_IS_TRIM_USE_ZEROOUT)))
+		peer_req->flags |= EE_WAS_ERROR;
+	drbd_endio_write_sec_final(peer_req);
+}
+
+static void drbd_issue_peer_wsame(struct drbd_device *device,
+				  struct drbd_peer_request *peer_req)
+{
+	struct block_device *bdev = device->ldev->backing_bdev;
+	sector_t s = peer_req->i.sector;
+	sector_t nr = peer_req->i.size >> 9;
+	if (blkdev_issue_write_same(bdev, s, nr, GFP_NOIO, peer_req->pages))
+		peer_req->flags |= EE_WAS_ERROR;
+	drbd_endio_write_sec_final(peer_req);
+}
+
+
 /**
  * drbd_submit_peer_request()
  * @device:	DRBD device.
@@ -1410,7 +1591,13 @@ int drbd_submit_peer_request(struct drbd_device *device,
 	unsigned nr_pages = (data_size + PAGE_SIZE -1) >> PAGE_SHIFT;
 	int err = -ENOMEM;
 
-	if (peer_req->flags & EE_IS_TRIM_USE_ZEROOUT) {
+	/* TRIM/DISCARD: for now, always use the helper function
+	 * blkdev_issue_zeroout(..., discard=true).
+	 * It's synchronous, but it does the right thing wrt. bio splitting.
+	 * Correctness first, performance later.  Next step is to code an
+	 * asynchronous variant of the same.
+	 */
+	if (peer_req->flags & (EE_IS_TRIM|EE_WRITE_SAME)) {
 		/* wait for all pending IO completions, before we start
 		 * zeroing things out. */
 		conn_wait_active_ee_empty(peer_req->peer_device->connection);
@@ -1418,22 +1605,22 @@ int drbd_submit_peer_request(struct drbd_device *device,
 		 * so we can find it to present it in debugfs */
 		peer_req->submit_jif = jiffies;
 		peer_req->flags |= EE_SUBMITTED;
-		spin_lock_irq(&device->resource->req_lock);
-		list_add_tail(&peer_req->w.list, &device->active_ee);
-		spin_unlock_irq(&device->resource->req_lock);
-		if (blkdev_issue_zeroout(device->ldev->backing_bdev,
-			sector, data_size >> 9, GFP_NOIO, false))
-			peer_req->flags |= EE_WAS_ERROR;
-		drbd_endio_write_sec_final(peer_req);
+
+		/* If this was a resync request from receive_rs_deallocated(),
+		 * it is already on the sync_ee list */
+		if (list_empty(&peer_req->w.list)) {
+			spin_lock_irq(&device->resource->req_lock);
+			list_add_tail(&peer_req->w.list, &device->active_ee);
+			spin_unlock_irq(&device->resource->req_lock);
+		}
+
+		if (peer_req->flags & EE_IS_TRIM)
+			drbd_issue_peer_discard(device, peer_req);
+		else /* EE_WRITE_SAME */
+			drbd_issue_peer_wsame(device, peer_req);
 		return 0;
 	}
 
-	/* Discards don't have any payload.
-	 * But the scsi layer still expects a bio_vec it can use internally,
-	 * see sd_setup_discard_cmnd() and blk_add_request_payload(). */
-	if (peer_req->flags & EE_IS_TRIM)
-		nr_pages = 1;
-
 	/* In most cases, we will only need one bio.  But in case the lower
 	 * level restrictions happen to be different at this offset on this
 	 * side than those of the sending peer, we may need to submit the
@@ -1459,11 +1646,6 @@ next_bio:
 	bios = bio;
 	++n_bios;
 
-	if (op == REQ_OP_DISCARD) {
-		bio->bi_iter.bi_size = data_size;
-		goto submit;
-	}
-
 	page_chain_for_each(page) {
 		unsigned len = min_t(unsigned, data_size, PAGE_SIZE);
 		if (!bio_add_page(bio, page, len, 0)) {
@@ -1485,7 +1667,6 @@ next_bio:
 		--nr_pages;
 	}
 	D_ASSERT(device, data_size == 0);
-submit:
 	D_ASSERT(device, page == NULL);
 
 	atomic_set(&peer_req->pending_bios, n_bios);
@@ -1609,8 +1790,26 @@ static int receive_Barrier(struct drbd_connection *connection, struct packet_inf
 	return 0;
 }
 
+/* quick wrapper in case payload size != request_size (write same) */
+static void drbd_csum_ee_size(struct crypto_ahash *h,
+			      struct drbd_peer_request *r, void *d,
+			      unsigned int payload_size)
+{
+	unsigned int tmp = r->i.size;
+	r->i.size = payload_size;
+	drbd_csum_ee(h, r, d);
+	r->i.size = tmp;
+}
+
 /* used from receive_RSDataReply (recv_resync_read)
- * and from receive_Data */
+ * and from receive_Data.
+ * data_size: actual payload ("data in")
+ * 	for normal writes that is bi_size.
+ * 	for discards, that is zero.
+ * 	for write same, it is logical_block_size.
+ * both trim and write same have the bi_size ("data len to be affected")
+ * as extra argument in the packet header.
+ */
 static struct drbd_peer_request *
 read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 	      struct packet_info *pi) __must_hold(local)
@@ -1625,6 +1824,7 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 	void *dig_vv = peer_device->connection->int_dig_vv;
 	unsigned long *data;
 	struct p_trim *trim = (pi->cmd == P_TRIM) ? pi->data : NULL;
+	struct p_trim *wsame = (pi->cmd == P_WSAME) ? pi->data : NULL;
 
 	digest_size = 0;
 	if (!trim && peer_device->connection->peer_integrity_tfm) {
@@ -1639,38 +1839,60 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 		data_size -= digest_size;
 	}
 
+	/* assume request_size == data_size, but special case trim and wsame. */
+	ds = data_size;
 	if (trim) {
-		D_ASSERT(peer_device, data_size == 0);
-		data_size = be32_to_cpu(trim->size);
+		if (!expect(data_size == 0))
+			return NULL;
+		ds = be32_to_cpu(trim->size);
+	} else if (wsame) {
+		if (data_size != queue_logical_block_size(device->rq_queue)) {
+			drbd_err(peer_device, "data size (%u) != drbd logical block size (%u)\n",
+				data_size, queue_logical_block_size(device->rq_queue));
+			return NULL;
+		}
+		if (data_size != bdev_logical_block_size(device->ldev->backing_bdev)) {
+			drbd_err(peer_device, "data size (%u) != backend logical block size (%u)\n",
+				data_size, bdev_logical_block_size(device->ldev->backing_bdev));
+			return NULL;
+		}
+		ds = be32_to_cpu(wsame->size);
 	}
 
-	if (!expect(IS_ALIGNED(data_size, 512)))
+	if (!expect(IS_ALIGNED(ds, 512)))
 		return NULL;
-	/* prepare for larger trim requests. */
-	if (!trim && !expect(data_size <= DRBD_MAX_BIO_SIZE))
+	if (trim || wsame) {
+		if (!expect(ds <= (DRBD_MAX_BBIO_SECTORS << 9)))
+			return NULL;
+	} else if (!expect(ds <= DRBD_MAX_BIO_SIZE))
 		return NULL;
 
 	/* even though we trust out peer,
 	 * we sometimes have to double check. */
-	if (sector + (data_size>>9) > capacity) {
+	if (sector + (ds>>9) > capacity) {
 		drbd_err(device, "request from peer beyond end of local disk: "
 			"capacity: %llus < sector: %llus + size: %u\n",
 			(unsigned long long)capacity,
-			(unsigned long long)sector, data_size);
+			(unsigned long long)sector, ds);
 		return NULL;
 	}
 
 	/* GFP_NOIO, because we must not cause arbitrary write-out: in a DRBD
 	 * "criss-cross" setup, that might cause write-out on some other DRBD,
 	 * which in turn might block on the other node at this very place.  */
-	peer_req = drbd_alloc_peer_req(peer_device, id, sector, data_size, trim == NULL, GFP_NOIO);
+	peer_req = drbd_alloc_peer_req(peer_device, id, sector, ds, data_size, GFP_NOIO);
 	if (!peer_req)
 		return NULL;
 
 	peer_req->flags |= EE_WRITE;
-	if (trim)
+	if (trim) {
+		peer_req->flags |= EE_IS_TRIM;
 		return peer_req;
+	}
+	if (wsame)
+		peer_req->flags |= EE_WRITE_SAME;
 
+	/* receive payload size bytes into page chain */
 	ds = data_size;
 	page = peer_req->pages;
 	page_chain_for_each(page) {
@@ -1690,7 +1912,7 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 	}
 
 	if (digest_size) {
-		drbd_csum_ee(peer_device->connection->peer_integrity_tfm, peer_req, dig_vv);
+		drbd_csum_ee_size(peer_device->connection->peer_integrity_tfm, peer_req, dig_vv, data_size);
 		if (memcmp(dig_in, dig_vv, digest_size)) {
 			drbd_err(device, "Digest integrity check FAILED: %llus +%u\n",
 				(unsigned long long)sector, data_size);
@@ -2067,13 +2289,13 @@ static inline int overlaps(sector_t s1, int l1, sector_t s2, int l2)
 static bool overlapping_resync_write(struct drbd_device *device, struct drbd_peer_request *peer_req)
 {
 	struct drbd_peer_request *rs_req;
-	bool rv = 0;
+	bool rv = false;
 
 	spin_lock_irq(&device->resource->req_lock);
 	list_for_each_entry(rs_req, &device->sync_ee, w.list) {
 		if (overlaps(peer_req->i.sector, peer_req->i.size,
 			     rs_req->i.sector, rs_req->i.size)) {
-			rv = 1;
+			rv = true;
 			break;
 		}
 	}
@@ -2354,10 +2576,6 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 	op = wire_flags_to_bio_op(dp_flags);
 	op_flags = wire_flags_to_bio_flags(dp_flags);
 	if (pi->cmd == P_TRIM) {
-		struct request_queue *q = bdev_get_queue(device->ldev->backing_bdev);
-		peer_req->flags |= EE_IS_TRIM;
-		if (!blk_queue_discard(q))
-			peer_req->flags |= EE_IS_TRIM_USE_ZEROOUT;
 		D_ASSERT(peer_device, peer_req->i.size > 0);
 		D_ASSERT(peer_device, op == REQ_OP_DISCARD);
 		D_ASSERT(peer_device, peer_req->pages == NULL);
@@ -2424,11 +2642,11 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 		update_peer_seq(peer_device, peer_seq);
 		spin_lock_irq(&device->resource->req_lock);
 	}
-	/* if we use the zeroout fallback code, we process synchronously
-	 * and we wait for all pending requests, respectively wait for
+	/* TRIM and WRITE_SAME are processed synchronously,
+	 * we wait for all pending requests, respectively wait for
 	 * active_ee to become empty in drbd_submit_peer_request();
 	 * better not add ourselves here. */
-	if ((peer_req->flags & EE_IS_TRIM_USE_ZEROOUT) == 0)
+	if ((peer_req->flags & (EE_IS_TRIM|EE_WRITE_SAME)) == 0)
 		list_add_tail(&peer_req->w.list, &device->active_ee);
 	spin_unlock_irq(&device->resource->req_lock);
 
@@ -2460,7 +2678,7 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 	}
 
 out_interrupted:
-	drbd_may_finish_epoch(connection, peer_req->epoch, EV_PUT + EV_CLEANUP);
+	drbd_may_finish_epoch(connection, peer_req->epoch, EV_PUT | EV_CLEANUP);
 	put_ldev(device);
 	drbd_free_peer_req(device, peer_req);
 	return err;
@@ -2585,6 +2803,7 @@ static int receive_DataRequest(struct drbd_connection *connection, struct packet
 		case P_DATA_REQUEST:
 			drbd_send_ack_rp(peer_device, P_NEG_DREPLY, p);
 			break;
+		case P_RS_THIN_REQ:
 		case P_RS_DATA_REQUEST:
 		case P_CSUM_RS_REQUEST:
 		case P_OV_REQUEST:
@@ -2610,7 +2829,7 @@ static int receive_DataRequest(struct drbd_connection *connection, struct packet
 	 * "criss-cross" setup, that might cause write-out on some other DRBD,
 	 * which in turn might block on the other node at this very place.  */
 	peer_req = drbd_alloc_peer_req(peer_device, p->block_id, sector, size,
-			true /* has real payload */, GFP_NOIO);
+			size, GFP_NOIO);
 	if (!peer_req) {
 		put_ldev(device);
 		return -ENOMEM;
@@ -2624,6 +2843,12 @@ static int receive_DataRequest(struct drbd_connection *connection, struct packet
 		peer_req->flags |= EE_APPLICATION;
 		goto submit;
 
+	case P_RS_THIN_REQ:
+		/* If at some point in the future we have a smart way to
+		   find out if this data block is completely deallocated,
+		   then we would do something smarter here than reading
+		   the block... */
+		peer_req->flags |= EE_RS_THIN_REQ;
 	case P_RS_DATA_REQUEST:
 		peer_req->w.cb = w_e_end_rsdata_req;
 		fault_type = DRBD_FAULT_RS_RD;
@@ -2969,7 +3194,8 @@ static void drbd_uuid_dump(struct drbd_device *device, char *text, u64 *uuid,
 -1091   requires proto 91
 -1096   requires proto 96
  */
-static int drbd_uuid_compare(struct drbd_device *const device, int *rule_nr) __must_hold(local)
+
+static int drbd_uuid_compare(struct drbd_device *const device, enum drbd_role const peer_role, int *rule_nr) __must_hold(local)
 {
 	struct drbd_peer_device *const peer_device = first_peer_device(device);
 	struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL;
@@ -3049,8 +3275,39 @@ static int drbd_uuid_compare(struct drbd_device *const device, int *rule_nr) __m
 		 * next bit (weight 2) is set when peer was primary */
 		*rule_nr = 40;
 
+		/* Neither has the "crashed primary" flag set,
+		 * only a replication link hickup. */
+		if (rct == 0)
+			return 0;
+
+		/* Current UUID equal and no bitmap uuid; does not necessarily
+		 * mean this was a "simultaneous hard crash", maybe IO was
+		 * frozen, so no UUID-bump happened.
+		 * This is a protocol change, overload DRBD_FF_WSAME as flag
+		 * for "new-enough" peer DRBD version. */
+		if (device->state.role == R_PRIMARY || peer_role == R_PRIMARY) {
+			*rule_nr = 41;
+			if (!(connection->agreed_features & DRBD_FF_WSAME)) {
+				drbd_warn(peer_device, "Equivalent unrotated UUIDs, but current primary present.\n");
+				return -(0x10000 | PRO_VERSION_MAX | (DRBD_FF_WSAME << 8));
+			}
+			if (device->state.role == R_PRIMARY && peer_role == R_PRIMARY) {
+				/* At least one has the "crashed primary" bit set,
+				 * both are primary now, but neither has rotated its UUIDs?
+				 * "Can not happen." */
+				drbd_err(peer_device, "Equivalent unrotated UUIDs, but both are primary. Can not resolve this.\n");
+				return -100;
+			}
+			if (device->state.role == R_PRIMARY)
+				return 1;
+			return -1;
+		}
+
+		/* Both are secondary.
+		 * Really looks like recovery from simultaneous hard crash.
+		 * Check which had been primary before, and arbitrate. */
 		switch (rct) {
-		case 0: /* !self_pri && !peer_pri */ return 0;
+		case 0: /* !self_pri && !peer_pri */ return 0; /* already handled */
 		case 1: /*  self_pri && !peer_pri */ return 1;
 		case 2: /* !self_pri &&  peer_pri */ return -1;
 		case 3: /*  self_pri &&  peer_pri */
@@ -3177,7 +3434,7 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device,
 	drbd_uuid_dump(device, "peer", device->p_uuid,
 		       device->p_uuid[UI_SIZE], device->p_uuid[UI_FLAGS]);
 
-	hg = drbd_uuid_compare(device, &rule_nr);
+	hg = drbd_uuid_compare(device, peer_role, &rule_nr);
 	spin_unlock_irq(&device->ldev->md.uuid_lock);
 
 	drbd_info(device, "uuid_compare()=%d by rule %d\n", hg, rule_nr);
@@ -3186,6 +3443,15 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device,
 		drbd_alert(device, "Unrelated data, aborting!\n");
 		return C_MASK;
 	}
+	if (hg < -0x10000) {
+		int proto, fflags;
+		hg = -hg;
+		proto = hg & 0xff;
+		fflags = (hg >> 8) & 0xff;
+		drbd_alert(device, "To resolve this both sides have to support at least protocol %d and feature flags 0x%x\n",
+					proto, fflags);
+		return C_MASK;
+	}
 	if (hg < -1000) {
 		drbd_alert(device, "To resolve this both sides have to support at least protocol %d\n", -hg - 1000);
 		return C_MASK;
@@ -3415,7 +3681,8 @@ static int receive_protocol(struct drbd_connection *connection, struct packet_in
 		 */
 
 		peer_integrity_tfm = crypto_alloc_ahash(integrity_alg, 0, CRYPTO_ALG_ASYNC);
-		if (!peer_integrity_tfm) {
+		if (IS_ERR(peer_integrity_tfm)) {
+			peer_integrity_tfm = NULL;
 			drbd_err(connection, "peer data-integrity-alg %s not supported\n",
 				 integrity_alg);
 			goto disconnect;
@@ -3766,6 +4033,7 @@ static int receive_sizes(struct drbd_connection *connection, struct packet_info
 	struct drbd_peer_device *peer_device;
 	struct drbd_device *device;
 	struct p_sizes *p = pi->data;
+	struct o_qlim *o = (connection->agreed_features & DRBD_FF_WSAME) ? p->qlim : NULL;
 	enum determine_dev_size dd = DS_UNCHANGED;
 	sector_t p_size, p_usize, p_csize, my_usize;
 	int ldsc = 0; /* local disk size changed */
@@ -3785,6 +4053,7 @@ static int receive_sizes(struct drbd_connection *connection, struct packet_info
 	device->p_size = p_size;
 
 	if (get_ldev(device)) {
+		sector_t new_size, cur_size;
 		rcu_read_lock();
 		my_usize = rcu_dereference(device->ldev->disk_conf)->disk_size;
 		rcu_read_unlock();
@@ -3801,11 +4070,13 @@ static int receive_sizes(struct drbd_connection *connection, struct packet_info
 
 		/* Never shrink a device with usable data during connect.
 		   But allow online shrinking if we are connected. */
-		if (drbd_new_dev_size(device, device->ldev, p_usize, 0) <
-		    drbd_get_capacity(device->this_bdev) &&
+		new_size = drbd_new_dev_size(device, device->ldev, p_usize, 0);
+		cur_size = drbd_get_capacity(device->this_bdev);
+		if (new_size < cur_size &&
 		    device->state.disk >= D_OUTDATED &&
 		    device->state.conn < C_CONNECTED) {
-			drbd_err(device, "The peer's disk size is too small!\n");
+			drbd_err(device, "The peer's disk size is too small! (%llu < %llu sectors)\n",
+					(unsigned long long)new_size, (unsigned long long)cur_size);
 			conn_request_state(peer_device->connection, NS(conn, C_DISCONNECTING), CS_HARD);
 			put_ldev(device);
 			return -EIO;
@@ -3839,14 +4110,14 @@ static int receive_sizes(struct drbd_connection *connection, struct packet_info
 	}
 
 	device->peer_max_bio_size = be32_to_cpu(p->max_bio_size);
-	/* Leave drbd_reconsider_max_bio_size() before drbd_determine_dev_size().
+	/* Leave drbd_reconsider_queue_parameters() before drbd_determine_dev_size().
 	   In case we cleared the QUEUE_FLAG_DISCARD from our queue in
-	   drbd_reconsider_max_bio_size(), we can be sure that after
+	   drbd_reconsider_queue_parameters(), we can be sure that after
 	   drbd_determine_dev_size() no REQ_DISCARDs are in the queue. */
 
 	ddsf = be16_to_cpu(p->dds_flags);
 	if (get_ldev(device)) {
-		drbd_reconsider_max_bio_size(device, device->ldev);
+		drbd_reconsider_queue_parameters(device, device->ldev, o);
 		dd = drbd_determine_dev_size(device, ddsf, NULL);
 		put_ldev(device);
 		if (dd == DS_ERROR)
@@ -3866,7 +4137,7 @@ static int receive_sizes(struct drbd_connection *connection, struct packet_info
 		 * However, if he sends a zero current size,
 		 * take his (user-capped or) backing disk size anyways.
 		 */
-		drbd_reconsider_max_bio_size(device, NULL);
+		drbd_reconsider_queue_parameters(device, NULL, o);
 		drbd_set_my_capacity(device, p_csize ?: p_usize ?: p_size);
 	}
 
@@ -4599,9 +4870,75 @@ static int receive_out_of_sync(struct drbd_connection *connection, struct packet
 	return 0;
 }
 
+static int receive_rs_deallocated(struct drbd_connection *connection, struct packet_info *pi)
+{
+	struct drbd_peer_device *peer_device;
+	struct p_block_desc *p = pi->data;
+	struct drbd_device *device;
+	sector_t sector;
+	int size, err = 0;
+
+	peer_device = conn_peer_device(connection, pi->vnr);
+	if (!peer_device)
+		return -EIO;
+	device = peer_device->device;
+
+	sector = be64_to_cpu(p->sector);
+	size = be32_to_cpu(p->blksize);
+
+	dec_rs_pending(device);
+
+	if (get_ldev(device)) {
+		struct drbd_peer_request *peer_req;
+		const int op = REQ_OP_DISCARD;
+
+		peer_req = drbd_alloc_peer_req(peer_device, ID_SYNCER, sector,
+					       size, 0, GFP_NOIO);
+		if (!peer_req) {
+			put_ldev(device);
+			return -ENOMEM;
+		}
+
+		peer_req->w.cb = e_end_resync_block;
+		peer_req->submit_jif = jiffies;
+		peer_req->flags |= EE_IS_TRIM;
+
+		spin_lock_irq(&device->resource->req_lock);
+		list_add_tail(&peer_req->w.list, &device->sync_ee);
+		spin_unlock_irq(&device->resource->req_lock);
+
+		atomic_add(pi->size >> 9, &device->rs_sect_ev);
+		err = drbd_submit_peer_request(device, peer_req, op, 0, DRBD_FAULT_RS_WR);
+
+		if (err) {
+			spin_lock_irq(&device->resource->req_lock);
+			list_del(&peer_req->w.list);
+			spin_unlock_irq(&device->resource->req_lock);
+
+			drbd_free_peer_req(device, peer_req);
+			put_ldev(device);
+			err = 0;
+			goto fail;
+		}
+
+		inc_unacked(device);
+
+		/* No put_ldev() here. Gets called in drbd_endio_write_sec_final(),
+		   as well as drbd_rs_complete_io() */
+	} else {
+	fail:
+		drbd_rs_complete_io(device, sector);
+		drbd_send_ack_ex(peer_device, P_NEG_ACK, sector, size, ID_SYNCER);
+	}
+
+	atomic_add(size >> 9, &device->rs_sect_in);
+
+	return err;
+}
+
 struct data_cmd {
 	int expect_payload;
-	size_t pkt_size;
+	unsigned int pkt_size;
 	int (*fn)(struct drbd_connection *, struct packet_info *);
 };
 
@@ -4626,11 +4963,14 @@ static struct data_cmd drbd_cmd_handler[] = {
 	[P_OV_REQUEST]      = { 0, sizeof(struct p_block_req), receive_DataRequest },
 	[P_OV_REPLY]        = { 1, sizeof(struct p_block_req), receive_DataRequest },
 	[P_CSUM_RS_REQUEST] = { 1, sizeof(struct p_block_req), receive_DataRequest },
+	[P_RS_THIN_REQ]     = { 0, sizeof(struct p_block_req), receive_DataRequest },
 	[P_DELAY_PROBE]     = { 0, sizeof(struct p_delay_probe93), receive_skip },
 	[P_OUT_OF_SYNC]     = { 0, sizeof(struct p_block_desc), receive_out_of_sync },
 	[P_CONN_ST_CHG_REQ] = { 0, sizeof(struct p_req_state), receive_req_conn_state },
 	[P_PROTOCOL_UPDATE] = { 1, sizeof(struct p_protocol), receive_protocol },
 	[P_TRIM]	    = { 0, sizeof(struct p_trim), receive_Data },
+	[P_RS_DEALLOCATED]  = { 0, sizeof(struct p_block_desc), receive_rs_deallocated },
+	[P_WSAME]	    = { 1, sizeof(struct p_wsame), receive_Data },
 };
 
 static void drbdd(struct drbd_connection *connection)
@@ -4640,7 +4980,7 @@ static void drbdd(struct drbd_connection *connection)
 	int err;
 
 	while (get_t_state(&connection->receiver) == RUNNING) {
-		struct data_cmd *cmd;
+		struct data_cmd const *cmd;
 
 		drbd_thread_current_set_cpu(&connection->receiver);
 		update_receiver_timing_details(connection, drbd_recv_header);
@@ -4655,11 +4995,18 @@ static void drbdd(struct drbd_connection *connection)
 		}
 
 		shs = cmd->pkt_size;
+		if (pi.cmd == P_SIZES && connection->agreed_features & DRBD_FF_WSAME)
+			shs += sizeof(struct o_qlim);
 		if (pi.size > shs && !cmd->expect_payload) {
 			drbd_err(connection, "No payload expected %s l:%d\n",
 				 cmdname(pi.cmd), pi.size);
 			goto err_out;
 		}
+		if (pi.size < shs) {
+			drbd_err(connection, "%s: unexpected packet size, expected:%d received:%d\n",
+				 cmdname(pi.cmd), (int)shs, pi.size);
+			goto err_out;
+		}
 
 		if (shs) {
 			update_receiver_timing_details(connection, drbd_recv_all_warn);
@@ -4795,9 +5142,11 @@ static int drbd_disconnected(struct drbd_peer_device *peer_device)
 
 	drbd_md_sync(device);
 
-	/* serialize with bitmap writeout triggered by the state change,
-	 * if any. */
-	wait_event(device->misc_wait, !test_bit(BITMAP_IO, &device->flags));
+	if (get_ldev(device)) {
+		drbd_bitmap_io(device, &drbd_bm_write_copy_pages,
+				"write from disconnected", BM_LOCKED_CHANGE_ALLOWED);
+		put_ldev(device);
+	}
 
 	/* tcp_close and release of sendpage pages can be deferred.  I don't
 	 * want to use SO_LINGER, because apparently it can be deferred for
@@ -4904,8 +5253,12 @@ static int drbd_do_features(struct drbd_connection *connection)
 	drbd_info(connection, "Handshake successful: "
 	     "Agreed network protocol version %d\n", connection->agreed_pro_version);
 
-	drbd_info(connection, "Agreed to%ssupport TRIM on protocol level\n",
-		  connection->agreed_features & FF_TRIM ? " " : " not ");
+	drbd_info(connection, "Feature flags enabled on protocol level: 0x%x%s%s%s.\n",
+		  connection->agreed_features,
+		  connection->agreed_features & DRBD_FF_TRIM ? " TRIM" : "",
+		  connection->agreed_features & DRBD_FF_THIN_RESYNC ? " THIN_RESYNC" : "",
+		  connection->agreed_features & DRBD_FF_WSAME ? " WRITE_SAME" :
+		  connection->agreed_features ? "" : " none");
 
 	return 1;
 
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index eef6e9575b4e..66b8e4bb74d8 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -47,8 +47,7 @@ static void _drbd_end_io_acct(struct drbd_device *device, struct drbd_request *r
 			    &device->vdisk->part0, req->start_jif);
 }
 
-static struct drbd_request *drbd_req_new(struct drbd_device *device,
-					       struct bio *bio_src)
+static struct drbd_request *drbd_req_new(struct drbd_device *device, struct bio *bio_src)
 {
 	struct drbd_request *req;
 
@@ -58,10 +57,12 @@ static struct drbd_request *drbd_req_new(struct drbd_device *device,
 	memset(req, 0, sizeof(*req));
 
 	drbd_req_make_private_bio(req, bio_src);
-	req->rq_state    = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0;
-	req->device   = device;
-	req->master_bio  = bio_src;
-	req->epoch       = 0;
+	req->rq_state = (bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0)
+		      | (bio_op(bio_src) == REQ_OP_WRITE_SAME ? RQ_WSAME : 0)
+		      | (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 0);
+	req->device = device;
+	req->master_bio = bio_src;
+	req->epoch = 0;
 
 	drbd_clear_interval(&req->i);
 	req->i.sector     = bio_src->bi_iter.bi_sector;
@@ -218,7 +219,6 @@ void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
 {
 	const unsigned s = req->rq_state;
 	struct drbd_device *device = req->device;
-	int rw;
 	int error, ok;
 
 	/* we must not complete the master bio, while it is
@@ -242,8 +242,6 @@ void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
 		return;
 	}
 
-	rw = bio_rw(req->master_bio);
-
 	/*
 	 * figure out whether to report success or failure.
 	 *
@@ -267,7 +265,7 @@ void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
 	 * epoch number.  If they match, increase the current_tle_nr,
 	 * and reset the transfer log epoch write_cnt.
 	 */
-	if (rw == WRITE &&
+	if (op_is_write(bio_op(req->master_bio)) &&
 	    req->epoch == atomic_read(&first_peer_device(device)->connection->current_tle_nr))
 		start_new_tl_epoch(first_peer_device(device)->connection);
 
@@ -284,11 +282,14 @@ void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
 	 * because no path was available, in which case
 	 * it was not even added to the transfer_log.
 	 *
-	 * READA may fail, and will not be retried.
+	 * read-ahead may fail, and will not be retried.
 	 *
 	 * WRITE should have used all available paths already.
 	 */
-	if (!ok && rw == READ && !list_empty(&req->tl_requests))
+	if (!ok &&
+	    bio_op(req->master_bio) == REQ_OP_READ &&
+	    !(req->master_bio->bi_rw & REQ_RAHEAD) &&
+	    !list_empty(&req->tl_requests))
 		req->rq_state |= RQ_POSTPONED;
 
 	if (!(req->rq_state & RQ_POSTPONED)) {
@@ -644,7 +645,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 		__drbd_chk_io_error(device, DRBD_READ_ERROR);
 		/* fall through. */
 	case READ_AHEAD_COMPLETED_WITH_ERROR:
-		/* it is legal to fail READA, no __drbd_chk_io_error in that case. */
+		/* it is legal to fail read-ahead, no __drbd_chk_io_error in that case. */
 		mod_rq_state(req, m, RQ_LOCAL_PENDING, RQ_LOCAL_COMPLETED);
 		break;
 
@@ -656,7 +657,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 		break;
 
 	case QUEUE_FOR_NET_READ:
-		/* READ or READA, and
+		/* READ, and
 		 * no local disk,
 		 * or target area marked as invalid,
 		 * or just got an io-error. */
@@ -977,16 +978,20 @@ static void complete_conflicting_writes(struct drbd_request *req)
 	sector_t sector = req->i.sector;
 	int size = req->i.size;
 
-	i = drbd_find_overlap(&device->write_requests, sector, size);
-	if (!i)
-		return;
-
 	for (;;) {
-		prepare_to_wait(&device->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
-		i = drbd_find_overlap(&device->write_requests, sector, size);
-		if (!i)
+		drbd_for_each_overlap(i, &device->write_requests, sector, size) {
+			/* Ignore, if already completed to upper layers. */
+			if (i->completed)
+				continue;
+			/* Handle the first found overlap.  After the schedule
+			 * we have to restart the tree walk. */
+			break;
+		}
+		if (!i)	/* if any */
 			break;
+
 		/* Indicate to wake up device->misc_wait on progress.  */
+		prepare_to_wait(&device->misc_wait, &wait, TASK_UNINTERRUPTIBLE);
 		i->waiting = true;
 		spin_unlock_irq(&device->resource->req_lock);
 		schedule();
@@ -995,7 +1000,7 @@ static void complete_conflicting_writes(struct drbd_request *req)
 	finish_wait(&device->misc_wait, &wait);
 }
 
-/* called within req_lock and rcu_read_lock() */
+/* called within req_lock */
 static void maybe_pull_ahead(struct drbd_device *device)
 {
 	struct drbd_connection *connection = first_peer_device(device)->connection;
@@ -1152,12 +1157,29 @@ static int drbd_process_write_request(struct drbd_request *req)
 	return remote;
 }
 
+static void drbd_process_discard_req(struct drbd_request *req)
+{
+	int err = drbd_issue_discard_or_zero_out(req->device,
+				req->i.sector, req->i.size >> 9, true);
+
+	if (err)
+		req->private_bio->bi_error = -EIO;
+	bio_endio(req->private_bio);
+}
+
 static void
 drbd_submit_req_private_bio(struct drbd_request *req)
 {
 	struct drbd_device *device = req->device;
 	struct bio *bio = req->private_bio;
-	const int rw = bio_rw(bio);
+	unsigned int type;
+
+	if (bio_op(bio) != REQ_OP_READ)
+		type = DRBD_FAULT_DT_WR;
+	else if (bio->bi_rw & REQ_RAHEAD)
+		type = DRBD_FAULT_DT_RA;
+	else
+		type = DRBD_FAULT_DT_RD;
 
 	bio->bi_bdev = device->ldev->backing_bdev;
 
@@ -1167,11 +1189,10 @@ drbd_submit_req_private_bio(struct drbd_request *req)
 	 * stable storage, and this is a WRITE, we may not even submit
 	 * this bio. */
 	if (get_ldev(device)) {
-		if (drbd_insert_fault(device,
-				      rw == WRITE ? DRBD_FAULT_DT_WR
-				    : rw == READ  ? DRBD_FAULT_DT_RD
-				    :               DRBD_FAULT_DT_RA))
+		if (drbd_insert_fault(device, type))
 			bio_io_error(bio);
+		else if (bio_op(bio) == REQ_OP_DISCARD)
+			drbd_process_discard_req(req);
 		else
 			generic_make_request(bio);
 		put_ldev(device);
@@ -1223,24 +1244,45 @@ drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long
 	/* Update disk stats */
 	_drbd_start_io_acct(device, req);
 
+	/* process discards always from our submitter thread */
+	if (bio_op(bio) & REQ_OP_DISCARD)
+		goto queue_for_submitter_thread;
+
 	if (rw == WRITE && req->private_bio && req->i.size
 	&& !test_bit(AL_SUSPENDED, &device->flags)) {
-		if (!drbd_al_begin_io_fastpath(device, &req->i)) {
-			atomic_inc(&device->ap_actlog_cnt);
-			drbd_queue_write(device, req);
-			return NULL;
-		}
+		if (!drbd_al_begin_io_fastpath(device, &req->i))
+			goto queue_for_submitter_thread;
 		req->rq_state |= RQ_IN_ACT_LOG;
 		req->in_actlog_jif = jiffies;
 	}
-
 	return req;
+
+ queue_for_submitter_thread:
+	atomic_inc(&device->ap_actlog_cnt);
+	drbd_queue_write(device, req);
+	return NULL;
+}
+
+/* Require at least one path to current data.
+ * We don't want to allow writes on C_STANDALONE D_INCONSISTENT:
+ * We would not allow to read what was written,
+ * we would not have bumped the data generation uuids,
+ * we would cause data divergence for all the wrong reasons.
+ *
+ * If we don't see at least one D_UP_TO_DATE, we will fail this request,
+ * which either returns EIO, or, if OND_SUSPEND_IO is set, suspends IO,
+ * and queues for retry later.
+ */
+static bool may_do_writes(struct drbd_device *device)
+{
+	const union drbd_dev_state s = device->state;
+	return s.disk == D_UP_TO_DATE || s.pdsk == D_UP_TO_DATE;
 }
 
 static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req)
 {
 	struct drbd_resource *resource = device->resource;
-	const int rw = bio_rw(req->master_bio);
+	const int rw = bio_data_dir(req->master_bio);
 	struct bio_and_error m = { NULL, };
 	bool no_remote = false;
 	bool submit_private_bio = false;
@@ -1270,7 +1312,7 @@ static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request
 		goto out;
 	}
 
-	/* We fail READ/READA early, if we can not serve it.
+	/* We fail READ early, if we can not serve it.
 	 * We must do this before req is registered on any lists.
 	 * Otherwise, drbd_req_complete() will queue failed READ for retry. */
 	if (rw != WRITE) {
@@ -1291,6 +1333,12 @@ static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request
 	}
 
 	if (rw == WRITE) {
+		if (req->private_bio && !may_do_writes(device)) {
+			bio_put(req->private_bio);
+			req->private_bio = NULL;
+			put_ldev(device);
+			goto nodata;
+		}
 		if (!drbd_process_write_request(req))
 			no_remote = true;
 	} else {
diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h
index bb2ef78165e5..eb49e7f2da91 100644
--- a/drivers/block/drbd/drbd_req.h
+++ b/drivers/block/drbd/drbd_req.h
@@ -206,6 +206,8 @@ enum drbd_req_state_bits {
 
 	/* Set when this is a write, clear for a read */
 	__RQ_WRITE,
+	__RQ_WSAME,
+	__RQ_UNMAP,
 
 	/* Should call drbd_al_complete_io() for this request... */
 	__RQ_IN_ACT_LOG,
@@ -241,10 +243,11 @@ enum drbd_req_state_bits {
 #define RQ_NET_OK          (1UL << __RQ_NET_OK)
 #define RQ_NET_SIS         (1UL << __RQ_NET_SIS)
 
-/* 0x1f8 */
 #define RQ_NET_MASK        (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK)
 
 #define RQ_WRITE           (1UL << __RQ_WRITE)
+#define RQ_WSAME           (1UL << __RQ_WSAME)
+#define RQ_UNMAP           (1UL << __RQ_UNMAP)
 #define RQ_IN_ACT_LOG      (1UL << __RQ_IN_ACT_LOG)
 #define RQ_POSTPONED	   (1UL << __RQ_POSTPONED)
 #define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP)
diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index 5a7ef7873b67..eea0c4aec978 100644
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -814,7 +814,7 @@ is_valid_state(struct drbd_device *device, union drbd_state ns)
 	}
 
 	if (rv <= 0)
-		/* already found a reason to abort */;
+		goto out; /* already found a reason to abort */
 	else if (ns.role == R_SECONDARY && device->open_cnt)
 		rv = SS_DEVICE_IN_USE;
 
@@ -862,6 +862,7 @@ is_valid_state(struct drbd_device *device, union drbd_state ns)
 	else if (ns.conn >= C_CONNECTED && ns.pdsk == D_UNKNOWN)
 		rv = SS_CONNECTED_OUTDATES;
 
+out:
 	rcu_read_unlock();
 
 	return rv;
@@ -906,6 +907,15 @@ is_valid_soft_transition(union drbd_state os, union drbd_state ns, struct drbd_c
 	      (ns.conn >= C_CONNECTED && os.conn == C_WF_REPORT_PARAMS)))
 		rv = SS_IN_TRANSIENT_STATE;
 
+	/* Do not promote during resync handshake triggered by "force primary".
+	 * This is a hack. It should really be rejected by the peer during the
+	 * cluster wide state change request. */
+	if (os.role != R_PRIMARY && ns.role == R_PRIMARY
+		&& ns.pdsk == D_UP_TO_DATE
+		&& ns.disk != D_UP_TO_DATE && ns.disk != D_DISKLESS
+		&& (ns.conn <= C_WF_SYNC_UUID || ns.conn != os.conn))
+			rv = SS_IN_TRANSIENT_STATE;
+
 	if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) && os.conn < C_CONNECTED)
 		rv = SS_NEED_CONNECTION;
 
@@ -1628,6 +1638,26 @@ static void broadcast_state_change(struct drbd_state_change *state_change)
 #undef REMEMBER_STATE_CHANGE
 }
 
+/* takes old and new peer disk state */
+static bool lost_contact_to_peer_data(enum drbd_disk_state os, enum drbd_disk_state ns)
+{
+	if ((os >= D_INCONSISTENT && os != D_UNKNOWN && os != D_OUTDATED)
+	&&  (ns < D_INCONSISTENT || ns == D_UNKNOWN || ns == D_OUTDATED))
+		return true;
+
+	/* Scenario, starting with normal operation
+	 * Connected Primary/Secondary UpToDate/UpToDate
+	 * NetworkFailure Primary/Unknown UpToDate/DUnknown (frozen)
+	 * ...
+	 * Connected Primary/Secondary UpToDate/Diskless (resumed; needs to bump uuid!)
+	 */
+	if (os == D_UNKNOWN
+	&&  (ns == D_DISKLESS || ns == D_FAILED || ns == D_OUTDATED))
+		return true;
+
+	return false;
+}
+
 /**
  * after_state_ch() - Perform after state change actions that may sleep
  * @device:	DRBD device.
@@ -1675,7 +1705,7 @@ static void after_state_ch(struct drbd_device *device, union drbd_state os,
 			what = RESEND;
 
 		if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
-		    conn_lowest_disk(connection) > D_NEGOTIATING)
+		    conn_lowest_disk(connection) == D_UP_TO_DATE)
 			what = RESTART_FROZEN_DISK_IO;
 
 		if (resource->susp_nod && what != NOTHING) {
@@ -1699,6 +1729,13 @@ static void after_state_ch(struct drbd_device *device, union drbd_state os,
 			idr_for_each_entry(&connection->peer_devices, peer_device, vnr)
 				clear_bit(NEW_CUR_UUID, &peer_device->device->flags);
 			rcu_read_unlock();
+
+			/* We should actively create a new uuid, _before_
+			 * we resume/resent, if the peer is diskless
+			 * (recovery from a multiple error scenario).
+			 * Currently, this happens with a slight delay
+			 * below when checking lost_contact_to_peer_data() ...
+			 */
 			_tl_restart(connection, RESEND);
 			_conn_request_state(connection,
 					    (union drbd_state) { { .susp_fen = 1 } },
@@ -1742,12 +1779,7 @@ static void after_state_ch(struct drbd_device *device, union drbd_state os,
 				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 (lost_contact_to_peer_data(os.pdsk, ns.pdsk)) {
 		if (get_ldev(device)) {
 			if ((ns.role == R_PRIMARY || ns.peer == R_PRIMARY) &&
 			    device->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
@@ -1934,12 +1966,17 @@ static void after_state_ch(struct drbd_device *device, union drbd_state os,
 
 	/* 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.
+	 * failure, or on transition from resync back to AHEAD/BEHIND.
+	 *
+	 * Connection loss is handled in drbd_disconnected() by the receiver.
+	 *
 	 * 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(device)) {
+	if ((os.conn > C_CONNECTED && os.conn < C_AHEAD) &&
+	    (ns.conn == C_CONNECTED || ns.conn >= C_AHEAD) && get_ldev(device)) {
 		drbd_queue_bitmap_io(device, &drbd_bm_write_copy_pages, NULL,
 			"write from resync_finished", BM_LOCKED_CHANGE_ALLOWED);
 		put_ldev(device);
@@ -2160,9 +2197,7 @@ conn_set_state(struct drbd_connection *connection, union drbd_state mask, union
 			ns.disk = os.disk;
 
 		rv = _drbd_set_state(device, ns, flags, NULL);
-		if (rv < SS_SUCCESS)
-			BUG();
-
+		BUG_ON(rv < SS_SUCCESS);
 		ns.i = device->state.i;
 		ns_max.role = max_role(ns.role, ns_max.role);
 		ns_max.peer = max_role(ns.peer, ns_max.peer);
diff --git a/drivers/block/drbd/drbd_state.h b/drivers/block/drbd/drbd_state.h
index bd989536f888..6c9d5d4a8a75 100644
--- a/drivers/block/drbd/drbd_state.h
+++ b/drivers/block/drbd/drbd_state.h
@@ -140,7 +140,7 @@ extern void drbd_resume_al(struct drbd_device *device);
 extern bool conn_all_vols_unconf(struct drbd_connection *connection);
 
 /**
- * drbd_request_state() - Reqest a state change
+ * drbd_request_state() - Request a state change
  * @device:	DRBD device.
  * @mask:	mask of state bits to change.
  * @val:	value of new state bits.
diff --git a/drivers/block/drbd/drbd_strings.c b/drivers/block/drbd/drbd_strings.c
index 80b0f63c7075..0eeab14776e9 100644
--- a/drivers/block/drbd/drbd_strings.c
+++ b/drivers/block/drbd/drbd_strings.c
@@ -26,7 +26,7 @@
 #include <linux/drbd.h>
 #include "drbd_strings.h"
 
-static const char *drbd_conn_s_names[] = {
+static const char * const drbd_conn_s_names[] = {
 	[C_STANDALONE]       = "StandAlone",
 	[C_DISCONNECTING]    = "Disconnecting",
 	[C_UNCONNECTED]      = "Unconnected",
@@ -53,13 +53,13 @@ static const char *drbd_conn_s_names[] = {
 	[C_BEHIND]           = "Behind",
 };
 
-static const char *drbd_role_s_names[] = {
+static const char * const drbd_role_s_names[] = {
 	[R_PRIMARY]   = "Primary",
 	[R_SECONDARY] = "Secondary",
 	[R_UNKNOWN]   = "Unknown"
 };
 
-static const char *drbd_disk_s_names[] = {
+static const char * const drbd_disk_s_names[] = {
 	[D_DISKLESS]     = "Diskless",
 	[D_ATTACHING]    = "Attaching",
 	[D_FAILED]       = "Failed",
@@ -71,7 +71,7 @@ static const char *drbd_disk_s_names[] = {
 	[D_UP_TO_DATE]   = "UpToDate",
 };
 
-static const char *drbd_state_sw_errors[] = {
+static const char * const drbd_state_sw_errors[] = {
 	[-SS_TWO_PRIMARIES] = "Multiple primaries not allowed by config",
 	[-SS_NO_UP_TO_DATE_DISK] = "Need access to UpToDate data",
 	[-SS_NO_LOCAL_DISK] = "Can not resync without local disk",
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 51fab978eb61..35dbb3dca47e 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -173,8 +173,8 @@ void drbd_peer_request_endio(struct bio *bio)
 {
 	struct drbd_peer_request *peer_req = bio->bi_private;
 	struct drbd_device *device = peer_req->peer_device->device;
-	int is_write = bio_data_dir(bio) == WRITE;
-	int is_discard = !!(bio_op(bio) == REQ_OP_DISCARD);
+	bool is_write = bio_data_dir(bio) == WRITE;
+	bool is_discard = !!(bio_op(bio) == REQ_OP_DISCARD);
 
 	if (bio->bi_error && __ratelimit(&drbd_ratelimit_state))
 		drbd_warn(device, "%s: error=%d s=%llus\n",
@@ -248,18 +248,26 @@ void drbd_request_endio(struct bio *bio)
 
 	/* to avoid recursion in __req_mod */
 	if (unlikely(bio->bi_error)) {
-		if (bio_op(bio) == REQ_OP_DISCARD)
-			what = (bio->bi_error == -EOPNOTSUPP)
-				? DISCARD_COMPLETED_NOTSUPP
-				: DISCARD_COMPLETED_WITH_ERROR;
-		else
-			what = (bio_data_dir(bio) == WRITE)
-			? WRITE_COMPLETED_WITH_ERROR
-			: (bio_rw(bio) == READ)
-			  ? READ_COMPLETED_WITH_ERROR
-			  : READ_AHEAD_COMPLETED_WITH_ERROR;
-	} else
+		switch (bio_op(bio)) {
+		case REQ_OP_DISCARD:
+			if (bio->bi_error == -EOPNOTSUPP)
+				what = DISCARD_COMPLETED_NOTSUPP;
+			else
+				what = DISCARD_COMPLETED_WITH_ERROR;
+			break;
+		case REQ_OP_READ:
+			if (bio->bi_rw & REQ_RAHEAD)
+				what = READ_AHEAD_COMPLETED_WITH_ERROR;
+			else
+				what = READ_COMPLETED_WITH_ERROR;
+			break;
+		default:
+			what = WRITE_COMPLETED_WITH_ERROR;
+			break;
+		}
+	} else {
 		what = COMPLETED_OK;
+	}
 
 	bio_put(req->private_bio);
 	req->private_bio = ERR_PTR(bio->bi_error);
@@ -320,6 +328,10 @@ void drbd_csum_bio(struct crypto_ahash *tfm, struct bio *bio, void *digest)
 		sg_set_page(&sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset);
 		ahash_request_set_crypt(req, &sg, NULL, sg.length);
 		crypto_ahash_update(req);
+		/* REQ_OP_WRITE_SAME has only one segment,
+		 * checksum the payload only once. */
+		if (bio_op(bio) == REQ_OP_WRITE_SAME)
+			break;
 	}
 	ahash_request_set_crypt(req, NULL, digest, 0);
 	crypto_ahash_final(req);
@@ -387,7 +399,7 @@ static int read_for_csum(struct drbd_peer_device *peer_device, sector_t sector,
 	/* GFP_TRY, because if there is no memory available right now, this may
 	 * be rescheduled for later. It is "only" background resync, after all. */
 	peer_req = drbd_alloc_peer_req(peer_device, ID_SYNCER /* unused */, sector,
-				       size, true /* has real payload */, GFP_TRY);
+				       size, size, GFP_TRY);
 	if (!peer_req)
 		goto defer;
 
@@ -583,6 +595,7 @@ static int make_resync_request(struct drbd_device *const device, int cancel)
 	int number, rollback_i, size;
 	int align, requeue = 0;
 	int i = 0;
+	int discard_granularity = 0;
 
 	if (unlikely(cancel))
 		return 0;
@@ -602,6 +615,12 @@ static int make_resync_request(struct drbd_device *const device, int cancel)
 		return 0;
 	}
 
+	if (connection->agreed_features & DRBD_FF_THIN_RESYNC) {
+		rcu_read_lock();
+		discard_granularity = rcu_dereference(device->ldev->disk_conf)->rs_discard_granularity;
+		rcu_read_unlock();
+	}
+
 	max_bio_size = queue_max_hw_sectors(device->rq_queue) << 9;
 	number = drbd_rs_number_requests(device);
 	if (number <= 0)
@@ -666,6 +685,9 @@ next_sector:
 			if (sector & ((1<<(align+3))-1))
 				break;
 
+			if (discard_granularity && size == discard_granularity)
+				break;
+
 			/* do not cross extent boundaries */
 			if (((bit+1) & BM_BLOCKS_PER_BM_EXT_MASK) == 0)
 				break;
@@ -712,7 +734,8 @@ next_sector:
 			int err;
 
 			inc_rs_pending(device);
-			err = drbd_send_drequest(peer_device, P_RS_DATA_REQUEST,
+			err = drbd_send_drequest(peer_device,
+						 size == discard_granularity ? P_RS_THIN_REQ : P_RS_DATA_REQUEST,
 						 sector, size, ID_SYNCER);
 			if (err) {
 				drbd_err(device, "drbd_send_drequest() failed, aborting...\n");
@@ -829,6 +852,7 @@ static void ping_peer(struct drbd_device *device)
 
 int drbd_resync_finished(struct drbd_device *device)
 {
+	struct drbd_connection *connection = first_peer_device(device)->connection;
 	unsigned long db, dt, dbdt;
 	unsigned long n_oos;
 	union drbd_state os, ns;
@@ -850,8 +874,7 @@ int drbd_resync_finished(struct drbd_device *device)
 		if (dw) {
 			dw->w.cb = w_resync_finished;
 			dw->device = device;
-			drbd_queue_work(&first_peer_device(device)->connection->sender_work,
-					&dw->w);
+			drbd_queue_work(&connection->sender_work, &dw->w);
 			return 1;
 		}
 		drbd_err(device, "Warn failed to drbd_rs_del_all() and to kmalloc(dw).\n");
@@ -964,6 +987,30 @@ int drbd_resync_finished(struct drbd_device *device)
 	_drbd_set_state(device, ns, CS_VERBOSE, NULL);
 out_unlock:
 	spin_unlock_irq(&device->resource->req_lock);
+
+	/* If we have been sync source, and have an effective fencing-policy,
+	 * once *all* volumes are back in sync, call "unfence". */
+	if (os.conn == C_SYNC_SOURCE) {
+		enum drbd_disk_state disk_state = D_MASK;
+		enum drbd_disk_state pdsk_state = D_MASK;
+		enum drbd_fencing_p fp = FP_DONT_CARE;
+
+		rcu_read_lock();
+		fp = rcu_dereference(device->ldev->disk_conf)->fencing;
+		if (fp != FP_DONT_CARE) {
+			struct drbd_peer_device *peer_device;
+			int vnr;
+			idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+				struct drbd_device *device = peer_device->device;
+				disk_state = min_t(enum drbd_disk_state, disk_state, device->state.disk);
+				pdsk_state = min_t(enum drbd_disk_state, pdsk_state, device->state.pdsk);
+			}
+		}
+		rcu_read_unlock();
+		if (disk_state == D_UP_TO_DATE && pdsk_state == D_UP_TO_DATE)
+			conn_khelper(connection, "unfence-peer");
+	}
+
 	put_ldev(device);
 out:
 	device->rs_total  = 0;
@@ -1000,7 +1047,6 @@ static void move_to_net_ee_or_free(struct drbd_device *device, struct drbd_peer_
 
 /**
  * w_e_end_data_req() - Worker callback, to send a P_DATA_REPLY packet in response to a P_DATA_REQUEST
- * @device:	DRBD device.
  * @w:		work object.
  * @cancel:	The connection will be closed anyways
  */
@@ -1036,6 +1082,30 @@ int w_e_end_data_req(struct drbd_work *w, int cancel)
 	return err;
 }
 
+static bool all_zero(struct drbd_peer_request *peer_req)
+{
+	struct page *page = peer_req->pages;
+	unsigned int len = peer_req->i.size;
+
+	page_chain_for_each(page) {
+		unsigned int l = min_t(unsigned int, len, PAGE_SIZE);
+		unsigned int i, words = l / sizeof(long);
+		unsigned long *d;
+
+		d = kmap_atomic(page);
+		for (i = 0; i < words; i++) {
+			if (d[i]) {
+				kunmap_atomic(d);
+				return false;
+			}
+		}
+		kunmap_atomic(d);
+		len -= l;
+	}
+
+	return true;
+}
+
 /**
  * w_e_end_rsdata_req() - Worker callback to send a P_RS_DATA_REPLY packet in response to a P_RS_DATA_REQUEST
  * @w:		work object.
@@ -1064,7 +1134,10 @@ int w_e_end_rsdata_req(struct drbd_work *w, int cancel)
 	} else if (likely((peer_req->flags & EE_WAS_ERROR) == 0)) {
 		if (likely(device->state.pdsk >= D_INCONSISTENT)) {
 			inc_rs_pending(device);
-			err = drbd_send_block(peer_device, P_RS_DATA_REPLY, peer_req);
+			if (peer_req->flags & EE_RS_THIN_REQ && all_zero(peer_req))
+				err = drbd_send_rs_deallocated(peer_device, peer_req);
+			else
+				err = drbd_send_block(peer_device, P_RS_DATA_REPLY, peer_req);
 		} else {
 			if (__ratelimit(&drbd_ratelimit_state))
 				drbd_err(device, "Not sending RSDataReply, "
@@ -1634,7 +1707,7 @@ static bool use_checksum_based_resync(struct drbd_connection *connection, struct
 	rcu_read_unlock();
 	return connection->agreed_pro_version >= 89 &&		/* supported? */
 		connection->csums_tfm &&			/* configured? */
-		(csums_after_crash_only == 0			/* use for each resync? */
+		(csums_after_crash_only == false		/* use for each resync? */
 		 || test_bit(CRASHED_PRIMARY, &device->flags));	/* or only after Primary crash? */
 }
 
@@ -1769,7 +1842,7 @@ void drbd_start_resync(struct drbd_device *device, enum drbd_conns side)
 			device->bm_resync_fo = 0;
 			device->use_csums = use_checksum_based_resync(connection, device);
 		} else {
-			device->use_csums = 0;
+			device->use_csums = false;
 		}
 
 		/* Since protocol 96, we must serialize drbd_gen_and_send_sync_uuid
author	Linus Torvalds <torvalds@linux-foundation.org>	2016-07-26 15:37:51 -0700
committer	Linus Torvalds <torvalds@linux-foundation.org>	2016-07-26 15:37:51 -0700
commit	3fc9d690936fb2e20e180710965ba2cc3a0881f8 (patch)
tree	eaf4d9f788ee4d17cd40a116413873b7f80f9aa7 /drivers/block/drbd
parent	d05d7f40791ccbb6e543cc5dd6a6aa08fc71d635 (diff)
parent	13880f5b57adf34d050cf7e229a6326da45a7347 (diff)