Merge branch 'for-2.6.37/drivers' into for-linus

Conflicts:
	drivers/block/cciss.c

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

10 files changed, 264 insertions, 412 deletions

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 2cdbc247d0ac..a67d0a611a8a 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -113,6 +113,8 @@ static struct board_type products[] = {
 	{0x409D0E11, "Smart Array 6400 EM", &SA5_access},
 	{0x40910E11, "Smart Array 6i", &SA5_access},
 	{0x3225103C, "Smart Array P600", &SA5_access},
+	{0x3223103C, "Smart Array P800", &SA5_access},
+	{0x3234103C, "Smart Array P400", &SA5_access},
 	{0x3235103C, "Smart Array P400i", &SA5_access},
 	{0x3211103C, "Smart Array E200i", &SA5_access},
 	{0x3212103C, "Smart Array E200", &SA5_access},
@@ -3753,7 +3755,7 @@ static void __devinit cciss_wait_for_mode_change_ack(ctlr_info_t *h)
 	for (i = 0; i < MAX_CONFIG_WAIT; i++) {
 		if (!(readl(h->vaddr + SA5_DOORBELL) & CFGTBL_ChangeReq))
 			break;
-		msleep(10);
+		usleep_range(10000, 20000);
 	}
 }
 
@@ -3937,10 +3939,9 @@ static int __devinit cciss_lookup_board_id(struct pci_dev *pdev, u32 *board_id)
 	*board_id = ((subsystem_device_id << 16) & 0xffff0000) |
 			subsystem_vendor_id;
 
-	for (i = 0; i < ARRAY_SIZE(products); i++) {
+	for (i = 0; i < ARRAY_SIZE(products); i++)
 		if (*board_id == products[i].board_id)
 			return i;
-	}
 	dev_warn(&pdev->dev, "unrecognized board ID: 0x%08x, ignoring.\n",
 		*board_id);
 	return -ENODEV;
@@ -3971,18 +3972,31 @@ static int __devinit cciss_pci_find_memory_BAR(struct pci_dev *pdev,
 	return -ENODEV;
 }
 
-static int __devinit cciss_wait_for_board_ready(ctlr_info_t *h)
+static int __devinit cciss_wait_for_board_state(struct pci_dev *pdev,
+	void __iomem *vaddr, int wait_for_ready)
+#define BOARD_READY 1
+#define BOARD_NOT_READY 0
 {
-	int i;
+	int i, iterations;
 	u32 scratchpad;
 
-	for (i = 0; i < CCISS_BOARD_READY_ITERATIONS; i++) {
-		scratchpad = readl(h->vaddr + SA5_SCRATCHPAD_OFFSET);
-		if (scratchpad == CCISS_FIRMWARE_READY)
-			return 0;
+	if (wait_for_ready)
+		iterations = CCISS_BOARD_READY_ITERATIONS;
+	else
+		iterations = CCISS_BOARD_NOT_READY_ITERATIONS;
+
+	for (i = 0; i < iterations; i++) {
+		scratchpad = readl(vaddr + SA5_SCRATCHPAD_OFFSET);
+		if (wait_for_ready) {
+			if (scratchpad == CCISS_FIRMWARE_READY)
+				return 0;
+		} else {
+			if (scratchpad != CCISS_FIRMWARE_READY)
+				return 0;
+		}
 		msleep(CCISS_BOARD_READY_POLL_INTERVAL_MSECS);
 	}
-	dev_warn(&h->pdev->dev, "board not ready, timed out.\n");
+	dev_warn(&pdev->dev, "board not ready, timed out.\n");
 	return -ENODEV;
 }
 
@@ -4031,6 +4045,11 @@ static int __devinit cciss_find_cfgtables(ctlr_info_t *h)
 static void __devinit cciss_get_max_perf_mode_cmds(struct ctlr_info *h)
 {
 	h->max_commands = readl(&(h->cfgtable->MaxPerformantModeCommands));
+
+	/* Limit commands in memory limited kdump scenario. */
+	if (reset_devices && h->max_commands > 32)
+		h->max_commands = 32;
+
 	if (h->max_commands < 16) {
 		dev_warn(&h->pdev->dev, "Controller reports "
 			"max supported commands of %d, an obvious lie. "
@@ -4148,7 +4167,7 @@ static int __devinit cciss_pci_init(ctlr_info_t *h)
 		err = -ENOMEM;
 		goto err_out_free_res;
 	}
-	err = cciss_wait_for_board_ready(h);
+	err = cciss_wait_for_board_state(h->pdev, h->vaddr, BOARD_READY);
 	if (err)
 		goto err_out_free_res;
 	err = cciss_find_cfgtables(h);
@@ -4313,36 +4332,6 @@ static __devinit int cciss_message(struct pci_dev *pdev, unsigned char opcode, u
 #define cciss_soft_reset_controller(p) cciss_message(p, 1, 0)
 #define cciss_noop(p) cciss_message(p, 3, 0)
 
-static __devinit int cciss_reset_msi(struct pci_dev *pdev)
-{
-/* the #defines are stolen from drivers/pci/msi.h. */
-#define msi_control_reg(base)		(base + PCI_MSI_FLAGS)
-#define PCI_MSIX_FLAGS_ENABLE		(1 << 15)
-
-	int pos;
-	u16 control = 0;
-
-	pos = pci_find_capability(pdev, PCI_CAP_ID_MSI);
-	if (pos) {
-		pci_read_config_word(pdev, msi_control_reg(pos), &control);
-		if (control & PCI_MSI_FLAGS_ENABLE) {
-			dev_info(&pdev->dev, "resetting MSI\n");
-			pci_write_config_word(pdev, msi_control_reg(pos), control & ~PCI_MSI_FLAGS_ENABLE);
-		}
-	}
-
-	pos = pci_find_capability(pdev, PCI_CAP_ID_MSIX);
-	if (pos) {
-		pci_read_config_word(pdev, msi_control_reg(pos), &control);
-		if (control & PCI_MSIX_FLAGS_ENABLE) {
-			dev_info(&pdev->dev, "resetting MSI-X\n");
-			pci_write_config_word(pdev, msi_control_reg(pos), control & ~PCI_MSIX_FLAGS_ENABLE);
-		}
-	}
-
-	return 0;
-}
-
 static int cciss_controller_hard_reset(struct pci_dev *pdev,
 	void * __iomem vaddr, bool use_doorbell)
 {
@@ -4397,17 +4386,17 @@ static int cciss_controller_hard_reset(struct pci_dev *pdev,
  * states or using the doorbell register. */
 static __devinit int cciss_kdump_hard_reset_controller(struct pci_dev *pdev)
 {
-	u16 saved_config_space[32];
 	u64 cfg_offset;
 	u32 cfg_base_addr;
 	u64 cfg_base_addr_index;
 	void __iomem *vaddr;
 	unsigned long paddr;
 	u32 misc_fw_support, active_transport;
-	int rc, i;
+	int rc;
 	CfgTable_struct __iomem *cfgtable;
 	bool use_doorbell;
 	u32 board_id;
+	u16 command_register;
 
 	/* For controllers as old a the p600, this is very nearly
 	 * the same thing as
@@ -4417,14 +4406,6 @@ static __devinit int cciss_kdump_hard_reset_controller(struct pci_dev *pdev)
 	 * pci_set_power_state(pci_dev, PCI_D0);
 	 * pci_restore_state(pci_dev);
 	 *
-	 * but we can't use these nice canned kernel routines on
-	 * kexec, because they also check the MSI/MSI-X state in PCI
-	 * configuration space and do the wrong thing when it is
-	 * set/cleared.  Also, the pci_save/restore_state functions
-	 * violate the ordering requirements for restoring the
-	 * configuration space from the CCISS document (see the
-	 * comment below).  So we roll our own ....
-	 *
 	 * For controllers newer than the P600, the pci power state
 	 * method of resetting doesn't work so we have another way
 	 * using the doorbell register.
@@ -4443,8 +4424,13 @@ static __devinit int cciss_kdump_hard_reset_controller(struct pci_dev *pdev)
 		return -ENODEV;
 	}
 
-	for (i = 0; i < 32; i++)
-		pci_read_config_word(pdev, 2*i, &saved_config_space[i]);
+	/* Save the PCI command register */
+	pci_read_config_word(pdev, 4, &command_register);
+	/* Turn the board off.  This is so that later pci_restore_state()
+	 * won't turn the board on before the rest of config space is ready.
+	 */
+	pci_disable_device(pdev);
+	pci_save_state(pdev);
 
 	/* find the first memory BAR, so we can find the cfg table */
 	rc = cciss_pci_find_memory_BAR(pdev, &paddr);
@@ -4479,26 +4465,32 @@ static __devinit int cciss_kdump_hard_reset_controller(struct pci_dev *pdev)
 	rc = cciss_controller_hard_reset(pdev, vaddr, use_doorbell);
 	if (rc)
 		goto unmap_cfgtable;
-
-	/* Restore the PCI configuration space.  The Open CISS
-	 * Specification says, "Restore the PCI Configuration
-	 * Registers, offsets 00h through 60h. It is important to
-	 * restore the command register, 16-bits at offset 04h,
-	 * last. Do not restore the configuration status register,
-	 * 16-bits at offset 06h."  Note that the offset is 2*i.
-	 */
-	for (i = 0; i < 32; i++) {
-		if (i == 2 || i == 3)
-			continue;
-		pci_write_config_word(pdev, 2*i, saved_config_space[i]);
+	pci_restore_state(pdev);
+	rc = pci_enable_device(pdev);
+	if (rc) {
+		dev_warn(&pdev->dev, "failed to enable device.\n");
+		goto unmap_cfgtable;
 	}
-	wmb();
-	pci_write_config_word(pdev, 4, saved_config_space[2]);
+	pci_write_config_word(pdev, 4, command_register);
 
 	/* Some devices (notably the HP Smart Array 5i Controller)
 	   need a little pause here */
 	msleep(CCISS_POST_RESET_PAUSE_MSECS);
 
+	/* Wait for board to become not ready, then ready. */
+	dev_info(&pdev->dev, "Waiting for board to become ready.\n");
+	rc = cciss_wait_for_board_state(pdev, vaddr, BOARD_NOT_READY);
+	if (rc) /* Don't bail, might be E500, etc. which can't be reset */
+		dev_warn(&pdev->dev,
+			"failed waiting for board to become not ready\n");
+	rc = cciss_wait_for_board_state(pdev, vaddr, BOARD_READY);
+	if (rc) {
+		dev_warn(&pdev->dev,
+			"failed waiting for board to become ready\n");
+		goto unmap_cfgtable;
+	}
+	dev_info(&pdev->dev, "board ready.\n");
+
 	/* Controller should be in simple mode at this point.  If it's not,
 	 * It means we're on one of those controllers which doesn't support
 	 * the doorbell reset method and on which the PCI power management reset
@@ -4539,8 +4531,6 @@ static __devinit int cciss_init_reset_devices(struct pci_dev *pdev)
 		return 0; /* just try to do the kdump anyhow. */
 	if (rc)
 		return -ENODEV;
-	if (cciss_reset_msi(pdev))
-		return -ENODEV;
 
 	/* Now try to get the controller to respond to a no-op */
 	for (i = 0; i < CCISS_POST_RESET_NOOP_RETRIES; i++) {
diff --git a/drivers/block/cciss.h b/drivers/block/cciss.h
index ae340ffc8f81..4b8933d778f1 100644
--- a/drivers/block/cciss.h
+++ b/drivers/block/cciss.h
@@ -200,10 +200,14 @@ struct ctlr_info
  * the above.
  */
 #define CCISS_BOARD_READY_WAIT_SECS (120)
+#define CCISS_BOARD_NOT_READY_WAIT_SECS (10)
 #define CCISS_BOARD_READY_POLL_INTERVAL_MSECS (100)
 #define CCISS_BOARD_READY_ITERATIONS \
 	((CCISS_BOARD_READY_WAIT_SECS * 1000) / \
 		CCISS_BOARD_READY_POLL_INTERVAL_MSECS)
+#define CCISS_BOARD_NOT_READY_ITERATIONS \
+	((CCISS_BOARD_NOT_READY_WAIT_SECS * 1000) / \
+		CCISS_BOARD_READY_POLL_INTERVAL_MSECS)
 #define CCISS_POST_RESET_PAUSE_MSECS (3000)
 #define CCISS_POST_RESET_NOOP_INTERVAL_MSECS (1000)
 #define CCISS_POST_RESET_NOOP_RETRIES (12)
diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index ac04ef97eac2..ba95cba192be 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -78,11 +78,10 @@ static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
 	init_completion(&md_io.event);
 	md_io.error = 0;
 
-	if ((rw & WRITE) && !test_bit(MD_NO_BARRIER, &mdev->flags))
-		rw |= REQ_HARDBARRIER;
+	if ((rw & WRITE) && !test_bit(MD_NO_FUA, &mdev->flags))
+		rw |= REQ_FUA;
 	rw |= REQ_UNPLUG | REQ_SYNC;
 
- retry:
 	bio = bio_alloc(GFP_NOIO, 1);
 	bio->bi_bdev = bdev->md_bdev;
 	bio->bi_sector = sector;
@@ -100,17 +99,6 @@ static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
 	wait_for_completion(&md_io.event);
 	ok = bio_flagged(bio, BIO_UPTODATE) && md_io.error == 0;
 
-	/* check for unsupported barrier op.
-	 * would rather check on EOPNOTSUPP, but that is not reliable.
-	 * don't try again for ANY return value != 0 */
-	if (unlikely((bio->bi_rw & REQ_HARDBARRIER) && !ok)) {
-		/* Try again with no barrier */
-		dev_warn(DEV, "Barriers not supported on meta data device - disabling\n");
-		set_bit(MD_NO_BARRIER, &mdev->flags);
-		rw &= ~REQ_HARDBARRIER;
-		bio_put(bio);
-		goto retry;
-	}
  out:
 	bio_put(bio);
 	return ok;
@@ -284,18 +272,32 @@ w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
 	u32 xor_sum = 0;
 
 	if (!get_ldev(mdev)) {
-		dev_err(DEV, "get_ldev() failed in w_al_write_transaction\n");
+		dev_err(DEV,
+			"disk is %s, cannot start al transaction (-%d +%d)\n",
+			drbd_disk_str(mdev->state.disk), evicted, new_enr);
 		complete(&((struct update_al_work *)w)->event);
 		return 1;
 	}
 	/* do we have to do a bitmap write, first?
 	 * TODO reduce maximum latency:
 	 * submit both bios, then wait for both,
-	 * instead of doing two synchronous sector writes. */
+	 * instead of doing two synchronous sector writes.
+	 * For now, we must not write the transaction,
+	 * if we cannot write out the bitmap of the evicted extent. */
 	if (mdev->state.conn < C_CONNECTED && evicted != LC_FREE)
 		drbd_bm_write_sect(mdev, evicted/AL_EXT_PER_BM_SECT);
 
-	mutex_lock(&mdev->md_io_mutex); /* protects md_io_page, al_tr_cycle, ... */
+	/* The bitmap write may have failed, causing a state change. */
+	if (mdev->state.disk < D_INCONSISTENT) {
+		dev_err(DEV,
+			"disk is %s, cannot write al transaction (-%d +%d)\n",
+			drbd_disk_str(mdev->state.disk), evicted, new_enr);
+		complete(&((struct update_al_work *)w)->event);
+		put_ldev(mdev);
+		return 1;
+	}
+
+	mutex_lock(&mdev->md_io_mutex); /* protects md_io_buffer, al_tr_cycle, ... */
 	buffer = (struct al_transaction *)page_address(mdev->md_io_page);
 
 	buffer->magic = __constant_cpu_to_be32(DRBD_MAGIC);
@@ -739,7 +741,7 @@ void drbd_al_apply_to_bm(struct drbd_conf *mdev)
 	unsigned int enr;
 	unsigned long add = 0;
 	char ppb[10];
-	int i;
+	int i, tmp;
 
 	wait_event(mdev->al_wait, lc_try_lock(mdev->act_log));
 
@@ -747,7 +749,9 @@ void drbd_al_apply_to_bm(struct drbd_conf *mdev)
 		enr = lc_element_by_index(mdev->act_log, i)->lc_number;
 		if (enr == LC_FREE)
 			continue;
-		add += drbd_bm_ALe_set_all(mdev, enr);
+		tmp = drbd_bm_ALe_set_all(mdev, enr);
+		dynamic_dev_dbg(DEV, "AL: set %d bits in extent %u\n", tmp, enr);
+		add += tmp;
 	}
 
 	lc_unlock(mdev->act_log);
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 2637f499f77f..1ea1a34e78b2 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -114,11 +114,11 @@ struct drbd_conf;
 #define D_ASSERT(exp)	if (!(exp)) \
 	 dev_err(DEV, "ASSERT( " #exp " ) in %s:%d\n", __FILE__, __LINE__)
 
-#define ERR_IF(exp) if (({				\
-	int _b = (exp) != 0;				\
-	if (_b) dev_err(DEV, "%s: (%s) in %s:%d\n",	\
-		__func__, #exp, __FILE__, __LINE__);	\
-	 _b;						\
+#define ERR_IF(exp) if (({						\
+	int _b = (exp) != 0;						\
+	if (_b) dev_err(DEV, "ASSERT FAILED: %s: (%s) in %s:%d\n",	\
+			__func__, #exp, __FILE__, __LINE__);		\
+	_b;								\
 	}))
 
 /* Defines to control fault insertion */
@@ -749,17 +749,12 @@ struct drbd_epoch {
 
 /* drbd_epoch flag bits */
 enum {
-	DE_BARRIER_IN_NEXT_EPOCH_ISSUED,
-	DE_BARRIER_IN_NEXT_EPOCH_DONE,
-	DE_CONTAINS_A_BARRIER,
 	DE_HAVE_BARRIER_NUMBER,
-	DE_IS_FINISHING,
 };
 
 enum epoch_event {
 	EV_PUT,
 	EV_GOT_BARRIER_NR,
-	EV_BARRIER_DONE,
 	EV_BECAME_LAST,
 	EV_CLEANUP = 32, /* used as flag */
 };
@@ -801,11 +796,6 @@ enum {
 	__EE_CALL_AL_COMPLETE_IO,
 	__EE_MAY_SET_IN_SYNC,
 
-	/* This epoch entry closes an epoch using a barrier.
-	 * On sucessful completion, the epoch is released,
-	 * and the P_BARRIER_ACK send. */
-	__EE_IS_BARRIER,
-
 	/* In case a barrier failed,
 	 * we need to resubmit without the barrier flag. */
 	__EE_RESUBMITTED,
@@ -820,7 +810,6 @@ enum {
 };
 #define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
 #define EE_MAY_SET_IN_SYNC     (1<<__EE_MAY_SET_IN_SYNC)
-#define EE_IS_BARRIER          (1<<__EE_IS_BARRIER)
 #define	EE_RESUBMITTED         (1<<__EE_RESUBMITTED)
 #define EE_WAS_ERROR           (1<<__EE_WAS_ERROR)
 #define EE_HAS_DIGEST          (1<<__EE_HAS_DIGEST)
@@ -843,16 +832,15 @@ enum {
 				 * Gets cleared when the state.conn
 				 * goes into C_CONNECTED state. */
 	WRITE_BM_AFTER_RESYNC,	/* A kmalloc() during resync failed */
-	NO_BARRIER_SUPP,	/* underlying block device doesn't implement barriers */
 	CONSIDER_RESYNC,
 
-	MD_NO_BARRIER,		/* meta data device does not support barriers,
-				   so don't even try */
+	MD_NO_FUA,		/* Users wants us to not use FUA/FLUSH on meta data dev */
 	SUSPEND_IO,		/* suspend application io */
 	BITMAP_IO,		/* suspend application io;
 				   once no more io in flight, start bitmap io */
 	BITMAP_IO_QUEUED,       /* Started bitmap IO */
-	GO_DISKLESS,		/* Disk failed, local_cnt reached zero, we are going diskless */
+	GO_DISKLESS,		/* Disk is being detached, on io-error or admin request. */
+	WAS_IO_ERROR,		/* Local disk failed returned IO error */
 	RESYNC_AFTER_NEG,       /* Resync after online grow after the attach&negotiate finished. */
 	NET_CONGESTED,		/* The data socket is congested */
 
@@ -947,7 +935,6 @@ enum write_ordering_e {
 	WO_none,
 	WO_drain_io,
 	WO_bdev_flush,
-	WO_bio_barrier
 };
 
 struct fifo_buffer {
@@ -1281,6 +1268,7 @@ extern int drbd_bmio_set_n_write(struct drbd_conf *mdev);
 extern int drbd_bmio_clear_n_write(struct drbd_conf *mdev);
 extern int drbd_bitmap_io(struct drbd_conf *mdev, int (*io_fn)(struct drbd_conf *), char *why);
 extern void drbd_go_diskless(struct drbd_conf *mdev);
+extern void drbd_ldev_destroy(struct drbd_conf *mdev);
 
 
 /* Meta data layout
@@ -1798,17 +1786,17 @@ static inline void __drbd_chk_io_error_(struct drbd_conf *mdev, int forcedetach,
 	case EP_PASS_ON:
 		if (!forcedetach) {
 			if (__ratelimit(&drbd_ratelimit_state))
-				dev_err(DEV, "Local IO failed in %s."
-					     "Passing error on...\n", where);
+				dev_err(DEV, "Local IO failed in %s.\n", where);
 			break;
 		}
 		/* NOTE fall through to detach case if forcedetach set */
 	case EP_DETACH:
 	case EP_CALL_HELPER:
+		set_bit(WAS_IO_ERROR, &mdev->flags);
 		if (mdev->state.disk > D_FAILED) {
 			_drbd_set_state(_NS(mdev, disk, D_FAILED), CS_HARD, NULL);
-			dev_err(DEV, "Local IO failed in %s."
-				     "Detaching...\n", where);
+			dev_err(DEV,
+				"Local IO failed in %s. Detaching...\n", where);
 		}
 		break;
 	}
@@ -2127,7 +2115,11 @@ static inline void put_ldev(struct drbd_conf *mdev)
 	__release(local);
 	D_ASSERT(i >= 0);
 	if (i == 0) {
+		if (mdev->state.disk == D_DISKLESS)
+			/* even internal references gone, safe to destroy */
+			drbd_ldev_destroy(mdev);
 		if (mdev->state.disk == D_FAILED)
+			/* all application IO references gone. */
 			drbd_go_diskless(mdev);
 		wake_up(&mdev->misc_wait);
 	}
@@ -2138,6 +2130,10 @@ static inline int _get_ldev_if_state(struct drbd_conf *mdev, enum drbd_disk_stat
 {
 	int io_allowed;
 
+	/* never get a reference while D_DISKLESS */
+	if (mdev->state.disk == D_DISKLESS)
+		return 0;
+
 	atomic_inc(&mdev->local_cnt);
 	io_allowed = (mdev->state.disk >= mins);
 	if (!io_allowed)
@@ -2406,12 +2402,12 @@ static inline void drbd_md_flush(struct drbd_conf *mdev)
 {
 	int r;
 
-	if (test_bit(MD_NO_BARRIER, &mdev->flags))
+	if (test_bit(MD_NO_FUA, &mdev->flags))
 		return;
 
 	r = blkdev_issue_flush(mdev->ldev->md_bdev, GFP_KERNEL, NULL);
 	if (r) {
-		set_bit(MD_NO_BARRIER, &mdev->flags);
+		set_bit(MD_NO_FUA, &mdev->flags);
 		dev_err(DEV, "meta data flush failed with status %d, disabling md-flushes\n", r);
 	}
 }
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 25c7a73c5062..6be5401d0e88 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -835,6 +835,15 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
 	    ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING && ns.conn <= C_TEAR_DOWN)
 		ns.conn = os.conn;
 
+	/* we cannot fail (again) if we already detached */
+	if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
+		ns.disk = D_DISKLESS;
+
+	/* if we are only D_ATTACHING yet,
+	 * we can (and should) go directly to D_DISKLESS. */
+	if (ns.disk == D_FAILED && os.disk == D_ATTACHING)
+		ns.disk = D_DISKLESS;
+
 	/* After C_DISCONNECTING only C_STANDALONE may follow */
 	if (os.conn == C_DISCONNECTING && ns.conn != C_STANDALONE)
 		ns.conn = os.conn;
@@ -1056,7 +1065,15 @@ int __drbd_set_state(struct drbd_conf *mdev,
 	    !test_and_set_bit(CONFIG_PENDING, &mdev->flags))
 		set_bit(DEVICE_DYING, &mdev->flags);
 
-	mdev->state.i = ns.i;
+	/* if we are going -> D_FAILED or D_DISKLESS, grab one extra reference
+	 * on the ldev here, to be sure the transition -> D_DISKLESS resp.
+	 * drbd_ldev_destroy() won't happen before our corresponding
+	 * after_state_ch works run, where we put_ldev again. */
+	if ((os.disk != D_FAILED && ns.disk == D_FAILED) ||
+	    (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))
+		atomic_inc(&mdev->local_cnt);
+
+	mdev->state = ns;
 	wake_up(&mdev->misc_wait);
 	wake_up(&mdev->state_wait);
 
@@ -1268,7 +1285,6 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
 			if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
 				drbd_uuid_new_current(mdev);
 				clear_bit(NEW_CUR_UUID, &mdev->flags);
-				drbd_md_sync(mdev);
 			}
 			spin_lock_irq(&mdev->req_lock);
 			_drbd_set_state(_NS(mdev, susp_fen, 0), CS_VERBOSE, NULL);
@@ -1365,63 +1381,64 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
 	    os.disk > D_INCONSISTENT && ns.disk == D_INCONSISTENT)
 		drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, NULL, "set_n_write from invalidate");
 
-	/* first half of local IO error */
-	if (os.disk > D_FAILED && ns.disk == D_FAILED) {
-		enum drbd_io_error_p eh = EP_PASS_ON;
+	/* first half of local IO error, failure to attach,
+	 * or administrative detach */
+	if (os.disk != D_FAILED && ns.disk == D_FAILED) {
+		enum drbd_io_error_p eh;
+		int was_io_error;
+		/* corresponding get_ldev was in __drbd_set_state, to serialize
+		 * our cleanup here with the transition to D_DISKLESS,
+		 * so it is safe to dreference ldev here. */
+		eh = mdev->ldev->dc.on_io_error;
+		was_io_error = test_and_clear_bit(WAS_IO_ERROR, &mdev->flags);
+
+		/* current state still has to be D_FAILED,
+		 * there is only one way out: to D_DISKLESS,
+		 * and that may only happen after our put_ldev below. */
+		if (mdev->state.disk != D_FAILED)
+			dev_err(DEV,
+				"ASSERT FAILED: disk is %s during detach\n",
+				drbd_disk_str(mdev->state.disk));
 
 		if (drbd_send_state(mdev))
-			dev_warn(DEV, "Notified peer that my disk is broken.\n");
+			dev_warn(DEV, "Notified peer that I am detaching my disk\n");
 		else
-			dev_err(DEV, "Sending state for drbd_io_error() failed\n");
+			dev_err(DEV, "Sending state for detaching disk failed\n");
 
 		drbd_rs_cancel_all(mdev);
 
-		if (get_ldev_if_state(mdev, D_FAILED)) {
-			eh = mdev->ldev->dc.on_io_error;
-			put_ldev(mdev);
-		}
-		if (eh == EP_CALL_HELPER)
+		/* In case we want to get something to stable storage still,
+		 * this may be the last chance.
+		 * Following put_ldev may transition to D_DISKLESS. */
+		drbd_md_sync(mdev);
+		put_ldev(mdev);
+
+		if (was_io_error && eh == EP_CALL_HELPER)
 			drbd_khelper(mdev, "local-io-error");
 	}
 
+        /* second half of local IO error, failure to attach,
+         * or administrative detach,
+         * after local_cnt references have reached zero again */
+        if (os.disk != D_DISKLESS && ns.disk == D_DISKLESS) {
+                /* We must still be diskless,
+                 * re-attach has to be serialized with this! */
+                if (mdev->state.disk != D_DISKLESS)
+                        dev_err(DEV,
+                                "ASSERT FAILED: disk is %s while going diskless\n",
+                                drbd_disk_str(mdev->state.disk));
 
-	/* second half of local IO error handling,
-	 * after local_cnt references have reached zero: */
-	if (os.disk == D_FAILED && ns.disk == D_DISKLESS) {
-		mdev->rs_total = 0;
-		mdev->rs_failed = 0;
-		atomic_set(&mdev->rs_pending_cnt, 0);
-	}
-
-	if (os.disk > D_DISKLESS && ns.disk == D_DISKLESS) {
-		/* We must still be diskless,
-		 * re-attach has to be serialized with this! */
-		if (mdev->state.disk != D_DISKLESS)
-			dev_err(DEV,
-				"ASSERT FAILED: disk is %s while going diskless\n",
-				drbd_disk_str(mdev->state.disk));
+                mdev->rs_total = 0;
+                mdev->rs_failed = 0;
+                atomic_set(&mdev->rs_pending_cnt, 0);
 
-		/* we cannot assert local_cnt == 0 here, as get_ldev_if_state
-		 * will inc/dec it frequently. Since we became D_DISKLESS, no
-		 * one has touched the protected members anymore, though, so we
-		 * are safe to free them here. */
 		if (drbd_send_state(mdev))
-			dev_warn(DEV, "Notified peer that I detached my disk.\n");
+			dev_warn(DEV, "Notified peer that I'm now diskless.\n");
 		else
-			dev_err(DEV, "Sending state for detach failed\n");
-
-		lc_destroy(mdev->resync);
-		mdev->resync = NULL;
-		lc_destroy(mdev->act_log);
-		mdev->act_log = NULL;
-		__no_warn(local,
-			drbd_free_bc(mdev->ldev);
-			mdev->ldev = NULL;);
-
-		if (mdev->md_io_tmpp) {
-			__free_page(mdev->md_io_tmpp);
-			mdev->md_io_tmpp = NULL;
-		}
+			dev_err(DEV, "Sending state for being diskless failed\n");
+		/* corresponding get_ldev in __drbd_set_state
+		 * this may finaly trigger drbd_ldev_destroy. */
+		put_ldev(mdev);
 	}
 
 	/* Disks got bigger while they were detached */
@@ -2772,11 +2789,6 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
 
 	drbd_set_defaults(mdev);
 
-	/* for now, we do NOT yet support it,
-	 * even though we start some framework
-	 * to eventually support barriers */
-	set_bit(NO_BARRIER_SUPP, &mdev->flags);
-
 	atomic_set(&mdev->ap_bio_cnt, 0);
 	atomic_set(&mdev->ap_pending_cnt, 0);
 	atomic_set(&mdev->rs_pending_cnt, 0);
@@ -2842,7 +2854,7 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
 	drbd_thread_init(mdev, &mdev->asender, drbd_asender);
 
 	mdev->agreed_pro_version = PRO_VERSION_MAX;
-	mdev->write_ordering = WO_bio_barrier;
+	mdev->write_ordering = WO_bdev_flush;
 	mdev->resync_wenr = LC_FREE;
 }
 
@@ -2899,7 +2911,6 @@ void drbd_mdev_cleanup(struct drbd_conf *mdev)
 	D_ASSERT(list_empty(&mdev->resync_work.list));
 	D_ASSERT(list_empty(&mdev->unplug_work.list));
 	D_ASSERT(list_empty(&mdev->go_diskless.list));
-
 }
 
 
@@ -3660,6 +3671,8 @@ void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local)
 
 	get_random_bytes(&val, sizeof(u64));
 	_drbd_uuid_set(mdev, UI_CURRENT, val);
+	/* get it to stable storage _now_ */
+	drbd_md_sync(mdev);
 }
 
 void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local)
@@ -3756,19 +3769,31 @@ static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
 	return 1;
 }
 
+void drbd_ldev_destroy(struct drbd_conf *mdev)
+{
+	lc_destroy(mdev->resync);
+	mdev->resync = NULL;
+	lc_destroy(mdev->act_log);
+	mdev->act_log = NULL;
+	__no_warn(local,
+		drbd_free_bc(mdev->ldev);
+		mdev->ldev = NULL;);
+
+	if (mdev->md_io_tmpp) {
+		__free_page(mdev->md_io_tmpp);
+		mdev->md_io_tmpp = NULL;
+	}
+	clear_bit(GO_DISKLESS, &mdev->flags);
+}
+
 static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused)
 {
 	D_ASSERT(mdev->state.disk == D_FAILED);
 	/* we cannot assert local_cnt == 0 here, as get_ldev_if_state will
 	 * inc/dec it frequently. Once we are D_DISKLESS, no one will touch
-	 * the protected members anymore, though, so in the after_state_ch work
-	 * it will be safe to free them. */
+	 * the protected members anymore, though, so once put_ldev reaches zero
+	 * again, it will be safe to free them. */
 	drbd_force_state(mdev, NS(disk, D_DISKLESS));
-	/* We need to wait for return of references checked out while we still
-	 * have been D_FAILED, though (drbd_md_sync, bitmap io). */
-	wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
-
-	clear_bit(GO_DISKLESS, &mdev->flags);
 	return 1;
 }
 
@@ -3777,9 +3802,6 @@ void drbd_go_diskless(struct drbd_conf *mdev)
 	D_ASSERT(mdev->state.disk == D_FAILED);
 	if (!test_and_set_bit(GO_DISKLESS, &mdev->flags))
 		drbd_queue_work(&mdev->data.work, &mdev->go_diskless);
-		/* don't drbd_queue_work_front,
-		 * we need to serialize with the after_state_ch work
-		 * of the -> D_FAILED transition. */
 }
 
 /**
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 87925e97e613..29e5c70e4e26 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -870,6 +870,11 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 		retcode = ERR_DISK_CONFIGURED;
 		goto fail;
 	}
+	/* It may just now have detached because of IO error.  Make sure
+	 * drbd_ldev_destroy is done already, we may end up here very fast,
+	 * e.g. if someone calls attach from the on-io-error handler,
+	 * to realize a "hot spare" feature (not that I'd recommend that) */
+	wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
 
 	/* allocation not in the IO path, cqueue thread context */
 	nbc = kzalloc(sizeof(struct drbd_backing_dev), GFP_KERNEL);
@@ -1098,9 +1103,9 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	/* Reset the "barriers don't work" bits here, then force meta data to
 	 * be written, to ensure we determine if barriers are supported. */
 	if (nbc->dc.no_md_flush)
-		set_bit(MD_NO_BARRIER, &mdev->flags);
+		set_bit(MD_NO_FUA, &mdev->flags);
 	else
-		clear_bit(MD_NO_BARRIER, &mdev->flags);
+		clear_bit(MD_NO_FUA, &mdev->flags);
 
 	/* Point of no return reached.
 	 * Devices and memory are no longer released by error cleanup below.
@@ -1112,8 +1117,8 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	nbc = NULL;
 	resync_lru = NULL;
 
-	mdev->write_ordering = WO_bio_barrier;
-	drbd_bump_write_ordering(mdev, WO_bio_barrier);
+	mdev->write_ordering = WO_bdev_flush;
+	drbd_bump_write_ordering(mdev, WO_bdev_flush);
 
 	if (drbd_md_test_flag(mdev->ldev, MDF_CRASHED_PRIMARY))
 		set_bit(CRASHED_PRIMARY, &mdev->flags);
@@ -1262,7 +1267,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
  force_diskless_dec:
 	put_ldev(mdev);
  force_diskless:
-	drbd_force_state(mdev, NS(disk, D_DISKLESS));
+	drbd_force_state(mdev, NS(disk, D_FAILED));
 	drbd_md_sync(mdev);
  release_bdev2_fail:
 	if (nbc)
@@ -1285,10 +1290,19 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	return 0;
 }
 
+/* Detaching the disk is a process in multiple stages.  First we need to lock
+ * out application IO, in-flight IO, IO stuck in drbd_al_begin_io.
+ * Then we transition to D_DISKLESS, and wait for put_ldev() to return all
+ * internal references as well.
+ * Only then we have finally detached. */
 static int drbd_nl_detach(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
 			  struct drbd_nl_cfg_reply *reply)
 {
+	drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */
 	reply->ret_code = drbd_request_state(mdev, NS(disk, D_DISKLESS));
+	if (mdev->state.disk == D_DISKLESS)
+		wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
+	drbd_resume_io(mdev);
 	return 0;
 }
 
@@ -1953,7 +1967,6 @@ static int drbd_nl_resume_io(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
 		drbd_uuid_new_current(mdev);
 		clear_bit(NEW_CUR_UUID, &mdev->flags);
-		drbd_md_sync(mdev);
 	}
 	drbd_suspend_io(mdev);
 	reply->ret_code = drbd_request_state(mdev, NS3(susp, 0, susp_nod, 0, susp_fen, 0));
diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c
index ad325c5d0ce1..7e6ac307e2de 100644
--- a/drivers/block/drbd/drbd_proc.c
+++ b/drivers/block/drbd/drbd_proc.c
@@ -158,7 +158,6 @@ static int drbd_seq_show(struct seq_file *seq, void *v)
 		[WO_none] = 'n',
 		[WO_drain_io] = 'd',
 		[WO_bdev_flush] = 'f',
-		[WO_bio_barrier] = 'b',
 	};
 
 	seq_printf(seq, "version: " REL_VERSION " (api:%d/proto:%d-%d)\n%s\n",
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index efd6169acf2f..d299fe9e78c8 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -49,11 +49,6 @@
 
 #include "drbd_vli.h"
 
-struct flush_work {
-	struct drbd_work w;
-	struct drbd_epoch *epoch;
-};
-
 enum finish_epoch {
 	FE_STILL_LIVE,
 	FE_DESTROYED,
@@ -66,16 +61,6 @@ static int drbd_do_auth(struct drbd_conf *mdev);
 static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *, struct drbd_epoch *, enum epoch_event);
 static int e_end_block(struct drbd_conf *, struct drbd_work *, int);
 
-static struct drbd_epoch *previous_epoch(struct drbd_conf *mdev, struct drbd_epoch *epoch)
-{
-	struct drbd_epoch *prev;
-	spin_lock(&mdev->epoch_lock);
-	prev = list_entry(epoch->list.prev, struct drbd_epoch, list);
-	if (prev == epoch || prev == mdev->current_epoch)
-		prev = NULL;
-	spin_unlock(&mdev->epoch_lock);
-	return prev;
-}
 
 #define GFP_TRY	(__GFP_HIGHMEM | __GFP_NOWARN)
 
@@ -981,7 +966,7 @@ static int drbd_recv_header(struct drbd_conf *mdev, enum drbd_packets *cmd, unsi
 	return TRUE;
 }
 
-static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct drbd_epoch *epoch)
+static void drbd_flush(struct drbd_conf *mdev)
 {
 	int rv;
 
@@ -997,24 +982,6 @@ static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct d
 		}
 		put_ldev(mdev);
 	}
-
-	return drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE);
-}
-
-static int w_flush(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
-{
-	struct flush_work *fw = (struct flush_work *)w;
-	struct drbd_epoch *epoch = fw->epoch;
-
-	kfree(w);
-
-	if (!test_and_set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags))
-		drbd_flush_after_epoch(mdev, epoch);
-
-	drbd_may_finish_epoch(mdev, epoch, EV_PUT |
-			      (mdev->state.conn < C_CONNECTED ? EV_CLEANUP : 0));
-
-	return 1;
 }
 
 /**
@@ -1027,15 +994,13 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
 					       struct drbd_epoch *epoch,
 					       enum epoch_event ev)
 {
-	int finish, epoch_size;
+	int epoch_size;
 	struct drbd_epoch *next_epoch;
-	int schedule_flush = 0;
 	enum finish_epoch rv = FE_STILL_LIVE;
 
 	spin_lock(&mdev->epoch_lock);
 	do {
 		next_epoch = NULL;
-		finish = 0;
 
 		epoch_size = atomic_read(&epoch->epoch_size);
 
@@ -1045,16 +1010,6 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
 			break;
 		case EV_GOT_BARRIER_NR:
 			set_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags);
-
-			/* Special case: If we just switched from WO_bio_barrier to
-			   WO_bdev_flush we should not finish the current epoch */
-			if (test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags) && epoch_size == 1 &&
-			    mdev->write_ordering != WO_bio_barrier &&
-			    epoch == mdev->current_epoch)
-				clear_bit(DE_CONTAINS_A_BARRIER, &epoch->flags);
-			break;
-		case EV_BARRIER_DONE:
-			set_bit(DE_BARRIER_IN_NEXT_EPOCH_DONE, &epoch->flags);
 			break;
 		case EV_BECAME_LAST:
 			/* nothing to do*/
@@ -1063,23 +1018,7 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
 
 		if (epoch_size != 0 &&
 		    atomic_read(&epoch->active) == 0 &&
-		    test_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags) &&
-		    epoch->list.prev == &mdev->current_epoch->list &&
-		    !test_bit(DE_IS_FINISHING, &epoch->flags)) {
-			/* Nearly all conditions are met to finish that epoch... */
-			if (test_bit(DE_BARRIER_IN_NEXT_EPOCH_DONE, &epoch->flags) ||
-			    mdev->write_ordering == WO_none ||
-			    (epoch_size == 1 && test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags)) ||
-			    ev & EV_CLEANUP) {
-				finish = 1;
-				set_bit(DE_IS_FINISHING, &epoch->flags);
-			} else if (!test_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags) &&
-				 mdev->write_ordering == WO_bio_barrier) {
-				atomic_inc(&epoch->active);
-				schedule_flush = 1;
-			}
-		}
-		if (finish) {
+		    test_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags)) {
 			if (!(ev & EV_CLEANUP)) {
 				spin_unlock(&mdev->epoch_lock);
 				drbd_send_b_ack(mdev, epoch->barrier_nr, epoch_size);
@@ -1102,6 +1041,7 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
 				/* atomic_set(&epoch->active, 0); is already zero */
 				if (rv == FE_STILL_LIVE)
 					rv = FE_RECYCLED;
+				wake_up(&mdev->ee_wait);
 			}
 		}
 
@@ -1113,22 +1053,6 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
 
 	spin_unlock(&mdev->epoch_lock);
 
-	if (schedule_flush) {
-		struct flush_work *fw;
-		fw = kmalloc(sizeof(*fw), GFP_ATOMIC);
-		if (fw) {
-			fw->w.cb = w_flush;
-			fw->epoch = epoch;
-			drbd_queue_work(&mdev->data.work, &fw->w);
-		} else {
-			dev_warn(DEV, "Could not kmalloc a flush_work obj\n");
-			set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags);
-			/* That is not a recursion, only one level */
-			drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE);
-			drbd_may_finish_epoch(mdev, epoch, EV_PUT);
-		}
-	}
-
 	return rv;
 }
 
@@ -1144,19 +1068,16 @@ void drbd_bump_write_ordering(struct drbd_conf *mdev, enum write_ordering_e wo)
 		[WO_none] = "none",
 		[WO_drain_io] = "drain",
 		[WO_bdev_flush] = "flush",
-		[WO_bio_barrier] = "barrier",
 	};
 
 	pwo = mdev->write_ordering;
 	wo = min(pwo, wo);
-	if (wo == WO_bio_barrier && mdev->ldev->dc.no_disk_barrier)
-		wo = WO_bdev_flush;
 	if (wo == WO_bdev_flush && mdev->ldev->dc.no_disk_flush)
 		wo = WO_drain_io;
 	if (wo == WO_drain_io && mdev->ldev->dc.no_disk_drain)
 		wo = WO_none;
 	mdev->write_ordering = wo;
-	if (pwo != mdev->write_ordering || wo == WO_bio_barrier)
+	if (pwo != mdev->write_ordering || wo == WO_bdev_flush)
 		dev_info(DEV, "Method to ensure write ordering: %s\n", write_ordering_str[mdev->write_ordering]);
 }
 
@@ -1192,7 +1113,7 @@ next_bio:
 	bio->bi_sector = sector;
 	bio->bi_bdev = mdev->ldev->backing_bdev;
 	/* we special case some flags in the multi-bio case, see below
-	 * (REQ_UNPLUG, REQ_HARDBARRIER) */
+	 * (REQ_UNPLUG) */
 	bio->bi_rw = rw;
 	bio->bi_private = e;
 	bio->bi_end_io = drbd_endio_sec;
@@ -1226,11 +1147,6 @@ next_bio:
 			bio->bi_rw &= ~REQ_UNPLUG;
 
 		drbd_generic_make_request(mdev, fault_type, bio);
-
-		/* strip off REQ_HARDBARRIER,
-		 * unless it is the first or last bio */
-		if (bios && bios->bi_next)
-			bios->bi_rw &= ~REQ_HARDBARRIER;
 	} while (bios);
 	maybe_kick_lo(mdev);
 	return 0;
@@ -1244,45 +1160,9 @@ fail:
 	return -ENOMEM;
 }
 
-/**
- * w_e_reissue() - Worker callback; Resubmit a bio, without REQ_HARDBARRIER set
- * @mdev:	DRBD device.
- * @w:		work object.
- * @cancel:	The connection will be closed anyways (unused in this callback)
- */
-int w_e_reissue(struct drbd_conf *mdev, struct drbd_work *w, int cancel) __releases(local)
-{
-	struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
-	/* We leave DE_CONTAINS_A_BARRIER and EE_IS_BARRIER in place,
-	   (and DE_BARRIER_IN_NEXT_EPOCH_ISSUED in the previous Epoch)
-	   so that we can finish that epoch in drbd_may_finish_epoch().
-	   That is necessary if we already have a long chain of Epochs, before
-	   we realize that REQ_HARDBARRIER is actually not supported */
-
-	/* As long as the -ENOTSUPP on the barrier is reported immediately
-	   that will never trigger. If it is reported late, we will just
-	   print that warning and continue correctly for all future requests
-	   with WO_bdev_flush */
-	if (previous_epoch(mdev, e->epoch))
-		dev_warn(DEV, "Write ordering was not enforced (one time event)\n");
-
-	/* we still have a local reference,
-	 * get_ldev was done in receive_Data. */
-
-	e->w.cb = e_end_block;
-	if (drbd_submit_ee(mdev, e, WRITE, DRBD_FAULT_DT_WR) != 0) {
-		/* drbd_submit_ee fails for one reason only:
-		 * if was not able to allocate sufficient bios.
-		 * requeue, try again later. */
-		e->w.cb = w_e_reissue;
-		drbd_queue_work(&mdev->data.work, &e->w);
-	}
-	return 1;
-}
-
 static int receive_Barrier(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned int data_size)
 {
-	int rv, issue_flush;
+	int rv;
 	struct p_barrier *p = &mdev->data.rbuf.barrier;
 	struct drbd_epoch *epoch;
 
@@ -1300,44 +1180,40 @@ static int receive_Barrier(struct drbd_conf *mdev, enum drbd_packets cmd, unsign
 	 * Therefore we must send the barrier_ack after the barrier request was
 	 * completed. */
 	switch (mdev->write_ordering) {
-	case WO_bio_barrier:
 	case WO_none:
 		if (rv == FE_RECYCLED)
 			return TRUE;
-		break;
+
+		/* receiver context, in the writeout path of the other node.
+		 * avoid potential distributed deadlock */
+		epoch = kmalloc(sizeof(struct drbd_epoch), GFP_NOIO);
+		if (epoch)
+			break;
+		else
+			dev_warn(DEV, "Allocation of an epoch failed, slowing down\n");
+			/* Fall through */
 
 	case WO_bdev_flush:
 	case WO_drain_io:
-		if (rv == FE_STILL_LIVE) {
-			set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &mdev->current_epoch->flags);
-			drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
-			rv = drbd_flush_after_epoch(mdev, mdev->current_epoch);
-		}
-		if (rv == FE_RECYCLED)
-			return TRUE;
-
-		/* The asender will send all the ACKs and barrier ACKs out, since
-		   all EEs moved from the active_ee to the done_ee. We need to
-		   provide a new epoch object for the EEs that come in soon */
-		break;
-	}
-
-	/* receiver context, in the writeout path of the other node.
-	 * avoid potential distributed deadlock */
-	epoch = kmalloc(sizeof(struct drbd_epoch), GFP_NOIO);
-	if (!epoch) {
-		dev_warn(DEV, "Allocation of an epoch failed, slowing down\n");
-		issue_flush = !test_and_set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &mdev->current_epoch->flags);
 		drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
-		if (issue_flush) {
-			rv = drbd_flush_after_epoch(mdev, mdev->current_epoch);
-			if (rv == FE_RECYCLED)
-				return TRUE;
+		drbd_flush(mdev);
+
+		if (atomic_read(&mdev->current_epoch->epoch_size)) {
+			epoch = kmalloc(sizeof(struct drbd_epoch), GFP_NOIO);
+			if (epoch)
+				break;
 		}
 
-		drbd_wait_ee_list_empty(mdev, &mdev->done_ee);
+		epoch = mdev->current_epoch;
+		wait_event(mdev->ee_wait, atomic_read(&epoch->epoch_size) == 0);
+
+		D_ASSERT(atomic_read(&epoch->active) == 0);
+		D_ASSERT(epoch->flags == 0);
 
 		return TRUE;
+	default:
+		dev_err(DEV, "Strangeness in mdev->write_ordering %d\n", mdev->write_ordering);
+		return FALSE;
 	}
 
 	epoch->flags = 0;
@@ -1652,15 +1528,8 @@ static int e_end_block(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 {
 	struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
 	sector_t sector = e->sector;
-	struct drbd_epoch *epoch;
 	int ok = 1, pcmd;
 
-	if (e->flags & EE_IS_BARRIER) {
-		epoch = previous_epoch(mdev, e->epoch);
-		if (epoch)
-			drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE + (cancel ? EV_CLEANUP : 0));
-	}
-
 	if (mdev->net_conf->wire_protocol == DRBD_PROT_C) {
 		if (likely((e->flags & EE_WAS_ERROR) == 0)) {
 			pcmd = (mdev->state.conn >= C_SYNC_SOURCE &&
@@ -1817,27 +1686,6 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 	e->epoch = mdev->current_epoch;
 	atomic_inc(&e->epoch->epoch_size);
 	atomic_inc(&e->epoch->active);
-
-	if (mdev->write_ordering == WO_bio_barrier && atomic_read(&e->epoch->epoch_size) == 1) {
-		struct drbd_epoch *epoch;
-		/* Issue a barrier if we start a new epoch, and the previous epoch
-		   was not a epoch containing a single request which already was
-		   a Barrier. */
-		epoch = list_entry(e->epoch->list.prev, struct drbd_epoch, list);
-		if (epoch == e->epoch) {
-			set_bit(DE_CONTAINS_A_BARRIER, &e->epoch->flags);
-			rw |= REQ_HARDBARRIER;
-			e->flags |= EE_IS_BARRIER;
-		} else {
-			if (atomic_read(&epoch->epoch_size) > 1 ||
-			    !test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags)) {
-				set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags);
-				set_bit(DE_CONTAINS_A_BARRIER, &e->epoch->flags);
-				rw |= REQ_HARDBARRIER;
-				e->flags |= EE_IS_BARRIER;
-			}
-		}
-	}
 	spin_unlock(&mdev->epoch_lock);
 
 	dp_flags = be32_to_cpu(p->dp_flags);
@@ -1995,10 +1843,11 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 		break;
 	}
 
-	if (mdev->state.pdsk == D_DISKLESS) {
+	if (mdev->state.pdsk < D_INCONSISTENT) {
 		/* In case we have the only disk of the cluster, */
 		drbd_set_out_of_sync(mdev, e->sector, e->size);
 		e->flags |= EE_CALL_AL_COMPLETE_IO;
+		e->flags &= ~EE_MAY_SET_IN_SYNC;
 		drbd_al_begin_io(mdev, e->sector);
 	}
 
@@ -3362,7 +3211,7 @@ static int receive_state(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
 		if (ns.conn == C_MASK) {
 			ns.conn = C_CONNECTED;
 			if (mdev->state.disk == D_NEGOTIATING) {
-				drbd_force_state(mdev, NS(disk, D_DISKLESS));
+				drbd_force_state(mdev, NS(disk, D_FAILED));
 			} else if (peer_state.disk == D_NEGOTIATING) {
 				dev_err(DEV, "Disk attach process on the peer node was aborted.\n");
 				peer_state.disk = D_DISKLESS;
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 9e91a2545fc8..11a75d32a2e2 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -258,7 +258,7 @@ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
 		if (!hlist_unhashed(&req->colision))
 			hlist_del(&req->colision);
 		else
-			D_ASSERT((s & RQ_NET_MASK) == 0);
+			D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0);
 
 		/* for writes we need to do some extra housekeeping */
 		if (rw == WRITE)
@@ -813,7 +813,8 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio)
 			     mdev->state.conn >= C_CONNECTED));
 
 	if (!(local || remote) && !is_susp(mdev->state)) {
-		dev_err(DEV, "IO ERROR: neither local nor remote disk\n");
+		if (__ratelimit(&drbd_ratelimit_state))
+			dev_err(DEV, "IO ERROR: neither local nor remote disk\n");
 		goto fail_free_complete;
 	}
 
@@ -942,12 +943,21 @@ allocate_barrier:
 	if (local) {
 		req->private_bio->bi_bdev = mdev->ldev->backing_bdev;
 
-		if (FAULT_ACTIVE(mdev, rw == WRITE ? DRBD_FAULT_DT_WR
-				     : rw == READ  ? DRBD_FAULT_DT_RD
-				     :               DRBD_FAULT_DT_RA))
+		/* State may have changed since we grabbed our reference on the
+		 * mdev->ldev member. Double check, and short-circuit to endio.
+		 * In case the last activity log transaction failed to get on
+		 * stable storage, and this is a WRITE, we may not even submit
+		 * this bio. */
+		if (get_ldev(mdev)) {
+			if (FAULT_ACTIVE(mdev, rw == WRITE ? DRBD_FAULT_DT_WR
+					     : rw == READ  ? DRBD_FAULT_DT_RD
+					     :               DRBD_FAULT_DT_RA))
+				bio_endio(req->private_bio, -EIO);
+			else
+				generic_make_request(req->private_bio);
+			put_ldev(mdev);
+		} else
 			bio_endio(req->private_bio, -EIO);
-		else
-			generic_make_request(req->private_bio);
 	}
 
 	/* we need to plug ALWAYS since we possibly need to kick lo_dev.
@@ -1022,20 +1032,6 @@ int drbd_make_request_26(struct request_queue *q, struct bio *bio)
 		return 0;
 	}
 
-	/* Reject barrier requests if we know the underlying device does
-	 * not support them.
-	 * XXX: Need to get this info from peer as well some how so we
-	 * XXX: reject if EITHER side/data/metadata area does not support them.
-	 *
-	 * because of those XXX, this is not yet enabled,
-	 * i.e. in drbd_init_set_defaults we set the NO_BARRIER_SUPP bit.
-	 */
-	if (unlikely(bio->bi_rw & REQ_HARDBARRIER) && test_bit(NO_BARRIER_SUPP, &mdev->flags)) {
-		/* dev_warn(DEV, "Rejecting barrier request as underlying device does not support\n"); */
-		bio_endio(bio, -EOPNOTSUPP);
-		return 0;
-	}
-
 	/*
 	 * what we "blindly" assume:
 	 */
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 108d58015cd1..b0551ba7ad0c 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -102,12 +102,6 @@ void drbd_endio_read_sec_final(struct drbd_epoch_entry *e) __releases(local)
 	put_ldev(mdev);
 }
 
-static int is_failed_barrier(int ee_flags)
-{
-	return (ee_flags & (EE_IS_BARRIER|EE_WAS_ERROR|EE_RESUBMITTED))
-			== (EE_IS_BARRIER|EE_WAS_ERROR);
-}
-
 /* writes on behalf of the partner, or resync writes,
  * "submitted" by the receiver, final stage.  */
 static void drbd_endio_write_sec_final(struct drbd_epoch_entry *e) __releases(local)
@@ -119,21 +113,6 @@ static void drbd_endio_write_sec_final(struct drbd_epoch_entry *e) __releases(lo
 	int is_syncer_req;
 	int do_al_complete_io;
 
-	/* if this is a failed barrier request, disable use of barriers,
-	 * and schedule for resubmission */
-	if (is_failed_barrier(e->flags)) {
-		drbd_bump_write_ordering(mdev, WO_bdev_flush);
-		spin_lock_irqsave(&mdev->req_lock, flags);
-		list_del(&e->w.list);
-		e->flags = (e->flags & ~EE_WAS_ERROR) | EE_RESUBMITTED;
-		e->w.cb = w_e_reissue;
-		/* put_ldev actually happens below, once we come here again. */
-		__release(local);
-		spin_unlock_irqrestore(&mdev->req_lock, flags);
-		drbd_queue_work(&mdev->data.work, &e->w);
-		return;
-	}
-
 	D_ASSERT(e->block_id != ID_VACANT);
 
 	/* after we moved e to done_ee,
@@ -925,7 +904,7 @@ out:
 	drbd_md_sync(mdev);
 
 	if (test_and_clear_bit(WRITE_BM_AFTER_RESYNC, &mdev->flags)) {
-		dev_warn(DEV, "Writing the whole bitmap, due to failed kmalloc\n");
+		dev_info(DEV, "Writing the whole bitmap\n");
 		drbd_queue_bitmap_io(mdev, &drbd_bm_write, NULL, "write from resync_finished");
 	}