Merge tag 'for-linus-20180830' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Small collection of fixes that should go into this series. This pull
  contains:

   - NVMe pull request with three small fixes (via Christoph)

   - Kill useless NULL check before kmem_cache_destroy (Chengguang Xu)

   - Xen block driver pull request with persistent grant flushing fixes
     (Juergen Gross)

   - Final wbt fixes, wrapping up the changes for this series. These
     have been heavily tested (me)

   - cdrom info leak fix (Scott Bauer)

   - ATA dma quirk for SQ201 (Linus Walleij)

   - Straight forward bsg refcount_t conversion (John Pittman)"

* tag 'for-linus-20180830' of git://git.kernel.dk/linux-block:
  cdrom: Fix info leak/OOB read in cdrom_ioctl_drive_status
  nvmet: free workqueue object if module init fails
  nvme-fcloop: Fix dropped LS's to removed target port
  nvme-pci: add a memory barrier to nvme_dbbuf_update_and_check_event
  block: bsg: move atomic_t ref_count variable to refcount API
  block: remove unnecessary condition check
  ata: ftide010: Add a quirk for SQ201
  blk-wbt: remove dead code
  blk-wbt: improve waking of tasks
  blk-wbt: abstract out end IO completion handler
  xen/blkback: remove unused pers_gnts_lock from struct xen_blkif_ring
  xen/blkback: move persistent grants flags to bool
  xen/blkfront: reorder tests in xlblk_init()
  xen/blkfront: cleanup stale persistent grants
  xen/blkback: don't keep persistent grants too long

12 files changed, 269 insertions, 108 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkback b/Documentation/ABI/testing/sysfs-driver-xen-blkback
index 8bb43b66eb55..4e7babb3ba1f 100644
--- a/Documentation/ABI/testing/sysfs-driver-xen-blkback
+++ b/Documentation/ABI/testing/sysfs-driver-xen-blkback
@@ -15,3 +15,13 @@ Description:
                 blkback. If the frontend tries to use more than
                 max_persistent_grants, the LRU kicks in and starts
                 removing 5% of max_persistent_grants every 100ms.
+
+What:           /sys/module/xen_blkback/parameters/persistent_grant_unused_seconds
+Date:           August 2018
+KernelVersion:  4.19
+Contact:        Roger Pau Monné <roger.pau@citrix.com>
+Description:
+                How long a persistent grant is allowed to remain
+                allocated without being in use. The time is in
+                seconds, 0 means indefinitely long.
+                The default is 60 seconds.
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 84507d3e9a98..8e20a0677dcf 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -123,16 +123,11 @@ static void rwb_wake_all(struct rq_wb *rwb)
 	}
 }
 
-static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct)
+static void wbt_rqw_done(struct rq_wb *rwb, struct rq_wait *rqw,
+			 enum wbt_flags wb_acct)
 {
-	struct rq_wb *rwb = RQWB(rqos);
-	struct rq_wait *rqw;
 	int inflight, limit;
 
-	if (!(wb_acct & WBT_TRACKED))
-		return;
-
-	rqw = get_rq_wait(rwb, wb_acct);
 	inflight = atomic_dec_return(&rqw->inflight);
 
 	/*
@@ -166,10 +161,22 @@ static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct)
 		int diff = limit - inflight;
 
 		if (!inflight || diff >= rwb->wb_background / 2)
-			wake_up(&rqw->wait);
+			wake_up_all(&rqw->wait);
 	}
 }
 
+static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct)
+{
+	struct rq_wb *rwb = RQWB(rqos);
+	struct rq_wait *rqw;
+
+	if (!(wb_acct & WBT_TRACKED))
+		return;
+
+	rqw = get_rq_wait(rwb, wb_acct);
+	wbt_rqw_done(rwb, rqw, wb_acct);
+}
+
 /*
  * Called on completion of a request. Note that it's also called when
  * a request is merged, when the request gets freed.
@@ -481,6 +488,34 @@ static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw)
 	return limit;
 }
 
+struct wbt_wait_data {
+	struct wait_queue_entry wq;
+	struct task_struct *task;
+	struct rq_wb *rwb;
+	struct rq_wait *rqw;
+	unsigned long rw;
+	bool got_token;
+};
+
+static int wbt_wake_function(struct wait_queue_entry *curr, unsigned int mode,
+			     int wake_flags, void *key)
+{
+	struct wbt_wait_data *data = container_of(curr, struct wbt_wait_data,
+							wq);
+
+	/*
+	 * If we fail to get a budget, return -1 to interrupt the wake up
+	 * loop in __wake_up_common.
+	 */
+	if (!rq_wait_inc_below(data->rqw, get_limit(data->rwb, data->rw)))
+		return -1;
+
+	data->got_token = true;
+	list_del_init(&curr->entry);
+	wake_up_process(data->task);
+	return 1;
+}
+
 /*
  * Block if we will exceed our limit, or if we are currently waiting for
  * the timer to kick off queuing again.
@@ -491,19 +526,40 @@ static void __wbt_wait(struct rq_wb *rwb, enum wbt_flags wb_acct,
 	__acquires(lock)
 {
 	struct rq_wait *rqw = get_rq_wait(rwb, wb_acct);
-	DECLARE_WAITQUEUE(wait, current);
+	struct wbt_wait_data data = {
+		.wq = {
+			.func	= wbt_wake_function,
+			.entry	= LIST_HEAD_INIT(data.wq.entry),
+		},
+		.task = current,
+		.rwb = rwb,
+		.rqw = rqw,
+		.rw = rw,
+	};
 	bool has_sleeper;
 
 	has_sleeper = wq_has_sleeper(&rqw->wait);
 	if (!has_sleeper && rq_wait_inc_below(rqw, get_limit(rwb, rw)))
 		return;
 
-	add_wait_queue_exclusive(&rqw->wait, &wait);
+	prepare_to_wait_exclusive(&rqw->wait, &data.wq, TASK_UNINTERRUPTIBLE);
 	do {
-		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (data.got_token)
+			break;
 
-		if (!has_sleeper && rq_wait_inc_below(rqw, get_limit(rwb, rw)))
+		if (!has_sleeper &&
+		    rq_wait_inc_below(rqw, get_limit(rwb, rw))) {
+			finish_wait(&rqw->wait, &data.wq);
+
+			/*
+			 * We raced with wbt_wake_function() getting a token,
+			 * which means we now have two. Put our local token
+			 * and wake anyone else potentially waiting for one.
+			 */
+			if (data.got_token)
+				wbt_rqw_done(rwb, rqw, wb_acct);
 			break;
+		}
 
 		if (lock) {
 			spin_unlock_irq(lock);
@@ -511,11 +567,11 @@ static void __wbt_wait(struct rq_wb *rwb, enum wbt_flags wb_acct,
 			spin_lock_irq(lock);
 		} else
 			io_schedule();
+
 		has_sleeper = false;
 	} while (1);
 
-	__set_current_state(TASK_RUNNING);
-	remove_wait_queue(&rqw->wait, &wait);
+	finish_wait(&rqw->wait, &data.wq);
 }
 
 static inline bool wbt_should_throttle(struct rq_wb *rwb, struct bio *bio)
@@ -580,11 +636,6 @@ static void wbt_wait(struct rq_qos *rqos, struct bio *bio, spinlock_t *lock)
 		return;
 	}
 
-	if (current_is_kswapd())
-		flags |= WBT_KSWAPD;
-	if (bio_op(bio) == REQ_OP_DISCARD)
-		flags |= WBT_DISCARD;
-
 	__wbt_wait(rwb, flags, bio->bi_opf, lock);
 
 	if (!blk_stat_is_active(rwb->cb))
diff --git a/block/bsg.c b/block/bsg.c
index db588add6ba6..9a442c23a715 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -37,7 +37,7 @@ struct bsg_device {
 	struct request_queue *queue;
 	spinlock_t lock;
 	struct hlist_node dev_list;
-	atomic_t ref_count;
+	refcount_t ref_count;
 	char name[20];
 	int max_queue;
 };
@@ -252,7 +252,7 @@ static int bsg_put_device(struct bsg_device *bd)
 
 	mutex_lock(&bsg_mutex);
 
-	if (!atomic_dec_and_test(&bd->ref_count)) {
+	if (!refcount_dec_and_test(&bd->ref_count)) {
 		mutex_unlock(&bsg_mutex);
 		return 0;
 	}
@@ -290,7 +290,7 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
 
 	bd->queue = rq;
 
-	atomic_set(&bd->ref_count, 1);
+	refcount_set(&bd->ref_count, 1);
 	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 
 	strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
@@ -308,7 +308,7 @@ static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 
 	hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
 		if (bd->queue == q) {
-			atomic_inc(&bd->ref_count);
+			refcount_inc(&bd->ref_count);
 			goto found;
 		}
 	}
diff --git a/block/elevator.c b/block/elevator.c
index 5ea6e7d600e4..6a06b5d040e5 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -895,8 +895,7 @@ int elv_register(struct elevator_type *e)
 	spin_lock(&elv_list_lock);
 	if (elevator_find(e->elevator_name, e->uses_mq)) {
 		spin_unlock(&elv_list_lock);
-		if (e->icq_cache)
-			kmem_cache_destroy(e->icq_cache);
+		kmem_cache_destroy(e->icq_cache);
 		return -EBUSY;
 	}
 	list_add_tail(&e->list, &elv_list);
diff --git a/drivers/ata/pata_ftide010.c b/drivers/ata/pata_ftide010.c
index 5d4b72e21161..569a4a662dcd 100644
--- a/drivers/ata/pata_ftide010.c
+++ b/drivers/ata/pata_ftide010.c
@@ -256,14 +256,12 @@ static struct ata_port_operations pata_ftide010_port_ops = {
 	.qc_issue	= ftide010_qc_issue,
 };
 
-static struct ata_port_info ftide010_port_info[] = {
-	{
-		.flags		= ATA_FLAG_SLAVE_POSS,
-		.mwdma_mask	= ATA_MWDMA2,
-		.udma_mask	= ATA_UDMA6,
-		.pio_mask	= ATA_PIO4,
-		.port_ops	= &pata_ftide010_port_ops,
-	},
+static struct ata_port_info ftide010_port_info = {
+	.flags		= ATA_FLAG_SLAVE_POSS,
+	.mwdma_mask	= ATA_MWDMA2,
+	.udma_mask	= ATA_UDMA6,
+	.pio_mask	= ATA_PIO4,
+	.port_ops	= &pata_ftide010_port_ops,
 };
 
 #if IS_ENABLED(CONFIG_SATA_GEMINI)
@@ -349,6 +347,7 @@ static int pata_ftide010_gemini_cable_detect(struct ata_port *ap)
 }
 
 static int pata_ftide010_gemini_init(struct ftide010 *ftide,
+				     struct ata_port_info *pi,
 				     bool is_ata1)
 {
 	struct device *dev = ftide->dev;
@@ -373,7 +372,13 @@ static int pata_ftide010_gemini_init(struct ftide010 *ftide,
 
 	/* Flag port as SATA-capable */
 	if (gemini_sata_bridge_enabled(sg, is_ata1))
-		ftide010_port_info[0].flags |= ATA_FLAG_SATA;
+		pi->flags |= ATA_FLAG_SATA;
+
+	/* This device has broken DMA, only PIO works */
+	if (of_machine_is_compatible("itian,sq201")) {
+		pi->mwdma_mask = 0;
+		pi->udma_mask = 0;
+	}
 
 	/*
 	 * We assume that a simple 40-wire cable is used in the PATA mode.
@@ -435,6 +440,7 @@ static int pata_ftide010_gemini_init(struct ftide010 *ftide,
 }
 #else
 static int pata_ftide010_gemini_init(struct ftide010 *ftide,
+				     struct ata_port_info *pi,
 				     bool is_ata1)
 {
 	return -ENOTSUPP;
@@ -446,7 +452,7 @@ static int pata_ftide010_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
-	const struct ata_port_info pi = ftide010_port_info[0];
+	struct ata_port_info pi = ftide010_port_info;
 	const struct ata_port_info *ppi[] = { &pi, NULL };
 	struct ftide010 *ftide;
 	struct resource *res;
@@ -490,6 +496,7 @@ static int pata_ftide010_probe(struct platform_device *pdev)
 		 * are ATA0. This will also set up the cable types.
 		 */
 		ret = pata_ftide010_gemini_init(ftide,
+				&pi,
 				(res->start == 0x63400000));
 		if (ret)
 			goto err_dis_clk;
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index b55b245e8052..fd1e19f1a49f 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -84,6 +84,18 @@ MODULE_PARM_DESC(max_persistent_grants,
                  "Maximum number of grants to map persistently");
 
 /*
+ * How long a persistent grant is allowed to remain allocated without being in
+ * use. The time is in seconds, 0 means indefinitely long.
+ */
+
+static unsigned int xen_blkif_pgrant_timeout = 60;
+module_param_named(persistent_grant_unused_seconds, xen_blkif_pgrant_timeout,
+		   uint, 0644);
+MODULE_PARM_DESC(persistent_grant_unused_seconds,
+		 "Time in seconds an unused persistent grant is allowed to "
+		 "remain allocated. Default is 60, 0 means unlimited.");
+
+/*
  * Maximum number of rings/queues blkback supports, allow as many queues as there
  * are CPUs if user has not specified a value.
  */
@@ -123,6 +135,13 @@ module_param(log_stats, int, 0644);
 /* Number of free pages to remove on each call to gnttab_free_pages */
 #define NUM_BATCH_FREE_PAGES 10
 
+static inline bool persistent_gnt_timeout(struct persistent_gnt *persistent_gnt)
+{
+	return xen_blkif_pgrant_timeout &&
+	       (jiffies - persistent_gnt->last_used >=
+		HZ * xen_blkif_pgrant_timeout);
+}
+
 static inline int get_free_page(struct xen_blkif_ring *ring, struct page **page)
 {
 	unsigned long flags;
@@ -236,8 +255,7 @@ static int add_persistent_gnt(struct xen_blkif_ring *ring,
 		}
 	}
 
-	bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE);
-	set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
+	persistent_gnt->active = true;
 	/* Add new node and rebalance tree. */
 	rb_link_node(&(persistent_gnt->node), parent, new);
 	rb_insert_color(&(persistent_gnt->node), &ring->persistent_gnts);
@@ -261,11 +279,11 @@ static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring,
 		else if (gref > data->gnt)
 			node = node->rb_right;
 		else {
-			if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) {
+			if (data->active) {
 				pr_alert_ratelimited("requesting a grant already in use\n");
 				return NULL;
 			}
-			set_bit(PERSISTENT_GNT_ACTIVE, data->flags);
+			data->active = true;
 			atomic_inc(&ring->persistent_gnt_in_use);
 			return data;
 		}
@@ -276,10 +294,10 @@ static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring,
 static void put_persistent_gnt(struct xen_blkif_ring *ring,
                                struct persistent_gnt *persistent_gnt)
 {
-	if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
+	if (!persistent_gnt->active)
 		pr_alert_ratelimited("freeing a grant already unused\n");
-	set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
-	clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
+	persistent_gnt->last_used = jiffies;
+	persistent_gnt->active = false;
 	atomic_dec(&ring->persistent_gnt_in_use);
 }
 
@@ -371,26 +389,26 @@ static void purge_persistent_gnt(struct xen_blkif_ring *ring)
 	struct persistent_gnt *persistent_gnt;
 	struct rb_node *n;
 	unsigned int num_clean, total;
-	bool scan_used = false, clean_used = false;
+	bool scan_used = false;
 	struct rb_root *root;
 
-	if (ring->persistent_gnt_c < xen_blkif_max_pgrants ||
-	    (ring->persistent_gnt_c == xen_blkif_max_pgrants &&
-	    !ring->blkif->vbd.overflow_max_grants)) {
-		goto out;
-	}
-
 	if (work_busy(&ring->persistent_purge_work)) {
 		pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n");
 		goto out;
 	}
 
-	num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
-	num_clean = ring->persistent_gnt_c - xen_blkif_max_pgrants + num_clean;
-	num_clean = min(ring->persistent_gnt_c, num_clean);
-	if ((num_clean == 0) ||
-	    (num_clean > (ring->persistent_gnt_c - atomic_read(&ring->persistent_gnt_in_use))))
-		goto out;
+	if (ring->persistent_gnt_c < xen_blkif_max_pgrants ||
+	    (ring->persistent_gnt_c == xen_blkif_max_pgrants &&
+	    !ring->blkif->vbd.overflow_max_grants)) {
+		num_clean = 0;
+	} else {
+		num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
+		num_clean = ring->persistent_gnt_c - xen_blkif_max_pgrants +
+			    num_clean;
+		num_clean = min(ring->persistent_gnt_c, num_clean);
+		pr_debug("Going to purge at least %u persistent grants\n",
+			 num_clean);
+	}
 
 	/*
 	 * At this point, we can assure that there will be no calls
@@ -401,9 +419,7 @@ static void purge_persistent_gnt(struct xen_blkif_ring *ring)
          * number of grants.
 	 */
 
-	total = num_clean;
-
-	pr_debug("Going to purge %u persistent grants\n", num_clean);
+	total = 0;
 
 	BUG_ON(!list_empty(&ring->persistent_purge_list));
 	root = &ring->persistent_gnts;
@@ -412,46 +428,37 @@ purge_list:
 		BUG_ON(persistent_gnt->handle ==
 			BLKBACK_INVALID_HANDLE);
 
-		if (clean_used) {
-			clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
+		if (persistent_gnt->active)
 			continue;
-		}
-
-		if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
+		if (!scan_used && !persistent_gnt_timeout(persistent_gnt))
 			continue;
-		if (!scan_used &&
-		    (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags)))
+		if (scan_used && total >= num_clean)
 			continue;
 
 		rb_erase(&persistent_gnt->node, root);
 		list_add(&persistent_gnt->remove_node,
 			 &ring->persistent_purge_list);
-		if (--num_clean == 0)
-			goto finished;
+		total++;
 	}
 	/*
-	 * If we get here it means we also need to start cleaning
+	 * Check whether we also need to start cleaning
 	 * grants that were used since last purge in order to cope
 	 * with the requested num
 	 */
-	if (!scan_used && !clean_used) {
-		pr_debug("Still missing %u purged frames\n", num_clean);
+	if (!scan_used && total < num_clean) {
+		pr_debug("Still missing %u purged frames\n", num_clean - total);
 		scan_used = true;
 		goto purge_list;
 	}
-finished:
-	if (!clean_used) {
-		pr_debug("Finished scanning for grants to clean, removing used flag\n");
-		clean_used = true;
-		goto purge_list;
-	}
 
-	ring->persistent_gnt_c -= (total - num_clean);
-	ring->blkif->vbd.overflow_max_grants = 0;
+	if (total) {
+		ring->persistent_gnt_c -= total;
+		ring->blkif->vbd.overflow_max_grants = 0;
 
-	/* We can defer this work */
-	schedule_work(&ring->persistent_purge_work);
-	pr_debug("Purged %u/%u\n", (total - num_clean), total);
+		/* We can defer this work */
+		schedule_work(&ring->persistent_purge_work);
+		pr_debug("Purged %u/%u\n", num_clean, total);
+	}
 
 out:
 	return;
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index ecb35fe8ca8d..1d3002d773f7 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -233,16 +233,6 @@ struct xen_vbd {
 
 struct backend_info;
 
-/* Number of available flags */
-#define PERSISTENT_GNT_FLAGS_SIZE	2
-/* This persistent grant is currently in use */
-#define PERSISTENT_GNT_ACTIVE		0
-/*
- * This persistent grant has been used, this flag is set when we remove the
- * PERSISTENT_GNT_ACTIVE, to know that this grant has been used recently.
- */
-#define PERSISTENT_GNT_WAS_ACTIVE	1
-
 /* Number of requests that we can fit in a ring */
 #define XEN_BLKIF_REQS_PER_PAGE		32
 
@@ -250,7 +240,8 @@ struct persistent_gnt {
 	struct page *page;
 	grant_ref_t gnt;
 	grant_handle_t handle;
-	DECLARE_BITMAP(flags, PERSISTENT_GNT_FLAGS_SIZE);
+	unsigned long last_used;
+	bool active;
 	struct rb_node node;
 	struct list_head remove_node;
 };
@@ -278,7 +269,6 @@ struct xen_blkif_ring {
 	wait_queue_head_t	pending_free_wq;
 
 	/* Tree to store persistent grants. */
-	spinlock_t		pers_gnts_lock;
 	struct rb_root		persistent_gnts;
 	unsigned int		persistent_gnt_c;
 	atomic_t		persistent_gnt_in_use;
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 8986adab9bf5..a71d817e900d 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -46,6 +46,7 @@
 #include <linux/scatterlist.h>
 #include <linux/bitmap.h>
 #include <linux/list.h>
+#include <linux/workqueue.h>
 
 #include <xen/xen.h>
 #include <xen/xenbus.h>
@@ -121,6 +122,8 @@ static inline struct blkif_req *blkif_req(struct request *rq)
 
 static DEFINE_MUTEX(blkfront_mutex);
 static const struct block_device_operations xlvbd_block_fops;
+static struct delayed_work blkfront_work;
+static LIST_HEAD(info_list);
 
 /*
  * Maximum number of segments in indirect requests, the actual value used by
@@ -216,6 +219,7 @@ struct blkfront_info
 	/* Save uncomplete reqs and bios for migration. */
 	struct list_head requests;
 	struct bio_list bio_list;
+	struct list_head info_list;
 };
 
 static unsigned int nr_minors;
@@ -1759,6 +1763,12 @@ abort_transaction:
 	return err;
 }
 
+static void free_info(struct blkfront_info *info)
+{
+	list_del(&info->info_list);
+	kfree(info);
+}
+
 /* Common code used when first setting up, and when resuming. */
 static int talk_to_blkback(struct xenbus_device *dev,
 			   struct blkfront_info *info)
@@ -1880,7 +1890,10 @@ again:
  destroy_blkring:
 	blkif_free(info, 0);
 
-	kfree(info);
+	mutex_lock(&blkfront_mutex);
+	free_info(info);
+	mutex_unlock(&blkfront_mutex);
+
 	dev_set_drvdata(&dev->dev, NULL);
 
 	return err;
@@ -1991,6 +2004,10 @@ static int blkfront_probe(struct xenbus_device *dev,
 	info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
 	dev_set_drvdata(&dev->dev, info);
 
+	mutex_lock(&blkfront_mutex);
+	list_add(&info->info_list, &info_list);
+	mutex_unlock(&blkfront_mutex);
+
 	return 0;
 }
 
@@ -2301,6 +2318,12 @@ static void blkfront_gather_backend_features(struct blkfront_info *info)
 	if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
 		indirect_segments = 0;
 	info->max_indirect_segments = indirect_segments;
+
+	if (info->feature_persistent) {
+		mutex_lock(&blkfront_mutex);
+		schedule_delayed_work(&blkfront_work, HZ * 10);
+		mutex_unlock(&blkfront_mutex);
+	}
 }
 
 /*
@@ -2482,7 +2505,9 @@ static int blkfront_remove(struct xenbus_device *xbdev)
 	mutex_unlock(&info->mutex);
 
 	if (!bdev) {
-		kfree(info);
+		mutex_lock(&blkfront_mutex);
+		free_info(info);
+		mutex_unlock(&blkfront_mutex);
 		return 0;
 	}
 
@@ -2502,7 +2527,9 @@ static int blkfront_remove(struct xenbus_device *xbdev)
 	if (info && !bdev->bd_openers) {
 		xlvbd_release_gendisk(info);
 		disk->private_data = NULL;
-		kfree(info);
+		mutex_lock(&blkfront_mutex);
+		free_info(info);
+		mutex_unlock(&blkfront_mutex);
 	}
 
 	mutex_unlock(&bdev->bd_mutex);
@@ -2585,7 +2612,7 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 		dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
 		xlvbd_release_gendisk(info);
 		disk->private_data = NULL;
-		kfree(info);
+		free_info(info);
 	}
 
 out:
@@ -2618,6 +2645,61 @@ static struct xenbus_driver blkfront_driver = {
 	.is_ready = blkfront_is_ready,
 };
 
+static void purge_persistent_grants(struct blkfront_info *info)
+{
+	unsigned int i;
+	unsigned long flags;
+
+	for (i = 0; i < info->nr_rings; i++) {
+		struct blkfront_ring_info *rinfo = &info->rinfo[i];
+		struct grant *gnt_list_entry, *tmp;
+
+		spin_lock_irqsave(&rinfo->ring_lock, flags);
+
+		if (rinfo->persistent_gnts_c == 0) {
+			spin_unlock_irqrestore(&rinfo->ring_lock, flags);
+			continue;
+		}
+
+		list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
+					 node) {
+			if (gnt_list_entry->gref == GRANT_INVALID_REF ||
+			    gnttab_query_foreign_access(gnt_list_entry->gref))
+				continue;
+
+			list_del(&gnt_list_entry->node);
+			gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
+			rinfo->persistent_gnts_c--;
+			__free_page(gnt_list_entry->page);
+			kfree(gnt_list_entry);
+		}
+
+		spin_unlock_irqrestore(&rinfo->ring_lock, flags);
+	}
+}
+
+static void blkfront_delay_work(struct work_struct *work)
+{
+	struct blkfront_info *info;
+	bool need_schedule_work = false;
+
+	mutex_lock(&blkfront_mutex);
+
+	list_for_each_entry(info, &info_list, info_list) {
+		if (info->feature_persistent) {
+			need_schedule_work = true;
+			mutex_lock(&info->mutex);
+			purge_persistent_grants(info);
+			mutex_unlock(&info->mutex);
+		}
+	}
+
+	if (need_schedule_work)
+		schedule_delayed_work(&blkfront_work, HZ * 10);
+
+	mutex_unlock(&blkfront_mutex);
+}
+
 static int __init xlblk_init(void)
 {
 	int ret;
@@ -2626,6 +2708,15 @@ static int __init xlblk_init(void)
 	if (!xen_domain())
 		return -ENODEV;
 
+	if (!xen_has_pv_disk_devices())
+		return -ENODEV;
+
+	if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
+		pr_warn("xen_blk: can't get major %d with name %s\n",
+			XENVBD_MAJOR, DEV_NAME);
+		return -ENODEV;
+	}
+
 	if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
 		xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 
@@ -2641,14 +2732,7 @@ static int __init xlblk_init(void)
 		xen_blkif_max_queues = nr_cpus;
 	}
 
-	if (!xen_has_pv_disk_devices())
-		return -ENODEV;
-
-	if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
-		printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
-		       XENVBD_MAJOR, DEV_NAME);
-		return -ENODEV;
-	}
+	INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
 
 	ret = xenbus_register_frontend(&blkfront_driver);
 	if (ret) {
@@ -2663,6 +2747,8 @@ module_init(xlblk_init);
 
 static void __exit xlblk_exit(void)
 {
+	cancel_delayed_work_sync(&blkfront_work);
+
 	xenbus_unregister_driver(&blkfront_driver);
 	unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
 	kfree(minors);
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 113fc6edb2b0..a5d5a96479bf 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2546,7 +2546,7 @@ static int cdrom_ioctl_drive_status(struct cdrom_device_info *cdi,
 	if (!CDROM_CAN(CDC_SELECT_DISC) ||
 	    (arg == CDSL_CURRENT || arg == CDSL_NONE))
 		return cdi->ops->drive_status(cdi, CDSL_CURRENT);
-	if (((int)arg >= cdi->capacity))
+	if (arg >= cdi->capacity)
 		return -EINVAL;
 	return cdrom_slot_status(cdi, arg);
 }
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 1b9951d2067e..d668682f91df 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -316,6 +316,14 @@ static bool nvme_dbbuf_update_and_check_event(u16 value, u32 *dbbuf_db,
 		old_value = *dbbuf_db;
 		*dbbuf_db = value;
 
+		/*
+		 * Ensure that the doorbell is updated before reading the event
+		 * index from memory.  The controller needs to provide similar
+		 * ordering to ensure the envent index is updated before reading
+		 * the doorbell.
+		 */
+		mb();
+
 		if (!nvme_dbbuf_need_event(*dbbuf_ei, value, old_value))
 			return false;
 	}
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index ebf3e7a6c49e..b5ec96abd048 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1210,7 +1210,7 @@ static int __init nvmet_init(void)
 
 	error = nvmet_init_discovery();
 	if (error)
-		goto out;
+		goto out_free_work_queue;
 
 	error = nvmet_init_configfs();
 	if (error)
@@ -1219,6 +1219,8 @@ static int __init nvmet_init(void)
 
 out_exit_discovery:
 	nvmet_exit_discovery();
+out_free_work_queue:
+	destroy_workqueue(buffered_io_wq);
 out:
 	return error;
 }
diff --git a/drivers/nvme/target/fcloop.c b/drivers/nvme/target/fcloop.c
index 34712def81b1..5251689a1d9a 100644
--- a/drivers/nvme/target/fcloop.c
+++ b/drivers/nvme/target/fcloop.c
@@ -311,7 +311,7 @@ fcloop_tgt_lsrqst_done_work(struct work_struct *work)
 	struct fcloop_tport *tport = tls_req->tport;
 	struct nvmefc_ls_req *lsreq = tls_req->lsreq;
 
-	if (tport->remoteport)
+	if (!tport || tport->remoteport)
 		lsreq->done(lsreq, tls_req->status);
 }
 
@@ -329,6 +329,7 @@ fcloop_ls_req(struct nvme_fc_local_port *localport,
 
 	if (!rport->targetport) {
 		tls_req->status = -ECONNREFUSED;
+		tls_req->tport = NULL;
 		schedule_work(&tls_req->work);
 		return ret;
 	}