Merge tag 'for-4.17/block-20180402' of git://git.kernel.dk/linux-block

Pull block layer updates from Jens Axboe:
 "It's a pretty quiet round this time, which is nice. This contains:

   - series from Bart, cleaning up the way we set/test/clear atomic
     queue flags.

   - series from Bart, fixing races between gendisk and queue
     registration and removal.

   - set of bcache fixes and improvements from various folks, by way of
     Michael Lyle.

   - set of lightnvm updates from Matias, most of it being the 1.2 to
     2.0 transition.

   - removal of unused DIO flags from Nikolay.

   - blk-mq/sbitmap memory ordering fixes from Omar.

   - divide-by-zero fix for BFQ from Paolo.

   - minor documentation patches from Randy.

   - timeout fix from Tejun.

   - Alpha "can't write a char atomically" fix from Mikulas.

   - set of NVMe fixes by way of Keith.

   - bsg and bsg-lib improvements from Christoph.

   - a few sed-opal fixes from Jonas.

   - cdrom check-disk-change deadlock fix from Maurizio.

   - various little fixes, comment fixes, etc from various folks"

* tag 'for-4.17/block-20180402' of git://git.kernel.dk/linux-block: (139 commits)
  blk-mq: Directly schedule q->timeout_work when aborting a request
  blktrace: fix comment in blktrace_api.h
  lightnvm: remove function name in strings
  lightnvm: pblk: remove some unnecessary NULL checks
  lightnvm: pblk: don't recover unwritten lines
  lightnvm: pblk: implement 2.0 support
  lightnvm: pblk: implement get log report chunk
  lightnvm: pblk: rename ppaf* to addrf*
  lightnvm: pblk: check for supported version
  lightnvm: implement get log report chunk helpers
  lightnvm: make address conversions depend on generic device
  lightnvm: add support for 2.0 address format
  lightnvm: normalize geometry nomenclature
  lightnvm: complete geo structure with maxoc*
  lightnvm: add shorten OCSSD version in geo
  lightnvm: add minor version to generic geometry
  lightnvm: simplify geometry structure
  lightnvm: pblk: refactor init/exit sequences
  lightnvm: Avoid validation of default op value
  lightnvm: centralize permission check for lightnvm ioctl
  ...

26 files changed, 582 insertions, 155 deletions

diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
index 458e1d38577d..004cc3cc6123 100644
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -287,7 +287,8 @@ do {									\
 			break;						\
 									\
 		mutex_unlock(&(ca)->set->bucket_lock);			\
-		if (kthread_should_stop()) {				\
+		if (kthread_should_stop() ||				\
+		    test_bit(CACHE_SET_IO_DISABLE, &ca->set->flags)) {	\
 			set_current_state(TASK_RUNNING);		\
 			return 0;					\
 		}							\
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 12e5197f186c..d338b7086013 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -188,6 +188,7 @@
 #include <linux/refcount.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
+#include <linux/kthread.h>
 
 #include "bset.h"
 #include "util.h"
@@ -258,10 +259,11 @@ struct bcache_device {
 	struct gendisk		*disk;
 
 	unsigned long		flags;
-#define BCACHE_DEV_CLOSING	0
-#define BCACHE_DEV_DETACHING	1
-#define BCACHE_DEV_UNLINK_DONE	2
-
+#define BCACHE_DEV_CLOSING		0
+#define BCACHE_DEV_DETACHING		1
+#define BCACHE_DEV_UNLINK_DONE		2
+#define BCACHE_DEV_WB_RUNNING		3
+#define BCACHE_DEV_RATE_DW_RUNNING	4
 	unsigned		nr_stripes;
 	unsigned		stripe_size;
 	atomic_t		*stripe_sectors_dirty;
@@ -286,6 +288,12 @@ struct io {
 	sector_t		last;
 };
 
+enum stop_on_failure {
+	BCH_CACHED_DEV_STOP_AUTO = 0,
+	BCH_CACHED_DEV_STOP_ALWAYS,
+	BCH_CACHED_DEV_STOP_MODE_MAX,
+};
+
 struct cached_dev {
 	struct list_head	list;
 	struct bcache_device	disk;
@@ -359,6 +367,7 @@ struct cached_dev {
 	unsigned		sequential_cutoff;
 	unsigned		readahead;
 
+	unsigned		io_disable:1;
 	unsigned		verify:1;
 	unsigned		bypass_torture_test:1;
 
@@ -378,6 +387,11 @@ struct cached_dev {
 	unsigned		writeback_rate_i_term_inverse;
 	unsigned		writeback_rate_p_term_inverse;
 	unsigned		writeback_rate_minimum;
+
+	enum stop_on_failure	stop_when_cache_set_failed;
+#define DEFAULT_CACHED_DEV_ERROR_LIMIT	64
+	atomic_t		io_errors;
+	unsigned		error_limit;
 };
 
 enum alloc_reserve {
@@ -474,10 +488,15 @@ struct gc_stat {
  *
  * CACHE_SET_RUNNING means all cache devices have been registered and journal
  * replay is complete.
+ *
+ * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all
+ * external and internal I/O should be denied when this flag is set.
+ *
  */
 #define CACHE_SET_UNREGISTERING		0
 #define	CACHE_SET_STOPPING		1
 #define	CACHE_SET_RUNNING		2
+#define CACHE_SET_IO_DISABLE		3
 
 struct cache_set {
 	struct closure		cl;
@@ -867,8 +886,36 @@ static inline void wake_up_allocators(struct cache_set *c)
 		wake_up_process(ca->alloc_thread);
 }
 
+static inline void closure_bio_submit(struct cache_set *c,
+				      struct bio *bio,
+				      struct closure *cl)
+{
+	closure_get(cl);
+	if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) {
+		bio->bi_status = BLK_STS_IOERR;
+		bio_endio(bio);
+		return;
+	}
+	generic_make_request(bio);
+}
+
+/*
+ * Prevent the kthread exits directly, and make sure when kthread_stop()
+ * is called to stop a kthread, it is still alive. If a kthread might be
+ * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is
+ * necessary before the kthread returns.
+ */
+static inline void wait_for_kthread_stop(void)
+{
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+	}
+}
+
 /* Forward declarations */
 
+void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio);
 void bch_count_io_errors(struct cache *, blk_status_t, int, const char *);
 void bch_bbio_count_io_errors(struct cache_set *, struct bio *,
 			      blk_status_t, const char *);
@@ -896,6 +943,7 @@ int bch_bucket_alloc_set(struct cache_set *, unsigned,
 			 struct bkey *, int, bool);
 bool bch_alloc_sectors(struct cache_set *, struct bkey *, unsigned,
 		       unsigned, unsigned, bool);
+bool bch_cached_dev_error(struct cached_dev *dc);
 
 __printf(2, 3)
 bool bch_cache_set_error(struct cache_set *, const char *, ...);
@@ -905,6 +953,7 @@ void bch_write_bdev_super(struct cached_dev *, struct closure *);
 
 extern struct workqueue_struct *bcache_wq;
 extern const char * const bch_cache_modes[];
+extern const char * const bch_stop_on_failure_modes[];
 extern struct mutex bch_register_lock;
 extern struct list_head bch_cache_sets;
 
diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index e56d3ecdbfcb..579c696a5fe0 100644
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -1072,7 +1072,7 @@ EXPORT_SYMBOL(bch_btree_iter_init);
 static inline struct bkey *__bch_btree_iter_next(struct btree_iter *iter,
 						 btree_iter_cmp_fn *cmp)
 {
-	struct btree_iter_set unused;
+	struct btree_iter_set b __maybe_unused;
 	struct bkey *ret = NULL;
 
 	if (!btree_iter_end(iter)) {
@@ -1087,7 +1087,7 @@ static inline struct bkey *__bch_btree_iter_next(struct btree_iter *iter,
 		}
 
 		if (iter->data->k == iter->data->end)
-			heap_pop(iter, unused, cmp);
+			heap_pop(iter, b, cmp);
 		else
 			heap_sift(iter, 0, cmp);
 	}
diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h
index fa506c1aa524..0c24280f3b98 100644
--- a/drivers/md/bcache/bset.h
+++ b/drivers/md/bcache/bset.h
@@ -531,14 +531,15 @@ int __bch_keylist_realloc(struct keylist *, unsigned);
 #ifdef CONFIG_BCACHE_DEBUG
 
 int __bch_count_data(struct btree_keys *);
-void __bch_check_keys(struct btree_keys *, const char *, ...);
+void __printf(2, 3) __bch_check_keys(struct btree_keys *, const char *, ...);
 void bch_dump_bset(struct btree_keys *, struct bset *, unsigned);
 void bch_dump_bucket(struct btree_keys *);
 
 #else
 
 static inline int __bch_count_data(struct btree_keys *b) { return -1; }
-static inline void __bch_check_keys(struct btree_keys *b, const char *fmt, ...) {}
+static inline void __printf(2, 3)
+	__bch_check_keys(struct btree_keys *b, const char *fmt, ...) {}
 static inline void bch_dump_bucket(struct btree_keys *b) {}
 void bch_dump_bset(struct btree_keys *, struct bset *, unsigned);
 
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index fad9fe8817eb..17936b2dc7d6 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -665,6 +665,7 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
 	struct btree *b, *t;
 	unsigned long i, nr = sc->nr_to_scan;
 	unsigned long freed = 0;
+	unsigned int btree_cache_used;
 
 	if (c->shrinker_disabled)
 		return SHRINK_STOP;
@@ -689,9 +690,10 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
 	nr = min_t(unsigned long, nr, mca_can_free(c));
 
 	i = 0;
+	btree_cache_used = c->btree_cache_used;
 	list_for_each_entry_safe(b, t, &c->btree_cache_freeable, list) {
-		if (freed >= nr)
-			break;
+		if (nr <= 0)
+			goto out;
 
 		if (++i > 3 &&
 		    !mca_reap(b, 0, false)) {
@@ -699,9 +701,10 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
 			rw_unlock(true, b);
 			freed++;
 		}
+		nr--;
 	}
 
-	for (i = 0; (nr--) && i < c->btree_cache_used; i++) {
+	for (;  (nr--) && i < btree_cache_used; i++) {
 		if (list_empty(&c->btree_cache))
 			goto out;
 
@@ -719,7 +722,7 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
 	}
 out:
 	mutex_unlock(&c->bucket_lock);
-	return freed;
+	return freed * c->btree_pages;
 }
 
 static unsigned long bch_mca_count(struct shrinker *shrink,
@@ -959,7 +962,7 @@ err:
 	return b;
 }
 
-/**
+/*
  * bch_btree_node_get - find a btree node in the cache and lock it, reading it
  * in from disk if necessary.
  *
@@ -1744,6 +1747,7 @@ static void bch_btree_gc(struct cache_set *c)
 
 	btree_gc_start(c);
 
+	/* if CACHE_SET_IO_DISABLE set, gc thread should stop too */
 	do {
 		ret = btree_root(gc_root, c, &op, &writes, &stats);
 		closure_sync(&writes);
@@ -1751,7 +1755,7 @@ static void bch_btree_gc(struct cache_set *c)
 
 		if (ret && ret != -EAGAIN)
 			pr_warn("gc failed!");
-	} while (ret);
+	} while (ret && !test_bit(CACHE_SET_IO_DISABLE, &c->flags));
 
 	bch_btree_gc_finish(c);
 	wake_up_allocators(c);
@@ -1789,15 +1793,19 @@ static int bch_gc_thread(void *arg)
 
 	while (1) {
 		wait_event_interruptible(c->gc_wait,
-			   kthread_should_stop() || gc_should_run(c));
+			   kthread_should_stop() ||
+			   test_bit(CACHE_SET_IO_DISABLE, &c->flags) ||
+			   gc_should_run(c));
 
-		if (kthread_should_stop())
+		if (kthread_should_stop() ||
+		    test_bit(CACHE_SET_IO_DISABLE, &c->flags))
 			break;
 
 		set_gc_sectors(c);
 		bch_btree_gc(c);
 	}
 
+	wait_for_kthread_stop();
 	return 0;
 }
 
@@ -2170,7 +2178,7 @@ int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
 
 		if (b->key.ptr[0] != btree_ptr ||
                    b->seq != seq + 1) {
-                       op->lock = b->level;
+			op->lock = b->level;
 			goto out;
                }
 	}
diff --git a/drivers/md/bcache/closure.c b/drivers/md/bcache/closure.c
index 7f12920c14f7..0e14969182c6 100644
--- a/drivers/md/bcache/closure.c
+++ b/drivers/md/bcache/closure.c
@@ -46,7 +46,7 @@ void closure_sub(struct closure *cl, int v)
 }
 EXPORT_SYMBOL(closure_sub);
 
-/**
+/*
  * closure_put - decrement a closure's refcount
  */
 void closure_put(struct closure *cl)
@@ -55,7 +55,7 @@ void closure_put(struct closure *cl)
 }
 EXPORT_SYMBOL(closure_put);
 
-/**
+/*
  * closure_wake_up - wake up all closures on a wait list, without memory barrier
  */
 void __closure_wake_up(struct closure_waitlist *wait_list)
@@ -79,9 +79,9 @@ EXPORT_SYMBOL(__closure_wake_up);
 
 /**
  * closure_wait - add a closure to a waitlist
- *
- * @waitlist will own a ref on @cl, which will be released when
+ * @waitlist: will own a ref on @cl, which will be released when
  * closure_wake_up() is called on @waitlist.
+ * @cl: closure pointer.
  *
  */
 bool closure_wait(struct closure_waitlist *waitlist, struct closure *cl)
@@ -157,7 +157,7 @@ void closure_debug_destroy(struct closure *cl)
 }
 EXPORT_SYMBOL(closure_debug_destroy);
 
-static struct dentry *debug;
+static struct dentry *closure_debug;
 
 static int debug_seq_show(struct seq_file *f, void *data)
 {
@@ -199,11 +199,12 @@ static const struct file_operations debug_ops = {
 	.release	= single_release
 };
 
-void __init closure_debug_init(void)
+int __init closure_debug_init(void)
 {
-	debug = debugfs_create_file("closures", 0400, NULL, NULL, &debug_ops);
+	closure_debug = debugfs_create_file("closures",
+				0400, bcache_debug, NULL, &debug_ops);
+	return IS_ERR_OR_NULL(closure_debug);
 }
-
 #endif
 
 MODULE_AUTHOR("Kent Overstreet <koverstreet@google.com>");
diff --git a/drivers/md/bcache/closure.h b/drivers/md/bcache/closure.h
index 3b9dfc9962ad..71427eb5fdae 100644
--- a/drivers/md/bcache/closure.h
+++ b/drivers/md/bcache/closure.h
@@ -105,6 +105,7 @@
 struct closure;
 struct closure_syncer;
 typedef void (closure_fn) (struct closure *);
+extern struct dentry *bcache_debug;
 
 struct closure_waitlist {
 	struct llist_head	list;
@@ -185,13 +186,13 @@ static inline void closure_sync(struct closure *cl)
 
 #ifdef CONFIG_BCACHE_CLOSURES_DEBUG
 
-void closure_debug_init(void);
+int closure_debug_init(void);
 void closure_debug_create(struct closure *cl);
 void closure_debug_destroy(struct closure *cl);
 
 #else
 
-static inline void closure_debug_init(void) {}
+static inline int closure_debug_init(void) { return 0; }
 static inline void closure_debug_create(struct closure *cl) {}
 static inline void closure_debug_destroy(struct closure *cl) {}
 
diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index af89408befe8..028f7b386e01 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c
@@ -17,7 +17,7 @@
 #include <linux/random.h>
 #include <linux/seq_file.h>
 
-static struct dentry *debug;
+struct dentry *bcache_debug;
 
 #ifdef CONFIG_BCACHE_DEBUG
 
@@ -232,11 +232,11 @@ static const struct file_operations cache_set_debug_ops = {
 
 void bch_debug_init_cache_set(struct cache_set *c)
 {
-	if (!IS_ERR_OR_NULL(debug)) {
+	if (!IS_ERR_OR_NULL(bcache_debug)) {
 		char name[50];
 		snprintf(name, 50, "bcache-%pU", c->sb.set_uuid);
 
-		c->debug = debugfs_create_file(name, 0400, debug, c,
+		c->debug = debugfs_create_file(name, 0400, bcache_debug, c,
 					       &cache_set_debug_ops);
 	}
 }
@@ -245,13 +245,13 @@ void bch_debug_init_cache_set(struct cache_set *c)
 
 void bch_debug_exit(void)
 {
-	if (!IS_ERR_OR_NULL(debug))
-		debugfs_remove_recursive(debug);
+	if (!IS_ERR_OR_NULL(bcache_debug))
+		debugfs_remove_recursive(bcache_debug);
 }
 
 int __init bch_debug_init(struct kobject *kobj)
 {
-	debug = debugfs_create_dir("bcache", NULL);
+	bcache_debug = debugfs_create_dir("bcache", NULL);
 
-	return IS_ERR_OR_NULL(debug);
+	return IS_ERR_OR_NULL(bcache_debug);
 }
diff --git a/drivers/md/bcache/extents.c b/drivers/md/bcache/extents.c
index f9d391711595..c334e6666461 100644
--- a/drivers/md/bcache/extents.c
+++ b/drivers/md/bcache/extents.c
@@ -534,7 +534,6 @@ err:
 static bool bch_extent_bad(struct btree_keys *bk, const struct bkey *k)
 {
 	struct btree *b = container_of(bk, struct btree, keys);
-	struct bucket *g;
 	unsigned i, stale;
 
 	if (!KEY_PTRS(k) ||
@@ -549,7 +548,6 @@ static bool bch_extent_bad(struct btree_keys *bk, const struct bkey *k)
 		return false;
 
 	for (i = 0; i < KEY_PTRS(k); i++) {
-		g = PTR_BUCKET(b->c, k, i);
 		stale = ptr_stale(b->c, k, i);
 
 		btree_bug_on(stale > 96, b,
diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c
index a783c5a41ff1..7fac97ae036e 100644
--- a/drivers/md/bcache/io.c
+++ b/drivers/md/bcache/io.c
@@ -38,7 +38,7 @@ void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
 	bio_set_dev(bio, PTR_CACHE(c, &b->key, 0)->bdev);
 
 	b->submit_time_us = local_clock_us();
-	closure_bio_submit(bio, bio->bi_private);
+	closure_bio_submit(c, bio, bio->bi_private);
 }
 
 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
@@ -50,6 +50,20 @@ void bch_submit_bbio(struct bio *bio, struct cache_set *c,
 }
 
 /* IO errors */
+void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
+{
+	char buf[BDEVNAME_SIZE];
+	unsigned errors;
+
+	WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
+
+	errors = atomic_add_return(1, &dc->io_errors);
+	if (errors < dc->error_limit)
+		pr_err("%s: IO error on backing device, unrecoverable",
+			bio_devname(bio, buf));
+	else
+		bch_cached_dev_error(dc);
+}
 
 void bch_count_io_errors(struct cache *ca,
 			 blk_status_t error,
diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 1b736b860739..18f1b5239620 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -62,7 +62,7 @@ reread:		left = ca->sb.bucket_size - offset;
 		bio_set_op_attrs(bio, REQ_OP_READ, 0);
 		bch_bio_map(bio, data);
 
-		closure_bio_submit(bio, &cl);
+		closure_bio_submit(ca->set, bio, &cl);
 		closure_sync(&cl);
 
 		/* This function could be simpler now since we no longer write
@@ -493,7 +493,7 @@ static void journal_reclaim(struct cache_set *c)
 	struct cache *ca;
 	uint64_t last_seq;
 	unsigned iter, n = 0;
-	atomic_t p;
+	atomic_t p __maybe_unused;
 
 	atomic_long_inc(&c->reclaim);
 
@@ -594,6 +594,7 @@ static void journal_write_done(struct closure *cl)
 }
 
 static void journal_write_unlock(struct closure *cl)
+	__releases(&c->journal.lock)
 {
 	struct cache_set *c = container_of(cl, struct cache_set, journal.io);
 
@@ -674,7 +675,7 @@ static void journal_write_unlocked(struct closure *cl)
 	spin_unlock(&c->journal.lock);
 
 	while ((bio = bio_list_pop(&list)))
-		closure_bio_submit(bio, cl);
+		closure_bio_submit(c, bio, cl);
 
 	continue_at(cl, journal_write_done, NULL);
 }
@@ -705,6 +706,7 @@ static void journal_try_write(struct cache_set *c)
 
 static struct journal_write *journal_wait_for_write(struct cache_set *c,
 						    unsigned nkeys)
+	__acquires(&c->journal.lock)
 {
 	size_t sectors;
 	struct closure cl;
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 6422846b546e..a65e3365eeb9 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -139,6 +139,7 @@ static void bch_data_invalidate(struct closure *cl)
 	}
 
 	op->insert_data_done = true;
+	/* get in bch_data_insert() */
 	bio_put(bio);
 out:
 	continue_at(cl, bch_data_insert_keys, op->wq);
@@ -295,6 +296,7 @@ err:
 
 /**
  * bch_data_insert - stick some data in the cache
+ * @cl: closure pointer.
  *
  * This is the starting point for any data to end up in a cache device; it could
  * be from a normal write, or a writeback write, or a write to a flash only
@@ -630,6 +632,41 @@ static void request_endio(struct bio *bio)
 	closure_put(cl);
 }
 
+static void backing_request_endio(struct bio *bio)
+{
+	struct closure *cl = bio->bi_private;
+
+	if (bio->bi_status) {
+		struct search *s = container_of(cl, struct search, cl);
+		struct cached_dev *dc = container_of(s->d,
+						     struct cached_dev, disk);
+		/*
+		 * If a bio has REQ_PREFLUSH for writeback mode, it is
+		 * speically assembled in cached_dev_write() for a non-zero
+		 * write request which has REQ_PREFLUSH. we don't set
+		 * s->iop.status by this failure, the status will be decided
+		 * by result of bch_data_insert() operation.
+		 */
+		if (unlikely(s->iop.writeback &&
+			     bio->bi_opf & REQ_PREFLUSH)) {
+			char buf[BDEVNAME_SIZE];
+
+			bio_devname(bio, buf);
+			pr_err("Can't flush %s: returned bi_status %i",
+				buf, bio->bi_status);
+		} else {
+			/* set to orig_bio->bi_status in bio_complete() */
+			s->iop.status = bio->bi_status;
+		}
+		s->recoverable = false;
+		/* should count I/O error for backing device here */
+		bch_count_backing_io_errors(dc, bio);
+	}
+
+	bio_put(bio);
+	closure_put(cl);
+}
+
 static void bio_complete(struct search *s)
 {
 	if (s->orig_bio) {
@@ -644,13 +681,21 @@ static void bio_complete(struct search *s)
 	}
 }
 
-static void do_bio_hook(struct search *s, struct bio *orig_bio)
+static void do_bio_hook(struct search *s,
+			struct bio *orig_bio,
+			bio_end_io_t *end_io_fn)
 {
 	struct bio *bio = &s->bio.bio;
 
 	bio_init(bio, NULL, 0);
 	__bio_clone_fast(bio, orig_bio);
-	bio->bi_end_io		= request_endio;
+	/*
+	 * bi_end_io can be set separately somewhere else, e.g. the
+	 * variants in,
+	 * - cache_bio->bi_end_io from cached_dev_cache_miss()
+	 * - n->bi_end_io from cache_lookup_fn()
+	 */
+	bio->bi_end_io		= end_io_fn;
 	bio->bi_private		= &s->cl;
 
 	bio_cnt_set(bio, 3);
@@ -676,7 +721,7 @@ static inline struct search *search_alloc(struct bio *bio,
 	s = mempool_alloc(d->c->search, GFP_NOIO);
 
 	closure_init(&s->cl, NULL);
-	do_bio_hook(s, bio);
+	do_bio_hook(s, bio, request_endio);
 
 	s->orig_bio		= bio;
 	s->cache_miss		= NULL;
@@ -743,11 +788,12 @@ static void cached_dev_read_error(struct closure *cl)
 		trace_bcache_read_retry(s->orig_bio);
 
 		s->iop.status = 0;
-		do_bio_hook(s, s->orig_bio);
+		do_bio_hook(s, s->orig_bio, backing_request_endio);
 
 		/* XXX: invalidate cache */
 
-		closure_bio_submit(bio, cl);
+		/* I/O request sent to backing device */
+		closure_bio_submit(s->iop.c, bio, cl);
 	}
 
 	continue_at(cl, cached_dev_cache_miss_done, NULL);
@@ -859,7 +905,7 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
 	bio_copy_dev(cache_bio, miss);
 	cache_bio->bi_iter.bi_size	= s->insert_bio_sectors << 9;
 
-	cache_bio->bi_end_io	= request_endio;
+	cache_bio->bi_end_io	= backing_request_endio;
 	cache_bio->bi_private	= &s->cl;
 
 	bch_bio_map(cache_bio, NULL);
@@ -872,15 +918,17 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
 	s->cache_miss	= miss;
 	s->iop.bio	= cache_bio;
 	bio_get(cache_bio);
-	closure_bio_submit(cache_bio, &s->cl);
+	/* I/O request sent to backing device */
+	closure_bio_submit(s->iop.c, cache_bio, &s->cl);
 
 	return ret;
 out_put:
 	bio_put(cache_bio);
 out_submit:
-	miss->bi_end_io		= request_endio;
+	miss->bi_end_io		= backing_request_endio;
 	miss->bi_private	= &s->cl;
-	closure_bio_submit(miss, &s->cl);
+	/* I/O request sent to backing device */
+	closure_bio_submit(s->iop.c, miss, &s->cl);
 	return ret;
 }
 
@@ -943,31 +991,46 @@ static void cached_dev_write(struct cached_dev *dc, struct search *s)
 		s->iop.bio = s->orig_bio;
 		bio_get(s->iop.bio);
 
-		if ((bio_op(bio) != REQ_OP_DISCARD) ||
-		    blk_queue_discard(bdev_get_queue(dc->bdev)))
-			closure_bio_submit(bio, cl);
+		if (bio_op(bio) == REQ_OP_DISCARD &&
+		    !blk_queue_discard(bdev_get_queue(dc->bdev)))
+			goto insert_data;
+
+		/* I/O request sent to backing device */
+		bio->bi_end_io = backing_request_endio;
+		closure_bio_submit(s->iop.c, bio, cl);
+
 	} else if (s->iop.writeback) {
 		bch_writeback_add(dc);
 		s->iop.bio = bio;
 
 		if (bio->bi_opf & REQ_PREFLUSH) {
-			/* Also need to send a flush to the backing device */
-			struct bio *flush = bio_alloc_bioset(GFP_NOIO, 0,
-							     dc->disk.bio_split);
-
+			/*
+			 * Also need to send a flush to the backing
+			 * device.
+			 */
+			struct bio *flush;
+
+			flush = bio_alloc_bioset(GFP_NOIO, 0,
+						 dc->disk.bio_split);
+			if (!flush) {
+				s->iop.status = BLK_STS_RESOURCE;
+				goto insert_data;
+			}
 			bio_copy_dev(flush, bio);
-			flush->bi_end_io = request_endio;
+			flush->bi_end_io = backing_request_endio;
 			flush->bi_private = cl;
 			flush->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
-
-			closure_bio_submit(flush, cl);
+			/* I/O request sent to backing device */
+			closure_bio_submit(s->iop.c, flush, cl);
 		}
 	} else {
 		s->iop.bio = bio_clone_fast(bio, GFP_NOIO, dc->disk.bio_split);
-
-		closure_bio_submit(bio, cl);
+		/* I/O request sent to backing device */
+		bio->bi_end_io = backing_request_endio;
+		closure_bio_submit(s->iop.c, bio, cl);
 	}
 
+insert_data:
 	closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
 	continue_at(cl, cached_dev_write_complete, NULL);
 }
@@ -981,11 +1044,67 @@ static void cached_dev_nodata(struct closure *cl)
 		bch_journal_meta(s->iop.c, cl);
 
 	/* If it's a flush, we send the flush to the backing device too */
-	closure_bio_submit(bio, cl);
+	bio->bi_end_io = backing_request_endio;
+	closure_bio_submit(s->iop.c, bio, cl);
 
 	continue_at(cl, cached_dev_bio_complete, NULL);
 }
 
+struct detached_dev_io_private {
+	struct bcache_device	*d;
+	unsigned long		start_time;
+	bio_end_io_t		*bi_end_io;
+	void			*bi_private;
+};
+
+static void detached_dev_end_io(struct bio *bio)
+{
+	struct detached_dev_io_private *ddip;
+
+	ddip = bio->bi_private;
+	bio->bi_end_io = ddip->bi_end_io;
+	bio->bi_private = ddip->bi_private;
+
+	generic_end_io_acct(ddip->d->disk->queue,
+			    bio_data_dir(bio),
+			    &ddip->d->disk->part0, ddip->start_time);
+
+	if (bio->bi_status) {
+		struct cached_dev *dc = container_of(ddip->d,
+						     struct cached_dev, disk);
+		/* should count I/O error for backing device here */
+		bch_count_backing_io_errors(dc, bio);
+	}
+
+	kfree(ddip);
+	bio->bi_end_io(bio);
+}
+
+static void detached_dev_do_request(struct bcache_device *d, struct bio *bio)
+{
+	struct detached_dev_io_private *ddip;
+	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+
+	/*
+	 * no need to call closure_get(&dc->disk.cl),
+	 * because upper layer had already opened bcache device,
+	 * which would call closure_get(&dc->disk.cl)
+	 */
+	ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO);
+	ddip->d = d;
+	ddip->start_time = jiffies;
+	ddip->bi_end_io = bio->bi_end_io;
+	ddip->bi_private = bio->bi_private;
+	bio->bi_end_io = detached_dev_end_io;
+	bio->bi_private = ddip;
+
+	if ((bio_op(bio) == REQ_OP_DISCARD) &&
+	    !blk_queue_discard(bdev_get_queue(dc->bdev)))
+		bio->bi_end_io(bio);
+	else
+		generic_make_request(bio);
+}
+
 /* Cached devices - read & write stuff */
 
 static blk_qc_t cached_dev_make_request(struct request_queue *q,
@@ -996,6 +1115,13 @@ static blk_qc_t cached_dev_make_request(struct request_queue *q,
 	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
 	int rw = bio_data_dir(bio);
 
+	if (unlikely((d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags)) ||
+		     dc->io_disable)) {
+		bio->bi_status = BLK_STS_IOERR;
+		bio_endio(bio);
+		return BLK_QC_T_NONE;
+	}
+
 	atomic_set(&dc->backing_idle, 0);
 	generic_start_io_acct(q, rw, bio_sectors(bio), &d->disk->part0);
 
@@ -1022,13 +1148,9 @@ static blk_qc_t cached_dev_make_request(struct request_queue *q,
 			else
 				cached_dev_read(dc, s);
 		}
-	} else {
-		if ((bio_op(bio) == REQ_OP_DISCARD) &&
-		    !blk_queue_discard(bdev_get_queue(dc->bdev)))
-			bio_endio(bio);
-		else
-			generic_make_request(bio);
-	}
+	} else
+		/* I/O request sent to backing device */
+		detached_dev_do_request(d, bio);
 
 	return BLK_QC_T_NONE;
 }
@@ -1112,6 +1234,12 @@ static blk_qc_t flash_dev_make_request(struct request_queue *q,
 	struct bcache_device *d = bio->bi_disk->private_data;
 	int rw = bio_data_dir(bio);
 
+	if (unlikely(d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags))) {
+		bio->bi_status = BLK_STS_IOERR;
+		bio_endio(bio);
+		return BLK_QC_T_NONE;
+	}
+
 	generic_start_io_acct(q, rw, bio_sectors(bio), &d->disk->part0);
 
 	s = search_alloc(bio, d);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index f2273143b3cb..d90d9e59ca00 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -47,6 +47,14 @@ const char * const bch_cache_modes[] = {
 	NULL
 };
 
+/* Default is -1; we skip past it for stop_when_cache_s