Resguardo inicial

linux-7.2.3/drivers/md/bcache/Kconfig

@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config BCACHE
+	tristate "Block device as cache"
+	select BLOCK_HOLDER_DEPRECATED if SYSFS
+	select CRC64
+	select CLOSURES
+	help
+	Allows a block device to be used as cache for other devices; uses
+	a btree for indexing and the layout is optimized for SSDs.
+
+	See Documentation/admin-guide/bcache.rst for details.
+
+config BCACHE_DEBUG
+	bool "Bcache debugging"
+	depends on BCACHE
+	help
+	Don't select this option unless you're a developer
+
+	Enables extra debugging tools, allows expensive runtime checks to be
+	turned on.
+
+config BCACHE_ASYNC_REGISTRATION
+	bool "Asynchronous device registration"
+	depends on BCACHE
+	help
+	Add a sysfs file /sys/fs/bcache/register_async. Writing registering
+	device path into this file will returns immediately and the real
+	registration work is handled in kernel work queue in asynchronous
+	way.

linux-7.2.3/drivers/md/bcache/Makefile

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_BCACHE)	+= bcache.o
+
+bcache-y		:= alloc.o bset.o btree.o debug.o extents.o io.o\
+	journal.o movinggc.o request.o stats.o super.o sysfs.o trace.o\
+	util.o writeback.o features.o

linux-7.2.3/drivers/md/bcache/alloc.c

@@ -0,0 +1,720 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Primary bucket allocation code
+ *
+ * Copyright 2012 Google, Inc.
+ *
+ * Allocation in bcache is done in terms of buckets:
+ *
+ * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in
+ * btree pointers - they must match for the pointer to be considered valid.
+ *
+ * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a
+ * bucket simply by incrementing its gen.
+ *
+ * The gens (along with the priorities; it's really the gens are important but
+ * the code is named as if it's the priorities) are written in an arbitrary list
+ * of buckets on disk, with a pointer to them in the journal header.
+ *
+ * When we invalidate a bucket, we have to write its new gen to disk and wait
+ * for that write to complete before we use it - otherwise after a crash we
+ * could have pointers that appeared to be good but pointed to data that had
+ * been overwritten.
+ *
+ * Since the gens and priorities are all stored contiguously on disk, we can
+ * batch this up: We fill up the free_inc list with freshly invalidated buckets,
+ * call prio_write(), and when prio_write() finishes we pull buckets off the
+ * free_inc list.
+ *
+ * free_inc isn't the only freelist - if it was, we'd often to sleep while
+ * priorities and gens were being written before we could allocate. c->free is a
+ * smaller freelist, and buckets on that list are always ready to be used.
+ *
+ * There is another freelist, because sometimes we have buckets that we know
+ * have nothing pointing into them - these we can reuse without waiting for
+ * priorities to be rewritten. These come from freed btree nodes and buckets
+ * that garbage collection discovered no longer had valid keys pointing into
+ * them (because they were overwritten). That's the unused list - buckets on the
+ * unused list move to the free list.
+ *
+ * It's also important to ensure that gens don't wrap around - with respect to
+ * either the oldest gen in the btree or the gen on disk. This is quite
+ * difficult to do in practice, but we explicitly guard against it anyways - if
+ * a bucket is in danger of wrapping around we simply skip invalidating it that
+ * time around, and we garbage collect or rewrite the priorities sooner than we
+ * would have otherwise.
+ *
+ * bch_bucket_alloc() allocates a single bucket from a specific cache.
+ *
+ * bch_bucket_alloc_set() allocates one  bucket from different caches
+ * out of a cache set.
+ *
+ * free_some_buckets() drives all the processes described above. It's called
+ * from bch_bucket_alloc() and a few other places that need to make sure free
+ * buckets are ready.
+ *
+ * invalidate_buckets_(lru|fifo)() find buckets that are available to be
+ * invalidated, and then invalidate them and stick them on the free_inc list -
+ * in either lru or fifo order.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+
+#include <linux/blkdev.h>
+#include <linux/kthread.h>
+#include <linux/random.h>
+#include <trace/events/bcache.h>
+
+#define MAX_OPEN_BUCKETS 128
+
+/* Bucket heap / gen */
+
+uint8_t bch_inc_gen(struct cache *ca, struct bucket *b)
+{
+	uint8_t ret = ++b->gen;
+
+	ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b));
+	WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX);
+
+	return ret;
+}
+
+void bch_rescale_priorities(struct cache_set *c, int sectors)
+{
+	struct cache *ca;
+	struct bucket *b;
+	unsigned long next = c->nbuckets * c->cache->sb.bucket_size / 1024;
+	int r;
+
+	atomic_sub(sectors, &c->rescale);
+
+	do {
+		r = atomic_read(&c->rescale);
+
+		if (r >= 0)
+			return;
+	} while (atomic_cmpxchg(&c->rescale, r, r + next) != r);
+
+	mutex_lock(&c->bucket_lock);
+
+	c->min_prio = USHRT_MAX;
+
+	ca = c->cache;
+	for_each_bucket(b, ca)
+		if (b->prio &&
+		    b->prio != BTREE_PRIO &&
+		    !atomic_read(&b->pin)) {
+			b->prio--;
+			c->min_prio = min(c->min_prio, b->prio);
+		}
+
+	mutex_unlock(&c->bucket_lock);
+}
+
+/*
+ * Background allocation thread: scans for buckets to be invalidated,
+ * invalidates them, rewrites prios/gens (marking them as invalidated on disk),
+ * then puts them on the various freelists.
+ */
+
+static inline bool can_inc_bucket_gen(struct bucket *b)
+{
+	return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX;
+}
+
+bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b)
+{
+	return (ca->set->gc_mark_valid || b->reclaimable_in_gc) &&
+	       ((!GC_MARK(b) || GC_MARK(b) == GC_MARK_RECLAIMABLE) &&
+	       !atomic_read(&b->pin) && can_inc_bucket_gen(b));
+}
+
+void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b)
+{
+	lockdep_assert_held(&ca->set->bucket_lock);
+	BUG_ON(GC_MARK(b) && GC_MARK(b) != GC_MARK_RECLAIMABLE);
+
+	if (GC_SECTORS_USED(b))
+		trace_bcache_invalidate(ca, b - ca->buckets);
+
+	bch_inc_gen(ca, b);
+	b->prio = INITIAL_PRIO;
+	atomic_inc(&b->pin);
+	b->reclaimable_in_gc = 0;
+}
+
+static void bch_invalidate_one_bucket(struct cache *ca, struct bucket *b)
+{
+	__bch_invalidate_one_bucket(ca, b);
+
+	fifo_push(&ca->free_inc, b - ca->buckets);
+}
+
+/*
+ * Determines what order we're going to reuse buckets, smallest bucket_prio()
+ * first: we also take into account the number of sectors of live data in that
+ * bucket, and in order for that multiply to make sense we have to scale bucket
+ *
+ * Thus, we scale the bucket priorities so that the bucket with the smallest
+ * prio is worth 1/8th of what INITIAL_PRIO is worth.
+ */
+
+#define bucket_prio(b)							\
+({									\
+	unsigned int min_prio = (INITIAL_PRIO - ca->set->min_prio) / 8;	\
+									\
+	(b->prio - ca->set->min_prio + min_prio) * GC_SECTORS_USED(b);	\
+})
+
+#define bucket_max_cmp(l, r)	(bucket_prio(l) < bucket_prio(r))
+#define bucket_min_cmp(l, r)	(bucket_prio(l) > bucket_prio(r))
+
+static void invalidate_buckets_lru(struct cache *ca)
+{
+	struct bucket *b;
+	ssize_t i;
+
+	ca->heap.used = 0;
+
+	for_each_bucket(b, ca) {
+		if (!bch_can_invalidate_bucket(ca, b))
+			continue;
+
+		if (!heap_full(&ca->heap))
+			heap_add(&ca->heap, b, bucket_max_cmp);
+		else if (bucket_max_cmp(b, heap_peek(&ca->heap))) {
+			ca->heap.data[0] = b;
+			heap_sift(&ca->heap, 0, bucket_max_cmp);
+		}
+	}
+
+	for (i = ca->heap.used / 2 - 1; i >= 0; --i)
+		heap_sift(&ca->heap, i, bucket_min_cmp);
+
+	while (!fifo_full(&ca->free_inc)) {
+		if (!heap_pop(&ca->heap, b, bucket_min_cmp)) {
+			/*
+			 * We don't want to be calling invalidate_buckets()
+			 * multiple times when it can't do anything
+			 */
+			ca->invalidate_needs_gc = 1;
+			wake_up_gc(ca->set);
+			return;
+		}
+
+		bch_invalidate_one_bucket(ca, b);
+	}
+}
+
+static void invalidate_buckets_fifo(struct cache *ca)
+{
+	struct bucket *b;
+	size_t checked = 0;
+
+	while (!fifo_full(&ca->free_inc)) {
+		if (ca->fifo_last_bucket <  ca->sb.first_bucket ||
+		    ca->fifo_last_bucket >= ca->sb.nbuckets)
+			ca->fifo_last_bucket = ca->sb.first_bucket;
+
+		b = ca->buckets + ca->fifo_last_bucket++;
+
+		if (bch_can_invalidate_bucket(ca, b))
+			bch_invalidate_one_bucket(ca, b);
+
+		if (++checked >= ca->sb.nbuckets) {
+			ca->invalidate_needs_gc = 1;
+			wake_up_gc(ca->set);
+			return;
+		}
+	}
+}
+
+static void invalidate_buckets_random(struct cache *ca)
+{
+	struct bucket *b;
+	size_t checked = 0;
+
+	while (!fifo_full(&ca->free_inc)) {
+		size_t n;
+
+		get_random_bytes(&n, sizeof(n));
+
+		n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket);
+		n += ca->sb.first_bucket;
+
+		b = ca->buckets + n;
+
+		if (bch_can_invalidate_bucket(ca, b))
+			bch_invalidate_one_bucket(ca, b);
+
+		if (++checked >= ca->sb.nbuckets / 2) {
+			ca->invalidate_needs_gc = 1;
+			wake_up_gc(ca->set);
+			return;
+		}
+	}
+}
+
+static void invalidate_buckets(struct cache *ca)
+{
+	BUG_ON(ca->invalidate_needs_gc);
+
+	switch (CACHE_REPLACEMENT(&ca->sb)) {
+	case CACHE_REPLACEMENT_LRU:
+		invalidate_buckets_lru(ca);
+		break;
+	case CACHE_REPLACEMENT_FIFO:
+		invalidate_buckets_fifo(ca);
+		break;
+	case CACHE_REPLACEMENT_RANDOM:
+		invalidate_buckets_random(ca);
+		break;
+	}
+}
+
+#define allocator_wait(ca, cond)					\
+do {									\
+	while (1) {							\
+		set_current_state(TASK_INTERRUPTIBLE);			\
+		if (cond)						\
+			break;						\
+									\
+		mutex_unlock(&(ca)->set->bucket_lock);			\
+		if (kthread_should_stop() ||				\
+		    test_bit(CACHE_SET_IO_DISABLE, &ca->set->flags)) {	\
+			set_current_state(TASK_RUNNING);		\
+			goto out;					\
+		}							\
+									\
+		schedule();						\
+		mutex_lock(&(ca)->set->bucket_lock);			\
+	}								\
+	__set_current_state(TASK_RUNNING);				\
+} while (0)
+
+static int bch_allocator_push(struct cache *ca, long bucket)
+{
+	unsigned int i;
+
+	/* Prios/gens are actually the most important reserve */
+	if (fifo_push(&ca->free[RESERVE_PRIO], bucket))
+		return true;
+
+	for (i = 0; i < RESERVE_NR; i++)
+		if (fifo_push(&ca->free[i], bucket))
+			return true;
+
+	return false;
+}
+
+static int bch_allocator_thread(void *arg)
+{
+	struct cache *ca = arg;
+
+	mutex_lock(&ca->set->bucket_lock);
+
+	while (1) {
+		/*
+		 * First, we pull buckets off of the unused and free_inc lists,
+		 * then we add the bucket to the free list:
+		 */
+		while (1) {
+			long bucket;
+
+			if (!fifo_pop(&ca->free_inc, bucket))
+				break;
+
+			allocator_wait(ca, bch_allocator_push(ca, bucket));
+			wake_up(&ca->set->btree_cache_wait);
+			wake_up(&ca->set->bucket_wait);
+		}
+
+		/*
+		 * We've run out of free buckets, we need to find some buckets
+		 * we can invalidate. First, invalidate them in memory and add
+		 * them to the free_inc list:
+		 */
+
+retry_invalidate:
+		allocator_wait(ca, !ca->invalidate_needs_gc);
+		invalidate_buckets(ca);
+
+		/*
+		 * Now, we write their new gens to disk so we can start writing
+		 * new stuff to them:
+		 */
+		allocator_wait(ca, !atomic_read(&ca->set->prio_blocked));
+		if (CACHE_SYNC(&ca->sb)) {
+			/*
+			 * This could deadlock if an allocation with a btree
+			 * node locked ever blocked - having the btree node
+			 * locked would block garbage collection, but here we're
+			 * waiting on garbage collection before we invalidate
+			 * and free anything.
+			 *
+			 * But this should be safe since the btree code always
+			 * uses btree_check_reserve() before allocating now, and
+			 * if it fails it blocks without btree nodes locked.
+			 */
+			if (!fifo_full(&ca->free_inc))
+				goto retry_invalidate;
+
+			if (bch_prio_write(ca, false) < 0) {
+				ca->invalidate_needs_gc = 1;
+				wake_up_gc(ca->set);
+			}
+		}
+	}
+out:
+	wait_for_kthread_stop();
+	return 0;
+}
+
+/* Allocation */
+
+long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait)
+{
+	DEFINE_WAIT(w);
+	struct bucket *b;
+	long r;
+
+
+	/* No allocation if CACHE_SET_IO_DISABLE bit is set */
+	if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &ca->set->flags)))
+		return -1;
+
+	/* fastpath */
+	if (fifo_pop(&ca->free[RESERVE_NONE], r) ||
+	    fifo_pop(&ca->free[reserve], r))
+		goto out;
+
+	if (!wait) {
+		trace_bcache_alloc_fail(ca, reserve);
+		return -1;
+	}
+
+	do {
+		prepare_to_wait(&ca->set->bucket_wait, &w,
+				TASK_UNINTERRUPTIBLE);
+
+		mutex_unlock(&ca->set->bucket_lock);
+
+		atomic_inc(&ca->set->bucket_wait_cnt);
+		schedule();
+		atomic_dec(&ca->set->bucket_wait_cnt);
+
+		mutex_lock(&ca->set->bucket_lock);
+	} while (!fifo_pop(&ca->free[RESERVE_NONE], r) &&
+		 !fifo_pop(&ca->free[reserve], r));
+
+	finish_wait(&ca->set->bucket_wait, &w);
+out:
+	if (ca->alloc_thread)
+		wake_up_process(ca->alloc_thread);
+
+	trace_bcache_alloc(ca, reserve);
+
+	if (expensive_debug_checks(ca->set)) {
+		size_t iter;
+		long i;
+		unsigned int j;
+
+		for (iter = 0; iter < prio_buckets(ca) * 2; iter++)
+			BUG_ON(ca->prio_buckets[iter] == (uint64_t) r);
+
+		for (j = 0; j < RESERVE_NR; j++)
+			fifo_for_each(i, &ca->free[j], iter)
+				BUG_ON(i == r);
+		fifo_for_each(i, &ca->free_inc, iter)
+			BUG_ON(i == r);
+	}
+
+	b = ca->buckets + r;
+
+	BUG_ON(atomic_read(&b->pin) != 1);
+
+	SET_GC_SECTORS_USED(b, ca->sb.bucket_size);
+
+	if (reserve <= RESERVE_PRIO) {
+		SET_GC_MARK(b, GC_MARK_METADATA);
+		SET_GC_MOVE(b, 0);
+		b->prio = BTREE_PRIO;
+	} else {
+		SET_GC_MARK(b, GC_MARK_RECLAIMABLE);
+		SET_GC_MOVE(b, 0);
+		b->prio = INITIAL_PRIO;
+	}
+
+	if (ca->set->avail_nbuckets > 0) {
+		ca->set->avail_nbuckets--;
+		bch_update_bucket_in_use(ca->set, &ca->set->gc_stats);
+	}
+
+	return r;
+}
+
+void __bch_bucket_free(struct cache *ca, struct bucket *b)
+{
+	SET_GC_MARK(b, 0);
+	SET_GC_SECTORS_USED(b, 0);
+
+	if (ca->set->avail_nbuckets < ca->set->nbuckets) {
+		ca->set->avail_nbuckets++;
+		bch_update_bucket_in_use(ca->set, &ca->set->gc_stats);
+	}
+}
+
+void bch_bucket_free(struct cache_set *c, struct bkey *k)
+{
+	unsigned int i;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		__bch_bucket_free(c->cache, PTR_BUCKET(c, k, i));
+}
+
+int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
+			   struct bkey *k, bool wait)
+{
+	struct cache *ca;
+	long b;
+
+	/* No allocation if CACHE_SET_IO_DISABLE bit is set */
+	if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags)))
+		return -1;
+
+	lockdep_assert_held(&c->bucket_lock);
+
+	bkey_init(k);
+
+	ca = c->cache;
+	b = bch_bucket_alloc(ca, reserve, wait);
+	if (b < 0)
+		return -1;
+
+	k->ptr[0] = MAKE_PTR(ca->buckets[b].gen,
+			     bucket_to_sector(c, b),
+			     ca->sb.nr_this_dev);
+
+	SET_KEY_PTRS(k, 1);
+
+	return 0;
+}
+
+int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
+			 struct bkey *k, bool wait)
+{
+	int ret;
+
+	mutex_lock(&c->bucket_lock);
+	ret = __bch_bucket_alloc_set(c, reserve, k, wait);
+	mutex_unlock(&c->bucket_lock);
+	return ret;
+}
+
+/* Sector allocator */
+
+struct open_bucket {
+	struct list_head	list;
+	unsigned int		last_write_point;
+	unsigned int		sectors_free;
+	BKEY_PADDED(key);
+};
+
+/*
+ * We keep multiple buckets open for writes, and try to segregate different
+ * write streams for better cache utilization: first we try to segregate flash
+ * only volume write streams from cached devices, secondly we look for a bucket
+ * where the last write to it was sequential with the current write, and
+ * failing that we look for a bucket that was last used by the same task.
+ *
+ * The ideas is if you've got multiple tasks pulling data into the cache at the
+ * same time, you'll get better cache utilization if you try to segregate their
+ * data and preserve locality.
+ *
+ * For example, dirty sectors of flash only volume is not reclaimable, if their
+ * dirty sectors mixed with dirty sectors of cached device, such buckets will
+ * be marked as dirty and won't be reclaimed, though the dirty data of cached
+ * device have been written back to backend device.
+ *
+ * And say you've starting Firefox at the same time you're copying a
+ * bunch of files. Firefox will likely end up being fairly hot and stay in the
+ * cache awhile, but the data you copied might not be; if you wrote all that
+ * data to the same buckets it'd get invalidated at the same time.
+ *
+ * Both of those tasks will be doing fairly random IO so we can't rely on
+ * detecting sequential IO to segregate their data, but going off of the task
+ * should be a sane heuristic.
+ */
+static struct open_bucket *pick_data_bucket(struct cache_set *c,
+					    const struct bkey *search,
+					    unsigned int write_point,
+					    struct bkey *alloc)
+{
+	struct open_bucket *ret, *ret_task = NULL;
+
+	list_for_each_entry_reverse(ret, &c->data_buckets, list)
+		if (UUID_FLASH_ONLY(&c->uuids[KEY_INODE(&ret->key)]) !=
+		    UUID_FLASH_ONLY(&c->uuids[KEY_INODE(search)]))
+			continue;
+		else if (!bkey_cmp(&ret->key, search))
+			goto found;
+		else if (ret->last_write_point == write_point)
+			ret_task = ret;
+
+	ret = ret_task ?: list_first_entry(&c->data_buckets,
+					   struct open_bucket, list);
+found:
+	if (!ret->sectors_free && KEY_PTRS(alloc)) {
+		ret->sectors_free = c->cache->sb.bucket_size;
+		bkey_copy(&ret->key, alloc);
+		bkey_init(alloc);
+	}
+
+	if (!ret->sectors_free)
+		ret = NULL;
+
+	return ret;
+}
+
+/*
+ * Allocates some space in the cache to write to, and k to point to the newly
+ * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the
+ * end of the newly allocated space).
+ *
+ * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many
+ * sectors were actually allocated.
+ *
+ * If s->writeback is true, will not fail.
+ */
+bool bch_alloc_sectors(struct cache_set *c,
+		       struct bkey *k,
+		       unsigned int sectors,
+		       unsigned int write_point,
+		       unsigned int write_prio,
+		       bool wait)
+{
+	struct open_bucket *b;
+	BKEY_PADDED(key) alloc;
+	unsigned int i;
+
+	/*
+	 * We might have to allocate a new bucket, which we can't do with a
+	 * spinlock held. So if we have to allocate, we drop the lock, allocate
+	 * and then retry. KEY_PTRS() indicates whether alloc points to
+	 * allocated bucket(s).
+	 */
+
+	bkey_init(&alloc.key);
+	spin_lock(&c->data_bucket_lock);
+
+	while (!(b = pick_data_bucket(c, k, write_point, &alloc.key))) {
+		unsigned int watermark = write_prio
+			? RESERVE_MOVINGGC
+			: RESERVE_NONE;
+
+		spin_unlock(&c->data_bucket_lock);
+
+		if (bch_bucket_alloc_set(c, watermark, &alloc.key, wait))
+			return false;
+
+		spin_lock(&c->data_bucket_lock);
+	}
+
+	/*
+	 * If we had to allocate, we might race and not need to allocate the
+	 * second time we call pick_data_bucket(). If we allocated a bucket but
+	 * didn't use it, drop the refcount bch_bucket_alloc_set() took:
+	 */
+	if (KEY_PTRS(&alloc.key))
+		bkey_put(c, &alloc.key);
+
+	for (i = 0; i < KEY_PTRS(&b->key); i++)
+		EBUG_ON(ptr_stale(c, &b->key, i));
+
+	/* Set up the pointer to the space we're allocating: */
+
+	for (i = 0; i < KEY_PTRS(&b->key); i++)
+		k->ptr[i] = b->key.ptr[i];
+
+	sectors = min(sectors, b->sectors_free);
+
+	SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors);
+	SET_KEY_SIZE(k, sectors);
+	SET_KEY_PTRS(k, KEY_PTRS(&b->key));
+
+	/*
+	 * Move b to the end of the lru, and keep track of what this bucket was
+	 * last used for:
+	 */
+	list_move_tail(&b->list, &c->data_buckets);
+	bkey_copy_key(&b->key, k);
+	b->last_write_point = write_point;
+
+	b->sectors_free	-= sectors;
+
+	for (i = 0; i < KEY_PTRS(&b->key); i++) {
+		SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors);
+
+		atomic_long_add(sectors,
+				&c->cache->sectors_written);
+	}
+
+	if (b->sectors_free < c->cache->sb.block_size)
+		b->sectors_free = 0;
+
+	/*
+	 * k takes refcounts on the buckets it points to until it's inserted
+	 * into the btree, but if we're done with this bucket we just transfer
+	 * get_data_bucket()'s refcount.
+	 */
+	if (b->sectors_free)
+		for (i = 0; i < KEY_PTRS(&b->key); i++)
+			atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin);
+
+	spin_unlock(&c->data_bucket_lock);
+	return true;
+}
+
+/* Init */
+
+void bch_open_buckets_free(struct cache_set *c)
+{
+	struct open_bucket *b;
+
+	while (!list_empty(&c->data_buckets)) {
+		b = list_first_entry(&c->data_buckets,
+				     struct open_bucket, list);
+		list_del(&b->list);
+		kfree(b);
+	}
+}
+
+int bch_open_buckets_alloc(struct cache_set *c)
+{
+	int i;
+
+	spin_lock_init(&c->data_bucket_lock);
+
+	for (i = 0; i < MAX_OPEN_BUCKETS; i++) {
+		struct open_bucket *b = kzalloc_obj(*b);
+
+		if (!b)
+			return -ENOMEM;
+
+		list_add(&b->list, &c->data_buckets);
+	}
+
+	return 0;
+}
+
+int bch_cache_allocator_start(struct cache *ca)
+{
+	struct task_struct *k = kthread_run(bch_allocator_thread,
+					    ca, "bcache_allocator");
+	if (IS_ERR(k))
+		return PTR_ERR(k);
+
+	ca->alloc_thread = k;
+	return 0;
+}

linux-7.2.3/drivers/md/bcache/bcache_ondisk.h

@@ -0,0 +1,446 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _LINUX_BCACHE_H
+#define _LINUX_BCACHE_H
+
+/*
+ * Bcache on disk data structures
+ */
+
+#include <linux/types.h>
+
+#define BITMASK(name, type, field, offset, size)		\
+static inline __u64 name(const type *k)				\
+{ return (k->field >> offset) & ~(~0ULL << size); }		\
+								\
+static inline void SET_##name(type *k, __u64 v)			\
+{								\
+	k->field &= ~(~(~0ULL << size) << offset);		\
+	k->field |= (v & ~(~0ULL << size)) << offset;		\
+}
+
+/* Btree keys - all units are in sectors */
+
+struct bkey {
+	__u64	high;
+	__u64	low;
+	__u64	ptr[];
+};
+
+#define KEY_FIELD(name, field, offset, size)				\
+	BITMASK(name, struct bkey, field, offset, size)
+
+#define PTR_FIELD(name, offset, size)					\
+static inline __u64 name(const struct bkey *k, unsigned int i)		\
+{ return (k->ptr[i] >> offset) & ~(~0ULL << size); }			\
+									\
+static inline void SET_##name(struct bkey *k, unsigned int i, __u64 v)	\
+{									\
+	k->ptr[i] &= ~(~(~0ULL << size) << offset);			\
+	k->ptr[i] |= (v & ~(~0ULL << size)) << offset;			\
+}
+
+#define KEY_SIZE_BITS		16
+#define KEY_MAX_U64S		8
+
+KEY_FIELD(KEY_PTRS,	high, 60, 3)
+KEY_FIELD(__PAD0,	high, 58, 2)
+KEY_FIELD(KEY_CSUM,	high, 56, 2)
+KEY_FIELD(__PAD1,	high, 55, 1)
+KEY_FIELD(KEY_DIRTY,	high, 36, 1)
+
+KEY_FIELD(KEY_SIZE,	high, 20, KEY_SIZE_BITS)
+KEY_FIELD(KEY_INODE,	high, 0,  20)
+
+/* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */
+
+static inline __u64 KEY_OFFSET(const struct bkey *k)
+{
+	return k->low;
+}
+
+static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
+{
+	k->low = v;
+}
+
+/*
+ * The high bit being set is a relic from when we used it to do binary
+ * searches - it told you where a key started. It's not used anymore,
+ * and can probably be safely dropped.
+ */
+#define KEY(inode, offset, size)					\
+((struct bkey) {							\
+	.high = (1ULL << 63) | ((__u64) (size) << 20) | (inode),	\
+	.low = (offset)							\
+})
+
+#define ZERO_KEY			KEY(0, 0, 0)
+
+#define MAX_KEY_INODE			(~(~0 << 20))
+#define MAX_KEY_OFFSET			(~0ULL >> 1)
+#define MAX_KEY				KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)
+
+#define KEY_START(k)			(KEY_OFFSET(k) - KEY_SIZE(k))
+#define START_KEY(k)			KEY(KEY_INODE(k), KEY_START(k), 0)
+
+#define PTR_DEV_BITS			12
+
+PTR_FIELD(PTR_DEV,			51, PTR_DEV_BITS)
+PTR_FIELD(PTR_OFFSET,			8,  43)
+PTR_FIELD(PTR_GEN,			0,  8)
+
+#define PTR_CHECK_DEV			((1 << PTR_DEV_BITS) - 1)
+
+#define MAKE_PTR(gen, offset, dev)					\
+	((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
+
+/* Bkey utility code */
+
+static inline unsigned long bkey_u64s(const struct bkey *k)
+{
+	return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
+}
+
+static inline unsigned long bkey_bytes(const struct bkey *k)
+{
+	return bkey_u64s(k) * sizeof(__u64);
+}
+
+#define bkey_copy(_dest, _src)	unsafe_memcpy(_dest, _src, bkey_bytes(_src), \
+					/* bkey is always padded */)
+
+static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
+{
+	SET_KEY_INODE(dest, KEY_INODE(src));
+	SET_KEY_OFFSET(dest, KEY_OFFSET(src));
+}
+
+static inline struct bkey *bkey_next(const struct bkey *k)
+{
+	__u64 *d = (void *) k;
+
+	return (struct bkey *) (d + bkey_u64s(k));
+}
+
+static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys)
+{
+	__u64 *d = (void *) k;
+
+	return (struct bkey *) (d + nr_keys);
+}
+/* Enough for a key with 6 pointers */
+#define BKEY_PAD		8
+
+#define BKEY_PADDED(key)					\
+	union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }
+
+/* Superblock */
+
+/* Version 0: Cache device
+ * Version 1: Backing device
+ * Version 2: Seed pointer into btree node checksum
+ * Version 3: Cache device with new UUID format
+ * Version 4: Backing device with data offset
+ */
+#define BCACHE_SB_VERSION_CDEV			0
+#define BCACHE_SB_VERSION_BDEV			1
+#define BCACHE_SB_VERSION_CDEV_WITH_UUID	3
+#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET	4
+#define BCACHE_SB_VERSION_CDEV_WITH_FEATURES	5
+#define BCACHE_SB_VERSION_BDEV_WITH_FEATURES	6
+#define BCACHE_SB_MAX_VERSION			6
+
+#define SB_SECTOR			8
+#define SB_OFFSET			(SB_SECTOR << SECTOR_SHIFT)
+#define SB_SIZE				4096
+#define SB_LABEL_SIZE			32
+#define SB_JOURNAL_BUCKETS		256U
+/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
+#define MAX_CACHES_PER_SET		8
+
+#define BDEV_DATA_START_DEFAULT		16	/* sectors */
+
+struct cache_sb_disk {
+	__le64			csum;
+	__le64			offset;	/* sector where this sb was written */
+	__le64			version;
+
+	__u8			magic[16];
+
+	__u8			uuid[16];
+	union {
+		__u8		set_uuid[16];
+		__le64		set_magic;
+	};
+	__u8			label[SB_LABEL_SIZE];
+
+	__le64			flags;
+	__le64			seq;
+
+	__le64			feature_compat;
+	__le64			feature_incompat;
+	__le64			feature_ro_compat;
+
+	__le64			pad[5];
+
+	union {
+	struct {
+		/* Cache devices */
+		__le64		nbuckets;	/* device size */
+
+		__le16		block_size;	/* sectors */
+		__le16		bucket_size;	/* sectors */
+
+		__le16		nr_in_set;
+		__le16		nr_this_dev;
+	};
+	struct {
+		/* Backing devices */
+		__le64		data_offset;
+
+		/*
+		 * block_size from the cache device section is still used by
+		 * backing devices, so don't add anything here until we fix
+		 * things to not need it for backing devices anymore
+		 */
+	};
+	};
+
+	__le32			last_mount;	/* time overflow in y2106 */
+
+	__le16			first_bucket;
+	union {
+		__le16		njournal_buckets;
+		__le16		keys;
+	};
+	__le64			d[SB_JOURNAL_BUCKETS];	/* journal buckets */
+	__le16			obso_bucket_size_hi;	/* obsoleted */
+};
+
+/*
+ * This is for in-memory bcache super block.
+ * NOTE: cache_sb is NOT exactly mapping to cache_sb_disk, the member
+ *       size, ordering and even whole struct size may be different
+ *       from cache_sb_disk.
+ */
+struct cache_sb {
+	__u64			offset;	/* sector where this sb was written */
+	__u64			version;
+
+	__u8			magic[16];
+
+	__u8			uuid[16];
+	union {
+		__u8		set_uuid[16];
+		__u64		set_magic;
+	};
+	__u8			label[SB_LABEL_SIZE];
+
+	__u64			flags;
+	__u64			seq;
+
+	__u64			feature_compat;
+	__u64			feature_incompat;
+	__u64			feature_ro_compat;
+
+	union {
+	struct {
+		/* Cache devices */
+		__u64		nbuckets;	/* device size */
+
+		__u16		block_size;	/* sectors */
+		__u16		nr_in_set;
+		__u16		nr_this_dev;
+		__u32		bucket_size;	/* sectors */
+	};
+	struct {
+		/* Backing devices */
+		__u64		data_offset;
+
+		/*
+		 * block_size from the cache device section is still used by
+		 * backing devices, so don't add anything here until we fix
+		 * things to not need it for backing devices anymore
+		 */
+	};
+	};
+
+	__u32			last_mount;	/* time overflow in y2106 */
+
+	__u16			first_bucket;
+	union {
+		__u16		njournal_buckets;
+		__u16		keys;
+	};
+	__u64			d[SB_JOURNAL_BUCKETS];	/* journal buckets */
+};
+
+static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
+{
+	return sb->version == BCACHE_SB_VERSION_BDEV
+		|| sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET
+		|| sb->version == BCACHE_SB_VERSION_BDEV_WITH_FEATURES;
+}
+
+BITMASK(CACHE_SYNC,			struct cache_sb, flags, 0, 1);
+BITMASK(CACHE_DISCARD,			struct cache_sb, flags, 1, 1);
+BITMASK(CACHE_REPLACEMENT,		struct cache_sb, flags, 2, 3);
+#define CACHE_REPLACEMENT_LRU		0U
+#define CACHE_REPLACEMENT_FIFO		1U
+#define CACHE_REPLACEMENT_RANDOM	2U
+
+BITMASK(BDEV_CACHE_MODE,		struct cache_sb, flags, 0, 4);
+#define CACHE_MODE_WRITETHROUGH		0U
+#define CACHE_MODE_WRITEBACK		1U
+#define CACHE_MODE_WRITEAROUND		2U
+#define CACHE_MODE_NONE			3U
+BITMASK(BDEV_STATE,			struct cache_sb, flags, 61, 2);
+#define BDEV_STATE_NONE			0U
+#define BDEV_STATE_CLEAN		1U
+#define BDEV_STATE_DIRTY		2U
+#define BDEV_STATE_STALE		3U
+
+/*
+ * Magic numbers
+ *
+ * The various other data structures have their own magic numbers, which are
+ * xored with the first part of the cache set's UUID
+ */
+
+#define JSET_MAGIC			0x245235c1a3625032ULL
+#define PSET_MAGIC			0x6750e15f87337f91ULL
+#define BSET_MAGIC			0x90135c78b99e07f5ULL
+
+static inline __u64 jset_magic(struct cache_sb *sb)
+{
+	return sb->set_magic ^ JSET_MAGIC;
+}
+
+static inline __u64 pset_magic(struct cache_sb *sb)
+{
+	return sb->set_magic ^ PSET_MAGIC;
+}
+
+static inline __u64 bset_magic(struct cache_sb *sb)
+{
+	return sb->set_magic ^ BSET_MAGIC;
+}
+
+/*
+ * Journal
+ *
+ * On disk format for a journal entry:
+ * seq is monotonically increasing; every journal entry has its own unique
+ * sequence number.
+ *
+ * last_seq is the oldest journal entry that still has keys the btree hasn't
+ * flushed to disk yet.
+ *
+ * version is for on disk format changes.
+ */
+
+#define BCACHE_JSET_VERSION_UUIDv1	1
+#define BCACHE_JSET_VERSION_UUID	1	/* Always latest UUID format */
+#define BCACHE_JSET_VERSION		1
+
+struct jset {
+	__u64			csum;
+	__u64			magic;
+	__u64			seq;
+	__u32			version;
+	__u32			keys;
+
+	__u64			last_seq;
+
+	BKEY_PADDED(uuid_bucket);
+	BKEY_PADDED(btree_root);
+	__u16			btree_level;
+	__u16			pad[3];
+
+	__u64			prio_bucket[MAX_CACHES_PER_SET];
+
+	union {
+		DECLARE_FLEX_ARRAY(struct bkey, start);
+		DECLARE_FLEX_ARRAY(__u64, d);
+	};
+};
+
+/* Bucket prios/gens */
+
+struct prio_set {
+	__u64			csum;
+	__u64			magic;
+	__u64			seq;
+	__u32			version;
+	__u32			pad;
+
+	__u64			next_bucket;
+
+	struct bucket_disk {
+		__u16		prio;
+		__u8		gen;
+	} __attribute((packed)) data[];
+};
+
+/* UUIDS - per backing device/flash only volume metadata */
+
+struct uuid_entry {
+	union {
+		struct {
+			__u8	uuid[16];
+			__u8	label[32];
+			__u32	first_reg; /* time overflow in y2106 */
+			__u32	last_reg;
+			__u32	invalidated;
+
+			__u32	flags;
+			/* Size of flash only volumes */
+			__u64	sectors;
+		};
+
+		__u8		pad[128];
+	};
+};
+
+BITMASK(UUID_FLASH_ONLY,	struct uuid_entry, flags, 0, 1);
+
+/* Btree nodes */
+
+/* Version 1: Seed pointer into btree node checksum
+ */
+#define BCACHE_BSET_CSUM		1
+#define BCACHE_BSET_VERSION		1
+
+/*
+ * Btree nodes
+ *
+ * On disk a btree node is a list/log of these; within each set the keys are
+ * sorted
+ */
+struct bset {
+	__u64			csum;
+	__u64			magic;
+	__u64			seq;
+	__u32			version;
+	__u32			keys;
+
+	union {
+		DECLARE_FLEX_ARRAY(struct bkey, start);
+		DECLARE_FLEX_ARRAY(__u64, d);
+	};
+};
+
+/* OBSOLETE */
+
+/* UUIDS - per backing device/flash only volume metadata */
+
+struct uuid_entry_v0 {
+	__u8		uuid[16];
+	__u8		label[32];
+	__u32		first_reg;
+	__u32		last_reg;
+	__u32		invalidated;
+	__u32		pad;
+};
+
+#endif /* _LINUX_BCACHE_H */

linux-7.2.3/drivers/md/bcache/bset.h

@@ -0,0 +1,605 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_BSET_H
+#define _BCACHE_BSET_H
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+
+#include "bcache_ondisk.h"
+#include "util.h" /* for time_stats */
+
+/*
+ * BKEYS:
+ *
+ * A bkey contains a key, a size field, a variable number of pointers, and some
+ * ancillary flag bits.
+ *
+ * We use two different functions for validating bkeys, bch_ptr_invalid and
+ * bch_ptr_bad().
+ *
+ * bch_ptr_invalid() primarily filters out keys and pointers that would be
+ * invalid due to some sort of bug, whereas bch_ptr_bad() filters out keys and
+ * pointer that occur in normal practice but don't point to real data.
+ *
+ * The one exception to the rule that ptr_invalid() filters out invalid keys is
+ * that it also filters out keys of size 0 - these are keys that have been
+ * completely overwritten. It'd be safe to delete these in memory while leaving
+ * them on disk, just unnecessary work - so we filter them out when resorting
+ * instead.
+ *
+ * We can't filter out stale keys when we're resorting, because garbage
+ * collection needs to find them to ensure bucket gens don't wrap around -
+ * unless we're rewriting the btree node those stale keys still exist on disk.
+ *
+ * We also implement functions here for removing some number of sectors from the
+ * front or the back of a bkey - this is mainly used for fixing overlapping
+ * extents, by removing the overlapping sectors from the older key.
+ *
+ * BSETS:
+ *
+ * A bset is an array of bkeys laid out contiguously in memory in sorted order,
+ * along with a header. A btree node is made up of a number of these, written at
+ * different times.
+ *
+ * There could be many of them on disk, but we never allow there to be more than
+ * 4 in memory - we lazily resort as needed.
+ *
+ * We implement code here for creating and maintaining auxiliary search trees
+ * (described below) for searching an individial bset, and on top of that we
+ * implement a btree iterator.
+ *
+ * BTREE ITERATOR:
+ *
+ * Most of the code in bcache doesn't care about an individual bset - it needs
+ * to search entire btree nodes and iterate over them in sorted order.
+ *
+ * The btree iterator code serves both functions; it iterates through the keys
+ * in a btree node in sorted order, starting from either keys after a specific
+ * point (if you pass it a search key) or the start of the btree node.
+ *
+ * AUXILIARY SEARCH TREES:
+ *
+ * Since keys are variable length, we can't use a binary search on a bset - we
+ * wouldn't be able to find the start of the next key. But binary searches are
+ * slow anyways, due to terrible cache behaviour; bcache originally used binary
+ * searches and that code topped out at under 50k lookups/second.
+ *
+ * So we need to construct some sort of lookup table. Since we only insert keys
+ * into the last (unwritten) set, most of the keys within a given btree node are
+ * usually in sets that are mostly constant. We use two different types of
+ * lookup tables to take advantage of this.
+ *
+ * Both lookup tables share in common that they don't index every key in the
+ * set; they index one key every BSET_CACHELINE bytes, and then a linear search
+ * is used for the rest.
+ *
+ * For sets that have been written to disk and are no longer being inserted
+ * into, we construct a binary search tree in an array - traversing a binary
+ * search tree in an array gives excellent locality of reference and is very
+ * fast, since both children of any node are adjacent to each other in memory
+ * (and their grandchildren, and great grandchildren...) - this means
+ * prefetching can be used to great effect.
+ *
+ * It's quite useful performance wise to keep these nodes small - not just
+ * because they're more likely to be in L2, but also because we can prefetch
+ * more nodes on a single cacheline and thus prefetch more iterations in advance
+ * when traversing this tree.
+ *
+ * Nodes in the auxiliary search tree must contain both a key to compare against
+ * (we don't want to fetch the key from the set, that would defeat the purpose),
+ * and a pointer to the key. We use a few tricks to compress both of these.
+ *
+ * To compress the pointer, we take advantage of the fact that one node in the
+ * search tree corresponds to precisely BSET_CACHELINE bytes in the set. We have
+ * a function (to_inorder()) that takes the index of a node in a binary tree and
+ * returns what its index would be in an inorder traversal, so we only have to
+ * store the low bits of the offset.
+ *
+ * The key is 84 bits (KEY_DEV + key->key, the offset on the device). To
+ * compress that,  we take advantage of the fact that when we're traversing the
+ * search tree at every iteration we know that both our search key and the key
+ * we're looking for lie within some range - bounded by our previous
+ * comparisons. (We special case the start of a search so that this is true even
+ * at the root of the tree).
+ *
+ * So we know the key we're looking for is between a and b, and a and b don't
+ * differ higher than bit 50, we don't need to check anything higher than bit
+ * 50.
+ *
+ * We don't usually need the rest of the bits, either; we only need enough bits
+ * to partition the key range we're currently checking.  Consider key n - the
+ * key our auxiliary search tree node corresponds to, and key p, the key
+ * immediately preceding n.  The lowest bit we need to store in the auxiliary
+ * search tree is the highest bit that differs between n and p.
+ *
+ * Note that this could be bit 0 - we might sometimes need all 80 bits to do the
+ * comparison. But we'd really like our nodes in the auxiliary search tree to be
+ * of fixed size.
+ *
+ * The solution is to make them fixed size, and when we're constructing a node
+ * check if p and n differed in the bits we needed them to. If they don't we
+ * flag that node, and when doing lookups we fallback to comparing against the
+ * real key. As long as this doesn't happen to often (and it seems to reliably
+ * happen a bit less than 1% of the time), we win - even on failures, that key
+ * is then more likely to be in cache than if we were doing binary searches all
+ * the way, since we're touching so much less memory.
+ *
+ * The keys in the auxiliary search tree are stored in (software) floating
+ * point, with an exponent and a mantissa. The exponent needs to be big enough
+ * to address all the bits in the original key, but the number of bits in the
+ * mantissa is somewhat arbitrary; more bits just gets us fewer failures.
+ *
+ * We need 7 bits for the exponent and 3 bits for the key's offset (since keys
+ * are 8 byte aligned); using 22 bits for the mantissa means a node is 4 bytes.
+ * We need one node per 128 bytes in the btree node, which means the auxiliary
+ * search trees take up 3% as much memory as the btree itself.
+ *
+ * Constructing these auxiliary search trees is moderately expensive, and we
+ * don't want to be constantly rebuilding the search tree for the last set
+ * whenever we insert another key into it. For the unwritten set, we use a much
+ * simpler lookup table - it's just a flat array, so index i in the lookup table
+ * corresponds to the i range of BSET_CACHELINE bytes in the set. Indexing
+ * within each byte range works the same as with the auxiliary search trees.
+ *
+ * These are much easier to keep up to date when we insert a key - we do it
+ * somewhat lazily; when we shift a key up we usually just increment the pointer
+ * to it, only when it would overflow do we go to the trouble of finding the
+ * first key in that range of bytes again.
+ */
+
+struct btree_keys;
+struct btree_iter;
+struct btree_iter_set;
+struct bkey_float;
+
+#define MAX_BSETS		4U
+
+struct bset_tree {
+	/*
+	 * We construct a binary tree in an array as if the array
+	 * started at 1, so that things line up on the same cachelines
+	 * better: see comments in bset.c at cacheline_to_bkey() for
+	 * details
+	 */
+
+	/* size of the binary tree and prev array */
+	unsigned int		size;
+
+	/* function of size - precalculated for to_inorder() */
+	unsigned int		extra;
+
+	/* copy of the last key in the set */
+	struct bkey		end;
+	struct bkey_float	*tree;
+
+	/*
+	 * The nodes in the bset tree point to specific keys - this
+	 * array holds the sizes of the previous key.
+	 *
+	 * Conceptually it's a member of struct bkey_float, but we want
+	 * to keep bkey_float to 4 bytes and prev isn't used in the fast
+	 * path.
+	 */
+	uint8_t			*prev;
+
+	/* The actual btree node, with pointers to each sorted set */
+	struct bset		*data;
+};
+
+struct btree_keys_ops {
+	bool		(*sort_cmp)(struct btree_iter_set l,
+				    struct btree_iter_set r);
+	struct bkey	*(*sort_fixup)(struct btree_iter *iter,
+				       struct bkey *tmp);
+	bool		(*insert_fixup)(struct btree_keys *b,
+					struct bkey *insert,
+					struct btree_iter *iter,
+					struct bkey *replace_key);
+	bool		(*key_invalid)(struct btree_keys *bk,
+				       const struct bkey *k);
+	bool		(*key_bad)(struct btree_keys *bk,
+				   const struct bkey *k);
+	bool		(*key_merge)(struct btree_keys *bk,
+				     struct bkey *l, struct bkey *r);
+	void		(*key_to_text)(char *buf,
+				       size_t size,
+				       const struct bkey *k);
+	void		(*key_dump)(struct btree_keys *keys,
+				    const struct bkey *k);
+
+	/*
+	 * Only used for deciding whether to use START_KEY(k) or just the key
+	 * itself in a couple places
+	 */
+	bool		is_extents;
+};
+
+struct btree_keys {
+	const struct btree_keys_ops	*ops;
+	uint8_t			page_order;
+	uint8_t			nsets;
+	unsigned int		last_set_unwritten:1;
+	bool			*expensive_debug_checks;
+
+	/*
+	 * Sets of sorted keys - the real btree node - plus a binary search tree
+	 *
+	 * set[0] is special; set[0]->tree, set[0]->prev and set[0]->data point
+	 * to the memory we have allocated for this btree node. Additionally,
+	 * set[0]->data points to the entire btree node as it exists on disk.
+	 */
+	struct bset_tree	set[MAX_BSETS];
+};
+
+static inline struct bset_tree *bset_tree_last(struct btree_keys *b)
+{
+	return b->set + b->nsets;
+}
+
+static inline bool bset_written(struct btree_keys *b, struct bset_tree *t)
+{
+	return t <= b->set + b->nsets - b->last_set_unwritten;
+}
+
+static inline bool bkey_written(struct btree_keys *b, struct bkey *k)
+{
+	return !b->last_set_unwritten || k < b->set[b->nsets].data->start;
+}
+
+static inline unsigned int bset_byte_offset(struct btree_keys *b,
+					    struct bset *i)
+{
+	return ((size_t) i) - ((size_t) b->set->data);
+}
+
+static inline unsigned int bset_sector_offset(struct btree_keys *b,
+					      struct bset *i)
+{
+	return bset_byte_offset(b, i) >> 9;
+}
+
+#define __set_bytes(i, k)	(sizeof(*(i)) + (k) * sizeof(uint64_t))
+#define set_bytes(i)		__set_bytes(i, i->keys)
+
+#define __set_blocks(i, k, block_bytes)				\
+	DIV_ROUND_UP(__set_bytes(i, k), block_bytes)
+#define set_blocks(i, block_bytes)				\
+	__set_blocks(i, (i)->keys, block_bytes)
+
+static inline size_t bch_btree_keys_u64s_remaining(struct btree_keys *b)
+{
+	struct bset_tree *t = bset_tree_last(b);
+
+	BUG_ON((PAGE_SIZE << b->page_order) <
+	       (bset_byte_offset(b, t->data) + set_bytes(t->data)));
+
+	if (!b->last_set_unwritten)
+		return 0;
+
+	return ((PAGE_SIZE << b->page_order) -
+		(bset_byte_offset(b, t->data) + set_bytes(t->data))) /
+		sizeof(u64);
+}
+
+static inline struct bset *bset_next_set(struct btree_keys *b,
+					 unsigned int block_bytes)
+{
+	struct bset *i = bset_tree_last(b)->data;
+
+	return ((void *) i) + roundup(set_bytes(i), block_bytes);
+}
+
+void bch_btree_keys_free(struct btree_keys *b);
+int bch_btree_keys_alloc(struct btree_keys *b, unsigned int page_order,
+			 gfp_t gfp);
+void bch_btree_keys_init(struct btree_keys *b, const struct btree_keys_ops *ops,
+			 bool *expensive_debug_checks);
+
+void bch_bset_init_next(struct btree_keys *b, struct bset *i, uint64_t magic);
+void bch_bset_build_written_tree(struct btree_keys *b);
+void bch_bset_fix_invalidated_key(struct btree_keys *b, struct bkey *k);
+bool bch_bkey_try_merge(struct btree_keys *b, struct bkey *l, struct bkey *r);
+void bch_bset_insert(struct btree_keys *b, struct bkey *where,
+		     struct bkey *insert);
+unsigned int bch_btree_insert_key(struct btree_keys *b, struct bkey *k,
+			      struct bkey *replace_key);
+
+enum {
+	BTREE_INSERT_STATUS_NO_INSERT = 0,
+	BTREE_INSERT_STATUS_INSERT,
+	BTREE_INSERT_STATUS_BACK_MERGE,
+	BTREE_INSERT_STATUS_OVERWROTE,
+	BTREE_INSERT_STATUS_FRONT_MERGE,
+};
+
+/* Btree key iteration */
+
+struct btree_iter {
+	size_t size, used;
+#ifdef CONFIG_BCACHE_DEBUG
+	struct btree_keys *b;
+#endif
+	struct btree_iter_set {
+		struct bkey *k, *end;
+	} data[];
+};
+
+/* Fixed-size btree_iter that can be allocated on the stack */
+
+struct btree_iter_stack {
+	/* Must be last as it ends in a flexible-array member. */
+	TRAILING_OVERLAP(struct btree_iter, iter, data,
+		struct btree_iter_set stack_data[MAX_BSETS];
+	);
+};
+static_assert(offsetof(struct btree_iter_stack, iter.data) ==
+	      offsetof(struct btree_iter_stack, stack_data));
+
+typedef bool (*ptr_filter_fn)(struct btree_keys *b, const struct bkey *k);
+
+struct bkey *bch_btree_iter_next(struct btree_iter *iter);
+struct bkey *bch_btree_iter_next_filter(struct btree_iter *iter,
+					struct btree_keys *b,
+					ptr_filter_fn fn);
+
+void bch_btree_iter_push(struct btree_iter *iter, struct bkey *k,
+			 struct bkey *end);
+struct bkey *bch_btree_iter_stack_init(struct btree_keys *b,
+				       struct btree_iter_stack *iter,
+				       struct bkey *search);
+
+struct bkey *__bch_bset_search(struct btree_keys *b, struct bset_tree *t,
+			       const struct bkey *search);
+
+/*
+ * Returns the first key that is strictly greater than search
+ */
+static inline struct bkey *bch_bset_search(struct btree_keys *b,
+					   struct bset_tree *t,
+					   const struct bkey *search)
+{
+	return search ? __bch_bset_search(b, t, search) : t->data->start;
+}
+
+#define for_each_key_filter(b, k, stack_iter, filter)                      \
+	for (bch_btree_iter_stack_init((b), (stack_iter), NULL);           \
+	     ((k) = bch_btree_iter_next_filter(&((stack_iter)->iter), (b), \
+					       filter));)
+
+#define for_each_key(b, k, stack_iter)                           \
+	for (bch_btree_iter_stack_init((b), (stack_iter), NULL); \
+	     ((k) = bch_btree_iter_next(&((stack_iter)->iter)));)
+
+/* Sorting */
+
+struct bset_sort_state {
+	mempool_t		pool;
+
+	unsigned int		page_order;
+	unsigned int		crit_factor;
+
+	struct time_stats	time;
+};
+
+void bch_bset_sort_state_free(struct bset_sort_state *state);
+int bch_bset_sort_state_init(struct bset_sort_state *state,
+			     unsigned int page_order);
+void bch_btree_sort_lazy(struct btree_keys *b, struct bset_sort_state *state);
+void bch_btree_sort_into(struct btree_keys *b, struct btree_keys *new,
+			 struct bset_sort_state *state);
+void bch_btree_sort_and_fix_extents(struct btree_keys *b,
+				    struct btree_iter *iter,
+				    struct bset_sort_state *state);
+void bch_btree_sort_partial(struct btree_keys *b, unsigned int start,
+			    struct bset_sort_state *state);
+
+static inline void bch_btree_sort(struct btree_keys *b,
+				  struct bset_sort_state *state)
+{
+	bch_btree_sort_partial(b, 0, state);
+}
+
+struct bset_stats {
+	size_t sets_written, sets_unwritten;
+	size_t bytes_written, bytes_unwritten;
+	size_t floats, failed;
+};
+
+void bch_btree_keys_stats(struct btree_keys *b, struct bset_stats *state);
+
+/* Bkey utility code */
+
+#define bset_bkey_last(i)	bkey_idx((struct bkey *) (i)->d, \
+					 (unsigned int)(i)->keys)
+
+static inline struct bkey *bset_bkey_idx(struct bset *i, unsigned int idx)
+{
+	return bkey_idx(i->start, idx);
+}
+
+static inline void bkey_init(struct bkey *k)
+{
+	*k = ZERO_KEY;
+}
+
+static __always_inline int64_t bkey_cmp(const struct bkey *l,
+					const struct bkey *r)
+{
+	return unlikely(KEY_INODE(l) != KEY_INODE(r))
+		? (int64_t) KEY_INODE(l) - (int64_t) KEY_INODE(r)
+		: (int64_t) KEY_OFFSET(l) - (int64_t) KEY_OFFSET(r);
+}
+
+void bch_bkey_copy_single_ptr(struct bkey *dest, const struct bkey *src,
+			      unsigned int i);
+bool __bch_cut_front(const struct bkey *where, struct bkey *k);
+bool __bch_cut_back(const struct bkey *where, struct bkey *k);
+
+static inline bool bch_cut_front(const struct bkey *where, struct bkey *k)
+{
+	BUG_ON(bkey_cmp(where, k) > 0);
+	return __bch_cut_front(where, k);
+}
+
+static inline bool bch_cut_back(const struct bkey *where, struct bkey *k)
+{
+	BUG_ON(bkey_cmp(where, &START_KEY(k)) < 0);
+	return __bch_cut_back(where, k);
+}
+
+/*
+ * Pointer '*preceding_key_p' points to a memory object to store preceding
+ * key of k. If the preceding key does not exist, set '*preceding_key_p' to
+ * NULL. So the caller of preceding_key() needs to take care of memory
+ * which '*preceding_key_p' pointed to before calling preceding_key().
+ * Currently the only caller of preceding_key() is bch_btree_insert_key(),
+ * and it points to an on-stack variable, so the memory release is handled
+ * by stackframe itself.
+ */
+static inline void preceding_key(struct bkey *k, struct bkey **preceding_key_p)
+{
+	if (KEY_INODE(k) || KEY_OFFSET(k)) {
+		(**preceding_key_p) = KEY(KEY_INODE(k), KEY_OFFSET(k), 0);
+		if (!(*preceding_key_p)->low)
+			(*preceding_key_p)->high--;
+		(*preceding_key_p)->low--;
+	} else {
+		(*preceding_key_p) = NULL;
+	}
+}
+
+static inline bool bch_ptr_invalid(struct btree_keys *b, const struct bkey *k)
+{
+	return b->ops->key_invalid(b, k);
+}
+
+static inline bool bch_ptr_bad(struct btree_keys *b, const struct bkey *k)
+{
+	return b->ops->key_bad(b, k);
+}
+
+static inline void bch_bkey_to_text(struct btree_keys *b, char *buf,
+				    size_t size, const struct bkey *k)
+{
+	return b->ops->key_to_text(buf, size, k);
+}
+
+static inline bool bch_bkey_equal_header(const struct bkey *l,
+					 const struct bkey *r)
+{
+	return (KEY_DIRTY(l) == KEY_DIRTY(r) &&
+		KEY_PTRS(l) == KEY_PTRS(r) &&
+		KEY_CSUM(l) == KEY_CSUM(r));
+}
+
+/* Keylists */
+
+struct keylist {
+	union {
+		struct bkey		*keys;
+		uint64_t		*keys_p;
+	};
+	union {
+		struct bkey		*top;
+		uint64_t		*top_p;
+	};
+
+	/* Enough room for btree_split's keys without realloc */
+#define KEYLIST_INLINE		16
+	uint64_t		inline_keys[KEYLIST_INLINE];
+};
+
+static inline void bch_keylist_init(struct keylist *l)
+{
+	l->top_p = l->keys_p = l->inline_keys;
+}
+
+static inline void bch_keylist_init_single(struct keylist *l, struct bkey *k)
+{
+	l->keys = k;
+	l->top = bkey_next(k);
+}
+
+static inline void bch_keylist_push(struct keylist *l)
+{
+	l->top = bkey_next(l->top);
+}
+
+static inline void bch_keylist_add(struct keylist *l, struct bkey *k)
+{
+	bkey_copy(l->top, k);
+	bch_keylist_push(l);
+}
+
+static inline bool bch_keylist_empty(struct keylist *l)
+{
+	return l->top == l->keys;
+}
+
+static inline void bch_keylist_reset(struct keylist *l)
+{
+	l->top = l->keys;
+}
+
+static inline void bch_keylist_free(struct keylist *l)
+{
+	if (l->keys_p != l->inline_keys)
+		kfree(l->keys_p);
+}
+
+static inline size_t bch_keylist_nkeys(struct keylist *l)
+{
+	return l->top_p - l->keys_p;
+}
+
+static inline size_t bch_keylist_bytes(struct keylist *l)
+{
+	return bch_keylist_nkeys(l) * sizeof(uint64_t);
+}
+
+struct bkey *bch_keylist_pop(struct keylist *l);
+void bch_keylist_pop_front(struct keylist *l);
+int __bch_keylist_realloc(struct keylist *l, unsigned int u64s);
+
+/* Debug stuff */
+
+#ifdef CONFIG_BCACHE_DEBUG
+
+int __bch_count_data(struct btree_keys *b);
+void __printf(2, 3) __bch_check_keys(struct btree_keys *b,
+				     const char *fmt,
+				     ...);
+void bch_dump_bset(struct btree_keys *b, struct bset *i, unsigned int set);
+void bch_dump_bucket(struct btree_keys *b);
+
+#else
+
+static inline int __bch_count_data(struct btree_keys *b) { return -1; }
+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 *b, struct bset *i, unsigned int set);
+
+#endif
+
+static inline bool btree_keys_expensive_checks(struct btree_keys *b)
+{
+#ifdef CONFIG_BCACHE_DEBUG
+	return *b->expensive_debug_checks;
+#else
+	return false;
+#endif
+}
+
+static inline int bch_count_data(struct btree_keys *b)
+{
+	return btree_keys_expensive_checks(b) ? __bch_count_data(b) : -1;
+}
+
+#define bch_check_keys(b, ...)						\
+do {									\
+	if (btree_keys_expensive_checks(b))				\
+		__bch_check_keys(b, __VA_ARGS__);			\
+} while (0)
+
+#endif

linux-7.2.3/drivers/md/bcache/btree.h

@@ -0,0 +1,417 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_BTREE_H
+#define _BCACHE_BTREE_H
+
+/*
+ * THE BTREE:
+ *
+ * At a high level, bcache's btree is relatively standard b+ tree. All keys and
+ * pointers are in the leaves; interior nodes only have pointers to the child
+ * nodes.
+ *
+ * In the interior nodes, a struct bkey always points to a child btree node, and
+ * the key is the highest key in the child node - except that the highest key in
+ * an interior node is always MAX_KEY. The size field refers to the size on disk
+ * of the child node - this would allow us to have variable sized btree nodes
+ * (handy for keeping the depth of the btree 1 by expanding just the root).
+ *
+ * Btree nodes are themselves log structured, but this is hidden fairly
+ * thoroughly. Btree nodes on disk will in practice have extents that overlap
+ * (because they were written at different times), but in memory we never have
+ * overlapping extents - when we read in a btree node from disk, the first thing
+ * we do is resort all the sets of keys with a mergesort, and in the same pass
+ * we check for overlapping extents and adjust them appropriately.
+ *
+ * struct btree_op is a central interface to the btree code. It's used for
+ * specifying read vs. write locking, and the embedded closure is used for
+ * waiting on IO or reserve memory.
+ *
+ * BTREE CACHE:
+ *
+ * Btree nodes are cached in memory; traversing the btree might require reading
+ * in btree nodes which is handled mostly transparently.
+ *
+ * bch_btree_node_get() looks up a btree node in the cache and reads it in from
+ * disk if necessary. This function is almost never called directly though - the
+ * btree() macro is used to get a btree node, call some function on it, and
+ * unlock the node after the function returns.
+ *
+ * The root is special cased - it's taken out of the cache's lru (thus pinning
+ * it in memory), so we can find the root of the btree by just dereferencing a
+ * pointer instead of looking it up in the cache. This makes locking a bit
+ * tricky, since the root pointer is protected by the lock in the btree node it
+ * points to - the btree_root() macro handles this.
+ *
+ * In various places we must be able to allocate memory for multiple btree nodes
+ * in order to make forward progress. To do this we use the btree cache itself
+ * as a reserve; if __get_free_pages() fails, we'll find a node in the btree
+ * cache we can reuse. We can't allow more than one thread to be doing this at a
+ * time, so there's a lock, implemented by a pointer to the btree_op closure -
+ * this allows the btree_root() macro to implicitly release this lock.
+ *
+ * BTREE IO:
+ *
+ * Btree nodes never have to be explicitly read in; bch_btree_node_get() handles
+ * this.
+ *
+ * For writing, we have two btree_write structs embeddded in struct btree - one
+ * write in flight, and one being set up, and we toggle between them.
+ *
+ * Writing is done with a single function -  bch_btree_write() really serves two
+ * different purposes and should be broken up into two different functions. When
+ * passing now = false, it merely indicates that the node is now dirty - calling
+ * it ensures that the dirty keys will be written at some point in the future.
+ *
+ * When passing now = true, bch_btree_write() causes a write to happen
+ * "immediately" (if there was already a write in flight, it'll cause the write
+ * to happen as soon as the previous write completes). It returns immediately
+ * though - but it takes a refcount on the closure in struct btree_op you passed
+ * to it, so a closure_sync() later can be used to wait for the write to
+ * complete.
+ *
+ * This is handy because btree_split() and garbage collection can issue writes
+ * in parallel, reducing the amount of time they have to hold write locks.
+ *
+ * LOCKING:
+ *
+ * When traversing the btree, we may need write locks starting at some level -
+ * inserting a key into the btree will typically only require a write lock on
+ * the leaf node.
+ *
+ * This is specified with the lock field in struct btree_op; lock = 0 means we
+ * take write locks at level <= 0, i.e. only leaf nodes. bch_btree_node_get()
+ * checks this field and returns the node with the appropriate lock held.
+ *
+ * If, after traversing the btree, the insertion code discovers it has to split
+ * then it must restart from the root and take new locks - to do this it changes
+ * the lock field and returns -EINTR, which causes the btree_root() macro to
+ * loop.
+ *
+ * Handling cache misses require a different mechanism for upgrading to a write
+ * lock. We do cache lookups with only a read lock held, but if we get a cache
+ * miss and we wish to insert this data into the cache, we have to insert a
+ * placeholder key to detect races - otherwise, we could race with a write and
+ * overwrite the data that was just written to the cache with stale data from
+ * the backing device.
+ *
+ * For this we use a sequence number that write locks and unlocks increment - to
+ * insert the check key it unlocks the btree node and then takes a write lock,
+ * and fails if the sequence number doesn't match.
+ */
+
+#include "bset.h"
+#include "debug.h"
+
+struct btree_write {
+	atomic_t		*journal;
+
+	/* If btree_split() frees a btree node, it writes a new pointer to that
+	 * btree node indicating it was freed; it takes a refcount on
+	 * c->prio_blocked because we can't write the gens until the new
+	 * pointer is on disk. This allows btree_write_endio() to release the
+	 * refcount that btree_split() took.
+	 */
+	int			prio_blocked;
+};
+
+struct btree {
+	/* Hottest entries first */
+	struct hlist_node	hash;
+
+	/* Key/pointer for this btree node */
+	BKEY_PADDED(key);
+
+	unsigned long		seq;
+	struct rw_semaphore	lock;
+	struct cache_set	*c;
+	struct btree		*parent;
+
+	struct mutex		write_lock;
+
+	unsigned long		flags;
+	uint16_t		written;	/* would be nice to kill */
+	uint8_t			level;
+
+	struct btree_keys	keys;
+
+	/* For outstanding btree writes, used as a lock - protects write_idx */
+	struct closure		io;
+	struct semaphore	io_mutex;
+
+	struct list_head	list;
+	struct delayed_work	work;
+
+	struct btree_write	writes[2];
+	struct bio		*bio;
+};
+
+
+
+
+#define BTREE_FLAG(flag)						\
+static inline bool btree_node_ ## flag(struct btree *b)			\
+{	return test_bit(BTREE_NODE_ ## flag, &b->flags); }		\
+									\
+static inline void set_btree_node_ ## flag(struct btree *b)		\
+{	set_bit(BTREE_NODE_ ## flag, &b->flags); }
+
+enum btree_flags {
+	BTREE_NODE_io_error,
+	BTREE_NODE_dirty,
+	BTREE_NODE_write_idx,
+	BTREE_NODE_journal_flush,
+};
+
+BTREE_FLAG(io_error);
+BTREE_FLAG(dirty);
+BTREE_FLAG(write_idx);
+BTREE_FLAG(journal_flush);
+
+static inline struct btree_write *btree_current_write(struct btree *b)
+{
+	return b->writes + btree_node_write_idx(b);
+}
+
+static inline struct btree_write *btree_prev_write(struct btree *b)
+{
+	return b->writes + (btree_node_write_idx(b) ^ 1);
+}
+
+static inline struct bset *btree_bset_first(struct btree *b)
+{
+	return b->keys.set->data;
+}
+
+static inline struct bset *btree_bset_last(struct btree *b)
+{
+	return bset_tree_last(&b->keys)->data;
+}
+
+static inline unsigned int bset_block_offset(struct btree *b, struct bset *i)
+{
+	return bset_sector_offset(&b->keys, i) >> b->c->block_bits;
+}
+
+static inline void set_gc_sectors(struct cache_set *c)
+{
+	atomic_set(&c->sectors_to_gc, c->cache->sb.bucket_size * c->nbuckets / 16);
+}
+
+void bkey_put(struct cache_set *c, struct bkey *k);
+
+/* Looping macros */
+
+#define for_each_cached_btree(b, c, iter)				\
+	for (iter = 0;							\
+	     iter < ARRAY_SIZE((c)->bucket_hash);			\
+	     iter++)							\
+		hlist_for_each_entry_rcu((b), (c)->bucket_hash + iter, hash)
+
+/* Recursing down the btree */
+
+struct btree_op {
+	/* for waiting on btree reserve in btree_split() */
+	wait_queue_entry_t		wait;
+
+	/* Btree level at which we start taking write locks */
+	short			lock;
+
+	unsigned int		insert_collision:1;
+};
+
+struct btree_check_state;
+struct btree_check_info {
+	struct btree_check_state	*state;
+	struct task_struct		*thread;
+	int				result;
+};
+
+#define BCH_BTR_CHKTHREAD_MAX	12
+struct btree_check_state {
+	struct cache_set		*c;
+	int				total_threads;
+	int				key_idx;
+	spinlock_t			idx_lock;
+	atomic_t			started;
+	atomic_t			enough;
+	wait_queue_head_t		wait;
+	struct btree_check_info		infos[BCH_BTR_CHKTHREAD_MAX];
+};
+
+static inline void bch_btree_op_init(struct btree_op *op, int write_lock_level)
+{
+	memset(op, 0, sizeof(struct btree_op));
+	init_wait(&op->wait);
+	op->lock = write_lock_level;
+}
+
+static inline void rw_lock(bool w, struct btree *b, int level)
+{
+	w ? down_write(&b->lock)
+	  : down_read(&b->lock);
+	if (w)
+		b->seq++;
+}
+
+static inline void rw_unlock(bool w, struct btree *b)
+{
+	if (w)
+		b->seq++;
+	(w ? up_write : up_read)(&b->lock);
+}
+
+void bch_btree_node_read_done(struct btree *b);
+void __bch_btree_node_write(struct btree *b, struct closure *parent);
+void bch_btree_node_write(struct btree *b, struct closure *parent);
+
+void bch_btree_set_root(struct btree *b);
+struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
+				     int level, bool wait,
+				     struct btree *parent);
+struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op,
+				 struct bkey *k, int level, bool write,
+				 struct btree *parent);
+
+int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
+			       struct bkey *check_key);
+int bch_btree_insert(struct cache_set *c, struct keylist *keys,
+		     atomic_t *journal_ref, struct bkey *replace_key);
+
+int bch_gc_thread_start(struct cache_set *c);
+void bch_initial_gc_finish(struct cache_set *c);
+void bch_moving_gc(struct cache_set *c);
+int bch_btree_check(struct cache_set *c);
+void bch_initial_mark_key(struct cache_set *c, int level, struct bkey *k);
+void bch_cannibalize_unlock(struct cache_set *c);
+
+static inline void wake_up_gc(struct cache_set *c)
+{
+	wake_up(&c->gc_wait);
+}
+
+static inline void force_wake_up_gc(struct cache_set *c)
+{
+	/*
+	 * Garbage collection thread only works when sectors_to_gc < 0,
+	 * calling wake_up_gc() won't start gc thread if sectors_to_gc is
+	 * not a nagetive value.
+	 * Therefore sectors_to_gc is set to -1 here, before waking up
+	 * gc thread by calling wake_up_gc(). Then gc_should_run() will
+	 * give a chance to permit gc thread to run. "Give a chance" means
+	 * before going into gc_should_run(), there is still possibility
+	 * that c->sectors_to_gc being set to other positive value. So
+	 * this routine won't 100% make sure gc thread will be woken up
+	 * to run.
+	 */
+	atomic_set(&c->sectors_to_gc, -1);
+	wake_up_gc(c);
+}
+
+/*
+ * These macros are for recursing down the btree - they handle the details of
+ * locking and looking up nodes in the cache for you. They're best treated as
+ * mere syntax when reading code that uses them.
+ *
+ * op->lock determines whether we take a read or a write lock at a given depth.
+ * If you've got a read lock and find that you need a write lock (i.e. you're
+ * going to have to split), set op->lock and return -EINTR; btree_root() will
+ * call you again and you'll have the correct lock.
+ */
+
+/**
+ * btree - recurse down the btree on a specified key
+ * @fn:		function to call, which will be passed the child node
+ * @key:	key to recurse on
+ * @b:		parent btree node
+ * @op:		pointer to struct btree_op
+ */
+#define bcache_btree(fn, key, b, op, ...)				\
+({									\
+	int _r, l = (b)->level - 1;					\
+	bool _w = l <= (op)->lock;					\
+	struct btree *_child = bch_btree_node_get((b)->c, op, key, l,	\
+						  _w, b);		\
+	if (!IS_ERR(_child)) {						\
+		_r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__);	\
+		rw_unlock(_w, _child);					\
+	} else								\
+		_r = PTR_ERR(_child);					\
+	_r;								\
+})
+
+/**
+ * btree_root - call a function on the root of the btree
+ * @fn:		function to call, which will be passed the child node
+ * @c:		cache set
+ * @op:		pointer to struct btree_op
+ */
+#define bcache_btree_root(fn, c, op, ...)				\
+({									\
+	int _r = -EINTR;						\
+	do {								\
+		struct btree *_b = (c)->root;				\
+		bool _w = insert_lock(op, _b);				\
+		rw_lock(_w, _b, _b->level);				\
+		if (_b == (c)->root &&					\
+		    _w == insert_lock(op, _b)) {			\
+			_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__);	\
+		}							\
+		rw_unlock(_w, _b);					\
+		bch_cannibalize_unlock(c);                              \
+		if (_r == -EINTR)                                       \
+			schedule();                                     \
+	} while (_r == -EINTR);                                         \
+									\
+	finish_wait(&(c)->btree_cache_wait, &(op)->wait);               \
+	_r;                                                             \
+})
+
+#define MAP_DONE	0
+#define MAP_CONTINUE	1
+
+#define MAP_ALL_NODES	0
+#define MAP_LEAF_NODES	1
+
+#define MAP_END_KEY	1
+
+typedef int (btree_map_nodes_fn)(struct btree_op *b_op, struct btree *b);
+int __bch_btree_map_nodes(struct btree_op *op, struct cache_set *c,
+			  struct bkey *from, btree_map_nodes_fn *fn, int flags);
+
+static inline int bch_btree_map_nodes(struct btree_op *op, struct cache_set *c,
+				      struct bkey *from, btree_map_nodes_fn *fn)
+{
+	return __bch_btree_map_nodes(op, c, from, fn, MAP_ALL_NODES);
+}
+
+static inline int bch_btree_map_leaf_nodes(struct btree_op *op,
+					   struct cache_set *c,
+					   struct bkey *from,
+					   btree_map_nodes_fn *fn)
+{
+	return __bch_btree_map_nodes(op, c, from, fn, MAP_LEAF_NODES);
+}
+
+typedef int (btree_map_keys_fn)(struct btree_op *op, struct btree *b,
+				struct bkey *k);
+int bch_btree_map_keys(struct btree_op *op, struct cache_set *c,
+		       struct bkey *from, btree_map_keys_fn *fn, int flags);
+int bch_btree_map_keys_recurse(struct btree *b, struct btree_op *op,
+			       struct bkey *from, btree_map_keys_fn *fn,
+			       int flags);
+
+typedef bool (keybuf_pred_fn)(struct keybuf *buf, struct bkey *k);
+
+void bch_keybuf_init(struct keybuf *buf);
+void bch_refill_keybuf(struct cache_set *c, struct keybuf *buf,
+		       struct bkey *end, keybuf_pred_fn *pred);
+bool bch_keybuf_check_overlapping(struct keybuf *buf, struct bkey *start,
+				  struct bkey *end);
+void bch_keybuf_del(struct keybuf *buf, struct keybuf_key *w);
+struct keybuf_key *bch_keybuf_next(struct keybuf *buf);
+struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
+					  struct keybuf *buf,
+					  struct bkey *end,
+					  keybuf_pred_fn *pred);
+void bch_update_bucket_in_use(struct cache_set *c, struct gc_stat *stats);
+#endif

linux-7.2.3/drivers/md/bcache/debug.c

@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Assorted bcache debug code
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "extents.h"
+
+#include <linux/console.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/seq_file.h>
+
+struct dentry *bcache_debug;
+
+#ifdef CONFIG_BCACHE_DEBUG
+
+#define for_each_written_bset(b, start, i)				\
+	for (i = (start);						\
+	     (void *) i < (void *) (start) + (KEY_SIZE(&b->key) << 9) &&\
+	     i->seq == (start)->seq;					\
+	     i = (void *) i + set_blocks(i, block_bytes(b->c->cache)) *	\
+		 block_bytes(b->c->cache))
+
+void bch_btree_verify(struct btree *b)
+{
+	struct btree *v = b->c->verify_data;
+	struct bset *ondisk, *sorted, *inmemory;
+	struct bio *bio;
+
+	if (!b->c->verify || !b->c->verify_ondisk)
+		return;
+
+	down(&b->io_mutex);
+	mutex_lock(&b->c->verify_lock);
+
+	ondisk = b->c->verify_ondisk;
+	sorted = b->c->verify_data->keys.set->data;
+	inmemory = b->keys.set->data;
+
+	bkey_copy(&v->key, &b->key);
+	v->written = 0;
+	v->level = b->level;
+	v->keys.ops = b->keys.ops;
+
+	bio = bch_bbio_alloc(b->c);
+	bio_set_dev(bio, b->c->cache->bdev);
+	bio->bi_iter.bi_sector	= PTR_OFFSET(&b->key, 0);
+	bio->bi_iter.bi_size	= KEY_SIZE(&v->key) << 9;
+	bio->bi_opf		= REQ_OP_READ | REQ_META;
+	bch_bio_map(bio, sorted);
+
+	submit_bio_wait(bio);
+	bch_bbio_free(bio, b->c);
+
+	memcpy(ondisk, sorted, KEY_SIZE(&v->key) << 9);
+
+	bch_btree_node_read_done(v);
+	sorted = v->keys.set->data;
+
+	if (inmemory->keys != sorted->keys ||
+	    memcmp(inmemory->start,
+		   sorted->start,
+		   (void *) bset_bkey_last(inmemory) -
+		   (void *) inmemory->start)) {
+		struct bset *i;
+		unsigned int j;
+
+		console_lock();
+
+		pr_err("*** in memory:\n");
+		bch_dump_bset(&b->keys, inmemory, 0);
+
+		pr_err("*** read back in:\n");
+		bch_dump_bset(&v->keys, sorted, 0);
+
+		for_each_written_bset(b, ondisk, i) {
+			unsigned int block = ((void *) i - (void *) ondisk) /
+				block_bytes(b->c->cache);
+
+			pr_err("*** on disk block %u:\n", block);
+			bch_dump_bset(&b->keys, i, block);
+		}
+
+		pr_err("*** block %zu not written\n",
+		       ((void *) i - (void *) ondisk) / block_bytes(b->c->cache));
+
+		for (j = 0; j < inmemory->keys; j++)
+			if (inmemory->d[j] != sorted->d[j])
+				break;
+
+		pr_err("b->written %u\n", b->written);
+
+		console_unlock();
+		panic("verify failed at %u\n", j);
+	}
+
+	mutex_unlock(&b->c->verify_lock);
+	up(&b->io_mutex);
+}
+
+void bch_data_verify(struct cached_dev *dc, struct bio *bio)
+{
+	unsigned int nr_segs = bio_segments(bio);
+	struct bio *check;
+	struct bio_vec bv, cbv;
+	struct bvec_iter iter, citer = { 0 };
+
+	check = bio_kmalloc(nr_segs, GFP_NOIO);
+	if (!check)
+		return;
+	bio_init_inline(check, bio->bi_bdev, nr_segs, REQ_OP_READ);
+	check->bi_iter.bi_sector = bio->bi_iter.bi_sector;
+	check->bi_iter.bi_size = bio->bi_iter.bi_size;
+
+	bch_bio_map(check, NULL);
+	if (bch_bio_alloc_pages(check, GFP_NOIO))
+		goto out_put;
+
+	submit_bio_wait(check);
+
+	citer.bi_size = UINT_MAX;
+	bio_for_each_segment(bv, bio, iter) {
+		void *p1 = bvec_kmap_local(&bv);
+		void *p2;
+
+		cbv = bio_iter_iovec(check, citer);
+		p2 = bvec_kmap_local(&cbv);
+
+		cache_set_err_on(memcmp(p1, p2, bv.bv_len),
+				 dc->disk.c,
+				 "verify failed at dev %pg sector %llu",
+				 dc->bdev,
+				 (uint64_t) bio->bi_iter.bi_sector);
+
+		kunmap_local(p2);
+		kunmap_local(p1);
+		bio_advance_iter(check, &citer, bv.bv_len);
+	}
+
+	bio_free_pages(check);
+out_put:
+	bio_uninit(check);
+	kfree(check);
+}
+
+#endif
+
+#ifdef CONFIG_DEBUG_FS
+
+/* XXX: cache set refcounting */
+
+struct dump_iterator {
+	char			buf[PAGE_SIZE];
+	size_t			bytes;
+	struct cache_set	*c;
+	struct keybuf		keys;
+};
+
+static bool dump_pred(struct keybuf *buf, struct bkey *k)
+{
+	return true;
+}
+
+static ssize_t bch_dump_read(struct file *file, char __user *buf,
+			     size_t size, loff_t *ppos)
+{
+	struct dump_iterator *i = file->private_data;
+	ssize_t ret = 0;
+	char kbuf[80];
+
+	while (size) {
+		struct keybuf_key *w;
+		unsigned int bytes = min(i->bytes, size);
+
+		if (copy_to_user(buf, i->buf, bytes))
+			return -EFAULT;
+
+		ret	 += bytes;
+		buf	 += bytes;
+		size	 -= bytes;
+		i->bytes -= bytes;
+		memmove(i->buf, i->buf + bytes, i->bytes);
+
+		if (i->bytes)
+			break;
+
+		w = bch_keybuf_next_rescan(i->c, &i->keys, &MAX_KEY, dump_pred);
+		if (!w)
+			break;
+
+		bch_extent_to_text(kbuf, sizeof(kbuf), &w->key);
+		i->bytes = snprintf(i->buf, PAGE_SIZE, "%s\n", kbuf);
+		bch_keybuf_del(&i->keys, w);
+	}
+
+	return ret;
+}
+
+static int bch_dump_open(struct inode *inode, struct file *file)
+{
+	struct cache_set *c = inode->i_private;
+	struct dump_iterator *i;
+
+	i = kzalloc_obj(struct dump_iterator);
+	if (!i)
+		return -ENOMEM;
+
+	file->private_data = i;
+	i->c = c;
+	bch_keybuf_init(&i->keys);
+	i->keys.last_scanned = KEY(0, 0, 0);
+
+	return 0;
+}
+
+static int bch_dump_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static const struct file_operations cache_set_debug_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch_dump_open,
+	.read		= bch_dump_read,
+	.release	= bch_dump_release
+};
+
+void bch_debug_init_cache_set(struct cache_set *c)
+{
+	if (!IS_ERR_OR_NULL(bcache_debug)) {
+		char name[50];
+
+		snprintf(name, 50, "bcache-%pU", c->set_uuid);
+		c->debug = debugfs_create_file(name, 0400, bcache_debug, c,
+					       &cache_set_debug_ops);
+	}
+}
+
+#endif
+
+void bch_debug_exit(void)
+{
+	debugfs_remove_recursive(bcache_debug);
+}
+
+void __init bch_debug_init(void)
+{
+	/*
+	 * it is unnecessary to check return value of
+	 * debugfs_create_file(), we should not care
+	 * about this.
+	 */
+	bcache_debug = debugfs_create_dir("bcache", NULL);
+}

linux-7.2.3/drivers/md/bcache/debug.h

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_DEBUG_H
+#define _BCACHE_DEBUG_H
+
+struct bio;
+struct cached_dev;
+struct cache_set;
+
+#ifdef CONFIG_BCACHE_DEBUG
+
+void bch_btree_verify(struct btree *b);
+void bch_data_verify(struct cached_dev *dc, struct bio *bio);
+
+#define expensive_debug_checks(c)	((c)->expensive_debug_checks)
+#define key_merging_disabled(c)		((c)->key_merging_disabled)
+#define bypass_torture_test(d)		((d)->bypass_torture_test)
+
+#else /* DEBUG */
+
+static inline void bch_btree_verify(struct btree *b) {}
+static inline void bch_data_verify(struct cached_dev *dc, struct bio *bio) {}
+
+#define expensive_debug_checks(c)	0
+#define key_merging_disabled(c)		0
+#define bypass_torture_test(d)		0
+
+#endif
+
+#ifdef CONFIG_DEBUG_FS
+void bch_debug_init_cache_set(struct cache_set *c);
+#else
+static inline void bch_debug_init_cache_set(struct cache_set *c) {}
+#endif
+
+#endif

linux-7.2.3/drivers/md/bcache/extents.c

@@ -0,0 +1,630 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
+ *
+ * Uses a block device as cache for other block devices; optimized for SSDs.
+ * All allocation is done in buckets, which should match the erase block size
+ * of the device.
+ *
+ * Buckets containing cached data are kept on a heap sorted by priority;
+ * bucket priority is increased on cache hit, and periodically all the buckets
+ * on the heap have their priority scaled down. This currently is just used as
+ * an LRU but in the future should allow for more intelligent heuristics.
+ *
+ * Buckets have an 8 bit counter; freeing is accomplished by incrementing the
+ * counter. Garbage collection is used to remove stale pointers.
+ *
+ * Indexing is done via a btree; nodes are not necessarily fully sorted, rather
+ * as keys are inserted we only sort the pages that have not yet been written.
+ * When garbage collection is run, we resort the entire node.
+ *
+ * All configuration is done via sysfs; see Documentation/admin-guide/bcache.rst.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "extents.h"
+#include "writeback.h"
+
+static void sort_key_next(struct btree_iter *iter,
+			  struct btree_iter_set *i)
+{
+	i->k = bkey_next(i->k);
+
+	if (i->k == i->end)
+		*i = iter->data[--iter->used];
+}
+
+static bool bch_key_sort_cmp(struct btree_iter_set l,
+			     struct btree_iter_set r)
+{
+	int64_t c = bkey_cmp(l.k, r.k);
+
+	return c ? c > 0 : l.k < r.k;
+}
+
+static bool __ptr_invalid(struct cache_set *c, const struct bkey *k)
+{
+	unsigned int i;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (ptr_available(c, k, i)) {
+			struct cache *ca = c->cache;
+			size_t bucket = PTR_BUCKET_NR(c, k, i);
+			size_t r = bucket_remainder(c, PTR_OFFSET(k, i));
+
+			if (KEY_SIZE(k) + r > c->cache->sb.bucket_size ||
+			    bucket <  ca->sb.first_bucket ||
+			    bucket >= ca->sb.nbuckets)
+				return true;
+		}
+
+	return false;
+}
+
+/* Common among btree and extent ptrs */
+
+static const char *bch_ptr_status(struct cache_set *c, const struct bkey *k)
+{
+	unsigned int i;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (ptr_available(c, k, i)) {
+			struct cache *ca = c->cache;
+			size_t bucket = PTR_BUCKET_NR(c, k, i);
+			size_t r = bucket_remainder(c, PTR_OFFSET(k, i));
+
+			if (KEY_SIZE(k) + r > c->cache->sb.bucket_size)
+				return "bad, length too big";
+			if (bucket <  ca->sb.first_bucket)
+				return "bad, short offset";
+			if (bucket >= ca->sb.nbuckets)
+				return "bad, offset past end of device";
+			if (ptr_stale(c, k, i))
+				return "stale";
+		}
+
+	if (!bkey_cmp(k, &ZERO_KEY))
+		return "bad, null key";
+	if (!KEY_PTRS(k))
+		return "bad, no pointers";
+	if (!KEY_SIZE(k))
+		return "zeroed key";
+	return "";
+}
+
+void bch_extent_to_text(char *buf, size_t size, const struct bkey *k)
+{
+	unsigned int i = 0;
+	char *out = buf, *end = buf + size;
+
+#define p(...)	(out += scnprintf(out, end - out, __VA_ARGS__))
+
+	p("%llu:%llu len %llu -> [", KEY_INODE(k), KEY_START(k), KEY_SIZE(k));
+
+	for (i = 0; i < KEY_PTRS(k); i++) {
+		if (i)
+			p(", ");
+
+		if (PTR_DEV(k, i) == PTR_CHECK_DEV)
+			p("check dev");
+		else
+			p("%llu:%llu gen %llu", PTR_DEV(k, i),
+			  PTR_OFFSET(k, i), PTR_GEN(k, i));
+	}
+
+	p("]");
+
+	if (KEY_DIRTY(k))
+		p(" dirty");
+	if (KEY_CSUM(k))
+		p(" cs%llu %llx", KEY_CSUM(k), k->ptr[1]);
+#undef p
+}
+
+static void bch_bkey_dump(struct btree_keys *keys, const struct bkey *k)
+{
+	struct btree *b = container_of(keys, struct btree, keys);
+	unsigned int j;
+	char buf[80];
+
+	bch_extent_to_text(buf, sizeof(buf), k);
+	pr_cont(" %s", buf);
+
+	for (j = 0; j < KEY_PTRS(k); j++) {
+		size_t n = PTR_BUCKET_NR(b->c, k, j);
+
+		pr_cont(" bucket %zu", n);
+		if (n >= b->c->cache->sb.first_bucket && n < b->c->cache->sb.nbuckets)
+			pr_cont(" prio %i",
+				PTR_BUCKET(b->c, k, j)->prio);
+	}
+
+	pr_cont(" %s\n", bch_ptr_status(b->c, k));
+}
+
+/* Btree ptrs */
+
+bool __bch_btree_ptr_invalid(struct cache_set *c, const struct bkey *k)
+{
+	char buf[80];
+
+	if (!KEY_PTRS(k) || !KEY_SIZE(k) || KEY_DIRTY(k))
+		goto bad;
+
+	if (__ptr_invalid(c, k))
+		goto bad;
+
+	return false;
+bad:
+	bch_extent_to_text(buf, sizeof(buf), k);
+	cache_bug(c, "spotted btree ptr %s: %s", buf, bch_ptr_status(c, k));
+	return true;
+}
+
+static bool bch_btree_ptr_invalid(struct btree_keys *bk, const struct bkey *k)
+{
+	struct btree *b = container_of(bk, struct btree, keys);
+
+	return __bch_btree_ptr_invalid(b->c, k);
+}
+
+static bool btree_ptr_bad_expensive(struct btree *b, const struct bkey *k)
+{
+	unsigned int i;
+	char buf[80];
+	struct bucket *g;
+
+	if (mutex_trylock(&b->c->bucket_lock)) {
+		for (i = 0; i < KEY_PTRS(k); i++)
+			if (ptr_available(b->c, k, i)) {
+				g = PTR_BUCKET(b->c, k, i);
+
+				if (KEY_DIRTY(k) ||
+				    g->prio != BTREE_PRIO ||
+				    (b->c->gc_mark_valid &&
+				     GC_MARK(g) != GC_MARK_METADATA))
+					goto err;
+			}
+
+		mutex_unlock(&b->c->bucket_lock);
+	}
+
+	return false;
+err:
+	mutex_unlock(&b->c->bucket_lock);
+	bch_extent_to_text(buf, sizeof(buf), k);
+	btree_bug(b,
+"inconsistent btree pointer %s: bucket %zi pin %i prio %i gen %i last_gc %i mark %llu",
+		  buf, PTR_BUCKET_NR(b->c, k, i), atomic_read(&g->pin),
+		  g->prio, g->gen, g->last_gc, GC_MARK(g));
+	return true;
+}
+
+static bool bch_btree_ptr_bad(struct btree_keys *bk, const struct bkey *k)
+{
+	struct btree *b = container_of(bk, struct btree, keys);
+	unsigned int i;
+
+	if (!bkey_cmp(k, &ZERO_KEY) ||
+	    !KEY_PTRS(k) ||
+	    bch_ptr_invalid(bk, k))
+		return true;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (!ptr_available(b->c, k, i) ||
+		    ptr_stale(b->c, k, i))
+			return true;
+
+	if (expensive_debug_checks(b->c) &&
+	    btree_ptr_bad_expensive(b, k))
+		return true;
+
+	return false;
+}
+
+static bool bch_btree_ptr_insert_fixup(struct btree_keys *bk,
+				       struct bkey *insert,
+				       struct btree_iter *iter,
+				       struct bkey *replace_key)
+{
+	struct btree *b = container_of(bk, struct btree, keys);
+
+	if (!KEY_OFFSET(insert))
+		btree_current_write(b)->prio_blocked++;
+
+	return false;
+}
+
+const struct btree_keys_ops bch_btree_keys_ops = {
+	.sort_cmp	= bch_key_sort_cmp,
+	.insert_fixup	= bch_btree_ptr_insert_fixup,
+	.key_invalid	= bch_btree_ptr_invalid,
+	.key_bad	= bch_btree_ptr_bad,
+	.key_to_text	= bch_extent_to_text,
+	.key_dump	= bch_bkey_dump,
+};
+
+/* Extents */
+
+/*
+ * Returns true if l > r - unless l == r, in which case returns true if l is
+ * older than r.
+ *
+ * Necessary for btree_sort_fixup() - if there are multiple keys that compare
+ * equal in different sets, we have to process them newest to oldest.
+ */
+static bool bch_extent_sort_cmp(struct btree_iter_set l,
+				struct btree_iter_set r)
+{
+	int64_t c = bkey_cmp(&START_KEY(l.k), &START_KEY(r.k));
+
+	return c ? c > 0 : l.k < r.k;
+}
+
+static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter,
+					  struct bkey *tmp)
+{
+	while (iter->used > 1) {
+		struct btree_iter_set *top = iter->data, *i = top + 1;
+
+		if (iter->used > 2 &&
+		    bch_extent_sort_cmp(i[0], i[1]))
+			i++;
+
+		if (bkey_cmp(top->k, &START_KEY(i->k)) <= 0)
+			break;
+
+		if (!KEY_SIZE(i->k)) {
+			sort_key_next(iter, i);
+			heap_sift(iter, i - top, bch_extent_sort_cmp);
+			continue;
+		}
+
+		if (top->k > i->k) {
+			if (bkey_cmp(top->k, i->k) >= 0)
+				sort_key_next(iter, i);
+			else
+				bch_cut_front(top->k, i->k);
+
+			heap_sift(iter, i - top, bch_extent_sort_cmp);
+		} else {
+			/* can't happen because of comparison func */
+			BUG_ON(!bkey_cmp(&START_KEY(top->k), &START_KEY(i->k)));
+
+			if (bkey_cmp(i->k, top->k) < 0) {
+				bkey_copy(tmp, top->k);
+
+				bch_cut_back(&START_KEY(i->k), tmp);
+				bch_cut_front(i->k, top->k);
+				heap_sift(iter, 0, bch_extent_sort_cmp);
+
+				return tmp;
+			} else {
+				bch_cut_back(&START_KEY(i->k), top->k);
+			}
+		}
+	}
+
+	return NULL;
+}
+
+static void bch_subtract_dirty(struct bkey *k,
+			   struct cache_set *c,
+			   uint64_t offset,
+			   int sectors)
+{
+	if (KEY_DIRTY(k))
+		bcache_dev_sectors_dirty_add(c, KEY_INODE(k),
+					     offset, -sectors);
+}
+
+static bool bch_extent_insert_fixup(struct btree_keys *b,
+				    struct bkey *insert,
+				    struct btree_iter *iter,
+				    struct bkey *replace_key)
+{
+	struct cache_set *c = container_of(b, struct btree, keys)->c;
+
+	uint64_t old_offset;
+	unsigned int old_size, sectors_found = 0;
+
+	BUG_ON(!KEY_OFFSET(insert));
+	BUG_ON(!KEY_SIZE(insert));
+
+	while (1) {
+		struct bkey *k = bch_btree_iter_next(iter);
+
+		if (!k)
+			break;
+
+		if (bkey_cmp(&START_KEY(k), insert) >= 0) {
+			if (KEY_SIZE(k))
+				break;
+			else
+				continue;
+		}
+
+		if (bkey_cmp(k, &START_KEY(insert)) <= 0)
+			continue;
+
+		old_offset = KEY_START(k);
+		old_size = KEY_SIZE(k);
+
+		/*
+		 * We might overlap with 0 size extents; we can't skip these
+		 * because if they're in the set we're inserting to we have to
+		 * adjust them so they don't overlap with the key we're
+		 * inserting. But we don't want to check them for replace
+		 * operations.
+		 */
+
+		if (replace_key && KEY_SIZE(k)) {
+			/*
+			 * k might have been split since we inserted/found the
+			 * key we're replacing
+			 */
+			unsigned int i;
+			uint64_t offset = KEY_START(k) -
+				KEY_START(replace_key);
+
+			/* But it must be a subset of the replace key */
+			if (KEY_START(k) < KEY_START(replace_key) ||
+			    KEY_OFFSET(k) > KEY_OFFSET(replace_key))
+				goto check_failed;
+
+			/* We didn't find a key that we were supposed to */
+			if (KEY_START(k) > KEY_START(insert) + sectors_found)
+				goto check_failed;
+
+			if (!bch_bkey_equal_header(k, replace_key))
+				goto check_failed;
+
+			/* skip past gen */
+			offset <<= 8;
+
+			BUG_ON(!KEY_PTRS(replace_key));
+
+			for (i = 0; i < KEY_PTRS(replace_key); i++)
+				if (k->ptr[i] != replace_key->ptr[i] + offset)
+					goto check_failed;
+
+			sectors_found = KEY_OFFSET(k) - KEY_START(insert);
+		}
+
+		if (bkey_cmp(insert, k) < 0 &&
+		    bkey_cmp(&START_KEY(insert), &START_KEY(k)) > 0) {
+			/*
+			 * We overlapped in the middle of an existing key: that
+			 * means we have to split the old key. But we have to do
+			 * slightly different things depending on whether the
+			 * old key has been written out yet.
+			 */
+
+			struct bkey *top;
+
+			bch_subtract_dirty(k, c, KEY_START(insert),
+				       KEY_SIZE(insert));
+
+			if (bkey_written(b, k)) {
+				/*
+				 * We insert a new key to cover the top of the
+				 * old key, and the old key is modified in place
+				 * to represent the bottom split.
+				 *
+				 * It's completely arbitrary whether the new key
+				 * is the top or the bottom, but it has to match
+				 * up with what btree_sort_fixup() does - it
+				 * doesn't check for this kind of overlap, it
+				 * depends on us inserting a new key for the top
+				 * here.
+				 */
+				top = bch_bset_search(b, bset_tree_last(b),
+						      insert);
+				bch_bset_insert(b, top, k);
+			} else {
+				BKEY_PADDED(key) temp;
+				bkey_copy(&temp.key, k);
+				bch_bset_insert(b, k, &temp.key);
+				top = bkey_next(k);
+			}
+
+			bch_cut_front(insert, top);
+			bch_cut_back(&START_KEY(insert), k);
+			bch_bset_fix_invalidated_key(b, k);
+			goto out;
+		}
+
+		if (bkey_cmp(insert, k) < 0) {
+			bch_cut_front(insert, k);
+		} else {
+			if (bkey_cmp(&START_KEY(insert), &START_KEY(k)) > 0)
+				old_offset = KEY_START(insert);
+
+			if (bkey_written(b, k) &&
+			    bkey_cmp(&START_KEY(insert), &START_KEY(k)) <= 0) {
+				/*
+				 * Completely overwrote, so we don't have to
+				 * invalidate the binary search tree
+				 */
+				bch_cut_front(k, k);
+			} else {
+				__bch_cut_back(&START_KEY(insert), k);
+				bch_bset_fix_invalidated_key(b, k);
+			}
+		}
+
+		bch_subtract_dirty(k, c, old_offset, old_size - KEY_SIZE(k));
+	}
+
+check_failed:
+	if (replace_key) {
+		if (!sectors_found) {
+			return true;
+		} else if (sectors_found < KEY_SIZE(insert)) {
+			SET_KEY_OFFSET(insert, KEY_OFFSET(insert) -
+				       (KEY_SIZE(insert) - sectors_found));
+			SET_KEY_SIZE(insert, sectors_found);
+		}
+	}
+out:
+	if (KEY_DIRTY(insert))
+		bcache_dev_sectors_dirty_add(c, KEY_INODE(insert),
+					     KEY_START(insert),
+					     KEY_SIZE(insert));
+
+	return false;
+}
+
+bool __bch_extent_invalid(struct cache_set *c, const struct bkey *k)
+{
+	char buf[80];
+
+	if (!KEY_SIZE(k))
+		return true;
+
+	if (KEY_SIZE(k) > KEY_OFFSET(k))
+		goto bad;
+
+	if (__ptr_invalid(c, k))
+		goto bad;
+
+	return false;
+bad:
+	bch_extent_to_text(buf, sizeof(buf), k);
+	cache_bug(c, "spotted extent %s: %s", buf, bch_ptr_status(c, k));
+	return true;
+}
+
+static bool bch_extent_invalid(struct btree_keys *bk, const struct bkey *k)
+{
+	struct btree *b = container_of(bk, struct btree, keys);
+
+	return __bch_extent_invalid(b->c, k);
+}
+
+static bool bch_extent_bad_expensive(struct btree *b, const struct bkey *k,
+				     unsigned int ptr)
+{
+	struct bucket *g = PTR_BUCKET(b->c, k, ptr);
+	char buf[80];
+
+	if (mutex_trylock(&b->c->bucket_lock)) {
+		if (b->c->gc_mark_valid &&
+		    (!GC_MARK(g) ||
+		     GC_MARK(g) == GC_MARK_METADATA ||
+		     (GC_MARK(g) != GC_MARK_DIRTY && KEY_DIRTY(k))))
+			goto err;
+
+		if (g->prio == BTREE_PRIO)
+			goto err;
+
+		mutex_unlock(&b->c->bucket_lock);
+	}
+
+	return false;
+err:
+	mutex_unlock(&b->c->bucket_lock);
+	bch_extent_to_text(buf, sizeof(buf), k);
+	btree_bug(b,
+"inconsistent extent pointer %s:\nbucket %zu pin %i prio %i gen %i last_gc %i mark %llu",
+		  buf, PTR_BUCKET_NR(b->c, k, ptr), atomic_read(&g->pin),
+		  g->prio, g->gen, g->last_gc, GC_MARK(g));
+	return true;
+}
+
+static bool bch_extent_bad(struct btree_keys *bk, const struct bkey *k)
+{
+	struct btree *b = container_of(bk, struct btree, keys);
+	unsigned int i, stale;
+	char buf[80];
+
+	if (!KEY_PTRS(k) ||
+	    bch_extent_invalid(bk, k))
+		return true;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (!ptr_available(b->c, k, i))
+			return true;
+
+	for (i = 0; i < KEY_PTRS(k); i++) {
+		stale = ptr_stale(b->c, k, i);
+
+		if (stale && KEY_DIRTY(k)) {
+			bch_extent_to_text(buf, sizeof(buf), k);
+			pr_info("stale dirty pointer, stale %u, key: %s\n",
+				stale, buf);
+		}
+
+		btree_bug_on(stale > BUCKET_GC_GEN_MAX, b,
+			     "key too stale: %i, need_gc %u",
+			     stale, b->c->need_gc);
+
+		if (stale)
+			return true;
+
+		if (expensive_debug_checks(b->c) &&
+		    bch_extent_bad_expensive(b, k, i))
+			return true;
+	}
+
+	return false;
+}
+
+static uint64_t merge_chksums(struct bkey *l, struct bkey *r)
+{
+	return (l->ptr[KEY_PTRS(l)] + r->ptr[KEY_PTRS(r)]) &
+		~((uint64_t)1 << 63);
+}
+
+static bool bch_extent_merge(struct btree_keys *bk,
+			     struct bkey *l,
+			     struct bkey *r)
+{
+	struct btree *b = container_of(bk, struct btree, keys);
+	unsigned int i;
+
+	if (key_merging_disabled(b->c))
+		return false;
+
+	for (i = 0; i < KEY_PTRS(l); i++)
+		if (l->ptr[i] + MAKE_PTR(0, KEY_SIZE(l), 0) != r->ptr[i] ||
+		    PTR_BUCKET_NR(b->c, l, i) != PTR_BUCKET_NR(b->c, r, i))
+			return false;
+
+	/* Keys with no pointers aren't restricted to one bucket and could
+	 * overflow KEY_SIZE
+	 */
+	if (KEY_SIZE(l) + KEY_SIZE(r) > USHRT_MAX) {
+		SET_KEY_OFFSET(l, KEY_OFFSET(l) + USHRT_MAX - KEY_SIZE(l));
+		SET_KEY_SIZE(l, USHRT_MAX);
+
+		bch_cut_front(l, r);
+		return false;
+	}
+
+	if (KEY_CSUM(l)) {
+		if (KEY_CSUM(r))
+			l->ptr[KEY_PTRS(l)] = merge_chksums(l, r);
+		else
+			SET_KEY_CSUM(l, 0);
+	}
+
+	SET_KEY_OFFSET(l, KEY_OFFSET(l) + KEY_SIZE(r));
+	SET_KEY_SIZE(l, KEY_SIZE(l) + KEY_SIZE(r));
+
+	return true;
+}
+
+const struct btree_keys_ops bch_extent_keys_ops = {
+	.sort_cmp	= bch_extent_sort_cmp,
+	.sort_fixup	= bch_extent_sort_fixup,
+	.insert_fixup	= bch_extent_insert_fixup,
+	.key_invalid	= bch_extent_invalid,
+	.key_bad	= bch_extent_bad,
+	.key_merge	= bch_extent_merge,
+	.key_to_text	= bch_extent_to_text,
+	.key_dump	= bch_bkey_dump,
+	.is_extents	= true,
+};

linux-7.2.3/drivers/md/bcache/extents.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_EXTENTS_H
+#define _BCACHE_EXTENTS_H
+
+extern const struct btree_keys_ops bch_btree_keys_ops;
+extern const struct btree_keys_ops bch_extent_keys_ops;
+
+struct bkey;
+struct cache_set;
+
+void bch_extent_to_text(char *buf, size_t size, const struct bkey *k);
+bool __bch_btree_ptr_invalid(struct cache_set *c, const struct bkey *k);
+bool __bch_extent_invalid(struct cache_set *c, const struct bkey *k);
+
+#endif /* _BCACHE_EXTENTS_H */

linux-7.2.3/drivers/md/bcache/features.c

@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Feature set bits and string conversion.
+ * Inspired by ext4's features compat/incompat/ro_compat related code.
+ *
+ * Copyright 2020 Coly Li <colyli@suse.de>
+ *
+ */
+#include "bcache_ondisk.h"
+#include "bcache.h"
+#include "features.h"
+
+struct feature {
+	int		compat;
+	unsigned int	mask;
+	const char	*string;
+};
+
+static struct feature feature_list[] = {
+	{BCH_FEATURE_INCOMPAT, BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE,
+		"large_bucket"},
+	{0, 0, NULL },
+};
+
+#define compose_feature_string(type)				\
+({									\
+	struct feature *f;						\
+	bool first = true;						\
+									\
+	for (f = &feature_list[0]; f->compat != 0; f++) {		\
+		if (f->compat != BCH_FEATURE_ ## type)			\
+			continue;					\
+		if (BCH_HAS_ ## type ## _FEATURE(&c->cache->sb, f->mask)) {	\
+			if (first) {					\
+				out += snprintf(out, buf + size - out,	\
+						"[");	\
+			} else {					\
+				out += snprintf(out, buf + size - out,	\
+						" [");			\
+			}						\
+		} else if (!first) {					\
+			out += snprintf(out, buf + size - out, " ");	\
+		}							\
+									\
+		out += snprintf(out, buf + size - out, "%s", f->string);\
+									\
+		if (BCH_HAS_ ## type ## _FEATURE(&c->cache->sb, f->mask))	\
+			out += snprintf(out, buf + size - out, "]");	\
+									\
+		first = false;						\
+	}								\
+	if (!first)							\
+		out += snprintf(out, buf + size - out, "\n");		\
+})
+
+int bch_print_cache_set_feature_compat(struct cache_set *c, char *buf, int size)
+{
+	char *out = buf;
+	compose_feature_string(COMPAT);
+	return out - buf;
+}
+
+int bch_print_cache_set_feature_ro_compat(struct cache_set *c, char *buf, int size)
+{
+	char *out = buf;
+	compose_feature_string(RO_COMPAT);
+	return out - buf;
+}
+
+int bch_print_cache_set_feature_incompat(struct cache_set *c, char *buf, int size)
+{
+	char *out = buf;
+	compose_feature_string(INCOMPAT);
+	return out - buf;
+}

linux-7.2.3/drivers/md/bcache/features.h

@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _BCACHE_FEATURES_H
+#define _BCACHE_FEATURES_H
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+
+#include "bcache_ondisk.h"
+
+#define BCH_FEATURE_COMPAT		0
+#define BCH_FEATURE_RO_COMPAT		1
+#define BCH_FEATURE_INCOMPAT		2
+#define BCH_FEATURE_TYPE_MASK		0x03
+
+/* Feature set definition */
+/* Incompat feature set */
+/* 32bit bucket size, obsoleted */
+#define BCH_FEATURE_INCOMPAT_OBSO_LARGE_BUCKET		0x0001
+/* real bucket size is (1 << bucket_size) */
+#define BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE	0x0002
+
+#define BCH_FEATURE_COMPAT_SUPP		0
+#define BCH_FEATURE_RO_COMPAT_SUPP	0
+#define BCH_FEATURE_INCOMPAT_SUPP	(BCH_FEATURE_INCOMPAT_OBSO_LARGE_BUCKET| \
+					 BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE)
+
+#define BCH_HAS_COMPAT_FEATURE(sb, mask) \
+		((sb)->feature_compat & (mask))
+#define BCH_HAS_RO_COMPAT_FEATURE(sb, mask) \
+		((sb)->feature_ro_compat & (mask))
+#define BCH_HAS_INCOMPAT_FEATURE(sb, mask) \
+		((sb)->feature_incompat & (mask))
+
+#define BCH_FEATURE_COMPAT_FUNCS(name, flagname) \
+static inline int bch_has_feature_##name(struct cache_sb *sb) \
+{ \
+	if (sb->version < BCACHE_SB_VERSION_CDEV_WITH_FEATURES) \
+		return 0; \
+	return (((sb)->feature_compat & \
+		BCH##_FEATURE_COMPAT_##flagname) != 0); \
+} \
+static inline void bch_set_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_compat |= \
+		BCH##_FEATURE_COMPAT_##flagname; \
+} \
+static inline void bch_clear_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_compat &= \
+		~BCH##_FEATURE_COMPAT_##flagname; \
+}
+
+#define BCH_FEATURE_RO_COMPAT_FUNCS(name, flagname) \
+static inline int bch_has_feature_##name(struct cache_sb *sb) \
+{ \
+	if (sb->version < BCACHE_SB_VERSION_CDEV_WITH_FEATURES) \
+		return 0; \
+	return (((sb)->feature_ro_compat & \
+		BCH##_FEATURE_RO_COMPAT_##flagname) != 0); \
+} \
+static inline void bch_set_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_ro_compat |= \
+		BCH##_FEATURE_RO_COMPAT_##flagname; \
+} \
+static inline void bch_clear_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_ro_compat &= \
+		~BCH##_FEATURE_RO_COMPAT_##flagname; \
+}
+
+#define BCH_FEATURE_INCOMPAT_FUNCS(name, flagname) \
+static inline int bch_has_feature_##name(struct cache_sb *sb) \
+{ \
+	if (sb->version < BCACHE_SB_VERSION_CDEV_WITH_FEATURES) \
+		return 0; \
+	return (((sb)->feature_incompat & \
+		BCH##_FEATURE_INCOMPAT_##flagname) != 0); \
+} \
+static inline void bch_set_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_incompat |= \
+		BCH##_FEATURE_INCOMPAT_##flagname; \
+} \
+static inline void bch_clear_feature_##name(struct cache_sb *sb) \
+{ \
+	(sb)->feature_incompat &= \
+		~BCH##_FEATURE_INCOMPAT_##flagname; \
+}
+
+BCH_FEATURE_INCOMPAT_FUNCS(obso_large_bucket, OBSO_LARGE_BUCKET);
+BCH_FEATURE_INCOMPAT_FUNCS(large_bucket, LOG_LARGE_BUCKET_SIZE);
+
+static inline bool bch_has_unknown_compat_features(struct cache_sb *sb)
+{
+	return ((sb->feature_compat & ~BCH_FEATURE_COMPAT_SUPP) != 0);
+}
+
+static inline bool bch_has_unknown_ro_compat_features(struct cache_sb *sb)
+{
+	return ((sb->feature_ro_compat & ~BCH_FEATURE_RO_COMPAT_SUPP) != 0);
+}
+
+static inline bool bch_has_unknown_incompat_features(struct cache_sb *sb)
+{
+	return ((sb->feature_incompat & ~BCH_FEATURE_INCOMPAT_SUPP) != 0);
+}
+
+int bch_print_cache_set_feature_compat(struct cache_set *c, char *buf, int size);
+int bch_print_cache_set_feature_ro_compat(struct cache_set *c, char *buf, int size);
+int bch_print_cache_set_feature_incompat(struct cache_set *c, char *buf, int size);
+
+#endif

linux-7.2.3/drivers/md/bcache/io.c

@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Some low level IO code, and hacks for various block layer limitations
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "bset.h"
+#include "debug.h"
+
+#include <linux/blkdev.h>
+
+/* Bios with headers */
+
+void bch_bbio_free(struct bio *bio, struct cache_set *c)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+
+	mempool_free(b, &c->bio_meta);
+}
+
+struct bio *bch_bbio_alloc(struct cache_set *c)
+{
+	struct bbio *b = mempool_alloc(&c->bio_meta, GFP_NOIO);
+	struct bio *bio = &b->bio;
+
+	bio_init_inline(bio, NULL, meta_bucket_pages(&c->cache->sb), 0);
+
+	return bio;
+}
+
+void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+
+	bio->bi_iter.bi_sector	= PTR_OFFSET(&b->key, 0);
+	bio_set_dev(bio, c->cache->bdev);
+
+	b->submit_time_us = local_clock_us();
+	closure_bio_submit(c, bio, bio->bi_private);
+}
+
+void bch_submit_bbio(struct bio *bio, struct cache_set *c,
+		     struct bkey *k, unsigned int ptr)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+
+	bch_bkey_copy_single_ptr(&b->key, k, ptr);
+	__bch_submit_bbio(bio, c);
+}
+
+/* IO errors */
+void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
+{
+	unsigned int errors;
+
+	WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
+
+	/*
+	 * Read-ahead requests on a degrading and recovering md raid
+	 * (e.g. raid6) device might be failured immediately by md
+	 * raid code, which is not a real hardware media failure. So
+	 * we shouldn't count failed REQ_RAHEAD bio to dc->io_errors.
+	 */
+	if (bio->bi_opf & REQ_RAHEAD) {
+		pr_warn_ratelimited("%pg: Read-ahead I/O failed on backing device, ignore\n",
+				    dc->bdev);
+		return;
+	}
+
+	errors = atomic_add_return(1, &dc->io_errors);
+	if (errors < dc->error_limit)
+		pr_err("%pg: IO error on backing device, unrecoverable\n",
+			dc->bdev);
+	else
+		bch_cached_dev_error(dc);
+}
+
+void bch_count_io_errors(struct cache *ca,
+			 blk_status_t error,
+			 int is_read,
+			 const char *m)
+{
+	/*
+	 * The halflife of an error is:
+	 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
+	 */
+
+	if (ca->set->error_decay) {
+		unsigned int count = atomic_inc_return(&ca->io_count);
+
+		while (count > ca->set->error_decay) {
+			unsigned int errors;
+			unsigned int old = count;
+			unsigned int new = count - ca->set->error_decay;
+
+			/*
+			 * First we subtract refresh from count; each time we
+			 * successfully do so, we rescale the errors once:
+			 */
+
+			count = atomic_cmpxchg(&ca->io_count, old, new);
+
+			if (count == old) {
+				count = new;
+
+				errors = atomic_read(&ca->io_errors);
+				do {
+					old = errors;
+					new = ((uint64_t) errors * 127) / 128;
+					errors = atomic_cmpxchg(&ca->io_errors,
+								old, new);
+				} while (old != errors);
+			}
+		}
+	}
+
+	if (error) {
+		unsigned int errors = atomic_add_return(1 << IO_ERROR_SHIFT,
+						    &ca->io_errors);
+		errors >>= IO_ERROR_SHIFT;
+
+		if (errors < ca->set->error_limit)
+			pr_err("%pg: IO error on %s%s\n",
+			       ca->bdev, m,
+			       is_read ? ", recovering." : ".");
+		else
+			bch_cache_set_error(ca->set,
+					    "%pg: too many IO errors %s\n",
+					    ca->bdev, m);
+	}
+}
+
+void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
+			      blk_status_t error, const char *m)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+	struct cache *ca = c->cache;
+	int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
+
+	unsigned int threshold = op_is_write(bio_op(bio))
+		? c->congested_write_threshold_us
+		: c->congested_read_threshold_us;
+
+	if (threshold) {
+		unsigned int t = local_clock_us();
+		int us = t - b->submit_time_us;
+		int congested = atomic_read(&c->congested);
+
+		if (us > (int) threshold) {
+			int ms = us / 1024;
+
+			c->congested_last_us = t;
+
+			ms = min(ms, CONGESTED_MAX + congested);
+			atomic_sub(ms, &c->congested);
+		} else if (congested < 0)
+			atomic_inc(&c->congested);
+	}
+
+	bch_count_io_errors(ca, error, is_read, m);
+}
+
+void bch_bbio_endio(struct cache_set *c, struct bio *bio,
+		    blk_status_t error, const char *m)
+{
+	struct closure *cl = bio->bi_private;
+
+	bch_bbio_count_io_errors(c, bio, error, m);
+	bio_put(bio);
+	closure_put(cl);
+}

linux-7.2.3/drivers/md/bcache/journal.c

@@ -0,0 +1,923 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * bcache journalling code, for btree insertions
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "extents.h"
+
+#include <trace/events/bcache.h>
+
+/*
+ * Journal replay/recovery:
+ *
+ * This code is all driven from run_cache_set(); we first read the journal
+ * entries, do some other stuff, then we mark all the keys in the journal
+ * entries (same as garbage collection would), then we replay them - reinserting
+ * them into the cache in precisely the same order as they appear in the
+ * journal.
+ *
+ * We only journal keys that go in leaf nodes, which simplifies things quite a
+ * bit.
+ */
+
+static void journal_read_endio(struct bio *bio)
+{
+	struct closure *cl = bio->bi_private;
+
+	closure_put(cl);
+}
+
+static int journal_read_bucket(struct cache *ca, struct list_head *list,
+			       unsigned int bucket_index)
+{
+	struct journal_device *ja = &ca->journal;
+	struct bio *bio = &ja->bio;
+
+	struct journal_replay *i;
+	struct jset *j, *data = ca->set->journal.w[0].data;
+	struct closure cl;
+	unsigned int len, left, offset = 0;
+	int ret = 0;
+	sector_t bucket = bucket_to_sector(ca->set, ca->sb.d[bucket_index]);
+
+	closure_init_stack(&cl);
+
+	pr_debug("reading %u\n", bucket_index);
+
+	while (offset < ca->sb.bucket_size) {
+reread:		left = ca->sb.bucket_size - offset;
+		len = min_t(unsigned int, left, PAGE_SECTORS << JSET_BITS);
+
+		bio_reset(bio, ca->bdev, REQ_OP_READ);
+		bio->bi_iter.bi_sector	= bucket + offset;
+		bio->bi_iter.bi_size	= len << 9;
+
+		bio->bi_end_io	= journal_read_endio;
+		bio->bi_private = &cl;
+		bch_bio_map(bio, data);
+
+		closure_bio_submit(ca->set, bio, &cl);
+		closure_sync(&cl);
+
+		/* This function could be simpler now since we no longer write
+		 * journal entries that overlap bucket boundaries; this means
+		 * the start of a bucket will always have a valid journal entry
+		 * if it has any journal entries at all.
+		 */
+
+		j = data;
+		while (len) {
+			struct list_head *where;
+			size_t blocks, bytes = set_bytes(j);
+
+			if (j->magic != jset_magic(&ca->sb)) {
+				pr_debug("%u: bad magic\n", bucket_index);
+				return ret;
+			}
+
+			if (bytes > left << 9 ||
+			    bytes > PAGE_SIZE << JSET_BITS) {
+				pr_info("%u: too big, %zu bytes, offset %u\n",
+					bucket_index, bytes, offset);
+				return ret;
+			}
+
+			if (bytes > len << 9)
+				goto reread;
+
+			if (j->csum != csum_set(j)) {
+				pr_info("%u: bad csum, %zu bytes, offset %u\n",
+					bucket_index, bytes, offset);
+				return ret;
+			}
+
+			blocks = set_blocks(j, block_bytes(ca));
+
+			/*
+			 * Nodes in 'list' are in linear increasing order of
+			 * i->j.seq, the node on head has the smallest (oldest)
+			 * journal seq, the node on tail has the biggest
+			 * (latest) journal seq.
+			 */
+
+			/*
+			 * Check from the oldest jset for last_seq. If
+			 * i->j.seq < j->last_seq, it means the oldest jset
+			 * in list is expired and useless, remove it from
+			 * this list. Otherwise, j is a candidate jset for
+			 * further following checks.
+			 */
+			while (!list_empty(list)) {
+				i = list_first_entry(list,
+					struct journal_replay, list);
+				if (i->j.seq >= j->last_seq)
+					break;
+				list_del(&i->list);
+				kfree(i);
+			}
+
+			/* iterate list in reverse order (from latest jset) */
+			list_for_each_entry_reverse(i, list, list) {
+				if (j->seq == i->j.seq)
+					goto next_set;
+
+				/*
+				 * if j->seq is less than any i->j.last_seq
+				 * in list, j is an expired and useless jset.
+				 */
+				if (j->seq < i->j.last_seq)
+					goto next_set;
+
+				/*
+				 * 'where' points to first jset in list which
+				 * is elder then j.
+				 */
+				if (j->seq > i->j.seq) {
+					where = &i->list;
+					goto add;
+				}
+			}
+
+			where = list;
+add:
+			i = kmalloc(offsetof(struct journal_replay, j) +
+				    bytes, GFP_KERNEL);
+			if (!i)
+				return -ENOMEM;
+			unsafe_memcpy(&i->j, j, bytes,
+				/* "bytes" was calculated by set_bytes() above */);
+			/* Add to the location after 'where' points to */
+			list_add(&i->list, where);
+			ret = 1;
+
+			if (j->seq > ja->seq[bucket_index])
+				ja->seq[bucket_index] = j->seq;
+next_set:
+			offset	+= blocks * ca->sb.block_size;
+			len	-= blocks * ca->sb.block_size;
+			j = ((void *) j) + blocks * block_bytes(ca);
+		}
+	}
+
+	return ret;
+}
+
+int bch_journal_read(struct cache_set *c, struct list_head *list)
+{
+#define read_bucket(b)							\
+	({								\
+		ret = journal_read_bucket(ca, list, b);			\
+		__set_bit(b, bitmap);					\
+		if (ret < 0)						\
+			return ret;					\
+		ret;							\
+	})
+
+	struct cache *ca = c->cache;
+	int ret = 0;
+	struct journal_device *ja = &ca->journal;
+	DECLARE_BITMAP(bitmap, SB_JOURNAL_BUCKETS);
+	unsigned int i, l, r, m;
+	uint64_t seq;
+
+	bitmap_zero(bitmap, SB_JOURNAL_BUCKETS);
+	pr_debug("%u journal buckets\n", ca->sb.njournal_buckets);
+
+	/*
+	 * Read journal buckets ordered by golden ratio hash to quickly
+	 * find a sequence of buckets with valid journal entries
+	 */
+	for (i = 0; i < ca->sb.njournal_buckets; i++) {
+		/*
+		 * We must try the index l with ZERO first for
+		 * correctness due to the scenario that the journal
+		 * bucket is circular buffer which might have wrapped
+		 */
+		l = (i * 2654435769U) % ca->sb.njournal_buckets;
+
+		if (test_bit(l, bitmap))
+			break;
+
+		if (read_bucket(l))
+			goto bsearch;
+	}
+
+	/*
+	 * If that fails, check all the buckets we haven't checked
+	 * already
+	 */
+	pr_debug("falling back to linear search\n");
+
+	for_each_clear_bit(l, bitmap, ca->sb.njournal_buckets)
+		if (read_bucket(l))
+			goto bsearch;
+
+	/* no journal entries on this device? */
+	if (l == ca->sb.njournal_buckets)
+		goto out;
+bsearch:
+	BUG_ON(list_empty(list));
+
+	/* Binary search */
+	m = l;
+	r = find_next_bit(bitmap, ca->sb.njournal_buckets, l + 1);
+	pr_debug("starting binary search, l %u r %u\n", l, r);
+
+	while (l + 1 < r) {
+		seq = list_entry(list->prev, struct journal_replay,
+				 list)->j.seq;
+
+		m = (l + r) >> 1;
+		read_bucket(m);
+
+		if (seq != list_entry(list->prev, struct journal_replay,
+				      list)->j.seq)
+			l = m;
+		else
+			r = m;
+	}
+
+	/*
+	 * Read buckets in reverse order until we stop finding more
+	 * journal entries
+	 */
+	pr_debug("finishing up: m %u njournal_buckets %u\n",
+		 m, ca->sb.njournal_buckets);
+	l = m;
+
+	while (1) {
+		if (!l--)
+			l = ca->sb.njournal_buckets - 1;
+
+		if (l == m)
+			break;
+
+		if (test_bit(l, bitmap))
+			continue;
+
+		if (!read_bucket(l))
+			break;
+	}
+
+	seq = 0;
+
+	for (i = 0; i < ca->sb.njournal_buckets; i++)
+		if (ja->seq[i] > seq) {
+			seq = ja->seq[i];
+			/*
+			 * When journal_reclaim() goes to allocate for
+			 * the first time, it'll use the bucket after
+			 * ja->cur_idx
+			 */
+			ja->cur_idx = i;
+			ja->last_idx = (i + 1) % ca->sb.njournal_buckets;
+
+		}
+
+out:
+	if (!list_empty(list))
+		c->journal.seq = list_entry(list->prev,
+					    struct journal_replay,
+					    list)->j.seq;
+
+	return 0;
+#undef read_bucket
+}
+
+void bch_journal_mark(struct cache_set *c, struct list_head *list)
+{
+	atomic_t p = { 0 };
+	struct bkey *k;
+	struct journal_replay *i;
+	struct journal *j = &c->journal;
+	uint64_t last = j->seq;
+
+	/*
+	 * journal.pin should never fill up - we never write a journal
+	 * entry when it would fill up. But if for some reason it does, we
+	 * iterate over the list in reverse order so that we can just skip that
+	 * refcount instead of bugging.
+	 */
+
+	list_for_each_entry_reverse(i, list, list) {
+		BUG_ON(last < i->j.seq);
+		i->pin = NULL;
+
+		while (last-- != i->j.seq)
+			if (fifo_free(&j->pin) > 1) {
+				fifo_push_front(&j->pin, p);
+				atomic_set(&fifo_front(&j->pin), 0);
+			}
+
+		if (fifo_free(&j->pin) > 1) {
+			fifo_push_front(&j->pin, p);
+			i->pin = &fifo_front(&j->pin);
+			atomic_set(i->pin, 1);
+		}
+
+		for (k = i->j.start;
+		     k < bset_bkey_last(&i->j);
+		     k = bkey_next(k))
+			if (!__bch_extent_invalid(c, k)) {
+				unsigned int j;
+
+				for (j = 0; j < KEY_PTRS(k); j++)
+					if (ptr_available(c, k, j))
+						atomic_inc(&PTR_BUCKET(c, k, j)->pin);
+
+				bch_initial_mark_key(c, 0, k);
+			}
+	}
+}
+
+int bch_journal_replay(struct cache_set *s, struct list_head *list)
+{
+	int ret = 0, keys = 0, entries = 0;
+	struct bkey *k;
+	struct journal_replay *i =
+		list_entry(list->prev, struct journal_replay, list);
+
+	uint64_t start = i->j.last_seq, end = i->j.seq, n = start;
+	struct keylist keylist;
+
+	list_for_each_entry(i, list, list) {
+		BUG_ON(i->pin && atomic_read(i->pin) != 1);
+
+		if (n != i->j.seq) {
+			pr_err("journal entries %llu-%llu missing! (replaying %llu-%llu)\n",
+				n, i->j.seq - 1, start, end);
+			ret = -EIO;
+			goto err;
+		}
+
+		for (k = i->j.start;
+		     k < bset_bkey_last(&i->j);
+		     k = bkey_next(k)) {
+			trace_bcache_journal_replay_key(k);
+
+			bch_keylist_init_single(&keylist, k);
+
+			ret = bch_btree_insert(s, &keylist, i->pin, NULL);
+			if (ret)
+				goto err;
+
+			BUG_ON(!bch_keylist_empty(&keylist));
+			keys++;
+
+			cond_resched();
+		}
+
+		if (i->pin)
+			atomic_dec(i->pin);
+		n = i->j.seq + 1;
+		entries++;
+	}
+
+	pr_info("journal replay done, %i keys in %i entries, seq %llu\n",
+		keys, entries, end);
+err:
+	while (!list_empty(list)) {
+		i = list_first_entry(list, struct journal_replay, list);
+		list_del(&i->list);
+		kfree(i);
+	}
+
+	return ret;
+}
+
+void bch_journal_space_reserve(struct journal *j)
+{
+	j->do_reserve = true;
+}
+
+/* Journalling */
+
+static void btree_flush_write(struct cache_set *c)
+{
+	struct btree *b, *t, *btree_nodes[BTREE_FLUSH_NR];
+	unsigned int i, nr;
+	int ref_nr;
+	atomic_t *fifo_front_p, *now_fifo_front_p;
+	size_t mask;
+
+	if (c->journal.btree_flushing)
+		return;
+
+	spin_lock(&c->journal.flush_write_lock);
+	if (c->journal.btree_flushing) {
+		spin_unlock(&c->journal.flush_write_lock);
+		return;
+	}
+	c->journal.btree_flushing = true;
+	spin_unlock(&c->journal.flush_write_lock);
+
+	/* get the oldest journal entry and check its refcount */
+	spin_lock(&c->journal.lock);
+	fifo_front_p = &fifo_front(&c->journal.pin);
+	ref_nr = atomic_read(fifo_front_p);
+	if (ref_nr <= 0) {
+		/*
+		 * do nothing if no btree node references
+		 * the oldest journal entry
+		 */
+		spin_unlock(&c->journal.lock);
+		goto out;
+	}
+	spin_unlock(&c->journal.lock);
+
+	mask = c->journal.pin.mask;
+	nr = 0;
+	atomic_long_inc(&c->flush_write);
+	memset(btree_nodes, 0, sizeof(btree_nodes));
+
+	mutex_lock(&c->bucket_lock);
+	list_for_each_entry_safe_reverse(b, t, &c->btree_cache, list) {
+		/*
+		 * It is safe to get now_fifo_front_p without holding
+		 * c->journal.lock here, because we don't need to know
+		 * the exactly accurate value, just check whether the
+		 * front pointer of c->journal.pin is changed.
+		 */
+		now_fifo_front_p = &fifo_front(&c->journal.pin);
+		/*
+		 * If the oldest journal entry is reclaimed and front
+		 * pointer of c->journal.pin changes, it is unnecessary
+		 * to scan c->btree_cache anymore, just quit the loop and
+		 * flush out what we have already.
+		 */
+		if (now_fifo_front_p != fifo_front_p)
+			break;
+		/*
+		 * quit this loop if all matching btree nodes are
+		 * scanned and record in btree_nodes[] already.
+		 */
+		ref_nr = atomic_read(fifo_front_p);
+		if (nr >= ref_nr)
+			break;
+
+		if (btree_node_journal_flush(b))
+			pr_err("BUG: flush_write bit should not be set here!\n");
+
+		mutex_lock(&b->write_lock);
+
+		if (!btree_node_dirty(b)) {
+			mutex_unlock(&b->write_lock);
+			continue;
+		}
+
+		if (!btree_current_write(b)->journal) {
+			mutex_unlock(&b->write_lock);
+			continue;
+		}
+
+		/*
+		 * Only select the btree node which exactly references
+		 * the oldest journal entry.
+		 *
+		 * If the journal entry pointed by fifo_front_p is
+		 * reclaimed in parallel, don't worry:
+		 * - the list_for_each_xxx loop will quit when checking
+		 *   next now_fifo_front_p.
+		 * - If there are matched nodes recorded in btree_nodes[],
+		 *   they are clean now (this is why and how the oldest
+		 *   journal entry can be reclaimed). These selected nodes
+		 *   will be ignored and skipped in the following for-loop.
+		 */
+		if (((btree_current_write(b)->journal - fifo_front_p) &
+		     mask) != 0) {
+			mutex_unlock(&b->write_lock);
+			continue;
+		}
+
+		set_btree_node_journal_flush(b);
+
+		mutex_unlock(&b->write_lock);
+
+		btree_nodes[nr++] = b;
+		/*
+		 * To avoid holding c->bucket_lock too long time,
+		 * only scan for BTREE_FLUSH_NR matched btree nodes
+		 * at most. If there are more btree nodes reference
+		 * the oldest journal entry, try to flush them next
+		 * time when btree_flush_write() is called.
+		 */
+		if (nr == BTREE_FLUSH_NR)
+			break;
+	}
+	mutex_unlock(&c->bucket_lock);
+
+	for (i = 0; i < nr; i++) {
+		b = btree_nodes[i];
+		if (!b) {
+			pr_err("BUG: btree_nodes[%d] is NULL\n", i);
+			continue;
+		}
+
+		/* safe to check without holding b->write_lock */
+		if (!btree_node_journal_flush(b)) {
+			pr_err("BUG: bnode %p: journal_flush bit cleaned\n", b);
+			continue;
+		}
+
+		mutex_lock(&b->write_lock);
+		if (!btree_current_write(b)->journal) {
+			clear_bit(BTREE_NODE_journal_flush, &b->flags);
+			mutex_unlock(&b->write_lock);
+			pr_debug("bnode %p: written by others\n", b);
+			continue;
+		}
+
+		if (!btree_node_dirty(b)) {
+			clear_bit(BTREE_NODE_journal_flush, &b->flags);
+			mutex_unlock(&b->write_lock);
+			pr_debug("bnode %p: dirty bit cleaned by others\n", b);
+			continue;
+		}
+
+		__bch_btree_node_write(b, NULL);
+		clear_bit(BTREE_NODE_journal_flush, &b->flags);
+		mutex_unlock(&b->write_lock);
+	}
+
+out:
+	spin_lock(&c->journal.flush_write_lock);
+	c->journal.btree_flushing = false;
+	spin_unlock(&c->journal.flush_write_lock);
+}
+
+#define last_seq(j)	((j)->seq - fifo_used(&(j)->pin) + 1)
+
+static unsigned int free_journal_buckets(struct cache_set *c)
+{
+	struct journal *j = &c->journal;
+	struct cache *ca = c->cache;
+	struct journal_device *ja = &c->cache->journal;
+	unsigned int n;
+
+	/* In case njournal_buckets is not power of 2 */
+	if (ja->cur_idx >= ja->last_idx)
+		n = ca->sb.njournal_buckets + ja->last_idx - ja->cur_idx;
+	else
+		n = ja->last_idx - ja->cur_idx;
+
+	if (n > (1 + j->do_reserve))
+		return n - (1 + j->do_reserve);
+
+	return 0;
+}
+
+static void journal_reclaim(struct cache_set *c)
+{
+	struct bkey *k = &c->journal.key;
+	struct cache *ca = c->cache;
+	uint64_t last_seq;
+	struct journal_device *ja = &ca->journal;
+	atomic_t p __maybe_unused;
+
+	atomic_long_inc(&c->reclaim);
+
+	while (!atomic_read(&fifo_front(&c->journal.pin)))
+		fifo_pop(&c->journal.pin, p);
+
+	last_seq = last_seq(&c->journal);
+
+	/* Update last_idx */
+
+	while (ja->last_idx != ja->cur_idx &&
+	       ja->seq[ja->last_idx] < last_seq)
+		ja->last_idx = (ja->last_idx + 1) %
+			ca->sb.njournal_buckets;
+
+	if (c->journal.blocks_free)
+		goto out;
+
+	if (!free_journal_buckets(c))
+		goto out;
+
+	ja->cur_idx = (ja->cur_idx + 1) % ca->sb.njournal_buckets;
+	k->ptr[0] = MAKE_PTR(0,
+			     bucket_to_sector(c, ca->sb.d[ja->cur_idx]),
+			     ca->sb.nr_this_dev);
+	atomic_long_inc(&c->reclaimed_journal_buckets);
+
+	bkey_init(k);
+	SET_KEY_PTRS(k, 1);
+	c->journal.blocks_free = ca->sb.bucket_size >> c->block_bits;
+
+out:
+	if (!journal_full(&c->journal))
+		__closure_wake_up(&c->journal.wait);
+}
+
+void bch_journal_next(struct journal *j)
+{
+	atomic_t p = { 1 };
+
+	j->cur = (j->cur == j->w)
+		? &j->w[1]
+		: &j->w[0];
+
+	/*
+	 * The fifo_push() needs to happen at the same time as j->seq is
+	 * incremented for last_seq() to be calculated correctly
+	 */
+	BUG_ON(!fifo_push(&j->pin, p));
+	atomic_set(&fifo_back(&j->pin), 1);
+
+	j->cur->data->seq	= ++j->seq;
+	j->cur->dirty		= false;
+	j->cur->need_write	= false;
+	j->cur->data->keys	= 0;
+
+	if (fifo_full(&j->pin))
+		pr_debug("journal_pin full (%zu)\n", fifo_used(&j->pin));
+}
+
+static void journal_write_endio(struct bio *bio)
+{
+	struct journal_write *w = bio->bi_private;
+
+	cache_set_err_on(bio->bi_status, w->c, "journal io error");
+	closure_put(&w->c->journal.io);
+}
+
+static CLOSURE_CALLBACK(journal_write);
+
+static CLOSURE_CALLBACK(journal_write_done)
+{
+	closure_type(j, struct journal, io);
+	struct journal_write *w = (j->cur == j->w)
+		? &j->w[1]
+		: &j->w[0];
+
+	__closure_wake_up(&w->wait);
+	continue_at_nobarrier(cl, journal_write, bch_journal_wq);
+}
+
+static CLOSURE_CALLBACK(journal_write_unlock)
+	__releases(&c->journal.lock)
+{
+	closure_type(c, struct cache_set, journal.io);
+
+	c->journal.io_in_flight = 0;
+	spin_unlock(&c->journal.lock);
+}
+
+static CLOSURE_CALLBACK(journal_write_unlocked)
+	__releases(c->journal.lock)
+{
+	closure_type(c, struct cache_set, journal.io);
+	struct cache *ca = c->cache;
+	struct journal_write *w = c->journal.cur;
+	struct bkey *k = &c->journal.key;
+	unsigned int i, sectors = set_blocks(w->data, block_bytes(ca)) *
+		ca->sb.block_size;
+
+	struct bio *bio;
+	struct bio_list list;
+
+	bio_list_init(&list);
+
+	if (!w->need_write) {
+		closure_return_with_destructor(cl, journal_write_unlock);
+		return;
+	} else if (journal_full(&c->journal)) {
+		journal_reclaim(c);
+		spin_unlock(&c->journal.lock);
+
+		btree_flush_write(c);
+		continue_at(cl, journal_write, bch_journal_wq);
+		return;
+	}
+
+	c->journal.blocks_free -= set_blocks(w->data, block_bytes(ca));
+
+	w->data->btree_level = c->root->level;
+
+	bkey_copy(&w->data->btree_root, &c->root->key);
+	bkey_copy(&w->data->uuid_bucket, &c->uuid_bucket);
+
+	w->data->prio_bucket[ca->sb.nr_this_dev] = ca->prio_buckets[0];
+	w->data->magic		= jset_magic(&ca->sb);
+	w->data->version	= BCACHE_JSET_VERSION;
+	w->data->last_seq	= last_seq(&c->journal);
+	w->data->csum		= csum_set(w->data);
+
+	for (i = 0; i < KEY_PTRS(k); i++) {
+		ca = c->cache;
+		bio = &ca->journal.bio;
+
+		atomic_long_add(sectors, &ca->meta_sectors_written);
+
+		bio_reset(bio, ca->bdev, REQ_OP_WRITE | 
+			  REQ_SYNC | REQ_META | REQ_PREFLUSH | REQ_FUA);
+		bio->bi_iter.bi_sector	= PTR_OFFSET(k, i);
+		bio->bi_iter.bi_size = sectors << 9;
+
+		bio->bi_end_io	= journal_write_endio;
+		bio->bi_private = w;
+		bch_bio_map(bio, w->data);
+
+		trace_bcache_journal_write(bio, w->data->keys);
+		bio_list_add(&list, bio);
+
+		SET_PTR_OFFSET(k, i, PTR_OFFSET(k, i) + sectors);
+
+		ca->journal.seq[ca->journal.cur_idx] = w->data->seq;
+	}
+
+	/* If KEY_PTRS(k) == 0, this jset gets lost in air */
+	BUG_ON(i == 0);
+
+	atomic_dec_bug(&fifo_back(&c->journal.pin));
+	bch_journal_next(&c->journal);
+	journal_reclaim(c);
+
+	spin_unlock(&c->journal.lock);
+
+	while ((bio = bio_list_pop(&list)))
+		closure_bio_submit(c, bio, cl);
+
+	continue_at(cl, journal_write_done, NULL);
+}
+
+static CLOSURE_CALLBACK(journal_write)
+{
+	closure_type(c, struct cache_set, journal.io);
+
+	spin_lock(&c->journal.lock);
+	journal_write_unlocked(&cl->work);
+}
+
+static void journal_try_write(struct cache_set *c)
+	__releases(c->journal.lock)
+{
+	struct closure *cl = &c->journal.io;
+	struct journal_write *w = c->journal.cur;
+
+	w->need_write = true;
+
+	if (!c->journal.io_in_flight) {
+		c->journal.io_in_flight = 1;
+		closure_call(cl, journal_write_unlocked, NULL, &c->cl);
+	} else {
+		spin_unlock(&c->journal.lock);
+	}
+}
+
+static struct journal_write *journal_wait_for_write(struct cache_set *c,
+						    unsigned int nkeys)
+	__acquires(&c->journal.lock)
+{
+	size_t sectors;
+	struct closure cl;
+	bool wait = false;
+	struct cache *ca = c->cache;
+
+	closure_init_stack(&cl);
+
+	spin_lock(&c->journal.lock);
+
+	while (1) {
+		struct journal_write *w = c->journal.cur;
+
+		sectors = __set_blocks(w->data, w->data->keys + nkeys,
+				       block_bytes(ca)) * ca->sb.block_size;
+
+		if (sectors <= min_t(size_t,
+				     c->journal.blocks_free * ca->sb.block_size,
+				     PAGE_SECTORS << JSET_BITS))
+			return w;
+
+		if (wait)
+			closure_wait(&c->journal.wait, &cl);
+
+		if (!journal_full(&c->journal)) {
+			if (wait)
+				trace_bcache_journal_entry_full(c);
+
+			/*
+			 * XXX: If we were inserting so many keys that they
+			 * won't fit in an _empty_ journal write, we'll
+			 * deadlock. For now, handle this in
+			 * bch_keylist_realloc() - but something to think about.
+			 */
+			BUG_ON(!w->data->keys);
+
+			journal_try_write(c); /* unlocks */
+		} else {
+			if (wait)
+				trace_bcache_journal_full(c);
+
+			journal_reclaim(c);
+			spin_unlock(&c->journal.lock);
+
+			btree_flush_write(c);
+		}
+
+		closure_sync(&cl);
+		spin_lock(&c->journal.lock);
+		wait = true;
+	}
+}
+
+static void journal_write_work(struct work_struct *work)
+{
+	struct cache_set *c = container_of(to_delayed_work(work),
+					   struct cache_set,
+					   journal.work);
+	spin_lock(&c->journal.lock);
+	if (c->journal.cur->dirty)
+		journal_try_write(c);
+	else
+		spin_unlock(&c->journal.lock);
+}
+
+/*
+ * Entry point to the journalling code - bio_insert() and btree_invalidate()
+ * pass bch_journal() a list of keys to be journalled, and then
+ * bch_journal() hands those same keys off to btree_insert_async()
+ */
+
+atomic_t *bch_journal(struct cache_set *c,
+		      struct keylist *keys,
+		      struct closure *parent)
+{
+	struct journal_write *w;
+	atomic_t *ret;
+
+	/* No journaling if CACHE_SET_IO_DISABLE set already */
+	if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags)))
+		return NULL;
+
+	if (!CACHE_SYNC(&c->cache->sb))
+		return NULL;
+
+	w = journal_wait_for_write(c, bch_keylist_nkeys(keys));
+
+	memcpy(bset_bkey_last(w->data), keys->keys, bch_keylist_bytes(keys));
+	w->data->keys += bch_keylist_nkeys(keys);
+
+	ret = &fifo_back(&c->journal.pin);
+	atomic_inc(ret);
+
+	if (parent) {
+		closure_wait(&w->wait, parent);
+		journal_try_write(c);
+	} else if (!w->dirty) {
+		w->dirty = true;
+		queue_delayed_work(bch_flush_wq, &c->journal.work,
+				   msecs_to_jiffies(c->journal_delay_ms));
+		spin_unlock(&c->journal.lock);
+	} else {
+		spin_unlock(&c->journal.lock);
+	}
+
+
+	return ret;
+}
+
+void bch_journal_meta(struct cache_set *c, struct closure *cl)
+{
+	struct keylist keys;
+	atomic_t *ref;
+
+	bch_keylist_init(&keys);
+
+	ref = bch_journal(c, &keys, cl);
+	if (ref)
+		atomic_dec_bug(ref);
+}
+
+void bch_journal_free(struct cache_set *c)
+{
+	free_pages((unsigned long) c->journal.w[1].data, JSET_BITS);
+	free_pages((unsigned long) c->journal.w[0].data, JSET_BITS);
+	free_fifo(&c->journal.pin);
+}
+
+int bch_journal_alloc(struct cache_set *c)
+{
+	struct journal *j = &c->journal;
+
+	spin_lock_init(&j->lock);
+	spin_lock_init(&j->flush_write_lock);
+	INIT_DELAYED_WORK(&j->work, journal_write_work);
+
+	c->journal_delay_ms = 100;
+
+	j->w[0].c = c;
+	j->w[1].c = c;
+
+	if (!(init_fifo(&j->pin, JOURNAL_PIN, GFP_KERNEL)) ||
+	    !(j->w[0].data = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP, JSET_BITS)) ||
+	    !(j->w[1].data = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP, JSET_BITS)))
+		return -ENOMEM;
+
+	return 0;
+}

linux-7.2.3/drivers/md/bcache/journal.h

@@ -0,0 +1,175 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_JOURNAL_H
+#define _BCACHE_JOURNAL_H
+
+/*
+ * THE JOURNAL:
+ *
+ * The journal is treated as a circular buffer of buckets - a journal entry
+ * never spans two buckets. This means (not implemented yet) we can resize the
+ * journal at runtime, and will be needed for bcache on raw flash support.
+ *
+ * Journal entries contain a list of keys, ordered by the time they were
+ * inserted; thus journal replay just has to reinsert the keys.
+ *
+ * We also keep some things in the journal header that are logically part of the
+ * superblock - all the things that are frequently updated. This is for future
+ * bcache on raw flash support; the superblock (which will become another
+ * journal) can't be moved or wear leveled, so it contains just enough
+ * information to find the main journal, and the superblock only has to be
+ * rewritten when we want to move/wear level the main journal.
+ *
+ * Currently, we don't journal BTREE_REPLACE operations - this will hopefully be
+ * fixed eventually. This isn't a bug - BTREE_REPLACE is used for insertions
+ * from cache misses, which don't have to be journaled, and for writeback and
+ * moving gc we work around it by flushing the btree to disk before updating the
+ * gc information. But it is a potential issue with incremental garbage
+ * collection, and it's fragile.
+ *
+ * OPEN JOURNAL ENTRIES:
+ *
+ * Each journal entry contains, in the header, the sequence number of the last
+ * journal entry still open - i.e. that has keys that haven't been flushed to
+ * disk in the btree.
+ *
+ * We track this by maintaining a refcount for every open journal entry, in a
+ * fifo; each entry in the fifo corresponds to a particular journal
+ * entry/sequence number. When the refcount at the tail of the fifo goes to
+ * zero, we pop it off - thus, the size of the fifo tells us the number of open
+ * journal entries
+ *
+ * We take a refcount on a journal entry when we add some keys to a journal
+ * entry that we're going to insert (held by struct btree_op), and then when we
+ * insert those keys into the btree the btree write we're setting up takes a
+ * copy of that refcount (held by struct btree_write). That refcount is dropped
+ * when the btree write completes.
+ *
+ * A struct btree_write can only hold a refcount on a single journal entry, but
+ * might contain keys for many journal entries - we handle this by making sure
+ * it always has a refcount on the _oldest_ journal entry of all the journal
+ * entries it has keys for.
+ *
+ * JOURNAL RECLAIM:
+ *
+ * As mentioned previously, our fifo of refcounts tells us the number of open
+ * journal entries; from that and the current journal sequence number we compute
+ * last_seq - the oldest journal entry we still need. We write last_seq in each
+ * journal entry, and we also have to keep track of where it exists on disk so
+ * we don't overwrite it when we loop around the journal.
+ *
+ * To do that we track, for each journal bucket, the sequence number of the
+ * newest journal entry it contains - if we don't need that journal entry we
+ * don't need anything in that bucket anymore. From that we track the last
+ * journal bucket we still need; all this is tracked in struct journal_device
+ * and updated by journal_reclaim().
+ *
+ * JOURNAL FILLING UP:
+ *
+ * There are two ways the journal could fill up; either we could run out of
+ * space to write to, or we could have too many open journal entries and run out
+ * of room in the fifo of refcounts. Since those refcounts are decremented
+ * without any locking we can't safely resize that fifo, so we handle it the
+ * same way.
+ *
+ * If the journal fills up, we start flushing dirty btree nodes until we can
+ * allocate space for a journal write again - preferentially flushing btree
+ * nodes that are pinning the oldest journal entries first.
+ */
+
+/*
+ * Only used for holding the journal entries we read in btree_journal_read()
+ * during cache_registration
+ */
+struct journal_replay {
+	struct list_head	list;
+	atomic_t		*pin;
+	struct jset		j;
+};
+
+/*
+ * We put two of these in struct journal; we used them for writes to the
+ * journal that are being staged or in flight.
+ */
+struct journal_write {
+	struct jset		*data;
+#define JSET_BITS		3
+
+	struct cache_set	*c;
+	struct closure_waitlist	wait;
+	bool			dirty;
+	bool			need_write;
+};
+
+/* Embedded in struct cache_set */
+struct journal {
+	spinlock_t		lock;
+	spinlock_t		flush_write_lock;
+	bool			btree_flushing;
+	bool			do_reserve;
+	/* used when waiting because the journal was full */
+	struct closure_waitlist	wait;
+	struct closure		io;
+	int			io_in_flight;
+	struct delayed_work	work;
+
+	/* Number of blocks free in the bucket(s) we're currently writing to */
+	unsigned int		blocks_free;
+	uint64_t		seq;
+	DECLARE_FIFO(atomic_t, pin);
+
+	BKEY_PADDED(key);
+
+	struct journal_write	w[2], *cur;
+};
+
+/*
+ * Embedded in struct cache. First three fields refer to the array of journal
+ * buckets, in cache_sb.
+ */
+struct journal_device {
+	/*
+	 * For each journal bucket, contains the max sequence number of the
+	 * journal writes it contains - so we know when a bucket can be reused.
+	 */
+	uint64_t		seq[SB_JOURNAL_BUCKETS];
+
+	/* Journal bucket we're currently writing to */
+	unsigned int		cur_idx;
+
+	/* Last journal bucket that still contains an open journal entry */
+	unsigned int		last_idx;
+
+	/* Bio for journal reads/writes to this device */
+	struct bio		bio;
+	struct bio_vec		bv[8];
+};
+
+#define BTREE_FLUSH_NR	8
+
+#define journal_pin_cmp(c, l, r)				\
+	(fifo_idx(&(c)->journal.pin, (l)) > fifo_idx(&(c)->journal.pin, (r)))
+
+#define JOURNAL_PIN	20000
+
+#define journal_full(j)						\
+	(!(j)->blocks_free || fifo_free(&(j)->pin) <= 1)
+
+struct closure;
+struct cache_set;
+struct btree_op;
+struct keylist;
+
+atomic_t *bch_journal(struct cache_set *c,
+		      struct keylist *keys,
+		      struct closure *parent);
+void bch_journal_next(struct journal *j);
+void bch_journal_mark(struct cache_set *c, struct list_head *list);
+void bch_journal_meta(struct cache_set *c, struct closure *cl);
+int bch_journal_read(struct cache_set *c, struct list_head *list);
+int bch_journal_replay(struct cache_set *c, struct list_head *list);
+
+void bch_journal_free(struct cache_set *c);
+int bch_journal_alloc(struct cache_set *c);
+void bch_journal_space_reserve(struct journal *j);
+
+#endif /* _BCACHE_JOURNAL_H */

linux-7.2.3/drivers/md/bcache/movinggc.c

@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Moving/copying garbage collector
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+#include <trace/events/bcache.h>
+
+struct moving_io {
+	struct closure		cl;
+	struct keybuf_key	*w;
+	struct data_insert_op	op;
+	struct bbio		bio;
+};
+
+static bool moving_pred(struct keybuf *buf, struct bkey *k)
+{
+	struct cache_set *c = container_of(buf, struct cache_set,
+					   moving_gc_keys);
+	unsigned int i;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (ptr_available(c, k, i) &&
+		    GC_MOVE(PTR_BUCKET(c, k, i)))
+			return true;
+
+	return false;
+}
+
+/* Moving GC - IO loop */
+
+static CLOSURE_CALLBACK(moving_io_destructor)
+{
+	closure_type(io, struct moving_io, cl);
+
+	kfree(io);
+}
+
+static CLOSURE_CALLBACK(write_moving_finish)
+{
+	closure_type(io, struct moving_io, cl);
+	struct bio *bio = &io->bio.bio;
+
+	bio_free_pages(bio);
+
+	if (io->op.replace_collision)
+		trace_bcache_gc_copy_collision(&io->w->key);
+
+	bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
+
+	up(&io->op.c->moving_in_flight);
+
+	closure_return_with_destructor(cl, moving_io_destructor);
+}
+
+static void read_moving_endio(struct bio *bio)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+	struct moving_io *io = container_of(bio->bi_private,
+					    struct moving_io, cl);
+
+	if (bio->bi_status)
+		io->op.status = bio->bi_status;
+	else if (!KEY_DIRTY(&b->key) &&
+		 ptr_stale(io->op.c, &b->key, 0)) {
+		io->op.status = BLK_STS_IOERR;
+	}
+
+	bch_bbio_endio(io->op.c, bio, bio->bi_status, "reading data to move");
+}
+
+static void moving_init(struct moving_io *io)
+{
+	struct bio *bio = &io->bio.bio;
+
+	bio_init_inline(bio, NULL,
+		 DIV_ROUND_UP(KEY_SIZE(&io->w->key), PAGE_SECTORS), 0);
+	bio_get(bio);
+	bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0);
+
+	bio->bi_iter.bi_size	= KEY_SIZE(&io->w->key) << 9;
+	bio->bi_private		= &io->cl;
+	bch_bio_map(bio, NULL);
+}
+
+static CLOSURE_CALLBACK(write_moving)
+{
+	closure_type(io, struct moving_io, cl);
+	struct data_insert_op *op = &io->op;
+
+	if (!op->status) {
+		moving_init(io);
+
+		io->bio.bio.bi_iter.bi_sector = KEY_START(&io->w->key);
+		op->write_prio		= 1;
+		op->bio			= &io->bio.bio;
+
+		op->writeback		= KEY_DIRTY(&io->w->key);
+		op->csum		= KEY_CSUM(&io->w->key);
+
+		bkey_copy(&op->replace_key, &io->w->key);
+		op->replace		= true;
+
+		closure_call(&op->cl, bch_data_insert, NULL, cl);
+	}
+
+	continue_at(cl, write_moving_finish, op->wq);
+}
+
+static CLOSURE_CALLBACK(read_moving_submit)
+{
+	closure_type(io, struct moving_io, cl);
+	struct bio *bio = &io->bio.bio;
+
+	bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
+
+	continue_at(cl, write_moving, io->op.wq);
+}
+
+static void read_moving(struct cache_set *c)
+{
+	struct keybuf_key *w;
+	struct moving_io *io;
+	struct bio *bio;
+	struct closure cl;
+
+	closure_init_stack(&cl);
+
+	/* XXX: if we error, background writeback could stall indefinitely */
+
+	while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
+		w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
+					   &MAX_KEY, moving_pred);
+		if (!w)
+			break;
+
+		if (ptr_stale(c, &w->key, 0)) {
+			bch_keybuf_del(&c->moving_gc_keys, w);
+			continue;
+		}
+
+		io = kzalloc(sizeof(*io) + sizeof(struct bio_vec) *
+				DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
+				GFP_KERNEL);
+		if (!io)
+			goto err;
+
+		w->private	= io;
+		io->w		= w;
+		io->op.inode	= KEY_INODE(&w->key);
+		io->op.c	= c;
+		io->op.wq	= c->moving_gc_wq;
+
+		moving_init(io);
+		bio = &io->bio.bio;
+
+		bio->bi_opf = REQ_OP_READ;
+		bio->bi_end_io	= read_moving_endio;
+
+		if (bch_bio_alloc_pages(bio, GFP_KERNEL))
+			goto err;
+
+		trace_bcache_gc_copy(&w->key);
+
+		down(&c->moving_in_flight);
+		closure_call(&io->cl, read_moving_submit, NULL, &cl);
+	}
+
+	if (0) {
+err:		if (!IS_ERR_OR_NULL(w->private))
+			kfree(w->private);
+
+		bch_keybuf_del(&c->moving_gc_keys, w);
+	}
+
+	closure_sync(&cl);
+}
+
+static bool bucket_cmp(struct bucket *l, struct bucket *r)
+{
+	return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
+}
+
+static unsigned int bucket_heap_top(struct cache *ca)
+{
+	struct bucket *b;
+
+	return (b = heap_peek(&ca->heap)) ? GC_SECTORS_USED(b) : 0;
+}
+
+void bch_moving_gc(struct cache_set *c)
+{
+	struct cache *ca = c->cache;
+	struct bucket *b;
+	unsigned long sectors_to_move, reserve_sectors;
+
+	if (!c->copy_gc_enabled)
+		return;
+
+	mutex_lock(&c->bucket_lock);
+
+	sectors_to_move = 0;
+	reserve_sectors = ca->sb.bucket_size *
+			     fifo_used(&ca->free[RESERVE_MOVINGGC]);
+
+	ca->heap.used = 0;
+
+	for_each_bucket(b, ca) {
+		if (GC_MARK(b) == GC_MARK_METADATA ||
+		    !GC_SECTORS_USED(b) ||
+		    GC_SECTORS_USED(b) == ca->sb.bucket_size ||
+		    atomic_read(&b->pin))
+			continue;
+
+		if (!heap_full(&ca->heap)) {
+			sectors_to_move += GC_SECTORS_USED(b);
+			heap_add(&ca->heap, b, bucket_cmp);
+		} else if (bucket_cmp(b, heap_peek(&ca->heap))) {
+			sectors_to_move -= bucket_heap_top(ca);
+			sectors_to_move += GC_SECTORS_USED(b);
+
+			ca->heap.data[0] = b;
+			heap_sift(&ca->heap, 0, bucket_cmp);
+		}
+	}
+
+	while (sectors_to_move > reserve_sectors) {
+		heap_pop(&ca->heap, b, bucket_cmp);
+		sectors_to_move -= GC_SECTORS_USED(b);
+	}
+
+	while (heap_pop(&ca->heap, b, bucket_cmp))
+		SET_GC_MOVE(b, 1);
+
+	mutex_unlock(&c->bucket_lock);
+
+	c->moving_gc_keys.last_scanned = ZERO_KEY;
+
+	read_moving(c);
+}
+
+void bch_moving_init_cache_set(struct cache_set *c)
+{
+	bch_keybuf_init(&c->moving_gc_keys);
+	sema_init(&c->moving_in_flight, 64);
+}

linux-7.2.3/drivers/md/bcache/request.h

@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_REQUEST_H_
+#define _BCACHE_REQUEST_H_
+
+struct data_insert_op {
+	struct closure		cl;
+	struct cache_set	*c;
+	struct bio		*bio;
+	struct workqueue_struct *wq;
+
+	unsigned int		inode;
+	uint16_t		write_point;
+	uint16_t		write_prio;
+	blk_status_t		status;
+
+	union {
+		uint16_t	flags;
+
+	struct {
+		unsigned int	bypass:1;
+		unsigned int	writeback:1;
+		unsigned int	flush_journal:1;
+		unsigned int	csum:1;
+
+		unsigned int	replace:1;
+		unsigned int	replace_collision:1;
+
+		unsigned int	insert_data_done:1;
+	};
+	};
+
+	struct keylist		insert_keys;
+	BKEY_PADDED(replace_key);
+};
+
+unsigned int bch_get_congested(const struct cache_set *c);
+CLOSURE_CALLBACK(bch_data_insert);
+
+void bch_cached_dev_request_init(struct cached_dev *dc);
+void cached_dev_submit_bio(struct bio *bio);
+
+void bch_flash_dev_request_init(struct bcache_device *d);
+void flash_dev_submit_bio(struct bio *bio);
+
+extern struct kmem_cache *bch_search_cache;
+
+#endif /* _BCACHE_REQUEST_H_ */

linux-7.2.3/drivers/md/bcache/stats.c

@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * bcache stats code
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "stats.h"
+#include "btree.h"
+#include "sysfs.h"
+
+/*
+ * We keep absolute totals of various statistics, and addionally a set of three
+ * rolling averages.
+ *
+ * Every so often, a timer goes off and rescales the rolling averages.
+ * accounting_rescale[] is how many times the timer has to go off before we
+ * rescale each set of numbers; that gets us half lives of 5 minutes, one hour,
+ * and one day.
+ *
+ * accounting_delay is how often the timer goes off - 22 times in 5 minutes,
+ * and accounting_weight is what we use to rescale:
+ *
+ * pow(31 / 32, 22) ~= 1/2
+ *
+ * So that we don't have to increment each set of numbers every time we (say)
+ * get a cache hit, we increment a single atomic_t in acc->collector, and when
+ * the rescale function runs it resets the atomic counter to 0 and adds its
+ * old value to each of the exported numbers.
+ *
+ * To reduce rounding error, the numbers in struct cache_stats are all
+ * stored left shifted by 16, and scaled back in the sysfs show() function.
+ */
+
+static const unsigned int DAY_RESCALE		= 288;
+static const unsigned int HOUR_RESCALE		= 12;
+static const unsigned int FIVE_MINUTE_RESCALE	= 1;
+static const unsigned int accounting_delay	= (HZ * 300) / 22;
+static const unsigned int accounting_weight	= 32;
+
+/* sysfs reading/writing */
+
+read_attribute(cache_hits);
+read_attribute(cache_misses);
+read_attribute(cache_bypass_hits);
+read_attribute(cache_bypass_misses);
+read_attribute(cache_hit_ratio);
+read_attribute(cache_miss_collisions);
+read_attribute(bypassed);
+
+SHOW(bch_stats)
+{
+	struct cache_stats *s =
+		container_of(kobj, struct cache_stats, kobj);
+#define var(stat)		(s->stat >> 16)
+	var_print(cache_hits);
+	var_print(cache_misses);
+	var_print(cache_bypass_hits);
+	var_print(cache_bypass_misses);
+
+	sysfs_print(cache_hit_ratio,
+		    DIV_SAFE(var(cache_hits) * 100,
+			     var(cache_hits) + var(cache_misses)));
+
+	var_print(cache_miss_collisions);
+	sysfs_hprint(bypassed,	var(sectors_bypassed) << 9);
+#undef var
+	return 0;
+}
+
+STORE(bch_stats)
+{
+	return size;
+}
+
+static void bch_stats_release(struct kobject *k)
+{
+}
+
+static struct attribute *bch_stats_attrs[] = {
+	&sysfs_cache_hits,
+	&sysfs_cache_misses,
+	&sysfs_cache_bypass_hits,
+	&sysfs_cache_bypass_misses,
+	&sysfs_cache_hit_ratio,
+	&sysfs_cache_miss_collisions,
+	&sysfs_bypassed,
+	NULL
+};
+ATTRIBUTE_GROUPS(bch_stats);
+static KTYPE(bch_stats);
+
+int bch_cache_accounting_add_kobjs(struct cache_accounting *acc,
+				   struct kobject *parent)
+{
+	int ret = kobject_add(&acc->total.kobj, parent,
+			      "stats_total");
+	ret = ret ?: kobject_add(&acc->five_minute.kobj, parent,
+				 "stats_five_minute");
+	ret = ret ?: kobject_add(&acc->hour.kobj, parent,
+				 "stats_hour");
+	ret = ret ?: kobject_add(&acc->day.kobj, parent,
+				 "stats_day");
+	return ret;
+}
+
+void bch_cache_accounting_clear(struct cache_accounting *acc)
+{
+	acc->total.cache_hits = 0;
+	acc->total.cache_misses = 0;
+	acc->total.cache_bypass_hits = 0;
+	acc->total.cache_bypass_misses = 0;
+	acc->total.cache_miss_collisions = 0;
+	acc->total.sectors_bypassed = 0;
+}
+
+void bch_cache_accounting_destroy(struct cache_accounting *acc)
+{
+	kobject_put(&acc->total.kobj);
+	kobject_put(&acc->five_minute.kobj);
+	kobject_put(&acc->hour.kobj);
+	kobject_put(&acc->day.kobj);
+
+	atomic_set(&acc->closing, 1);
+	if (timer_delete_sync(&acc->timer))
+		closure_return(&acc->cl);
+}
+
+/* EWMA scaling */
+
+static void scale_stat(unsigned long *stat)
+{
+	*stat =  ewma_add(*stat, 0, accounting_weight, 0);
+}
+
+static void scale_stats(struct cache_stats *stats, unsigned long rescale_at)
+{
+	if (++stats->rescale == rescale_at) {
+		stats->rescale = 0;
+		scale_stat(&stats->cache_hits);
+		scale_stat(&stats->cache_misses);
+		scale_stat(&stats->cache_bypass_hits);
+		scale_stat(&stats->cache_bypass_misses);
+		scale_stat(&stats->cache_miss_collisions);
+		scale_stat(&stats->sectors_bypassed);
+	}
+}
+
+static void scale_accounting(struct timer_list *t)
+{
+	struct cache_accounting *acc = timer_container_of(acc, t, timer);
+
+#define move_stat(name) do {						\
+	unsigned int t = atomic_xchg(&acc->collector.name, 0);		\
+	t <<= 16;							\
+	acc->five_minute.name += t;					\
+	acc->hour.name += t;						\
+	acc->day.name += t;						\
+	acc->total.name += t;						\
+} while (0)
+
+	move_stat(cache_hits);
+	move_stat(cache_misses);
+	move_stat(cache_bypass_hits);
+	move_stat(cache_bypass_misses);
+	move_stat(cache_miss_collisions);
+	move_stat(sectors_bypassed);
+
+	scale_stats(&acc->total, 0);
+	scale_stats(&acc->day, DAY_RESCALE);
+	scale_stats(&acc->hour, HOUR_RESCALE);
+	scale_stats(&acc->five_minute, FIVE_MINUTE_RESCALE);
+
+	acc->timer.expires += accounting_delay;
+
+	if (!atomic_read(&acc->closing))
+		add_timer(&acc->timer);
+	else
+		closure_return(&acc->cl);
+}
+
+static void mark_cache_stats(struct cache_stat_collector *stats,
+			     bool hit, bool bypass)
+{
+	if (!bypass)
+		if (hit)
+			atomic_inc(&stats->cache_hits);
+		else
+			atomic_inc(&stats->cache_misses);
+	else
+		if (hit)
+			atomic_inc(&stats->cache_bypass_hits);
+		else
+			atomic_inc(&stats->cache_bypass_misses);
+}
+
+void bch_mark_cache_accounting(struct cache_set *c, struct bcache_device *d,
+			       bool hit, bool bypass)
+{
+	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+
+	mark_cache_stats(&dc->accounting.collector, hit, bypass);
+	mark_cache_stats(&c->accounting.collector, hit, bypass);
+}
+
+void bch_mark_cache_miss_collision(struct cache_set *c, struct bcache_device *d)
+{
+	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+
+	atomic_inc(&dc->accounting.collector.cache_miss_collisions);
+	atomic_inc(&c->accounting.collector.cache_miss_collisions);
+}
+
+void bch_mark_sectors_bypassed(struct cache_set *c, struct cached_dev *dc,
+			       int sectors)
+{
+	atomic_add(sectors, &dc->accounting.collector.sectors_bypassed);
+	atomic_add(sectors, &c->accounting.collector.sectors_bypassed);
+}
+
+void bch_cache_accounting_init(struct cache_accounting *acc,
+			       struct closure *parent)
+{
+	kobject_init(&acc->total.kobj,		&bch_stats_ktype);
+	kobject_init(&acc->five_minute.kobj,	&bch_stats_ktype);
+	kobject_init(&acc->hour.kobj,		&bch_stats_ktype);
+	kobject_init(&acc->day.kobj,		&bch_stats_ktype);
+
+	closure_init(&acc->cl, parent);
+	timer_setup(&acc->timer, scale_accounting, 0);
+	acc->timer.expires	= jiffies + accounting_delay;
+	add_timer(&acc->timer);
+}

linux-7.2.3/drivers/md/bcache/stats.h

@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_STATS_H_
+#define _BCACHE_STATS_H_
+
+struct cache_stat_collector {
+	atomic_t cache_hits;
+	atomic_t cache_misses;
+	atomic_t cache_bypass_hits;
+	atomic_t cache_bypass_misses;
+	atomic_t cache_miss_collisions;
+	atomic_t sectors_bypassed;
+};
+
+struct cache_stats {
+	struct kobject		kobj;
+
+	unsigned long cache_hits;
+	unsigned long cache_misses;
+	unsigned long cache_bypass_hits;
+	unsigned long cache_bypass_misses;
+	unsigned long cache_miss_collisions;
+	unsigned long sectors_bypassed;
+
+	unsigned int		rescale;
+};
+
+struct cache_accounting {
+	struct closure		cl;
+	struct timer_list	timer;
+	atomic_t		closing;
+
+	struct cache_stat_collector collector;
+
+	struct cache_stats total;
+	struct cache_stats five_minute;
+	struct cache_stats hour;
+	struct cache_stats day;
+};
+
+struct cache_set;
+struct cached_dev;
+struct bcache_device;
+
+void bch_cache_accounting_init(struct cache_accounting *acc,
+			       struct closure *parent);
+
+int bch_cache_accounting_add_kobjs(struct cache_accounting *acc,
+				   struct kobject *parent);
+
+void bch_cache_accounting_clear(struct cache_accounting *acc);
+
+void bch_cache_accounting_destroy(struct cache_accounting *acc);
+
+void bch_mark_cache_accounting(struct cache_set *c, struct bcache_device *d,
+			       bool hit, bool bypass);
+void bch_mark_cache_miss_collision(struct cache_set *c,
+				   struct bcache_device *d);
+void bch_mark_sectors_bypassed(struct cache_set *c,
+			       struct cached_dev *dc,
+			       int sectors);
+
+#endif /* _BCACHE_STATS_H_ */

linux-7.2.3/drivers/md/bcache/sysfs.h

@@ -0,0 +1,142 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_SYSFS_H_
+#define _BCACHE_SYSFS_H_
+
+#define KTYPE(type)							\
+const struct kobj_type type ## _ktype = {					\
+	.release	= type ## _release,				\
+	.sysfs_ops	= &((const struct sysfs_ops) {			\
+		.show	= type ## _show,				\
+		.store	= type ## _store				\
+	}),								\
+	.default_groups	= type ## _groups				\
+}
+
+#define SHOW(fn)							\
+static ssize_t fn ## _show(struct kobject *kobj, struct attribute *attr,\
+			   char *buf)					\
+
+#define STORE(fn)							\
+static ssize_t fn ## _store(struct kobject *kobj, struct attribute *attr,\
+			    const char *buf, size_t size)		\
+
+#define SHOW_LOCKED(fn)							\
+SHOW(fn)								\
+{									\
+	ssize_t ret;							\
+	mutex_lock(&bch_register_lock);					\
+	ret = __ ## fn ## _show(kobj, attr, buf);			\
+	mutex_unlock(&bch_register_lock);				\
+	return ret;							\
+}
+
+#define STORE_LOCKED(fn)						\
+STORE(fn)								\
+{									\
+	ssize_t ret;							\
+	mutex_lock(&bch_register_lock);					\
+	ret = __ ## fn ## _store(kobj, attr, buf, size);		\
+	mutex_unlock(&bch_register_lock);				\
+	return ret;							\
+}
+
+#define __sysfs_attribute(_name, _mode)					\
+	static struct attribute sysfs_##_name =				\
+		{ .name = #_name, .mode = _mode }
+
+#define write_attribute(n)	__sysfs_attribute(n, 0200)
+#define read_attribute(n)	__sysfs_attribute(n, 0444)
+#define rw_attribute(n)		__sysfs_attribute(n, 0644)
+
+#define sysfs_printf(file, fmt, ...)					\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return sysfs_emit(buf, fmt "\n", __VA_ARGS__);	\
+} while (0)
+
+#define sysfs_print(file, var)						\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return sysfs_emit(buf,						\
+				__builtin_types_compatible_p(typeof(var), int)		\
+					 ? "%i\n" :				\
+				__builtin_types_compatible_p(typeof(var), unsigned int)	\
+					 ? "%u\n" :				\
+				__builtin_types_compatible_p(typeof(var), long)		\
+					 ? "%li\n" :			\
+				__builtin_types_compatible_p(typeof(var), unsigned long)\
+					 ? "%lu\n" :			\
+				__builtin_types_compatible_p(typeof(var), int64_t)	\
+					 ? "%lli\n" :			\
+				__builtin_types_compatible_p(typeof(var), uint64_t)	\
+					 ? "%llu\n" :			\
+				__builtin_types_compatible_p(typeof(var), const char *)	\
+					 ? "%s\n" : "%i\n", var);	\
+} while (0)
+
+#define sysfs_hprint(file, val)						\
+do {									\
+	if (attr == &sysfs_ ## file) {					\
+		ssize_t ret = bch_hprint(buf, val);			\
+		strcat(buf, "\n");					\
+		return ret + 1;						\
+	}								\
+} while (0)
+
+#define var_printf(_var, fmt)	sysfs_printf(_var, fmt, var(_var))
+#define var_print(_var)		sysfs_print(_var, var(_var))
+#define var_hprint(_var)	sysfs_hprint(_var, var(_var))
+
+#define sysfs_strtoul(file, var)					\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoul_safe(buf, var) ?: (ssize_t) size;	\
+} while (0)
+
+#define sysfs_strtoul_bool(file, var)					\
+do {									\
+	if (attr == &sysfs_ ## file) {					\
+		unsigned long v = strtoul_or_return(buf);		\
+									\
+		var = v ? 1 : 0;					\
+		return size;						\
+	}								\
+} while (0)
+
+#define sysfs_strtoul_clamp(file, var, min, max)			\
+do {									\
+	if (attr == &sysfs_ ## file) {					\
+		unsigned long v = 0;					\
+		ssize_t ret;						\
+		ret = strtoul_safe_clamp(buf, v, min, max);		\
+		if (!ret) {						\
+			var = v;					\
+			return size;					\
+		}							\
+		return ret;						\
+	}								\
+} while (0)
+
+#define strtoul_or_return(cp)						\
+({									\
+	unsigned long _v;						\
+	int _r = kstrtoul(cp, 10, &_v);					\
+	if (_r)								\
+		return _r;						\
+	_v;								\
+})
+
+#define strtoi_h_or_return(cp, v)					\
+do {									\
+	int _r = strtoi_h(cp, &v);					\
+	if (_r)								\
+		return _r;						\
+} while (0)
+
+#define sysfs_hatoi(file, var)						\
+do {									\
+	if (attr == &sysfs_ ## file)					\
+		return strtoi_h(buf, &var) ?: (ssize_t) size;		\
+} while (0)
+
+#endif  /* _BCACHE_SYSFS_H_ */

linux-7.2.3/drivers/md/bcache/trace.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "bcache.h"
+#include "btree.h"
+
+#include <linux/blktrace_api.h>
+#include <linux/module.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/bcache.h>
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_request_start);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_request_end);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_bypass_sequential);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_bypass_congested);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_read);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_write);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_read_retry);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_cache_insert);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_journal_replay_key);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_journal_write);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_journal_full);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_journal_entry_full);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_cache_cannibalize);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_read);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_write);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_node_alloc);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_node_alloc_fail);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_node_free);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_gc_coalesce);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_gc_start);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_gc_end);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_gc_copy);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_gc_copy_collision);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_insert_key);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_node_split);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_node_compact);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_btree_set_root);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_invalidate);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_alloc_fail);
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_writeback);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bcache_writeback_collision);

linux-7.2.3/drivers/md/bcache/util.c

@@ -0,0 +1,287 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * random utility code, for bcache but in theory not specific to bcache
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/types.h>
+#include <linux/sched/clock.h>
+
+#include "util.h"
+
+#define simple_strtoint(c, end, base)	simple_strtol(c, end, base)
+#define simple_strtouint(c, end, base)	simple_strtoul(c, end, base)
+
+#define STRTO_H(name, type)					\
+int bch_ ## name ## _h(const char *cp, type *res)		\
+{								\
+	int u = 0;						\
+	char *e;						\
+	type i = simple_ ## name(cp, &e, 10);			\
+								\
+	switch (tolower(*e)) {					\
+	default:						\
+		return -EINVAL;					\
+	case 'y':						\
+	case 'z':						\
+		u++;						\
+		fallthrough;					\
+	case 'e':						\
+		u++;						\
+		fallthrough;					\
+	case 'p':						\
+		u++;						\
+		fallthrough;					\
+	case 't':						\
+		u++;						\
+		fallthrough;					\
+	case 'g':						\
+		u++;						\
+		fallthrough;					\
+	case 'm':						\
+		u++;						\
+		fallthrough;					\
+	case 'k':						\
+		u++;						\
+		if (e++ == cp)					\
+			return -EINVAL;				\
+		fallthrough;					\
+	case '\n':						\
+	case '\0':						\
+		if (*e == '\n')					\
+			e++;					\
+	}							\
+								\
+	if (*e)							\
+		return -EINVAL;					\
+								\
+	while (u--) {						\
+		if ((type) ~0 > 0 &&				\
+		    (type) ~0 / 1024 <= i)			\
+			return -EINVAL;				\
+		if ((i > 0 && ANYSINT_MAX(type) / 1024 < i) ||	\
+		    (i < 0 && -ANYSINT_MAX(type) / 1024 > i))	\
+			return -EINVAL;				\
+		i *= 1024;					\
+	}							\
+								\
+	*res = i;						\
+	return 0;						\
+}								\
+
+STRTO_H(strtoint, int)
+STRTO_H(strtouint, unsigned int)
+STRTO_H(strtoll, long long)
+STRTO_H(strtoull, unsigned long long)
+
+/**
+ * bch_hprint - formats @v to human readable string for sysfs.
+ * @buf: the (at least 8 byte) buffer to format the result into.
+ * @v: signed 64 bit integer
+ *
+ * Returns the number of bytes used by format.
+ */
+ssize_t bch_hprint(char *buf, int64_t v)
+{
+	static const char units[] = "?kMGTPEZY";
+	int u = 0, t;
+
+	uint64_t q;
+
+	if (v < 0)
+		q = -v;
+	else
+		q = v;
+
+	/* For as long as the number is more than 3 digits, but at least
+	 * once, shift right / divide by 1024.  Keep the remainder for
+	 * a digit after the decimal point.
+	 */
+	do {
+		u++;
+
+		t = q & ~(~0 << 10);
+		q >>= 10;
+	} while (q >= 1000);
+
+	if (v < 0)
+		/* '-', up to 3 digits, '.', 1 digit, 1 character, null;
+		 * yields 8 bytes.
+		 */
+		return sprintf(buf, "-%llu.%i%c", q, t * 10 / 1024, units[u]);
+	else
+		return sprintf(buf, "%llu.%i%c", q, t * 10 / 1024, units[u]);
+}
+
+bool bch_is_zero(const char *p, size_t n)
+{
+	size_t i;
+
+	for (i = 0; i < n; i++)
+		if (p[i])
+			return false;
+	return true;
+}
+
+int bch_parse_uuid(const char *s, char *uuid)
+{
+	size_t i, j, x;
+
+	memset(uuid, 0, 16);
+
+	for (i = 0, j = 0;
+	     i < strspn(s, "-0123456789:ABCDEFabcdef") && j < 32;
+	     i++) {
+		x = s[i] | 32;
+
+		switch (x) {
+		case '0'...'9':
+			x -= '0';
+			break;
+		case 'a'...'f':
+			x -= 'a' - 10;
+			break;
+		default:
+			continue;
+		}
+
+		if (!(j & 1))
+			x <<= 4;
+		uuid[j++ >> 1] |= x;
+	}
+	return i;
+}
+
+void bch_time_stats_update(struct time_stats *stats, uint64_t start_time)
+{
+	uint64_t now, duration, last;
+
+	spin_lock(&stats->lock);
+
+	now		= local_clock();
+	duration	= time_after64(now, start_time)
+		? now - start_time : 0;
+	last		= time_after64(now, stats->last)
+		? now - stats->last : 0;
+
+	stats->max_duration = max(stats->max_duration, duration);
+
+	if (stats->last) {
+		ewma_add(stats->average_duration, duration, 8, 8);
+
+		if (stats->average_frequency)
+			ewma_add(stats->average_frequency, last, 8, 8);
+		else
+			stats->average_frequency  = last << 8;
+	} else {
+		stats->average_duration  = duration << 8;
+	}
+
+	stats->last = now ?: 1;
+
+	spin_unlock(&stats->lock);
+}
+
+/**
+ * bch_next_delay() - update ratelimiting statistics and calculate next delay
+ * @d: the struct bch_ratelimit to update
+ * @done: the amount of work done, in arbitrary units
+ *
+ * Increment @d by the amount of work done, and return how long to delay in
+ * jiffies until the next time to do some work.
+ */
+uint64_t bch_next_delay(struct bch_ratelimit *d, uint64_t done)
+{
+	uint64_t now = local_clock();
+
+	d->next += div_u64(done * NSEC_PER_SEC, atomic_long_read(&d->rate));
+
+	/* Bound the time.  Don't let us fall further than 2 seconds behind
+	 * (this prevents unnecessary backlog that would make it impossible
+	 * to catch up).  If we're ahead of the desired writeback rate,
+	 * don't let us sleep more than 2.5 seconds (so we can notice/respond
+	 * if the control system tells us to speed up!).
+	 */
+	if (time_before64(now + NSEC_PER_SEC * 5LLU / 2LLU, d->next))
+		d->next = now + NSEC_PER_SEC * 5LLU / 2LLU;
+
+	if (time_after64(now - NSEC_PER_SEC * 2, d->next))
+		d->next = now - NSEC_PER_SEC * 2;
+
+	return time_after64(d->next, now)
+		? div_u64(d->next - now, NSEC_PER_SEC / HZ)
+		: 0;
+}
+
+/*
+ * Generally it isn't good to access .bi_io_vec and .bi_vcnt directly,
+ * the preferred way is bio_add_page, but in this case, bch_bio_map()
+ * supposes that the bvec table is empty, so it is safe to access
+ * .bi_vcnt & .bi_io_vec in this way even after multipage bvec is
+ * supported.
+ */
+void bch_bio_map(struct bio *bio, void *base)
+{
+	size_t size = bio->bi_iter.bi_size;
+	struct bio_vec *bv = bio->bi_io_vec;
+
+	BUG_ON(!bio->bi_iter.bi_size);
+	BUG_ON(bio->bi_vcnt);
+
+	bv->bv_offset = base ? offset_in_page(base) : 0;
+	goto start;
+
+	for (; size; bio->bi_vcnt++, bv++) {
+		bv->bv_offset	= 0;
+start:		bv->bv_len	= min_t(size_t, PAGE_SIZE - bv->bv_offset,
+					size);
+		if (base) {
+			bv->bv_page = is_vmalloc_addr(base)
+				? vmalloc_to_page(base)
+				: virt_to_page(base);
+
+			base += bv->bv_len;
+		}
+
+		size -= bv->bv_len;
+	}
+}
+
+/**
+ * bch_bio_alloc_pages - allocates a single page for each bvec in a bio
+ * @bio: bio to allocate pages for
+ * @gfp_mask: flags for allocation
+ *
+ * Allocates pages up to @bio->bi_vcnt.
+ *
+ * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
+ * freed.
+ */
+int bch_bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
+{
+	int i;
+	struct bio_vec *bv;
+
+	/*
+	 * This is called on freshly new bio, so it is safe to access the
+	 * bvec table directly.
+	 */
+	for (i = 0, bv = bio->bi_io_vec; i < bio->bi_vcnt; bv++, i++) {
+		bv->bv_page = alloc_page(gfp_mask);
+		if (!bv->bv_page) {
+			while (--bv >= bio->bi_io_vec)
+				__free_page(bv->bv_page);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}

linux-7.2.3/drivers/md/bcache/util.h

@@ -0,0 +1,561 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _BCACHE_UTIL_H
+#define _BCACHE_UTIL_H
+
+#include <linux/blkdev.h>
+#include <linux/closure.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/sched/clock.h>
+#include <linux/llist.h>
+#include <linux/ratelimit.h>
+#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
+#include <linux/crc64.h>
+
+struct closure;
+
+#ifdef CONFIG_BCACHE_DEBUG
+
+#define EBUG_ON(cond)			BUG_ON(cond)
+#define atomic_dec_bug(v)	BUG_ON(atomic_dec_return(v) < 0)
+#define atomic_inc_bug(v, i)	BUG_ON(atomic_inc_return(v) <= i)
+
+#else /* DEBUG */
+
+#define EBUG_ON(cond)		do { if (cond) do {} while (0); } while (0)
+#define atomic_dec_bug(v)	atomic_dec(v)
+#define atomic_inc_bug(v, i)	atomic_inc(v)
+
+#endif
+
+#define DECLARE_HEAP(type, name)					\
+	struct {							\
+		size_t size, used;					\
+		type *data;						\
+	} name
+
+#define init_heap(heap, _size, gfp)					\
+({									\
+	size_t _bytes;							\
+	(heap)->used = 0;						\
+	(heap)->size = (_size);						\
+	_bytes = (heap)->size * sizeof(*(heap)->data);			\
+	(heap)->data = kvmalloc(_bytes, (gfp) & GFP_KERNEL);		\
+	(heap)->data;							\
+})
+
+#define free_heap(heap)							\
+do {									\
+	kvfree((heap)->data);						\
+	(heap)->data = NULL;						\
+} while (0)
+
+#define heap_swap(h, i, j)	swap((h)->data[i], (h)->data[j])
+
+#define heap_sift(h, i, cmp)						\
+do {									\
+	size_t _r, _j = i;						\
+									\
+	for (; _j * 2 + 1 < (h)->used; _j = _r) {			\
+		_r = _j * 2 + 1;					\
+		if (_r + 1 < (h)->used &&				\
+		    cmp((h)->data[_r], (h)->data[_r + 1]))		\
+			_r++;						\
+									\
+		if (cmp((h)->data[_r], (h)->data[_j]))			\
+			break;						\
+		heap_swap(h, _r, _j);					\
+	}								\
+} while (0)
+
+#define heap_sift_down(h, i, cmp)					\
+do {									\
+	while (i) {							\
+		size_t p = (i - 1) / 2;					\
+		if (cmp((h)->data[i], (h)->data[p]))			\
+			break;						\
+		heap_swap(h, i, p);					\
+		i = p;							\
+	}								\
+} while (0)
+
+#define heap_add(h, d, cmp)						\
+({									\
+	bool _r = !heap_full(h);					\
+	if (_r) {							\
+		size_t _i = (h)->used++;				\
+		(h)->data[_i] = d;					\
+									\
+		heap_sift_down(h, _i, cmp);				\
+		heap_sift(h, _i, cmp);					\
+	}								\
+	_r;								\
+})
+
+#define heap_pop(h, d, cmp)						\
+({									\
+	bool _r = (h)->used;						\
+	if (_r) {							\
+		(d) = (h)->data[0];					\
+		(h)->used--;						\
+		heap_swap(h, 0, (h)->used);				\
+		heap_sift(h, 0, cmp);					\
+	}								\
+	_r;								\
+})
+
+#define heap_peek(h)	((h)->used ? (h)->data[0] : NULL)
+
+#define heap_full(h)	((h)->used == (h)->size)
+
+#define DECLARE_FIFO(type, name)					\
+	struct {							\
+		size_t front, back, size, mask;				\
+		type *data;						\
+	} name
+
+#define fifo_for_each(c, fifo, iter)					\
+	for (iter = (fifo)->front;					\
+	     c = (fifo)->data[iter], iter != (fifo)->back;		\
+	     iter = (iter + 1) & (fifo)->mask)
+
+#define __init_fifo(fifo, gfp)						\
+({									\
+	size_t _allocated_size, _bytes;					\
+	BUG_ON(!(fifo)->size);						\
+									\
+	_allocated_size = roundup_pow_of_two((fifo)->size + 1);		\
+	_bytes = _allocated_size * sizeof(*(fifo)->data);		\
+									\
+	(fifo)->mask = _allocated_size - 1;				\
+	(fifo)->front = (fifo)->back = 0;				\
+									\
+	(fifo)->data = kvmalloc(_bytes, (gfp) & GFP_KERNEL);		\
+	(fifo)->data;							\
+})
+
+#define init_fifo_exact(fifo, _size, gfp)				\
+({									\
+	(fifo)->size = (_size);						\
+	__init_fifo(fifo, gfp);						\
+})
+
+#define init_fifo(fifo, _size, gfp)					\
+({									\
+	(fifo)->size = (_size);						\
+	if ((fifo)->size > 4)						\
+		(fifo)->size = roundup_pow_of_two((fifo)->size) - 1;	\
+	__init_fifo(fifo, gfp);						\
+})
+
+#define free_fifo(fifo)							\
+do {									\
+	kvfree((fifo)->data);						\
+	(fifo)->data = NULL;						\
+} while (0)
+
+#define fifo_used(fifo)		(((fifo)->back - (fifo)->front) & (fifo)->mask)
+#define fifo_free(fifo)		((fifo)->size - fifo_used(fifo))
+
+#define fifo_empty(fifo)	(!fifo_used(fifo))
+#define fifo_full(fifo)		(!fifo_free(fifo))
+
+#define fifo_front(fifo)	((fifo)->data[(fifo)->front])
+#define fifo_back(fifo)							\
+	((fifo)->data[((fifo)->back - 1) & (fifo)->mask])
+
+#define fifo_idx(fifo, p)	(((p) - &fifo_front(fifo)) & (fifo)->mask)
+
+#define fifo_push_back(fifo, i)						\
+({									\
+	bool _r = !fifo_full((fifo));					\
+	if (_r) {							\
+		(fifo)->data[(fifo)->back++] = (i);			\
+		(fifo)->back &= (fifo)->mask;				\
+	}								\
+	_r;								\
+})
+
+#define fifo_pop_front(fifo, i)						\
+({									\
+	bool _r = !fifo_empty((fifo));					\
+	if (_r) {							\
+		(i) = (fifo)->data[(fifo)->front++];			\
+		(fifo)->front &= (fifo)->mask;				\
+	}								\
+	_r;								\
+})
+
+#define fifo_push_front(fifo, i)					\
+({									\
+	bool _r = !fifo_full((fifo));					\
+	if (_r) {							\
+		--(fifo)->front;					\
+		(fifo)->front &= (fifo)->mask;				\
+		(fifo)->data[(fifo)->front] = (i);			\
+	}								\
+	_r;								\
+})
+
+#define fifo_pop_back(fifo, i)						\
+({									\
+	bool _r = !fifo_empty((fifo));					\
+	if (_r) {							\
+		--(fifo)->back;						\
+		(fifo)->back &= (fifo)->mask;				\
+		(i) = (fifo)->data[(fifo)->back]			\
+	}								\
+	_r;								\
+})
+
+#define fifo_push(fifo, i)	fifo_push_back(fifo, (i))
+#define fifo_pop(fifo, i)	fifo_pop_front(fifo, (i))
+
+#define fifo_swap(l, r)							\
+do {									\
+	swap((l)->front, (r)->front);					\
+	swap((l)->back, (r)->back);					\
+	swap((l)->size, (r)->size);					\
+	swap((l)->mask, (r)->mask);					\
+	swap((l)->data, (r)->data);					\
+} while (0)
+
+#define fifo_move(dest, src)						\
+do {									\
+	typeof(*((dest)->data)) _t;					\
+	while (!fifo_full(dest) &&					\
+	       fifo_pop(src, _t))					\
+		fifo_push(dest, _t);					\
+} while (0)
+
+/*
+ * Simple array based allocator - preallocates a number of elements and you can
+ * never allocate more than that, also has no locking.
+ *
+ * Handy because if you know you only need a fixed number of elements you don't
+ * have to worry about memory allocation failure, and sometimes a mempool isn't
+ * what you want.
+ *
+ * We treat the free elements as entries in a singly linked list, and the
+ * freelist as a stack - allocating and freeing push and pop off the freelist.
+ */
+
+#define DECLARE_ARRAY_ALLOCATOR(type, name, size)			\
+	struct {							\
+		type	*freelist;					\
+		type	data[size];					\
+	} name
+
+#define array_alloc(array)						\
+({									\
+	typeof((array)->freelist) _ret = (array)->freelist;		\
+									\
+	if (_ret)							\
+		(array)->freelist = *((typeof((array)->freelist) *) _ret);\
+									\
+	_ret;								\
+})
+
+#define array_free(array, ptr)						\
+do {									\
+	typeof((array)->freelist) _ptr = ptr;				\
+									\
+	*((typeof((array)->freelist) *) _ptr) = (array)->freelist;	\
+	(array)->freelist = _ptr;					\
+} while (0)
+
+#define array_allocator_init(array)					\
+do {									\
+	typeof((array)->freelist) _i;					\
+									\
+	BUILD_BUG_ON(sizeof((array)->data[0]) < sizeof(void *));	\
+	(array)->freelist = NULL;					\
+									\
+	for (_i = (array)->data;					\
+	     _i < (array)->data + ARRAY_SIZE((array)->data);		\
+	     _i++)							\
+		array_free(array, _i);					\
+} while (0)
+
+#define array_freelist_empty(array)	((array)->freelist == NULL)
+
+#define ANYSINT_MAX(t)							\
+	((((t) 1 << (sizeof(t) * 8 - 2)) - (t) 1) * (t) 2 + (t) 1)
+
+int bch_strtoint_h(const char *cp, int *res);
+int bch_strtouint_h(const char *cp, unsigned int *res);
+int bch_strtoll_h(const char *cp, long long *res);
+int bch_strtoull_h(const char *cp, unsigned long long *res);
+
+static inline int bch_strtol_h(const char *cp, long *res)
+{
+#if BITS_PER_LONG == 32
+	return bch_strtoint_h(cp, (int *) res);
+#else
+	return bch_strtoll_h(cp, (long long *) res);
+#endif
+}
+
+static inline int bch_strtoul_h(const char *cp, long *res)
+{
+#if BITS_PER_LONG == 32
+	return bch_strtouint_h(cp, (unsigned int *) res);
+#else
+	return bch_strtoull_h(cp, (unsigned long long *) res);
+#endif
+}
+
+#define strtoi_h(cp, res)						\
+	(__builtin_types_compatible_p(typeof(*res), int)		\
+	? bch_strtoint_h(cp, (void *) res)				\
+	: __builtin_types_compatible_p(typeof(*res), long)		\
+	? bch_strtol_h(cp, (void *) res)				\
+	: __builtin_types_compatible_p(typeof(*res), long long)		\
+	? bch_strtoll_h(cp, (void *) res)				\
+	: __builtin_types_compatible_p(typeof(*res), unsigned int)	\
+	? bch_strtouint_h(cp, (void *) res)				\
+	: __builtin_types_compatible_p(typeof(*res), unsigned long)	\
+	? bch_strtoul_h(cp, (void *) res)				\
+	: __builtin_types_compatible_p(typeof(*res), unsigned long long)\
+	? bch_strtoull_h(cp, (void *) res) : -EINVAL)
+
+#define strtoul_safe(cp, var)						\
+({									\
+	unsigned long _v;						\
+	int _r = kstrtoul(cp, 10, &_v);					\
+	if (!_r)							\
+		var = _v;						\
+	_r;								\
+})
+
+#define strtoul_safe_clamp(cp, var, min, max)				\
+({									\
+	unsigned long _v;						\
+	int _r = kstrtoul(cp, 10, &_v);					\
+	if (!_r)							\
+		var = clamp_t(typeof(var), _v, min, max);		\
+	_r;								\
+})
+
+ssize_t bch_hprint(char *buf, int64_t v);
+
+bool bch_is_zero(const char *p, size_t n);
+int bch_parse_uuid(const char *s, char *uuid);
+
+struct time_stats {
+	spinlock_t	lock;
+	/*
+	 * all fields are in nanoseconds, averages are ewmas stored left shifted
+	 * by 8
+	 */
+	uint64_t	max_duration;
+	uint64_t	average_duration;
+	uint64_t	average_frequency;
+	uint64_t	last;
+};
+
+void bch_time_stats_update(struct time_stats *stats, uint64_t time);
+
+static inline unsigned int local_clock_us(void)
+{
+	return local_clock() >> 10;
+}
+
+#define NSEC_PER_ns			1L
+#define NSEC_PER_us			NSEC_PER_USEC
+#define NSEC_PER_ms			NSEC_PER_MSEC
+#define NSEC_PER_sec			NSEC_PER_SEC
+
+#define __print_time_stat(stats, name, stat, units)			\
+	sysfs_print(name ## _ ## stat ## _ ## units,			\
+		    div_u64((stats)->stat >> 8, NSEC_PER_ ## units))
+
+#define sysfs_print_time_stats(stats, name,				\
+			       frequency_units,				\
+			       duration_units)				\
+do {									\
+	__print_time_stat(stats, name,					\
+			  average_frequency,	frequency_units);	\
+	__print_time_stat(stats, name,					\
+			  average_duration,	duration_units);	\
+	sysfs_print(name ## _ ##max_duration ## _ ## duration_units,	\
+			div_u64((stats)->max_duration,			\
+				NSEC_PER_ ## duration_units));		\
+									\
+	sysfs_print(name ## _last_ ## frequency_units, (stats)->last	\
+		    ? div_s64(local_clock() - (stats)->last,		\
+			      NSEC_PER_ ## frequency_units)		\
+		    : -1LL);						\
+} while (0)
+
+#define sysfs_time_stats_attribute(name,				\
+				   frequency_units,			\
+				   duration_units)			\
+read_attribute(name ## _average_frequency_ ## frequency_units);		\
+read_attribute(name ## _average_duration_ ## duration_units);		\
+read_attribute(name ## _max_duration_ ## duration_units);		\
+read_attribute(name ## _last_ ## frequency_units)
+
+#define sysfs_time_stats_attribute_list(name,				\
+					frequency_units,		\
+					duration_units)			\
+&sysfs_ ## name ## _average_frequency_ ## frequency_units,		\
+&sysfs_ ## name ## _average_duration_ ## duration_units,		\
+&sysfs_ ## name ## _max_duration_ ## duration_units,			\
+&sysfs_ ## name ## _last_ ## frequency_units,
+
+#define ewma_add(ewma, val, weight, factor)				\
+({									\
+	(ewma) *= (weight) - 1;						\
+	(ewma) += (val) << factor;					\
+	(ewma) /= (weight);						\
+	(ewma) >> factor;						\
+})
+
+struct bch_ratelimit {
+	/* Next time we want to do some work, in nanoseconds */
+	uint64_t		next;
+
+	/*
+	 * Rate at which we want to do work, in units per second
+	 * The units here correspond to the units passed to bch_next_delay()
+	 */
+	atomic_long_t		rate;
+};
+
+static inline void bch_ratelimit_reset(struct bch_ratelimit *d)
+{
+	d->next = local_clock();
+}
+
+uint64_t bch_next_delay(struct bch_ratelimit *d, uint64_t done);
+
+#define __DIV_SAFE(n, d, zero)						\
+({									\
+	typeof(n) _n = (n);						\
+	typeof(d) _d = (d);						\
+	_d ? _n / _d : zero;						\
+})
+
+#define DIV_SAFE(n, d)	__DIV_SAFE(n, d, 0)
+
+#define container_of_or_null(ptr, type, member)				\
+({									\
+	typeof(ptr) _ptr = ptr;						\
+	_ptr ? container_of(_ptr, type, member) : NULL;			\
+})
+
+#define RB_INSERT(root, new, member, cmp)				\
+({									\
+	__label__ dup;							\
+	struct rb_node **n = &(root)->rb_node, *parent = NULL;		\
+	typeof(new) this;						\
+	int res, ret = -1;						\
+									\
+	while (*n) {							\
+		parent = *n;						\
+		this = container_of(*n, typeof(*(new)), member);	\
+		res = cmp(new, this);					\
+		if (!res)						\
+			goto dup;					\
+		n = res < 0						\
+			? &(*n)->rb_left				\
+			: &(*n)->rb_right;				\
+	}								\
+									\
+	rb_link_node(&(new)->member, parent, n);			\
+	rb_insert_color(&(new)->member, root);				\
+	ret = 0;							\
+dup:									\
+	ret;								\
+})
+
+#define RB_SEARCH(root, search, member, cmp)				\
+({									\
+	struct rb_node *n = (root)->rb_node;				\
+	typeof(&(search)) this, ret = NULL;				\
+	int res;							\
+									\
+	while (n) {							\
+		this = container_of(n, typeof(search), member);		\
+		res = cmp(&(search), this);				\
+		if (!res) {						\
+			ret = this;					\
+			break;						\
+		}							\
+		n = res < 0						\
+			? n->rb_left					\
+			: n->rb_right;					\
+	}								\
+	ret;								\
+})
+
+#define RB_GREATER(root, search, member, cmp)				\
+({									\
+	struct rb_node *n = (root)->rb_node;				\
+	typeof(&(search)) this, ret = NULL;				\
+	int res;							\
+									\
+	while (n) {							\
+		this = container_of(n, typeof(search), member);		\
+		res = cmp(&(search), this);				\
+		if (res < 0) {						\
+			ret = this;					\
+			n = n->rb_left;					\
+		} else							\
+			n = n->rb_right;				\
+	}								\
+	ret;								\
+})
+
+#define RB_FIRST(root, type, member)					\
+	container_of_or_null(rb_first(root), type, member)
+
+#define RB_LAST(root, type, member)					\
+	container_of_or_null(rb_last(root), type, member)
+
+#define RB_NEXT(ptr, member)						\
+	container_of_or_null(rb_next(&(ptr)->member), typeof(*ptr), member)
+
+#define RB_PREV(ptr, member)						\
+	container_of_or_null(rb_prev(&(ptr)->member), typeof(*ptr), member)
+
+static inline uint64_t bch_crc64(const void *p, size_t len)
+{
+	uint64_t crc = 0xffffffffffffffffULL;
+
+	crc = crc64_be(crc, p, len);
+	return crc ^ 0xffffffffffffffffULL;
+}
+
+/*
+ * A stepwise-linear pseudo-exponential.  This returns 1 << (x >>
+ * frac_bits), with the less-significant bits filled in by linear
+ * interpolation.
+ *
+ * This can also be interpreted as a floating-point number format,
+ * where the low frac_bits are the mantissa (with implicit leading
+ * 1 bit), and the more significant bits are the exponent.
+ * The return value is 1.mantissa * 2^exponent.
+ *
+ * The way this is used, fract_bits is 6 and the largest possible
+ * input is CONGESTED_MAX-1 = 1023 (exponent 16, mantissa 0x1.fc),
+ * so the maximum output is 0x1fc00.
+ */
+static inline unsigned int fract_exp_two(unsigned int x,
+					 unsigned int fract_bits)
+{
+	unsigned int mantissa = 1 << fract_bits;	/* Implicit bit */
+
+	mantissa += x & (mantissa - 1);
+	x >>= fract_bits;	/* The exponent */
+	/* Largest intermediate value 0x7f0000 */
+	return mantissa << x >> fract_bits;
+}
+
+void bch_bio_map(struct bio *bio, void *base);
+int bch_bio_alloc_pages(struct bio *bio, gfp_t gfp_mask);
+
+#endif /* _BCACHE_UTIL_H */

linux-7.2.3/drivers/md/bcache/writeback.h

@@ -0,0 +1,155 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_WRITEBACK_H
+#define _BCACHE_WRITEBACK_H
+
+#define CUTOFF_WRITEBACK	40
+#define CUTOFF_WRITEBACK_SYNC	70
+
+#define CUTOFF_WRITEBACK_MAX		70
+#define CUTOFF_WRITEBACK_SYNC_MAX	90
+
+#define MAX_WRITEBACKS_IN_PASS  5
+#define MAX_WRITESIZE_IN_PASS   5000	/* *512b */
+
+#define WRITEBACK_RATE_UPDATE_SECS_MAX		60
+#define WRITEBACK_RATE_UPDATE_SECS_DEFAULT	5
+
+#define BCH_AUTO_GC_DIRTY_THRESHOLD	50
+
+#define BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW 50
+#define BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID 57
+#define BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH 64
+
+#define BCH_DIRTY_INIT_THRD_MAX	12
+/*
+ * 14 (16384ths) is chosen here as something that each backing device
+ * should be a reasonable fraction of the share, and not to blow up
+ * until individual backing devices are a petabyte.
+ */
+#define WRITEBACK_SHARE_SHIFT   14
+
+struct bch_dirty_init_state;
+struct dirty_init_thrd_info {
+	struct bch_dirty_init_state	*state;
+	struct task_struct		*thread;
+};
+
+struct bch_dirty_init_state {
+	struct cache_set		*c;
+	struct bcache_device		*d;
+	int				total_threads;
+	int				key_idx;
+	spinlock_t			idx_lock;
+	atomic_t			started;
+	atomic_t			enough;
+	wait_queue_head_t		wait;
+	struct dirty_init_thrd_info	infos[BCH_DIRTY_INIT_THRD_MAX];
+};
+
+static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
+{
+	uint64_t i, ret = 0;
+
+	for (i = 0; i < d->nr_stripes; i++)
+		ret += atomic_read(d->stripe_sectors_dirty + i);
+
+	return ret;
+}
+
+static inline int offset_to_stripe(struct bcache_device *d,
+					uint64_t offset)
+{
+	do_div(offset, d->stripe_size);
+
+	/* d->nr_stripes is in range [1, INT_MAX] */
+	if (unlikely(offset >= d->nr_stripes)) {
+		pr_err("Invalid stripe %llu (>= nr_stripes %d).\n",
+			offset, d->nr_stripes);
+		return -EINVAL;
+	}
+
+	/*
+	 * Here offset is definitly smaller than INT_MAX,
+	 * return it as int will never overflow.
+	 */
+	return offset;
+}
+
+static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
+					   uint64_t offset,
+					   unsigned int nr_sectors)
+{
+	int stripe = offset_to_stripe(&dc->disk, offset);
+
+	if (stripe < 0)
+		return false;
+
+	while (1) {
+		if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
+			return true;
+
+		if (nr_sectors <= dc->disk.stripe_size)
+			return false;
+
+		nr_sectors -= dc->disk.stripe_size;
+		stripe++;
+	}
+}
+
+extern unsigned int bch_cutoff_writeback;
+extern unsigned int bch_cutoff_writeback_sync;
+
+static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
+				    unsigned int cache_mode, bool would_skip)
+{
+	unsigned int in_use = dc->disk.c->gc_stats.in_use;
+
+	if (cache_mode != CACHE_MODE_WRITEBACK ||
+	    test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
+	    in_use > bch_cutoff_writeback_sync)
+		return false;
+
+	if (bio_op(bio) == REQ_OP_DISCARD)
+		return false;
+
+	if (dc->partial_stripes_expensive &&
+	    bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
+				    bio_sectors(bio)))
+		return true;
+
+	if (would_skip)
+		return false;
+
+	return (op_is_sync(bio->bi_opf) ||
+		bio->bi_opf & (REQ_META|REQ_PRIO) ||
+		in_use <= bch_cutoff_writeback);
+}
+
+static inline void bch_writeback_queue(struct cached_dev *dc)
+{
+	if (!IS_ERR_OR_NULL(dc->writeback_thread))
+		wake_up_process(dc->writeback_thread);
+}
+
+static inline void bch_writeback_add(struct cached_dev *dc)
+{
+	if (!atomic_read(&dc->has_dirty) &&
+	    !atomic_xchg(&dc->has_dirty, 1)) {
+		if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
+			SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
+			/* XXX: should do this synchronously */
+			bch_write_bdev_super(dc, NULL);
+		}
+
+		bch_writeback_queue(dc);
+	}
+}
+
+void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
+				  uint64_t offset, int nr_sectors);
+
+void bch_sectors_dirty_init(struct bcache_device *d);
+void bch_cached_dev_writeback_init(struct cached_dev *dc);
+int bch_cached_dev_writeback_start(struct cached_dev *dc);
+
+#endif