Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 923 insertions, 0 deletions

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
new file mode 100644
index 000000000..144693b7c
--- /dev/null
+++ b/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;
+}