Adding upstream version 6.7.7.upstream/6.7.7

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1439 insertions, 0 deletions

diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
new file mode 100644
index 0000000000..8cf238be62
--- /dev/null
+++ b/fs/bcachefs/journal.c
@@ -0,0 +1,1439 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * bcachefs journalling code, for btree insertions
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcachefs.h"
+#include "alloc_foreground.h"
+#include "bkey_methods.h"
+#include "btree_gc.h"
+#include "btree_update.h"
+#include "buckets.h"
+#include "error.h"
+#include "journal.h"
+#include "journal_io.h"
+#include "journal_reclaim.h"
+#include "journal_sb.h"
+#include "journal_seq_blacklist.h"
+#include "trace.h"
+
+static const char * const bch2_journal_errors[] = {
+#define x(n)	#n,
+	JOURNAL_ERRORS()
+#undef x
+	NULL
+};
+
+static inline bool journal_seq_unwritten(struct journal *j, u64 seq)
+{
+	return seq > j->seq_ondisk;
+}
+
+static bool __journal_entry_is_open(union journal_res_state state)
+{
+	return state.cur_entry_offset < JOURNAL_ENTRY_CLOSED_VAL;
+}
+
+static inline unsigned nr_unwritten_journal_entries(struct journal *j)
+{
+	return atomic64_read(&j->seq) - j->seq_ondisk;
+}
+
+static bool journal_entry_is_open(struct journal *j)
+{
+	return __journal_entry_is_open(j->reservations);
+}
+
+static inline struct journal_buf *
+journal_seq_to_buf(struct journal *j, u64 seq)
+{
+	struct journal_buf *buf = NULL;
+
+	EBUG_ON(seq > journal_cur_seq(j));
+
+	if (journal_seq_unwritten(j, seq)) {
+		buf = j->buf + (seq & JOURNAL_BUF_MASK);
+		EBUG_ON(le64_to_cpu(buf->data->seq) != seq);
+	}
+	return buf;
+}
+
+static void journal_pin_list_init(struct journal_entry_pin_list *p, int count)
+{
+	unsigned i;
+
+	for (i = 0; i < ARRAY_SIZE(p->list); i++)
+		INIT_LIST_HEAD(&p->list[i]);
+	INIT_LIST_HEAD(&p->flushed);
+	atomic_set(&p->count, count);
+	p->devs.nr = 0;
+}
+
+/*
+ * Detect stuck journal conditions and trigger shutdown. Technically the journal
+ * can end up stuck for a variety of reasons, such as a blocked I/O, journal
+ * reservation lockup, etc. Since this is a fatal error with potentially
+ * unpredictable characteristics, we want to be fairly conservative before we
+ * decide to shut things down.
+ *
+ * Consider the journal stuck when it appears full with no ability to commit
+ * btree transactions, to discard journal buckets, nor acquire priority
+ * (reserved watermark) reservation.
+ */
+static inline bool
+journal_error_check_stuck(struct journal *j, int error, unsigned flags)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	bool stuck = false;
+	struct printbuf buf = PRINTBUF;
+
+	if (!(error == JOURNAL_ERR_journal_full ||
+	      error == JOURNAL_ERR_journal_pin_full) ||
+	    nr_unwritten_journal_entries(j) ||
+	    (flags & BCH_WATERMARK_MASK) != BCH_WATERMARK_reclaim)
+		return stuck;
+
+	spin_lock(&j->lock);
+
+	if (j->can_discard) {
+		spin_unlock(&j->lock);
+		return stuck;
+	}
+
+	stuck = true;
+
+	/*
+	 * The journal shutdown path will set ->err_seq, but do it here first to
+	 * serialize against concurrent failures and avoid duplicate error
+	 * reports.
+	 */
+	if (j->err_seq) {
+		spin_unlock(&j->lock);
+		return stuck;
+	}
+	j->err_seq = journal_cur_seq(j);
+	spin_unlock(&j->lock);
+
+	bch_err(c, "Journal stuck! Hava a pre-reservation but journal full (error %s)",
+		bch2_journal_errors[error]);
+	bch2_journal_debug_to_text(&buf, j);
+	bch_err(c, "%s", buf.buf);
+
+	printbuf_reset(&buf);
+	bch2_journal_pins_to_text(&buf, j);
+	bch_err(c, "Journal pins:\n%s", buf.buf);
+	printbuf_exit(&buf);
+
+	bch2_fatal_error(c);
+	dump_stack();
+
+	return stuck;
+}
+
+/*
+ * Final processing when the last reference of a journal buffer has been
+ * dropped. Drop the pin list reference acquired at journal entry open and write
+ * the buffer, if requested.
+ */
+void bch2_journal_buf_put_final(struct journal *j, u64 seq, bool write)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+
+	lockdep_assert_held(&j->lock);
+
+	if (__bch2_journal_pin_put(j, seq))
+		bch2_journal_reclaim_fast(j);
+	if (write)
+		closure_call(&j->io, bch2_journal_write, c->io_complete_wq, NULL);
+}
+
+/*
+ * Returns true if journal entry is now closed:
+ *
+ * We don't close a journal_buf until the next journal_buf is finished writing,
+ * and can be opened again - this also initializes the next journal_buf:
+ */
+static void __journal_entry_close(struct journal *j, unsigned closed_val)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	struct journal_buf *buf = journal_cur_buf(j);
+	union journal_res_state old, new;
+	u64 v = atomic64_read(&j->reservations.counter);
+	unsigned sectors;
+
+	BUG_ON(closed_val != JOURNAL_ENTRY_CLOSED_VAL &&
+	       closed_val != JOURNAL_ENTRY_ERROR_VAL);
+
+	lockdep_assert_held(&j->lock);
+
+	do {
+		old.v = new.v = v;
+		new.cur_entry_offset = closed_val;
+
+		if (old.cur_entry_offset == JOURNAL_ENTRY_ERROR_VAL ||
+		    old.cur_entry_offset == new.cur_entry_offset)
+			return;
+	} while ((v = atomic64_cmpxchg(&j->reservations.counter,
+				       old.v, new.v)) != old.v);
+
+	if (!__journal_entry_is_open(old))
+		return;
+
+	/* Close out old buffer: */
+	buf->data->u64s		= cpu_to_le32(old.cur_entry_offset);
+
+	sectors = vstruct_blocks_plus(buf->data, c->block_bits,
+				      buf->u64s_reserved) << c->block_bits;
+	BUG_ON(sectors > buf->sectors);
+	buf->sectors = sectors;
+
+	/*
+	 * We have to set last_seq here, _before_ opening a new journal entry:
+	 *
+	 * A threads may replace an old pin with a new pin on their current
+	 * journal reservation - the expectation being that the journal will
+	 * contain either what the old pin protected or what the new pin
+	 * protects.
+	 *
+	 * After the old pin is dropped journal_last_seq() won't include the old
+	 * pin, so we can only write the updated last_seq on the entry that
+	 * contains whatever the new pin protects.
+	 *
+	 * Restated, we can _not_ update last_seq for a given entry if there
+	 * could be a newer entry open with reservations/pins that have been
+	 * taken against it.
+	 *
+	 * Hence, we want update/set last_seq on the current journal entry right
+	 * before we open a new one:
+	 */
+	buf->last_seq		= journal_last_seq(j);
+	buf->data->last_seq	= cpu_to_le64(buf->last_seq);
+	BUG_ON(buf->last_seq > le64_to_cpu(buf->data->seq));
+
+	cancel_delayed_work(&j->write_work);
+
+	bch2_journal_space_available(j);
+
+	__bch2_journal_buf_put(j, old.idx, le64_to_cpu(buf->data->seq));
+}
+
+void bch2_journal_halt(struct journal *j)
+{
+	spin_lock(&j->lock);
+	__journal_entry_close(j, JOURNAL_ENTRY_ERROR_VAL);
+	if (!j->err_seq)
+		j->err_seq = journal_cur_seq(j);
+	journal_wake(j);
+	spin_unlock(&j->lock);
+}
+
+static bool journal_entry_want_write(struct journal *j)
+{
+	bool ret = !journal_entry_is_open(j) ||
+		journal_cur_seq(j) == journal_last_unwritten_seq(j);
+
+	/* Don't close it yet if we already have a write in flight: */
+	if (ret)
+		__journal_entry_close(j, JOURNAL_ENTRY_CLOSED_VAL);
+	else if (nr_unwritten_journal_entries(j)) {
+		struct journal_buf *buf = journal_cur_buf(j);
+
+		if (!buf->flush_time) {
+			buf->flush_time	= local_clock() ?: 1;
+			buf->expires = jiffies;
+		}
+	}
+
+	return ret;
+}
+
+bool bch2_journal_entry_close(struct journal *j)
+{
+	bool ret;
+
+	spin_lock(&j->lock);
+	ret = journal_entry_want_write(j);
+	spin_unlock(&j->lock);
+
+	return ret;
+}
+
+/*
+ * should _only_ called from journal_res_get() - when we actually want a
+ * journal reservation - journal entry is open means journal is dirty:
+ */
+static int journal_entry_open(struct journal *j)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	struct journal_buf *buf = j->buf +
+		((journal_cur_seq(j) + 1) & JOURNAL_BUF_MASK);
+	union journal_res_state old, new;
+	int u64s;
+	u64 v;
+
+	lockdep_assert_held(&j->lock);
+	BUG_ON(journal_entry_is_open(j));
+	BUG_ON(BCH_SB_CLEAN(c->disk_sb.sb));
+
+	if (j->blocked)
+		return JOURNAL_ERR_blocked;
+
+	if (j->cur_entry_error)
+		return j->cur_entry_error;
+
+	if (bch2_journal_error(j))
+		return JOURNAL_ERR_insufficient_devices; /* -EROFS */
+
+	if (!fifo_free(&j->pin))
+		return JOURNAL_ERR_journal_pin_full;
+
+	if (nr_unwritten_journal_entries(j) == ARRAY_SIZE(j->buf))
+		return JOURNAL_ERR_max_in_flight;
+
+	BUG_ON(!j->cur_entry_sectors);
+
+	buf->expires		=
+		(journal_cur_seq(j) == j->flushed_seq_ondisk
+		 ? jiffies
+		 : j->last_flush_write) +
+		msecs_to_jiffies(c->opts.journal_flush_delay);
+
+	buf->u64s_reserved	= j->entry_u64s_reserved;
+	buf->disk_sectors	= j->cur_entry_sectors;
+	buf->sectors		= min(buf->disk_sectors, buf->buf_size >> 9);
+
+	u64s = (int) (buf->sectors << 9) / sizeof(u64) -
+		journal_entry_overhead(j);
+	u64s = clamp_t(int, u64s, 0, JOURNAL_ENTRY_CLOSED_VAL - 1);
+
+	if (u64s <= (ssize_t) j->early_journal_entries.nr)
+		return JOURNAL_ERR_journal_full;
+
+	if (fifo_empty(&j->pin) && j->reclaim_thread)
+		wake_up_process(j->reclaim_thread);
+
+	/*
+	 * The fifo_push() needs to happen at the same time as j->seq is
+	 * incremented for journal_last_seq() to be calculated correctly
+	 */
+	atomic64_inc(&j->seq);
+	journal_pin_list_init(fifo_push_ref(&j->pin), 1);
+
+	BUG_ON(j->pin.back - 1 != atomic64_read(&j->seq));
+
+	BUG_ON(j->buf + (journal_cur_seq(j) & JOURNAL_BUF_MASK) != buf);
+
+	bkey_extent_init(&buf->key);
+	buf->noflush	= false;
+	buf->must_flush	= false;
+	buf->separate_flush = false;
+	buf->flush_time	= 0;
+
+	memset(buf->data, 0, sizeof(*buf->data));
+	buf->data->seq	= cpu_to_le64(journal_cur_seq(j));
+	buf->data->u64s	= 0;
+
+	if (j->early_journal_entries.nr) {
+		memcpy(buf->data->_data, j->early_journal_entries.data,
+		       j->early_journal_entries.nr * sizeof(u64));
+		le32_add_cpu(&buf->data->u64s, j->early_journal_entries.nr);
+	}
+
+	/*
+	 * Must be set before marking the journal entry as open:
+	 */
+	j->cur_entry_u64s = u64s;
+
+	v = atomic64_read(&j->reservations.counter);
+	do {
+		old.v = new.v = v;
+
+		BUG_ON(old.cur_entry_offset == JOURNAL_ENTRY_ERROR_VAL);
+
+		new.idx++;
+		BUG_ON(journal_state_count(new, new.idx));
+		BUG_ON(new.idx != (journal_cur_seq(j) & JOURNAL_BUF_MASK));
+
+		journal_state_inc(&new);
+
+		/* Handle any already added entries */
+		new.cur_entry_offset = le32_to_cpu(buf->data->u64s);
+	} while ((v = atomic64_cmpxchg(&j->reservations.counter,
+				       old.v, new.v)) != old.v);
+
+	if (j->res_get_blocked_start)
+		bch2_time_stats_update(j->blocked_time,
+				       j->res_get_blocked_start);
+	j->res_get_blocked_start = 0;
+
+	mod_delayed_work(c->io_complete_wq,
+			 &j->write_work,
+			 msecs_to_jiffies(c->opts.journal_flush_delay));
+	journal_wake(j);
+
+	if (j->early_journal_entries.nr)
+		darray_exit(&j->early_journal_entries);
+	return 0;
+}
+
+static bool journal_quiesced(struct journal *j)
+{
+	bool ret = atomic64_read(&j->seq) == j->seq_ondisk;
+
+	if (!ret)
+		bch2_journal_entry_close(j);
+	return ret;
+}
+
+static void journal_quiesce(struct journal *j)
+{
+	wait_event(j->wait, journal_quiesced(j));
+}
+
+static void journal_write_work(struct work_struct *work)
+{
+	struct journal *j = container_of(work, struct journal, write_work.work);
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	long delta;
+
+	spin_lock(&j->lock);
+	if (!__journal_entry_is_open(j->reservations))
+		goto unlock;
+
+	delta = journal_cur_buf(j)->expires - jiffies;
+
+	if (delta > 0)
+		mod_delayed_work(c->io_complete_wq, &j->write_work, delta);
+	else
+		__journal_entry_close(j, JOURNAL_ENTRY_CLOSED_VAL);
+unlock:
+	spin_unlock(&j->lock);
+}
+
+static int __journal_res_get(struct journal *j, struct journal_res *res,
+			     unsigned flags)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	struct journal_buf *buf;
+	bool can_discard;
+	int ret;
+retry:
+	if (journal_res_get_fast(j, res, flags))
+		return 0;
+
+	if (bch2_journal_error(j))
+		return -BCH_ERR_erofs_journal_err;
+
+	spin_lock(&j->lock);
+
+	/* check once more in case somebody else shut things down... */
+	if (bch2_journal_error(j)) {
+		spin_unlock(&j->lock);
+		return -BCH_ERR_erofs_journal_err;
+	}
+
+	/*
+	 * Recheck after taking the lock, so we don't race with another thread
+	 * that just did journal_entry_open() and call bch2_journal_entry_close()
+	 * unnecessarily
+	 */
+	if (journal_res_get_fast(j, res, flags)) {
+		spin_unlock(&j->lock);
+		return 0;
+	}
+
+	if ((flags & BCH_WATERMARK_MASK) < j->watermark) {
+		/*
+		 * Don't want to close current journal entry, just need to
+		 * invoke reclaim:
+		 */
+		ret = JOURNAL_ERR_journal_full;
+		goto unlock;
+	}
+
+	/*
+	 * If we couldn't get a reservation because the current buf filled up,
+	 * and we had room for a bigger entry on disk, signal that we want to
+	 * realloc the journal bufs:
+	 */
+	buf = journal_cur_buf(j);
+	if (journal_entry_is_open(j) &&
+	    buf->buf_size >> 9 < buf->disk_sectors &&
+	    buf->buf_size < JOURNAL_ENTRY_SIZE_MAX)
+		j->buf_size_want = max(j->buf_size_want, buf->buf_size << 1);
+
+	__journal_entry_close(j, JOURNAL_ENTRY_CLOSED_VAL);
+	ret = journal_entry_open(j);
+
+	if (ret == JOURNAL_ERR_max_in_flight)
+		trace_and_count(c, journal_entry_full, c);
+unlock:
+	if ((ret && ret != JOURNAL_ERR_insufficient_devices) &&
+	    !j->res_get_blocked_start) {
+		j->res_get_blocked_start = local_clock() ?: 1;
+		trace_and_count(c, journal_full, c);
+	}
+
+	can_discard = j->can_discard;
+	spin_unlock(&j->lock);
+
+	if (!ret)
+		goto retry;
+	if (journal_error_check_stuck(j, ret, flags))
+		ret = -BCH_ERR_journal_res_get_blocked;
+
+	/*
+	 * Journal is full - can't rely on reclaim from work item due to
+	 * freezing:
+	 */
+	if ((ret == JOURNAL_ERR_journal_full ||
+	     ret == JOURNAL_ERR_journal_pin_full) &&
+	    !(flags & JOURNAL_RES_GET_NONBLOCK)) {
+		if (can_discard) {
+			bch2_journal_do_discards(j);
+			goto retry;
+		}
+
+		if (mutex_trylock(&j->reclaim_lock)) {
+			bch2_journal_reclaim(j);
+			mutex_unlock(&j->reclaim_lock);
+		}
+	}
+
+	return ret == JOURNAL_ERR_insufficient_devices
+		? -BCH_ERR_erofs_journal_err
+		: -BCH_ERR_journal_res_get_blocked;
+}
+
+/*
+ * Essentially the entry function to the journaling code. When bcachefs is doing
+ * a btree insert, it calls this function to get the current journal write.
+ * Journal write is the structure used set up journal writes. The calling
+ * function will then add its keys to the structure, queuing them for the next
+ * write.
+ *
+ * To ensure forward progress, the current task must not be holding any
+ * btree node write locks.
+ */
+int bch2_journal_res_get_slowpath(struct journal *j, struct journal_res *res,
+				  unsigned flags)
+{
+	int ret;
+
+	closure_wait_event(&j->async_wait,
+		   (ret = __journal_res_get(j, res, flags)) != -BCH_ERR_journal_res_get_blocked ||
+		   (flags & JOURNAL_RES_GET_NONBLOCK));
+	return ret;
+}
+
+/* journal_entry_res: */
+
+void bch2_journal_entry_res_resize(struct journal *j,
+				   struct journal_entry_res *res,
+				   unsigned new_u64s)
+{
+	union journal_res_state state;
+	int d = new_u64s - res->u64s;
+
+	spin_lock(&j->lock);
+
+	j->entry_u64s_reserved += d;
+	if (d <= 0)
+		goto out;
+
+	j->cur_entry_u64s = max_t(int, 0, j->cur_entry_u64s - d);
+	smp_mb();
+	state = READ_ONCE(j->reservations);
+
+	if (state.cur_entry_offset < JOURNAL_ENTRY_CLOSED_VAL &&
+	    state.cur_entry_offset > j->cur_entry_u64s) {
+		j->cur_entry_u64s += d;
+		/*
+		 * Not enough room in current journal entry, have to flush it:
+		 */
+		__journal_entry_close(j, JOURNAL_ENTRY_CLOSED_VAL);
+	} else {
+		journal_cur_buf(j)->u64s_reserved += d;
+	}
+out:
+	spin_unlock(&j->lock);
+	res->u64s += d;
+}
+
+/* journal flushing: */
+
+/**
+ * bch2_journal_flush_seq_async - wait for a journal entry to be written
+ * @j:		journal object
+ * @seq:	seq to flush
+ * @parent:	closure object to wait with
+ * Returns:	1 if @seq has already been flushed, 0 if @seq is being flushed,
+ *		-EIO if @seq will never be flushed
+ *
+ * Like bch2_journal_wait_on_seq, except that it triggers a write immediately if
+ * necessary
+ */
+int bch2_journal_flush_seq_async(struct journal *j, u64 seq,
+				 struct closure *parent)
+{
+	struct journal_buf *buf;
+	int ret = 0;
+
+	if (seq <= j->flushed_seq_ondisk)
+		return 1;
+
+	spin_lock(&j->lock);
+
+	if (WARN_ONCE(seq > journal_cur_seq(j),
+		      "requested to flush journal seq %llu, but currently at %llu",
+		      seq, journal_cur_seq(j)))
+		goto out;
+
+	/* Recheck under lock: */
+	if (j->err_seq && seq >= j->err_seq) {
+		ret = -EIO;
+		goto out;
+	}
+
+	if (seq <= j->flushed_seq_ondisk) {
+		ret = 1;
+		goto out;
+	}
+
+	/* if seq was written, but not flushed - flush a newer one instead */
+	seq = max(seq, journal_last_unwritten_seq(j));
+
+recheck_need_open:
+	if (seq > journal_cur_seq(j)) {
+		struct journal_res res = { 0 };
+
+		if (journal_entry_is_open(j))
+			__journal_entry_close(j, JOURNAL_ENTRY_CLOSED_VAL);
+
+		spin_unlock(&j->lock);
+
+		ret = bch2_journal_res_get(j, &res, jset_u64s(0), 0);
+		if (ret)
+			return ret;
+
+		seq = res.seq;
+		buf = j->buf + (seq & JOURNAL_BUF_MASK);
+		buf->must_flush = true;
+
+		if (!buf->flush_time) {
+			buf->flush_time	= local_clock() ?: 1;
+			buf->expires = jiffies;
+		}
+
+		if (parent && !closure_wait(&buf->wait, parent))
+			BUG();
+
+		bch2_journal_res_put(j, &res);
+
+		spin_lock(&j->lock);
+		goto want_write;
+	}
+
+	/*
+	 * if write was kicked off without a flush, flush the next sequence
+	 * number instead
+	 */
+	buf = journal_seq_to_buf(j, seq);
+	if (buf->noflush) {
+		seq++;
+		goto recheck_need_open;
+	}
+
+	buf->must_flush = true;
+
+	if (parent && !closure_wait(&buf->wait, parent))
+		BUG();
+want_write:
+	if (seq == journal_cur_seq(j))
+		journal_entry_want_write(j);
+out:
+	spin_unlock(&j->lock);
+	return ret;
+}
+
+int bch2_journal_flush_seq(struct journal *j, u64 seq)
+{
+	u64 start_time = local_clock();
+	int ret, ret2;
+
+	/*
+	 * Don't update time_stats when @seq is already flushed:
+	 */
+	if (seq <= j->flushed_seq_ondisk)
+		return 0;
+
+	ret = wait_event_interruptible(j->wait, (ret2 = bch2_journal_flush_seq_async(j, seq, NULL)));
+
+	if (!ret)
+		bch2_time_stats_update(j->flush_seq_time, start_time);
+
+	return ret ?: ret2 < 0 ? ret2 : 0;
+}
+
+/*
+ * bch2_journal_flush_async - if there is an open journal entry, or a journal
+ * still being written, write it and wait for the write to complete
+ */
+void bch2_journal_flush_async(struct journal *j, struct closure *parent)
+{
+	bch2_journal_flush_seq_async(j, atomic64_read(&j->seq), parent);
+}
+
+int bch2_journal_flush(struct journal *j)
+{
+	return bch2_journal_flush_seq(j, atomic64_read(&j->seq));
+}
+
+/*
+ * bch2_journal_noflush_seq - tell the journal not to issue any flushes before
+ * @seq
+ */
+bool bch2_journal_noflush_seq(struct journal *j, u64 seq)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	u64 unwritten_seq;
+	bool ret = false;
+
+	if (!(c->sb.features & (1ULL << BCH_FEATURE_journal_no_flush)))
+		return false;
+
+	if (seq <= c->journal.flushed_seq_ondisk)
+		return false;
+
+	spin_lock(&j->lock);
+	if (seq <= c->journal.flushed_seq_ondisk)
+		goto out;
+
+	for (unwritten_seq = journal_last_unwritten_seq(j);
+	     unwritten_seq < seq;
+	     unwritten_seq++) {
+		struct journal_buf *buf = journal_seq_to_buf(j, unwritten_seq);
+
+		/* journal write is already in flight, and was a flush write: */
+		if (unwritten_seq == journal_last_unwritten_seq(j) && !buf->noflush)
+			goto out;
+
+		buf->noflush = true;
+	}
+
+	ret = true;
+out:
+	spin_unlock(&j->lock);
+	return ret;
+}
+
+int bch2_journal_meta(struct journal *j)
+{
+	struct journal_buf *buf;
+	struct journal_res res;
+	int ret;
+
+	memset(&res, 0, sizeof(res));
+
+	ret = bch2_journal_res_get(j, &res, jset_u64s(0), 0);
+	if (ret)
+		return ret;
+
+	buf = j->buf + (res.seq & JOURNAL_BUF_MASK);
+	buf->must_flush = true;
+
+	if (!buf->flush_time) {
+		buf->flush_time	= local_clock() ?: 1;
+		buf->expires = jiffies;
+	}
+
+	bch2_journal_res_put(j, &res);
+
+	return bch2_journal_flush_seq(j, res.seq);
+}
+
+/* block/unlock the journal: */
+
+void bch2_journal_unblock(struct journal *j)
+{
+	spin_lock(&j->lock);
+	j->blocked--;
+	spin_unlock(&j->lock);
+
+	journal_wake(j);
+}
+
+void bch2_journal_block(struct journal *j)
+{
+	spin_lock(&j->lock);
+	j->blocked++;
+	spin_unlock(&j->lock);
+
+	journal_quiesce(j);
+}
+
+/* allocate journal on a device: */
+
+static int __bch2_set_nr_journal_buckets(struct bch_dev *ca, unsigned nr,
+					 bool new_fs, struct closure *cl)
+{
+	struct bch_fs *c = ca->fs;
+	struct journal_device *ja = &ca->journal;
+	u64 *new_bucket_seq = NULL, *new_buckets = NULL;
+	struct open_bucket **ob = NULL;
+	long *bu = NULL;
+	unsigned i, pos, nr_got = 0, nr_want = nr - ja->nr;
+	int ret = 0;
+
+	BUG_ON(nr <= ja->nr);
+
+	bu		= kcalloc(nr_want, sizeof(*bu), GFP_KERNEL);
+	ob		= kcalloc(nr_want, sizeof(*ob), GFP_KERNEL);
+	new_buckets	= kcalloc(nr, sizeof(u64), GFP_KERNEL);
+	new_bucket_seq	= kcalloc(nr, sizeof(u64), GFP_KERNEL);
+	if (!bu || !ob || !new_buckets || !new_bucket_seq) {
+		ret = -BCH_ERR_ENOMEM_set_nr_journal_buckets;
+		goto err_free;
+	}
+
+	for (nr_got = 0; nr_got < nr_want; nr_got++) {
+		if (new_fs) {
+			bu[nr_got] = bch2_bucket_alloc_new_fs(ca);
+			if (bu[nr_got] < 0) {
+				ret = -BCH_ERR_ENOSPC_bucket_alloc;
+				break;
+			}
+		} else {
+			ob[nr_got] = bch2_bucket_alloc(c, ca, BCH_WATERMARK_normal, cl);
+			ret = PTR_ERR_OR_ZERO(ob[nr_got]);
+			if (ret)
+				break;
+
+			ret = bch2_trans_run(c,
+				bch2_trans_mark_metadata_bucket(trans, ca,
+						ob[nr_got]->bucket, BCH_DATA_journal,
+						ca->mi.bucket_size));
+			if (ret) {
+				bch2_open_bucket_put(c, ob[nr_got]);
+				bch_err_msg(c, ret, "marking new journal buckets");
+				break;
+			}
+
+			bu[nr_got] = ob[nr_got]->bucket;
+		}
+	}
+
+	if (!nr_got)
+		goto err_free;
+
+	/* Don't return an error if we successfully allocated some buckets: */
+	ret = 0;
+
+	if (c) {
+		bch2_journal_flush_all_pins(&c->journal);
+		bch2_journal_block(&c->journal);
+		mutex_lock(&c->sb_lock);
+	}
+
+	memcpy(new_buckets,	ja->buckets,	ja->nr * sizeof(u64));
+	memcpy(new_bucket_seq,	ja->bucket_seq,	ja->nr * sizeof(u64));
+
+	BUG_ON(ja->discard_idx > ja->nr);
+
+	pos = ja->discard_idx ?: ja->nr;
+
+	memmove(new_buckets + pos + nr_got,
+		new_buckets + pos,
+		sizeof(new_buckets[0]) * (ja->nr - pos));
+	memmove(new_bucket_seq + pos + nr_got,
+		new_bucket_seq + pos,
+		sizeof(new_bucket_seq[0]) * (ja->nr - pos));
+
+	for (i = 0; i < nr_got; i++) {
+		new_buckets[pos + i] = bu[i];
+		new_bucket_seq[pos + i] = 0;
+	}
+
+	nr = ja->nr + nr_got;
+
+	ret = bch2_journal_buckets_to_sb(c, ca, new_buckets, nr);
+	if (ret)
+		goto err_unblock;
+
+	if (!new_fs)
+		bch2_write_super(c);
+
+	/* Commit: */
+	if (c)
+		spin_lock(&c->journal.lock);
+
+	swap(new_buckets,	ja->buckets);
+	swap(new_bucket_seq,	ja->bucket_seq);
+	ja->nr = nr;
+
+	if (pos <= ja->discard_idx)
+		ja->discard_idx = (ja->discard_idx + nr_got) % ja->nr;
+	if (pos <= ja->dirty_idx_ondisk)
+		ja->dirty_idx_ondisk = (ja->dirty_idx_ondisk + nr_got) % ja->nr;
+	if (pos <= ja->dirty_idx)
+		ja->dirty_idx = (ja->dirty_idx + nr_got) % ja->nr;
+	if (pos <= ja->cur_idx)
+		ja->cur_idx = (ja->cur_idx + nr_got) % ja->nr;
+
+	if (c)
+		spin_unlock(&c->journal.lock);
+err_unblock:
+	if (c) {
+		bch2_journal_unblock(&c->journal);
+		mutex_unlock(&c->sb_lock);
+	}
+
+	if (ret && !new_fs)
+		for (i = 0; i < nr_got; i++)
+			bch2_trans_run(c,
+				bch2_trans_mark_metadata_bucket(trans, ca,
+						bu[i], BCH_DATA_free, 0));
+err_free:
+	if (!new_fs)
+		for (i = 0; i < nr_got; i++)
+			bch2_open_bucket_put(c, ob[i]);
+
+	kfree(new_bucket_seq);
+	kfree(new_buckets);
+	kfree(ob);
+	kfree(bu);
+	return ret;
+}
+
+/*
+ * Allocate more journal space at runtime - not currently making use if it, but
+ * the code works:
+ */
+int bch2_set_nr_journal_buckets(struct bch_fs *c, struct bch_dev *ca,
+				unsigned nr)
+{
+	struct journal_device *ja = &ca->journal;
+	struct closure cl;
+	int ret = 0;
+
+	closure_init_stack(&cl);
+
+	down_write(&c->state_lock);
+
+	/* don't handle reducing nr of buckets yet: */
+	if (nr < ja->nr)
+		goto unlock;
+
+	while (ja->nr < nr) {
+		struct disk_reservation disk_res = { 0, 0, 0 };
+
+		/*
+		 * note: journal buckets aren't really counted as _sectors_ used yet, so
+		 * we don't need the disk reservation to avoid the BUG_ON() in buckets.c
+		 * when space used goes up without a reservation - but we do need the
+		 * reservation to ensure we'll actually be able to allocate:
+		 *
+		 * XXX: that's not right, disk reservations only ensure a
+		 * filesystem-wide allocation will succeed, this is a device
+		 * specific allocation - we can hang here:
+		 */
+
+		ret = bch2_disk_reservation_get(c, &disk_res,
+						bucket_to_sector(ca, nr - ja->nr), 1, 0);
+		if (ret)
+			break;
+
+		ret = __bch2_set_nr_journal_buckets(ca, nr, false, &cl);
+
+		bch2_disk_reservation_put(c, &disk_res);
+
+		closure_sync(&cl);
+
+		if (ret && ret != -BCH_ERR_bucket_alloc_blocked)
+			break;
+	}
+
+	if (ret)
+		bch_err_fn(c, ret);
+unlock:
+	up_write(&c->state_lock);
+	return ret;
+}
+
+int bch2_dev_journal_alloc(struct bch_dev *ca)
+{
+	unsigned nr;
+	int ret;
+
+	if (dynamic_fault("bcachefs:add:journal_alloc")) {
+		ret = -BCH_ERR_ENOMEM_set_nr_journal_buckets;
+		goto err;
+	}
+
+	/* 1/128th of the device by default: */
+	nr = ca->mi.nbuckets >> 7;
+
+	/*
+	 * clamp journal size to 8192 buckets or 8GB (in sectors), whichever
+	 * is smaller:
+	 */
+	nr = clamp_t(unsigned, nr,
+		     BCH_JOURNAL_BUCKETS_MIN,
+		     min(1 << 13,
+			 (1 << 24) / ca->mi.bucket_size));
+
+	ret = __bch2_set_nr_journal_buckets(ca, nr, true, NULL);
+err:
+	if (ret)
+		bch_err_fn(ca, ret);
+	return ret;
+}
+
+int bch2_fs_journal_alloc(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	unsigned i;
+
+	for_each_online_member(ca, c, i) {
+		if (ca->journal.nr)
+			continue;
+
+		int ret = bch2_dev_journal_alloc(ca);
+		if (ret) {
+			percpu_ref_put(&ca->io_ref);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/* startup/shutdown: */
+
+static bool bch2_journal_writing_to_device(struct journal *j, unsigned dev_idx)
+{
+	bool ret = false;
+	u64 seq;
+
+	spin_lock(&j->lock);
+	for (seq = journal_last_unwritten_seq(j);
+	     seq <= journal_cur_seq(j) && !ret;
+	     seq++) {
+		struct journal_buf *buf = journal_seq_to_buf(j, seq);
+
+		if (bch2_bkey_has_device_c(bkey_i_to_s_c(&buf->key), dev_idx))
+			ret = true;
+	}
+	spin_unlock(&j->lock);
+
+	return ret;
+}
+
+void bch2_dev_journal_stop(struct journal *j, struct bch_dev *ca)
+{
+	wait_event(j->wait, !bch2_journal_writing_to_device(j, ca->dev_idx));
+}
+
+void bch2_fs_journal_stop(struct journal *j)
+{
+	bch2_journal_reclaim_stop(j);
+	bch2_journal_flush_all_pins(j);
+
+	wait_event(j->wait, bch2_journal_entry_close(j));
+
+	/*
+	 * Always write a new journal entry, to make sure the clock hands are up
+	 * to date (and match the superblock)
+	 */
+	bch2_journal_meta(j);
+
+	journal_quiesce(j);
+
+	BUG_ON(!bch2_journal_error(j) &&
+	       test_bit(JOURNAL_REPLAY_DONE, &j->flags) &&
+	       j->last_empty_seq != journal_cur_seq(j));
+
+	cancel_delayed_work_sync(&j->write_work);
+}
+
+int bch2_fs_journal_start(struct journal *j, u64 cur_seq)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	struct journal_entry_pin_list *p;
+	struct journal_replay *i, **_i;
+	struct genradix_iter iter;
+	bool had_entries = false;
+	unsigned ptr;
+	u64 last_seq = cur_seq, nr, seq;
+
+	genradix_for_each_reverse(&c->journal_entries, iter, _i) {
+		i = *_i;
+
+		if (!i || i->ignore)
+			continue;
+
+		last_seq = le64_to_cpu(i->j.last_seq);
+		break;
+	}
+
+	nr = cur_seq - last_seq;
+
+	if (nr + 1 > j->pin.size) {
+		free_fifo(&j->pin);
+		init_fifo(&j->pin, roundup_pow_of_two(nr + 1), GFP_KERNEL);
+		if (!j->pin.data) {
+			bch_err(c, "error reallocating journal fifo (%llu open entries)", nr);
+			return -BCH_ERR_ENOMEM_journal_pin_fifo;
+		}
+	}
+
+	j->replay_journal_seq	= last_seq;
+	j->replay_journal_seq_end = cur_seq;
+	j->last_seq_ondisk	= last_seq;
+	j->flushed_seq_ondisk	= cur_seq - 1;
+	j->seq_ondisk		= cur_seq - 1;
+	j->pin.front		= last_seq;
+	j->pin.back		= cur_seq;
+	atomic64_set(&j->seq, cur_seq - 1);
+
+	fifo_for_each_entry_ptr(p, &j->pin, seq)
+		journal_pin_list_init(p, 1);
+
+	genradix_for_each(&c->journal_entries, iter, _i) {
+		i = *_i;
+
+		if (!i || i->ignore)
+			continue;
+
+		seq = le64_to_cpu(i->j.seq);
+		BUG_ON(seq >= cur_seq);
+
+		if (seq < last_seq)
+			continue;
+
+		if (journal_entry_empty(&i->j))
+			j->last_empty_seq = le64_to_cpu(i->j.seq);
+
+		p = journal_seq_pin(j, seq);
+
+		p->devs.nr = 0;
+		for (ptr = 0; ptr < i->nr_ptrs; ptr++)
+			bch2_dev_list_add_dev(&p->devs, i->ptrs[ptr].dev);
+
+		had_entries = true;
+	}
+
+	if (!had_entries)
+		j->last_empty_seq = cur_seq;
+
+	spin_lock(&j->lock);
+
+	set_bit(JOURNAL_STARTED, &j->flags);
+	j->last_flush_write = jiffies;
+
+	j->reservations.idx = j->reservations.unwritten_idx = journal_cur_seq(j);
+	j->reservations.unwritten_idx++;
+
+	c->last_bucket_seq_cleanup = journal_cur_seq(j);
+
+	bch2_journal_space_available(j);
+	spin_unlock(&j->lock);
+
+	return bch2_journal_reclaim_start(j);
+}
+
+/* init/exit: */
+
+void bch2_dev_journal_exit(struct bch_dev *ca)
+{
+	kfree(ca->journal.bio);
+	kfree(ca->journal.buckets);
+	kfree(ca->journal.bucket_seq);
+
+	ca->journal.bio		= NULL;
+	ca->journal.buckets	= NULL;
+	ca->journal.bucket_seq	= NULL;
+}
+
+int bch2_dev_journal_init(struct bch_dev *ca, struct bch_sb *sb)
+{
+	struct journal_device *ja = &ca->journal;
+	struct bch_sb_field_journal *journal_buckets =
+		bch2_sb_field_get(sb, journal);
+	struct bch_sb_field_journal_v2 *journal_buckets_v2 =
+		bch2_sb_field_get(sb, journal_v2);
+	unsigned i, nr_bvecs;
+
+	ja->nr = 0;
+
+	if (journal_buckets_v2) {
+		unsigned nr = bch2_sb_field_journal_v2_nr_entries(journal_buckets_v2);
+
+		for (i = 0; i < nr; i++)
+			ja->nr += le64_to_cpu(journal_buckets_v2->d[i].nr);
+	} else if (journal_buckets) {
+		ja->nr = bch2_nr_journal_buckets(journal_buckets);
+	}
+
+	ja->bucket_seq = kcalloc(ja->nr, sizeof(u64), GFP_KERNEL);
+	if (!ja->bucket_seq)
+		return -BCH_ERR_ENOMEM_dev_journal_init;
+
+	nr_bvecs = DIV_ROUND_UP(JOURNAL_ENTRY_SIZE_MAX, PAGE_SIZE);
+
+	ca->journal.bio = bio_kmalloc(nr_bvecs, GFP_KERNEL);
+	if (!ca->journal.bio)
+		return -BCH_ERR_ENOMEM_dev_journal_init;
+
+	bio_init(ca->journal.bio, NULL, ca->journal.bio->bi_inline_vecs, nr_bvecs, 0);
+
+	ja->buckets = kcalloc(ja->nr, sizeof(u64), GFP_KERNEL);
+	if (!ja->buckets)
+		return -BCH_ERR_ENOMEM_dev_journal_init;
+
+	if (journal_buckets_v2) {
+		unsigned nr = bch2_sb_field_journal_v2_nr_entries(journal_buckets_v2);
+		unsigned j, dst = 0;
+
+		for (i = 0; i < nr; i++)
+			for (j = 0; j < le64_to_cpu(journal_buckets_v2->d[i].nr); j++)
+				ja->buckets[dst++] =
+					le64_to_cpu(journal_buckets_v2->d[i].start) + j;
+	} else if (journal_buckets) {
+		for (i = 0; i < ja->nr; i++)
+			ja->buckets[i] = le64_to_cpu(journal_buckets->buckets[i]);
+	}
+
+	return 0;
+}
+
+void bch2_fs_journal_exit(struct journal *j)
+{
+	unsigned i;
+
+	darray_exit(&j->early_journal_entries);
+
+	for (i = 0; i < ARRAY_SIZE(j->buf); i++)
+		kvpfree(j->buf[i].data, j->buf[i].buf_size);
+	free_fifo(&j->pin);
+}
+
+int bch2_fs_journal_init(struct journal *j)
+{
+	static struct lock_class_key res_key;
+	unsigned i;
+
+	spin_lock_init(&j->lock);
+	spin_lock_init(&j->err_lock);
+	init_waitqueue_head(&j->wait);
+	INIT_DELAYED_WORK(&j->write_work, journal_write_work);
+	init_waitqueue_head(&j->reclaim_wait);
+	init_waitqueue_head(&j->pin_flush_wait);
+	mutex_init(&j->reclaim_lock);
+	mutex_init(&j->discard_lock);
+
+	lockdep_init_map(&j->res_map, "journal res", &res_key, 0);
+
+	atomic64_set(&j->reservations.counter,
+		((union journal_res_state)
+		 { .cur_entry_offset = JOURNAL_ENTRY_CLOSED_VAL }).v);
+
+	if (!(init_fifo(&j->pin, JOURNAL_PIN, GFP_KERNEL)))
+		return -BCH_ERR_ENOMEM_journal_pin_fifo;
+
+	for (i = 0; i < ARRAY_SIZE(j->buf); i++) {
+		j->buf[i].buf_size = JOURNAL_ENTRY_SIZE_MIN;
+		j->buf[i].data = kvpmalloc(j->buf[i].buf_size, GFP_KERNEL);
+		if (!j->buf[i].data)
+			return -BCH_ERR_ENOMEM_journal_buf;
+	}
+
+	j->pin.front = j->pin.back = 1;
+	return 0;
+}
+
+/* debug: */
+
+void __bch2_journal_debug_to_text(struct printbuf *out, struct journal *j)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	union journal_res_state s;
+	struct bch_dev *ca;
+	unsigned long now = jiffies;
+	u64 seq;
+	unsigned i;
+
+	if (!out->nr_tabstops)
+		printbuf_tabstop_push(out, 24);
+	out->atomic++;
+
+	rcu_read_lock();
+	s = READ_ONCE(j->reservations);
+
+	prt_printf(out, "dirty journal entries:\t%llu/%llu\n",	fifo_used(&j->pin), j->pin.size);
+	prt_printf(out, "seq:\t\t\t%llu\n",			journal_cur_seq(j));
+	prt_printf(out, "seq_ondisk:\t\t%llu\n",		j->seq_ondisk);
+	prt_printf(out, "last_seq:\t\t%llu\n",		journal_last_seq(j));
+	prt_printf(out, "last_seq_ondisk:\t%llu\n",		j->last_seq_ondisk);
+	prt_printf(out, "flushed_seq_ondisk:\t%llu\n",	j->flushed_seq_ondisk);
+	prt_printf(out, "watermark:\t\t%s\n",		bch2_watermarks[j->watermark]);
+	prt_printf(out, "each entry reserved:\t%u\n",	j->entry_u64s_reserved);
+	prt_printf(out, "nr flush writes:\t%llu\n",		j->nr_flush_writes);
+	prt_printf(out, "nr noflush writes:\t%llu\n",	j->nr_noflush_writes);
+	prt_printf(out, "nr direct reclaim:\t%llu\n",	j->nr_direct_reclaim);
+	prt_printf(out, "nr background reclaim:\t%llu\n",	j->nr_background_reclaim);
+	prt_printf(out, "reclaim kicked:\t\t%u\n",		j->reclaim_kicked);
+	prt_printf(out, "reclaim runs in:\t%u ms\n",	time_after(j->next_reclaim, now)
+	       ? jiffies_to_msecs(j->next_reclaim - jiffies) : 0);
+	prt_printf(out, "current entry sectors:\t%u\n",	j->cur_entry_sectors);
+	prt_printf(out, "current entry error:\t%s\n",	bch2_journal_errors[j->cur_entry_error]);
+	prt_printf(out, "current entry:\t\t");
+
+	switch (s.cur_entry_offset) {
+	case JOURNAL_ENTRY_ERROR_VAL:
+		prt_printf(out, "error");
+		break;
+	case JOURNAL_ENTRY_CLOSED_VAL:
+		prt_printf(out, "closed");
+		break;
+	default:
+		prt_printf(out, "%u/%u", s.cur_entry_offset, j->cur_entry_u64s);
+		break;
+	}
+
+	prt_newline(out);
+
+	for (seq = journal_cur_seq(j);
+	     seq >= journal_last_unwritten_seq(j);
+	     --seq) {
+		i = seq & JOURNAL_BUF_MASK;
+
+		prt_printf(out, "unwritten entry:");
+		prt_tab(out);
+		prt_printf(out, "%llu", seq);
+		prt_newline(out);
+		printbuf_indent_add(out, 2);
+
+		prt_printf(out, "refcount:");
+		prt_tab(out);
+		prt_printf(out, "%u", journal_state_count(s, i));
+		prt_newline(out);
+
+		prt_printf(out, "sectors:");
+		prt_tab(out);
+		prt_printf(out, "%u", j->buf[i].sectors);
+		prt_newline(out);
+
+		prt_printf(out, "expires");
+		prt_tab(out);
+		prt_printf(out, "%li jiffies", j->buf[i].expires - jiffies);
+		prt_newline(out);
+
+		printbuf_indent_sub(out, 2);
+	}
+
+	prt_printf(out,
+	       "replay done:\t\t%i\n",
+	       test_bit(JOURNAL_REPLAY_DONE,	&j->flags));
+
+	prt_printf(out, "space:\n");
+	prt_printf(out, "\tdiscarded\t%u:%u\n",
+	       j->space[journal_space_discarded].next_entry,
+	       j->space[journal_space_discarded].total);
+	prt_printf(out, "\tclean ondisk\t%u:%u\n",
+	       j->space[journal_space_clean_ondisk].next_entry,
+	       j->space[journal_space_clean_ondisk].total);
+	prt_printf(out, "\tclean\t\t%u:%u\n",
+	       j->space[journal_space_clean].next_entry,
+	       j->space[journal_space_clean].total);
+	prt_printf(out, "\ttotal\t\t%u:%u\n",
+	       j->space[journal_space_total].next_entry,
+	       j->space[journal_space_total].total);
+
+	for_each_member_device_rcu(ca, c, i,
+				   &c->rw_devs[BCH_DATA_journal]) {
+		struct journal_device *ja = &ca->journal;
+
+		if (!test_bit(ca->dev_idx, c->rw_devs[BCH_DATA_journal].d))
+			continue;
+
+		if (!ja->nr)
+			continue;
+
+		prt_printf(out, "dev %u:\n",		i);
+		prt_printf(out, "\tnr\t\t%u\n",		ja->nr);
+		prt_printf(out, "\tbucket size\t%u\n",	ca->mi.bucket_size);
+		prt_printf(out, "\tavailable\t%u:%u\n",	bch2_journal_dev_buckets_available(j, ja, journal_space_discarded), ja->sectors_free);
+		prt_printf(out, "\tdiscard_idx\t%u\n",	ja->discard_idx);
+		prt_printf(out, "\tdirty_ondisk\t%u (seq %llu)\n", ja->dirty_idx_ondisk,	ja->bucket_seq[ja->dirty_idx_ondisk]);
+		prt_printf(out, "\tdirty_idx\t%u (seq %llu)\n", ja->dirty_idx,		ja->bucket_seq[ja->dirty_idx]);
+		prt_printf(out, "\tcur_idx\t\t%u (seq %llu)\n", ja->cur_idx,		ja->bucket_seq[ja->cur_idx]);
+	}
+
+	rcu_read_unlock();
+
+	--out->atomic;
+}
+
+void bch2_journal_debug_to_text(struct printbuf *out, struct journal *j)
+{
+	spin_lock(&j->lock);
+	__bch2_journal_debug_to_text(out, j);
+	spin_unlock(&j->lock);
+}
+
+bool bch2_journal_seq_pins_to_text(struct printbuf *out, struct journal *j, u64 *seq)
+{
+	struct journal_entry_pin_list *pin_list;
+	struct journal_entry_pin *pin;
+	unsigned i;
+
+	spin_lock(&j->lock);
+	*seq = max(*seq, j->pin.front);
+
+	if (*seq >= j->pin.back) {
+		spin_unlock(&j->lock);
+		return true;
+	}
+
+	out->atomic++;
+
+	pin_list = journal_seq_pin(j, *seq);
+
+	prt_printf(out, "%llu: count %u", *seq, atomic_read(&pin_list->count));
+	prt_newline(out);
+	printbuf_indent_add(out, 2);
+
+	for (i = 0; i < ARRAY_SIZE(pin_list->list); i++)
+		list_for_each_entry(pin, &pin_list->list[i], list) {
+			prt_printf(out, "\t%px %ps", pin, pin->flush);
+			prt_newline(out);
+		}
+
+	if (!list_empty(&pin_list->flushed)) {
+		prt_printf(out, "flushed:");
+		prt_newline(out);
+	}
+
+	list_for_each_entry(pin, &pin_list->flushed, list) {
+		prt_printf(out, "\t%px %ps", pin, pin->flush);
+		prt_newline(out);
+	}
+
+	printbuf_indent_sub(out, 2);
+
+	--out->atomic;
+	spin_unlock(&j->lock);
+
+	return false;
+}
+
+void bch2_journal_pins_to_text(struct printbuf *out, struct journal *j)
+{
+	u64 seq = 0;
+
+	while (!bch2_journal_seq_pins_to_text(out, j, &seq))
+		seq++;
+}