1 files changed, 402 insertions, 0 deletions

diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c
new file mode 100644
index 000000000000..e5b8666fa052
--- /dev/null
+++ b/fs/bcachefs/journal_reclaim.c
@@ -0,0 +1,402 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "journal.h"
+#include "journal_reclaim.h"
+#include "replicas.h"
+#include "super.h"
+
+/*
+ * Journal entry pinning - machinery for holding a reference on a given journal
+ * entry, holding it open to ensure it gets replayed during recovery:
+ */
+
+static inline u64 journal_pin_seq(struct journal *j,
+				  struct journal_entry_pin_list *pin_list)
+{
+	return fifo_entry_idx_abs(&j->pin, pin_list);
+}
+
+u64 bch2_journal_pin_seq(struct journal *j, struct journal_entry_pin *pin)
+{
+	u64 ret = 0;
+
+	spin_lock(&j->lock);
+	if (journal_pin_active(pin))
+		ret = journal_pin_seq(j, pin->pin_list);
+	spin_unlock(&j->lock);
+
+	return ret;
+}
+
+static inline void __journal_pin_add(struct journal *j,
+				     struct journal_entry_pin_list *pin_list,
+				     struct journal_entry_pin *pin,
+				     journal_pin_flush_fn flush_fn)
+{
+	BUG_ON(journal_pin_active(pin));
+	BUG_ON(!atomic_read(&pin_list->count));
+
+	atomic_inc(&pin_list->count);
+	pin->pin_list	= pin_list;
+	pin->flush	= flush_fn;
+
+	if (flush_fn)
+		list_add(&pin->list, &pin_list->list);
+	else
+		INIT_LIST_HEAD(&pin->list);
+
+	/*
+	 * If the journal is currently full,  we might want to call flush_fn
+	 * immediately:
+	 */
+	journal_wake(j);
+}
+
+void bch2_journal_pin_add(struct journal *j, u64 seq,
+			  struct journal_entry_pin *pin,
+			  journal_pin_flush_fn flush_fn)
+{
+	spin_lock(&j->lock);
+	__journal_pin_add(j, journal_seq_pin(j, seq), pin, flush_fn);
+	spin_unlock(&j->lock);
+}
+
+static inline void __journal_pin_drop(struct journal *j,
+				      struct journal_entry_pin *pin)
+{
+	struct journal_entry_pin_list *pin_list = pin->pin_list;
+
+	if (!journal_pin_active(pin))
+		return;
+
+	pin->pin_list = NULL;
+	list_del_init(&pin->list);
+
+	/*
+	 * Unpinning a journal entry make make journal_next_bucket() succeed, if
+	 * writing a new last_seq will now make another bucket available:
+	 */
+	if (atomic_dec_and_test(&pin_list->count) &&
+	    pin_list == &fifo_peek_front(&j->pin))
+		bch2_journal_reclaim_fast(j);
+}
+
+void bch2_journal_pin_drop(struct journal *j,
+			  struct journal_entry_pin *pin)
+{
+	spin_lock(&j->lock);
+	__journal_pin_drop(j, pin);
+	spin_unlock(&j->lock);
+}
+
+void bch2_journal_pin_add_if_older(struct journal *j,
+				  struct journal_entry_pin *src_pin,
+				  struct journal_entry_pin *pin,
+				  journal_pin_flush_fn flush_fn)
+{
+	spin_lock(&j->lock);
+
+	if (journal_pin_active(src_pin) &&
+	    (!journal_pin_active(pin) ||
+	     journal_pin_seq(j, src_pin->pin_list) <
+	     journal_pin_seq(j, pin->pin_list))) {
+		__journal_pin_drop(j, pin);
+		__journal_pin_add(j, src_pin->pin_list, pin, flush_fn);
+	}
+
+	spin_unlock(&j->lock);
+}
+
+/*
+ * Journal reclaim: flush references to open journal entries to reclaim space in
+ * the journal
+ *
+ * May be done by the journal code in the background as needed to free up space
+ * for more journal entries, or as part of doing a clean shutdown, or to migrate
+ * data off of a specific device:
+ */
+
+/**
+ * bch2_journal_reclaim_fast - do the fast part of journal reclaim
+ *
+ * Called from IO submission context, does not block. Cleans up after btree
+ * write completions by advancing the journal pin and each cache's last_idx,
+ * kicking off discards and background reclaim as necessary.
+ */
+void bch2_journal_reclaim_fast(struct journal *j)
+{
+	struct journal_entry_pin_list temp;
+	bool popped = false;
+
+	lockdep_assert_held(&j->lock);
+
+	/*
+	 * Unpin journal entries whose reference counts reached zero, meaning
+	 * all btree nodes got written out
+	 */
+	while (!atomic_read(&fifo_peek_front(&j->pin).count)) {
+		BUG_ON(!list_empty(&fifo_peek_front(&j->pin).list));
+		BUG_ON(!fifo_pop(&j->pin, temp));
+		popped = true;
+	}
+
+	if (popped)
+		journal_wake(j);
+}
+
+static struct journal_entry_pin *
+__journal_get_next_pin(struct journal *j, u64 seq_to_flush, u64 *seq)
+{
+	struct journal_entry_pin_list *pin_list;
+	struct journal_entry_pin *ret;
+	u64 iter;
+
+	/* no need to iterate over empty fifo entries: */
+	bch2_journal_reclaim_fast(j);
+
+	fifo_for_each_entry_ptr(pin_list, &j->pin, iter) {
+		if (iter > seq_to_flush)
+			break;
+
+		ret = list_first_entry_or_null(&pin_list->list,
+				struct journal_entry_pin, list);
+		if (ret) {
+			/* must be list_del_init(), see bch2_journal_pin_drop() */
+			list_move(&ret->list, &pin_list->flushed);
+			*seq = iter;
+			return ret;
+		}
+	}
+
+	return NULL;
+}
+
+static struct journal_entry_pin *
+journal_get_next_pin(struct journal *j, u64 seq_to_flush, u64 *seq)
+{
+	struct journal_entry_pin *ret;
+
+	spin_lock(&j->lock);
+	ret = __journal_get_next_pin(j, seq_to_flush, seq);
+	spin_unlock(&j->lock);
+
+	return ret;
+}
+
+static bool should_discard_bucket(struct journal *j, struct journal_device *ja)
+{
+	bool ret;
+
+	spin_lock(&j->lock);
+	ret = ja->nr &&
+		(ja->last_idx != ja->cur_idx &&
+		 ja->bucket_seq[ja->last_idx] < j->last_seq_ondisk);
+	spin_unlock(&j->lock);
+
+	return ret;
+}
+
+/**
+ * bch2_journal_reclaim_work - free up journal buckets
+ *
+ * Background journal reclaim writes out btree nodes. It should be run
+ * early enough so that we never completely run out of journal buckets.
+ *
+ * High watermarks for triggering background reclaim:
+ * - FIFO has fewer than 512 entries left
+ * - fewer than 25% journal buckets free
+ *
+ * Background reclaim runs until low watermarks are reached:
+ * - FIFO has more than 1024 entries left
+ * - more than 50% journal buckets free
+ *
+ * As long as a reclaim can complete in the time it takes to fill up
+ * 512 journal entries or 25% of all journal buckets, then
+ * journal_next_bucket() should not stall.
+ */
+void bch2_journal_reclaim_work(struct work_struct *work)
+{
+	struct bch_fs *c = container_of(to_delayed_work(work),
+				struct bch_fs, journal.reclaim_work);
+	struct journal *j = &c->journal;
+	struct bch_dev *ca;
+	struct journal_entry_pin *pin;
+	u64 seq, seq_to_flush = 0;
+	unsigned iter, bucket_to_flush;
+	unsigned long next_flush;
+	bool reclaim_lock_held = false, need_flush;
+
+	/*
+	 * Advance last_idx to point to the oldest journal entry containing
+	 * btree node updates that have not yet been written out
+	 */
+	for_each_rw_member(ca, c, iter) {
+		struct journal_device *ja = &ca->journal;
+
+		if (!ja->nr)
+			continue;
+
+		while (should_discard_bucket(j, ja)) {
+			if (!reclaim_lock_held) {
+				/*
+				 * ugh:
+				 * might be called from __journal_res_get()
+				 * under wait_event() - have to go back to
+				 * TASK_RUNNING before doing something that
+				 * would block, but only if we're doing work:
+				 */
+				__set_current_state(TASK_RUNNING);
+
+				mutex_lock(&j->reclaim_lock);
+				reclaim_lock_held = true;
+				/* recheck under reclaim_lock: */
+				continue;
+			}
+
+			if (ca->mi.discard &&
+			    bdev_max_discard_sectors(ca->disk_sb.bdev))
+				blkdev_issue_discard(ca->disk_sb.bdev,
+					bucket_to_sector(ca,
+						ja->buckets[ja->last_idx]),
+					ca->mi.bucket_size, GFP_NOIO);
+
+			spin_lock(&j->lock);
+			ja->last_idx = (ja->last_idx + 1) % ja->nr;
+			spin_unlock(&j->lock);
+
+			journal_wake(j);
+		}
+
+		/*
+		 * Write out enough btree nodes to free up 50% journal
+		 * buckets
+		 */
+		spin_lock(&j->lock);
+		bucket_to_flush = (ja->cur_idx + (ja->nr >> 1)) % ja->nr;
+		seq_to_flush = max_t(u64, seq_to_flush,
+				     ja->bucket_seq[bucket_to_flush]);
+		spin_unlock(&j->lock);
+	}
+
+	if (reclaim_lock_held)
+		mutex_unlock(&j->reclaim_lock);
+
+	/* Also flush if the pin fifo is more than half full */
+	spin_lock(&j->lock);
+	seq_to_flush = max_t(s64, seq_to_flush,
+			     (s64) journal_cur_seq(j) -
+			     (j->pin.size >> 1));
+	spin_unlock(&j->lock);
+
+	/*
+	 * If it's been longer than j->reclaim_delay_ms since we last flushed,
+	 * make sure to flush at least one journal pin:
+	 */
+	next_flush = j->last_flushed + msecs_to_jiffies(j->reclaim_delay_ms);
+	need_flush = time_after(jiffies, next_flush);
+
+	while ((pin = journal_get_next_pin(j, need_flush
+					   ? U64_MAX
+					   : seq_to_flush, &seq))) {
+		__set_current_state(TASK_RUNNING);
+		pin->flush(j, pin, seq);
+		need_flush = false;
+
+		j->last_flushed = jiffies;
+	}
+
+	if (!test_bit(BCH_FS_RO, &c->flags))
+		queue_delayed_work(system_freezable_wq, &j->reclaim_work,
+				   msecs_to_jiffies(j->reclaim_delay_ms));
+}
+
+static int journal_flush_done(struct journal *j, u64 seq_to_flush,
+			      struct journal_entry_pin **pin,
+			      u64 *pin_seq)
+{
+	int ret;
+
+	*pin = NULL;
+
+	ret = bch2_journal_error(j);
+	if (ret)
+		return ret;
+
+	spin_lock(&j->lock);
+	/*
+	 * If journal replay hasn't completed, the unreplayed journal entries
+	 * hold refs on their corresponding sequence numbers
+	 */
+	ret = (*pin = __journal_get_next_pin(j, seq_to_flush, pin_seq)) != NULL ||
+		!test_bit(JOURNAL_REPLAY_DONE, &j->flags) ||
+		journal_last_seq(j) > seq_to_flush ||
+		(fifo_used(&j->pin) == 1 &&
+		 atomic_read(&fifo_peek_front(&j->pin).count) == 1);
+	spin_unlock(&j->lock);
+
+	return ret;
+}
+
+void bch2_journal_flush_pins(struct journal *j, u64 seq_to_flush)
+{
+	struct journal_entry_pin *pin;
+	u64 pin_seq;
+
+	if (!test_bit(JOURNAL_STARTED, &j->flags))
+		return;
+
+	while (1) {
+		wait_event(j->wait, journal_flush_done(j, seq_to_flush,
+						       &pin, &pin_seq));
+		if (!pin)
+			break;
+
+		pin->flush(j, pin, pin_seq);
+	}
+}
+
+int bch2_journal_flush_device_pins(struct journal *j, int dev_idx)
+{
+	struct bch_fs *c = container_of(j, struct bch_fs, journal);
+	struct journal_entry_pin_list *p;
+	struct bch_devs_list devs;
+	u64 iter, seq = 0;
+	int ret = 0;
+
+	spin_lock(&j->lock);
+	fifo_for_each_entry_ptr(p, &j->pin, iter)
+		if (dev_idx >= 0
+		    ? bch2_dev_list_has_dev(p->devs, dev_idx)
+		    : p->devs.nr < c->opts.metadata_replicas)
+			seq = iter;
+	spin_unlock(&j->lock);
+
+	bch2_journal_flush_pins(j, seq);
+
+	ret = bch2_journal_error(j);
+	if (ret)
+		return ret;
+
+	mutex_lock(&c->replicas_gc_lock);
+	bch2_replicas_gc_start(c, 1 << BCH_DATA_JOURNAL);
+
+	seq = 0;
+
+	spin_lock(&j->lock);
+	while (!ret && seq < j->pin.back) {
+		seq = max(seq, journal_last_seq(j));
+		devs = journal_seq_pin(j, seq)->devs;
+		seq++;
+
+		spin_unlock(&j->lock);
+		ret = bch2_mark_replicas(c, BCH_DATA_JOURNAL, devs);
+		spin_lock(&j->lock);
+	}
+	spin_unlock(&j->lock);
+
+	ret = bch2_replicas_gc_end(c, ret);
+	mutex_unlock(&c->replicas_gc_lock);
+
+	return ret;
+}