From 1e690efa72596a1163dc56709707f459221889d2 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Mon, 10 Feb 2025 11:34:59 -0500 Subject: [PATCH] bcachefs: Split out journal pins by btree level This lets us flush the journal to go read-only more effectively. Flushing the journal and going read-only requires halting mutually recursive processes, which strictly speaking are not guaranteed to terminate. Flushing btree node journal pins will kick off a btree node write, and btree node writes on completion must do another btree update to the parent node to update the 'sectors_written' field for that node's key. If the parent node is full and requires a split or compaction, that's going to generate a whole bunch of additional btree updates - alloc info, LRU btree, and more - which then have to be flushed, and the cycle repeats. This process will terminate much more effectively if we tweak journal reclaim to flush btree updates leaf to root: i.e., don't flush updates for a given btree node (kicking off a write, and consuming space within that node up to the next block boundary) if there might still be unflushed updates in child nodes. Signed-off-by: Kent Overstreet --- fs/bcachefs/journal_reclaim.c | 37 +++++++++++++++++------------------ fs/bcachefs/journal_types.h | 5 ++++- 2 files changed, 22 insertions(+), 20 deletions(-) diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c index 6a9cefb635d6..d373cd181a7f 100644 --- a/fs/bcachefs/journal_reclaim.c +++ b/fs/bcachefs/journal_reclaim.c @@ -384,12 +384,16 @@ void bch2_journal_pin_drop(struct journal *j, spin_unlock(&j->lock); } -static enum journal_pin_type journal_pin_type(journal_pin_flush_fn fn) +static enum journal_pin_type journal_pin_type(struct journal_entry_pin *pin, + journal_pin_flush_fn fn) { if (fn == bch2_btree_node_flush0 || - fn == bch2_btree_node_flush1) - return JOURNAL_PIN_TYPE_btree; - else if (fn == bch2_btree_key_cache_journal_flush) + fn == bch2_btree_node_flush1) { + unsigned idx = fn == bch2_btree_node_flush1; + struct btree *b = container_of(pin, struct btree, writes[idx].journal); + + return JOURNAL_PIN_TYPE_btree0 - b->c.level; + } else if (fn == bch2_btree_key_cache_journal_flush) return JOURNAL_PIN_TYPE_key_cache; else return JOURNAL_PIN_TYPE_other; @@ -441,7 +445,7 @@ void bch2_journal_pin_copy(struct journal *j, bool reclaim = __journal_pin_drop(j, dst); - bch2_journal_pin_set_locked(j, seq, dst, flush_fn, journal_pin_type(flush_fn)); + bch2_journal_pin_set_locked(j, seq, dst, flush_fn, journal_pin_type(dst, flush_fn)); if (reclaim) bch2_journal_reclaim_fast(j); @@ -465,7 +469,7 @@ void bch2_journal_pin_set(struct journal *j, u64 seq, bool reclaim = __journal_pin_drop(j, pin); - bch2_journal_pin_set_locked(j, seq, pin, flush_fn, journal_pin_type(flush_fn)); + bch2_journal_pin_set_locked(j, seq, pin, flush_fn, journal_pin_type(pin, flush_fn)); if (reclaim) bch2_journal_reclaim_fast(j); @@ -587,7 +591,7 @@ static size_t journal_flush_pins(struct journal *j, spin_lock(&j->lock); /* Pin might have been dropped or rearmed: */ if (likely(!err && !j->flush_in_progress_dropped)) - list_move(&pin->list, &journal_seq_pin(j, seq)->flushed[journal_pin_type(flush_fn)]); + list_move(&pin->list, &journal_seq_pin(j, seq)->flushed[journal_pin_type(pin, flush_fn)]); j->flush_in_progress = NULL; j->flush_in_progress_dropped = false; spin_unlock(&j->lock); @@ -869,18 +873,13 @@ static int journal_flush_done(struct journal *j, u64 seq_to_flush, mutex_lock(&j->reclaim_lock); - if (journal_flush_pins_or_still_flushing(j, seq_to_flush, - BIT(JOURNAL_PIN_TYPE_key_cache)| - BIT(JOURNAL_PIN_TYPE_other))) { - *did_work = true; - goto unlock; - } - - if (journal_flush_pins_or_still_flushing(j, seq_to_flush, - BIT(JOURNAL_PIN_TYPE_btree))) { - *did_work = true; - goto unlock; - } + for (int type = JOURNAL_PIN_TYPE_NR - 1; + type >= 0; + --type) + if (journal_flush_pins_or_still_flushing(j, seq_to_flush, BIT(type))) { + *did_work = true; + goto unlock; + } if (seq_to_flush > journal_cur_seq(j)) bch2_journal_entry_close(j); diff --git a/fs/bcachefs/journal_types.h b/fs/bcachefs/journal_types.h index a198a81d7478..1ef3a28ed6ab 100644 --- a/fs/bcachefs/journal_types.h +++ b/fs/bcachefs/journal_types.h @@ -53,7 +53,10 @@ struct journal_buf { */ enum journal_pin_type { - JOURNAL_PIN_TYPE_btree, + JOURNAL_PIN_TYPE_btree3, + JOURNAL_PIN_TYPE_btree2, + JOURNAL_PIN_TYPE_btree1, + JOURNAL_PIN_TYPE_btree0, JOURNAL_PIN_TYPE_key_cache, JOURNAL_PIN_TYPE_other, JOURNAL_PIN_TYPE_NR,