bcachefs: Disk space accounting rewrite

Main part of the disk accounting rewrite.

This is a wholesale rewrite of the existing disk space accounting, which
relies on percepu counters that are sharded by journal buffer, and
rolled up and added to each journal write.

With the new scheme, every set of counters is a distinct key in the
accounting btree; this fixes scaling limitations of the old scheme,
where counters took up space in each journal entry and required multiple
percpu counters.

Now, in memory accounting requires a single set of percpu counters - not
multiple for each in flight journal buffer - and in the future we'll
probably also have counters that don't use in memory percpu counters,
they're not strictly required.

An accounting update is now a normal btree update, using the btree write
buffer path. At transaction commit time, we apply accounting updates to
the in memory counters, which are percpu counters indexed in an
eytzinger tree by the accounting key.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 22 insertions, 5 deletions

diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
index a766eaf48863..dd7d14363a68 100644
--- a/fs/bcachefs/alloc_background.h
+++ b/fs/bcachefs/alloc_background.h
@@ -82,25 +82,39 @@ static inline bool bucket_data_type_mismatch(enum bch_data_type bucket,
 		bucket_data_type(bucket) != bucket_data_type(ptr);
 }
 
-static inline unsigned bch2_bucket_sectors_total(struct bch_alloc_v4 a)
+static inline s64 bch2_bucket_sectors_total(struct bch_alloc_v4 a)
 {
 	return a.stripe_sectors + a.dirty_sectors + a.cached_sectors;
 }
 
-static inline unsigned bch2_bucket_sectors_dirty(struct bch_alloc_v4 a)
+static inline s64 bch2_bucket_sectors_dirty(struct bch_alloc_v4 a)
 {
 	return a.stripe_sectors + a.dirty_sectors;
 }
 
-static inline unsigned bch2_bucket_sectors_fragmented(struct bch_dev *ca,
+static inline s64 bch2_bucket_sectors(struct bch_alloc_v4 a)
+{
+	return a.data_type == BCH_DATA_cached
+		? a.cached_sectors
+		: bch2_bucket_sectors_dirty(a);
+}
+
+static inline s64 bch2_bucket_sectors_fragmented(struct bch_dev *ca,
 						 struct bch_alloc_v4 a)
 {
-	int d = bch2_bucket_sectors_dirty(a);
+	int d = bch2_bucket_sectors(a);
+
+	return d ? max(0, ca->mi.bucket_size - d) : 0;
+}
+
+static inline s64 bch2_gc_bucket_sectors_fragmented(struct bch_dev *ca, struct bucket a)
+{
+	int d = a.stripe_sectors + a.dirty_sectors;
 
 	return d ? max(0, ca->mi.bucket_size - d) : 0;
 }
 
-static inline unsigned bch2_bucket_sectors_unstriped(struct bch_alloc_v4 a)
+static inline s64 bch2_bucket_sectors_unstriped(struct bch_alloc_v4 a)
 {
 	return a.data_type == BCH_DATA_stripe ? a.dirty_sectors : 0;
 }
@@ -277,6 +291,9 @@ static inline bool bkey_is_alloc(const struct bkey *k)
 
 int bch2_alloc_read(struct bch_fs *);
 
+int bch2_alloc_key_to_dev_counters(struct btree_trans *, struct bch_dev *,
+				   const struct bch_alloc_v4 *,
+				   const struct bch_alloc_v4 *, unsigned);
 int bch2_trigger_alloc(struct btree_trans *, enum btree_id, unsigned,
 		       struct bkey_s_c, struct bkey_s,
 		       enum btree_iter_update_trigger_flags);