bcachefs: KEY_TYPE_accounting

New key type for the disk space accounting rewrite.

 - Holds a variable sized array of u64s (may be more than one for
   accounting e.g. compressed and uncompressed size, or buckets and
   sectors for a given data type)

 - Updates are deltas, not new versions of the key: this means updates
   to accounting can happen via the btree write buffer, which we'll be
   teaching to accumulate deltas.

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

1 files changed, 52 insertions, 0 deletions

diff --git a/fs/bcachefs/disk_accounting.h b/fs/bcachefs/disk_accounting.h
new file mode 100644
index 000000000000..178ec25b7ef4
--- /dev/null
+++ b/fs/bcachefs/disk_accounting.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHEFS_DISK_ACCOUNTING_H
+#define _BCACHEFS_DISK_ACCOUNTING_H
+
+static inline unsigned bch2_accounting_counters(const struct bkey *k)
+{
+	return bkey_val_u64s(k) - offsetof(struct bch_accounting, d) / sizeof(u64);
+}
+
+static inline void bch2_accounting_accumulate(struct bkey_i_accounting *dst,
+					      struct bkey_s_c_accounting src)
+{
+	EBUG_ON(dst->k.u64s != src.k->u64s);
+
+	for (unsigned i = 0; i < bch2_accounting_counters(&dst->k); i++)
+		dst->v.d[i] += src.v->d[i];
+	if (bversion_cmp(dst->k.version, src.k->version) < 0)
+		dst->k.version = src.k->version;
+}
+
+static inline void bpos_to_disk_accounting_pos(struct disk_accounting_pos *acc, struct bpos p)
+{
+	acc->_pad = p;
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	bch2_bpos_swab(&acc->_pad);
+#endif
+}
+
+static inline struct bpos disk_accounting_pos_to_bpos(struct disk_accounting_pos *k)
+{
+	struct bpos ret = k->_pad;
+
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	bch2_bpos_swab(&ret);
+#endif
+	return ret;
+}
+
+int bch2_accounting_invalid(struct bch_fs *, struct bkey_s_c,
+			    enum bch_validate_flags, struct printbuf *);
+void bch2_accounting_key_to_text(struct printbuf *, struct disk_accounting_pos *);
+void bch2_accounting_to_text(struct printbuf *, struct bch_fs *, struct bkey_s_c);
+void bch2_accounting_swab(struct bkey_s);
+
+#define bch2_bkey_ops_accounting ((struct bkey_ops) {	\
+	.key_invalid	= bch2_accounting_invalid,	\
+	.val_to_text	= bch2_accounting_to_text,	\
+	.swab		= bch2_accounting_swab,		\
+	.min_val_size	= 8,				\
+})
+
+#endif /* _BCACHEFS_DISK_ACCOUNTING_H */