[PATCH 20/21] bcachefs: rebalance: erasure_code opt change now handled

We had no existing mechanism for applying/removing erasure coding to
existing data, nothing is being obsoleted.

Like other IO path options, rebalance now ensures that data is stored
correctly according to the current erasure_code option.

Signed-off-by: Kent Overstreet <[email protected]>
---
 fs/bcachefs/rebalance.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/fs/bcachefs/rebalance.c b/fs/bcachefs/rebalance.c
index 29e12dbf3710..525e4d1716c5 100644
--- a/fs/bcachefs/rebalance.c
+++ b/fs/bcachefs/rebalance.c
@@ -593,9 +593,12 @@ static struct bkey_s_c next_rebalance_extent(struct btree_trans *trans,
 	data_opts->target		= opts->background_target;
 	data_opts->write_flags		|= BCH_WRITE_only_specified_devs;
 
+	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+	const union bch_extent_entry *entry;
+	struct extent_ptr_decoded p;
+
 	if (r.need_rb & BIT(BCH_REBALANCE_data_replicas)) {
 		unsigned durability = bch2_bkey_durability(c, k);
-		struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
 		unsigned ptr_bit = 1;
 
 		guard(rcu)();
@@ -609,9 +612,6 @@ static struct bkey_s_c next_rebalance_extent(struct btree_trans *trans,
 
 			data_opts->extra_replicas = opts->data_replicas - durability;
 		} else {
-			const union bch_extent_entry *entry;
-			struct extent_ptr_decoded p;
-
 			bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 				unsigned d = bch2_extent_ptr_durability(c, &p);
 
@@ -635,6 +635,22 @@ static struct bkey_s_c next_rebalance_extent(struct btree_trans *trans,
 		}
 	}
 
+	if (r.need_rb & BIT(BCH_REBALANCE_erasure_code)) {
+		if (opts->erasure_code) {
+			data_opts->extra_replicas = min(data_opts->extra_replicas, 1);
+		} else {
+			unsigned ptr_bit = 1;
+			bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
+				if (p.has_ec) {
+					data_opts->kill_ec_ptrs |= ptr_bit;
+					data_opts->extra_replicas += p.ec.redundancy;
+				}
+
+				ptr_bit <<= 1;
+			}
+		}
+	}
+
 	if (!data_opts->rewrite_ptrs &&
 	    !data_opts->kill_ptrs &&
 	    !data_opts->kill_ec_ptrs &&
-- 
2.50.1