fixup bcachefs: New on disk format: Backpointers

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

fs/bcachefs/backpointers.c

@@ -5,6 +5,7 @@
 #include "backpointers.h"
 #include "btree_cache.h"
 #include "btree_update.h"
+#include "btree_write_buffer.h"
 #include "error.h"
 
 #include <linux/mm.h>
@@ -553,7 +554,8 @@ static int check_bp_exists(struct btree_trans *trans,
 			   struct bch_backpointer bp,
 			   struct bkey_s_c orig_k,
 			   struct bpos bucket_start,
-			   struct bpos bucket_end)
+			   struct bpos bucket_end,
+			   struct bpos *last_flushed_pos)
 {
 	struct bch_fs *c = trans->c;
 	struct btree_iter alloc_iter, bp_iter = { NULL };
@@ -597,8 +599,15 @@ static int check_bp_exists(struct btree_trans *trans,
 		goto err;
 
 	if (bp_k.k->type != KEY_TYPE_backpointer ||
-	    memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp)))
+	    memcmp(bkey_s_c_to_backpointer(bp_k).v, &bp, sizeof(bp))) {
+		if (!bpos_eq(*last_flushed_pos, orig_k.k->p)) {
+			*last_flushed_pos = orig_k.k->p;
+			ret = bch2_btree_write_buffer_flush_sync(trans) ?:
+				-BCH_ERR_transaction_restart_write_buffer_flush;
+			goto out;
+		}
 		goto missing;
+	}
 out:
 err:
 fsck_err:
@@ -607,6 +616,7 @@ static int check_bp_exists(struct btree_trans *trans,
 	printbuf_exit(&buf);
 	return ret;
 missing:
+
 	prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 	       bch2_btree_ids[bp.btree_id], bp.level);
 	bch2_bkey_val_to_text(&buf, c, orig_k);
@@ -628,7 +638,8 @@ static int check_bp_exists(struct btree_trans *trans,
 static int check_extent_to_backpointers(struct btree_trans *trans,
 					struct btree_iter *iter,
 					struct bpos bucket_start,
-					struct bpos bucket_end)
+					struct bpos bucket_end,
+					struct bpos *last_flushed_pos)
 {
 	struct bch_fs *c = trans->c;
 	struct bkey_ptrs_c ptrs;
@@ -655,7 +666,9 @@ static int check_extent_to_backpointers(struct btree_trans *trans,
 		bch2_extent_ptr_to_bp(c, iter->btree_id, iter->path->level,
 				      k, p, &bucket_pos, &bp);
 
-		ret = check_bp_exists(trans, bucket_pos, bp, k, bucket_start, bucket_end);
+		ret = check_bp_exists(trans, bucket_pos, bp, k,
+				      bucket_start, bucket_end,
+				      last_flushed_pos);
 		if (ret)
 			return ret;
 	}
@@ -666,7 +679,8 @@ static int check_extent_to_backpointers(struct btree_trans *trans,
 static int check_btree_root_to_backpointers(struct btree_trans *trans,
 					    enum btree_id btree_id,
 					    struct bpos bucket_start,
-					    struct bpos bucket_end)
+					    struct bpos bucket_end,
+					    struct bpos *last_flushed_pos)
 {
 	struct bch_fs *c = trans->c;
 	struct btree_iter iter;
@@ -698,7 +712,9 @@ static int check_btree_root_to_backpointers(struct btree_trans *trans,
 		bch2_extent_ptr_to_bp(c, iter.btree_id, iter.path->level + 1,
 				      k, p, &bucket_pos, &bp);
 
-		ret = check_bp_exists(trans, bucket_pos, bp, k, bucket_start, bucket_end);
+		ret = check_bp_exists(trans, bucket_pos, bp, k,
+				      bucket_start, bucket_end,
+				      last_flushed_pos);
 		if (ret)
 			goto err;
 	}
@@ -778,6 +794,7 @@ static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 {
 	struct btree_iter iter;
 	enum btree_id btree_id;
+	struct bpos last_flushed_pos = SPOS_MAX;
 	int ret = 0;
 
 	for (btree_id = 0; btree_id < BTREE_ID_NR; btree_id++) {
@@ -793,7 +810,8 @@ static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 					BTREE_INSERT_LAZY_RW|
 					BTREE_INSERT_NOFAIL,
 					check_extent_to_backpointers(trans, &iter,
-								bucket_start, bucket_end));
+								bucket_start, bucket_end,
+								&last_flushed_pos));
 			if (ret)
 				break;
 		} while (!bch2_btree_iter_advance(&iter));
@@ -807,7 +825,8 @@ static int bch2_check_extents_to_backpointers_pass(struct btree_trans *trans,
 				BTREE_INSERT_LAZY_RW|
 				BTREE_INSERT_NOFAIL,
 				check_btree_root_to_backpointers(trans, btree_id,
-							bucket_start, bucket_end));
+							bucket_start, bucket_end,
+							&last_flushed_pos));
 		if (ret)
 			break;
 	}