bcachefs: btree read retry fixes

Fix btree node read retries after validate errors:

__btree_err() is the wrong place to flag a topology error: that is done
by btree_lost_data().

Additionally, some calls to bch2_bkey_pick_read_device() were not
updated in the 6.16 rework for improved log messages; we were failing to
signal that we still had a retry.

Cc: Nikita Ofitserov <[email protected]>
Cc: Alan Huang <[email protected]>
Reported-and-tested-by: Edoardo Codeglia <[email protected]>
Signed-off-by: Kent Overstreet <[email protected]>

Author: Kent Overstreet

fs/bcachefs/btree_io.c

@@ -568,9 +568,9 @@ static int __btree_err(int ret,
 		bch2_mark_btree_validate_failure(failed, ca->dev_idx);
 
 		struct extent_ptr_decoded pick;
-		have_retry = !bch2_bkey_pick_read_device(c,
+		have_retry = bch2_bkey_pick_read_device(c,
 					bkey_i_to_s_c(&b->key),
-					failed, &pick, -1);
+					failed, &pick, -1) == 1;
 	}
 
 	if (!have_retry && ret == -BCH_ERR_btree_node_read_err_want_retry)
@@ -615,7 +615,6 @@ static int __btree_err(int ret,
 			goto out;
 		case -BCH_ERR_btree_node_read_err_bad_node:
 			prt_str(&out, ", ");
-			ret = __bch2_topology_error(c, &out);
 			break;
 		}
 
@@ -644,7 +643,6 @@ static int __btree_err(int ret,
 		goto out;
 	case -BCH_ERR_btree_node_read_err_bad_node:
 		prt_str(&out, ", ");
-		ret = __bch2_topology_error(c, &out);
 		break;
 	}
 print:
@@ -1408,7 +1406,7 @@ static void btree_node_read_work(struct work_struct *work)
 		ret = bch2_bkey_pick_read_device(c,
 					bkey_i_to_s_c(&b->key),
 					&failed, &rb->pick, -1);
-		if (ret) {
+		if (ret <= 0) {
 			set_btree_node_read_error(b);
 			break;
 		}

fs/bcachefs/errcode.h

@@ -282,7 +282,6 @@
 	x(EIO,				sb_not_downgraded)			\
 	x(EIO,				btree_node_write_all_failed)		\
 	x(EIO,				btree_node_read_error)			\
-	x(EIO,				btree_node_read_validate_error)		\
 	x(EIO,				btree_need_topology_repair)		\
 	x(EIO,				bucket_ref_update)			\
 	x(EIO,				trigger_alloc)				\

fs/bcachefs/error.c

@@ -103,7 +103,7 @@ int __bch2_topology_error(struct bch_fs *c, struct printbuf *out)
 		return bch_err_throw(c, btree_need_topology_repair);
 	} else {
 		return bch2_run_explicit_recovery_pass(c, out, BCH_RECOVERY_PASS_check_topology, 0) ?:
-			bch_err_throw(c, btree_node_read_validate_error);
+			bch_err_throw(c, btree_need_topology_repair);
 	}
 }