From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Tue, 15 Oct 2024 03:52:51 +0000 (-0400)
Subject: bcachefs: Better in_restart error
X-Git-Tag: v6.14-rc1~204^2~208
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a71a1fac904d89fe6a5a1d407a85de0b078f1dee;p=thirdparty%2Fkernel%2Flinux.git

bcachefs: Better in_restart error

We're ramping up on checking transaction restart handling correctness -
so, in debug mode we now save a backtrace for where the restart was
emitted, which makes it much easier to track down the incorrect
handling.

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

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 98375c66021a3..acf70aaf2fd29 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -1427,9 +1427,17 @@ void __noreturn bch2_trans_restart_error(struct btree_trans *trans, u32 restart_
 
 void __noreturn bch2_trans_in_restart_error(struct btree_trans *trans)
 {
+#ifdef CONFIG_BCACHEFS_DEBUG
+	struct printbuf buf = PRINTBUF;
+	bch2_prt_backtrace(&buf, &trans->last_restarted_trace);
+	panic("in transaction restart: %s, last restarted by\n%s",
+	      bch2_err_str(trans->restarted),
+	      buf.buf);
+#else
 	panic("in transaction restart: %s, last restarted by %pS\n",
 	      bch2_err_str(trans->restarted),
 	      (void *) trans->last_restarted_ip);
+#endif
 }
 
 void __noreturn bch2_trans_unlocked_error(struct btree_trans *trans)
@@ -3287,6 +3295,10 @@ void bch2_trans_put(struct btree_trans *trans)
 	closure_return_sync(&trans->ref);
 	trans->locking_wait.task = NULL;
 
+#ifdef CONFIG_BCACHEFS_DEBUG
+	darray_exit(&trans->last_restarted_trace);
+#endif
+
 	unsigned long *paths_allocated = trans->paths_allocated;
 	trans->paths_allocated	= NULL;
 	trans->paths		= NULL;
diff --git a/fs/bcachefs/btree_iter.h b/fs/bcachefs/btree_iter.h
index dda07a3204880..36899c6b134e5 100644
--- a/fs/bcachefs/btree_iter.h
+++ b/fs/bcachefs/btree_iter.h
@@ -350,6 +350,10 @@ static int btree_trans_restart_ip(struct btree_trans *trans, int err, unsigned l
 
 	trans->restarted = err;
 	trans->last_restarted_ip = ip;
+#ifdef CONFIG_BCACHEFS_DEBUG
+	darray_exit(&trans->last_restarted_trace);
+	bch2_save_backtrace(&trans->last_restarted_trace, current, 0, GFP_NOWAIT);
+#endif
 	return -err;
 }
 
diff --git a/fs/bcachefs/btree_types.h b/fs/bcachefs/btree_types.h
index 4568a41fefaf6..baab5288ecc9b 100644
--- a/fs/bcachefs/btree_types.h
+++ b/fs/bcachefs/btree_types.h
@@ -513,6 +513,9 @@ struct btree_trans {
 	u64			last_begin_time;
 	unsigned long		last_begin_ip;
 	unsigned long		last_restarted_ip;
+#ifdef CONFIG_BCACHEFS_DEBUG
+	bch_stacktrace		last_restarted_trace;
+#endif
 	unsigned long		last_unlock_ip;
 	unsigned long		srcu_lock_time;