4 files changed, 45 insertions, 22 deletions

diff --git a/fs/bcachefs/btree_locking.c b/fs/bcachefs/btree_locking.c
index ad6e364980f3..3973e8d7e6da 100644
--- a/fs/bcachefs/btree_locking.c
+++ b/fs/bcachefs/btree_locking.c
@@ -138,7 +138,29 @@ static noinline int break_cycle(struct lock_graph *g)
 		return abort_lock(g, i);
 	}
 
-	BUG();
+	{
+		struct bch_fs *c = g->g->trans->c;
+		struct printbuf buf = PRINTBUF;
+
+		bch_err(c, "cycle of nofail locks");
+
+		for (i = g->g; i < g->g + g->nr; i++) {
+			struct btree_trans *trans = i->trans;
+
+			bch2_btree_trans_to_text(&buf, trans);
+
+			prt_printf(&buf, "backtrace:");
+			prt_newline(&buf);
+			printbuf_indent_add(&buf, 2);
+			bch2_prt_backtrace(&buf, trans->locking_wait.task);
+			printbuf_indent_sub(&buf, 2);
+			prt_newline(&buf);
+		}
+
+		bch2_print_string_as_lines(KERN_ERR, buf.buf);
+		printbuf_exit(&buf);
+		BUG();
+	}
 }
 
 static void lock_graph_pop(struct lock_graph *g)
diff --git a/fs/bcachefs/debug.c b/fs/bcachefs/debug.c
index c7d558381388..7abc707d2f38 100644
--- a/fs/bcachefs/debug.c
+++ b/fs/bcachefs/debug.c
@@ -501,26 +501,6 @@ static const struct file_operations cached_btree_nodes_ops = {
 };
 
 #ifdef CONFIG_BCACHEFS_DEBUG_TRANSACTIONS
-static int prt_backtrace(struct printbuf *out, struct task_struct *task)
-{
-	unsigned long entries[32];
-	unsigned i, nr_entries;
-	int ret;
-
-	ret = down_read_killable(&task->signal->exec_update_lock);
-	if (ret)
-		return ret;
-
-	nr_entries = stack_trace_save_tsk(task, entries, ARRAY_SIZE(entries), 0);
-	for (i = 0; i < nr_entries; i++) {
-		prt_printf(out, "[<0>] %pB", (void *)entries[i]);
-		prt_newline(out);
-	}
-
-	up_read(&task->signal->exec_update_lock);
-	return 0;
-}
-
 static ssize_t bch2_btree_transactions_read(struct file *file, char __user *buf,
 					    size_t size, loff_t *ppos)
 {
@@ -547,7 +527,7 @@ static ssize_t bch2_btree_transactions_read(struct file *file, char __user *buf,
 		prt_printf(&i->buf, "backtrace:");
 		prt_newline(&i->buf);
 		printbuf_indent_add(&i->buf, 2);
-		prt_backtrace(&i->buf, trans->locking_wait.task);
+		bch2_prt_backtrace(&i->buf, trans->locking_wait.task);
 		printbuf_indent_sub(&i->buf, 2);
 		prt_newline(&i->buf);
 
diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
index 477c260de50b..bf529bb137ed 100644
--- a/fs/bcachefs/util.c
+++ b/fs/bcachefs/util.c
@@ -265,6 +265,26 @@ void bch2_print_string_as_lines(const char *prefix, const char *lines)
 	console_unlock();
 }
 
+int bch2_prt_backtrace(struct printbuf *out, struct task_struct *task)
+{
+	unsigned long entries[32];
+	unsigned i, nr_entries;
+	int ret;
+
+	ret = down_read_killable(&task->signal->exec_update_lock);
+	if (ret)
+		return ret;
+
+	nr_entries = stack_trace_save_tsk(task, entries, ARRAY_SIZE(entries), 0);
+	for (i = 0; i < nr_entries; i++) {
+		prt_printf(out, "[<0>] %pB", (void *)entries[i]);
+		prt_newline(out);
+	}
+
+	up_read(&task->signal->exec_update_lock);
+	return 0;
+}
+
 /* time stats: */
 
 #ifndef CONFIG_BCACHEFS_NO_LATENCY_ACCT
diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
index a16f8bb9d415..3b0090faef4d 100644
--- a/fs/bcachefs/util.h
+++ b/fs/bcachefs/util.h
@@ -383,6 +383,7 @@ u64 bch2_read_flag_list(char *, const char * const[]);
 void bch2_prt_u64_binary(struct printbuf *, u64, unsigned);
 
 void bch2_print_string_as_lines(const char *prefix, const char *lines);
+int bch2_prt_backtrace(struct printbuf *, struct task_struct *);
 
 #define NR_QUANTILES	15
 #define QUANTILE_IDX(i)	inorder_to_eytzinger0(i, NR_QUANTILES)