jbd2: track more dependencies on transaction commit

So far we were tracking only dependency on transaction commit due to
starting a new handle (which may require commit to start a new
transaction). Now add tracking also for other cases where we wait for
transaction commit. This way lockdep can catch deadlocks e. g. because we
call jbd2_journal_stop() for a synchronous handle with some locks held
which rank below transaction start.

Signed-off-by: Jan Kara <[e-mail]>
Signed-off-by: Theodore Ts'o <[e-mail]>

fs/jbd2/journal.c

···
 {
 	int err = 0;
 
+	jbd2_might_wait_for_commit(journal);
 	read_lock(&journal->j_state_lock);
 #ifdef CONFIG_JBD2_DEBUG
 	if (!tid_geq(journal->j_commit_request, tid)) {

fs/jbd2/transaction.c

···
 	int needed;
 	int total = blocks + rsv_blocks;
 
+	jbd2_might_wait_for_commit(journal);
+
 	/*
 	 * If the current transaction is locked down for commit, wait
 	 * for the lock to be released.
···
 void jbd2_journal_lock_updates(journal_t *journal)
 {
 	DEFINE_WAIT(wait);
+
+	jbd2_might_wait_for_commit(journal);
 
 	write_lock(&journal->j_state_lock);
 	++journal->j_barrier_count;

include/linux/jbd2.h

···
 #endif
 };
 
+#define jbd2_might_wait_for_commit(j) \
+	do { \
+		rwsem_acquire(&j->j_trans_commit_map, 0, 0, _THIS_IP_); \
+		rwsem_release(&j->j_trans_commit_map, 1, _THIS_IP_); \
+	} while (0)
+
 /* journal feature predicate functions */
 #define JBD2_FEATURE_COMPAT_FUNCS(name, flagname) \
 static inline bool jbd2_has_feature_##name(journal_t *j) \