bcachefs: Fix bch2_journal_meta()

This patch ensures that the journal entry written gets written as flush
entry, which is important for the shutdown path - the last entry written
needs to be a flush entry.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/journal.c

@@ -641,6 +641,7 @@ int bch2_journal_flush_seq(struct journal *j, u64 seq)
 
 int bch2_journal_meta(struct journal *j)
 {
+	struct journal_buf *buf;
 	struct journal_res res;
 	int ret;
 
@@ -650,6 +651,10 @@ int bch2_journal_meta(struct journal *j)
 	if (ret)
 		return ret;
 
+	buf = j->buf + (res.seq & JOURNAL_BUF_MASK);
+	buf->must_flush = true;
+	set_bit(JOURNAL_NEED_WRITE, &j->flags);
+
 	bch2_journal_res_put(j, &res);
 
 	return bch2_journal_flush_seq(j, res.seq);

fs/bcachefs/journal_io.c

@@ -1445,7 +1445,7 @@ void bch2_journal_write(struct closure *cl)
 	SET_JSET_BIG_ENDIAN(jset, CPU_BIG_ENDIAN);
 	SET_JSET_CSUM_TYPE(jset, bch2_meta_checksum_type(c));
 
-	if (journal_entry_empty(jset))
+	if (!JSET_NO_FLUSH(jset) && journal_entry_empty(jset))
 		j->last_empty_seq = le64_to_cpu(jset->seq);
 
 	if (bch2_csum_type_is_encryption(JSET_CSUM_TYPE(jset)))

fs/bcachefs/sysfs.c

@@ -131,7 +131,6 @@ do {									\
 		return strtoi_h(buf, &var) ?: (ssize_t) size;		\
 } while (0)
 
-write_attribute(trigger_journal_flush);
 write_attribute(trigger_gc);
 write_attribute(prune_cache);
 rw_attribute(btree_gc_periodic);
@@ -482,9 +481,6 @@ STORE(bch2_fs)
 
 	/* Debugging: */
 
-	if (attr == &sysfs_trigger_journal_flush)
-		bch2_journal_meta(&c->journal);
-
 	if (attr == &sysfs_trigger_gc) {
 		/*
 		 * Full gc is currently incompatible with btree key cache:
@@ -574,7 +570,6 @@ struct attribute *bch2_fs_internal_files[] = {
 	&sysfs_io_timers_read,
 	&sysfs_io_timers_write,
 
-	&sysfs_trigger_journal_flush,
 	&sysfs_trigger_gc,
 	&sysfs_prune_cache,