bcachefs: mark journal replicas before journal write submission

The journal write submission path marks the associated replica
entries for journal data in journal_write_done(), which is just
after journal write bio submission. This creates a small window
where journal entries might have been written out, but the
associated replica is not marked such that recovery does not know
that the associated device contains journal data.

Move the replica marking a bit earlier in the write path such that
recovery is guaranteed to recognize that the device contains journal
data in the event of a crash.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/journal_io.c

@@ -1462,7 +1462,6 @@ static void journal_write_done(struct closure *cl)
 	struct journal *j = container_of(cl, struct journal, io);
 	struct bch_fs *c = container_of(j, struct bch_fs, journal);
 	struct journal_buf *w = journal_last_unwritten_buf(j);
-	struct bch_replicas_padded replicas;
 	union journal_res_state old, new;
 	u64 v, seq;
 	int err = 0;
@@ -1474,13 +1473,7 @@ static void journal_write_done(struct closure *cl)
 	if (!w->devs_written.nr) {
 		bch_err(c, "unable to write journal to sufficient devices");
 		err = -EIO;
-	} else {
-		bch2_devlist_to_replicas(&replicas.e, BCH_DATA_journal,
-					 w->devs_written);
-		if (bch2_mark_replicas(c, &replicas.e))
-			err = -EIO;
 	}
-
 	if (err)
 		bch2_fatal_error(c);
 
@@ -1672,6 +1665,7 @@ void bch2_journal_write(struct closure *cl)
 	struct bch_fs *c = container_of(j, struct bch_fs, journal);
 	struct bch_dev *ca;
 	struct journal_buf *w = journal_last_unwritten_buf(j);
+	struct bch_replicas_padded replicas;
 	struct jset_entry *start, *end;
 	struct jset *jset;
 	struct bio *bio;
@@ -1822,9 +1816,7 @@ void bch2_journal_write(struct closure *cl)
 		bch_err(c, "Unable to allocate journal write:\n%s",
 			journal_debug_buf.buf);
 		printbuf_exit(&journal_debug_buf);
-		bch2_fatal_error(c);
-		continue_at(cl, journal_write_done, c->io_complete_wq);
-		return;
+		goto err;
 	}
 
 	w->devs_written = bch2_bkey_devs(bkey_i_to_s_c(&w->key));
@@ -1838,6 +1830,16 @@ void bch2_journal_write(struct closure *cl)
 	if (nr_rw_members > 1)
 		w->separate_flush = true;
 
+	/*
+	 * Mark journal replicas before we submit the write to guarantee
+	 * recovery will find the journal entries after a crash.
+	 */
+	bch2_devlist_to_replicas(&replicas.e, BCH_DATA_journal,
+				 w->devs_written);
+	ret = bch2_mark_replicas(c, &replicas.e);
+	if (ret)
+		goto err;
+
 	if (!JSET_NO_FLUSH(jset) && w->separate_flush) {
 		for_each_rw_member(ca, c, i) {
 			percpu_ref_get(&ca->io_ref);