bcachefs: Ensure we don't use a blacklisted journal seq

Different versions differ on the size of the blacklist range; it is
theoretically possible that we could end up with blacklisted journal
sequence numbers newer than the newest seq we find in the journal, and
pick a new start seq that's blacklisted.

Explicitly check for this in bch2_fs_journal_start().

Signed-off-by: Kent Overstreet <[email protected]>

Author: Kent Overstreet

fs/bcachefs/journal.c

@@ -415,7 +415,7 @@ static int journal_entry_open(struct journal *j)
 	if (atomic64_read(&j->seq) - j->seq_write_started == JOURNAL_STATE_BUF_NR)
 		return -BCH_ERR_journal_max_open;
 
-	if (journal_cur_seq(j) >= JOURNAL_SEQ_MAX) {
+	if (unlikely(journal_cur_seq(j) >= JOURNAL_SEQ_MAX)) {
 		bch_err(c, "cannot start: journal seq overflow");
 		if (bch2_fs_emergency_read_only_locked(c))
 			bch_err(c, "fatal error - emergency read only");
@@ -459,6 +459,14 @@ static int journal_entry_open(struct journal *j)
 	atomic64_inc(&j->seq);
 	journal_pin_list_init(fifo_push_ref(&j->pin), 1);
 
+	if (unlikely(bch2_journal_seq_is_blacklisted(c, journal_cur_seq(j), false))) {
+		bch_err(c, "attempting to open blacklisted journal seq %llu",
+			journal_cur_seq(j));
+		if (bch2_fs_emergency_read_only_locked(c))
+			bch_err(c, "fatal error - emergency read only");
+		return -BCH_ERR_journal_shutdown;
+	}
+
 	BUG_ON(j->pin.back - 1 != atomic64_read(&j->seq));
 
 	BUG_ON(j->buf + (journal_cur_seq(j) & JOURNAL_BUF_MASK) != buf);
@@ -1415,6 +1423,13 @@ int bch2_fs_journal_start(struct journal *j, u64 cur_seq)
 	bool had_entries = false;
 	u64 last_seq = cur_seq, nr, seq;
 
+	/*
+	 *
+	 * XXX pick most recent non blacklisted sequence number
+	 */
+
+	cur_seq = max(cur_seq, bch2_journal_last_blacklisted_seq(c));
+
 	if (cur_seq >= JOURNAL_SEQ_MAX) {
 		bch_err(c, "cannot start: journal seq overflow");
 		return -EINVAL;

fs/bcachefs/journal_seq_blacklist.c

@@ -130,6 +130,16 @@ bool bch2_journal_seq_is_blacklisted(struct bch_fs *c, u64 seq,
 	return true;
 }
 
+u64 bch2_journal_last_blacklisted_seq(struct bch_fs *c)
+{
+	struct journal_seq_blacklist_table *t = c->journal_seq_blacklist_table;
+
+	if (!t || !t->nr)
+		return 0;
+
+	return t->entries[eytzinger0_last(t->nr)].end - 1;
+}
+
 int bch2_blacklist_table_initialize(struct bch_fs *c)
 {
 	struct bch_sb_field_journal_seq_blacklist *bl =

fs/bcachefs/journal_seq_blacklist.h

@@ -12,6 +12,7 @@ blacklist_nr_entries(struct bch_sb_field_journal_seq_blacklist *bl)
 }
 
 bool bch2_journal_seq_is_blacklisted(struct bch_fs *, u64, bool);
+u64 bch2_journal_last_blacklisted_seq(struct bch_fs *);
 int bch2_journal_seq_blacklist_add(struct bch_fs *c, u64, u64);
 int bch2_blacklist_table_initialize(struct bch_fs *);