bcachefs: Fix unlocked access to c->disk_sb.sb in bch2_replicas_entry_validate()

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/journal_io.c

@@ -605,7 +605,7 @@ static int journal_entry_data_usage_validate(struct bch_fs *c,
 		goto out;
 	}
 
-	if (journal_entry_err_on(bch2_replicas_entry_validate(&u->r, c->disk_sb.sb, &err),
+	if (journal_entry_err_on(bch2_replicas_entry_validate(&u->r, c, &err),
 				 c, version, jset, entry,
 				 journal_entry_data_usage_bad_size,
 				 "invalid journal entry usage: %s", err.buf)) {

fs/bcachefs/replicas.c

@@ -66,7 +66,7 @@ void bch2_replicas_entry_to_text(struct printbuf *out,
 	prt_printf(out, "]");
 }
 
-int bch2_replicas_entry_validate(struct bch_replicas_entry_v1 *r,
+static int bch2_replicas_entry_validate_locked(struct bch_replicas_entry_v1 *r,
 					       struct bch_sb *sb,
 					       struct printbuf *err)
 {
@@ -94,6 +94,16 @@ int bch2_replicas_entry_validate(struct bch_replicas_entry_v1 *r,
 	return -BCH_ERR_invalid_replicas_entry;
 }
 
+int bch2_replicas_entry_validate(struct bch_replicas_entry_v1 *r,
+				 struct bch_fs *c,
+				 struct printbuf *err)
+{
+	mutex_lock(&c->sb_lock);
+	int ret = bch2_replicas_entry_validate_locked(r, c->disk_sb.sb, err);
+	mutex_unlock(&c->sb_lock);
+	return ret;
+}
+
 void bch2_cpu_replicas_to_text(struct printbuf *out,
 			       struct bch_replicas_cpu *r)
 {
@@ -676,7 +686,7 @@ static int bch2_cpu_replicas_validate(struct bch_replicas_cpu *cpu_r,
 		struct bch_replicas_entry_v1 *e =
 			cpu_replicas_entry(cpu_r, i);
 
-		int ret = bch2_replicas_entry_validate(e, sb, err);
+		int ret = bch2_replicas_entry_validate_locked(e, sb, err);
 		if (ret)
 			return ret;
 

fs/bcachefs/replicas.h

@@ -10,7 +10,7 @@ void bch2_replicas_entry_sort(struct bch_replicas_entry_v1 *);
 void bch2_replicas_entry_to_text(struct printbuf *,
 				 struct bch_replicas_entry_v1 *);
 int bch2_replicas_entry_validate(struct bch_replicas_entry_v1 *,
-				 struct bch_sb *, struct printbuf *);
+				 struct bch_fs *, struct printbuf *);
 void bch2_cpu_replicas_to_text(struct printbuf *, struct bch_replicas_cpu *);
 
 static inline struct bch_replicas_entry_v1 *