ext4_journal: handle trans_id wrapping around cases

diff --git a/src/ext4_journal.c b/src/ext4_journal.c
index 9fe984e1d8b45c6e1f3a3abe1fbe3ac5df18ec2e..c68d5a14d81f9e018cc342475c1c5f691c1d7016 100644 (file)
--- a/src/ext4_journal.c
+++ b/src/ext4_journal.c
@@ -103,6 +103,12 @@ do {                                                                       \
                var -= (jbd_get32((sb), maxlen) - jbd_get32((sb), first));      \
 } while (0)
 
+static inline int32_t
+trans_id_diff(uint32_t x, uint32_t y)
+{
+       int32_t diff = x - y;
+       return (diff >= 0);
+}
 
 static int
 jbd_revoke_entry_cmp(struct revoke_entry *a, struct revoke_entry *b)
@@ -878,7 +884,7 @@ static void jbd_replay_block_tags(struct jbd_fs *jbd_fs,
         * is equal or greater than that in revoke entry.*/
        revoke_entry = jbd_revoke_entry_lookup(info, block);
        if (revoke_entry &&
-           arg->this_trans_id < revoke_entry->trans_id)
+           trans_id_diff(arg->this_trans_id, revoke_entry->trans_id) < 0)
                return;
 
        ext4_dbg(DEBUG_JBD,
@@ -1066,7 +1072,7 @@ static int jbd_iterate_log(struct jbd_fs *jbd_fs,
                 * we will stop when we reach the end of
                 * the journal.*/
                if (action != ACTION_SCAN)
-                       if (this_trans_id > info->last_trans_id) {
+                       if (trans_id_diff(this_trans_id, info->last_trans_id) > 0) {
                                log_end = true;
                                continue;
                        }
@@ -1176,7 +1182,7 @@ static int jbd_iterate_log(struct jbd_fs *jbd_fs,
        if (r == EOK && action == ACTION_SCAN) {
                /* We have finished scanning the journal. */
                info->start_trans_id = start_trans_id;
-               if (this_trans_id > start_trans_id)
+               if (trans_id_diff(this_trans_id, start_trans_id) > 0)
                        info->last_trans_id = this_trans_id - 1;
                else
                        info->last_trans_id = this_trans_id;