- mutex_lock(&c->tnc_mutex);
- found = ubifs_lookup_level0(c, key, &znode, &n);
- if (!found) {
- err = -ENOENT;
- goto out;
- } else if (found < 0) {
- err = found;
- goto out;
- }
- zt = &znode->zbranch[n];
- if (is_hash_key(c, key)) {
- /*
- * In this case the leaf node cache gets used, so we pass the
- * address of the zbranch and keep the mutex locked
- */
- err = tnc_read_node_nm(c, zt, node);
- goto out;
- }
- zbr = znode->zbranch[n];
- mutex_unlock(&c->tnc_mutex);
-
- err = ubifs_tnc_read_node(c, &zbr, node);
- return err;
-
-out:
- mutex_unlock(&c->tnc_mutex);
- return err;
+ gced_lnum = c->gced_lnum;
+ smp_rmb();
+ gc_seq2 = c->gc_seq;
+ /* Same seq means no GC */
+ if (gc_seq1 == gc_seq2)
+ return 0;
+ /* Different by more than 1 means we don't know */
+ if (gc_seq1 + 1 != gc_seq2)
+ return 1;
+ /*
+ * We have seen the sequence number has increased by 1. Now we need to
+ * be sure we read the right LEB number, so read it again.
+ */
+ smp_rmb();
+ if (gced_lnum != c->gced_lnum)
+ return 1;
+ /* Finally we can check lnum */
+ if (gced_lnum == lnum)
+ return 1;
+ return 0;