[PATCH 6/9] erofs-utils: lib: handle NONHEAD !delta[1] lclusters gracefully

[Gao Xiang]

Source kernel commit: 0bc8061ffc733a0a246b8689b2d32a3e9204f43c
Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
---
 lib/zmap.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/lib/zmap.c b/lib/zmap.c
index c79424b..c48eba4 100644
--- a/lib/zmap.c
+++ b/lib/zmap.c
@@ -232,7 +232,7 @@ static int z_erofs_load_compact_lcluster(struct z_erofs_maprecorder *m,
 	erofs_blk_t eblk;
 	int err;
 
-	if (lcn >= totalidx)
+	if (lcn >= totalidx || vi->z_logical_clusterbits > 14)
 		return -EINVAL;
 
 	m->lcn = lcn;
@@ -416,7 +416,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
 	u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
 	int err;
 
-	do {
+	while (1) {
 		/* handle the last EOF pcluster (no next HEAD lcluster) */
 		if ((lcn << lclusterbits) >= vi->i_size) {
 			map->m_llen = vi->i_size - map->m_la;
@@ -428,14 +428,16 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
 			return err;
 
 		if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
-			DBG_BUGON(!m->delta[1] &&
-				  m->clusterofs != 1 << lclusterbits);
+			/* work around invalid d1 generated by pre-1.0 mkfs */
+			if (__erofs_unlikely(!m->delta[1])) {
+				m->delta[1] = 1;
+				DBG_BUGON(1);
+			}
 		} else if (m->type == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
 			   m->type == Z_EROFS_LCLUSTER_TYPE_HEAD1 ||
 			   m->type == Z_EROFS_LCLUSTER_TYPE_HEAD2) {
-			/* go on until the next HEAD lcluster */
 			if (lcn != headlcn)
-				break;
+				break;	/* ends at the next HEAD lcluster */
 			m->delta[1] = 1;
 		} else {
 			erofs_err("unknown type %u @ lcn %llu of nid %llu",
@@ -445,8 +447,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
 			return -EOPNOTSUPP;
 		}
 		lcn += m->delta[1];
-	} while (m->delta[1]);
-
+	}
 	map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
 	return 0;
 }
-- 
2.43.5