[PATCH] erofs: relax sanity check for tail pclusters on ztailpacking images

[Gao Xiang]

If the tail data can be inlined into the inode meta block, it should
be converted into a regular tail pcluster.

In principle, it should be converted into an uncompressed pcluster if
there is not enough gain to use compression (map->m_llen < map->m_plen);
but since there are various shipped images, relax the condition for
ztailpacking tail pclusters instead of reporting corruption incorrectly.

Reported-by: Yifan Zhao <zhaoyifan28@xxxxxxxxxx>
Reported-by: Alberto Salvia Novella <es20490446e@xxxxxxxxx>
Closes: https://github.com/erofs/erofs-utils/issues/51
Fixes: a5242d37c83a ("erofs: error out obviously illegal extents in advance")
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
---
 fs/erofs/zmap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index bab521613552..f6b0172a6acc 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -732,7 +732,9 @@ static int z_erofs_map_sanity_check(struct inode *inode,
 				  map->m_algorithmformat, EROFS_I(inode)->nid);
 			return -EFSCORRUPTED;
 		}
-		if (EROFS_MAP_FULL(map->m_flags) && map->m_llen < map->m_plen) {
+		if (EROFS_MAP_FULL(map->m_flags) && map->m_llen < map->m_plen &&
+		    (map->m_la + map->m_llen < inode->i_size ||
+		     !erofs_sb_has_ztailpacking(sbi))) {
 			erofs_err(inode->i_sb, "too much compressed data @ la %llu of nid %llu",
 				  map->m_la, EROFS_I(inode)->nid);
 			return -EFSCORRUPTED;
-- 
2.43.5