[PATCH v2] erofs: relax sanity check for tail pclusters due to ztailpacking

[Gao Xiang <hsiangkao@linux.alibaba.com>]

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 pcluster fallback instead of reporting corruption
incorrectly.

Reported-by: Yifan Zhao <zhaoyifan28@huawei.com>
Reported-by: Alberto Salvia Novella <es20490446e@gmail.com>
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@linux.alibaba.com>
---
v2:
 - Drop ztailpacking sb feature check since it might not be set for
   single-file ztailpacking fallback images.

 fs/erofs/zmap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index bab521613552..5811556a7b71 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -732,7 +732,8 @@ 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_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