erofs: fix up inplace decompression success rate

Partial decompression should be checked after updating length.
It's a new regression when introducing multi-reference pclusters.

Fixes: 2bfab9c0edac ("erofs: record the longest decompressed size in this round")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221014064915.8103-1-hsiangkao@linux.alibaba.com

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 4553be6..c7f24fc 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -813,15 +813,14 @@ retry:
        ++spiltted;
        if (fe->pcl->pageofs_out != (map->m_la & ~PAGE_MASK))
                fe->pcl->multibases = true;
-
-       if ((map->m_flags & EROFS_MAP_FULL_MAPPED) &&
-           !(map->m_flags & EROFS_MAP_PARTIAL_REF) &&
-           fe->pcl->length == map->m_llen)
-               fe->pcl->partial = false;
        if (fe->pcl->length < offset + end - map->m_la) {
                fe->pcl->length = offset + end - map->m_la;
                fe->pcl->pageofs_out = map->m_la & ~PAGE_MASK;
        }
+       if ((map->m_flags & EROFS_MAP_FULL_MAPPED) &&
+           !(map->m_flags & EROFS_MAP_PARTIAL_REF) &&
+           fe->pcl->length == map->m_llen)
+               fe->pcl->partial = false;
 next_part:
        /* shorten the remaining extent to update progress */
        map->m_llen = offset + cur - map->m_la;