linux-kernel - [PATCH] erofs: silence warnings related to impossible m

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Message-Id: <20220310173448.19962-1-hsiangkao@linux.alibaba.com>
Date:   Fri, 11 Mar 2022 01:34:48 +0800
From:   Gao Xiang <hsiangkao@...ux.alibaba.com>
To:     linux-erofs@...ts.ozlabs.org, Chao Yu <chao@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Gao Xiang <hsiangkao@...ux.alibaba.com>,
        kernel test robot <lkp@...el.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH] erofs: silence warnings related to impossible m_plen

Dan reported two smatch warnings [1],
.. warn: should '1 << lclusterbits' be a 64 bit type?
.. warn: should 'm->compressedlcs << lclusterbits' be a 64 bit type?

In practice, m_plen cannot be more than 1MiB due to on-disk constraint
for the compression mode, so we're always safe here.

In order to make static analyzers happy and don't report again,
let's silence them instead.

[1] https://lore.kernel.org/r/202203091002.lJVzsX6e-lkp@intel.com

Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
---
 fs/erofs/zmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 361b1d6e4bf9..b4059b9c3bac 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -494,7 +494,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 	     !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1)) ||
 	    ((m->headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) &&
 	     !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_2))) {
-		map->m_plen = 1 << lclusterbits;
+		map->m_plen = 1ULL << lclusterbits;
 		return 0;
 	}
 	lcn = m->lcn + 1;
@@ -540,7 +540,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 		return -EFSCORRUPTED;
 	}
 out:
-	map->m_plen = m->compressedlcs << lclusterbits;
+	map->m_plen = (u64)m->compressedlcs << lclusterbits;
 	return 0;
 err_bonus_cblkcnt:
 	erofs_err(m->inode->i_sb,
-- 
2.24.4