linux-kernel - [PATCH 2/2] fs: nfs: dir.c: Fix sparse error

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Message-Id: <20191206151640.10966-1-madhuparnabhowmik04@gmail.com>
Date:   Fri,  6 Dec 2019 20:46:40 +0530
From:   madhuparnabhowmik04@...il.com
To:     trond.myklebust@...merspace.com, anna.schumaker@...app.com,
        joel@...lfernandes.org
Cc:     linux-nfs@...r.kernel.org, rcu@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org,
        Madhuparna Bhowmik <madhuparnabhowmik04@...il.com>
Subject: [PATCH 2/2] fs: nfs: dir.c: Fix sparse error

From: Madhuparna Bhowmik <madhuparnabhowmik04@...il.com>

This patch fixes the following errors:
fs/nfs/dir.c:2353:14: error: incompatible types in comparison expression (different address spaces):
fs/nfs/dir.c:2353:14:    struct list_head [noderef] <asn:4> *
fs/nfs/dir.c:2353:14:    struct list_head *

caused due to directly accessing the prev pointer of
a RCU protected list.
Accessing the pointer using the macro list_prev_rcu() fixes this error.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@...il.com>
---
 fs/nfs/dir.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index e180033e35cf..2035254cc283 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2350,7 +2350,7 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
 	rcu_read_lock();
 	if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
 		goto out;
-	lh = rcu_dereference(nfsi->access_cache_entry_lru.prev);
+	lh = rcu_dereference(list_prev_rcu(&nfsi->access_cache_entry_lru));
 	cache = list_entry(lh, struct nfs_access_entry, lru);
 	if (lh == &nfsi->access_cache_entry_lru ||
 	    cred != cache->cred)
-- 
2.17.1