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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <Anna.Schumaker@Netapp.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 076/306] NFSv4/pNFS: Always allow update of a zero valued layout barrier
Date:   Thu, 16 Sep 2021 17:57:01 +0200
Message-Id: <20210916155756.646922134@linuxfoundation.org>
In-Reply-To: <20210916155753.903069397@linuxfoundation.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit 45baadaad7bf9183651fb74f4ed1200da48505a5 ]

A zero value for the layout barrier indicates that it has been cleared
(since seqid '0' is an illegal value), so we should always allow it to
be updated.

Fixes: d29b468da4f9 ("pNFS/NFSv4: Improve rejection of out-of-order layouts")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfs/pnfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index fef0537d15b0..741b6283ac9c 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -335,7 +335,7 @@ static bool pnfs_seqid_is_newer(u32 s1, u32 s2)
 
 static void pnfs_barrier_update(struct pnfs_layout_hdr *lo, u32 newseq)
 {
-	if (pnfs_seqid_is_newer(newseq, lo->plh_barrier))
+	if (pnfs_seqid_is_newer(newseq, lo->plh_barrier) || !lo->plh_barrier)
 		lo->plh_barrier = newseq;
 }
 
-- 
2.30.2