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From:   trondmy@kernel.org
To:     linux-nfs@vger.kernel.org
Subject: [PATCH 1/2] NFSv4/pNFS: Always allow update of a zero valued layout barrier
Date:   Fri, 23 Jul 2021 08:57:20 -0400
Message-Id: <20210723125721.22572-1-trondmy@kernel.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

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>
---
 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 ef14ea0b6ab8..4e69e4e6c416 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;
 }
 
-- 
2.31.1