From 2f8220c16ee0055f7ea541782651b30398752ee4 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Mon, 3 Oct 2016 18:13:20 -0400
Subject: [PATCH] NFS: Fix up read of mirror stats

Need to lock while reading in order to ensure 64-bit reads are correct.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 fs/nfs/flexfilelayout/flexfilelayout.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index f61df1641567..c18afd5cc0bb 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -2250,10 +2250,12 @@ ff_layout_mirror_prepare_stats(struct pnfs_layout_hdr *lo,
 		memcpy(&devinfo->dev_id, &dev->deviceid, NFS4_DEVICEID4_SIZE);
 		devinfo->offset = 0;
 		devinfo->length = NFS4_MAX_UINT64;
+		spin_lock(&mirror->lock);
 		devinfo->read_count = mirror->read_stat.io_stat.ops_completed;
 		devinfo->read_bytes = mirror->read_stat.io_stat.bytes_completed;
 		devinfo->write_count = mirror->write_stat.io_stat.ops_completed;
 		devinfo->write_bytes = mirror->write_stat.io_stat.bytes_completed;
+		spin_unlock(&mirror->lock);
 		devinfo->layout_type = LAYOUT_FLEX_FILES;
 		devinfo->layoutstats_encode = ff_layout_encode_layoutstats;
 		devinfo->layout_private = mirror;
-- 
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