linux-kernel - [PATCH 4.19 02/48] NFSv42: Fix pagecache invalidation after COPY/CLONE

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Date:   Mon,  6 Dec 2021 15:56:19 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Benjamin Coddington <bcodding@...hat.com>,
        Trond Myklebust <trond.myklebust@...merspace.com>
Subject: [PATCH 4.19 02/48] NFSv42: Fix pagecache invalidation after COPY/CLONE

From: Benjamin Coddington <bcodding@...hat.com>

commit 3f015d89a47cd8855cd92f71fff770095bd885a1 upstream.

The mechanism in use to allow the client to see the results of COPY/CLONE
is to drop those pages from the pagecache.  This forces the client to read
those pages once more from the server.  However, truncate_pagecache_range()
zeros out partial pages instead of dropping them.  Let us instead use
invalidate_inode_pages2_range() with full-page offsets to ensure the client
properly sees the results of COPY/CLONE operations.

Cc: <stable@...r.kernel.org> # v4.7+
Fixes: 2e72448b07dc ("NFS: Add COPY nfs operation")
Signed-off-by: Benjamin Coddington <bcodding@...hat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@...merspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/nfs/nfs42proc.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -295,8 +295,9 @@ static ssize_t _nfs42_proc_copy(struct f
 			goto out;
 	}
 
-	truncate_pagecache_range(dst_inode, pos_dst,
-				 pos_dst + res->write_res.count);
+	WARN_ON_ONCE(invalidate_inode_pages2_range(dst_inode->i_mapping,
+					pos_dst >> PAGE_SHIFT,
+					(pos_dst + res->write_res.count - 1) >> PAGE_SHIFT));
 
 	status = res->write_res.count;
 out: