From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Sun, 28 Jan 2018 14:29:41 +0000 (-0500)
Subject: NFS: Fix a race between mmap() and O_DIRECT
X-Git-Tag: v4.9.82~62
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b79d8854ee0e222c5beb52fc50246ad0b6d9088e;p=thirdparty%2Fkernel%2Fstable.git

NFS: Fix a race between mmap() and O_DIRECT

commit e231c6879cfd44e4fffd384bb6dd7d313249a523 upstream.

When locking the file in order to do O_DIRECT on it, we must unmap
any mmapped ranges on the pagecache so that we can flush out the
dirty data.

Fixes: a5864c999de67 ("NFS: Do not serialise O_DIRECT reads and writes")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/nfs/io.c b/fs/nfs/io.c
index 1fc5d1ce327e2..d18ccc1ce0b57 100644
--- a/fs/nfs/io.c
+++ b/fs/nfs/io.c
@@ -98,7 +98,7 @@ static void nfs_block_buffered(struct nfs_inode *nfsi, struct inode *inode)
 {
 	if (!test_bit(NFS_INO_ODIRECT, &nfsi->flags)) {
 		set_bit(NFS_INO_ODIRECT, &nfsi->flags);
-		nfs_wb_all(inode);
+		nfs_sync_mapping(inode->i_mapping);
 	}
 }