[PATCH -next] NFS: remove set but not used variable 'mapping'

[YueHaibing]

Fixes gcc '-Wunused-but-set-variable' warning:

fs/nfs/write.c: In function nfs_page_async_flush:
fs/nfs/write.c:609:24: warning: variable mapping set but not used 
[-Wunused-but-set-variable]

It is not use since commit aefb623c422e ("NFS: Fix
writepage(s) error handling to not report errors twice")

Reported-by: Hulk Robot <hul...@huawei.com>
Signed-off-by: YueHaibing <yuehaib...@huawei.com>
---
 fs/nfs/write.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index d193042..85ca495 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -606,7 +606,6 @@ static void nfs_write_error(struct nfs_page *req, int error)
 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
                                struct page *page)
 {
-       struct address_space *mapping;
        struct nfs_page *req;
        int ret = 0;
 
@@ -621,7 +620,6 @@ static int nfs_page_async_flush(struct 
nfs_pageio_descriptor *pgio,
        WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 
        /* If there is a fatal error that covers this write, just exit */
-       mapping = page_file_mapping(page);
        ret = pgio->pg_error;
        if (nfs_error_is_fatal_on_server(ret))
                goto out_launder;
-- 
2.7.4