NFS: Fix memory leaks in nfs_pageio_stop_mirroring()

stable inclusion
from linux-4.19.118
commit b38f7532eb1549a43bcc8dfd6c197adccfa84a00

--------------------------------

[ Upstream commit 862f35c9 ]

If we just set the mirror count to 1 without first clearing out
the mirrors, we can leak queued up requests.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

fs/nfs/pagelist.c

@@ -865,15 +865,6 @@ static void nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 	pgio->pg_mirror_count = mirror_count;
 }
 
-/*
- * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
- */
-void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
-{
-	pgio->pg_mirror_count = 1;
-	pgio->pg_mirror_idx = 0;
-}
-
 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 {
 	pgio->pg_mirror_count = 1;
@@ -1302,6 +1293,14 @@ void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
 	}
 }
 
+/*
+ * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
+ */
+void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
+{
+	nfs_pageio_complete(pgio);
+}
+
 int __init nfs_init_nfspagecache(void)
 {
 	nfs_page_cachep = kmem_cache_create("nfs_page",