NFS: Read unlock folio on nfs_page_create_from_folio() error

The netfs conversion lost a folio_unlock() for the case where
nfs_page_create_from_folio() returns an error (usually -ENOMEM).  Restore
it.
Reported-by: David Jeffery <djeffery@redhat.com>
Cc: <stable@vger.kernel.org> # 6.4+
Fixes: 000dbe0b ("NFS: Convert buffered read paths to use netfs when fscache is enabled")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Acked-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/read.c

@@ -305,6 +305,8 @@ int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio,
 	new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len);
 	if (IS_ERR(new)) {
 		error = PTR_ERR(new);
+		if (nfs_netfs_folio_unlock(folio))
+			folio_unlock(folio);
 		goto out;
 	}