NFS: Fix a potential data corruption

commit 88975a55969e11f26fe3846bf4fbf8e7dc8cbbd4 upstream.

We must ensure that the subrequests are joined back into the head before
we can retransmit a request. If the head was not on the commit lists,
because the server wrote it synchronously, we still need to add it back
to the retransmission list.
Add a call that mirrors the effect of nfs_cancel_remove_inode() for
O_DIRECT.

Fixes: ed5d588fe47f ("NFS: Try to join page groups before an O_DIRECT retransmission")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index cf34d0c..3bb530d 100644 (file)
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -474,13 +474,31 @@ out:
        return result;
 }
 
+static void nfs_direct_add_page_head(struct list_head *list,
+                                    struct nfs_page *req)
+{
+       struct nfs_page *head = req->wb_head;
+
+       if (!list_empty(&head->wb_list) || !nfs_lock_request(head))
+               return;
+       if (!list_empty(&head->wb_list)) {
+               nfs_unlock_request(head);
+               return;
+       }
+       list_add(&head->wb_list, list);
+       kref_get(&head->wb_kref);
+       kref_get(&head->wb_kref);
+}
+
 static void nfs_direct_join_group(struct list_head *list, struct inode *inode)
 {
        struct nfs_page *req, *subreq;
 
        list_for_each_entry(req, list, wb_list) {
-               if (req->wb_head != req)
+               if (req->wb_head != req) {
+                       nfs_direct_add_page_head(&req->wb_list, req);
                        continue;
+               }
                subreq = req->wb_this_page;
                if (subreq == req)
                        continue;