NFS/pNFS: Fix up pNFS write reschedule layering violations and bugs

The flexfiles layout in particular, seems to want to poke around in the
O_DIRECT flags when retransmitting.
This patch sets up an interface to allow it to call back into O_DIRECT
to handle retransmission correctly. It also fixes a potential bug whereby
we could change the behaviour of O_DIRECT if an error is already pending.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 15 insertions, 6 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 4b1d08f56aba..e73693f75dee 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -117,12 +117,6 @@ static inline int put_dreq(struct nfs_direct_req *dreq)
         return atomic_dec_and_test(&dreq->io_count);
 }
 
-void nfs_direct_set_resched_writes(struct nfs_direct_req *dreq)
-{
-        dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
-}
-EXPORT_SYMBOL_GPL(nfs_direct_set_resched_writes);
-
 static void
 nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr)
 {
@@ -839,10 +833,25 @@ static void nfs_write_sync_pgio_error(struct list_head *head)
         }
 }
 
+static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
+{
+        struct nfs_direct_req *dreq = hdr->dreq;
+
+        spin_lock(&dreq->lock);
+        if (dreq->error == 0) {
+                dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+                /* fake unstable write to let common nfs resend pages */
+                hdr->verf.committed = NFS_UNSTABLE;
+                hdr->good_bytes = hdr->args.count;
+        }
+        spin_unlock(&dreq->lock);
+}
+
 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
         .error_cleanup = nfs_write_sync_pgio_error,
         .init_hdr = nfs_direct_pgio_init,
         .completion = nfs_direct_write_completion,
+        .reschedule_io = nfs_direct_write_reschedule_io,
 };