NFSv4.1: turn off pNFS on ds connection failure

If a data server is unavailable, go through MDS.

Mark the deviceid containing the data server as a negative cache entry.
Do not try to connect to any data server on a deviceid marked as a negative
cache entry. Mark any layout that tries to use the marked deviceid as failed.

Inodes with a layout marked as fails will not use the layout for I/O, and will
not perform any more layoutgets.
Inodes without a layout will still do layoutget, but the layout will get
marked immediately.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/nfs/nfs4filelayout.h b/fs/nfs/nfs4filelayout.h
index 23f1e1e2a0f5..ee0c907742b5 100644
--- a/fs/nfs/nfs4filelayout.h
+++ b/fs/nfs/nfs4filelayout.h
@@ -55,10 +55,14 @@ struct nfs4_pnfs_ds {
         atomic_t                ds_count;
 };
 
+/* nfs4_file_layout_dsaddr flags */
+#define NFS4_DEVICE_ID_NEG_ENTRY        0x00000001
+
 struct nfs4_file_layout_dsaddr {
         struct hlist_node               node;
         struct nfs4_deviceid            deviceid;
         atomic_t                        ref;
+        unsigned long                   flags;
         u32                             stripe_count;
         u8                              *stripe_indices;
         u32                             ds_num;