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, 3 insertions, 1 deletions

diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index a922e75af42e..0040a5ee6208 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -214,7 +214,9 @@ filelayout_read_pagelist(struct nfs_read_data *data)
         idx = nfs4_fl_calc_ds_index(lseg, j);
         ds = nfs4_fl_prepare_ds(lseg, idx);
         if (!ds) {
-                printk(KERN_ERR "%s: prepare_ds failed, use MDS\n", __func__);
+                /* Either layout fh index faulty, or ds connect failed */
+                set_bit(lo_fail_bit(IOMODE_RW), &lseg->pls_layout->plh_flags);
+                set_bit(lo_fail_bit(IOMODE_READ), &lseg->pls_layout->plh_flags);
                 return PNFS_NOT_ATTEMPTED;
         }
         dprintk("%s USE DS:ip %x %hu\n", __func__,