pnfs: encode_layoutreturn

Add a layout driver method to encode the layout type specific
opaque part of layout return in-line in the xdr stream.

Currently the pnfs-objects layout driver uses it to encode i/o error
information on LAYOUTRETURN.

Signed-off-by: Andy Adamson <andros@netapp.com>
[fixup layout header pointer for encode_layoutreturn]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

2 files changed, 11 insertions, 2 deletions

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index f24212064356..d464badc0067 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1920,8 +1920,13 @@ encode_layoutreturn(struct xdr_stream *xdr,
         spin_lock(&args->inode->i_lock);
         xdr_encode_opaque_fixed(p, &args->stateid.data, NFS4_STATEID_SIZE);
         spin_unlock(&args->inode->i_lock);
-        p = reserve_space(xdr, 4);
-        *p = cpu_to_be32(0);
+        if (NFS_SERVER(args->inode)->pnfs_curr_ld->encode_layoutreturn) {
+                NFS_SERVER(args->inode)->pnfs_curr_ld->encode_layoutreturn(
+                        NFS_I(args->inode)->layout, xdr, args);
+        } else {
+                p = reserve_space(xdr, 4);
+                *p = cpu_to_be32(0);
+        }
         hdr->nops++;
         hdr->replen += decode_layoutreturn_maxsz;
 }
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index af3967a893a1..1b6b207a8806 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -104,6 +104,10 @@ struct pnfs_layoutdriver_type {
         enum pnfs_try_status (*write_pagelist) (struct nfs_write_data *nfs_data, int how);
 
         void (*free_deviceid_node) (struct nfs4_deviceid_node *);
+
+        void (*encode_layoutreturn) (struct pnfs_layout_hdr *layoutid,
+                                     struct xdr_stream *xdr,
+                                     const struct nfs4_layoutreturn_args *args);
 };
 
 struct pnfs_layout_hdr {