[PATCH v2 22/29] pnfs: encode_layoutreturn

[Benny Halevy <bhalevy@panasas.com>]

From: Andy Adamson <andros@netapp.com>

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>
---
 fs/nfs/nfs4xdr.c |    9 +++++++--
 fs/nfs/pnfs.h    |    4 ++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 34fc994..75ad9e1 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1921,8 +1921,13 @@ encode_layoutreturn(struct xdr_stream *xdr,
 	spin_lock(&args->inode->i_lock);
 	xdr_encode_opaque_fixed(p, &NFS_I(args->inode)->layout->plh_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 a54e715..798861c 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -106,6 +106,10 @@ struct pnfs_layoutdriver_type {
 
 	/* device notification methods */
 	void (*delete_deviceid)(struct nfs4_deviceid *);
+
+	void (*encode_layoutreturn) (struct pnfs_layout_hdr *layoutid,
+				     struct xdr_stream *xdr,
+				     const struct nfs4_layoutreturn_args *args);
 };
 
 struct pnfs_layout_hdr {
-- 
1.7.3.4