[PATCH 5/7] NFS: Add READ_PLUS hole segment decoding

[schumaker.anna@gmail.com]

From: Anna Schumaker <Anna.Schumaker@Netapp.com>

We keep things simple for now by only decoding a single hole or data
segment returned by the server, even if they returned more to us.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
 fs/nfs/nfs42xdr.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs42xdr.c b/fs/nfs/nfs42xdr.c
index bf118ecabe2c..3407a3cf2e13 100644
--- a/fs/nfs/nfs42xdr.c
+++ b/fs/nfs/nfs42xdr.c
@@ -47,7 +47,7 @@
 #define decode_deallocate_maxsz		(op_decode_hdr_maxsz)
 #define encode_read_plus_maxsz		(op_encode_hdr_maxsz + \
 					 encode_stateid_maxsz + 3)
-#define NFS42_READ_PLUS_SEGMENT_SIZE	(1 /* data_content4 */ + \
+#define NFS42_READ_PLUS_SEGMENT_SIZE	(2 /* data_content4 */ + \
 					 2 /* data_info4.di_offset */ + \
 					 2 /* data_info4.di_length */)
 #define decode_read_plus_maxsz		(op_decode_hdr_maxsz + \
@@ -771,6 +771,31 @@ static uint32_t decode_read_plus_data(struct xdr_stream *xdr, struct nfs_pgio_re
 	return count;
 }
 
+static uint32_t decode_read_plus_hole(struct xdr_stream *xdr, struct nfs_pgio_res *res,
+				      uint32_t *eof)
+{
+	__be32 *p;
+	uint64_t offset, length;
+	size_t recvd;
+
+	p = xdr_inline_decode(xdr, 8 + 8);
+	if (unlikely(!p))
+		return -EIO;
+
+	p = xdr_decode_hyper(p, &offset);
+	p = xdr_decode_hyper(p, &length);
+	if (length == 0)
+		return 0;
+
+	recvd = xdr_expand_hole(xdr, 0, length);
+	if (recvd < length) {
+		*eof = 0;
+		length = recvd;
+	}
+
+	return length;
+}
+
 static int decode_read_plus(struct xdr_stream *xdr, struct nfs_pgio_res *res)
 {
 	__be32 *p;
@@ -798,7 +823,10 @@ static int decode_read_plus(struct xdr_stream *xdr, struct nfs_pgio_res *res)
 	if (type == NFS4_CONTENT_DATA)
 		count = decode_read_plus_data(xdr, res, &eof);
 	else
-		return -EINVAL;
+		count = decode_read_plus_hole(xdr, res, &eof);
+
+	if (segments > 1)
+		eof = 0;
 
 	res->eof = eof;
 	res->count = count;
-- 
2.24.1