nfsd: Add ALLOCATE support

The ALLOCATE operation is used to preallocate space in a file.  I can do
this by using vfs_fallocate() to do the actual preallocation.

ALLOCATE only returns a status indicator, so we don't need to write a
special encode() function.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index eeea7a9..a60cff8 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1514,6 +1514,23 @@
 }
 
 static __be32
+nfsd4_decode_fallocate(struct nfsd4_compoundargs *argp,
+		       struct nfsd4_fallocate *fallocate)
+{
+	DECODE_HEAD;
+
+	status = nfsd4_decode_stateid(argp, &fallocate->falloc_stateid);
+	if (status)
+		return status;
+
+	READ_BUF(16);
+	p = xdr_decode_hyper(p, &fallocate->falloc_offset);
+	xdr_decode_hyper(p, &fallocate->falloc_length);
+
+	DECODE_TAIL;
+}
+
+static __be32
 nfsd4_decode_seek(struct nfsd4_compoundargs *argp, struct nfsd4_seek *seek)
 {
 	DECODE_HEAD;
@@ -1604,7 +1621,7 @@
 	[OP_RECLAIM_COMPLETE]	= (nfsd4_dec)nfsd4_decode_reclaim_complete,
 
 	/* new operations for NFSv4.2 */
-	[OP_ALLOCATE]		= (nfsd4_dec)nfsd4_decode_notsupp,
+	[OP_ALLOCATE]		= (nfsd4_dec)nfsd4_decode_fallocate,
 	[OP_COPY]		= (nfsd4_dec)nfsd4_decode_notsupp,
 	[OP_COPY_NOTIFY]	= (nfsd4_dec)nfsd4_decode_notsupp,
 	[OP_DEALLOCATE]		= (nfsd4_dec)nfsd4_decode_notsupp,