nfsd: Add DEALLOCATE support

DEALLOCATE only returns a status value, meaning we can use the noop()
xdr encoder to reply to the client.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4proc.c

@@ -33,6 +33,7 @@
  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include <linux/file.h>
+#include <linux/falloc.h>
 #include <linux/slab.h>
 
 #include "idmap.h"
@@ -1043,6 +1044,14 @@ nfsd4_allocate(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	return nfsd4_fallocate(rqstp, cstate, fallocate, 0);
 }
 
+static __be32
+nfsd4_deallocate(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
+		 struct nfsd4_fallocate *fallocate)
+{
+	return nfsd4_fallocate(rqstp, cstate, fallocate,
+			       FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE);
+}
+
 static __be32
 nfsd4_seek(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		struct nfsd4_seek *seek)
@@ -1965,6 +1974,12 @@ static struct nfsd4_operation nfsd4_ops[] = {
 		.op_name = "OP_ALLOCATE",
 		.op_rsize_bop = (nfsd4op_rsize)nfsd4_write_rsize,
 	},
+	[OP_DEALLOCATE] = {
+		.op_func = (nfsd4op_func)nfsd4_deallocate,
+		.op_flags = OP_MODIFIES_SOMETHING | OP_CACHEME,
+		.op_name = "OP_DEALLOCATE",
+		.op_rsize_bop = (nfsd4op_rsize)nfsd4_write_rsize,
+	},
 	[OP_SEEK] = {
 		.op_func = (nfsd4op_func)nfsd4_seek,
 		.op_name = "OP_SEEK",