NFS: account direct-io into task io accounting

Account NFS direct-io reads and writes into Task I/O Accounting.
Do it before complition to handle aio.

NFS have unusual direct-io implementation,
thus accounting in generic code does not work.
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/direct.c

@@ -45,6 +45,7 @@
 #include <linux/pagemap.h>
 #include <linux/kref.h>
 #include <linux/slab.h>
+#include <linux/task_io_accounting_ops.h>
 
 #include <linux/nfs_fs.h>
 #include <linux/nfs_page.h>
@@ -937,6 +938,8 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
 	if (retval)
 		goto out;
 
+	task_io_account_read(count);
+
 	retval = nfs_direct_read(iocb, iov, nr_segs, pos);
 	if (retval > 0)
 		iocb->ki_pos = pos + retval;
@@ -998,6 +1001,8 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 	if (retval)
 		goto out;
 
+	task_io_account_write(count);
+
 	retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
 
 	if (retval > 0)