task IO accounting: move all IO statistics in struct task_io_accounting

Simplify the code of include/linux/task_io_accounting.h.

It is also more reasonable to have all the task i/o-related statistics in a
single struct (task_io_accounting).

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index f9cd256..8ebcd85 100644
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -94,14 +94,14 @@
 		stats->hiwater_vm    = mm->hiwater_vm * PAGE_SIZE / KB;
 		mmput(mm);
 	}
-	stats->read_char	= p->ioac.chr.rchar;
-	stats->write_char	= p->ioac.chr.wchar;
-	stats->read_syscalls	= p->ioac.chr.syscr;
-	stats->write_syscalls	= p->ioac.chr.syscw;
+	stats->read_char	= p->ioac.rchar;
+	stats->write_char	= p->ioac.wchar;
+	stats->read_syscalls	= p->ioac.syscr;
+	stats->write_syscalls	= p->ioac.syscw;
 #ifdef CONFIG_TASK_IO_ACCOUNTING
-	stats->read_bytes	= p->ioac.blk.read_bytes;
-	stats->write_bytes	= p->ioac.blk.write_bytes;
-	stats->cancelled_write_bytes = p->ioac.blk.cancelled_write_bytes;
+	stats->read_bytes	= p->ioac.read_bytes;
+	stats->write_bytes	= p->ioac.write_bytes;
+	stats->cancelled_write_bytes = p->ioac.cancelled_write_bytes;
 #else
 	stats->read_bytes	= 0;
 	stats->write_bytes	= 0;