Make taskstats round statistics down to nearest 1k bytes/events

Even with just the interface limited to admin, there really is little to
reason to give byte-per-byte counts for taskstats.  So round it down to
something less intrusive.
Acked-by: NBalbir Singh <bsingharora@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/tsacct.c

@@ -78,6 +78,7 @@ void bacct_add_tsk(struct taskstats *stats, struct task_struct *tsk)
 
 #define KB 1024
 #define MB (1024*KB)
+#define KB_MASK (~(KB-1))
 /*
  * fill in extended accounting fields
  */
@@ -95,14 +96,14 @@ void xacct_add_tsk(struct taskstats *stats, struct task_struct *p)
 		stats->hiwater_vm    = get_mm_hiwater_vm(mm)  * PAGE_SIZE / KB;
 		mmput(mm);
 	}
-	stats->read_char	= p->ioac.rchar;
-	stats->write_char	= p->ioac.wchar;
-	stats->read_syscalls	= p->ioac.syscr;
-	stats->write_syscalls	= p->ioac.syscw;
+	stats->read_char	= p->ioac.rchar & KB_MASK;
+	stats->write_char	= p->ioac.wchar & KB_MASK;
+	stats->read_syscalls	= p->ioac.syscr & KB_MASK;
+	stats->write_syscalls	= p->ioac.syscw & KB_MASK;
 #ifdef CONFIG_TASK_IO_ACCOUNTING
-	stats->read_bytes	= p->ioac.read_bytes;
-	stats->write_bytes	= p->ioac.write_bytes;
-	stats->cancelled_write_bytes = p->ioac.cancelled_write_bytes;
+	stats->read_bytes	= p->ioac.read_bytes & KB_MASK;
+	stats->write_bytes	= p->ioac.write_bytes & KB_MASK;
+	stats->cancelled_write_bytes = p->ioac.cancelled_write_bytes & KB_MASK;
 #else
 	stats->read_bytes	= 0;
 	stats->write_bytes	= 0;