task IO accounting: improve code readability

Put all i/o statistics in struct proc_io_accounting and use inline functions to
initialize and increment statistics, removing a lot of single variable
assignments.

This also reduces the kernel size as following (with CONFIG_TASK_XACCT=y and
CONFIG_TASK_IO_ACCOUNTING=y).

    text    data     bss     dec     hex filename
   11651       0       0   11651    2d83 kernel/exit.o.before
   11619       0       0   11619    2d63 kernel/exit.o.after
   10886     132     136   11154    2b92 kernel/fork.o.before
   10758     132     136   11026    2b12 kernel/fork.o.after

 3082029  807968 4818600 8708597  84e1f5 vmlinux.o.before
 3081869  807968 4818600 8708437  84e155 vmlinux.o.after

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 46 insertions, 10 deletions

diff --git a/include/linux/task_io_accounting_ops.h b/include/linux/task_io_accounting_ops.h
index ff46c6fad79d..e6f958ebe97f 100644
--- a/include/linux/task_io_accounting_ops.h
+++ b/include/linux/task_io_accounting_ops.h
@@ -9,7 +9,7 @@
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 static inline void task_io_account_read(size_t bytes)
 {
-        current->ioac.read_bytes += bytes;
+        current->ioac.blk.read_bytes += bytes;
 }
 
 /*
@@ -18,12 +18,12 @@ static inline void task_io_account_read(size_t bytes)
  */
 static inline unsigned long task_io_get_inblock(const struct task_struct *p)
 {
-        return p->ioac.read_bytes >> 9;
+        return p->ioac.blk.read_bytes >> 9;
 }
 
 static inline void task_io_account_write(size_t bytes)
 {
-        current->ioac.write_bytes += bytes;
+        current->ioac.blk.write_bytes += bytes;
 }
 
 /*
@@ -32,17 +32,25 @@ static inline void task_io_account_write(size_t bytes)
  */
 static inline unsigned long task_io_get_oublock(const struct task_struct *p)
 {
-        return p->ioac.write_bytes >> 9;
+        return p->ioac.blk.write_bytes >> 9;
 }
 
 static inline void task_io_account_cancelled_write(size_t bytes)
 {
-        current->ioac.cancelled_write_bytes += bytes;
+        current->ioac.blk.cancelled_write_bytes += bytes;
 }
 
-static inline void task_io_accounting_init(struct task_struct *tsk)
+static inline void task_io_accounting_init(struct proc_io_accounting *ioac)
 {
-        memset(&tsk->ioac, 0, sizeof(tsk->ioac));
+        memset(ioac, 0, sizeof(*ioac));
+}
+
+static inline void task_blk_io_accounting_add(struct proc_io_accounting *dst,
+                                                struct proc_io_accounting *src)
+{
+        dst->blk.read_bytes += src->blk.read_bytes;
+        dst->blk.write_bytes += src->blk.write_bytes;
+        dst->blk.cancelled_write_bytes += src->blk.cancelled_write_bytes;
 }
 
 #else
@@ -69,9 +77,37 @@ static inline void task_io_account_cancelled_write(size_t bytes)
 {
 }
 
-static inline void task_io_accounting_init(struct task_struct *tsk)
+static inline void task_io_accounting_init(struct proc_io_accounting *ioac)
+{
+}
+
+static inline void task_blk_io_accounting_add(struct proc_io_accounting *dst,
+                                                struct proc_io_accounting *src)
 {
 }
 
-#endif          /* CONFIG_TASK_IO_ACCOUNTING */
-#endif          /* __TASK_IO_ACCOUNTING_OPS_INCLUDED */
+#endif /* CONFIG_TASK_IO_ACCOUNTING */
+
+#ifdef CONFIG_TASK_XACCT
+static inline void task_chr_io_accounting_add(struct proc_io_accounting *dst,
+                                                struct proc_io_accounting *src)
+{
+        dst->chr.rchar += src->chr.rchar;
+        dst->chr.wchar += src->chr.wchar;
+        dst->chr.syscr += src->chr.syscr;
+        dst->chr.syscw += src->chr.syscw;
+}
+#else
+static inline void task_chr_io_accounting_add(struct proc_io_accounting *dst,
+                                                struct proc_io_accounting *src)
+{
+}
+#endif /* CONFIG_TASK_XACCT */
+
+static inline void task_io_accounting_add(struct proc_io_accounting *dst,
+                                                struct proc_io_accounting *src)
+{
+        task_chr_io_accounting_add(dst, src);
+        task_blk_io_accounting_add(dst, src);
+}
+#endif /* __TASK_IO_ACCOUNTING_OPS_INCLUDED */