3 files changed, 86 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ad9c460..1208fea 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -82,6 +82,7 @@ struct sched_param {
 #include <linux/resource.h>
 #include <linux/timer.h>
 #include <linux/hrtimer.h>
+#include <linux/task_io_accounting.h>
 
 #include <asm/processor.h>
 
@@ -1013,6 +1014,7 @@ struct task_struct {
 	wait_queue_t *io_wait;
 /* i/o counters(bytes read/written, #syscalls */
 	u64 rchar, wchar, syscr, syscw;
+	struct task_io_accounting ioac;
 #if defined(CONFIG_TASK_XACCT)
 	u64 acct_rss_mem1;	/* accumulated rss usage */
 	u64 acct_vm_mem1;	/* accumulated virtual memory usage */
diff --git a/include/linux/task_io_accounting.h b/include/linux/task_io_accounting.h
new file mode 100644
index 0000000..44d00e9
--- /dev/null
+++ b/include/linux/task_io_accounting.h
@@ -0,0 +1,37 @@
+/*
+ * task_io_accounting: a structure which is used for recording a single task's
+ * IO statistics.
+ *
+ * Don't include this header file directly - it is designed to be dragged in via
+ * sched.h.
+ *
+ * Blame akpm@osdl.org for all this.
+ */
+
+#ifdef CONFIG_TASK_IO_ACCOUNTING
+struct task_io_accounting {
+	/*
+	 * The number of bytes which this task has caused to be read from
+	 * storage.
+	 */
+	u64 read_bytes;
+
+	/*
+	 * The number of bytes which this task has caused, or shall cause to be
+	 * written to disk.
+	 */
+	u64 write_bytes;
+
+	/*
+	 * A task can cause "negative" IO too.  If this task truncates some
+	 * dirty pagecache, some IO which another task has been accounted for
+	 * (in its write_bytes) will not be happening.  We _could_ just
+	 * subtract that from the truncating task's write_bytes, but there is
+	 * information loss in doing that.
+	 */
+	u64 cancelled_write_bytes;
+};
+#else
+struct task_io_accounting {
+};
+#endif
diff --git a/include/linux/task_io_accounting_ops.h b/include/linux/task_io_accounting_ops.h
new file mode 100644
index 0000000..df2a319
--- /dev/null
+++ b/include/linux/task_io_accounting_ops.h
@@ -0,0 +1,47 @@
+/*
+ * Task I/O accounting operations
+ */
+#ifndef __TASK_IO_ACCOUNTING_OPS_INCLUDED
+#define __TASK_IO_ACCOUNTING_OPS_INCLUDED
+
+#ifdef CONFIG_TASK_IO_ACCOUNTING
+static inline void task_io_account_read(size_t bytes)
+{
+	current->ioac.read_bytes += bytes;
+}
+
+static inline void task_io_account_write(size_t bytes)
+{
+	current->ioac.write_bytes += bytes;
+}
+
+static inline void task_io_account_cancelled_write(size_t bytes)
+{
+	current->ioac.cancelled_write_bytes += bytes;
+}
+
+static inline void task_io_accounting_init(struct task_struct *tsk)
+{
+	memset(&tsk->ioac, 0, sizeof(tsk->ioac));
+}
+
+#else
+
+static inline void task_io_account_read(size_t bytes)
+{
+}
+
+static inline void task_io_account_write(size_t bytes)
+{
+}
+
+static inline void task_io_account_cancelled_write(size_t bytes)
+{
+}
+
+static inline void task_io_accounting_init(struct task_struct *tsk)
+{
+}
+
+#endif		/* CONFIG_TASK_IO_ACCOUNTING */
+#endif		/* __TASK_IO_ACCOUNTING_OPS_INCLUDED */