ANDROID: taskstats: track fsync syscalls

This adds a counter to the taskstats extended accounting fields, which
tracks the number of times fsync is called, and then plumbs it through
to the uid_sys_stats driver.

Bug: 120442023
Change-Id: I6c138de5b2332eea70f57e098134d1d141247b3f
Signed-off-by: Jin Qian <jinqian@google.com>
[AmitP: Refactored changes to align with changes from upstream commit
        9a07000400 ("sched/headers: Move CONFIG_TASK_XACCT bits from <linux/sched.h> to <linux/sched/xacct.h>")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
[tkjos: Needed for storaged fsync accounting ("storaged --uid" and
        "storaged --task").]
[astrachan: This is modifying a userspace interface and should probably
            be reworked]
Signed-off-by: Alistair Strachan <astrachan@google.com>

drivers/misc/Kconfig

@@ -515,7 +515,7 @@ config MISC_RTSX
 
 config UID_SYS_STATS
 	bool "Per-UID statistics"
-	depends on PROFILING && TASK_IO_ACCOUNTING
+	depends on PROFILING && TASK_XACCT && TASK_IO_ACCOUNTING
 	help
 	  Per UID based cpu time statistics exported to /proc/uid_cputime
 	  Per UID based io statistics exported to /proc/uid_io

drivers/misc/uid_sys_stats.c

@@ -249,6 +249,7 @@ static void add_uid_tasks_io_stats(struct uid_entry *uid_entry,
 	task_io_slot->write_bytes += compute_write_bytes(task);
 	task_io_slot->rchar += task->ioac.rchar;
 	task_io_slot->wchar += task->ioac.wchar;
+	task_io_slot->fsync += task->ioac.syscfs;
 }
 
 static void compute_io_uid_tasks(struct uid_entry *uid_entry)
@@ -452,6 +453,7 @@ static void add_uid_io_stats(struct uid_entry *uid_entry,
 	io_slot->write_bytes += compute_write_bytes(task);
 	io_slot->rchar += task->ioac.rchar;
 	io_slot->wchar += task->ioac.wchar;
+	io_slot->fsync += task->ioac.syscfs;
 
 	add_uid_tasks_io_stats(uid_entry, task, slot);
 }

fs/sync.c

@@ -9,7 +9,7 @@
 #include <linux/slab.h>
 #include <linux/export.h>
 #include <linux/namei.h>
-#include <linux/sched.h>
+#include <linux/sched/xacct.h>
 #include <linux/writeback.h>
 #include <linux/syscalls.h>
 #include <linux/linkage.h>
@@ -220,6 +220,7 @@ static int do_fsync(unsigned int fd, int datasync)
 	if (f.file) {
 		ret = vfs_fsync(f.file, datasync);
 		fdput(f);
+		inc_syscfs(current);
 	}
 	return ret;
 }

include/linux/sched/xacct.h

@@ -28,6 +28,11 @@ static inline void inc_syscw(struct task_struct *tsk)
 {
 	tsk->ioac.syscw++;
 }
+
+static inline void inc_syscfs(struct task_struct *tsk)
+{
+	tsk->ioac.syscfs++;
+}
 #else
 static inline void add_rchar(struct task_struct *tsk, ssize_t amt)
 {
@@ -44,6 +49,10 @@ static inline void inc_syscr(struct task_struct *tsk)
 static inline void inc_syscw(struct task_struct *tsk)
 {
 }
+
+static inline void inc_syscfs(struct task_struct *tsk)
+{
+}
 #endif
 
 #endif /* _LINUX_SCHED_XACCT_H */

include/linux/task_io_accounting.h

@@ -19,6 +19,8 @@ struct task_io_accounting {
 	u64 syscr;
 	/* # of write syscalls */
 	u64 syscw;
+	/* # of fsync syscalls */
+	u64 syscfs;
 #endif /* CONFIG_TASK_XACCT */
 
 #ifdef CONFIG_TASK_IO_ACCOUNTING

include/linux/task_io_accounting_ops.h

@@ -97,6 +97,7 @@ static inline void task_chr_io_accounting_add(struct task_io_accounting *dst,
 	dst->wchar += src->wchar;
 	dst->syscr += src->syscr;
 	dst->syscw += src->syscw;
+	dst->syscfs += src->syscfs;
 }
 #else
 static inline void task_chr_io_accounting_add(struct task_io_accounting *dst,