From d2cdb4e1ce3df4e28b0e51807455ddf424ff2e71 Mon Sep 17 00:00:00 2001
From: Paul Reioux <reioux@gmail.com>
Date: Sun, 29 Mar 2015 14:52:41 -0400
Subject: Dynamic Fsync Control

---
 fs/sync.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

(limited to 'fs/sync.c')

diff --git a/fs/sync.c b/fs/sync.c
index 905f3f6b3..686996e50 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -17,6 +17,11 @@
 #include <linux/backing-dev.h>
 #include "internal.h"
 
+#ifdef CONFIG_DYNAMIC_FSYNC
+extern bool early_suspend_active;
+extern bool dyn_fsync_active;
+#endif
+
 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
 			SYNC_FILE_RANGE_WAIT_AFTER)
 
@@ -89,6 +94,17 @@ static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
 	filemap_fdatawait(bdev->bd_inode->i_mapping);
 }
 
+#ifndef CONFIG_DYNAMIC_FSYNC
+static
+#endif
+void sync_filesystems(int wait)
+{
+	iterate_supers(sync_fs_one_sb, &wait);
+}
+#ifdef CONFIG_DYNAMIC_FSYNC
+EXPORT_SYMBOL_GPL(sync_filesystems);
+#endif
+
 /*
  * Sync everything. We start by waking flusher threads so that most of
  * writeback runs on all devices in parallel. Then we sync all inodes reliably
@@ -193,7 +209,15 @@ EXPORT_SYMBOL(vfs_fsync_range);
  */
 int vfs_fsync(struct file *file, int datasync)
 {
+#ifdef CONFIG_DYNAMIC_FSYNC
+	if (likely(dyn_fsync_active && !early_suspend_active))
+		return 0;
+	else {
+#endif
 	return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
+#ifdef CONFIG_DYNAMIC_FSYNC
+	}
+#endif	
 }
 EXPORT_SYMBOL(vfs_fsync);
 
@@ -211,11 +235,21 @@ static int do_fsync(unsigned int fd, int datasync)
 
 SYSCALL_DEFINE1(fsync, unsigned int, fd)
 {
+#ifdef CONFIG_DYNAMIC_FSYNC
+	if (likely(dyn_fsync_active && !early_suspend_active))
+		return 0;
+	else
+#endif
 	return do_fsync(fd, 0);
 }
 
 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
 {
+#if 0
+	if (likely(dyn_fsync_active && !early_suspend_active))
+		return 0;
+	else
+#endif
 	return do_fsync(fd, 1);
 }
 
@@ -286,6 +320,12 @@ EXPORT_SYMBOL(generic_write_sync);
 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
 				unsigned int, flags)
 {
+#ifdef CONFIG_DYNAMIC_FSYNC
+if (likely(dyn_fsync_active && !early_suspend_active))
+return 0;
+else {
+#endif
+
 	int ret;
 	struct fd f;
 	struct address_space *mapping;
@@ -364,6 +404,9 @@ out_put:
 	fdput(f);
 out:
 	return ret;
+#ifdef CONFIG_DYNAMIC_FSYNC
+	}
+#endif	
 }
 
 /* It would be nice if people remember that not all the world's an i386
@@ -371,5 +414,10 @@ out:
 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
 				 loff_t, offset, loff_t, nbytes)
 {
+#ifdef CONFIG_DYNAMIC_FSYNC
+	if (likely(dyn_fsync_active && !early_suspend_active))
+		return 0;
+	else
+#endif
 	return sys_sync_file_range(fd, offset, nbytes, flags);
 }
-- 
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