[PATCH] f2fs: avoid writing inode redundantly when creating a file

[Jin Xu <jinuxstyle@gmail.com>]

From: Jin Xu <jinuxstyle@gmail.com>

In f2fs_write_inode, updating inode after f2fs_balance_fs is not
a optimized way in the case that f2fs_gc is performed ahead. The
inode page will be unnecessarily written out twice, one of which
is in f2fs_gc->...->sync_node_pages and the other is in
update_inode_page.

Let's update the inode page in prior to f2fs_balance_fs to avoid
this.

To reproduce it,
$ touch file (before this step, should make the device need f2fs_gc)
$ sync (or wait the bdi to write dirty inode)

Signed-off-by: Jin Xu <jinuxstyle@gmail.com>
---
 fs/f2fs/inode.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index d42b85b..675b84a 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -222,9 +222,6 @@ int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc)
 	if (!is_inode_flag_set(F2FS_I(inode), FI_DIRTY_INODE))
 		return 0;
 
-	if (wbc)
-		f2fs_balance_fs(sbi);
-
 	/*
 	 * We need to lock here to prevent from producing dirty node pages
 	 * during the urgent cleaning time when runing out of free sections.
@@ -232,6 +229,10 @@ int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc)
 	ilock = mutex_lock_op(sbi);
 	ret = update_inode_page(inode);
 	mutex_unlock_op(sbi, ilock);
+
+	if (wbc)
+		f2fs_balance_fs(sbi);
+
 	return ret;
 }
 
-- 
1.7.9.5