From: Chengguang Xu <cgxu519@icloud.com>
Date: Tue, 30 Jan 2018 10:02:30 +0800
Subject: ceph: improving efficiency of syncfs
Git-commit: 16515a6d54183349b858b9c05e483afc55fa7948
Patch-mainline: v4.16-rc1
References: FATE#324714

write_inode() could be called variety of reasons, in the case of syncfs(2)
there is no need to wait for flush getting completed in write_inode(),
->sync_fs is for guaranteeing flush completion for all inodes at that point.

Signed-off-by: Chengguang Xu <cgxu519@icloud.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 fs/ceph/caps.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2206,7 +2206,7 @@ int ceph_write_inode(struct inode *inode
 	u64 flush_tid;
 	int err = 0;
 	int dirty;
-	int wait = wbc->sync_mode == WB_SYNC_ALL;
+	int wait = (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync);
 
 	dout("write_inode %p wait=%d\n", inode, wait);
 	if (wait) {