很长一段时间以来，在我的笔记本电脑上，git 或 megasync 都无法检测到文件的变化。它们看到新文件，但看不到更改的文件。文件系统的安装方式如下：
/dev/mapper/vgroot-lvroot on / type btrfs (rw,relatime,ssd,space_cache,subvolid=523,subvol=/@root)
/tmp$ mkdir test; cd test
/tmp/test$ git init
Initialized empty Git repository in /tmp/test/.git/
/tmp/test$ touch a
/tmp/test$ git stage a
/tmp/test$ git commit -a -m 'a'
[master (root-commit) ea2464b] a
1 file changed, 0 insertions(+), 0 deletions(-)
create mode 100644 a
/tmp/test$ stat a
File: 'a'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 17h/23d Inode: 12931371 Links: 1
Access: (0644/-rw-r--r--) Uid: (SOMETHING) Gid: (SOMETHING)
Access: 2016-11-07 19:55:44.945089596 +0800
Modify: 2016-11-07 19:55:44.945089596 +0800
Change: 2016-11-07 19:55:44.945089596 +0800
Birth: -
/tmp/test$ vim a
/tmp/test$ stat a
File: 'a'
Size: 4 Blocks: 8 IO Block: 4096 regular file
Device: 17h/23d Inode: 12931371 Links: 1
Access: (0644/-rw-r--r--) Uid: (SOMETHING) Gid: (SOMETHING)
Access: 2016-11-07 19:56:04.804211299 +0800
Modify: 2016-11-07 19:56:06.980224918 +0800
Change: 2016-11-07 19:56:06.985224949 +0800
Birth: -
/tmp/test$ git status
On branch master
nothing to commit, working tree clean