cat: /tmp/jfs/.accesslog: Bad file descriptor on graceful upgrade

[zhoucheng361]

What happened:
in terminal 1: mount juicefs
root@bench-01:~/juicefs# ./juicefs mount -d sqlite3://test.db /tmp/jfs

in terminal 2: cat accesslog
root@bench-01:~# cat /tmp/jfs/.accesslog

in terminal 1: remount juicefs
root@bench-01:~/juicefs# ./juicefs mount -d sqlite3://test.db /tmp/jfs

in terminal 2: exit with "cat: /tmp/jfs/.accesslog: Bad file descriptor"

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?

Environment:

• JuiceFS version (use juicefs --version) or Hadoop Java SDK version:
• Cloud provider or hardware configuration running JuiceFS:
• OS (e.g cat /etc/os-release):
• Kernel (e.g. uname -a):
• Object storage (cloud provider and region, or self maintained):
• Metadata engine info (version, cloud provider managed or self maintained):
• Network connectivity (JuiceFS to metadata engine, JuiceFS to object storage):
• Others: