Cannot umount a volume

[myc724]

I’m trying to build a flow on the top of JuiceFS and Redis. Everything seems work but I cannot umount volumes at the end. Also, the mountpoints seems created as root while I do not have root access to these machines. Follow lines summarize my flow. Does anyone know what’s the issue? Thanks!

I started a rediss on machine1 for object storage service @ port 6000.
I started a rediss on machine2 for metadata service @ port 7000.

On machine3, I created a volume as follow
juicefs format --storage=redis --bucket=redis://machine1:6000 redis://machine2:7000/0 test

On machine4 and machine5, I mounted this volume to each machine's local /tmp as follow
juicefs mount -d redis://machine2:7000/0 /tmp/jfs

Afterward, I can create/write/read files either machine4 or machine5 and JuiceFS synchronized each machine’s local /tmp/jfs perfectly. However, I cannot umount the mountpoint (from either machine4 or machine5). I used this command.
juicefs --debug umount -f /tmp/jfs

Also, I realized the mountpoint were created as root, while I do not have root access to these machines.
drwxrwxrwx 4 root root 4096 Mar 5 18:17 jfs

After I sigkill the “juicefs mount …” processes, mountpioint turned into this.
d????????? ? ? ? ? ? jfs

“ls /tmp/jfs” complained as follow.
ls: cannot access /tmp/jfs: Transport endpoint is not connected

Does anyone know what part were wrong? Thanks!

[chnliyong]

I tried mount (the juicefs main branch code: a7e2431) with user ubuntu in my Ubuntu 20.04 virtual machine:

$ ./juicefs mount -d redis://:[email protected]/2 /tmp/jfs
2021/03/08 11:35:56.769313 juicefs[9891] <INFO>: Meta address: redis://:[email protected]/2
2021/03/08 11:35:56.773734 juicefs[9891] <WARNING>: AOF is not enabled, you may lose data if Redis is not shutdown properly.
2021/03/08 11:35:56.775340 juicefs[9891] <INFO>: Data use s3://juicefs-dev/dev/
2021/03/08 11:35:56.775496 juicefs[9891] <INFO>: Cache: /var/jfsCache/c21e50f9-2997-4e6a-bbd8-149ca962d338 capacity: 1024 MB
2021/03/08 11:35:56.775640 juicefs[9891] <WARNING>: statfs /var/jfsCache/c21e50f9-2997-4e6a-bbd8-149ca962d338/: permission denied
2021/03/08 11:35:56.776179 juicefs[9891] <WARNING>: statfs /var/jfsCache/c21e50f9-2997-4e6a-bbd8-149ca962d338/: permission denied
2021/03/08 11:35:56.928953 juicefs[9891] <INFO>: OK, dev is ready at /tmp/jfs

$ df -h | grep JuiceFS
JuiceFS:dev     1.0P   64K  1.0P   1% /tmp/jfs

$ ls -ld /tmp/jfs
drwxrwxrwx 1 root root 4096 Mar  3 09:09 /tmp/jfs

$ ./juicefs umount /tmp/jfs
<umount success, no output>

$ ls -ld /tmp/jfs
drwxrwxr-x 2 ubuntu ubuntu 4096 Mar  8 11:32 /tmp/jfs

$ df -h | grep JuiceFS
<no output>

I cannot reproduce your problem, can you provide more information like operation system ( cat /etc/os-release; uname -a ), JuiceFS version (./juicefs -V) etc. ?

[chnliyong]

I created an CentOS 7.2 public cloud virtual machine and reproduced your problem.
In short, the umount is too old to support unmount the fuse filesystem, and we can use fusermount -u /tmp/jfs to unmount the fuse filesystem.

It seems the umount(in package util-linux) is not support fuse mount. I read the util-linux source code commit history, the first time it add support for fuse mounts is this commit, which happened on the day 2018-11-30 . On the server I reproduced this problem, the version is 2.23.2 as show below:

$ rpm -qif /bin/umount
Name        : util-linux
Version     : 2.23.2
Release     : 33.el7_3.2
Architecture: x86_64
Install Date: Thu 17 Aug 2017 07:45:12 AM CST
Group       : System Environment/Base
Size        : 8192921
License     : GPLv2 and GPLv2+ and LGPLv2+ and BSD with advertising and Public Domain
Signature   : RSA/SHA256, Thu 13 Apr 2017 09:40:56 AM CST, Key ID 24c6a8a7f4a80eb5
Source RPM  : util-linux-2.23.2-33.el7_3.2.src.rpm
Build Date  : Thu 13 Apr 2017 04:43:54 AM CST
Build Host  : c1bm.rdu2.centos.org
Relocations : (not relocatable)
Packager    : CentOS BuildSystem <http://bugs.centos.org>
Vendor      : CentOS
URL         : http://en.wikipedia.org/wiki/Util-linux
Summary     : A collection of basic system utilities
Description :
The util-linux package contains a large variety of low-level system
utilities that are necessary for a Linux system to function. Among
others, Util-linux contains the fdisk configuration tool and the login
program.

The release date of this version is 2013-07-31 from this commit, obviously not support unmount the fuse filesystem.

[chnliyong]

If you mount JuiceFS with regular user, please use --cache-dir to change the default cache directory (/var/jfsCache), otherwise it will continuously complain the no permission warning log.

[chnliyong]

Will fix in this PR #242

[myc724]

"fusermount -u " works. Thanks a lot!
Look for PR #242.

[myc724]

Thanks a lot for the quick fix!