fuse mount with root failed about fuse

[stapelberg]

Does this only happen when you’re running as root, or also as your user?

If it happens only as root, can you try sudo chown root.root /home/wangyang5/polefs/mnt and see if that helps?

If this is blocking you, a workaround would be to add a check for syscall.EINVAL and return errFallback in

fuse/mount_linux.go

Line 160 in 2f65426

if err == syscall.EPERM {

[kungf]

only root user has this problem

[kungf]

i find in man 2 mount

EINVAL source had an invalid superblock.

source is selfdefined fsname "polefs-wy3", i am not sure how mount get the superblock of source?
why fusermount is ok?

[stapelberg]

i find in man 2 mount

EINVAL source had an invalid superblock.

I don’t think this applies. The mount manpage was written for traditional file systems, not FUSE.

I just tried to reproduce the issue, but can’t:

From your log:

432551 mount("polefs-wy3", "/home/wangyang5/polefs/mnt", "fuse", MS_NODEV, "fd=12,rootmode=40000,user_id=0,group_id=0,default_permissions,subtype=polefs,allow_other") = -1 EINVAL (Invalid argument)

…but on my machine, this works fine:

mount("distri", "/ro", "fuse", MS_NODEV, "fd=3,rootmode=40000,user_id=0,group_id=0,allow_other,default_permissions,subtype=polefs") = 0

Which Linux version are you running this on? What are the steps to reproduce this issue in a clean installation?

[kungf]

Which Linux version are you running this on? What are the steps to reproduce this issue in a clean installation?

centos7 3.18.22 , do nothing special in after installation.
fusermount works fine in root.

[stapelberg]

So I set up a CentOS 7 VM (from CentOS-7-x86_64-Minimal-1908.iso) and ran yum -y update.

However, I get kernel version 3.10.0-1062.12.1.el7.x86_64, not 3.18.22?

Furthermore, mounting the sample file system (samples/mount_sample) works fine:

[root@localhost ~]# strace -fvy -s2048 -e mount /tmp/mount_sample --ready_file 1 -type flushfs --flushfs.flushes_file=2 -flushfs.fsyncs_file=2 -mount_point /mnt
[…]
[pid  9781] mount("", "/mnt", "fuse", MS_NOSUID|MS_NODEV, "fd=3,rootmode=40000,user_id=0,group_id=0,default_permissions") = 0
[…]

Can you please actually reproduce your problem in a clean VM and share the precise steps to reproduce?

[stapelberg]

Okay, so the issue only manifests itself once you start setting the Subtype FUSE mount option.