I have an s3fs-fuse "device" mounted at /mnt/s3. I want to unmount it so that I can remount it with the mp_umask flag so that chroot will work properly.

The command should be:

fusermount -u /mnt/s3

Unfortunately the result is:

fusermount: failed to unmount /mnt/s3: Device or resource busy

That's not helpful. Shouldn't be this hard!


You can use lsof to figure out which files are still open.

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The command that worked was:

umount -l /mnt/s3
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  • 1
    This might not unmount the filesystem if one of the opens is long-lived; it is better to actually close the open files. – Andrew Gaul Feb 1 '19 at 18:32
  • 1
    In my case there were no open files, unmounting using that command did work for me. – Aftab Naveed Jun 4 '19 at 0:45

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