cannot unmount sshfs mounts when ssh connection is lost

[Jarl]

The description is from https://bugzilla.redhat.com/show_bug.cgi?id=728467, I consider the description very comprehensive, so I grabed it.

fusermount -u do not work after a broken ssh connection. The invalid mountpoint
is in a strage state that locks the ls command.

How reproducible:
always

---

Steps to Reproduce:
1.mount a remote ssh filesystem with sshfs
2.lost the ssh connection (wait for ``broken pipe or missing link errors, if
you quickly plus/unplug nothing happens), then replug the cable
3.try to umount the ssf filesystem with fusermount -u

---

Actual results:
1) I mount a distant folder:
su pierre;
cd ~; mkdir test;
sshfs <email address hidden>:/home/someone test;

This mount is sucessfull and can be tested
cat test/somefile; #WORKS
touch test/someotherfile; #WORKS

2) For some reason ssh connection is lost for a long time (a cat eat a wire, I
unpluged my ethernet cable or zombies from outer space decide to do so). Then I
repear the connection (re plug the cable and kill the zoombies).

3) LS FAILS (except for the user who has mounted the filesystem)

su root;
ll /home/pierre;
freeze the terminal (Ctrl +C do NOT work, but closing the terminal window and
opening a new one is a workaround).

Using autocompletion with tab tab freeze the terminal too.

su pierre;
ll /home/pierre;
drwxr-xr-x. 2 pierre pierre 4096 5 mai 2010 Bananas
d?????????? ? ? ? ? ? test

4) UMOUNT FAILS
su pierre;
fusermount -u /home/pierre/test;
fusermount: entry for /home/pierre/test not found in /etc/mtab

But fusermount lies:
cat /etc/mtab | grep test;
<email address hidden>:/home/someone /home/pierre/test fuse.sshfs
rw,nosuid,nodev,relatime,user_id=0,group_id=0,max_read=65536 0 0

su -;
umount /home/pierre/test;
Terminal freezes but Ctrl +C works.

---

Expected results:
fusermount -u should unmount the filesystem, not freeze the terminal
ls should work
even if ssh is lost, the mounted folder must be in a state that do not generate
strage bugs.

[Pierre (pierre-redhat-bugs)]

Description of problem:
fusermount -u do not work after a broken ssh connection. The invalid mountpoint is in a strage state that locks the ls command.

---

Version-Release number of selected component (if applicable):
fusermount version: 2.8.5
SSHFS version 2.2
FUSE library version: 2.8.5
fusermount version: 2.8.5
using FUSE kernel interface version 7.12

---

How reproducible:
always

---

Steps to Reproduce:
1.mount a remote ssh filesystem with sshfs
2.lost the ssh connection (wait for ``broken pipe or missing link errors, if you quickly plus/unplug nothing happens), then replug the cable
3.try to umount the ssf filesystem with fusermount -u

---

Actual results:
1) I mount a distant folder:
su pierre;
cd ~; mkdir test;
sshfs <email address hidden>:/home/someone test;

This mount is sucessfull and can be tested
cat test/somefile; #WORKS
touch test/someotherfile; #WORKS

2) For some reason ssh connection is lost for a long time (a cat eat a wire, I unpluged my ethernet cable or zombies from outer space decide to do so). Then I repear the connection (re plug the cable and kill the zoombies).

3) LS FAILS (except for the user who has mounted the filesystem)

su root;
ll /home/pierre;
freeze the terminal (Ctrl +C do NOT work, but closing the terminal window and opening a new one is a workaround).

Using autocompletion with tab tab freeze the terminal too.

su pierre;
ll /home/pierre;
drwxr-xr-x. 2 pierre pierre 4096 5 mai 2010 Bananas
d?????????? ? ? ? ? ? test

4) UMOUNT FAILS
su pierre;
fusermount -u /home/pierre/test;
fusermount: entry for /home/pierre/test not found in /etc/mtab

But fusermount lies:
cat /etc/mtab | grep test;
<email address hidden>:/home/someone /home/pierre/test fuse.sshfs rw,nosuid,nodev,relatime,user_id=0,group_id=0,max_read=65536 0 0

su -;
umount /home/pierre/test;
Terminal freezes but Ctrl +C works.

---

Expected results:
fusermount -u should unmount the filesystem, not freeze the terminal
ls should work
even if ssh is lost, the mounted folder must be in a state that do not generate strage bugs.

Additional info:
Workaround : reboot.

[Peter (peter-redhat-bugs)]

Hello.
Could you, please, try latest fuse-sshfs (2.3, in updates-testing). It should handle disconnects much more gracefully.

[Pierre (pierre-redhat-bugs)]

Things seems to work now ;)
Thank.

--- DETAILS ---

cd ~; mkdir test;
sshfs <email address hidden>:/home/someone test;

1) OK
cat test/somefile; #WORKS
touch test/someotherfile; #WORKS

2) ifconfig eth0 down #A zombie eat the cable

3) OK
su root;
ll /home/pierre;
drwxr-xr-x. 2 pierre pierre 4096 5 mai 2010 Bananas

su pierre
ll /home/pierre;
drwxr-xr-x. 2 pierre pierre 4096 5 mai 2010 Bananas

4)OK
su pierre;
fusermount -u /home/pierre/test;

OR

su -;
umount /home/pierre/test;

folder is sucessefully unmounted

[James Avery (avery-diku)]

Still a problem in 2017, 5 years after the bug report; Running lsof, fuser -km, or even ls of the mountpoint hangs so bad that even kill -9 doesn't work on them.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ken Sharp (kennybobs)]

What versions are being used?

[Jarl (jarl-dk)]

All version numbers can be found in the attached apport information file in comment #1.