Issue with idle-unmount and files being used
petrarca-arezzo opened this issue · 7 comments
I'm seeing a strage (I think) behaviour with the idle-unmount option - if I mount a cipherdir with the idle option on and have a file opened in an editior gocryptfs does unmount the directory. My expectation would be that it would be left mounted as long as files are in use/opened and only unmounts it once all files are closed. Manually unmounting gives an error as expected though.
A sample debug output looks like this:
Checking for idle (isIdle = false, open = 0): 2020-12-14 10:13:23.774914275 +0100 CET m=+81.285029634
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:14:38.775224258 +0100 CET m=+156.285339542
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:15:53.775592901 +0100 CET m=+231.285708140
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:17:08.776033063 +0100 CET m=+306.286148317
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:18:23.7764397 +0100 CET m=+381.286554924
Filesystem idle; unmounting: /home/user/secret
unmount: srv.Unmount returned /bin/fusermount: failed to unmount /home/user/secret: Device or resource busy
(code exit status 1)
Trying lazy unmount
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:19:39.091255942 +0100 CET m=+456.601371260
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:20:54.091621515 +0100 CET m=+531.601736754
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:22:09.091971152 +0100 CET m=+606.602086390
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:23:24.092327712 +0100 CET m=+681.602442945
Filesystem idle; unmounting: /home/user/secret
unmount: srv.Unmount returned /bin/fusermount: entry for /home/user/secret not found in /etc/mtab
(code exit status 1)
Trying lazy unmount
fusermount: entry for /home/user/secret not found in /etc/mtab
Checking for idle (isIdle = true, open = 0): 2020-12-14 10:24:39.40682465 +0100 CET m=+756.916939948
This is happening with
gocryptfs 1.7.1; go-fuse 0.0~git20190214.58dcd77; 2019-12-26 go1.13.5 linux/amd64
I think the problem is that the editor copies the file into memory, but does not keep it actually open. At least that's what nano seems to do:
Open file
$ nano /tmp/foo.txt
In second terminal check what files nano has open (note: foo.txt is not here)
$ lsof -p $(pgrep nano)
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
nano 14682 jakob cwd DIR 253,0 4096 2 /
nano 14682 jakob rtd DIR 253,0 4096 2 /
nano 14682 jakob txt REG 253,0 347200 6355383 /usr/bin/nano
nano 14682 jakob mem REG 253,0 223542144 6292603 /usr/lib/locale/locale-archive
nano 14682 jakob mem REG 253,0 37384 6298839 /usr/lib64/libdl-2.32.so
nano 14682 jakob mem REG 253,0 103104 6299797 /usr/lib64/libz.so.1.2.11
nano 14682 jakob mem REG 253,0 3222128 6293317 /usr/lib64/libc-2.32.so
nano 14682 jakob mem REG 253,0 191480 6298831 /usr/lib64/libtinfo.so.6.2
nano 14682 jakob mem REG 253,0 263104 6297444 /usr/lib64/libncursesw.so.6.2
nano 14682 jakob mem REG 253,0 182576 6309068 /usr/lib64/libmagic.so.1.0.0
nano 14682 jakob mem REG 253,0 26998 6817233 /usr/lib64/gconv/gconv-modules.cache
nano 14682 jakob mem REG 253,0 264360 6298832 /usr/lib64/ld-2.32.so
nano 14682 jakob 0u CHR 136,0 0t0 3 /dev/pts/0
nano 14682 jakob 1u CHR 136,0 0t0 3 /dev/pts/0
nano 14682 jakob 2u CHR 136,0 0t0 3 /dev/pts/0
What editor do you use? Can you check with lsof if it keeps the file open?
I tried it with a few different editors (nano, xed, emacs, atom). With all of them the directory gets unmounted after the idle-time even though files are in use (open in the editors with unsaved changes made).
Here some results after the gocryptfs-directory is mounted and four files opened in the editors with unsaved changes:
user@linux ~ $ uname -a
Linux linux 5.4.0-58-generic #64-Ubuntu SMP Wed Dec 9 08:16:25 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
user@linux ~ $ fusermount -u /home/user/secret
fusermount: failed to unmount /home/user/secret: Device or resource busy
user@linux ~ $ lsof -p $(pgrep nano) | grep home
nano 33555 user cwd DIR 0,55 4096 7004411 /home/user/secret
user@linux ~ $ lsof -p $(pgrep xed) | grep home
xed 33562 user cwd DIR 0,60 12288 6946824 /home/user
xed 33562 user mem REG 0,60 32768 6961704 /home/user/.local/share/gvfs-metadata/root-199bc02a.log
xed 33562 user mem REG 0,60 55476 6947290 /home/user/.local/share/gvfs-metadata/root
xed 33562 user mem REG 0,60 86057 6969237 /home/user/.config/dconf/user
xed 33562 user 2w REG 0,60 25446 6946963 /home/user/.xsession-errors
xed 33562 user 13r REG 0,60 55476 6947290 /home/user/.local/share/gvfs-metadata/root
xed 33562 user 14r REG 0,60 32768 6961704 /home/user/.local/share/gvfs-metadata/root-199bc02a.log
user@linux ~ $ lsof -p $(pgrep emacs) | grep home
emacs 33609 user cwd DIR 0,55 4096 7004411 /home/user/secret
emacs 33609 user mem REG 0,60 86057 6969237 /home/user/.config/dconf/user
emacs 33609 user 2w REG 0,60 25446 6946963 /home/user/.xsession-errors
user@linux ~ $ lsof -p $(pgrep atom) | grep home
lsof: status error on 33317: No such file or directory
lsof: status error on 33322: No such file or directory
lsof: status error on 33324: No such file or directory
lsof: status error on 33348: No such file or directory
lsof: status error on 33371: No such file or directory
lsof: status error on 33436: No such file or directory
lsof 4.93.2
latest revision: https://github.com/lsof-org/lsof
latest FAQ: https://github.com/lsof-org/lsof/blob/master/00FAQ
latest (non-formatted) man page: https://github.com/lsof-org/lsof/blob/master/Lsof.8
usage: [-?abhKlnNoOPRtUvVX] [+|-c c] [+|-d s] [+D D] [+|-E] [+|-e s] [+|-f[gG]]
[-F [f]] [-g [s]] [-i [i]] [+|-L [l]] [+m [m]] [+|-M] [-o [o]] [-p s]
[+|-r [t]] [-s [p:s]] [-S [t]] [-T [t]] [-u s] [+|-w] [-x [fl]] [--] [names]
Use the ``-h'' option to get more help information.
user@linux ~ $ mount | grep gocryptfs
/home/user/.secret on /home/user/secret type fuse.gocryptfs (rw,nosuid,nodev,relatime,user_id=1000,group_id=100,max_read=131072)
then after some (idle-) time:
user@linux ~ $ mount | grep gocryptfs
user@linux ~ $ fusermount -u /home/user/secret
fusermount: entry for /home/user/secret not found in /etc/mtab
user@linux ~ $
It seems that lsof (not working for me with 'atom') is just showing the mounted folder but not the actual file being edited; exception being xed which only shows the home directory under which the gocryptfs-folder is mounted.
I really hope, I'm not doing some dumb here; can someone reproduce (or not) what I'm seeing?
Nothing dumb :)
I can reproduce the behavior with nano. But I'm not sure what to do about it, as the file is not actually kept open by nano.
What puzzles me though is that if I open a file (with e.g. nano), I can't unmount the directory manually with fusermount. So it seems that fusermount is somehow recognizing the open file.
The first line of the lsof list shows that the mounted directory is in use (but not the actual file). So one might need to look for the directory being used, and not looking for a file being used (?):
user@linux ~ $ lsof -p $(pgrep nano) | grep home
nano 181767 user cwd DIR 0,58 4096 7004411 /home/user/secret
user@linux ~ $ lsof -p $(pgrep nano)
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
nano 181767 user cwd DIR 0,58 4096 7004411 /home/user/secret
nano 181767 user rtd DIR 8,1 4096 2 /
nano 181767 user txt REG 8,1 320136 2359348 /bin/nano
nano 181767 user mem REG 8,1 51832 14418433 /lib/x86_64-linux-gnu/libnss_files-2.31.so
nano 181767 user mem REG 8,1 105528 14418422 /lib/x86_64-linux-gnu/libnsl-2.31.so
nano 181767 user mem REG 8,1 57901 26493553 /usr/share/locale-langpack/de/LC_MESSAGES/nano.mo
nano 181767 user mem REG 8,1 6070224 25821215 /usr/lib/locale/locale-archive
nano 181767 user mem REG 8,1 18816 14418395 /lib/x86_64-linux-gnu/libdl-2.31.so
nano 181767 user mem REG 8,1 2029224 14418369 /lib/x86_64-linux-gnu/libc-2.31.so
nano 181767 user mem REG 8,1 192032 14418683 /lib/x86_64-linux-gnu/libtinfo.so.6.2
nano 181767 user mem REG 8,1 231504 14418180 /lib/x86_64-linux-gnu/libncursesw.so.6.2
nano 181767 user mem REG 8,1 55928 14418435 /lib/x86_64-linux-gnu/libnss_nis-2.31.so
nano 181767 user mem REG 8,1 43968 14418426 /lib/x86_64-linux-gnu/libnss_compat-2.31.so
nano 181767 user mem REG 8,1 27002 26223849 /usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache
nano 181767 user mem REG 8,1 191472 14418270 /lib/x86_64-linux-gnu/ld-2.31.so
nano 181767 user 0u CHR 136,1 0t0 4 /dev/pts/1
nano 181767 user 1u CHR 136,1 0t0 4 /dev/pts/1
nano 181767 user 2u CHR 136,1 0t0 4 /dev/pts/1
user@linux ~ $ fusermount -u secret
fusermount: failed to unmount /home/user/secret: Device or resource busy
That is true, however, try this:
cd /
nano /home/user/secret
PS: What I will do is to make the idle unmount behave like fusermount -u. That fixes the case:
cd /home/user
nano secret
But not that one:
cd /
nano /home/user/secret
Hello, I was having a similar problem.
In my case it was a process keypassxc-proxy.exe which remained after quitting KeyPassXC on Windows. (I am using gocryptfs from WSL, but using the mounted filesystem from Windows.)
I am noting it here since this page is what kagi offered as the first link when I searched for failed to unmount /root/gocryptfs-mnt/smallsync/plaintext: Device or resource busy.
Surely I will have this problem again in the future. Maybe someone else will as well, and will benefit from this note.