AFAICT this looks like a bug in the kernel? You have this entry:
379 28 0:56 / /mnt/wd rw,relatime shared:704
-
cifs //192.168.1.109/WD (USB)
rw,vers=3.0,cache=strict,username=censored,uid=1000,noforceuid,gid=132,noforcegid,addr=192.168.1.109,file_mode=0771,dir_mode=0771,soft,nounix,serverino,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1
The mountinfor should contain only 11 fields separated with whitespace, for this particular like there’s 12 fields. The manpage isn’t too informative:
The file contains lines of the form:
36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
Specifically, the CIFS share name WD (USB) is what introduces an additional space. I don’t know why there is no quoting or the space hasn’t been replaced with %20 or some other encoding.
I think we may want to be less strict about parsing mountinfo. However it’s hard to tell bad input from a valid but quirky one. You can temporarily unmount the problematic share, at which point snap removal should be working again.