Subject: bug#22199: Bug in coreutils for Linux Mint?? Package coreutils_8.21-1ubuntu5.3_amd64

From: Dave <[email-masked]>
Date: Thu, 17 Dec 2015 18:23:29 -0600

df's output shows this on a standard run(df with no flags):

Filesystem     1K-blocks      Used Available Use% Mounted on
udev             1953632         4   1953628   1% /dev
tmpfs             400436      1216    399220   1% /run
/dev/sda1      957218452 302330152 606241340  34% /
none                   4         0         4   0% /sys/fs/cgroup
none                5120         0      5120   0% /run/lock
none             2002168         8   2002160   1% /run/shm
none              102400         4    102396   1% /run/user
/dev/sdb1      957218452 302510240 606061252  34% /mnt/bkup/device2

But when I mount an external USB disk that's on /dev/sdc1, df shows this 
output:

Filesystem     1K-blocks      Used Available Use% Mounted on
udev             1953632         4   1953628   1% /dev
tmpfs             400436      1272    399164   1% /run
/dev/sdc1      957218452 302334136 606237356  34% /
none                   4         0         4   0% /sys/fs/cgroup
none                5120         0      5120   0% /run/lock
none             2002168         8   2002160   1% /run/shm
none              102400         4    102396   1% /run/user
/dev/sdb1      957218452 302498156 606073336  34% /mnt/bkup/device2
/dev/sdc1      957218452 302564064 606007428  34% /mnt/bkup/externaldevice

The filesystem of "/" has mysteriously changed (in appearance) to 
/dev/sdc1?!  All I did was mount the /dev/sdc1 device.  In fact, 
/dev/sdc1 is ONLY mounted at /mnt/bkup/externaldevice, and the mounted 
filesystem on "/" is still /dev/sda1.  I tested by writing a couple of 
files, plus mount shows the correct info:

/dev/sda1 on / type ext4 (rw,errors=remount-ro)
/dev/sdb1 on /mnt/bkup/device2 type ext4 (rw)

If I unmount /mnt/bkup/externaldevice, df still shows /dev/sdc1 as the 
"/" filesystem for a small amount of time (10-20 seconds) and then it 
goes back to the correct filesystem of /dev/sda1.

What is going on??  This only happened after upgrading to the package of 
coreutils mentioned in the subject, it was not doing this previously.  
Also, to note, the first two lines of the df output regarding udev and 
tmpfs did not appear until this version either.  I did see in the 
changelog that df was updated to display some additional information, so 
perhaps it has to do with that??

-David