Issue: The device number shown in `stat` output does not match the device
numbers of any of the devices used by the filesystem.
On my system:
$ stat --version | head -n 1
stat (GNU coreutils) 8.32
$ cat /etc/os-release | fgrep -i pretty
PRETTY_NAME="openSUSE Leap 15.3"
$ ls -l /dev/nvme0n1p6 /dev/nvme1n1p3
brw-rw---- 1 root disk 259, 6 Jan 12 09:29 /dev/nvme0n1p6
brw-rw---- 1 root disk 259, 12 Jan 12 09:29 /dev/nvme1n1p3
$ fgrep home /etc/crypttab
cr_home0 /dev/disk/by-id/nvme-RETRACTED1-part6
cr_home1 /dev/disk/by-id/nvme-RETRACTED2-part3
$ ls -l /dev/mapper/cr_home?
lrwxrwxrwx 1 root root 7 Jan 12 09:29 /dev/mapper/cr_home0 -> ../dm-6
lrwxrwxrwx 1 root root 7 Jan 12 09:30 /dev/mapper/cr_home1 -> ../dm-5
$ ls -l /dev/dm-[56]
brw-rw---- 1 root disk 254, 5 Jan 12 09:30 /dev/dm-5
brw-rw---- 1 root disk 254, 6 Jan 12 09:29 /dev/dm-6
$ fgrep home /etc/fstab
/dev/mapper/cr_home0 /home btrfs defaults
0 0
$ history | fgrep cr_home | tail -n 3 | head -n 2
108 2022-01-05 17:01:22 mkfs.btrfs /dev/mapper/cr_home0
141 2022-01-05 17:16:49 btrfs device add /dev/mapper/cr_home1 /home
$ touch /home/test
$ stat /home/test | fgrep -i device
Device: 3ch/60d Inode: 2143351 Links: 1
$ ls -l /dev | grep "^b" | fgrep 60 | wc -l
0
Expected behaviour: Device should be one (or more) of
fe06h/65030d <-- most expected as this is the primary btrfs device
fe05h/65029d <-- the 2nd device (/dev/cr_home1)
10306h/66310d <-- backing device for cr_home0 (/dev/nvme0n1p6)
1030ch/66316d <-- backing device for cr_home1 (/dev/nvme1n1p3)
10300h/66304d <-- SSD 1 (/dev/nvme0n1)
10309h/66313d <-- SSD 2 (/dev/nvme1n1)
Speculation: Searching the mailing list for stat + major on https://
www.gnu.org/software/coreutils/ shows results indicating that stat uses only 8
bit for major and minor. However, since kernel 2.6.0 according to https://
stackoverflow.com/questions/14833467/maximum-values-of-major-and-minor-
numbers-in-linux , the major has 12 bit and the minor 20 bit. Output above
shows a major with at least 9 bits that may confuse `stat` if it doesn't stay
with the immediate device number of the top level dm-crypt device.
