On Fri, Oct 31, 2014 at 09:23:27AM -0700, Rich Turner wrote:
> let’s first assume the contents of /etc/fstab are either not used or invalid 
> in mounting the subvolumes. given the following ‘df’ command, how do i know 
> which subvolume of the btrfs filesystem on /dev/sda3 is mounted at each mount 
> point (/, /var, /opt, /home)? i would have expected to see the mount option 
> used to define the subvolume (subvolid or subvol option) in /proc/mounts.

   I already answered this on IRC, but just for the record (and to
test whether my mail is working): it's in /proc/self/mountinfo. The
fourth field of each line is the location that the mountpoint came
from in the filesystem, which is what you're after.

   Hugo.

> # df
> Filesystem     1K-blocks    Used Available Use% Mounted on
> /dev/sda3        6839296 1698564   4903212  26% /
> devtmpfs          501464       0    501464   0% /dev
> tmpfs             507316       0    507316   0% /dev/shm
> tmpfs             507316    6720    500596   2% /run
> tmpfs             507316       0    507316   0% /sys/fs/cgroup
> /dev/sda3        6839296 1698564   4903212  26% /var
> /dev/sda3        6839296 1698564   4903212  26% /opt
> /dev/sda3        6839296 1698564   4903212  26% /home
> /dev/sda1         517868   93040    424828  18% /boot
> 
> # btrfs subvolume list -a --sort=+rootid /
> ID 257 gen 7800 top level 5 path <FS_TREE>/root
> ID 258 gen 4127 top level 5 path <FS_TREE>/home
> ID 259 gen 7801 top level 5 path <FS_TREE>/var
> ID 260 gen 7795 top level 5 path <FS_TREE>/opt
> 
> # uname -a
> Linux turner11.storix 3.10.0-123.el7.x86_64 #1 SMP Mon May 5 11:16:57 EDT 
> 2014 x86_64 x86_64 x86_64 GNU/Linux
> 
> # btrfs --version
> Btrfs v3.12
> 
> # btrfs fi show
> Label: rhel_turner11  uuid: cd3c0e50-d726-44e2-9bfa-19b11614136a
>       Total devices 1 FS bytes used 1.62GiB
>       devid    1 size 6.52GiB used 2.24GiB path /dev/sda3
> 
> Btrfs v3.12
> 
> # btrfs fi df /
> Data, single: total=1.98GiB, used=1.58GiB
> System, single: total=4.00MiB, used=16.00KiB
> Metadata, single: total=264.00MiB, used=36.03MiB
> 


> 
> 


-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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