Why does newly installed RHEL7 machine using btrfs partitioning fail to boot and goes into dracut shell?

Issue

• Why does newly installed RHEL7 machine using btrfs partitioning fail to boot and goes into dracut shell?
• One of the servers is not booting up and going into maintenance mode.
• The partitioning used is as follows.

clearpart --all --initlabel --drives=sda,sdb,sdc
part /boot --fstype=ext4 --size 512 --ondisk=sda
part swap  --size 1000 --fstype=swap --ondisk=sda
part btrfs.01 --size=6000 --ondisk=sda
part btrfs.02 --size=6000 --ondisk=sdb
part btrfs.03 --size=6000 --ondisk=sdc
btrfs none --data=0 --metadata=1 --label=rhel7 btrfs.01 btrfs.02 btrfs.03
btrfs / --subvol --name=root LABEL=rhel7
btrfs /home --subvol --name=home rhel7
btrfs /var --subvol --name=var   rhel7
btrfs /usr --subvol --name=var   rhel7
btrfs /tmp --subvol --name=tmp   rhel7
btrfs /opt --subvol --name=opt   rhel7

• The file rdsosreport.txt shows the following error messages.

[   88.465596] newrhel7 systemd[1]: Mounting /sysroot/usr...
[   88.470283] newrhel7 systemd[1]: Reloading.
[   88.468720] newrhel7 kernel: btrfs: device label rhel7 devid 3 transid 54 /dev/sdc1
[   88.471305] newrhel7 mount[313]: mount: /dev/sdc1 is already mounted or /sysroot/usr busy
[   88.488869] newrhel7 systemd[1]: sysroot-usr.mount mount process exited, code=exited status=32
[   88.489138] newrhel7 systemd[1]: Failed to mount /sysroot/usr.
[   88.489343] newrhel7 systemd[1]: Dependency failed for Initrd File Systems.
[   88.489705] newrhel7 systemd[1]: Triggering OnFailure= dependencies of initrd-fs.target.
[   88.489916] newrhel7 systemd[1]: Unit sysroot-usr.mount entered failed state.
[   88.490136] newrhel7 systemd[1]: Stopped dracut pre-pivot and cleanup hook.
[   88.490351] newrhel7 systemd[1]: Stopped target Initrd Default Target.
[   88.490522] newrhel7 systemd[1]: Stopped dracut mount hook.
[   88.490716] newrhel7 systemd[1]: Stopping dracut initqueue hook...
[   88.490886] newrhel7 systemd[1]: Stopped dracut initqueue hook.
[   88.491113] newrhel7 systemd[1]: Stopping Reload Configuration from the Real Root...