fix(dracut.sh): do not add device if find_block_device returns an error

[aafeijoo-suse]

If find_block_device returns an error, the device must not be added to the list of host devices. E.g., a system with /etc mounted as overlay is pushing the empty string '' as host device.

//usr/bin/dracut@1658(): readlink -f /etc
/usr/bin/dracut@1658(): mp=/etc
/usr/bin/dracut@1659(): mountpoint /etc
//usr/bin/dracut@1660(): find_block_device /etc
//usr/lib/dracut/dracut-functions.sh@366(find_block_device): local _dev _majmin _find_mpt
//usr/lib/dracut/dracut-functions.sh@367(find_block_device): _find_mpt=/etc
//usr/lib/dracut/dracut-functions.sh@369(find_block_device): [[ '' != yes ]]
//usr/lib/dracut/dracut-functions.sh@370(find_block_device): [[ -d /etc/. ]]
//usr/lib/dracut/dracut-functions.sh@371(find_block_device): findmnt -e -v -n -o MAJ:MIN,SOURCE --target /etc
//usr/lib/dracut/dracut-functions.sh@372(find_block_device): read -r _majmin _dev
//usr/lib/dracut/dracut-functions.sh@373(find_block_device): [[ -b overlay ]]
//usr/lib/dracut/dracut-functions.sh@384(find_block_device): [[ overlay == *:* ]]
//usr/lib/dracut/dracut-functions.sh@372(find_block_device): read -r _majmin _dev
//usr/lib/dracut/dracut-functions.sh@372(find_block_device): '[' -n '' ']'
//usr/lib/dracut/dracut-functions.sh@389(find_block_device): return 1
//usr/lib/dracut/dracut-functions.sh@393(find_block_device): [[ ! -f /etc/fstab ]]
//usr/lib/dracut/dracut-functions.sh@395(find_block_device): findmnt -e --fstab -v -n -o MAJ:MIN,SOURCE --target /etc
//usr/lib/dracut/dracut-functions.sh@396(find_block_device): read -r _majmin _dev
//usr/lib/dracut/dracut-functions.sh@397(find_block_device): [[ -n '' ]]
//usr/lib/dracut/dracut-functions.sh@398(find_block_device): _dev=overlay
//usr/lib/dracut/dracut-functions.sh@399(find_block_device): unset _majmin
//usr/lib/dracut/dracut-functions.sh@401(find_block_device): [[ -b overlay ]]
//usr/lib/dracut/dracut-functions.sh@410(find_block_device): [[ overlay == *:* ]]
//usr/lib/dracut/dracut-functions.sh@396(find_block_device): read -r _majmin _dev
//usr/lib/dracut/dracut-functions.sh@396(find_block_device): '[' -n '' ']'
//usr/lib/dracut/dracut-functions.sh@415(find_block_device): return 1
//usr/lib/dracut/dracut-functions.sh@418(find_block_device): return 1
/usr/bin/dracut@1660(): _dev=
//usr/bin/dracut@1661(): readlink -f /dev/block/
/usr/bin/dracut@1661(): _bdev=/dev/block
/usr/bin/dracut@1662(): [[ -b /dev/block ]]
/usr/bin/dracut@1663(): [[ /etc == \/ ]]
/usr/bin/dracut@1664(): push_host_devs ''

Checklist

• I have tested it locally
• I have reviewed and updated any documentation if relevant
• I am providing new code and test(s) for it

Fixes #2592

[stale]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.

[stale]

This issue is being marked as stale because it has not had any recent activity. It will be closed if no further activity occurs. If this is still an issue in the latest release of Dracut and you would like to keep it open please comment on this issue within the next 7 days. Thank you for your contributions.