growfs supports growing mounted filesystems (writes are temporarily suspended while the grow happens). Drop the check for fs_clean == 0 to restore this case. Leave fs_flags check for FS_UNCLEAN or FS_NEEDSFSCK which represent the state of the filesystem when it was mounted, and fsck should be run first if they are set.
PR: 253754
Fixes: 6eb925f8450f ("Filesystem utilities that modify the...")