Usage:
 fstrim [options] -A|-a|<mountpoint>

Discard unused blocks on a mounted filesystem.

Options:
 -a, --all                trim mounted filesystems
 -A, --fstab              trim filesystems from /etc/fstab
 -I, --listed-in <list>   trim filesystems listed in specified files
 -o, --offset <num>       the offset in bytes to start discarding from
 -l, --length <num>       the number of bytes to discard
 -m, --minimum <num>      the minimum extent length to discard
 -t, --types <list>       limit the set of filesystem types
 -v, --verbose            print number of discarded bytes
     --quiet-unsupported  suppress error messages if trim unsupported
 -n, --dry-run            does everything, but trim

 -h, --help          display this help
 -V, --version       display version

Arguments:
 Values for <num> may be followed by a suffix: KiB, MiB,
 GiB, TiB, PiB, EiB, ZiB, or YiB (where the "iB" is optional).

For more details see fstrim(8).