Description of problem: The fstrim.service of the util-linux package executes fstrim -a. This runs fstrim on each mountpoint, with btrfs it runs it on each subvolume. For a system which easily has 15 subvolume fstrim is executed 15 times on the same device. Please apply the following patch: https://git.kernel.org/cgit/utils/util-linux/util-linux.git/commit/?id=afa382f2e087b71c9e626144f2f313abc42ad594
util-linux-2.30-1.fc26 has been submitted as an update to Fedora 26. https://bodhi.fedoraproject.org/updates/FEDORA-2017-0d905dbef8
util-linux-2.30-1.fc26 has been pushed to the Fedora 26 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2017-0d905dbef8
util-linux-2.30-1.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.