XfsFileStoreBackend: default to disabling extsize on xfs

This appears to be responsible for the deep scrub mismatches on some rbd
workloads.

Fixes: 8830
Signed-off-by: Samuel Just <sam.just@inktank.com>
Merge pull request #2103 from ceph/wip-8830

XfsFileStoreBackend: default to disabling extsize on xfs

Reviewed-by: Sage Weil <sage@redhat.com>
init-ceph: wrap daemon startup with systemd-run when running under systemd

We want to make sure the daemon runs in its own systemd environment.  Check
for systemd as pid 1 and, when present, use systemd-run -r <cmd> to do
this.

Probably fixes #7627

Signed-off-by: Sage Weil <sage@redhat.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Tested-by: Dan Mick <dan.mick@inktank.com>
rgw: don't try to wait for pending if list is empty

Fixes: #8846
Backport: firefly, dumpling

This was broken at ea68b9372319fd0bab40856db26528d36359102e. We ended
up calling wait_pending_front() when pending list was empty.
This commit also moves the need_to_wait check to a different place,
where we actually throttle (and not just drain completed IOs).

Reported-by: Sylvain Munaut <s.munaut@whatever-company.com>
Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
(cherry picked from commit f9f2417d7db01ecf2425039539997901615816a9)
Merge remote-tracking branch 'gh/next'