Log AFR quorum stats in io-stats translator.

Summary:
Add AFR quorum state to io-stats translator.

Sample output:

{
  "storage.gluster.nfsd.test-replicate-0.has-quorum": "1",
  "storage.gluster.nfsd.test-replicate-0.quorum-threshold": "1",
  "storage.gluster.nfsd.test-replicate-1.has-quorum": "1",
  "storage.gluster.nfsd.test-replicate-1.quorum-threshold": "1"
}

The quorum-threshold field shows the number of bricks that can be
lost while still maintaining quorum. Negative numbers indicate
that quorum has been lost and show the number of bricks that must
be brought online to restore quorum.

Additionally, I found that the code contained both
afr_have_quorum() and afr_has_quorum(), which were mostly
cut-n-pasted copies of each other, but with subtle differences.

Mercifully, afr_have_quorum() was totally unused, so I nuked it in
passing.

This is a port of D4089969 to 3.8.

Test Plan: Run, observe stats output. Kill brick, observe proper change. fb-smoke.

Reviewers: #posix_storage, sshreyas

Reviewed By: sshreyas

Subscribers: sshreyas

Differential Revision: https://phabricator.intern.facebook.com/D4089969

Change-Id: Ifddb351aebfe63998846bb52be8942415ce4c1a9
Reviewed-on: https://review.gluster.org/18188
Reviewed-by: Shreyas Siravara <sshreyas@fb.com>
Smoke: Gluster Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

0 files changed, 0 insertions, 0 deletions