Description of problem:
I find this bug when I ran xfstests generic/082 on XFS. generic/082 failed as:
  group quota on SCRATCH_MNT (SCRATCH_DEV) is off
  user quota on SCRATCH_MNT (SCRATCH_DEV) is off

But the SCRATCH_MNT is mount with usrquota,grpquota.

For skip some useless steps in generic/082, I just run:
1. mkfs.xfs /dev/sda2

2. mount /dev/sda2 /mnt/xfstests/mnt1 -o usrquota,grpquota

3. mount -l|grep /dev/sda2
/dev/sda2 on /mnt/xfstests/mnt1 type xfs (rw,usrquota,grpquota)

4. cat /proc/mounts|grep /dev/sda2
/dev/sda2 /mnt/xfstests/mnt1 xfs rw,seclabel,relatime,attr2,delaylog,usrquota,grpquota 0 0

5. quotacheck -ug /mnt/xfstests/mnt1
quotacheck: Cannot find filesystem to check or filesystem not mounted with quota option.

6. quotaon /mnt/xfstests/mnt1
quotaon: Enforcing group quota already on /dev/sda2
quotaon: Enforcing user quota already on /dev/sda2

7. quotaon -p /mnt/xfstests/mnt1
group quota on /mnt/xfstests/mnt1 (/dev/sda2) is off
user quota on /mnt/xfstests/mnt1 (/dev/sda2) is off

8. xfs_quota -x -c "state -ug" /mnt/xfstests/mnt1
User quota state on /mnt/xfstests/mnt1 (/dev/sda2)
  Accounting: ON
  Enforcement: ON
  Inode: #131 (1 blocks, 1 extents)
Group quota state on /mnt/xfstests/mnt1 (/dev/sda2)
  Accounting: ON
  Enforcement: ON
  Inode: #132 (1 blocks, 1 extents)
Blocks grace time: [7 days 00:00:30]
Inodes grace time: [7 days 00:00:30]
Realtime Blocks grace time: [7 days 00:00:30]


So 
step#3 and step#4 show I really mount with quota option
step#5 and step#7 show quota-tools report quota is off
step#8 xfs_quota shows quota is on.

By the way, this failure can't be found on ext3/4.

Actual results:
quotaon -p show quota off if mount xfs with usrquota,grpquota

Expected results:
quotaon -p show quota on if mount xfs with usrquota,grpquota

Additional info:
I try to strace quotaon -p $mnt:
on RHEL-6.8, the quotactl() system call shows as:
---
[root@sgi-uv30-01 ~]# strace -e quotactl quotaon -p /mnt/xfstests/mnt1
quotactl(Q_GETFMT|GRPQUOTA, "/dev/sda2", 0, 0x7ffdc57e848c) = -1 ESRCH (No such process)
group quota on /mnt/xfstests/mnt1 (/dev/sda2) is off
quotactl(Q_GETFMT|USRQUOTA, "/dev/sda2", 0, 0x7ffdc57e848c) = -1 ESRCH (No such process)
user quota on /mnt/xfstests/mnt1 (/dev/sda2) is off
+++ exited with 0 +++
---

on RHEL-7, no this bug. quotaon -p can report quota on. its strace output as:
---
[root@ibm-x3650m4-10 ~]# strace -e quotactl quotaon -p /mnt/xfstests/mnt1                                              
quotactl(Q_XGETQSTAT|GRPQUOTA, "/dev/mapper/rhel_ibm--x3650m4--10-xfscratch", 0, {version=1, ...}) = 0
group quota on /mnt/xfstests/mnt1 (/dev/mapper/rhel_ibm--x3650m4--10-xfscratch) is on
quotactl(Q_XGETQSTAT|USRQUOTA, "/dev/mapper/rhel_ibm--x3650m4--10-xfscratch", 0, {version=1, ...}) = 0
user quota on /mnt/xfstests/mnt1 (/dev/mapper/rhel_ibm--x3650m4--10-xfscratch) is on
+++ exited with 2 +++
---

on RHEL-6.8, strace xfs_quota -x -c "state -ug" show as:
---
quotactl(Q_XGETQSTAT|USRQUOTA, "/dev/sda2", 0, {version=1, ...}) = 0
User quota state on /mnt/xfstests/mnt1 (/dev/sda2)
  Accounting: ON
  Enforcement: ON
  Inode: #131 (1 blocks, 1 extents)
Group quota state on /mnt/xfstests/mnt1 (/dev/sda2)
  Accounting: ON
  Enforcement: ON
  Inode: #132 (1 blocks, 1 extents)
Blocks grace time: [7 days 00:00:30]
Inodes grace time: [7 days 00:00:30]
Realtime Blocks grace time: [7 days 00:00:30]
+++ exited with 0 +++
---

Both RHEL-7 quotaon and xfs_quota use Q_XGETQSTAT, but RHEL-6 quotaon use Q_GETFMT. That's the difference.

BTW, I can reproduce this bug on upstream linux 4.5.0-rc2 on RHEL-6.8. So I think it's not a RHEL-6 kernel bug.