xfs: fix missing ILOCK unlock when xfs_setattr_nonsize fails due to EDQUOT

mainline inclusion
from mainline-v5.3-rc6
commit 1fb254aa
category: bugfix
bugzilla: 13690
CVE: CVE-2019-15538

-------------------------------------------------

Benjamin Moody reported to Debian that XFS partially wedges when a chgrp
fails on account of being out of disk quota.  I ran his reproducer
script:

(and then as user dummy)

$ dd if=/dev/urandom bs=1M count=50 of=/mnt/dummy/foo
$ chgrp plugdev /mnt/dummy/foo

and saw:
Reviewed-by: zhengbin <zhengbin13@huawei.com>

================================================
WARNING: lock held when returning to user space!
5.3.0-rc5 #rc5 Tainted: G        W
------------------------------------------------
chgrp/47006 is leaving the kernel with locks still held!
1 lock held by chgrp/47006:
 #0: 000000006664ea2d (&xfs_nondir_ilock_class){++++}, at: xfs_ilock+0xd2/0x290 [xfs]

...which is clearly caused by xfs_setattr_nonsize failing to unlock the
ILOCK after the xfs_qm_vop_chown_reserve call fails.  Add the missing
unlock.

Reported-by:  <benjamin.moody@gmail.com>
Fixes: 253f4911 ("xfs: better xfs_trans_alloc interface")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Reviewed-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>