xfs/529: fix bogus failure when realtime is configured

xfs/529: fix bogus failure when realtime is configured

If I have a realtime volume configured, this test will sometimes trip
over this:

XFS: Assertion failed: nmaps == 1, file: fs/xfs/xfs_dquot.c, line: 360
Call Trace:
 xfs_dquot_disk_alloc+0x3dc/0x400 [xfs 97e1fa8953d397b1fb9732df4de7fa9070bda501]
 xfs_qm_dqread+0xc9/0x190 [xfs 97e1fa8953d397b1fb9732df4de7fa9070bda501]
 xfs_qm_dqget+0xa8/0x230 [xfs 97e1fa8953d397b1fb9732df4de7fa9070bda501]
 xfs_qm_vop_dqalloc+0x160/0x600 [xfs 97e1fa8953d397b1fb9732df4de7fa9070bda501]
 xfs_setattr_nonsize+0x318/0x520 [xfs 97e1fa8953d397b1fb9732df4de7fa9070bda501]
 notify_change+0x30e/0x490
 chown_common+0x13e/0x1f0
 do_fchownat+0x8d/0xe0
 __x64_sys_fchownat+0x1b/0x20
 do_syscall_64+0x2b/0x80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7fa6985e2cae

The test injects the bmap_alloc_minlen_extent error, which refuses to
allocate file space unless it's exactly minlen long.  However, a
precondition of this injection point is that the free space on the data
device must be sufficiently fragmented that there are small free
extents.

However, if realtime and rtinherit are enabled, the punch-alternating
call will operate on a realtime file, which only serves to write 0x55
patterns into the realtime bitmap.  Hence the test preconditions are not
satisfied, so the test is not serving its purpose.

Fix it by disabling rtinherit=1 on the rootdir so that we actually
fragment the bnobt/cntbt as required.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>