xfs: take m_growlock when running growfsrt

xfs: take m_growlock when running growfsrt

[ Upstream commit 16e1fbdce9c8d084863fd63cdaff8fb2a54e2f88 ]

Take the grow lock when we're expanding the realtime volume, like we do
for the other growfs calls.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Acked-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>