gfs2: Revert "ignore negated quota changes"

BugLink: https://bugs.launchpad.net/bugs/2097393

[ Upstream commit 4b4b6374dc6134849f2bdca81fa2945b6ed6d9fc ]

Commit 4c6a08125f ("gfs2: ignore negated quota changes") skips quota
changes with qd_change == 0 instead of writing them back, which leaves
behind non-zero qd_change values in the affected slots.  The kernel then
assumes that those slots are unused, while the qd_change values on disk
indicate that they are indeed still in use.  The next time the
filesystem is mounted, those invalid slots are read in from disk, which
will cause inconsistencies.

Revert that commit to avoid filesystem corruption.

This reverts commit 4c6a08125f.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>

fs/gfs2/quota.c

@@ -467,17 +467,6 @@ static bool qd_grab_sync(struct gfs2_sbd *sdp, struct gfs2_quota_data *qd,
 	    qd->qd_sync_gen >= sync_gen)
 		return false;
 
-	/*
-	 * If qd_change is 0 it means a pending quota change was negated.
-	 * We should not sync it, but we still have a qd reference and slot
-	 * reference taken by gfs2_quota_change -> do_qc that need to be put.
-	 */
-	if (!qd->qd_change && test_and_clear_bit(QDF_CHANGE, &qd->qd_flags)) {
-		slot_put(qd);
-		qd_put(qd);
-		return false;
-	}
-
 	if (!lockref_get_not_dead(&qd->qd_lockref))
 		return false;