From 9c64da63c028a800020bc9f7e139b8ba2d8f11ed Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Thu, 31 Oct 2019 10:39:20 +0000 Subject: quota: Check that quota is not dirty before release commit df4bb5d128e2c44848aeb36b7ceceba3ac85080d upstream. There is a race window where quota was redirted once we drop dq_list_lock inside dqput(), but before we grab dquot->dq_lock inside dquot_release() TASK1 TASK2 (chowner) ->dqput() we_slept: spin_lock(&dq_list_lock) if (dquot_dirty(dquot)) { spin_unlock(&dq_list_lock); dquot->dq_sb->dq_op->write_dquot(dquot); goto we_slept if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { spin_unlock(&dq_list_lock); dquot->dq_sb->dq_op->release_dquot(dquot); dqget() mark_dquot_dirty() dqput() goto we_slept; } So dquot dirty quota will be released by TASK1, but on next we_sleept loop we detect this and call ->write_dquot() for it. XFSTEST: https://github.com/dmonakhov/xfstests/commit/440a80d4cbb39e9234df4d7240aee1d551c36107 Link: https://lore.kernel.org/r/20191031103920.3919-2-dmonakhov@openvz.org Signed-off-by: Dmitry Monakhov Signed-off-by: Jan Kara Signed-off-by: Ben Hutchings --- fs/ocfs2/quota_global.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ocfs2') diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c index b990a62cff50..5524b5bad5ba 100644 --- a/fs/ocfs2/quota_global.c +++ b/fs/ocfs2/quota_global.c @@ -714,7 +714,7 @@ static int ocfs2_release_dquot(struct dquot *dquot) mutex_lock(&dquot->dq_lock); /* Check whether we are not racing with some other dqget() */ - if (atomic_read(&dquot->dq_count) > 1) + if (dquot_is_busy(dquot)) goto out; /* Running from downconvert thread? Postpone quota processing to wq */ if (current == osb->dc_task) { -- cgit v1.2.3