From: Qian Yingjin <qian@ddn.com>
Date: Fri, 28 May 2021 03:56:12 +0000 (+0800)
Subject: LU-14724 nrs: TBF rule list broken when change rule rank
X-Git-Tag: 2.14.55~52
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=e688f29275deeadc0ef4faa01f166986bade301f

LU-14724 nrs: TBF rule list broken when change rule rank

When change rank of two adjacent rules in the TBF rule list in
@nrs_tbf_rule_change_rank():
	list_move(&rule->tr_linkage, next_rule->tr_linkage.prev);

The previous pointer of @next_rule is @rule, using list_move
directly will break the rule list.
In this patch, it use list_del + list_add to repace list_move to
avoid TBF rule broken.
And also add a test case sanityn test_77o for this bug.

Fixes: aa14b0b9a152 ("LU-8006 ptlrpc: specify ordering of TBF policy rules")
Change-Id: Ica30d3329f07914657ac2c4089d66f934021b763
Signed-off-by: Qian Yingjin <qian@ddn.com>
Reviewed-on: https://review.whamcloud.com/43925
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---

diff --git a/lustre/ptlrpc/nrs_tbf.c b/lustre/ptlrpc/nrs_tbf.c
index 32adf79..653b55e 100644
--- a/lustre/ptlrpc/nrs_tbf.c
+++ b/lustre/ptlrpc/nrs_tbf.c
@@ -390,7 +390,8 @@ nrs_tbf_rule_change_rank(struct ptlrpc_nrs_policy *policy,
 	if (!next_rule)
 		GOTO(out_put, rc = -ENOENT);
 
-	list_move(&rule->tr_linkage, next_rule->tr_linkage.prev);
+	/* rules may be adjacent in same list, so list_move() isn't safe here */
+	list_move_tail(&rule->tr_linkage, &next_rule->tr_linkage);
 	nrs_tbf_rule_put(next_rule);
 out_put:
 	nrs_tbf_rule_put(rule);
diff --git a/lustre/tests/sanityn.sh b/lustre/tests/sanityn.sh
index 636ef021..91f9f9a 100755
--- a/lustre/tests/sanityn.sh
+++ b/lustre/tests/sanityn.sh
@@ -4416,6 +4416,19 @@ test_77n() { #LU-10802
 }
 run_test 77n "check wildcard support for TBF JobID NRS policy"
 
+test_77o() {
+	(( $OST1_VERSION > $(version_code 2.14.54) )) ||
+        	skip "need OST > 2.14.54"
+
+	do_facet mds1 $LCTL set_param mds.MDS.mdt.nrs_policies="tbf\ nid"
+	do_facet mds1 $LCTL set_param mds.MDS.mdt.nrs_tbf_rule="start\ name\ nid={192.168.*.*@tcp}\ rate=10000"
+	do_facet mds1 $LCTL set_param mds.MDS.mdt.nrs_tbf_rule="start\ name1\ nid={192.168.*.*@tcp}\ rate=10000"
+	do_facet mds1 $LCTL set_param mds.MDS.mdt.nrs_tbf_rule="change\ name1\ rank=name"
+	do_facet mds1 $LCTL set_param mds.MDS.mdt.nrs_tbf_rule="stop\ name"
+	do_facet mds1 $LCTL set_param mds.MDS.mdt.nrs_policies="fifo"
+}
+run_test 77o "Changing rank should not panic"
+
 test_78() { #LU-6673
 	local rc