[dm-devel] [PATCH] Revert "raid5: make release_stripe lockless" because it causes test regression
Mikulas Patocka
mpatocka at redhat.com
Fri Nov 22 20:07:08 UTC 2013
Revert 773ca82fa1ee58dd1bf88b6a5ca385ec83a2cac6 and
d265d9dc1d25a69affc21ae9fe5004b9d09c10ef.
The lvm testsuite (from
ftp://sources.redhat.com/pub/lvm2/LVM2.2.02.104.tgz) fails with unkillable
lvm and dmsetup processes on kernel 3.12. The testsuite passes on 3.11.
Bisect shows that the failure is caused by patch
773ca82fa1ee58dd1bf88b6a5ca385ec83a2cac6. When I revert this patch on 3.12
kernel, the testsuite finishes and there are no unkillable processes.
Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Cc: stable at kernel.org # 3.12
---
drivers/md/raid5.c | 70 +++--------------------------------------------------
drivers/md/raid5.h | 3 --
2 files changed, 5 insertions(+), 68 deletions(-)
Index: linux-3.12-fast/drivers/md/raid5.c
===================================================================
--- linux-3.12-fast.orig/drivers/md/raid5.c 2013-11-21 22:45:20.000000000 +0100
+++ linux-3.12-fast/drivers/md/raid5.c 2013-11-21 23:39:01.000000000 +0100
@@ -293,62 +293,12 @@ static void __release_stripe(struct r5co
do_release_stripe(conf, sh);
}
-static struct llist_node *llist_reverse_order(struct llist_node *head)
-{
- struct llist_node *new_head = NULL;
-
- while (head) {
- struct llist_node *tmp = head;
- head = head->next;
- tmp->next = new_head;
- new_head = tmp;
- }
-
- return new_head;
-}
-
-/* should hold conf->device_lock already */
-static int release_stripe_list(struct r5conf *conf)
-{
- struct stripe_head *sh;
- int count = 0;
- struct llist_node *head;
-
- head = llist_del_all(&conf->released_stripes);
- head = llist_reverse_order(head);
- while (head) {
- sh = llist_entry(head, struct stripe_head, release_list);
- head = llist_next(head);
- /* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
- smp_mb();
- clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
- /*
- * Don't worry the bit is set here, because if the bit is set
- * again, the count is always > 1. This is true for
- * STRIPE_ON_UNPLUG_LIST bit too.
- */
- __release_stripe(conf, sh);
- count++;
- }
-
- return count;
-}
-
static void release_stripe(struct stripe_head *sh)
{
struct r5conf *conf = sh->raid_conf;
unsigned long flags;
- bool wakeup;
- if (test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
- goto slow_path;
- wakeup = llist_add(&sh->release_list, &conf->released_stripes);
- if (wakeup)
- md_wakeup_thread(conf->mddev->thread);
- return;
-slow_path:
local_irq_save(flags);
- /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
do_release_stripe(conf, sh);
spin_unlock(&conf->device_lock);
@@ -596,8 +546,7 @@ get_active_stripe(struct r5conf *conf, s
if (atomic_read(&sh->count)) {
BUG_ON(!list_empty(&sh->lru)
&& !test_bit(STRIPE_EXPANDING, &sh->state)
- && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state)
- && !test_bit(STRIPE_ON_RELEASE_LIST, &sh->state));
+ && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
} else {
if (!test_bit(STRIPE_HANDLE, &sh->state))
atomic_inc(&conf->active_stripes);
@@ -4293,10 +4242,6 @@ static void raid5_unplug(struct blk_plug
*/
smp_mb__before_clear_bit();
clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
- /*
- * STRIPE_ON_RELEASE_LIST could be set here. In that
- * case, the count is always > 1 here
- */
__release_stripe(conf, sh);
cnt++;
}
@@ -5007,13 +4952,11 @@ static void raid5_do_work(struct work_st
handled = 0;
spin_lock_irq(&conf->device_lock);
while (1) {
- int batch_size, released;
-
- released = release_stripe_list(conf);
+ int batch_size;
batch_size = handle_active_stripes(conf, group_id, worker);
worker->working = false;
- if (!batch_size && !released)
+ if (!batch_size)
break;
handled += batch_size;
}
@@ -5048,9 +4991,7 @@ static void raid5d(struct md_thread *thr
spin_lock_irq(&conf->device_lock);
while (1) {
struct bio *bio;
- int batch_size, released;
-
- released = release_stripe_list(conf);
+ int batch_size;
if (
!list_empty(&conf->bitmap_list)) {
@@ -5075,7 +5016,7 @@ static void raid5d(struct md_thread *thr
}
batch_size = handle_active_stripes(conf, ANY_GROUP, NULL);
- if (!batch_size && !released)
+ if (!batch_size)
break;
handled += batch_size;
@@ -5503,7 +5444,6 @@ static struct r5conf *setup_conf(struct
INIT_LIST_HEAD(&conf->delayed_list);
INIT_LIST_HEAD(&conf->bitmap_list);
INIT_LIST_HEAD(&conf->inactive_list);
- init_llist_head(&conf->released_stripes);
atomic_set(&conf->active_stripes, 0);
atomic_set(&conf->preread_active_stripes, 0);
atomic_set(&conf->active_aligned_reads, 0);
Index: linux-3.12-fast/drivers/md/raid5.h
===================================================================
--- linux-3.12-fast.orig/drivers/md/raid5.h 2013-11-21 23:29:32.000000000 +0100
+++ linux-3.12-fast/drivers/md/raid5.h 2013-11-21 23:29:35.000000000 +0100
@@ -197,7 +197,6 @@ enum reconstruct_states {
struct stripe_head {
struct hlist_node hash;
struct list_head lru; /* inactive_list or handle_list */
- struct llist_node release_list;
struct r5conf *raid_conf;
short generation; /* increments with every
* reshape */
@@ -324,7 +323,6 @@ enum {
STRIPE_OPS_REQ_PENDING,
STRIPE_ON_UNPLUG_LIST,
STRIPE_DISCARD,
- STRIPE_ON_RELEASE_LIST,
};
/*
@@ -463,7 +461,6 @@ struct r5conf {
*/
atomic_t active_stripes;
struct list_head inactive_list;
- struct llist_head released_stripes;
wait_queue_head_t wait_for_stripe;
wait_queue_head_t wait_for_overlap;
int inactive_blocked; /* release of inactive stripes blocked,
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