On 8/16/22 8:58 AM, NeilBrown wrote:
On Mon, 15 Aug 2022, Guoqing Jiang wrote:
Hi Neil,
Sorry for later reply since I was on vacation last week.
On 8/12/22 10:16 AM, NeilBrown wrote:
[[ I noticed the e151 patch recently which seems to admit that it broke
something. So I looked into it and came up with this.
I just noticed it ...
It seems to make sense, but I'm not in a position to test it.
Guoqing: does it look OK to you?
- NeilBrown
]]
As described in Commit: 48df498daf62 ("md: move bitmap_destroy to the
beginning of __md_stop") md_cluster_stop() needs to run before the
mdddev->thread is stopped.
The change to make this happen was reverted in Commit: e151db8ecfb0
("md-raid: destroy the bitmap after destroying the thread") due to
problems it caused.
To restore correct behaviour, make md_cluster_stop() reentrant and
explicitly call it at the start of __md_stop(), after first calling
md_bitmap_wait_behind_writes().
Fixes: e151db8ecfb0 ("md-raid: destroy the bitmap after destroying the thread")
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/md-cluster.c | 1 +
drivers/md/md.c | 3 +++
2 files changed, 4 insertions(+)
diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
index 742b2349fea3..37bf0aa4ed71 100644
--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -1009,6 +1009,7 @@ static int leave(struct mddev *mddev)
test_bit(MD_CLOSING, &mddev->flags)))
resync_bitmap(mddev);
+ mddev->cluster_info = NULL;
The above makes sense.
Thanks.
set_bit(MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD, &cinfo->state);
md_unregister_thread(&cinfo->recovery_thread);
md_unregister_thread(&cinfo->recv_thread);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index afaf36b2f6ab..a57b2dff64dd 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6238,6 +6238,9 @@ static void mddev_detach(struct mddev *mddev)
static void __md_stop(struct mddev *mddev)
{
struct md_personality *pers = mddev->pers;
+
+ md_bitmap_wait_behind_writes(mddev);
+ md_cluster_stop(mddev);
mddev_detach(mddev);
/* Ensure ->event_work is done */
if (mddev->event_work.func)
The md_bitmap_destroy is called in __md_stop with or without e151db8ecfb0,
and it already invokes md_bitmap_wait_behind_writes and md_cluster_stop by
md_bitmap_free. So the above is sort of redundant to me.
The point is that md_cluster_stop() needs to run before mddev_detach()
shuts down the thread. If we don't call all of md_bitmap_destroy()
before mddev_detach() we need to at least run md_cluster_stop(), and I
think we need to run md_bitmap_wait_behind_writes() before that.
For the issue described in e151db8ecfb, looks like raid1d was running after
__md_stop, I am wondering if dm-raid should stop write first just like
normal md-raid.
That looks like a really good idea, that should make it safe to move
md_bitmap_destroy() back before mddev_detach().
Would you like to post a patch to make those two changes, and include
Mikulas Patocka, or should I?
NP, will send it later, thanks for your review.
BRs,
Guoqing
