* [PATCH 0/2] nvme: delete disk after last connection
@ 2021-03-31 14:53 Hannes Reinecke
2021-03-31 14:53 ` [PATCH 1/2] nvme-mpath: " Hannes Reinecke
2021-03-31 14:53 ` [PATCH 2/2] nvme: do not detach nshead when a namespace is removed Hannes Reinecke
0 siblings, 2 replies; 6+ messages in thread
From: Hannes Reinecke @ 2021-03-31 14:53 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: Sagi Grimberg, Keith Busch, linux-nvme, Hannes Reinecke
Hi all,
as there now is a consensus that we should destroy 'struct nshead'
when the last reference is dropped (and not once the last opener is released)
here now is the updated patchset to make it happen.
The first is the original patch from Keith, for correctly dropping the
disk reference.
The second one is for not removing struct nshead from the subsystem
lists once the last path is gone, but rather defer it until the struct
itself is freed.
As usual, comments and reviews are welcome.
Hannes Reinecke (1):
nvme: do not detach nshead when a namespace is removed
Keith Busch (1):
nvme-mpath: delete disk after last connection
drivers/nvme/host/core.c | 13 ++++++++-----
drivers/nvme/host/multipath.c | 1 -
drivers/nvme/host/nvme.h | 2 +-
3 files changed, 9 insertions(+), 7 deletions(-)
--
2.29.2
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/2] nvme-mpath: delete disk after last connection
2021-03-31 14:53 [PATCH 0/2] nvme: delete disk after last connection Hannes Reinecke
@ 2021-03-31 14:53 ` Hannes Reinecke
2021-03-31 23:40 ` Sagi Grimberg
2021-04-01 8:25 ` Daniel Wagner
2021-03-31 14:53 ` [PATCH 2/2] nvme: do not detach nshead when a namespace is removed Hannes Reinecke
1 sibling, 2 replies; 6+ messages in thread
From: Hannes Reinecke @ 2021-03-31 14:53 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Sagi Grimberg, Keith Busch, linux-nvme, Keith Busch,
Hannes Reinecke
From: Keith Busch <kbusch@kernel.org>
The multipath code currently deletes the disk only after all references
to it are dropped rather than when the last path to that disk is lost.
This has been reported to cause problems with some usage, like MD RAID.
Delete the disk when the last path is gone. This is the same behavior we
currently have with non-multipathed nvme devices.
The following is just a simple example that demonstrates what is currently
observed using a simple nvme loop back (loop setup file not shown):
# nvmetcli restore loop.json
[ 31.156452] nvmet: adding nsid 1 to subsystem testnqn1
[ 31.159140] nvmet: adding nsid 1 to subsystem testnqn2
# nvme connect -t loop -n testnqn1 -q hostnqn
[ 36.866302] nvmet: creating controller 1 for subsystem testnqn1 for NQN hostnqn.
[ 36.872926] nvme nvme3: new ctrl: "testnqn1"
# nvme connect -t loop -n testnqn1 -q hostnqn
[ 38.227186] nvmet: creating controller 2 for subsystem testnqn1 for NQN hostnqn.
[ 38.234450] nvme nvme4: new ctrl: "testnqn1"
# nvme connect -t loop -n testnqn2 -q hostnqn
[ 43.902761] nvmet: creating controller 3 for subsystem testnqn2 for NQN hostnqn.
[ 43.907401] nvme nvme5: new ctrl: "testnqn2"
# nvme connect -t loop -n testnqn2 -q hostnqn
[ 44.627689] nvmet: creating controller 4 for subsystem testnqn2 for NQN hostnqn.
[ 44.641773] nvme nvme6: new ctrl: "testnqn2"
# mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/nvme3n1 /dev/nvme5n1
[ 53.497038] md/raid1:md0: active with 2 out of 2 mirrors
[ 53.501717] md0: detected capacity change from 0 to 66060288
# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 nvme5n1[1] nvme3n1[0]
64512 blocks super 1.2 [2/2] [UU]
Now delete all paths to one of the namespaces:
# echo 1 > /sys/class/nvme/nvme3/delete_controller
# echo 1 > /sys/class/nvme/nvme4/delete_controller
We have no path, but mdstat says:
# cat /proc/mdstat
Personalities : [raid1]
md0 : active (auto-read-only) raid1 nvme5n1[1]
64512 blocks super 1.2 [2/1] [_U]
And this is reported to cause a problem.
With the proposed patch, the following messages appear:
[ 227.516807] md/raid1:md0: Disk failure on nvme3n1, disabling device.
[ 227.516807] md/raid1:md0: Operation continuing on 1 devices.
And mdstat shows only the viable members:
# cat /proc/mdstat
Personalities : [raid1]
md0 : active (auto-read-only) raid1 nvme5n1[1]
64512 blocks super 1.2 [2/1] [_U]
Reported-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/nvme/host/core.c | 5 ++++-
drivers/nvme/host/multipath.c | 1 -
drivers/nvme/host/nvme.h | 2 +-
3 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 40215a0246e4..ee898c8da786 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -542,7 +542,10 @@ static void nvme_free_ns_head(struct kref *ref)
struct nvme_ns_head *head =
container_of(ref, struct nvme_ns_head, ref);
- nvme_mpath_remove_disk(head);
+#ifdef CONFIG_NVME_MULTIPATH
+ if (head->disk)
+ put_disk(head->disk);
+#endif
ida_simple_remove(&head->subsys->ns_ida, head->instance);
cleanup_srcu_struct(&head->srcu);
nvme_put_subsystem(head->subsys);
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index a1d476e1ac02..adea060d1470 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -702,7 +702,6 @@ void nvme_mpath_remove_disk(struct nvme_ns_head *head)
*/
head->disk->queue = NULL;
}
- put_disk(head->disk);
}
int nvme_mpath_init(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index b0863c59fac4..6b8992774998 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -680,7 +680,7 @@ static inline void nvme_mpath_check_last_path(struct nvme_ns *ns)
struct nvme_ns_head *head = ns->head;
if (head->disk && list_empty(&head->list))
- kblockd_schedule_work(&head->requeue_work);
+ nvme_mpath_remove_disk(head);
}
static inline void nvme_trace_bio_complete(struct request *req)
--
2.29.2
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^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 1/2] nvme-mpath: delete disk after last connection
2021-03-31 14:53 ` [PATCH 1/2] nvme-mpath: " Hannes Reinecke
@ 2021-03-31 23:40 ` Sagi Grimberg
2021-04-01 8:25 ` Daniel Wagner
1 sibling, 0 replies; 6+ messages in thread
From: Sagi Grimberg @ 2021-03-31 23:40 UTC (permalink / raw)
To: Hannes Reinecke, Christoph Hellwig; +Cc: Keith Busch, linux-nvme, Keith Busch
On 3/31/21 7:53 AM, Hannes Reinecke wrote:
> From: Keith Busch <kbusch@kernel.org>
>
> The multipath code currently deletes the disk only after all references
> to it are dropped rather than when the last path to that disk is lost.
> This has been reported to cause problems with some usage, like MD RAID.
>
> Delete the disk when the last path is gone. This is the same behavior we
> currently have with non-multipathed nvme devices.
>
> The following is just a simple example that demonstrates what is currently
> observed using a simple nvme loop back (loop setup file not shown):
>
> # nvmetcli restore loop.json
> [ 31.156452] nvmet: adding nsid 1 to subsystem testnqn1
> [ 31.159140] nvmet: adding nsid 1 to subsystem testnqn2
>
> # nvme connect -t loop -n testnqn1 -q hostnqn
> [ 36.866302] nvmet: creating controller 1 for subsystem testnqn1 for NQN hostnqn.
> [ 36.872926] nvme nvme3: new ctrl: "testnqn1"
>
> # nvme connect -t loop -n testnqn1 -q hostnqn
> [ 38.227186] nvmet: creating controller 2 for subsystem testnqn1 for NQN hostnqn.
> [ 38.234450] nvme nvme4: new ctrl: "testnqn1"
>
> # nvme connect -t loop -n testnqn2 -q hostnqn
> [ 43.902761] nvmet: creating controller 3 for subsystem testnqn2 for NQN hostnqn.
> [ 43.907401] nvme nvme5: new ctrl: "testnqn2"
>
> # nvme connect -t loop -n testnqn2 -q hostnqn
> [ 44.627689] nvmet: creating controller 4 for subsystem testnqn2 for NQN hostnqn.
> [ 44.641773] nvme nvme6: new ctrl: "testnqn2"
>
> # mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/nvme3n1 /dev/nvme5n1
> [ 53.497038] md/raid1:md0: active with 2 out of 2 mirrors
> [ 53.501717] md0: detected capacity change from 0 to 66060288
>
> # cat /proc/mdstat
> Personalities : [raid1]
> md0 : active raid1 nvme5n1[1] nvme3n1[0]
> 64512 blocks super 1.2 [2/2] [UU]
>
> Now delete all paths to one of the namespaces:
>
> # echo 1 > /sys/class/nvme/nvme3/delete_controller
> # echo 1 > /sys/class/nvme/nvme4/delete_controller
>
> We have no path, but mdstat says:
>
> # cat /proc/mdstat
> Personalities : [raid1]
> md0 : active (auto-read-only) raid1 nvme5n1[1]
> 64512 blocks super 1.2 [2/1] [_U]
>
> And this is reported to cause a problem.
>
> With the proposed patch, the following messages appear:
>
> [ 227.516807] md/raid1:md0: Disk failure on nvme3n1, disabling device.
> [ 227.516807] md/raid1:md0: Operation continuing on 1 devices.
>
> And mdstat shows only the viable members:
>
> # cat /proc/mdstat
> Personalities : [raid1]
> md0 : active (auto-read-only) raid1 nvme5n1[1]
> 64512 blocks super 1.2 [2/1] [_U]
>
> Reported-by: Hannes Reinecke <hare@suse.de>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
> drivers/nvme/host/core.c | 5 ++++-
> drivers/nvme/host/multipath.c | 1 -
> drivers/nvme/host/nvme.h | 2 +-
> 3 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 40215a0246e4..ee898c8da786 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -542,7 +542,10 @@ static void nvme_free_ns_head(struct kref *ref)
> struct nvme_ns_head *head =
> container_of(ref, struct nvme_ns_head, ref);
>
> - nvme_mpath_remove_disk(head);
> +#ifdef CONFIG_NVME_MULTIPATH
> + if (head->disk)
> + put_disk(head->disk);
> +#endif
Hannes, maybe make that nvme_mpath_put_disk(head) and place an empty
stab in nvme.h like we do for other mpath variants?
Other than that, patch looks good, so you can add to the respin
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] nvme-mpath: delete disk after last connection
2021-03-31 14:53 ` [PATCH 1/2] nvme-mpath: " Hannes Reinecke
2021-03-31 23:40 ` Sagi Grimberg
@ 2021-04-01 8:25 ` Daniel Wagner
1 sibling, 0 replies; 6+ messages in thread
From: Daniel Wagner @ 2021-04-01 8:25 UTC (permalink / raw)
To: Hannes Reinecke
Cc: Christoph Hellwig, Sagi Grimberg, Keith Busch, linux-nvme,
Keith Busch
On Wed, Mar 31, 2021 at 04:53:50PM +0200, Hannes Reinecke wrote:
> Reported-by: Hannes Reinecke <hare@suse.de>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 2/2] nvme: do not detach nshead when a namespace is removed
2021-03-31 14:53 [PATCH 0/2] nvme: delete disk after last connection Hannes Reinecke
2021-03-31 14:53 ` [PATCH 1/2] nvme-mpath: " Hannes Reinecke
@ 2021-03-31 14:53 ` Hannes Reinecke
2021-03-31 23:49 ` Sagi Grimberg
1 sibling, 1 reply; 6+ messages in thread
From: Hannes Reinecke @ 2021-03-31 14:53 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: Sagi Grimberg, Keith Busch, linux-nvme, Hannes Reinecke
'struct nshead' and 'struct ns' have different lifetimes; the nshead
can (and occasionally will) stay around even if no namespaces are
connected, as it will only be finally removed once the last
reference is gone.
But while it is in this state we should still be able to access
it during lookup; a nshead with no controllers is perfectly valid
(at least for fabrics), and the namespace has no business with
removing the nshead from the subsystem lists.
This patch fixes the situation by only removing the nshead from the
subsystem list once it's being finally removed.
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/nvme/host/core.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ee898c8da786..05fecbd33fa7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -542,6 +542,10 @@ static void nvme_free_ns_head(struct kref *ref)
struct nvme_ns_head *head =
container_of(ref, struct nvme_ns_head, ref);
+ mutex_lock(&head->subsys->lock);
+ list_del_init(&head->entry);
+ mutex_unlock(&head->subsys->lock);
+
#ifdef CONFIG_NVME_MULTIPATH
if (head->disk)
put_disk(head->disk);
@@ -3993,8 +3997,6 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
out_unlink_ns:
mutex_lock(&ctrl->subsys->lock);
list_del_rcu(&ns->siblings);
- if (list_empty(&ns->head->list))
- list_del_init(&ns->head->entry);
mutex_unlock(&ctrl->subsys->lock);
nvme_put_ns_head(ns->head);
out_free_queue:
@@ -4015,8 +4017,6 @@ static void nvme_ns_remove(struct nvme_ns *ns)
mutex_lock(&ns->ctrl->subsys->lock);
list_del_rcu(&ns->siblings);
- if (list_empty(&ns->head->list))
- list_del_init(&ns->head->entry);
mutex_unlock(&ns->ctrl->subsys->lock);
synchronize_rcu(); /* guarantee not available in head->list */
--
2.29.2
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] nvme: do not detach nshead when a namespace is removed
2021-03-31 14:53 ` [PATCH 2/2] nvme: do not detach nshead when a namespace is removed Hannes Reinecke
@ 2021-03-31 23:49 ` Sagi Grimberg
0 siblings, 0 replies; 6+ messages in thread
From: Sagi Grimberg @ 2021-03-31 23:49 UTC (permalink / raw)
To: Hannes Reinecke, Christoph Hellwig; +Cc: Keith Busch, linux-nvme
> 'struct nshead' and 'struct ns' have different lifetimes; the nshead
> can (and occasionally will) stay around even if no namespaces are
> connected, as it will only be finally removed once the last
> reference is gone.
> But while it is in this state we should still be able to access
> it during lookup; a nshead with no controllers is perfectly valid
> (at least for fabrics), and the namespace has no business with
> removing the nshead from the subsystem lists.
>
> This patch fixes the situation by only removing the nshead from the
> subsystem list once it's being finally removed.
Hannes, please explain what is the bug you are solving here.
I actually think that the nshead should be removed from the
list as soon as the last the head->list is empty.
What if for example a new ns is allocated on the subsystem
and the nsid (which was already deleted) is reused, it will now
be rejected when we match against existing nsheads which will
contain this stale nshead that happens to have an open reference.
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^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-04-01 8:25 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2021-03-31 14:53 [PATCH 0/2] nvme: delete disk after last connection Hannes Reinecke
2021-03-31 14:53 ` [PATCH 1/2] nvme-mpath: " Hannes Reinecke
2021-03-31 23:40 ` Sagi Grimberg
2021-04-01 8:25 ` Daniel Wagner
2021-03-31 14:53 ` [PATCH 2/2] nvme: do not detach nshead when a namespace is removed Hannes Reinecke
2021-03-31 23:49 ` Sagi Grimberg
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