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nvmet: Fix possible infinite loop triggered on hot namespace removal

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When removing a namespace we delete it from the subsystem namespaces
list with list_del_init which allows us to know if it is enabled or
not.

The problem is that list_del_init initialize the list next and does
not respect the RCU list-traversal we do on the IO path for locating
a namespace. Instead we need to use list_del_rcu which is allowed to
run concurrently with the _rcu list-traversal primitives (keeps list
next intact) and guarantees concurrent nvmet_find_naespace forward
progress.

By changing that, we cannot rely on ns->dev_link for knowing if the
namspace is enabled, so add enabled indicator entry to nvmet_ns for
that.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Solganik Alexander <sashas@lightbitslabs.com>
Cc: <stable@vger.kernel.org> # v4.8+
This commit is contained in:
Solganik Alexander
2016-10-30 10:35:15 +02:00
committed by Sagi Grimberg
parent f3116d8f1e
commit e4fcf07cca
3 changed files with 12 additions and 14 deletions
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6
drivers/nvme/target/nvmet.h
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@@ -47,6 +47,7 @@ struct nvmet_ns {
loff_t size;
u8 nguid[16];
bool enabled;
struct nvmet_subsys *subsys;
const char *device_path;
@@ -61,11 +62,6 @@ static inline struct nvmet_ns *to_nvmet_ns(struct config_item *item)
return container_of(to_config_group(item), struct nvmet_ns, group);
}
static inline bool nvmet_ns_enabled(struct nvmet_ns *ns)
{
return !list_empty_careful(&ns->dev_link);
}
struct nvmet_cq {
u16 qid;
u16 size;