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nvmet: defer setting ns->enabled to false in nvmet_ns_disable()

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nvmet_ns_disable() currently clears ns->enabled before draining
in-flight I/O references. This allows namespace configuration to be
changed while existing I/O requests can still hold a reference to the
namespace.

This can race with configuration of namespace attributes such as the
device path, UUID, NGUID etc. These attributes can be accessed by I/O
requests without holding subsys->lock and must not be modified while
such requests are still using the namespace.

In nvmet_ns_disable(), keep ns->enabled set while existing namespace
references are being drained, so namespace configuration remains blocked
until all in-flight I/O has completed. Set ns->enabled to false only
after the namespace references have been drained and the namespace
device has been disabled.

Introduce the NVMET_NS_IO_LIVE flag, which is set after the namespace
is successfully enabled in nvmet_ns_enable(). When nvmet_ns_disable()
starts, clear NVMET_NS_IO_LIVE so that the I/O path stops admitting new
I/O once the flag is cleared. Using test_and_clear_bit() in
nvmet_ns_disable() also prevents concurrent callers from starting a
second disable operation.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
This commit is contained in:
Nilay Shroff 2026-09-18 21:57:30 +05:30 committed by Keith Busch
parent 5211fed41d
commit 42b0f5196d
2 changed files with 10 additions and 6 deletions
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14
drivers/nvme/target/core.c
View File

@ -448,7 +448,8 @@ u16 nvmet_req_find_ns(struct nvmet_req *req)
struct nvmet_subsys *subsys = nvmet_req_subsys(req);
req->ns = xa_load(&subsys->namespaces, nsid);
if (unlikely(!req->ns || !req->ns->enabled)) {
if (unlikely(!req->ns) ||
!test_bit(NVMET_NS_IO_LIVE, &req->ns->flags)) {
req->error_loc = offsetof(struct nvme_common_command, nsid);
if (!req->ns) /* ns doesn't exist! */
return NVME_SC_INVALID_NS | NVME_STATUS_DNR;
@ -623,6 +624,7 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
ns->enabled = true;
xa_set_mark(&subsys->namespaces, ns->nsid, NVMET_NS_ENABLED);
nvmet_debugfs_ns_setup(ns);
set_bit(NVMET_NS_IO_LIVE, &ns->flags);
ret = 0;
out_unlock:
mutex_unlock(&subsys->lock);
@ -643,11 +645,11 @@ void nvmet_ns_disable(struct nvmet_ns *ns)
struct nvmet_subsys *subsys = ns->subsys;
struct nvmet_ctrl *ctrl;
mutex_lock(&subsys->lock);
if (!ns->enabled)
goto out_unlock;
if (!test_and_clear_bit(NVMET_NS_IO_LIVE, &ns->flags))
return;
mutex_lock(&subsys->lock);
ns->enabled = false;
xa_clear_mark(&subsys->namespaces, ns->nsid, NVMET_NS_ENABLED);
nvmet_debugfs_ns_free(ns);
@ -675,7 +677,7 @@ void nvmet_ns_disable(struct nvmet_ns *ns)
mutex_lock(&subsys->lock);
nvmet_ns_changed(subsys, ns->nsid);
nvmet_ns_dev_disable(ns);
out_unlock:
ns->enabled = false;
mutex_unlock(&subsys->lock);
}

2
drivers/nvme/target/nvmet.h
View File

@ -112,6 +112,8 @@ struct nvmet_ns {
bool buffered_io;
bool enabled;
#define NVMET_NS_IO_LIVE 0
unsigned long flags;
struct nvmet_subsys *subsys;
const char *device_path;