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Kernel/NVMe: Redesign the tracking of requests in an NVMe Queue

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There was a private variable named m_current_request which was used to
track a single request at a time. This guarantee is given by the block
layer where we wait on each IO. This design will break down in the
driver once the block layer removes that constraint.

Redesign the IO handling in a completely asynchronous way by maintaining
requests up to queue depth. NVMeIO struct is introduced to track an IO
submitted along with other information such whether the IO is still
being processed and an endio callback which will be called during the
end of a request.

A hashmap private variable is created which will key based on the
command id of a request with a value of NVMeIO. endio handler will come
in handy if we are doing a sync request and we want to wake up the wait
queue during the end.

This change also simplified the code by removing some special condition
in submit_sqe function, etc that were marked as FIXME for a long time.
This commit is contained in:
Pankaj Raghav 2023-03-26 23:16:50 +02:00 • committed by Jelle Raaijmakers
parent 3fe7bda021
commit 0096eadf40
6 changed files with 103 additions and 43 deletions
Download patch file Download diff file Expand all files Collapse all files

53
Kernel/Storage/NVMe/NVMeQueue.cpp
View file

@ -26,8 +26,7 @@ ErrorOr<NonnullLockRefPtr<NVMeQueue>> NVMeQueue::try_create(u16 qid, Optional<u8
}
UNMAP_AFTER_INIT NVMeQueue::NVMeQueue(NonnullOwnPtr<Memory::Region> rw_dma_region, Memory::PhysicalPage const& rw_dma_page, u16 qid, u32 q_depth, OwnPtr<Memory::Region> cq_dma_region, Vector<NonnullRefPtr<Memory::PhysicalPage>> cq_dma_page, OwnPtr<Memory::Region> sq_dma_region, Vector<NonnullRefPtr<Memory::PhysicalPage>> sq_dma_page, Memory::TypedMapping<DoorbellRegister volatile> db_regs)
: m_current_request(nullptr)
, m_rw_dma_region(move(rw_dma_region))
: m_rw_dma_region(move(rw_dma_region))
, m_qid(qid)
, m_admin_queue(qid == 0)
, m_qdepth(q_depth)
@ -39,6 +38,7 @@ UNMAP_AFTER_INIT NVMeQueue::NVMeQueue(NonnullOwnPtr<Memory::Region> rw_dma_regio
, m_rw_dma_page(rw_dma_page)
{
m_requests.try_ensure_capacity(q_depth).release_value_but_fixme_should_propagate_errors();
m_sqe_array = { reinterpret_cast<NVMeSubmission*>(m_sq_dma_region->vaddr().as_ptr()), m_qdepth };
m_cqe_array = { reinterpret_cast<NVMeCompletion*>(m_cq_dma_region->vaddr().as_ptr()), m_qdepth };
}
@ -70,15 +70,12 @@ u32 NVMeQueue::process_cq()
status = CQ_STATUS_FIELD(m_cqe_array[m_cq_head].status);
cmdid = m_cqe_array[m_cq_head].command_id;
dbgln_if(NVME_DEBUG, "NVMe: Completion with status {:x} and command identifier {}. CQ_HEAD: {}", status, cmdid, m_cq_head);
// TODO: We don't use AsyncBlockDevice requests for admin queue as it is only applicable for a block device (NVMe namespace)
// But admin commands precedes namespace creation. Unify requests to avoid special conditions
if (m_admin_queue == false) {
// As the block layer calls are now sync (as we wait on each requests),
// everything is operated on a single request similar to BMIDE driver.
if (m_current_request) {
complete_current_request(status);
}
if (!m_requests.contains(cmdid)) {
dmesgln("Bogus cmd id: {}", cmdid);
VERIFY_NOT_REACHED();
}
complete_current_request(cmdid, status);
update_cqe_head();
}
if (nr_of_processed_cqes) {
@ -112,6 +109,14 @@ u16 NVMeQueue::submit_sync_sqe(NVMeSubmission& sub)
u16 cid = get_request_cid();
sub.cmdid = cid;
{
SpinlockLocker req_lock(m_request_lock);
if (m_requests.contains(sub.cmdid) && m_requests.get(sub.cmdid).release_value().used)
VERIFY_NOT_REACHED();
m_requests.set(sub.cmdid, { nullptr, true, nullptr });
}
submit_sqe(sub);
do {
int index;
@ -132,9 +137,6 @@ u16 NVMeQueue::submit_sync_sqe(NVMeSubmission& sub)
void NVMeQueue::read(AsyncBlockDeviceRequest& request, u16 nsid, u64 index, u32 count)
{
NVMeSubmission sub {};
SpinlockLocker m_lock(m_request_lock);
m_current_request = request;
sub.op = OP_NVME_READ;
sub.rw.nsid = nsid;
sub.rw.slba = AK::convert_between_host_and_little_endian(index);
@ -143,6 +145,13 @@ void NVMeQueue::read(AsyncBlockDeviceRequest& request, u16 nsid, u64 index, u32
sub.rw.data_ptr.prp1 = reinterpret_cast<u64>(AK::convert_between_host_and_little_endian(m_rw_dma_page->paddr().as_ptr()));
sub.cmdid = get_request_cid();
{
SpinlockLocker req_lock(m_request_lock);
if (m_requests.contains(sub.cmdid) && m_requests.get(sub.cmdid).release_value().used)
VERIFY_NOT_REACHED();
m_requests.set(sub.cmdid, { request, true, nullptr });
}
full_memory_barrier();
submit_sqe(sub);
}
@ -150,13 +159,7 @@ void NVMeQueue::read(AsyncBlockDeviceRequest& request, u16 nsid, u64 index, u32
void NVMeQueue::write(AsyncBlockDeviceRequest& request, u16 nsid, u64 index, u32 count)
{
NVMeSubmission sub {};
SpinlockLocker m_lock(m_request_lock);
m_current_request = request;
if (auto result = m_current_request->read_from_buffer(m_current_request->buffer(), m_rw_dma_region->vaddr().as_ptr(), m_current_request->buffer_size()); result.is_error()) {
complete_current_request(AsyncDeviceRequest::MemoryFault);
return;
}
sub.op = OP_NVME_WRITE;
sub.rw.nsid = nsid;
sub.rw.slba = AK::convert_between_host_and_little_endian(index);
@ -165,6 +168,18 @@ void NVMeQueue::write(AsyncBlockDeviceRequest& request, u16 nsid, u64 index, u32
sub.rw.data_ptr.prp1 = reinterpret_cast<u64>(AK::convert_between_host_and_little_endian(m_rw_dma_page->paddr().as_ptr()));
sub.cmdid = get_request_cid();
{
SpinlockLocker req_lock(m_request_lock);
if (m_requests.contains(sub.cmdid) && m_requests.get(sub.cmdid).release_value().used)
VERIFY_NOT_REACHED();
m_requests.set(sub.cmdid, { request, true, nullptr });
}
if (auto result = request.read_from_buffer(request.buffer(), m_rw_dma_region->vaddr().as_ptr(), request.buffer_size()); result.is_error()) {
complete_current_request(sub.cmdid, AsyncDeviceRequest::MemoryFault);
return;
}
full_memory_barrier();
submit_sqe(sub);
}