Re: [RFC 0/1] nvme: Add NVMe LBA Fault Injection

[Keith Busch <kbusch@kernel.org>]

On Thu, Jan 18, 2024 at 09:02:43AM -0800, alan.adamson@oracle.com wrote:
> 
> On 1/17/24 11:24 PM, Christoph Hellwig wrote:
> > On Tue, Jan 16, 2024 at 03:27:27PM -0800, Alan Adamson wrote:
> > > It has been requested that the NVMe fault injector be able to inject faults when accessing
> > > specific Logical Block Addresses (LBA).
> > Curious, but who has requested this?  Because injecting errors really
> > isn't the drivers job.
> 
> 
> It's an application (database) that is requesting it for their error
> handling testing.

Going out on a limb here... This seems so obscure to burden a driver to
synthesize. Could we just give a hook for a bpf override and you can
totally go for whatever scenario you can imagine with a script?

---
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 50818dbcfa1ae..df87a63335aa8 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -381,9 +381,22 @@ static inline void nvme_end_req_zoned(struct request *req)
 	}
 }
 
+#ifdef CONFIG_BPF_KPROBE_OVERRIDE
+static noinline blk_status_t nvme_req_status(struct nvme_request *req)
+{
+	return nvme_error_status(req->status);
+}
+ALLOW_ERROR_INJECTION(nvme_req_status, ERRNO);
+#else
+static inline blk_status_t nvme_req_status(struct nvme_request *req)
+{
+	return nvme_error_status(req->status);
+}
+#endif
+
 static inline void nvme_end_req(struct request *req)
 {
-	blk_status_t status = nvme_error_status(nvme_req(req)->status);
+	blk_status_t status = nvme_req_status(nvme_req(req));
 
 	if (unlikely(nvme_req(req)->status && !(req->rq_flags & RQF_QUIET)))
 		nvme_log_error(req);
--