[PATCH v4 1/2] nvme: Add fault injection feature
Thomas Tai
thomas.tai at oracle.com
Thu Feb 8 10:38:29 PST 2018
Linux's fault injection framework provides a systematic way to support
error injection via debugfs in the /sys/kernel/debug directory. This
patch uses the framework to add error injection to NVMe driver. The
fault injection source code is stored in a separate file and only linked
if CONFIG_FAULT_INJECTION_DEBUG_FS kernel config is selected.
Once the error injection is enabled, NVME_SC_INVALID_OPCODE with no
retry will be injected into the nvme_end_request. Users can change
the default status code and no retry flag via debufs. Following example
shows how to enable and inject an error. For more examples, refer to
Documentation/fault-injection/nvme-fault-injection.txt
How to enable nvme fault injection:
First, enable CONFIG_FAULT_INJECTION_DEBUG_FS kernel config,
recompile the kernel. After booting up the kernel, do the
following.
How to inject an error:
mount /dev/nvme0n1 /mnt
echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
cp a.file /mnt
Expected Result:
cp: cannot stat ‘/mnt/a.file’: Input/output error
Message from dmesg:
FAULT_INJECTION: forcing a failure.
name fault_inject, interval 1, probability 100, space 0, times 1
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc8+ #2
Hardware name: innotek GmbH VirtualBox/VirtualBox,
BIOS VirtualBox 12/01/2006
Call Trace:
<IRQ>
dump_stack+0x5c/0x7d
should_fail+0x148/0x170
nvme_should_fail+0x2f/0x50 [nvme_core]
nvme_process_cq+0xe7/0x1d0 [nvme]
nvme_irq+0x1e/0x40 [nvme]
__handle_irq_event_percpu+0x3a/0x190
handle_irq_event_percpu+0x30/0x70
handle_irq_event+0x36/0x60
handle_fasteoi_irq+0x78/0x120
handle_irq+0xa7/0x130
? tick_irq_enter+0xa8/0xc0
do_IRQ+0x43/0xc0
common_interrupt+0xa2/0xa2
</IRQ>
RIP: 0010:native_safe_halt+0x2/0x10
RSP: 0018:ffffffff82003e90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdd
RAX: ffffffff817a10c0 RBX: ffffffff82012480 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 000000008e38ce64 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82012480
R13: ffffffff82012480 R14: 0000000000000000 R15: 0000000000000000
? __sched_text_end+0x4/0x4
default_idle+0x18/0xf0
do_idle+0x150/0x1d0
cpu_startup_entry+0x6f/0x80
start_kernel+0x4c4/0x4e4
? set_init_arg+0x55/0x55
secondary_startup_64+0xa5/0xb0
print_req_error: I/O error, dev nvme0n1, sector 9240
EXT4-fs error (device nvme0n1): ext4_find_entry:1436:
inode #2: comm cp: reading directory lblock 0
Signed-off-by: Thomas Tai <thomas.tai at oracle.com>
Reviewed-by: Eric Saint-Etienne <eric.saint.etienne at oracle.com>
Signed-off-by: Karl Volz <karl.volz at oracle.com>
Reviewed-by: Keith Busch <keith.busch at intel.com>
---
drivers/nvme/host/Makefile | 1 +
drivers/nvme/host/core.c | 2 +
drivers/nvme/host/fault_inject.c | 79 ++++++++++++++++++++++++++++++++++++++++
drivers/nvme/host/nvme.h | 27 ++++++++++++++
4 files changed, 109 insertions(+)
create mode 100644 drivers/nvme/host/fault_inject.c
diff --git a/drivers/nvme/host/Makefile b/drivers/nvme/host/Makefile
index a25fd43..d38131e 100644
--- a/drivers/nvme/host/Makefile
+++ b/drivers/nvme/host/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_NVME_FC) += nvme-fc.o
nvme-core-y := core.o
nvme-core-$(CONFIG_NVME_MULTIPATH) += multipath.o
nvme-core-$(CONFIG_NVM) += lightnvm.o
+nvme-core-$(CONFIG_FAULT_INJECTION_DEBUG_FS) += fault_inject.o
nvme-y += pci.o
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 839650e..49fa6da 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2951,6 +2951,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
if (new)
nvme_mpath_add_disk(ns->head);
nvme_mpath_add_disk_links(ns);
+ nvme_fault_inject_init(ns);
return;
out_unlink_ns:
mutex_lock(&ctrl->subsys->lock);
@@ -2969,6 +2970,7 @@ static void nvme_ns_remove(struct nvme_ns *ns)
if (test_and_set_bit(NVME_NS_REMOVING, &ns->flags))
return;
+ nvme_fault_inject_fini(ns);
if (ns->disk && ns->disk->flags & GENHD_FL_UP) {
nvme_mpath_remove_disk_links(ns);
sysfs_remove_group(&disk_to_dev(ns->disk)->kobj,
diff --git a/drivers/nvme/host/fault_inject.c b/drivers/nvme/host/fault_inject.c
new file mode 100644
index 0000000..0263226
--- /dev/null
+++ b/drivers/nvme/host/fault_inject.c
@@ -0,0 +1,79 @@
+/*
+ * fault injection support for nvme.
+ *
+ * Copyright (c) 2018, Oracle and/or its affiliates
+ *
+ */
+
+#include <linux/moduleparam.h>
+#include "nvme.h"
+
+static DECLARE_FAULT_ATTR(fail_default_attr);
+/* optional fault injection attributes boot time option:
+ * nvme_core.fail_request=<interval>,<probability>,<space>,<times>
+ */
+static char *fail_request;
+module_param(fail_request, charp, 0000);
+
+void nvme_fault_inject_init(struct nvme_ns *ns)
+{
+ struct dentry *dir, *parent;
+ char *name = ns->disk->disk_name;
+ struct nvme_fault_inject *fault_inj = &ns->fault_inject;
+ struct fault_attr *attr = &fault_inj->attr;
+
+ /* set default fault injection attribute */
+ if (fail_request)
+ setup_fault_attr(&fail_default_attr, fail_request);
+
+ /* create debugfs directory and attribute */
+ parent = debugfs_create_dir(name, NULL);
+ if (!parent) {
+ pr_warn("%s: failed to create debugfs directory\n", name);
+ return;
+ }
+
+ *attr = fail_default_attr;
+ dir = fault_create_debugfs_attr("fault_inject", parent, attr);
+ if (IS_ERR(dir)) {
+ pr_warn("%s: failed to create debugfs attr\n", name);
+ debugfs_remove_recursive(parent);
+ return;
+ }
+ ns->fault_inject.parent = parent;
+
+ /* create debugfs for status code and dont_retry */
+ fault_inj->status = NVME_SC_INVALID_OPCODE;
+ fault_inj->dont_retry = true;
+ debugfs_create_x16("status", 0600, dir, &fault_inj->status);
+ debugfs_create_bool("dont_retry", 0600, dir, &fault_inj->dont_retry);
+}
+
+void nvme_fault_inject_fini(struct nvme_ns *ns)
+{
+ /* remove debugfs directories */
+ debugfs_remove_recursive(ns->fault_inject.parent);
+}
+
+void nvme_should_fail(struct request *req)
+{
+ struct gendisk *disk = req->rq_disk;
+ struct nvme_ns *ns = NULL;
+ u16 status;
+
+ /*
+ * make sure this request is coming from a valid namespace
+ */
+ if (!disk)
+ return;
+
+ ns = disk->private_data;
+ if (ns && should_fail(&ns->fault_inject.attr, 1)) {
+ /* inject status code and DNR bit */
+ status = ns->fault_inject.status;
+ if (ns->fault_inject.dont_retry)
+ status |= NVME_SC_DNR;
+ nvme_req(req)->status = status;
+ }
+}
+EXPORT_SYMBOL_GPL(nvme_should_fail);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index a00eabd..456a7a8 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -21,6 +21,7 @@
#include <linux/blk-mq.h>
#include <linux/lightnvm.h>
#include <linux/sed-opal.h>
+#include <linux/fault-inject.h>
extern unsigned int nvme_io_timeout;
#define NVME_IO_TIMEOUT (nvme_io_timeout * HZ)
@@ -257,6 +258,15 @@ struct nvme_ns_head {
int instance;
};
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+struct nvme_fault_inject {
+ struct fault_attr attr;
+ struct dentry *parent;
+ bool dont_retry; /* DNR, do not retry */
+ u16 status; /* status code */
+};
+#endif
+
struct nvme_ns {
struct list_head list;
@@ -278,6 +288,11 @@ struct nvme_ns {
#define NVME_NS_REMOVING 0
#define NVME_NS_DEAD 1
u16 noiob;
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+ struct nvme_fault_inject fault_inject;
+#endif
+
};
struct nvme_ctrl_ops {
@@ -296,6 +311,16 @@ struct nvme_ctrl_ops {
int (*reinit_request)(void *data, struct request *rq);
};
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+void nvme_fault_inject_init(struct nvme_ns *ns);
+void nvme_fault_inject_fini(struct nvme_ns *ns);
+void nvme_should_fail(struct request *req);
+#else
+static inline void nvme_fault_inject_init(struct nvme_ns *ns) {}
+static inline void nvme_fault_inject_fini(struct nvme_ns *ns) {}
+static inline void nvme_should_fail(struct request *req) {}
+#endif
+
static inline bool nvme_ctrl_ready(struct nvme_ctrl *ctrl)
{
u32 val = 0;
@@ -332,6 +357,8 @@ static inline void nvme_end_request(struct request *req, __le16 status,
rq->status = le16_to_cpu(status) >> 1;
rq->result = result;
+ /* inject error when permitted by fault injection framework */
+ nvme_should_fail(req);
blk_mq_complete_request(req);
}
--
1.8.3.1
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