[PATCH v9] nvme-fabrics: reject I/O to offline device
Victor Gladkov
Victor.Gladkov at kioxia.com
Tue Sep 29 11:27:38 EDT 2020
Commands get stuck while Host NVMe-oF controller is in reconnect state.
NVMe controller enters into reconnect state when it loses connection with the
target. It tries to reconnect every 10 seconds
(default) until successful reconnection or until reconnect time-out is reached.
The default reconnect time out is 10 minutes.
Applications are expecting commands to complete with success or error within
a certain timeout (30 seconds by default). The NVMe host is enforcing that
timeout while it is connected, never the less, during reconnection, the timeout
is not enforced and commands may get stuck for a long period or even forever.
To fix this long delay due to the default timeout we introduce new session
parameter "fast_io_fail_tmo". The timeout is measured in seconds from the
controller reconnect, any command beyond that timeout is rejected. The new
parameter value may be passed during 'connect'.
The default value of -1 means no timeout (similar to current behavior).
We add a new controller NVME_CTRL_FAILFAST_EXPIRED and respective
delayed work that updates the NVME_CTRL_FAILFAST_EXPIRED flag.
When the controller is entering the CONNECTING state, we schedule the
delayed_work based on failfast timeout value. If the transition is out of
CONNECTING, terminate delayed work item and ensure failfast_expired is
false. If delayed work item expires then set "NVME_CTRL_FAILFAST_EXPIRED"
flag to true.
We also update nvmf_fail_nonready_command() and
nvme_available_path() functions with check the
"NVME_CTRL_FAILFAST_EXPIRED" controller flag.
For multipath (function nvme_available_path()):
The path will not be considered available if
"NVME_CTRL_FAILFAST_EXPIRED" controller flag is set
and the controller in NVME_CTRL_CONNECTING state.
This prevents commands from getting stuck
when available paths have tried to reconnect for too long.
Signed-off-by: Victor Gladkov <victor.gladkov at kioxia.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
Reviewed-by: Hannes Reinecke <hare at suse.de>
---
Changes from V8:
1. Added multipath behavior description as requested by Sagi Grimberg
(Fri Sep 18 16:38:58 EDT 2020)
Changes from V7:
1. Expanded the patch description as requested by James Smart
(Thu Aug 13 11:00:25 EDT 2020)
Changes from V6:
1. Changed according to Hannes Reinecke review:
in nvme_start_failfast_work() and nvme_stop_failfast_work() procedures.
Changes from V5:
1. Drop the "off" string option for fast_io_fail_tmo.
Changes from V4:
1. Remove subsysnqn from dev_info just keep "failfast expired"
in nvme_failfast_work().
2. Remove excess lock in nvme_failfast_work().
3. Change "timeout disabled" value to -1, '0' is to fail I/O right away now.
4. Add "off" string for fast_io_fail_tmo option as a -1 equivalent.
Changes from V3:
1. BUG_FIX: Fix a bug in nvme_start_failfast_work() amd
nvme_stop_failfast_work() when accessing ctrl->opts as it will fail
for PCIe transport when is called nvme_change_ctrl_state()
from nvme_reset_work(), since we don't set the ctrl->opts for
PCIe transport.
2. Line wrap in nvme_start_failfast_work(), nvme_parse_option() and
for macro NVMF_ALLOWED_OPTS definition.
3. Just like all the state change code add a switch for newly
added state handling outside of the state machine in
nvme_state_change().
4. nvme_available_path() add /* fallthru */ after if..break inside
switch which is under list_for_each_entry_rcu().
5. Align newly added member nvmf_ctrl_options fast_io_fail_tmp.
6. Fix the tabs before if in nvme_available_path() and line wrap
for the same.
7. In nvme_failfast_work() use state != NVME_CTRL_CONNECTING
instead of == to get rid of the parentheses and avoid char > 80.
8. Get rid of the ";" at the end of the comment for @fast_io_fail_tmp.
9. Change the commit log style to match the one we have in the NVMe
repo.
Changes from V2:
1. Several coding style and small fixes.
2. Fix the comment for NVMF_DEF_FAIL_FAST_TMO.
3. Don't call functionality from the state machine.
4. Rename fast_fail_tmo -> fast_io_fail_tmo to match SCSI
semantics.
Changes from V1:
1. Add a new session parameter called "fast_fail_tmo". The timeout
is measured in seconds from the controller reconnect, any command
beyond that timeout is rejected. The new parameter value may be
passed during 'connect', and its default value is 30 seconds.
A value of 0 means no timeout (similar to current behavior).
2. Add a controller flag of "failfast_expired".
3. Add dedicated delayed_work that update the "failfast_expired"
controller flag.
4. When entering CONNECTING, schedule the delayed_work based on
failfast timeout value. If transition out of CONNECTING, terminate
delayed work item and ensure failfast_expired is false.
If delayed work item expires: set "failfast_expired" flag to true.
5. Update nvmf_fail_nonready_command() with check the
"failfast_expired" controller flag.
---
drivers/nvme/host/core.c | 49
++++++++++++++++++++++++++++++++++++++++++-
drivers/nvme/host/fabrics.c | 25 +++++++++++++++++++---
drivers/nvme/host/fabrics.h | 5 +++++
drivers/nvme/host/multipath.c | 5 ++++-
drivers/nvme/host/nvme.h | 3 +++
5 files changed, 82 insertions(+), 5 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index
f3c037f..ca990bb 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -137,6 +137,37 @@ int nvme_try_sched_reset(struct nvme_ctrl *ctrl) }
EXPORT_SYMBOL_GPL(nvme_try_sched_reset);
+static void nvme_failfast_work(struct work_struct *work) {
+ struct nvme_ctrl *ctrl = container_of(to_delayed_work(work),
+ struct nvme_ctrl, failfast_work);
+
+ if (ctrl->state != NVME_CTRL_CONNECTING)
+ return;
+
+ set_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags);
+ dev_info(ctrl->device, "failfast expired\n");
+ nvme_kick_requeue_lists(ctrl);
+}
+
+static inline void nvme_start_failfast_work(struct nvme_ctrl *ctrl) {
+ if (!ctrl->opts || ctrl->opts->fast_io_fail_tmo == -1)
+ return;
+
+ schedule_delayed_work(&ctrl->failfast_work,
+ ctrl->opts->fast_io_fail_tmo * HZ); }
+
+static inline void nvme_stop_failfast_work(struct nvme_ctrl *ctrl) {
+ if (!ctrl->opts)
+ return;
+
+ cancel_delayed_work_sync(&ctrl->failfast_work);
+ clear_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags); }
+
int nvme_reset_ctrl(struct nvme_ctrl *ctrl) {
if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING)) @@ -387,8
+418,21 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
}
spin_unlock_irqrestore(&ctrl->lock, flags);
- if (changed && ctrl->state == NVME_CTRL_LIVE)
+ if (changed) {
+ switch (ctrl->state) {
+ case NVME_CTRL_LIVE:
+ if (old_state == NVME_CTRL_CONNECTING)
+ nvme_stop_failfast_work(ctrl);
nvme_kick_requeue_lists(ctrl);
+ break;
+ case NVME_CTRL_CONNECTING:
+ if (old_state == NVME_CTRL_RESETTING)
+ nvme_start_failfast_work(ctrl);
+ break;
+ default:
+ break;
+ }
+ }
return changed;
}
EXPORT_SYMBOL_GPL(nvme_change_ctrl_state);
@@ -4045,6 +4089,7 @@ void nvme_stop_ctrl(struct nvme_ctrl *ctrl) {
nvme_mpath_stop(ctrl);
nvme_stop_keep_alive(ctrl);
+ nvme_stop_failfast_work(ctrl);
flush_work(&ctrl->async_event_work);
cancel_work_sync(&ctrl->fw_act_work);
}
@@ -4111,6 +4156,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct
device *dev,
int ret;
ctrl->state = NVME_CTRL_NEW;
+ clear_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags);
spin_lock_init(&ctrl->lock);
mutex_init(&ctrl->scan_lock);
INIT_LIST_HEAD(&ctrl->namespaces);
@@ -4125,6 +4171,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct
device *dev,
init_waitqueue_head(&ctrl->state_wq);
INIT_DELAYED_WORK(&ctrl->ka_work, nvme_keep_alive_work);
+ INIT_DELAYED_WORK(&ctrl->failfast_work, nvme_failfast_work);
memset(&ctrl->ka_cmd, 0, sizeof(ctrl->ka_cmd));
ctrl->ka_cmd.common.opcode = nvme_admin_keep_alive;
diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c index
2a6c819..4afe173 100644
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -549,6 +549,7 @@ blk_status_t nvmf_fail_nonready_command(struct
nvme_ctrl *ctrl, {
if (ctrl->state != NVME_CTRL_DELETING &&
ctrl->state != NVME_CTRL_DEAD &&
+ !test_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags) &&
!blk_noretry_request(rq) && !(rq->cmd_flags & REQ_NVME_MPATH))
return BLK_STS_RESOURCE;
@@ -612,6 +613,7 @@ bool __nvmf_check_ready(struct nvme_ctrl *ctrl,
struct request *rq,
{ NVMF_OPT_NR_WRITE_QUEUES, "nr_write_queues=%d" },
{ NVMF_OPT_NR_POLL_QUEUES, "nr_poll_queues=%d" },
{ NVMF_OPT_TOS, "tos=%d" },
+ { NVMF_OPT_FAIL_FAST_TMO, "fast_io_fail_tmo=%d" },
{ NVMF_OPT_ERR, NULL }
};
@@ -631,6 +633,7 @@ static int nvmf_parse_options(struct
nvmf_ctrl_options *opts,
opts->reconnect_delay = NVMF_DEF_RECONNECT_DELAY;
opts->kato = NVME_DEFAULT_KATO;
opts->duplicate_connect = false;
+ opts->fast_io_fail_tmo = NVMF_DEF_FAIL_FAST_TMO;
opts->hdr_digest = false;
opts->data_digest = false;
opts->tos = -1; /* < 0 == use transport default */ @@ -751,6 +754,17
@@ static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
pr_warn("ctrl_loss_tmo < 0 will reconnect
forever\n");
ctrl_loss_tmo = token;
break;
+ case NVMF_OPT_FAIL_FAST_TMO:
+ if (match_int(args, &token)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (token >= 0)
+ pr_warn("I/O will fail on reconnect controller after"
+ " %d sec\n", token);
+ opts->fast_io_fail_tmo = token;
+ break;
case NVMF_OPT_HOSTNQN:
if (opts->host) {
pr_err("hostnqn already user-assigned: %s\n", @@ -
881,11 +895,16 @@ static int nvmf_parse_options(struct nvmf_ctrl_options
*opts,
opts->nr_poll_queues = 0;
opts->duplicate_connect = true;
}
- if (ctrl_loss_tmo < 0)
+ if (ctrl_loss_tmo < 0) {
opts->max_reconnects = -1;
- else
+ } else {
opts->max_reconnects = DIV_ROUND_UP(ctrl_loss_tmo,
opts->reconnect_delay);
+ if (ctrl_loss_tmo < opts->fast_io_fail_tmo)
+ pr_warn("failfast tmo (%d) larger than controller "
+ "loss tmo (%d)\n",
+ opts->fast_io_fail_tmo, ctrl_loss_tmo);
+ }
if (!opts->host) {
kref_get(&nvmf_default_host->ref);
@@ -985,7 +1004,7 @@ void nvmf_free_options(struct nvmf_ctrl_options
*opts)
#define NVMF_ALLOWED_OPTS (NVMF_OPT_QUEUE_SIZE |
NVMF_OPT_NR_IO_QUEUES | \
NVMF_OPT_KATO | NVMF_OPT_HOSTNQN | \
NVMF_OPT_HOST_ID | NVMF_OPT_DUP_CONNECT
|\
- NVMF_OPT_DISABLE_SQFLOW)
+ NVMF_OPT_DISABLE_SQFLOW |
NVMF_OPT_FAIL_FAST_TMO)
static struct nvme_ctrl *
nvmf_create_ctrl(struct device *dev, const char *buf) diff --git
a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h index
a0ec40a..05a1158 100644
--- a/drivers/nvme/host/fabrics.h
+++ b/drivers/nvme/host/fabrics.h
@@ -15,6 +15,8 @@
#define NVMF_DEF_RECONNECT_DELAY 10
/* default to 600 seconds of reconnect attempts before giving up */
#define NVMF_DEF_CTRL_LOSS_TMO 600
+/* default is -1: the fail fast mechanism is disable */
+#define NVMF_DEF_FAIL_FAST_TMO -1
/*
* Define a host as seen by the target. We allocate one at boot, but also @@ -
56,6 +58,7 @@ enum {
NVMF_OPT_NR_WRITE_QUEUES = 1 << 17,
NVMF_OPT_NR_POLL_QUEUES = 1 << 18,
NVMF_OPT_TOS = 1 << 19,
+ NVMF_OPT_FAIL_FAST_TMO = 1 << 20,
};
/**
@@ -89,6 +92,7 @@ enum {
* @nr_write_queues: number of queues for write I/O
* @nr_poll_queues: number of queues for polling I/O
* @tos: type of service
+ * @fast_io_fail_tmo: Fast I/O fail timeout in seconds
*/
struct nvmf_ctrl_options {
unsigned mask;
@@ -111,6 +115,7 @@ struct nvmf_ctrl_options {
unsigned int nr_write_queues;
unsigned int nr_poll_queues;
int tos;
+ int fast_io_fail_tmo;
};
/*
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 54603bd..d8b7f45 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -278,9 +278,12 @@ static bool nvme_available_path(struct
nvme_ns_head *head)
list_for_each_entry_rcu(ns, &head->list, siblings) {
switch (ns->ctrl->state) {
+ case NVME_CTRL_CONNECTING:
+ if (test_bit(NVME_CTRL_FAILFAST_EXPIRED,
+ &ns->ctrl->flags))
+ break;
case NVME_CTRL_LIVE:
case NVME_CTRL_RESETTING:
- case NVME_CTRL_CONNECTING:
/* fallthru */
return true;
default:
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index
2e04a36..9112886 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -256,6 +256,7 @@ struct nvme_ctrl {
struct work_struct scan_work;
struct work_struct async_event_work;
struct delayed_work ka_work;
+ struct delayed_work failfast_work;
struct nvme_command ka_cmd;
struct work_struct fw_act_work;
unsigned long events;
@@ -290,6 +291,8 @@ struct nvme_ctrl {
u16 icdoff;
u16 maxcmd;
int nr_reconnects;
+ unsigned long flags;
+#define NVME_CTRL_FAILFAST_EXPIRED 0
struct nvmf_ctrl_options *opts;
struct page *discard_page;
--
1.8.3.1
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