tcmu: make ring buffer timer configurable

This adds a timer, qfull_time_out, that controls how long a
device will wait for ring buffer space to open before
failing the commands in the queue. It is useful to separate
this timer from the cmd_time_out and default 30 sec one,
because for HA setups cmd_time_out may be disbled and 30
seconds is too long to wait when some OSs like ESX will
timeout commands after as little as 8 - 15 seconds.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 52fc1d4..c6a0c31 100644 (file)
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -142,8 +142,12 @@ struct tcmu_dev {
 
        struct idr commands;
 
-       struct timer_list timeout;
+       struct timer_list cmd_timer;
        unsigned int cmd_time_out;
+
+       struct timer_list qfull_timer;
+       int qfull_time_out;
+
        struct list_head timedout_entry;
 
        spinlock_t nl_cmd_lock;
@@ -741,18 +745,14 @@ static inline size_t tcmu_cmd_get_cmd_size(struct tcmu_cmd *tcmu_cmd,
        return command_size;
 }
 
-static int tcmu_setup_cmd_timer(struct tcmu_cmd *tcmu_cmd)
+static int tcmu_setup_cmd_timer(struct tcmu_cmd *tcmu_cmd, unsigned int tmo,
+                               struct timer_list *timer)
 {
        struct tcmu_dev *udev = tcmu_cmd->tcmu_dev;
-       unsigned long tmo = udev->cmd_time_out;
        int cmd_id;
 
-       /*
-        * If it was on the cmdr queue waiting we do not reset the timer
-        * for requeues and when it is finally sent to userspace.
-        */
        if (tcmu_cmd->cmd_id)
-               return 0;
+               goto setup_timer;
 
        cmd_id = idr_alloc(&udev->commands, tcmu_cmd, 1, USHRT_MAX, GFP_NOWAIT);
        if (cmd_id < 0) {
@@ -761,23 +761,38 @@ static int tcmu_setup_cmd_timer(struct tcmu_cmd *tcmu_cmd)
        }
        tcmu_cmd->cmd_id = cmd_id;
 
-       if (!tmo)
-               tmo = TCMU_TIME_OUT;
-
        pr_debug("allocated cmd %u for dev %s tmo %lu\n", tcmu_cmd->cmd_id,
                 udev->name, tmo / MSEC_PER_SEC);
 
+setup_timer:
+       if (!tmo)
+               return 0;
+
        tcmu_cmd->deadline = round_jiffies_up(jiffies + msecs_to_jiffies(tmo));
-       mod_timer(&udev->timeout, tcmu_cmd->deadline);
+       mod_timer(timer, tcmu_cmd->deadline);
        return 0;
 }
 
 static int add_to_cmdr_queue(struct tcmu_cmd *tcmu_cmd)
 {
        struct tcmu_dev *udev = tcmu_cmd->tcmu_dev;
+       unsigned int tmo;
        int ret;
 
-       ret = tcmu_setup_cmd_timer(tcmu_cmd);
+       /*
+        * For backwards compat if qfull_time_out is not set use
+        * cmd_time_out and if that's not set use the default time out.
+        */
+       if (!udev->qfull_time_out)
+               return -ETIMEDOUT;
+       else if (udev->qfull_time_out > 0)
+               tmo = udev->qfull_time_out;
+       else if (udev->cmd_time_out)
+               tmo = udev->cmd_time_out;
+       else
+               tmo = TCMU_TIME_OUT;
+
+       ret = tcmu_setup_cmd_timer(tcmu_cmd, tmo, &udev->qfull_timer);
        if (ret)
                return ret;
 
@@ -901,7 +916,8 @@ static sense_reason_t queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, int *scsi_err)
        }
        entry->req.iov_bidi_cnt = iov_cnt;
 
-       ret = tcmu_setup_cmd_timer(tcmu_cmd);
+       ret = tcmu_setup_cmd_timer(tcmu_cmd, udev->cmd_time_out,
+                                  &udev->cmd_timer);
        if (ret) {
                tcmu_cmd_free_data(tcmu_cmd, tcmu_cmd->dbi_cnt);
                mutex_unlock(&udev->cmdr_lock);
@@ -1049,14 +1065,19 @@ static unsigned int tcmu_handle_completions(struct tcmu_dev *udev)
                handled++;
        }
 
-       if (mb->cmd_tail == mb->cmd_head && list_empty(&udev->cmdr_queue)) {
-               del_timer(&udev->timeout);
-               /*
-                * not more pending or waiting commands so try to reclaim
-                * blocks if needed.
-                */
-               if (atomic_read(&global_db_count) > TCMU_GLOBAL_MAX_BLOCKS)
-                       schedule_delayed_work(&tcmu_unmap_work, 0);
+       if (mb->cmd_tail == mb->cmd_head) {
+               /* no more pending commands */
+               del_timer(&udev->cmd_timer);
+
+               if (list_empty(&udev->cmdr_queue)) {
+                       /*
+                        * no more pending or waiting commands so try to
+                        * reclaim blocks if needed.
+                        */
+                       if (atomic_read(&global_db_count) >
+                           TCMU_GLOBAL_MAX_BLOCKS)
+                               schedule_delayed_work(&tcmu_unmap_work, 0);
+               }
        }
 
        return handled;
@@ -1077,13 +1098,15 @@ static int tcmu_check_expired_cmd(int id, void *p, void *data)
                return 0;
 
        is_running = list_empty(&cmd->cmdr_queue_entry);
-       pr_debug("Timing out cmd %u on dev %s that is %s.\n",
-                id, udev->name, is_running ? "inflight" : "queued");
-
-       se_cmd = cmd->se_cmd;
-       cmd->se_cmd = NULL;
 
        if (is_running) {
+               /*
+                * If cmd_time_out is disabled but qfull is set deadline
+                * will only reflect the qfull timeout. Ignore it.
+                */
+               if (!udev->cmd_time_out)
+                       return 0;
+
                set_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags);
                /*
                 * target_complete_cmd will translate this to LUN COMM FAILURE
@@ -1096,16 +1119,18 @@ static int tcmu_check_expired_cmd(int id, void *p, void *data)
                tcmu_free_cmd(cmd);
                scsi_status = SAM_STAT_TASK_SET_FULL;
        }
+
+       pr_debug("Timing out cmd %u on dev %s that is %s.\n",
+                id, udev->name, is_running ? "inflight" : "queued");
+
+       se_cmd = cmd->se_cmd;
+       cmd->se_cmd = NULL;
        target_complete_cmd(se_cmd, scsi_status);
        return 0;
 }
 
-static void tcmu_device_timedout(struct timer_list *t)
+static void tcmu_device_timedout(struct tcmu_dev *udev)
 {
-       struct tcmu_dev *udev = from_timer(udev, t, timeout);
-
-       pr_debug("%s cmd timeout has expired\n", udev->name);
-
        spin_lock(&timed_out_udevs_lock);
        if (list_empty(&udev->timedout_entry))
                list_add_tail(&udev->timedout_entry, &timed_out_udevs);
@@ -1114,6 +1139,22 @@ static void tcmu_device_timedout(struct timer_list *t)
        schedule_delayed_work(&tcmu_unmap_work, 0);
 }
 
+static void tcmu_cmd_timedout(struct timer_list *t)
+{
+       struct tcmu_dev *udev = from_timer(udev, t, cmd_timer);
+
+       pr_debug("%s cmd timeout has expired\n", udev->name);
+       tcmu_device_timedout(udev);
+}
+
+static void tcmu_qfull_timedout(struct timer_list *t)
+{
+       struct tcmu_dev *udev = from_timer(udev, t, qfull_timer);
+
+       pr_debug("%s qfull timeout has expired\n", udev->name);
+       tcmu_device_timedout(udev);
+}
+
 static int tcmu_attach_hba(struct se_hba *hba, u32 host_id)
 {
        struct tcmu_hba *tcmu_hba;
@@ -1151,6 +1192,7 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
 
        udev->hba = hba;
        udev->cmd_time_out = TCMU_TIME_OUT;
+       udev->qfull_time_out = -1;
 
        mutex_init(&udev->cmdr_lock);
 
@@ -1158,7 +1200,8 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
        INIT_LIST_HEAD(&udev->cmdr_queue);
        idr_init(&udev->commands);
 
-       timer_setup(&udev->timeout, tcmu_device_timedout, 0);
+       timer_setup(&udev->qfull_timer, tcmu_qfull_timedout, 0);
+       timer_setup(&udev->cmd_timer, tcmu_cmd_timedout, 0);
 
        init_waitqueue_head(&udev->nl_cmd_wq);
        spin_lock_init(&udev->nl_cmd_lock);
@@ -1213,6 +1256,8 @@ static bool run_cmdr_queue(struct tcmu_dev *udev)
                        goto done;
                }
        }
+       if (list_empty(&udev->cmdr_queue))
+               del_timer(&udev->qfull_timer);
 done:
        return drained;
 }
@@ -1712,7 +1757,8 @@ static void tcmu_destroy_device(struct se_device *dev)
 {
        struct tcmu_dev *udev = TCMU_DEV(dev);
 
-       del_timer_sync(&udev->timeout);
+       del_timer_sync(&udev->cmd_timer);
+       del_timer_sync(&udev->qfull_timer);
 
        mutex_lock(&root_udev_mutex);
        list_del(&udev->node);
@@ -1893,6 +1939,40 @@ static ssize_t tcmu_cmd_time_out_store(struct config_item *item, const char *pag
 }
 CONFIGFS_ATTR(tcmu_, cmd_time_out);
 
+static ssize_t tcmu_qfull_time_out_show(struct config_item *item, char *page)
+{
+       struct se_dev_attrib *da = container_of(to_config_group(item),
+                                               struct se_dev_attrib, da_group);
+       struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
+
+       return snprintf(page, PAGE_SIZE, "%ld\n", udev->qfull_time_out <= 0 ?
+                       udev->qfull_time_out :
+                       udev->qfull_time_out / MSEC_PER_SEC);
+}
+
+static ssize_t tcmu_qfull_time_out_store(struct config_item *item,
+                                        const char *page, size_t count)
+{
+       struct se_dev_attrib *da = container_of(to_config_group(item),
+                                       struct se_dev_attrib, da_group);
+       struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
+       s32 val;
+       int ret;
+
+       ret = kstrtos32(page, 0, &val);
+       if (ret < 0)
+               return ret;
+
+       if (val >= 0) {
+               udev->qfull_time_out = val * MSEC_PER_SEC;
+       } else {
+               printk(KERN_ERR "Invalid qfull timeout value %d\n", val);
+               return -EINVAL;
+       }
+       return count;
+}
+CONFIGFS_ATTR(tcmu_, qfull_time_out);
+
 static ssize_t tcmu_dev_config_show(struct config_item *item, char *page)
 {
        struct se_dev_attrib *da = container_of(to_config_group(item),
@@ -2038,6 +2118,7 @@ CONFIGFS_ATTR(tcmu_, emulate_write_cache);
 
 static struct configfs_attribute *tcmu_attrib_attrs[] = {
        &tcmu_attr_cmd_time_out,
+       &tcmu_attr_qfull_time_out,
        &tcmu_attr_dev_config,
        &tcmu_attr_dev_size,
        &tcmu_attr_emulate_write_cache,