The following patch will use dio/aio to submit IO to backing file,
then it isn't good to schedule IO concurrently from work, so
use kthread_work.
Signed-off-by: Ming Lei <ming....@canonical.com>
---
drivers/block/loop.c | 79 ++++++++++++++++------------------------------------
drivers/block/loop.h | 10 +++----
2 files changed, 28 insertions(+), 61 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e9f563d..94c9eec 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -666,6 +666,23 @@ static void loop_config_discard(struct loop_device *lo)
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
}
+static void loop_unprepare_queue(struct loop_device *lo)
+{
+ flush_kthread_worker(&lo->worker);
+ kthread_stop(lo->worker_task);
+}
+
+static int loop_prepare_queue(struct loop_device *lo)
+{
+ init_kthread_worker(&lo->worker);
+ lo->worker_task = kthread_run(kthread_worker_fn,
+ &lo->worker, "loop%d", lo->lo_number);
+ if (IS_ERR(lo->worker_task))
+ return -ENOMEM;
+ set_user_nice(lo->worker_task, MIN_NICE);
+ return 0;
+}
+
static int loop_set_fd(struct loop_device *lo, fmode_t mode,
struct block_device *bdev, unsigned int arg)
{
@@ -723,11 +740,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t
mode,
size = get_loop_size(lo, file);
if ((loff_t)(sector_t)size != size)
goto out_putf;
- error = -ENOMEM;
- lo->wq = alloc_workqueue("kloopd%d",
- WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16,
- lo->lo_number);
- if (!lo->wq)
+ error = loop_prepare_queue(lo);
+ if (error)
goto out_putf;
error = 0;
@@ -876,8 +890,7 @@ static int loop_clr_fd(struct loop_device *lo)
lo->lo_flags = 0;
if (!part_shift)
lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
- destroy_workqueue(lo->wq);
- lo->wq = NULL;
+ loop_unprepare_queue(lo);
mutex_unlock(&lo->lo_ctl_mutex);
/*
* Need not hold lo_ctl_mutex to fput backing file.
@@ -1438,23 +1451,7 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
if (lo->lo_state != Lo_bound)
return -EIO;
- if (cmd->rq->cmd_flags & REQ_WRITE) {
- struct loop_device *lo = cmd->rq->q->queuedata;
- bool need_sched = true;
-
- spin_lock_irq(&lo->lo_lock);
- if (lo->write_started)
- need_sched = false;
- else
- lo->write_started = true;
- list_add_tail(&cmd->list, &lo->write_cmd_head);
- spin_unlock_irq(&lo->lo_lock);
-
- if (need_sched)
- queue_work(lo->wq, &lo->write_work);
- } else {
- queue_work(lo->wq, &cmd->read_work);
- }
+ queue_kthread_work(&lo->worker, &cmd->work);
return BLK_MQ_RQ_QUEUE_OK;
}
@@ -1476,35 +1473,10 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
blk_mq_complete_request(cmd->rq);
}
-static void loop_queue_write_work(struct work_struct *work)
-{
- struct loop_device *lo =
- container_of(work, struct loop_device, write_work);
- LIST_HEAD(cmd_list);
-
- spin_lock_irq(&lo->lo_lock);
- repeat:
- list_splice_init(&lo->write_cmd_head, &cmd_list);
- spin_unlock_irq(&lo->lo_lock);
-
- while (!list_empty(&cmd_list)) {
- struct loop_cmd *cmd = list_first_entry(&cmd_list,
- struct loop_cmd, list);
- list_del_init(&cmd->list);
- loop_handle_cmd(cmd);
- }
-
- spin_lock_irq(&lo->lo_lock);
- if (!list_empty(&lo->write_cmd_head))
- goto repeat;
- lo->write_started = false;
- spin_unlock_irq(&lo->lo_lock);
-}
-
-static void loop_queue_read_work(struct work_struct *work)
+static void loop_queue_work(struct kthread_work *work)
{
struct loop_cmd *cmd =
- container_of(work, struct loop_cmd, read_work);
+ container_of(work, struct loop_cmd, work);
loop_handle_cmd(cmd);
}
@@ -1516,7 +1488,7 @@ static int loop_init_request(void *data, struct request
*rq,
struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
cmd->rq = rq;
- INIT_WORK(&cmd->read_work, loop_queue_read_work);
+ init_kthread_work(&cmd->work, loop_queue_work);
return 0;
}
@@ -1578,9 +1550,6 @@ static int loop_add(struct loop_device **l, int i)
*/
queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, lo->lo_queue);
- INIT_LIST_HEAD(&lo->write_cmd_head);
- INIT_WORK(&lo->write_work, loop_queue_write_work);
-
disk = lo->lo_disk = alloc_disk(1 << part_shift);
if (!disk)
goto out_free_queue;
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index 49564ed..54c6aa5 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -14,7 +14,7 @@
#include <linux/blk-mq.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
-#include <linux/workqueue.h>
+#include <linux/kthread.h>
#include <uapi/linux/loop.h>
/* Possible states of device */
@@ -54,12 +54,10 @@ struct loop_device {
gfp_t old_gfp_mask;
spinlock_t lo_lock;
- struct workqueue_struct *wq;
- struct list_head write_cmd_head;
- struct work_struct write_work;
- bool write_started;
int lo_state;
struct mutex lo_ctl_mutex;
+ struct kthread_worker worker;
+ struct task_struct *worker_task;
struct request_queue *lo_queue;
struct blk_mq_tag_set tag_set;
@@ -67,7 +65,7 @@ struct loop_device {
};
struct loop_cmd {
- struct work_struct read_work;
+ struct kthread_work work;
struct request *rq;
struct list_head list;
};
--
1.9.1
--
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