Commit ee4a36f4 authored by Coly Li's avatar Coly Li Committed by Jens Axboe
Browse files

bcache: use delayed kworker fo asynchronous devices registration 



This patch changes the asynchronous registration kworker to a delayed
kworker. There is probability queue_work() queues the async registration
kworker to the same CPU (even though very little), then the process
which writing sysfs interface to reigster bcache device may won't return
immeidately. queue_delayed_work() in this patch will delay 10 jiffies
before insert the kworker to run queue, which makes sure the registering
process may always returns to user space in time.

Fixes: 9e23ccf8 ("bcache: asynchronous devices registration")
Signed-off-by: default avatarColy Li <colyli@suse.de>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent dcacbc12

drivers/md/bcache/super.c

+8 −6
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/genhd.h>

#include <linux/idr.h>

#include <linux/kthread.h>

#include <linux/workqueue.h>

#include <linux/module.h>

#include <linux/random.h>

#include <linux/reboot.h>
@@ -2380,7 +2381,7 @@ static bool bch_is_open(struct block_device *bdev) 
}



struct async_reg_args {

	struct work_struct reg_work;

	struct delayed_work reg_work;

	char *path;

	struct cache_sb *sb;

	struct cache_sb_disk *sb_disk;
@@ -2391,7 +2392,7 @@ static void register_bdev_worker(struct work_struct *work) 
{

	int fail = false;

	struct async_reg_args *args =

		container_of(work, struct async_reg_args, reg_work);

		container_of(work, struct async_reg_args, reg_work.work);

	struct cached_dev *dc;



	dc = kzalloc(sizeof(*dc), GFP_KERNEL);
@@ -2421,7 +2422,7 @@ static void register_cache_worker(struct work_struct *work) 
{

	int fail = false;

	struct async_reg_args *args =

		container_of(work, struct async_reg_args, reg_work);

		container_of(work, struct async_reg_args, reg_work.work);

	struct cache *ca;



	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
@@ -2449,11 +2450,12 @@ out: 
static void register_device_aync(struct async_reg_args *args)

{

	if (SB_IS_BDEV(args->sb))

		INIT_WORK(&args->reg_work, register_bdev_worker);

		INIT_DELAYED_WORK(&args->reg_work, register_bdev_worker);

	else

		INIT_WORK(&args->reg_work, register_cache_worker);

		INIT_DELAYED_WORK(&args->reg_work, register_cache_worker);



	queue_work(system_wq, &args->reg_work);

	/* 10 jiffies is enough for a delay */

	queue_delayed_work(system_wq, &args->reg_work, 10);

}



static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,

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