Commit b8494823 authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

md: initialize 'writes_pending' while allocating mddev 



Currently 'writes_pending' is initialized in pers->run for raid1/5/10,
and it's freed while deleing mddev, instead of pers->free. pers->run can
be called multiple times before mddev is deleted, and a helper
mddev_init_writes_pending() is used to prevent 'writes_pending' to be
initialized multiple times, this usage is safe but a litter weird.

On the other hand, 'writes_pending' is only initialized for raid1/5/10,
however, it's used in common layer, for example:

array_state_store
 set_in_sync
  if (!mddev->in_sync) -> in_sync is used for all levels
   // access writes_pending

There might be some implicit dependency that I don't recognized to make
sure 'writes_pending' can only be accessed for raid1/5/10, but there are
no comments about that.

By the way, it make sense to initialize 'writes_pending' in common layer
because there are already three levels use it.

Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230825030956.1527023-3-yukuai1@huaweicloud.com
parent d58eff83

drivers/md/md.c

+12 −17
Original line number Diff line number Diff line
@@ -646,6 +646,8 @@ static void active_io_release(struct percpu_ref *ref) 
	wake_up(&mddev->sb_wait);

}



static void no_op(struct percpu_ref *r) {}



int mddev_init(struct mddev *mddev)

{
@@ -653,6 +655,15 @@ int mddev_init(struct mddev *mddev) 
			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL))

		return -ENOMEM;



	if (percpu_ref_init(&mddev->writes_pending, no_op,

			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {

		percpu_ref_exit(&mddev->active_io);

		return -ENOMEM;

	}



	/* We want to start with the refcount at zero */

	percpu_ref_put(&mddev->writes_pending);



	mutex_init(&mddev->open_mutex);

	mutex_init(&mddev->reconfig_mutex);

	mutex_init(&mddev->sync_mutex);
@@ -685,6 +696,7 @@ EXPORT_SYMBOL_GPL(mddev_init); 
void mddev_destroy(struct mddev *mddev)

{

	percpu_ref_exit(&mddev->active_io);

	percpu_ref_exit(&mddev->writes_pending);

}

EXPORT_SYMBOL_GPL(mddev_destroy);
@@ -5628,21 +5640,6 @@ static void mddev_delayed_delete(struct work_struct *ws) 
	kobject_put(&mddev->kobj);

}



static void no_op(struct percpu_ref *r) {}



int mddev_init_writes_pending(struct mddev *mddev)

{

	if (mddev->writes_pending.percpu_count_ptr)

		return 0;

	if (percpu_ref_init(&mddev->writes_pending, no_op,

			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL) < 0)

		return -ENOMEM;

	/* We want to start with the refcount at zero */

	percpu_ref_put(&mddev->writes_pending);

	return 0;

}

EXPORT_SYMBOL_GPL(mddev_init_writes_pending);



struct mddev *md_alloc(dev_t dev, char *name)

{

	/*
@@ -6323,7 +6320,6 @@ void md_stop(struct mddev *mddev) 
	 */

	__md_stop_writes(mddev);

	__md_stop(mddev);

	percpu_ref_exit(&mddev->writes_pending);

}



EXPORT_SYMBOL_GPL(md_stop);
@@ -7907,7 +7903,6 @@ static void md_free_disk(struct gendisk *disk) 
{

	struct mddev *mddev = disk->private_data;



	percpu_ref_exit(&mddev->writes_pending);

	mddev_free(mddev);

}

drivers/md/md.h

+0 −1
Original line number Diff line number Diff line
@@ -771,7 +771,6 @@ extern void md_unregister_thread(struct mddev *mddev, struct md_thread __rcu **t 
extern void md_wakeup_thread(struct md_thread __rcu *thread);

extern void md_check_recovery(struct mddev *mddev);

extern void md_reap_sync_thread(struct mddev *mddev);

extern int mddev_init_writes_pending(struct mddev *mddev);

extern bool md_write_start(struct mddev *mddev, struct bio *bi);

extern void md_write_inc(struct mddev *mddev, struct bio *bi);

extern void md_write_end(struct mddev *mddev);

drivers/md/raid1.c

+1 −2
Original line number Diff line number Diff line
@@ -3122,8 +3122,7 @@ static int raid1_run(struct mddev *mddev) 
			mdname(mddev));

		return -EIO;

	}

	if (mddev_init_writes_pending(mddev) < 0)

		return -ENOMEM;



	/*

	 * copy the already verified devices into our private RAID1

	 * bookkeeping area. [whatever we allocate in run(),

drivers/md/raid10.c

+0 −3
Original line number Diff line number Diff line
@@ -4154,9 +4154,6 @@ static int raid10_run(struct mddev *mddev) 
	sector_t min_offset_diff = 0;

	int first = 1;



	if (mddev_init_writes_pending(mddev) < 0)

		return -ENOMEM;



	if (mddev->private == NULL) {

		conf = setup_conf(mddev);

		if (IS_ERR(conf))

drivers/md/raid5.c

+0 −3
Original line number Diff line number Diff line
@@ -7778,9 +7778,6 @@ static int raid5_run(struct mddev *mddev) 
	long long min_offset_diff = 0;

	int first = 1;



	if (mddev_init_writes_pending(mddev) < 0)

		return -ENOMEM;



	if (mddev->recovery_cp != MaxSector)

		pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",

			  mdname(mddev));