Commit 48df498d authored by Guoqing Jiang's avatar Guoqing Jiang Committed by Shaohua Li
Browse files

md: move bitmap_destroy to the beginning of __md_stop 



Since we have switched to sync way to handle METADATA_UPDATED
msg for md-cluster, then process_metadata_update is depended
on mddev->thread->wqueue.

With the new change, clustered raid could possible hang if
array received a METADATA_UPDATED msg after array unregistered
mddev->thread, so we need to stop clustered raid (bitmap_destroy
-> bitmap_free -> md_cluster_stop) earlier than unregister
thread (mddev_detach -> md_unregister_thread).

And this change should be safe for non-clustered raid since
all writes are stopped before the destroy. Also in md_run,
we activate the personality (pers->run()) before activating
the bitmap (bitmap_create()). So it is pleasingly symmetric
to stop the bitmap (bitmap_destroy()) before stopping the
personality (__md_stop() calls pers->free()), we achieve this
by move bitmap_destroy to the beginning of __md_stop.

But we don't want to break the codes for waiting behind IO as
Shaohua mentioned, so introduce bitmap_wait_behind_writes to
call the codes, and call the new fun in both mddev_detach and
bitmap_destroy, then we will not break original behind IO code
and also fit the new condition well.

Signed-off-by: default avatarGuoqing Jiang <gqjiang@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent ea17481f

drivers/md/bitmap.c

+16 −0
Original line number Diff line number Diff line
@@ -1764,6 +1764,20 @@ void bitmap_free(struct bitmap *bitmap) 
}

EXPORT_SYMBOL(bitmap_free);



void bitmap_wait_behind_writes(struct mddev *mddev)

{

	struct bitmap *bitmap = mddev->bitmap;



	/* wait for behind writes to complete */

	if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {

		pr_debug("md:%s: behind writes in progress - waiting to stop.\n",

			 mdname(mddev));

		/* need to kick something here to make sure I/O goes? */

		wait_event(bitmap->behind_wait,

			   atomic_read(&bitmap->behind_writes) == 0);

	}

}



void bitmap_destroy(struct mddev *mddev)

{

	struct bitmap *bitmap = mddev->bitmap;
@@ -1771,6 +1785,8 @@ void bitmap_destroy(struct mddev *mddev) 
	if (!bitmap) /* there was no bitmap */

		return;



	bitmap_wait_behind_writes(mddev);



	mutex_lock(&mddev->bitmap_info.mutex);

	spin_lock(&mddev->lock);

	mddev->bitmap = NULL; /* disconnect from the md device */

drivers/md/bitmap.h

+1 −0
Original line number Diff line number Diff line
@@ -271,6 +271,7 @@ struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot); 
int bitmap_copy_from_slot(struct mddev *mddev, int slot,

				sector_t *lo, sector_t *hi, bool clear_bits);

void bitmap_free(struct bitmap *bitmap);

void bitmap_wait_behind_writes(struct mddev *mddev);

#endif



#endif

drivers/md/md.c

+2 −11
Original line number Diff line number Diff line
@@ -5675,15 +5675,7 @@ EXPORT_SYMBOL_GPL(md_stop_writes); 


static void mddev_detach(struct mddev *mddev)

{

	struct bitmap *bitmap = mddev->bitmap;

	/* wait for behind writes to complete */

	if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {

		pr_debug("md:%s: behind writes in progress - waiting to stop.\n",

			 mdname(mddev));

		/* need to kick something here to make sure I/O goes? */

		wait_event(bitmap->behind_wait,

			   atomic_read(&bitmap->behind_writes) == 0);

	}

	bitmap_wait_behind_writes(mddev);

	if (mddev->pers && mddev->pers->quiesce) {

		mddev->pers->quiesce(mddev, 1);

		mddev->pers->quiesce(mddev, 0);
@@ -5696,6 +5688,7 @@ static void mddev_detach(struct mddev *mddev) 
static void __md_stop(struct mddev *mddev)

{

	struct md_personality *pers = mddev->pers;

	bitmap_destroy(mddev);

	mddev_detach(mddev);

	/* Ensure ->event_work is done */

	flush_workqueue(md_misc_wq);
@@ -5716,7 +5709,6 @@ void md_stop(struct mddev *mddev) 
	 * This is called from dm-raid

	 */

	__md_stop(mddev);

	bitmap_destroy(mddev);

	if (mddev->bio_set)

		bioset_free(mddev->bio_set);

}
@@ -5854,7 +5846,6 @@ static int do_md_stop(struct mddev *mddev, int mode, 
	if (mode == 0) {

		pr_info("md: %s stopped.\n", mdname(mddev));



		bitmap_destroy(mddev);

		if (mddev->bitmap_info.file) {

			struct file *f = mddev->bitmap_info.file;

			spin_lock(&mddev->lock);

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