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Commit cb03c743 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Change the congestion functions to meter the number of async submits as well 



The async submit workqueue was absorbing too many requests, leading to long
stalls where the async submitters were stalling.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 211c17f5

fs/btrfs/ctree.h

+1 −0
Original line number Diff line number Diff line
@@ -522,6 +522,7 @@ struct btrfs_fs_info { 
	struct work_struct async_submit_work;

	spinlock_t end_io_work_lock;

	spinlock_t async_submit_work_lock;

	atomic_t nr_async_submits;



#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)

	struct work_struct trans_work;

fs/btrfs/disk-io.c

+9 −0
Original line number Diff line number Diff line
@@ -453,6 +453,7 @@ int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode, 


	spin_lock(&fs_info->async_submit_work_lock);

	list_add_tail(&async->list, &fs_info->async_submit_work_list);

	atomic_inc(&fs_info->nr_async_submits);

	spin_unlock(&fs_info->async_submit_work_lock);



	queue_work(async_submit_workqueue, &fs_info->async_submit_work);
@@ -906,10 +907,16 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits) 
{

	struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;

	int ret = 0;

	int limit = 256 * info->fs_devices->open_devices;

	struct list_head *cur;

	struct btrfs_device *device;

	struct backing_dev_info *bdi;



	if ((bdi_bits & (1 << BDI_write_congested)) &&

	    atomic_read(&info->nr_async_submits) > limit) {

		return 1;

	}



	list_for_each(cur, &info->fs_devices->devices) {

		device = list_entry(cur, struct btrfs_device, dev_list);

		if (!device->bdev)
@@ -1117,6 +1124,7 @@ static void btrfs_async_submit_work(struct work_struct *work) 
		}

		next = fs_info->async_submit_work_list.next;

		list_del(next);

		atomic_dec(&fs_info->nr_async_submits);

		spin_unlock(&fs_info->async_submit_work_lock);



		async = list_entry(next, struct async_submit_bio, list);
@@ -1179,6 +1187,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, 
	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);

	INIT_LIST_HEAD(&fs_info->space_info);

	btrfs_mapping_init(&fs_info->mapping_tree);

	atomic_set(&fs_info->nr_async_submits, 0);

	fs_info->sb = sb;

	fs_info->max_extent = (u64)-1;

	fs_info->max_inline = 8192 * 1024;