btrfs: restore the thread_pool= behavior in remount for the end I/O workqueues

Commit d7b9416 ("btrfs: remove btrfs_end_io_wq") converted the read
and I/O handling from btrfs_workqueues to Linux workqueues, and as part
of that lost the code to apply the thread_pool= based max_active limit
on remount.  Restore it.

Fixes: d7b9416 ("btrfs: remove btrfs_end_io_wq")
CC: stable@vger.kernel.org # 6.0+
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: Christoph Hellwig

fs/btrfs/super.c

@@ -1631,6 +1631,8 @@ static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
 	btrfs_workqueue_set_max(fs_info->hipri_workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
+	workqueue_set_max_active(fs_info->endio_workers, new_pool_size);
+	workqueue_set_max_active(fs_info->endio_meta_workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);