26  *   1) space_info.  This is the ultimate arbiter of how much space we can use.
245 	space_info->clamp = 1;  in create_space_info()
276 		mixed = 1;  in btrfs_init_space_info()
370 	 * 1/2th of the space. If we can flush, don't let us overcommit  in calc_available_free_space()
371 	 * too much, let it overcommit up to 1/8 of the space.  in calc_available_free_space()
376 		avail >>= 1;  in calc_available_free_space()
395 		return 1;  in btrfs_can_overcommit()
552 	bytes = btrfs_calc_insert_metadata_size(fs_info, 1);  in calc_reclaim_items_nr()
555 		nr = 1;  in calc_reclaim_items_nr()
562 	const u64 bytes = btrfs_calc_delayed_ref_bytes(fs_info, 1);  in calc_delayed_refs_nr()
567 		nr = 1;  in calc_delayed_refs_nr()
672 			btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);  in shrink_delalloc()
674 			time_left = schedule_timeout_killable(1);  in shrink_delalloc()
722 			nr = -1;  in flush_space()
861 	 * 128MiB is 1/4 of the maximum global rsv size.  If we have less than  in need_preemptive_reclaim()
882 	 *     return 1;  in need_preemptive_reclaim()
889 	 * Our clamping range is 2^1 -> 2^8.  Practically speaking that means  in need_preemptive_reclaim()
894 	 *        256GiB                     1GiB                  128GiB  in need_preemptive_reclaim()
895 	 *        128GiB                   512MiB                   64GiB  in need_preemptive_reclaim()
896 	 *         64GiB                   256MiB                   32GiB  in need_preemptive_reclaim()
897 	 *         32GiB                   128MiB                   16GiB  in need_preemptive_reclaim()
898 	 *         16GiB                    64MiB                    8GiB  in need_preemptive_reclaim()
937 	ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;  in need_preemptive_reclaim()
1207 		 * down the to_reclaim by 1/4.  If it takes us down to 0,  in btrfs_preempt_reclaim_metadata_space()
1208 		 * reclaim 1 items worth.  in btrfs_preempt_reclaim_metadata_space()
1212 			to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);  in btrfs_preempt_reclaim_metadata_space()
1219 	if (loops == 1 && !space_info->reclaim_size)  in btrfs_preempt_reclaim_metadata_space()
1220 		space_info->clamp = max(1, space_info->clamp - 1);  in btrfs_preempt_reclaim_metadata_space()
1229  *   1) compression is on and we allocate less space than we reserved
1232  *   For #1 that extra space is reclaimed as soon as the delalloc pages are
1567 	 * writers, because there's not a 1:1 correlation of writing delalloc  in maybe_clamp_preempt()
1573 		space_info->clamp = min(space_info->clamp + 1, 8);  in maybe_clamp_preempt()
1707 				space_info->flush = 1;  in __reserve_bytes()
1767 					      orig_bytes, 1);  in btrfs_reserve_metadata_bytes()
1800 					      data_sinfo->flags, bytes, 1);  in btrfs_reserve_data_bytes()