fs/btrfs/space-info.c

22  * If you want to know about delalloc specifically, there is a separate comment
23  * for that with the delalloc code.  This comment is about how the whole system
119  *     Look at the delalloc comment to get an idea of how much space is reserved
121  *     running delalloc, but usually we need to wait for ordered extents to
641 "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu delalloc %llu super %llu zone_unusable (%llu bytes available) %s",
671  * shrink metadata reservation for delalloc
699 		 * here.  We will take a fraction of the delalloc bytes for our
713 	 * If we are doing more ordered than delalloc we need to just wait on
714 	 * ordered extents, otherwise we'll waste time trying to flush delalloc
777 		 * If we are for preemption we just want a one-shot of delalloc
932 	u64 ordered, delalloc;
992 	 * much delalloc we need for the background flusher to kick in.
1006 	 * If we have more ordered bytes than delalloc bytes then we're either
1007 	 * doing a lot of DIO, or we simply don't have a lot of delalloc waiting
1015 	 * In the case that ordered is larger than delalloc, only include the
1023 	 * cut ordered in half, and if it's still higher than delalloc then we
1025 	 * flushing, and now delalloc == ordered and we stop preemptively
1026 	 * flushing when we could still have several gigs of delalloc to flush.
1029 	delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
1030 	if (ordered >= delalloc)
1177 		 * We do not want to empty the system of delalloc unless we're
1270 		 * reserved for delalloc, so we'll approximate it by subtracting
1273 		 * assume it's tied up in delalloc reservations.
1290 		 * We really want to avoid flushing delalloc too much, as it
1335  *   Space is freed from flushing delalloc in one of two ways.
1340  *   For #1 that extra space is reclaimed as soon as the delalloc pages are
1685 	u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
1690 	 * writers, because there's not a 1:1 correlation of writing delalloc
1692 	 * delayed nodes.  If we're already more ordered than delalloc then
1695 	if (ordered < delalloc)
1725  * flush out space to make room.  It will do this by flushing delalloc if
1872  * flush out space to make room.  It will do this by flushing delalloc if