From: Nikolay Borisov <nborisov@suse.com>
Date: Tue, 10 Mar 2020 11:00:35 +0200
Subject: btrfs: account ticket size at add/delete time
Git-commit: db161806dc5615a42893a1df7d803d12890699d9
Patch-mainline: v5.7-rc1
References: bsc#1141456
Instead of iterating all pending tickets on the normal/priority list to
sum their total size the cost can be amortized across ticket addition/
removal. This turns O(n) + O(m) (where n is the size of the normal list
and m of the priority list) into O(1). This will mostly have effect in
workloads that experience heavy flushing.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/space-info.c | 11 ++++++-----
fs/btrfs/space-info.h | 7 +++++++
2 files changed, 13 insertions(+), 5 deletions(-)
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -264,6 +264,8 @@ again:
space_info,
ticket->bytes);
list_del_init(&ticket->list);
+ ASSERT(space_info->reclaim_size >= ticket->bytes);
+ space_info->reclaim_size -= ticket->bytes;
ticket->bytes = 0;
space_info->tickets_id++;
wake_up(&ticket->wait);
@@ -663,12 +665,9 @@ btrfs_calc_reclaim_metadata_size(struct
u64 used;
u64 avail;
u64 expected;
- u64 to_reclaim = 0;
+ u64 to_reclaim = space_info->reclaim_size;
- list_for_each_entry(ticket, &space_info->tickets, list)
- to_reclaim += ticket->bytes;
- list_for_each_entry(ticket, &space_info->priority_tickets, list)
- to_reclaim += ticket->bytes;
+ lockdep_assert_held(&space_info->lock);
avail = calc_available_free_space(fs_info, space_info,
BTRFS_RESERVE_FLUSH_ALL);
@@ -1067,8 +1066,10 @@ static int __reserve_metadata_bytes(stru
* the list and we will do our own flushing further down.
*/
if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {
+ ASSERT(space_info->reclaim_size >= 0);
ticket.bytes = orig_bytes;
ticket.error = 0;
+ space_info->reclaim_size += ticket.bytes;
init_waitqueue_head(&ticket.wait);
if (flush == BTRFS_RESERVE_FLUSH_ALL) {
list_add_tail(&ticket.list, &space_info->tickets);
--- a/fs/btrfs/space-info.h
+++ b/fs/btrfs/space-info.h
@@ -54,6 +54,13 @@ struct btrfs_space_info {
struct list_head ro_bgs;
struct list_head priority_tickets;
struct list_head tickets;
+
+ /*
+ * Size of space that needs to be reclaimed in order to satisfy pending
+ * tickets
+ */
+ u64 reclaim_size;
+
/*
* tickets_id just indicates the next ticket will be handled, so note
* it's not stored per ticket.