From db161806dc5615a42893a1df7d803d12890699d9 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Tue, 10 Mar 2020 11:00:35 +0200 Subject: [PATCH] btrfs: account ticket size at add/delete time 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 Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/space-info.c | 12 ++++++------ fs/btrfs/space-info.h | 7 +++++++ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c index 9cb511d8cd9d..8b0fe053a25d 100644 --- a/fs/btrfs/space-info.c +++ b/fs/btrfs/space-info.c @@ -389,6 +389,8 @@ 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); @@ -784,16 +786,12 @@ static inline u64 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info, struct btrfs_space_info *space_info) { - struct reserve_ticket *ticket; 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); @@ -1192,8 +1190,10 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info, * 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); diff --git a/fs/btrfs/space-info.h b/fs/btrfs/space-info.h index 24514cd2c6c1..0a5001ef1481 100644 --- 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.