From ef1317a1b9a347cdc3967a2048046e8fb4db94ba Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 22 Aug 2019 15:10:54 -0400 Subject: [PATCH] btrfs: do not allow reservations if we have pending tickets If we already have tickets on the list we don't want to steal their reservations. This is a preparation patch for upcoming changes, technically this shouldn't happen today because of the way we add bytes to tickets before adding them to the space_info in most cases. This does not change the FIFO nature of reserve tickets, it simply allows us to enforce it in a different way. Previously it was enforced because any new space would be added to the first ticket on the list, which would result in new reservations getting a reserve ticket. This replaces that mechanism by simply checking to see if we have outstanding reserve tickets and skipping straight to adding a ticket for our reservation. Reviewed-by: Nikolay Borisov Signed-off-by: Josef Bacik Signed-off-by: David Sterba --- fs/btrfs/space-info.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c index bea7ae0a9739..918bffb6ba30 100644 --- a/fs/btrfs/space-info.c +++ b/fs/btrfs/space-info.c @@ -993,6 +993,7 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info, struct reserve_ticket ticket; u64 used; int ret = 0; + bool pending_tickets; ASSERT(orig_bytes); ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL); @@ -1000,14 +1001,17 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info, spin_lock(&space_info->lock); ret = -ENOSPC; used = btrfs_space_info_used(space_info, true); + pending_tickets = !list_empty(&space_info->tickets) || + !list_empty(&space_info->priority_tickets); /* * Carry on if we have enough space (short-circuit) OR call * can_overcommit() to ensure we can overcommit to continue. */ - if ((used + orig_bytes <= space_info->total_bytes) || - can_overcommit(fs_info, space_info, orig_bytes, flush, - system_chunk)) { + if (!pending_tickets && + ((used + orig_bytes <= space_info->total_bytes) || + can_overcommit(fs_info, space_info, orig_bytes, flush, + system_chunk))) { btrfs_space_info_update_bytes_may_use(fs_info, space_info, orig_bytes); trace_btrfs_space_reservation(fs_info, "space_info",