From: Josef Bacik <josef@toxicpanda.com>
Date: Thu, 22 Aug 2019 15:10:54 -0400
Subject: btrfs: do not allow reservations if we have pending tickets
Git-commit: ef1317a1b9a347cdc3967a2048046e8fb4db94ba
Patch-mainline: v5.4-rc1
References: bsc#1141456
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 <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
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",