On 16.08.19 г. 17:19 ч., Josef Bacik wrote:
> Now that we aren't partially filling tickets we may have some slack
> space left in the space_info. We need to account for this in
> may_commit_transaction, otherwise we may choose to not commit the
> transaction despite it actually having enough space to satisfy our
> ticket.
>
> Calculate the free space we have in the space_info, if any. Then check
> to see if its >= the amount of bytes_needed after we've accounted for
> the space being used by the delayed refs rsv. If it's not subtract it
> from the bytes_needed before doing the final pinned check. If we still
> don't have enough space then we are truly out of space.
>
> Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
> ---
> fs/btrfs/space-info.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
> index bd485be783b8..f79afdc04925 100644
> --- a/fs/btrfs/space-info.c
> +++ b/fs/btrfs/space-info.c
> @@ -471,12 +471,19 @@ static int may_commit_transaction(struct btrfs_fs_info
> *fs_info,
> struct btrfs_trans_handle *trans;
> u64 bytes_needed;
> u64 reclaim_bytes = 0;
> + u64 cur_free_bytes = 0;
>
> trans = (struct btrfs_trans_handle *)current->journal_info;
> if (trans)
> return -EAGAIN;
>
> spin_lock(&space_info->lock);
> + cur_free_bytes = btrfs_space_info_used(space_info, true);
> + if (cur_free_bytes < space_info->total_bytes)
> + cur_free_bytes = space_info->total_bytes - cur_free_bytes;
> + else
> + cur_free_bytes = 0;
> +
Why don't you subtract cur_free_bytes from bytes_needed right here,
giving you more chance to hit the:
if (reclaim_bytes >= bytes_needed)
goto commit;
> if (!list_empty(&space_info->priority_tickets))
> ticket = list_first_entry(&space_info->priority_tickets,
> struct reserve_ticket, list);
> @@ -522,6 +529,18 @@ static int may_commit_transaction(struct btrfs_fs_info
> *fs_info,
> goto commit;
> bytes_needed -= reclaim_bytes;
>
> + /*
> + * We don't partially fill tickets anymore, so we could have some free
> + * bytes in the space_info already, just not enough to satisfy the
> + * ticket. If bytes_needed is already below cur_free_bytes after taking
> + * away the delayed refs and delayed rsv's then we can commit.
> + * Otherwise subtract our cur_free_bytes from bytes_needed before we
> + * check pinned.
> + */
> + if (bytes_needed <= cur_free_bytes)
> + goto commit;
If you do that you won't need that check because you have already
accounted for the current free space.
> + bytes_needed -= cur_free_bytes;
And this line will be gone as well.
> +
> if (__percpu_counter_compare(&space_info->total_bytes_pinned,
> bytes_needed,
> BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0)
>
