Re: [PATCH 7/9] btrfs: fix may_commit_transaction to deal with no partial filling

[Nikolay Borisov <nborisov@suse.com>]

On 22.08.19 г. 22:11 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, and subtract
> this from the ticket we have and use that amount to determine if we will
> need to commit to reclaim enough space.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  fs/btrfs/space-info.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
> index dd4adfa75a71..cec6db0c41cc 100644
> --- a/fs/btrfs/space-info.c
> +++ b/fs/btrfs/space-info.c
> @@ -473,12 +473,19 @@ 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;
> +
>  	if (!list_empty(&space_info->priority_tickets))
>  		ticket = list_first_entry(&space_info->priority_tickets,
>  					  struct reserve_ticket, list);
> @@ -486,6 +493,11 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info,
>  		ticket = list_first_entry(&space_info->tickets,
>  					  struct reserve_ticket, list);
>  	bytes_needed = (ticket) ? ticket->bytes : 0;
> +
> +	if (bytes_needed > cur_free_bytes)
> +		bytes_needed -= cur_free_bytes;
> +	else
> +		bytes_needed = 0;
>  	spin_unlock(&space_info->lock);
>  
>  	if (!bytes_needed)
>