Re: [PATCH v2 1/8] btrfs: enable a tracepoint when we fail tickets

[Nikolay Borisov <nborisov@suse.com>]

On 29.06.21 г. 16:59, Josef Bacik wrote:
> When debugging early enospc problems it was useful to have a tracepoint
> where we failed all tickets so I could check the state of the enospc
> counters at failure time to validate my fixes.  This adds the tracpoint
> so you can easily get that information.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  fs/btrfs/space-info.c        | 2 ++
>  include/trace/events/btrfs.h | 6 ++++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
> index 392997376a1c..af161eb808a2 100644
> --- a/fs/btrfs/space-info.c
> +++ b/fs/btrfs/space-info.c
> @@ -825,6 +825,8 @@ static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
>  	struct reserve_ticket *ticket;
>  	u64 tickets_id = space_info->tickets_id;
>  
> +	trace_btrfs_fail_all_tickets(fs_info, space_info);
> +
>  	if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
>  		btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
>  		__btrfs_dump_space_info(fs_info, space_info);
> diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
> index c7237317a8b9..3d81ba8c37b9 100644
> --- a/include/trace/events/btrfs.h
> +++ b/include/trace/events/btrfs.h
> @@ -2098,6 +2098,12 @@ DEFINE_EVENT(btrfs_dump_space_info, btrfs_done_preemptive_reclaim,
>  	TP_ARGS(fs_info, sinfo)
>  );
>  
> +DEFINE_EVENT(btrfs_dump_space_info, btrfs_fail_all_tickets,
> +	TP_PROTO(const struct btrfs_fs_info *fs_info,
> +		 const struct btrfs_space_info *sinfo),
> +	TP_ARGS(fs_info, sinfo)
> +);

General suggestion for the dump_space_info - it would be good if
ordered_bytes and delalloc_bytes is also dumped in the tracepoint.

> +
>  TRACE_EVENT(btrfs_reserve_ticket,
>  	TP_PROTO(const struct btrfs_fs_info *fs_info, u64 flags, u64 bytes,
>  		 u64 start_ns, int flush, int error),
>