Re: [PATCH 5/5] btrfs: add enospc debug messages for ticket failure

[Nikolay Borisov <nborisov@suse.com>]

On 16.08.19 г. 18:20 ч., Josef Bacik wrote:
> When debugging weird enospc problems it's handy to be able to dump the
> space info when we wake up all tickets, and see what the ticket values
> are.  This helped me figure out cases where we were enospc'ing when we
> shouldn't have been.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

With the suggestion below implemented you can add:

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

> ---
>  fs/btrfs/space-info.c | 32 ++++++++++++++++++++++++--------
>  1 file changed, 24 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
> index 3d3f301bae26..2819fa91c4f0 100644
> --- a/fs/btrfs/space-info.c
> +++ b/fs/btrfs/space-info.c
> @@ -256,14 +256,9 @@ do {									\
>  	spin_unlock(&__rsv->lock);					\
>  } while (0)
>  
> -void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
> -			   struct btrfs_space_info *info, u64 bytes,
> -			   int dump_block_groups)
> +static void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
> +				    struct btrfs_space_info *info)
>  {
> -	struct btrfs_block_group_cache *cache;
> -	int index = 0;
> -
> -	spin_lock(&info->lock);

lockdep_assert_held please

>  	btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull",
>  		   info->flags,
>  		   info->total_bytes - btrfs_space_info_used(info, true),
> @@ -273,7 +268,6 @@ void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
>  		info->total_bytes, info->bytes_used, info->bytes_pinned,
>  		info->bytes_reserved, info->bytes_may_use,
>  		info->bytes_readonly);
> -	spin_unlock(&info->lock);
>  
>  	DUMP_BLOCK_RSV(fs_info, global_block_rsv);
>  	DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
> @@ -281,6 +275,19 @@ void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
>  	DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
>  	DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
>  
> +}
> +
> +void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
> +			   struct btrfs_space_info *info, u64 bytes,
> +			   int dump_block_groups)
> +{
> +	struct btrfs_block_group_cache *cache;
> +	int index = 0;
> +
> +	spin_lock(&info->lock);
> +	__btrfs_dump_space_info(fs_info, info);
> +	spin_unlock(&info->lock);
> +
>  	if (!dump_block_groups)
>  		return;
>  
> @@ -685,6 +692,11 @@ static bool wake_all_tickets(struct btrfs_fs_info *fs_info,
>  	u64 tickets_id = space_info->tickets_id;
>  	u64 first_ticket_bytes = 0;
>  
> +	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);
> +	}
> +
>  	while (!list_empty(&space_info->tickets) &&
>  	       tickets_id == space_info->tickets_id) {
>  		ticket = list_first_entry(&space_info->tickets,
> @@ -705,6 +717,10 @@ static bool wake_all_tickets(struct btrfs_fs_info *fs_info,
>  		else if (first_ticket_bytes > ticket->bytes)
>  			return true;
>  
> +		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
> +			btrfs_info(fs_info, "failing ticket with %llu bytes",
> +				   ticket->bytes);
> +
>  		list_del_init(&ticket->list);
>  		ticket->error = -ENOSPC;
>  		wake_up(&ticket->wait);
>