Re: [PATCH v0 0/1] Add Btrfs messages to printk index

[Nikolay Borisov <nborisov@suse.com>]

On 17.03.22 г. 7:13 ч., Jonathan Lassoff wrote:
> In order for end users to quickly react to new issues that come up in
> production, it is proving useful to leverage this printk indexing system. This
> printk index enables kernel developers to use calls to printk() with changable
> ad-hoc format strings, while still enabling end users to detect changes and
> develop a semi-stable interface for detecting and parsing these messages.
> 
> So that detailed Btrfs messages are captured by this printk index, this patch
> wraps btrfs_printk and btrfs_handle_fs_error with macros.
> 
> Signed-off-by: Jonathan Lassoff <jof@thejof.com>
> ---
>   fs/btrfs/ctree.h | 28 ++++++++++++++++++++++++++--
>   fs/btrfs/super.c |  6 +++---
>   2 files changed, 29 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index ebb2d109e8bb..cc768f71d0a5 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -3344,9 +3344,22 @@ void btrfs_no_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
>   }
>   
>   #ifdef CONFIG_PRINTK
> +#define btrfs_printk(fs_info, fmt, args...)                          \
> +do {                                                                 \
> +	printk_index_subsys_emit("%sBTRFS %s (device %s): ", NULL, fmt); \
> +	_btrfs_printk(fs_info, fmt, ##args);                             \
> +} while (0)
>   __printf(2, 3)
>   __cold
> -void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
> +void _btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
> +#elif defined(CONFIG_PRINTK)

But you already checked for #idef CONFIG_PRINTK ? In case CONFIG_PRINTK 
is not defined we'll call btrfs_no_printk as btrfs_printk would be 
compiled-out. So what's your intention here?

> +#define btrfs_printk(fs_info, fmt, args...)                          \
> +do {                                                                 \
> +	_btrfs_printk(fs_info, fmt, ##args);                             \
> +} while (0)
> +__printf(2, 3)
> +__cold
> +void _btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
>   #else
>   #define btrfs_printk(fs_info, fmt, args...) \
>   	btrfs_no_printk(fs_info, fmt, ##args)
> @@ -3598,11 +3611,22 @@ do {								\
>   				  __LINE__, (errno));		\
>   } while (0)
>   


<snip>