Re: [RFC PATCH v2 2/4] jbd2: introduce some new log interfaces

brookxu
2021-01-25T16:01:09Z

Jan Kara wrote on 2021/1/25 22:54:
> On Sat 23-01-21 20:00:44, Chunguang Xu wrote:
>> From: Chunguang Xu <brookxu@tencent.com>
>>
>> Compared to directly using numbers to indicate levels, using abstract
>> error, warn, notice, info, debug to indicate levels may be more
>> convenient for code reading and writing. Similar to other kernel
>> modules, some basic log interfaces are introduced.
>>
>> Signed-off-by: Chunguang Xu <brookxu@tencent.com>
>
> One more thing I've noticed when reading this patch:
>
>> +
>> +#ifdef CONFIG_JBD2_DEBUG
>> +/*
>> + * Define JBD2_EXPENSIVE_CHECKING to enable more expensive internal
>> + * consistency checks. By default we don't do this unless
>> + * CONFIG_JBD2_DEBUG is on.
>> + */
>> +#define JBD2_EXPENSIVE_CHECKING
>> +extern ushort jbd2_journal_enable_debug;
>> +void jbd2_log(int level, journal_t *j, const char *file, const char *func,
>> + unsigned int line, const char *fmt, ...);
>> +
>> +#define JBD2_ERR 1 /* error conditions */
>> +#define JBD2_WARN 2 /* warning conditions */
>> +#define JBD2_NOTICE 3 /* normal but significant condition */
>> +#define JBD2_INFO 4 /* informational */
>> +#define JBD2_DEBUG 5 /* debug-level messages */
>
> This is actually not true. All the jbd_debug() messages are really debug
> messages, not errors, not warnings. It is just a different level of detail.
> Honestly, these days, I'd rather discard all the levels, use pr_debug()
> function to print these messages inside jdb2_debug() and defer to
> CONFIG_DYNAMIC_DEBUG framework for configuration of which messages are
> interesting for a particular debug session.

From a certain point, this is indeed, maybe the changes here are not necessary.
Thanks.

> Honza
>
>> +
>> +#define jbd2_err(j, fmt, a...) \
>> + jbd2_log(JBD2_ERR, j, __FILE__, __func__, __LINE__, (fmt), ##a)
>> +
>> +#define jbd2_warn(j, fmt, a...) \
>> + jbd2_log(JBD2_WARN, j, __FILE__, __func__, __LINE__, (fmt), ##a)
>> +
>> +#define jbd2_notice(j, fmt, a...) \
>> + jbd2_log(JBD2_NOTICE, j, __FILE__, __func__, __LINE__, (fmt), ##a)
>> +
>> +#define jbd2_info(j, fmt, a...) \
>> + jbd2_log(JBD2_INFO, j, __FILE__, __func__, __LINE__, (fmt), ##a)
>> +
>> +#define jbd2_debug(j, fmt, a...) \
>> + jbd2_log(JBD2_DEBUG, j, __FILE__, __func__, __LINE__, (fmt), ##a)
>> +
>> +#else
>> +
>> +#define jbd2_err(j, fmt, a...)
>> +#define jbd2_warn(j, fmt, a...)
>> +#define jbd2_notice(j, fmt, a...)
>> +#define jbd2_info(j, fmt, a...)
>> +#define jbd2_debug(j, fmt, a...)
>> +
>> +#endif
>> #endif
>>
>> /*
>> --
>> 2.30.0
>>