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Message-ID: <6f72c639-53a7-411c-4672-f559fd63d347@gmail.com>
Date: Sat, 23 Jan 2021 11:15:44 +0800
From: brookxu <brookxu.cn@...il.com>
To: harshad shirwadkar <harshadshirwadkar@...il.com>
Cc: "Theodore Y. Ts'o" <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>, jack@...e.com,
Ext4 Developers List <linux-ext4@...r.kernel.org>,
linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/4] jbd2: make jdb2_debug module parameter per device
En...，your idea maybe better, thanks for your time.
harshad shirwadkar wrote on 2021/1/23 3:00:
> I wonder if we should retain the existing module param as well apart
> from the new device specific logging switch? If that switch is
> enabled, we'll get jbd2 logs for all the devices. Given that the old
> jbd2_debug interface was a module param, I wonder somebody somewhere
> might have infrastructure on top of that to enable debugging for jbd2?
> And by removing this interface we may accidentally break them?
>
> On Thu, Jan 21, 2021 at 10:48 PM Chunguang Xu <brookxu.cn@...il.com> wrote:
>>
>> From: Chunguang Xu <brookxu@...cent.com>
>>
>> On a multi-disk machine, because jbd2's debugging switch is global,this
>> confuses the logs of multiple disks. It is not easy to distinguish the
>> logs of each disk and the amount of generated logs is very large. Or a
>> separate debugging switch for each disk would be better, so that you
>> can easily distinguish the logs of a certain disk.
>>
>> Signed-off-by: Chunguang Xu <brookxu@...cent.com>
>> ---
>> fs/jbd2/journal.c | 63 +++++++++++++++++++++++++++++++++++--------
>> fs/jbd2/transaction.c | 2 +-
>> include/linux/jbd2.h | 7 +++++
>> 3 files changed, 60 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
>> index 2dc944442802..ae147cc713c7 100644
>> --- a/fs/jbd2/journal.c
>> +++ b/fs/jbd2/journal.c
>> @@ -48,14 +48,6 @@
>> #include <linux/uaccess.h>
>> #include <asm/page.h>
>>
>> -#ifdef CONFIG_JBD2_DEBUG
>> -ushort jbd2_journal_enable_debug __read_mostly;
>> -EXPORT_SYMBOL(jbd2_journal_enable_debug);
>> -
>> -module_param_named(jbd2_debug, jbd2_journal_enable_debug, ushort, 0644);
>> -MODULE_PARM_DESC(jbd2_debug, "Debugging level for jbd2");
>> -#endif
>> -
>> EXPORT_SYMBOL(jbd2_journal_extend);
>> EXPORT_SYMBOL(jbd2_journal_stop);
>> EXPORT_SYMBOL(jbd2_journal_lock_updates);
>> @@ -101,13 +93,13 @@ EXPORT_SYMBOL(jbd2_inode_cache);
>> static int jbd2_journal_create_slab(size_t slab_size);
>>
>> #ifdef CONFIG_JBD2_DEBUG
>> -void __jbd2_debug(int level, const char *file, const char *func,
>> +void jbd2_log(int level, journal_t *j, const char *file, const char *func,
>> unsigned int line, const char *fmt, ...)
>> {
>> struct va_format vaf;
>> va_list args;
>>
>> - if (level > jbd2_journal_enable_debug)
>> + if (!j || level > j->j_debug_level)
>> return;
>> va_start(args, fmt);
>> vaf.fmt = fmt;
>> @@ -115,7 +107,7 @@ void __jbd2_debug(int level, const char *file, const char *func,
>> printk(KERN_DEBUG "%s: (%s, %u): %pV", file, func, line, &vaf);
> Now that you have journal_t passed to jbd2_log, it would also be good
> to print the name of the device in this message. I think you can use
> j->j_devname for that.
>
> Thanks,
> Harshad
>> va_end(args);
>> }
>> -EXPORT_SYMBOL(__jbd2_debug);
>> +EXPORT_SYMBOL(jbd2_log);
>> #endif
>>
>> /* Checksumming functions */
>> @@ -1257,6 +1249,48 @@ static int jbd2_seq_info_release(struct inode *inode, struct file *file)
>> return seq_release(inode, file);
>> }
>>
>> +#ifdef CONFIG_JBD2_DEBUG
>> +static int jbd2_proc_debug_show(struct seq_file *m, void *v)
>> +{
>> + journal_t *j = m->private;
>> +
>> + seq_printf(m, "%d\n", j->j_debug_level);
>> + return 0;
>> +}
>> +
>> +static int jbd2_proc_debug_open(struct inode *inode, struct file *file)
>> +{
>> + journal_t *journal = PDE_DATA(inode);
>> +
>> + return single_open(file, jbd2_proc_debug_show, journal);
>> +}
>> +
>> +static ssize_t jbd2_proc_debug_write(struct file *file,
>> + const char __user *buffer, size_t count, loff_t *ppos)
>> +{
>> + struct seq_file *seq = file->private_data;
>> + journal_t *j = seq->private;
>> + char c;
>> +
>> + if (get_user(c, buffer))
>> + return -EFAULT;
>> +
>> + if (c < '0' || c > '5')
>> + return -EINVAL;
>> +
>> + j->j_debug_level = c - '0';
>> + return count;
>> +}
>> +
>> +static const struct proc_ops jbd2_debug_proc_ops = {
>> + .proc_open = jbd2_proc_debug_open,
>> + .proc_read = seq_read,
>> + .proc_write = jbd2_proc_debug_write,
>> + .proc_release = single_release,
>> + .proc_lseek = seq_lseek,
>> +};
>> +#endif
>> +
>> static const struct proc_ops jbd2_info_proc_ops = {
>> .proc_open = jbd2_seq_info_open,
>> .proc_read = seq_read,
>> @@ -1272,12 +1306,19 @@ static void jbd2_stats_proc_init(journal_t *journal)
>> if (journal->j_proc_entry) {
>> proc_create_data("info", S_IRUGO, journal->j_proc_entry,
>> &jbd2_info_proc_ops, journal);
>> +#ifdef CONFIG_JBD2_DEBUG
>> + proc_create_data("jbd2_debug", S_IRUGO, journal->j_proc_entry,
>> + &jbd2_debug_proc_ops, journal);
>> +#endif
>> }
>> }
>>
>> static void jbd2_stats_proc_exit(journal_t *journal)
>> {
>> remove_proc_entry("info", journal->j_proc_entry);
>> +#ifdef CONFIG_JBD2_DEBUG
>> + remove_proc_entry("jbd2_debug", journal->j_proc_entry);
>> +#endif
>> remove_proc_entry(journal->j_devname, proc_jbd2_stats);
>> }
>>
>> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
>> index 9396666b7314..f25c6ff16165 100644
>> --- a/fs/jbd2/transaction.c
>> +++ b/fs/jbd2/transaction.c
>> @@ -150,7 +150,7 @@ static inline void update_t_max_wait(transaction_t *transaction,
>> unsigned long ts)
>> {
>> #ifdef CONFIG_JBD2_DEBUG
>> - if (jbd2_journal_enable_debug &&
>> + if (transaction->t_journal->j_debug_level &&
>> time_after(transaction->t_start, ts)) {
>> ts = jbd2_time_diff(ts, transaction->t_start);
>> spin_lock(&transaction->t_handle_lock);
>> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
>> index 99d3cd051ac3..600a2ea8324a 100644
>> --- a/include/linux/jbd2.h
>> +++ b/include/linux/jbd2.h
>> @@ -1211,6 +1211,13 @@ struct journal_s
>> */
>> struct transaction_stats_s j_stats;
>>
>> +#ifdef CONFIG_JBD2_DEBUG
>> + /**
>> + * @j_debug_level: debugging level for jbd2.
>> + */
>> + unsigned int j_debug_level;
>> +#endif
>> +
>> /**
>> * @j_failed_commit: Failed journal commit ID.
>> */
>> --
>> 2.30.0
>>
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