Re: jbd : config_jbd_debug cannot create /proc entry

[Jan Kara]

> On Tue, 25 Sep 2007 07:49:38 -0500
> "Jose R. Santos" <jrs@xxxxxxxxxx> wrote:
> 
> > On Tue, 25 Sep 2007 13:50:46 +0200
> > Jan Kara <jack@xxxxxx> wrote:
> > > > Jan Kara wrote:
> > > > >>
> > > > >-#define create_jbd_proc_entry() do {} while (0)
> > > > >-#define remove_jbd_proc_entry() do {} while (0)
> > > > >+static ctl_table fs_table[] = {
> > > > >+	{
> > > > >+                .ctl_name       = -1,	/* Don't want it */
> > > > 
> > > > 
> > > > 
> > > > shouldn't this be CTL_UNNUMBERED ?
> > >   Oh, it should be. I didn't notice we have this :) Thanks for notifying
> > > me. Attached is a fixed version.
> > 
> > This was fixed in JBD2 by moving the jbd-debug file to debugfs:
> > http://lkml.org/lkml/2007/7/11/334
> > 
> > Since this code is already in the kernel, we should keep it consistent. 
> > 
> 
> OK.  Here's a quick patch to fix this.  Adapted from the JBD2 patch.
> Let me know what you think.
  Looks fine - exactly what I've just done here :).

									Honza

> commit 6cbd2ce05b7504514707ce825170a5d77abf6a6e
> Author: root <root@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> Date:   Thu Jun 14 09:40:09 2007 -0500
> 
>     The jbd-debug file used to be located in /proc/sys/fs/jbd-debug, but
>     create_proc_entry() does not do lookups on file names that are more that one
>     directory deep.  This causes the entry creation to fail and hence, no proc
>     file is created.
>     
>     Instead of fixing this on procfs might as well move the jbd2-debug file to
>     debugfs which would be the preferred location for this kind of tunable.  The
>     new location is now /sys/kernel/debug/jbd/jbd-debug.
>     
>     
>     Signed-off-by: Jose R. Santos <jrs@xxxxxxxxxx>
  You can add Signed-off-by: Jan Kara <jack@xxxxxxx>

> 
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 58a0650..a8937a6 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -219,7 +219,7 @@ config JBD
>  
>  config JBD_DEBUG
>  	bool "JBD (ext3) debugging support"
> -	depends on JBD
> +	depends on JBD && DEBUG_FS
>  	help
>  	  If you are using the ext3 journaled file system (or potentially any
>  	  other file system/device using JBD), this option allows you to
> @@ -228,10 +228,10 @@ config JBD_DEBUG
>  	  debugging output will be turned off.
>  
>  	  If you select Y here, then you will be able to turn on debugging
> -	  with "echo N > /proc/sys/fs/jbd-debug", where N is a number between
> -	  1 and 5, the higher the number, the more debugging output is
> -	  generated.  To turn debugging off again, do
> -	  "echo 0 > /proc/sys/fs/jbd-debug".
> +	  with "echo N > /sys/kernel/debug/jbd/jbd-debug", where N is a 
> +	  number between 1 and 5, the higher the number, the more debugging 
> +	  output is generated.  To turn debugging off again, do
> +	  "echo 0 > /sys/kernel/debug/jbd/jbd-debug".
>  
>  config JBD2
>  	tristate
> diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
> index 06ab3c1..3cad624 100644
> --- a/fs/jbd/journal.c
> +++ b/fs/jbd/journal.c
> @@ -35,6 +35,7 @@
>  #include <linux/kthread.h>
>  #include <linux/poison.h>
>  #include <linux/proc_fs.h>
> +#include <linux/debugfs.h>
>  
>  #include <asm/uaccess.h>
>  #include <asm/page.h>
> @@ -1939,63 +1940,38 @@ void journal_put_journal_head(struct journal_head *jh)
>  }
>  
>  /*
> - * /proc tunables
> + * debugfs tunables
>   */
>  #if defined(CONFIG_JBD_DEBUG)
> -int journal_enable_debug;
> +u8 journal_enable_debug;
>  EXPORT_SYMBOL(journal_enable_debug);
>  #endif
>  
> -#if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS)
> +#if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_DEBUG_FS)
>  
> -static struct proc_dir_entry *proc_jbd_debug;
> +struct dentry  *jbd_debugfs_dir, *jbd_debug;
>  
> -static int read_jbd_debug(char *page, char **start, off_t off,
> -			  int count, int *eof, void *data)
> +static void __init create_jbd_debugfs_entry(void)
>  {
> -	int ret;
> -
> -	ret = sprintf(page + off, "%d\n", journal_enable_debug);
> -	*eof = 1;
> -	return ret;
> -}
> -
> -static int write_jbd_debug(struct file *file, const char __user *buffer,
> -			   unsigned long count, void *data)
> -{
> -	char buf[32];
> -
> -	if (count > ARRAY_SIZE(buf) - 1)
> -		count = ARRAY_SIZE(buf) - 1;
> -	if (copy_from_user(buf, buffer, count))
> -		return -EFAULT;
> -	buf[ARRAY_SIZE(buf) - 1] = '\0';
> -	journal_enable_debug = simple_strtoul(buf, NULL, 10);
> -	return count;
> -}
> -
> -#define JBD_PROC_NAME "sys/fs/jbd-debug"
> -
> -static void __init create_jbd_proc_entry(void)
> -{
> -	proc_jbd_debug = create_proc_entry(JBD_PROC_NAME, 0644, NULL);
> -	if (proc_jbd_debug) {
> -		/* Why is this so hard? */
> -		proc_jbd_debug->read_proc = read_jbd_debug;
> -		proc_jbd_debug->write_proc = write_jbd_debug;
> -	}
> +	jbd_debugfs_dir = debugfs_create_dir("jbd", NULL);
> +	if (jbd_debugfs_dir)
> +		jbd_debug = debugfs_create_u8("jbd-debug", S_IRUGO,
> +					       jbd_debugfs_dir,
> +					       &journal_enable_debug);
>  }
>  
> -static void __exit remove_jbd_proc_entry(void)
> +static void __exit remove_jbd_debugfs_entry(void)
>  {
> -	if (proc_jbd_debug)
> -		remove_proc_entry(JBD_PROC_NAME, NULL);
> +	if (jbd_debug)
> +		debugfs_remove(jbd_debug);
> +	if (jbd_debugfs_dir)
> +		debugfs_remove(jbd_debugfs_dir);
>  }
>  
>  #else
>  
> -#define create_jbd_proc_entry() do {} while (0)
> -#define remove_jbd_proc_entry() do {} while (0)
> +#define create_jbd_debugfs_entry() do {} while (0)
> +#define remove_jbd_debugfs_entry() do {} while (0)
>  
>  #endif
>  
> @@ -2054,7 +2030,7 @@ static int __init journal_init(void)
>  	ret = journal_init_caches();
>  	if (ret != 0)
>  		journal_destroy_caches();
> -	create_jbd_proc_entry();
> +	create_jbd_debugfs_entry();
>  	return ret;
>  }
>  
> @@ -2065,7 +2041,7 @@ static void __exit journal_exit(void)
>  	if (n)
>  		printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
>  #endif
> -	remove_jbd_proc_entry();
> +	remove_jbd_debugfs_entry();
>  	journal_destroy_caches();
>  }
>  
> diff --git a/include/linux/jbd.h b/include/linux/jbd.h
> index 4527375..526548d 100644
> --- a/include/linux/jbd.h
> +++ b/include/linux/jbd.h
> @@ -57,7 +57,7 @@
>   * CONFIG_JBD_DEBUG is on.
>   */
>  #define JBD_EXPENSIVE_CHECKING
> -extern int journal_enable_debug;
> +extern u8 journal_enable_debug;
>  
>  #define jbd_debug(n, f, a...)						\
>  	do {								\
-- 
Jan Kara <jack@xxxxxxx>
SuSE CR Labs
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