Re: [PATCH][RFC] JBD2: Use DebugFS for jbd2 debug config option.

[Mingming Cao <cmm@us.ibm.com>]

On Fri, 2007-06-08 at 22:57 -0500, Jose R. Santos wrote:
> On Fri, 8 Jun 2007 01:08:12 -0600
> Andreas Dilger <adilger@clusterfs.com> wrote:
> 
> > On Jun 07, 2007  23:45 -0500, Jose R. Santos wrote:
> > > The jbd2-debug file used to be located in /proc/sys/fs/jbd2-debug, but
> > > create_proc_entry() does not do lookups on file names with more that one
> > > directory deep.  This causes the entry creation to fail and hence, no proc
> > > file is created.  This patch moves the file to /proc/jbd2-degug.
> > > 
> > > The file could be move to /proc/fs/jbd2/jbd2-debug, but it would require
> > > some minor alterations to the jbd-stats patch.
> > 
> > I don't think we really want to be adding top-level files in /proc.
> > What about using the "debugfs" filesystem (not to be confused with
> > the e2fsprogs 'debugfs' command)?
> 
> How about this then?  Moved the file to use debugfs as well as having
> the nice effect of removing more lines than what it adds.
> 
Shall we do this for ext3 as well?

Mingming
> Signed-off-by: Jose R. Santos <jrs@us.ibm.com>
> ---
>  fs/jbd2/journal.c    |   62    20 +    42 -    0 !
>  include/linux/jbd2.h |    2    1 +     1 -     0 !
>  2 files changed, 21 insertions(+), 43 deletions(-)
> 
> Index: linux-2.6.22-rc4/fs/jbd2/journal.c
> ===================================================================
> --- linux-2.6.22-rc4.orig/fs/jbd2/journal.c	2007-06-08 15:03:14.353372404 -0500
> +++ linux-2.6.22-rc4/fs/jbd2/journal.c	2007-06-08 22:44:04.476375738 -0500
> @@ -36,6 +36,7 @@
>  #include <linux/poison.h>
>  #include <linux/proc_fs.h>
>  #include <linux/seq_file.h>
> +#include <linux/debugfs.h>
> 
>  #include <asm/uaccess.h>
>  #include <asm/page.h>
> @@ -2256,60 +2257,37 @@ void jbd2_journal_put_journal_head(struc
>   * /proc tunables
>   */
>  #if defined(CONFIG_JBD2_DEBUG)
> -int jbd2_journal_enable_debug;
> +u16 jbd2_journal_enable_debug;
>  EXPORT_SYMBOL(jbd2_journal_enable_debug);
>  #endif
> 
> -#if defined(CONFIG_JBD2_DEBUG) && defined(CONFIG_PROC_FS)
> +#if defined(CONFIG_JBD2_DEBUG) && defined(CONFIG_DEBUG_FS)
> 
> -static struct proc_dir_entry *proc_jbd_debug;
> +#define JBD2_DEBUG_NAME "jbd2-debug"
> 
> -static int read_jbd_debug(char *page, char **start, off_t off,
> -			  int count, int *eof, void *data)
> -{
> -	int ret;
> -
> -	ret = sprintf(page + off, "%d\n", jbd2_journal_enable_debug);
> -	*eof = 1;
> -	return ret;
> -}
> +struct dentry *jbd2_debugfs_dir, *jbd2_debug;
> 
> -static int write_jbd_debug(struct file *file, const char __user *buffer,
> -			   unsigned long count, void *data)
> +static void __init jbd2_create_debugfs_entry(void)
>  {
> -	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';
> -	jbd2_journal_enable_debug = simple_strtoul(buf, NULL, 10);
> -	return count;
> -}
> -
> -#define JBD_PROC_NAME "sys/fs/jbd2-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;
> -	}
> +	jbd2_debugfs_dir = debugfs_create_dir("jbd2", NULL);
> +	if (jbd2_debugfs_dir)
> +		jbd2_debug = debugfs_create_u16(JBD2_DEBUG_NAME, S_IRUGO,
> +						jbd2_debugfs_dir,
> +						&jbd2_journal_enable_debug);
>  }
> 
> -static void __exit jbd2_remove_jbd_proc_entry(void)
> +static void __exit jbd2_remove_debugfs_entry(void)
>  {
> -	if (proc_jbd_debug)
> -		remove_proc_entry(JBD_PROC_NAME, NULL);
> +	if (jbd2_debug)
> +		debugfs_remove(jbd2_debug);
> +	if (jbd2_debugfs_dir)
> +		debugfs_remove(jbd2_debugfs_dir);
>  }
> 
>  #else
> 
> -#define create_jbd_proc_entry() do {} while (0)
> -#define jbd2_remove_jbd_proc_entry() do {} while (0)
> +#define jbd2_create_debugfs_entry() do {} while (0)
> +#define jbd2_remove_debugfs_entry() do {} while (0)
> 
>  #endif
> 
> @@ -2391,7 +2369,7 @@ static int __init journal_init(void)
>  	ret = journal_init_caches();
>  	if (ret != 0)
>  		jbd2_journal_destroy_caches();
> -	create_jbd_proc_entry();
> +	jbd2_create_debugfs_entry();
>  	jbd2_create_jbd_stats_proc_entry();
>  	return ret;
>  }
> @@ -2403,7 +2381,7 @@ static void __exit journal_exit(void)
>  	if (n)
>  		printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
>  #endif
> -	jbd2_remove_jbd_proc_entry();
> +	jbd2_remove_debugfs_entry();
>  	jbd2_remove_jbd_stats_proc_entry();
>  	jbd2_journal_destroy_caches();
>  }
> Index: linux-2.6.22-rc4/include/linux/jbd2.h
> ===================================================================
> --- linux-2.6.22-rc4.orig/include/linux/jbd2.h	2007-06-08 18:01:41.027527067 -0500
> +++ linux-2.6.22-rc4/include/linux/jbd2.h	2007-06-08 18:02:27.351010026 -0500
> @@ -57,7 +57,7 @@
>   * CONFIG_JBD2_DEBUG is on.
>   */
>  #define JBD_EXPENSIVE_CHECKING
> -extern int jbd2_journal_enable_debug;
> +extern u16 jbd2_journal_enable_debug;
> 
>  #define jbd_debug(n, f, a...)						\
>  	do {								\
> 
> 
> 
> -JRS
> -
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