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Message-ID: <20070925143608.GB18758@atrey.karlin.mff.cuni.cz>
Date: Tue, 25 Sep 2007 16:36:08 +0200
From: Jan Kara <jack@...e.cz>
To: "Jose R. Santos" <jrs@...ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
richard kennedy <richard@....demon.co.uk>, sct@...hat.com,
akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
linux-ext4@...r.kernel.org
Subject: Re: jbd : config_jbd_debug cannot create /proc entry
> On Tue, 25 Sep 2007 07:49:38 -0500
> "Jose R. Santos" <jrs@...ibm.com> wrote:
>
> > On Tue, 25 Sep 2007 13:50:46 +0200
> > Jan Kara <jack@....cz> 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@...lssf2.ltc.austin.ibm.com>
> 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@...ibm.com>
You can add Signed-off-by: Jan Kara <jack@...e.cz>
>
> 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@...e.cz>
SuSE CR Labs
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