Re: jbd : config_jbd_debug cannot create /proc entry

From: Jan Kara
Date: Tue Sep 25 2007 - 06:52:22 EST


> I enabled config_jbd_debug in the hope that it may help track down the
> lockup I'm seeing, but unfortunately the /proc entry does not get
> created.
>
> any ideas how to fix this ?
Attached is a patch that should fix it. Andrew, would you queue it up?

Honza

JBD debug code used old way of creating proc entries for jbd-debug file.
Change it to use sysctl instead.

Signed-off-by: Jan Kara <jack@xxxxxxx>

diff -rupX /home/jack/.kerndiffexclude linux-2.6.23-rc6/fs/jbd/journal.c linux-2.6.23-rc6-1-jbddebug_fix/fs/jbd/journal.c
--- linux-2.6.23-rc6/fs/jbd/journal.c 2007-09-25 12:39:53.000000000 +0200
+++ linux-2.6.23-rc6-1-jbddebug_fix/fs/jbd/journal.c 2007-09-25 13:05:05.000000000 +0200
@@ -1944,58 +1944,29 @@ void journal_put_journal_head(struct jou
#if defined(CONFIG_JBD_DEBUG)
int journal_enable_debug;
EXPORT_SYMBOL(journal_enable_debug);
-#endif
-
-#if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS)
-
-static struct proc_dir_entry *proc_jbd_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", 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;
-}
+static struct ctl_table_header *jbd_debug_table;

-#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;
- }
-}
-
-static void __exit remove_jbd_proc_entry(void)
-{
- if (proc_jbd_debug)
- remove_proc_entry(JBD_PROC_NAME, NULL);
-}
-
-#else
-
-#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 */
+ .procname = "jbd-debug",
+ .data = &journal_enable_debug,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ { .ctl_name = 0 },
+};
+
+static ctl_table sys_table[] = {
+ {
+ .ctl_name = CTL_FS,
+ .procname = "fs",
+ .mode = 0555,
+ .child = fs_table,
+ },
+ { .ctl_name = 0 },
+};

#endif

@@ -2054,7 +2025,10 @@ static int __init journal_init(void)
ret = journal_init_caches();
if (ret != 0)
journal_destroy_caches();
- create_jbd_proc_entry();
+
+#ifdef CONFIG_JBD_DEBUG
+ jbd_debug_table = register_sysctl_table(sys_table);
+#endif
return ret;
}

@@ -2064,8 +2038,8 @@ static void __exit journal_exit(void)
int n = atomic_read(&nr_journal_heads);
if (n)
printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
+ unregister_sysctl_table(jbd_debug_table);
#endif
- remove_jbd_proc_entry();
journal_destroy_caches();
}

-
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