jbd: config_jbd_debug cannot create /proc entry

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.

[akpm@linux-foundation.org: zillions of cleanups]
Signed-off-by: Jose R. Santos <jrs@us.ibm.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 43 deletions

diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index f810047a719..5d14243499d 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>
@@ -1851,64 +1852,41 @@ void journal_put_journal_head(struct journal_head *jh)
 }
 
 /*
- * /proc tunables
+ * debugfs tunables
  */
-#if defined(CONFIG_JBD_DEBUG)
-int journal_enable_debug;
-EXPORT_SYMBOL(journal_enable_debug);
-#endif
+#ifdef CONFIG_JBD_DEBUG
 
-#if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS)
+u8 journal_enable_debug __read_mostly;
+EXPORT_SYMBOL(journal_enable_debug);
 
-static struct proc_dir_entry *proc_jbd_debug;
+static struct dentry *jbd_debugfs_dir;
+static struct dentry *jbd_debug;
 
-static int read_jbd_debug(char *page, char **start, off_t off,
-			  int count, int *eof, void *data)
+static void __init jbd_create_debugfs_entry(void)
 {
-	int ret;
-
-	ret = sprintf(page + off, "%d\n", journal_enable_debug);
-	*eof = 1;
-	return ret;
+	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 int write_jbd_debug(struct file *file, const char __user *buffer,
-			   unsigned long count, void *data)
+static void __exit jbd_remove_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';
-	journal_enable_debug = simple_strtoul(buf, NULL, 10);
-	return count;
+	debugfs_remove(jbd_debug);
+	debugfs_remove(jbd_debugfs_dir);
 }
 
-#define JBD_PROC_NAME "sys/fs/jbd-debug"
+#else
 
-static void __init create_jbd_proc_entry(void)
+static inline void jbd_create_debugfs_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)
+static inline void jbd_remove_debugfs_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)
-
 #endif
 
 struct kmem_cache *jbd_handle_cache;
@@ -1965,7 +1943,7 @@ static int __init journal_init(void)
 	ret = journal_init_caches();
 	if (ret != 0)
 		journal_destroy_caches();
-	create_jbd_proc_entry();
+	jbd_create_debugfs_entry();
 	return ret;
 }
 
@@ -1976,7 +1954,7 @@ static void __exit journal_exit(void)
 	if (n)
 		printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
 #endif
-	remove_jbd_proc_entry();
+	jbd_remove_debugfs_entry();
 	journal_destroy_caches();
 }