orangefs: Fix kmemleak in orangefs_{kernel,client}_debug_init()

When insert and remove the orangefs module, there are memory leaked
as below:

unreferenced object 0xffff88816b0cc000 (size 2048):
  comm "insmod", pid 783, jiffies 4294813439 (age 65.512s)
  hex dump (first 32 bytes):
    6e 6f 6e 65 0a 00 00 00 00 00 00 00 00 00 00 00  none............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<0000000031ab7788>] kmalloc_trace+0x27/0xa0
    [<000000005b405fee>] orangefs_debugfs_init.cold+0xaf/0x17f
    [<00000000e5a0085b>] 0xffffffffa02780f9
    [<000000004232d9f7>] do_one_initcall+0x87/0x2a0
    [<0000000054f22384>] do_init_module+0xdf/0x320
    [<000000003263bdea>] load_module+0x2f98/0x3330
    [<0000000052cd4153>] __do_sys_finit_module+0x113/0x1b0
    [<00000000250ae02b>] do_syscall_64+0x35/0x80
    [<00000000f11c03c7>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

Use the golbal variable as the buffer rather than dynamic allocate to
slove the problem.

Signed-off-by: Zhang Xiaoxu <[email protected]>
Signed-off-by: Mike Marshall <[email protected]>

fs/orangefs/orangefs-debugfs.c

@@ -194,15 +194,10 @@ void orangefs_debugfs_init(int debug_mask)
  */
 static void orangefs_kernel_debug_init(void)
 {
-	int rc = -ENOMEM;
-	char *k_buffer = NULL;
+	static char k_buffer[ORANGEFS_MAX_DEBUG_STRING_LEN] = { };
 
 	gossip_debug(GOSSIP_DEBUGFS_DEBUG, "%s: start\n", __func__);
 
-	k_buffer = kzalloc(ORANGEFS_MAX_DEBUG_STRING_LEN, GFP_KERNEL);
-	if (!k_buffer)
-		goto out;
-
 	if (strlen(kernel_debug_string) + 1 < ORANGEFS_MAX_DEBUG_STRING_LEN) {
 		strcpy(k_buffer, kernel_debug_string);
 		strcat(k_buffer, "\n");
@@ -213,9 +208,6 @@ static void orangefs_kernel_debug_init(void)
 
 	debugfs_create_file(ORANGEFS_KMOD_DEBUG_FILE, 0444, debug_dir, k_buffer,
 			    &kernel_debug_fops);
-
-out:
-	gossip_debug(GOSSIP_DEBUGFS_DEBUG, "%s: rc:%d:\n", __func__, rc);
 }
 
 
@@ -299,18 +291,13 @@ static int help_show(struct seq_file *m, void *v)
 /*
  * initialize the client-debug file.
  */
-static int orangefs_client_debug_init(void)
+static void orangefs_client_debug_init(void)
 {
 
-	int rc = -ENOMEM;
-	char *c_buffer = NULL;
+	static char c_buffer[ORANGEFS_MAX_DEBUG_STRING_LEN] = { };
 
 	gossip_debug(GOSSIP_DEBUGFS_DEBUG, "%s: start\n", __func__);
 
-	c_buffer = kzalloc(ORANGEFS_MAX_DEBUG_STRING_LEN, GFP_KERNEL);
-	if (!c_buffer)
-		goto out;
-
 	if (strlen(client_debug_string) + 1 < ORANGEFS_MAX_DEBUG_STRING_LEN) {
 		strcpy(c_buffer, client_debug_string);
 		strcat(c_buffer, "\n");
@@ -324,13 +311,6 @@ static int orangefs_client_debug_init(void)
 						  debug_dir,
 						  c_buffer,
 						  &kernel_debug_fops);
-
-	rc = 0;
-
-out:
-
-	gossip_debug(GOSSIP_DEBUGFS_DEBUG, "%s: rc:%d:\n", __func__, rc);
-	return rc;
 }
 
 /* open ORANGEFS_KMOD_DEBUG_FILE or ORANGEFS_CLIENT_DEBUG_FILE.*/