[PATCH 5.4 088/191] ocfs2: fix the crash due to call ocfs2_get_dlm_debug once less

From: Greg Kroah-Hartman
Date: Tue Jan 07 2020 - 16:24:01 EST

From: Gang He <GHe@xxxxxxxx>

commit b73eba2a867e10b9b4477738677341f3307c07bb upstream.

Because ocfs2_get_dlm_debug() function is called once less here, ocfs2
file system will trigger the system crash, usually after ocfs2 file
system is unmounted.

This system crash is caused by a generic memory corruption, these crash
backtraces are not always the same, for exapmle,

ocfs2: Unmounting device (253,16) on (node 172167785)
general protection fault: 0000 [#1] SMP PTI
CPU: 3 PID: 14107 Comm: fence_legacy Kdump:
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:__kmalloc+0xa5/0x2a0
Code: 00 00 4d 8b 07 65 4d 8b
RSP: 0018:ffffaa1fc094bbe8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: d310a8800d7a3faf RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000dc0 RDI: ffff96e68fc036c0
RBP: d310a8800d7a3faf R08: ffff96e6ffdb10a0 R09: 00000000752e7079
R10: 000000000001c513 R11: 0000000004091041 R12: 0000000000000dc0
R13: 0000000000000039 R14: ffff96e68fc036c0 R15: ffff96e68fc036c0
FS: 00007f699dfba540(0000) GS:ffff96e6ffd80000(0000) knlGS:00000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f3a9d9b768 CR3: 000000002cd1c000 CR4: 00000000000006e0
Call Trace:
ext4_htree_store_dirent+0x35/0x100 [ext4]
htree_dirblock_to_tree+0xea/0x290 [ext4]
ext4_htree_fill_tree+0x1c1/0x2d0 [ext4]
ext4_readdir+0x67c/0x9d0 [ext4]
RIP: 0033:0x7f699d33a9fb

This regression problem was introduced by commit e581595ea29c ("ocfs: no
need to check return value of debugfs_create functions").

Link: http://lkml.kernel.org/r/20191225061501.13587-1-ghe@xxxxxxxx
Fixes: e581595ea29c ("ocfs: no need to check return value of debugfs_create functions")
Signed-off-by: Gang He <ghe@xxxxxxxx>
Acked-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Cc: Mark Fasheh <mark@xxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Changwei Ge <gechangwei@xxxxxxx>
Cc: Gang He <ghe@xxxxxxxx>
Cc: Jun Piao <piaojun@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.3+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/ocfs2/dlmglue.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -3282,6 +3282,7 @@ static void ocfs2_dlm_init_debug(struct

debugfs_create_u32("locking_filter", 0600, osb->osb_debug_root,
+ ocfs2_get_dlm_debug(dlm_debug);

static void ocfs2_dlm_shutdown_debug(struct ocfs2_super *osb)