From 1eb8d7387908022951792a46fa040ad3942b3b08 Mon Sep 17 00:00:00 2001
From: Tim Smith <tim.smith@citrix.com>
Date: Mon, 8 Oct 2018 12:15:40 -0500
Subject: [PATCH] GFS2: Flush the GFS2 delete workqueue before stopping the
kernel threads
Git-commit: 1eb8d7387908022951792a46fa040ad3942b3b08
Patch-mainline: v4.20-rc1
References: git-fixes
Flushing the workqueue can cause operations to happen which might
call gfs2_log_reserve(), or get stuck waiting for locks taken by such
operations. gfs2_log_reserve() can io_schedule(). If this happens, it
will never wake because the only thing which can wake it is gfs2_logd()
which was already stopped.
This causes umount of a gfs2 filesystem to wedge permanently if, for
example, the umount immediately follows a large delete operation.
When this occured, the following stack trace was obtained from the
umount command
[<ffffffff81087968>] flush_workqueue+0x1c8/0x520
[<ffffffffa0666e29>] gfs2_make_fs_ro+0x69/0x160 [gfs2]
[<ffffffffa0667279>] gfs2_put_super+0xa9/0x1c0 [gfs2]
[<ffffffff811b7edf>] generic_shutdown_super+0x6f/0x100
[<ffffffff811b7ff7>] kill_block_super+0x27/0x70
[<ffffffffa0656a71>] gfs2_kill_sb+0x71/0x80 [gfs2]
[<ffffffff811b792b>] deactivate_locked_super+0x3b/0x70
[<ffffffff811b79b9>] deactivate_super+0x59/0x60
[<ffffffff811d2998>] cleanup_mnt+0x58/0x80
[<ffffffff811d2a12>] __cleanup_mnt+0x12/0x20
[<ffffffff8108c87d>] task_work_run+0x7d/0xa0
[<ffffffff8106d7d9>] exit_to_usermode_loop+0x73/0x98
[<ffffffff81003961>] syscall_return_slowpath+0x41/0x50
[<ffffffff815a594c>] int_ret_from_sys_call+0x25/0x8f
[<ffffffffffffffff>] 0xffffffffffffffff
Signed-off-by: Tim Smith <tim.smith@citrix.com>
Signed-off-by: Mark Syms <mark.syms@citrix.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
fs/gfs2/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index c212893534ed..a971862b186e 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -854,10 +854,10 @@ static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
if (error && !test_bit(SDF_SHUTDOWN, &sdp->sd_flags))
return error;
+ flush_workqueue(gfs2_delete_workqueue);
kthread_stop(sdp->sd_quotad_process);
kthread_stop(sdp->sd_logd_process);
- flush_workqueue(gfs2_delete_workqueue);
gfs2_quota_sync(sdp->sd_vfs, 0);
gfs2_statfs_sync(sdp->sd_vfs, 0);
--
2.43.0