Re: [PATCH] ocfs2: fix panic due to ocfs2_wq is null

[Joseph Qi]

On 19/10/15 17:05, Yi Li wrote:
> mount.ocfs2 failed when read ocfs2 filesystem super error.
> the func ocfs2_initialize_super will return before allocate ocfs2_wq.
> ocfs2_dismount_volume will flush the ocfs2_wq, that triggered the following panic.
> 
> Oct 15 16:09:27 cnwarekv-205120 kernel: OCFS2: ERROR (device dm-34): ocfs2_validate_inode_block: Invalid dinode #513: fs_generation is 1837764116
> Oct 15 16:09:27 cnwarekv-205120 kernel: On-disk corruption discovered. Please run fsck.ocfs2 once the filesystem is unmounted.
> Oct 15 16:09:27 cnwarekv-205120 kernel: OCFS2: File system is now read-only.
> Oct 15 16:09:27 cnwarekv-205120 kernel: (mount.ocfs2,22804,44):ocfs2_read_locked_inode:537 ERROR: status = -30
> Oct 15 16:09:27 cnwarekv-205120 kernel: (mount.ocfs2,22804,44):ocfs2_init_global_system_inodes:458 ERROR: status = -30
> Oct 15 16:09:27 cnwarekv-205120 kernel: (mount.ocfs2,22804,44):ocfs2_init_global_system_inodes:491 ERROR: status = -30
> Oct 15 16:09:27 cnwarekv-205120 kernel: (mount.ocfs2,22804,44):ocfs2_initialize_super:2313 ERROR: status = -30
> Oct 15 16:09:27 cnwarekv-205120 kernel: (mount.ocfs2,22804,44):ocfs2_fill_super:1033 ERROR: status = -30
> ------------[ cut here ]------------
> Oops: 0002 [#1] SMP NOPTI
> Modules linked in: ocfs2 rpcsec_gss_krb5 auth_rpcgss nfsv4 nfs fscache lockd grace ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue configfs sunrpc ipt_REJECT nf_reject_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 iptable_filter ip_tables ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables ib_ipoib rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr ipv6 ovmapi ppdev parport_pc parport xen_netfront fb_sys_fops sysimgblt sysfillrect syscopyarea acpi_cpufreq pcspkr i2c_piix4 i2c_core sg ext4 jbd2 mbcache2 sr_mod cdrom xen_blkfront pata_acpi ata_generic ata_piix floppy dm_mirror dm_region_hash dm_log dm_mod
> CPU: 1 PID: 11753 Comm: mount.ocfs2 Tainted: G  E	4.14.148-200.ckv.x86_64 #1
> Hardware name: Sugon H320-G30/35N16-US, BIOS 0SSDX017 12/21/2018
> task: ffff967af0520000 task.stack: ffffa5f05484000
> RIP: 0010:mutex_lock+0x19/0x20
> Call Trace:
>   flush_workqueue+0x81/0x460
>   ocfs2_shutdown_local_alloc+0x47/0x440 [ocfs2]
>   ocfs2_dismount_volume+0x84/0x400 [ocfs2]
>   ocfs2_fill_super+0xa4/0x1270 [ocfs2]
>   ? ocfs2_initialize_super.isa.211+0xf20/0xf20 [ocfs2]
>   mount_bdev+0x17f/0x1c0
>   mount_fs+0x3a/0x160
> 
> Signed-off-by: Yi Li <yilikernel@xxxxxxxxx>
> ---
>  fs/ocfs2/localalloc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
> index 158e5af..943e5c3 100644
> --- a/fs/ocfs2/localalloc.c
> +++ b/fs/ocfs2/localalloc.c
> @@ -377,7 +377,9 @@ void ocfs2_shutdown_local_alloc(struct ocfs2_super *osb)
>  	struct ocfs2_dinode *alloc = NULL;
>  
>  	cancel_delayed_work(&osb->la_enable_wq);
> -	flush_workqueue(osb->ocfs2_wq);
> +	if (osb->ocfs2_wq) {
> +	    flush_workqueue(osb->ocfs2_wq);
> +	}

No need braces here.
I think this fix is not enough since ocfs2_recovery_exit() will also
do flush_workqueue().

Thanks,
Joseph

>  
>  	if (osb->local_alloc_state == OCFS2_LA_UNUSED)
>  		goto out;
>