[Devel] [PATCH RH7] ve/devmnt: initialize s_mode before deactivate_locked_super to suppress warning

[Kirill Tkhai]

On 18.07.2018 14:40, Pavel Tikhomirov wrote:
> WARNING: CPU: 12 PID: 898592 at fs/super.c:1120 kill_block_super+0x63/0x70
> Call Trace:
> [<ffffffff816a02f8>] dump_stack+0x19/0x1b
> [<ffffffff81088be8>] __warn+0xd8/0x100
> [<ffffffff81088d2d>] warn_slowpath_null+0x1d/0x20
> [<ffffffff8121dfa3>] kill_block_super+0x63/0x70
> [<ffffffffc04891ec>] ext4_kill_sb+0x4c/0x60 [ext4]
> [<ffffffff8121e499>] deactivate_locked_super+0x49/0x80
> [<ffffffff8121efd7>] mount_bdev+0x227/0x240
> [<ffffffffc048f330>] ? ext4_calculate_overhead+0x430/0x430 [ext4]
> [<ffffffffc0489f34>] ext4_mount+0x44/0x60 [ext4]
> [<ffffffff8121fb35>] mount_fs+0x15/0xc0
> [<ffffffff8123c757>] vfs_kern_mount+0x67/0x110
> [<ffffffff8123efb9>] do_mount+0x219/0xae0
> [<ffffffff8123fbc6>] SyS_mount+0x96/0xf0
> [<ffffffff816b1649>] system_call_fastpath+0x16/0x1b
> 
> On 3.10.0-693.1.1.vz7.37.30 kernel.
> 
> We warn on no FMODE_EXCL on super block at kill_block_super. We get
> there from ve_devmnt_process's error path in mount_bdev, here we have
> yet uninitialized sb, thus it's s_mode has no FMODE_EXCL. So lets move
> s_mode initialization before these error path.
> 
> Fixes commit 0759581712eb ("ve/fs/devmnt: process mount options")
> 
> https://jira.sw.ru/browse/PSBM-80743
> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>

> ---
>  fs/super.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/super.c b/fs/super.c
> index ca9bd0d261ba..fcc01a129752 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1147,7 +1147,10 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
>  #ifdef CONFIG_VE
>  		void *data_orig = data;
>  		struct ve_struct *ve = get_exec_env();
> +#endif
>  
> +		s->s_mode = mode;
> +#ifdef CONFIG_VE
>  		if (!ve_is_super(ve)) {
>  			error = ve_devmnt_process(ve, bdev->bd_dev, &data, 0);
>  			if (error) {
> @@ -1156,7 +1159,6 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
>  			}
>  		}
>  #endif
> -		s->s_mode = mode;
>  		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
>  		sb_set_blocksize(s, block_size(bdev));
>  		error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
>