[PATCH AUTOSEL 6.6 21/43] erofs: reliably distinguish block based and fscache mode

[Gao Xiang]

Hi,

On 2024/5/8 07:09, Sasha Levin wrote:
> From: Christian Brauner <brauner at kernel.org>
> 
> [ Upstream commit 7af2ae1b1531feab5d38ec9c8f472dc6cceb4606 ]
> 
> When erofs_kill_sb() is called in block dev based mode, s_bdev may not
> have been initialised yet, and if CONFIG_EROFS_FS_ONDEMAND is enabled,
> it will be mistaken for fscache mode, and then attempt to free an anon_dev
> that has never been allocated, triggering the following warning:
> 
> ============================================
> ida_free called for id=0 which is not allocated.
> WARNING: CPU: 14 PID: 926 at lib/idr.c:525 ida_free+0x134/0x140
> Modules linked in:
> CPU: 14 PID: 926 Comm: mount Not tainted 6.9.0-rc3-dirty #630
> RIP: 0010:ida_free+0x134/0x140
> Call Trace:
>   <TASK>
>   erofs_kill_sb+0x81/0x90
>   deactivate_locked_super+0x35/0x80
>   get_tree_bdev+0x136/0x1e0
>   vfs_get_tree+0x2c/0xf0
>   do_new_mount+0x190/0x2f0
>   [...]
> ============================================
> 
> Now when erofs_kill_sb() is called, erofs_sb_info must have been
> initialised, so use sbi->fsid to distinguish between the two modes.
> 
> Signed-off-by: Christian Brauner <brauner at kernel.org>
> Signed-off-by: Baokun Li <libaokun1 at huawei.com>
> Reviewed-by: Jingbo Xu <jefflexu at linux.alibaba.com>
> Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> Reviewed-by: Chao Yu <chao at kernel.org>
> Link: https://lore.kernel.org/r/20240419123611.947084-3-libaokun1@huawei.com
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> Signed-off-by: Sasha Levin <sashal at kernel.org>

Please help drop this patch, you should backport the dependency
commit 07abe43a28b2 ("erofs: get rid of erofs_fs_context")

in advance.

Thanks,
Gao Xiang