[PATCH 6.8.y 2/2] erofs: reliably distinguish block based and fscache mode

[Greg Kroah-Hartman]

On Tue, May 21, 2024 at 02:50:32PM +0800, Gao Xiang wrote:
> From: Christian Brauner <brauner at kernel.org>
> 
> commit 7af2ae1b1531feab5d38ec9c8f472dc6cceb4606 upstream.
> 
> 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>
> ---
>  fs/erofs/super.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)

All now queued up, thanks.

greg k-h