AOSP: erofs-utils: fix sub-directory prefix for canned fs_config

"failed to find [%s] in canned fs_config" was observed by using
"--fs-config-file" option as reported by Yue Hu [1].

The root cause was that the mountpoint prefix to subdirectories is
also needed if "--mount-point" presents. However, such prefix cannot
be added by just using erofs_fspath().

One exception is that the root directory itself needs to be handled
specially for canned fs_config. For such case, the prefix of the root
directory has to be dropped instead.

[1] https://lkml.kernel.org/r/20201222020430.12512-1-zbestahu@gmail.com

Link: https://lore.kernel.org/r/20201228105146.2939914-1-hsiangkao@redhat.com
Fixes: 8a9e8046f170 ("AOSP: erofs-utils: add fs_config support")
Reported-and-tested-by: Yue Hu <huyue2@yulong.com>
Tested-by: Huang Jianan <huangjianan@oppo.com>
Reviewed-by: Li Guifu <bluce.lee@aliyun.com>
Signed-off-by: Gao Xiang <hsiangkao@aol.com>
1 file changed