On Fri, 16 Nov 2018 15:12:48 +0800 Li Zhijian <[email protected]> wrote:
> Previously, sys_link() will fail due to the new path is already existed.
> this case ofen appears when we use a concated initrd, below is an
> sample:
>
> 1) prepare a basic rootfs, it contains a regular files rc.local
> lizhijian@:~/yocto-tiny-i386-2016-04-22$ cat etc/rc.local
> #!/bin/sh
> echo "Running /etc/rc.local..."
> yocto-tiny-i386-2016-04-22$ find . | sed 's,^\./,,' | cpio -o -H newc | gzip
> -n -9 >../rootfs.cgz
>
> 2) create a extra initrd which also includes a etc/rc.local
> lizhijian@:~/lkp-x86_64/etc$ echo "append initrd" >rc.local
> lizhijian@:~/lkp/lkp-x86_64/etc$ cat rc.local
> append initrd
> lizhijian@:~/lkp/lkp-x86_64/etc$ ln rc.local rc.local.hardlink
> append initrd
> lizhijian@:~/lkp/lkp-x86_64/etc$ stat rc.local rc.local.hardlink
> File: 'rc.local'
> Size: 14 Blocks: 8 IO Block: 4096 regular file
> Device: 801h/2049d Inode: 11296086 Links: 2
> Access: (0664/-rw-rw-r--) Uid: ( 1002/lizhijian) Gid: ( 1002/lizhijian)
> Access: 2018-11-15 16:08:28.654464815 +0800
> Modify: 2018-11-15 16:07:57.514903210 +0800
> Change: 2018-11-15 16:08:24.180228872 +0800
> Birth: -
> File: 'rc.local.hardlink'
> Size: 14 Blocks: 8 IO Block: 4096 regular file
> Device: 801h/2049d Inode: 11296086 Links: 2
> Access: (0664/-rw-rw-r--) Uid: ( 1002/lizhijian) Gid: ( 1002/lizhijian)
> Access: 2018-11-15 16:08:28.654464815 +0800
> Modify: 2018-11-15 16:07:57.514903210 +0800
> Change: 2018-11-15 16:08:24.180228872 +0800
> Birth: -
>
> lizhijian@:~/lkp/lkp-x86_64$ find . | sed 's,^\./,,' | cpio -o -H newc | gzip
> -n -9 >../rc-local.cgz
> lizhijian@:~/lkp/lkp-x86_64$ gzip -dc ../rc-local.cgz | cpio -t
> .
> etc
> etc/rc.local.hardlink <<< it will be extracted first at this initrd
> etc/rc.local
>
> 3) concate 2 initrds and boot
> lizhijian@:~/lkp$ cat rootfs.cgz rc-local.cgz >concate-initrd.cgz
> lizhijian@:~/lkp$ qemu-system-x86_64 -nographic -enable-kvm -cpu host -smp 1
> -m 1024 -kernel ~/lkp/linux/arch/x86/boot/bzImage -append "console=ttyS0
> earlyprint=ttyS0 ignore_loglevel" -initrd ./concate-initr.cgz -serial stdio
> -nodefaults
>
> In this case, sys_link(2) will fail and return -EEXIST, so we can only
> get the rc.local at rootfs.cgz instead of rc-local.cgz
I can't claim to understand this, but I believe you ;)
How serious is this problem? Do you think a 4.20 merge is justified?
Or a -stable backport? If so, why?
> --- a/init/initramfs.c
> +++ b/init/initramfs.c
> @@ -291,12 +291,16 @@ static int __init do_reset(void)
> return 1;
> }
>
> +static void __init clean_path(char *path, umode_t fmode);
> +
> static int __init maybe_link(void)
> {
> if (nlink >= 2) {
> char *old = find_link(major, minor, ino, mode, collected);
> - if (old)
> + if (old) {
> + clean_path(collected, 0);
> return (ksys_link(old, collected) < 0) ? -1 : 1;
> + }
> }
> return 0;
> }
The forward declaration is unpleasing. Why not simply move the function?
--- a/init/initramfs.c~initramfs-clean-old-path-before-creating-a-hardlink-fix
+++ a/init/initramfs.c
@@ -291,7 +291,17 @@ static int __init do_reset(void)
return 1;
}
-static void __init clean_path(char *path, umode_t fmode);
+static void __init clean_path(char *path, umode_t fmode)
+{
+ struct kstat st;
+
+ if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
+ if (S_ISDIR(st.mode))
+ ksys_rmdir(path);
+ else
+ ksys_unlink(path);
+ }
+}
static int __init maybe_link(void)
{
@@ -305,18 +315,6 @@ static int __init maybe_link(void)
return 0;
}
-static void __init clean_path(char *path, umode_t fmode)
-{
- struct kstat st;
-
- if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
- if (S_ISDIR(st.mode))
- ksys_rmdir(path);
- else
- ksys_unlink(path);
- }
-}
-
static __initdata int wfd;
static int __init do_name(void)
_
