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Li Zhijian 7c0950d455 initramfs: clean old path before creating a hardlink
sys_link() can fail due to the new path already existing.  This case
ofen occurs when we use a concated initrd, for example:

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

[akpm@linux-foundation.org: move code to avoid forward declaration]
Link: http://lkml.kernel.org/r/1542352368-13299-1-git-send-email-lizhijian@cn.fujitsu.com
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Cc: Philip Li <philip.li@intel.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Li Zhijian <zhijianx.li@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-11-30 14:56:14 -08:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-11-30 11:34:25 -08:00
block
certs
crypto
Documentation psi: make disabling/enabling easier for vendor kernels 2018-11-30 14:56:14 -08:00
drivers Char/Misc fixes for 4.20-rc5 2018-11-30 12:43:17 -08:00
firmware
fs userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas 2018-11-30 14:56:14 -08:00
include psi: make disabling/enabling easier for vendor kernels 2018-11-30 14:56:14 -08:00
init initramfs: clean old path before creating a hardlink 2018-11-30 14:56:14 -08:00
ipc
kernel kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace 2018-11-30 14:56:14 -08:00
lib debugobjects: avoid recursive calls with kmemleak 2018-11-30 14:56:14 -08:00
LICENSES
mm userfaultfd: shmem: UFFDIO_COPY: set the page dirty if VM_WRITE is not set 2018-11-30 14:56:14 -08:00
net
samples
scripts
security
sound
tools proc: fixup map_files test on arm 2018-11-30 14:56:14 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS proc: update MAINTAINERS with proc.txt 2018-11-30 14:56:14 -08:00
Makefile
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.