[PATCH] fs: Add MODULE_SOFTDEP declarations for hard-coded crypto drivers

[Mathieu Malaterre <malat@debian.org>]

This helps initramfs builders and other tools to find the full
dependencies of a module.

Debian on powerpc (ppc32) still uses yaboot as default boot loader. Using a
default installation (debian-installer) 64bit and metadata_csum feature are
not setup in ext4. This is discussed in more details at:

https://bugs.debian.org/825110#81

and implemented here:

https://anonscm.debian.org/cgit/d-i/partman-ext3.git/patch/?id=f87dc92157262de1ad8dd3f2343436f08271b4dc

This means that building the kernel as default debian package:

  make ARCH=powerpc XYZ_defconfig
  make -j8 ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnu- bindeb-pkg

Will lead to the following boot failure (initramfs prompt):

  /dev/sda3: clean, 127679/305216 files, 11128559/1220703 blocks done.
  [    5.592819] EXT4-fs (sda3): Cannot load crc32c driver.
  mount: mounting /dev/sda3 on /root failed: No such file or directory

Link: https://bugs.debian.org/819725
Link: https://salsa.debian.org/kernel-team/linux/blob/master/debian/patches/bugfix/all/fs-add-module_softdep-declarations-for-hard-coded-cr.patch
Suggested-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Milan Kupcevic <milan@debian.org>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
---
 fs/ext4/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 185f7e61f4cf..10bda040e78f 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5886,5 +5886,6 @@ static void __exit ext4_exit_fs(void)
 MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
 MODULE_DESCRIPTION("Fourth Extended Filesystem");
 MODULE_LICENSE("GPL");
+MODULE_SOFTDEP("pre: crypto-crc32c");
 module_init(ext4_init_fs)
 module_exit(ext4_exit_fs)
-- 
2.11.0