Re: [PATCH] autofs: make autofs4 and autofs mutually exclusive

[Arnd Bergmann <arnd@arndb.de>]

On Wed, May 30, 2018 at 2:48 AM, Ian Kent <raven@themaw.net> wrote:
> On Tue, 2018-05-29 at 11:46 +0200, Arnd Bergmann wrote:
>> The autofs4 implementation is just a redirect to autofs now, but that
>> also means we can't have both built into the same kernel:
>>
>> fs/autofs/inode.o: In function `autofs_new_ino':
>> inode.c:(.text+0x1b8): multiple definition of `autofs_new_ino'
>> fs/autofs/inode.o:inode.c:(.text+0x1b8): first defined here
>> fs/autofs/inode.o: In function `autofs_clean_ino':
>> inode.c:(.text+0x288): multiple definition of `autofs_clean_ino'
>>
>> There is also a problem with trying to build both in parallel, which
>> leads to two 'make' processes writing to the same fs/autofs/.*.o.cmd
>> file, causing corruption that manifests like
>>
>> fs/autofs4/../autofs/.expire.o.cmd:679: *** missing separator.  Stop.
>>
>> Making AUTOFS4_FS depend on AUTOFS_FS being disabled should avoid all
>> configurations that run into either issue.
>
> Thanks Arnd and this adds support that my analysis of build
> problems is accurate.
>
> I posted a similar patch on May 21 which also added a NOTE to
> fs/autofs4/Kconfig saying pretty much what you've said.
> https://patchwork.kernel.org/patch/10413823/
>
> I recommend using my patch so that anyone that's surprised by the
> .config change has a chance of finding an explanation somewhere, ;)
>
> Not only is the change needed, but to preserve bisection it needs
> to be folded into the original patch titled:
> autofs: create autofs Kconfig and Makefile
>
> otherwise build test robots will still see this problem between
> build testing after "autofs: create autofs Kconfig and Makefile"
> and before this change is applied.
>
> Folding in the change is my current recommendation to Andrew.
> Hopefully that will fix the problem.

Yes, looks good.

> Any further thoughts are of course welcome.

I actually had an alternative approach that I tried out successfully
but discarded as being too different from the original code. Just for
reference, this one would work as well, and allow both to be
compiled together. The version you posted is probably better.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h
index 9400a9f6318a..5a361f5273a1 100644
--- a/fs/autofs/autofs_i.h
+++ b/fs/autofs/autofs_i.h
@@ -6,6 +6,8 @@
  * the terms of the GNU General Public License, version 2, or at your
  * option, any later version, incorporated herein by reference.
  */
+#ifndef __AUTOFS_H
+#define __AUTOFS_H

 /* Internal header file for autofs */

@@ -271,3 +273,5 @@ static inline void autofs_del_expiring(struct
dentry *dentry)
 }

 void autofs_kill_sb(struct super_block *);
+
+#endif /* __AUTOFS_H */
diff --git a/fs/autofs4/Makefile b/fs/autofs4/Makefile
index 417dd726d9ef..5fc0a28d656d 100644
--- a/fs/autofs4/Makefile
+++ b/fs/autofs4/Makefile
@@ -3,7 +3,3 @@
 #

 obj-$(CONFIG_AUTOFS4_FS) += autofs4.o
-
-autofs4-objs := ../autofs/init.o ../autofs/inode.o ../autofs/root.o \
-       ../autofs/symlink.o ../autofs/waitq.o ../autofs/expire.o \
-       ../autofs/dev-ioctl.o
diff --git a/fs/autofs4/autofs4.c b/fs/autofs4/autofs4.c
new file mode 100644
index 000000000000..a76066aa9f27
--- /dev/null
+++ b/fs/autofs4/autofs4.c
@@ -0,0 +1,7 @@
+#include "../autofs/init.c"
+#include "../autofs/inode.c"
+#include "../autofs/root.c"
+#include "../autofs/symlink.c"
+#include "../autofs/waitq.c"
+#include "../autofs/expire.c"
+#include "../autofs/dev-ioctl.c"