On Fri, Jan 29, 2016 at 07:56:44PM -0500, Pranith Kumar wrote:

This commit breaks building latest qemu as follows:

Well, this commit moves where the fsxattr struct is around, but the
header files that gcc is complaining about here:

In file included from /usr/include/xfs/xfs.h:58:0,
                 from /home/pranith/qemu/block/raw-posix.c:96:
/usr/include/xfs/xfs_fs.h:42:8: error: redefinition of ‘struct fsxattr’
 struct fsxattr {
        ^
In file included from /home/pranith/qemu/block/raw-posix.c:59:0:
/usr/include/linux/fs.h:155:8: note: originally defined here
 struct fsxattr {
        ^
/home/pranith/qemu/rules.mak:57: recipe for target 'block/raw-posix.o' failed

are userspace header files in /usr/include, and so the problem isn't
in the kernel, but how the userspace header files have been set up.

You didn't say what distribution you are using, but I suspect what's
going on is that you are getting /usr/include/xfs/xfs_fs.h from the
xfsprogs package, while the /usr/include/linux/fs.h is getting derived
from the include/uapi/linux/fs.h file from the kernel header files.

So the issue is that these two header files are out of sync.  It's
because of issues like this that I'm not a fan of updating the kernel
header files whenever I install a newer kernel version.

So on my Debain system, I don't update linux-libc-dev when I install a
new upstream kernel built using "make deb-pkg".  I'll still a new
version of the linux-image-*.deb file, and maybe a newer version of
linux-firmware-*.dev, but I don't bother installing the
linux-headers-*.deb file (since I don't compile external kernel
modules), and I don't bother installing linux-libc-dev-*.deb (because
of situations like this, where the userspace include files need ot be
updated in sync, and this should be the distribution's problem to
handle).

Cheers,

						- Ted