compat-ioctl fix for v5.6

One patch in the compat-ioctl series broke 32-bit rootfs for multiple
people testing on 64-bit kernels. Let's fix it in -rc1 before others
run into the same issue.
compat_ioctl: fix FIONREAD on devices

My final cleanup patch for sys_compat_ioctl() introduced a regression on
the FIONREAD ioctl command, which is used for both regular and special
files, but only works on regular files after my patch, as I had missed
the warning that Al Viro put into a comment right above it.

Change it back so it can work on any file again by moving the implementation
to do_vfs_ioctl() instead.

Fixes: 77b9040195de ("compat_ioctl: simplify the implementation")
Reported-and-tested-by: Christian Zigotzky <>
Reported-and-tested-by: youling257 <>
Signed-off-by: Arnd Bergmann <>
1 file changed