[PATCH resend] compat_ioctl: fix warning caused by qemu

Johannes Stezenbach
2011-07-01T09:33:43Z

On Linux x86_64 host with 32bit userspace, running
qemu or even just "qemu-img create -f qcow2 some.img 1G"
causes a kernel warning:

ioctl32(qemu-img:5296): Unknown cmd fd(3) cmd(00005326){t:'S';sz:0} arg(7fffffff) on some.img
ioctl32(qemu-img:5296): Unknown cmd fd(3) cmd(801c0204){t:02;sz:28} arg(fff77350) on some.img

ioctl 00005326 is CDROM_DRIVE_STATUS,
ioctl 801c0204 is FDGETPRM.

The warning appears because the Linux compat-ioctl handler for these
ioctls only applies to block devices, while qemu also uses the ioctls on
plain files.

Signed-off-by: Johannes Stezenbach <js@sig21.net>
---
(resend with Cc: suggested by get_maintainer.pl)

discussed in http://lkml.kernel.org/r/20110617090424.GA19345@sig21.net

Arnd, is this what you had in mind, or did you mean to move
all floppy compat definitions? I decided to go with the
minimal change. Tested on both 2.6.39.2 and 3.0-rc5-63-g0d72c6f.

diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index cc3eb78..7b72502 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -208,19 +208,6 @@ static int compat_blkpg_ioctl(struct block_device *bdev, fmode_t mode,
#define BLKBSZSET_32 _IOW(0x12, 113, int)
#define BLKGETSIZE64_32 _IOR(0x12, 114, int)

-struct compat_floppy_struct {
- compat_uint_t size;
- compat_uint_t sect;
- compat_uint_t head;
- compat_uint_t track;
- compat_uint_t stretch;
- unsigned char gap;
- unsigned char rate;
- unsigned char spec1;
- unsigned char fmt_gap;
- const compat_caddr_t name;
-};
-
struct compat_floppy_drive_params {
char cmos;
compat_ulong_t max_dtr;
@@ -288,7 +275,6 @@ struct compat_floppy_write_errors {

#define FDSETPRM32 _IOW(2, 0x42, struct compat_floppy_struct)
#define FDDEFPRM32 _IOW(2, 0x43, struct compat_floppy_struct)
-#define FDGETPRM32 _IOR(2, 0x04, struct compat_floppy_struct)
#define FDSETDRVPRM32 _IOW(2, 0x90, struct compat_floppy_drive_params)
#define FDGETDRVPRM32 _IOR(2, 0x11, struct compat_floppy_drive_params)
#define FDGETDRVSTAT32 _IOR(2, 0x12, struct compat_floppy_drive_struct)
diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 61abb63..8be086e 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -68,6 +68,8 @@

#ifdef CONFIG_BLOCK
#include <linux/loop.h>
+#include <linux/cdrom.h>
+#include <linux/fd.h>
#include <scsi/scsi.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/sg.h>
@@ -944,6 +946,9 @@ COMPATIBLE_IOCTL(FIOQSIZE)
IGNORE_IOCTL(LOOP_CLR_FD)
/* md calls this on random blockdevs */
IGNORE_IOCTL(RAID_VERSION)
+/* qemu/qemu-img might call these two on plain files for probing */
+IGNORE_IOCTL(CDROM_DRIVE_STATUS)
+IGNORE_IOCTL(FDGETPRM32)
/* SG stuff */
COMPATIBLE_IOCTL(SG_SET_TIMEOUT)
COMPATIBLE_IOCTL(SG_GET_TIMEOUT)
diff --git a/include/linux/fd.h b/include/linux/fd.h
index f5d194a..c6a68d0 100644
--- a/include/linux/fd.h
+++ b/include/linux/fd.h
@@ -3,6 +3,7 @@

#include <linux/ioctl.h>
#include <linux/compiler.h>
+#include <linux/compat.h>

/* New file layout: Now the ioctl definitions immediately follow the
* definitions of the structures that they use */
@@ -377,4 +378,21 @@ struct floppy_raw_cmd {
#define FDEJECT _IO(2, 0x5a)
/* eject the disk */

+#ifdef CONFIG_COMPAT
+struct compat_floppy_struct {
+ compat_uint_t size;
+ compat_uint_t sect;
+ compat_uint_t head;
+ compat_uint_t track;
+ compat_uint_t stretch;
+ unsigned char gap;
+ unsigned char rate;
+ unsigned char spec1;
+ unsigned char fmt_gap;
+ const compat_caddr_t name;
+};
+
+#define FDGETPRM32 _IOR(2, 0x04, struct compat_floppy_struct)
+#endif
+
#endif