[PATCH 3.16 288/370] btrfs: fix btrfs_compat_ioctl failures on non-compat ioctls

Ben Hutchings
2017-03-10T13:42:40Z

From: Jeff Mahoney <jeffm@suse.com>

commit 2a362249187a8d0f6d942d6e1d763d150a296f47 upstream.

Commit 4c63c2454ef incorrectly assumed that returning -ENOIOCTLCMD would
cause the native ioctl to be called. The ->compat_ioctl callback is
expected to handle all ioctls, not just compat variants. As a result,
when using 32-bit userspace on 64-bit kernels, everything except those
three ioctls would return -ENOTTY.

Fixes: 4c63c2454ef ("btrfs: bugfix: handle FS_IOC32_{GETFLAGS,SETFLAGS,GETVERSION} in btrfs_ioctl")
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/ioctl.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -5536,6 +5536,10 @@ long btrfs_ioctl(struct file *file, unsi
#ifdef CONFIG_COMPAT
long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
+ /*
+ * These all access 32-bit values anyway so no further
+ * handling is necessary.
+ */
switch (cmd) {
case FS_IOC32_GETFLAGS:
cmd = FS_IOC_GETFLAGS;
@@ -5546,8 +5550,6 @@ long btrfs_compat_ioctl(struct file *fil
case FS_IOC32_GETVERSION:
cmd = FS_IOC_GETVERSION;
break;
- default:
- return -ENOIOCTLCMD;
}

return btrfs_ioctl(file, cmd, (unsigned long) compat_ptr(arg));