Re: [resend PATCH] reserve BLKGETSIZE64 ioctl

[Andries.Brouwer@cwi.nl]

    From: Ben LaHaise <bcrl@redhat.com>

    Is there any problem with the patch below for reserving a 64 bit get block
    device size ioctl?

    +#define BLKBSZGET  _IOR(0x12,110,sizeof(u64))
     #define BLKBSZGET  _IOR(0x12,112,sizeof(int))

Yes.

(1) As you can see you'll only get redefinition complaints.
In other words, there is a B too much in the ioctl name.

(2) We just concluded that 108-111 have been used for various
private purposes. If we avoid 108-111 in all official kernels
then nobody will be surprised if he ever uses some system
utility that uses one of these.
Thus, it is a very bad idea to want to use these again.

(3) Soon we'll all need a BLKGETSIZE64 ioctl, that gives
the size of a block device in bytes. Your proposed ioctl
gave the size in blocks if I recall correctly.
So, if you have to change the name and the number,
you might as well change the definition.

Andries


[We might reserve an area for private use - some ioctl numbers
that are guaranteed never to become part of an official kernel.]