On Thu, 23 Jul 2009, Andi Kleen wrote:
> What I find more suspicious is that it's the direct network
> data structure. Presumably that's in a defined endian?
> So that means the application would already need to
> change to network endian order at the ioctl level?
>
> That seems wrong if true. I think defining
> a ioctl directly based on a network protocol header is
> likely a bad idea.
That's a good point. I've defined an ioctl-specific struct, so the entire
interface is defined in the header:
---
#include <linux/ioctl.h>
#include <linux/types.h>
#define CEPH_IOCTL_MAGIC 0x97
/* just use u64 to align sanely on all archs */
struct ceph_ioctl_layout {
__u64 stripe_unit, stripe_count, object_size;
__u64 data_pool;
};
#define CEPH_IOC_GET_LAYOUT _IOR(CEPH_IOCTL_MAGIC, 1, \
struct ceph_ioctl_layout)
#define CEPH_IOC_SET_LAYOUT _IOW(CEPH_IOCTL_MAGIC, 2, \
struct ceph_ioctl_layout)
---
The remaining issues are:
- this isn't complete. I haven't made up my mind how to list, describe,
and choose the data pool to store a file in; for now it's ignored.
- where the header should go. I don't see any other file system ioctls in
include/linux other than ext[23]; the rest are all in fs/*.
sage
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