On 2/5/24 17:39, David Sterba wrote:
> On Mon, Feb 05, 2024 at 05:43:37PM -0500, Kent Overstreet wrote:
>> On Mon, Feb 05, 2024 at 02:27:32PM -0800, Darrick J. Wong wrote:
>>> On Mon, Feb 05, 2024 at 03:05:15PM -0500, Kent Overstreet wrote:
>>>> @@ -231,6 +235,7 @@ struct fsxattr {
>>>> #define FS_IOC_SETFSLABEL _IOW(0x94, 50, char[FSLABEL_MAX])
>>>> #define FS_IOC_GETFSUUID _IOR(0x94, 51, struct fsuuid2)
>>>> #define FS_IOC_SETFSUUID _IOW(0x94, 52, struct fsuuid2)
>>>> +#define FS_IOC_GETFSSYSFSNAME _IOR(0x94, 53, struct fssysfsname)
>>>
>>> 0x94 is btrfs, don't add things to their "name" space.
>>
>> Can we please document this somewhere!?
>>
>> What, dare I ask, is the "namespace" I should be using?
>
> Grep for _IOCTL_MAGIC in include/uapi:
>
> uapi/linux/aspeed-lpc-ctrl.h:#define __ASPEED_LPC_CTRL_IOCTL_MAGIC 0xb2
> uapi/linux/aspeed-p2a-ctrl.h:#define __ASPEED_P2A_CTRL_IOCTL_MAGIC 0xb3
> uapi/linux/bt-bmc.h:#define __BT_BMC_IOCTL_MAGIC 0xb1
> uapi/linux/btrfs.h:#define BTRFS_IOCTL_MAGIC 0x94
> uapi/linux/f2fs.h:#define F2FS_IOCTL_MAGIC 0xf5
> uapi/linux/ipmi_bmc.h:#define __IPMI_BMC_IOCTL_MAGIC 0xB1
> uapi/linux/pfrut.h:#define PFRUT_IOCTL_MAGIC 0xEE
> uapi/rdma/rdma_user_ioctl.h:#define IB_IOCTL_MAGIC RDMA_IOCTL_MAGIC
> uapi/rdma/rdma_user_ioctl_cmds.h:#define RDMA_IOCTL_MAGIC 0x1b
>
> The label ioctls inherited the 0x94 namespace for backward
> compatibility but as already said, it's the private namespace of btrfs.
>
or more generally, see Documentation/userspace-api/ioctl/ioctl-number.rst.
For 0x94, it says:
0x94 all fs/btrfs/ioctl.h Btrfs filesystem
and linux/fs.h some lifted to vfs/generic
--
#Randy
