Re: [RFC PATCH] overlayfs: add OVL_IOC_GETINFOFD ioctl that opens ovlinfofd

On Mon, Oct 5, 2020 at 8:13 PM Alexander Mikhalitsyn
[off-list ref] wrote:

On Mon, 5 Oct 2020 10:08:42 -0700
Randy Dunlap [off-list ref] wrote:

quoted

On 10/5/20 10:02 AM, Alexander Mikhalitsyn wrote:

quoted

 #define    OVL_IOC_GETLWRFHNDLSNUM                 _IO('o', 1)
 // DISCUSS: what if MAX_HANDLE_SZ will change?
 #define    OVL_IOC_GETLWRFHNDL                     _IOR('o', 2, struct ovl_mnt_opt_fh)
 #define    OVL_IOC_GETUPPRFHNDL                    _IOR('o', 3, struct ovl_mnt_opt_fh)
 #define    OVL_IOC_GETWRKFHNDL                     _IOR('o', 4, struct ovl_mnt_opt_fh)
+#define    OVL_IOC_GETINFOFD                       _IO('o', 5)

Hi,

Quoting (repeating) from
https://lore.kernel.org/lkml/9cd0e9d1-f124-3f2d-86e6-e6e96a1ccb1e@infradead.org/ (local):

This needs to have Documentation/userspace-api/ioctl/ioctl-number.rst
updated also.

...

Are you waiting until it's past RFC stage?

thanks.
--
~Randy

Hi,

thank you! I will prepare this change too when we
decide which ioctls to add. ;)

Or... don't do ioctls and avoid the ABI headaches.
If you are going to expose a seqfile I think it would be much prefered
to do a /sys/fs/overlay/instance/<device minor>/layes file.

But that's just my opinion.

Thanks,
Amir.