Miklos Szeredi [off-list ref] writes:

On Wed, 8 Jul 2026 at 14:27, Giuseppe Scrivano [off-list ref] wrote:

quoted

is there any existing user of such a mechanism?  I don't see any mount
specific info under /proc or /sys.

Not yet, but I think it would be good to have one.  It's definitely a
bigger bite than adding an ioctl(), though.

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OVL_IOC_GET_LAYERS_INFO: copy a struct ovl_layers_info to userspace
                        with numlower, numlowerdata, and has_upper.

Isn't this info obtainable via statmount(2) already?  If not, it
should be there, instead of a specialized ioctl.

quoted

no that is not exposed by statmount

I mean, you should be able to get that info by counting the lowerdir+,
datadir+ and upperdir options, no?

Amir suggested to add that functionality when I've asked for some
feedback before sending the patch here.  I am fine to drop it if this is
the consensus although I see its utility from user space.

Regards,
Giuseppe