On Wed, Mar 26, 2025 at 12:56:56PM -0600, Uday Shankar wrote:
> On Wed, Mar 26, 2025 at 11:54:16AM -0600, Uday Shankar wrote:
> > > ublk_abort_requests() should be called only in case of queue dying,
> > > since ublk server may open & close the char device multiple times.
> >
> > Sure that is technically possible, however is any real ublk server doing
> > this? Seems like a strange thing to do, and seems reasonable for the
> > driver to transition the device to the nosrv state (dead or recovery,
> > depending on flags) when the char device is closed, since in this case,
> > no one can be handling I/O anymore.
>
> I see ublksrv itself is doing this :(
>
> /* Wait until ublk device is setup by udev */
> static void ublksrv_check_dev(const struct ublksrv_ctrl_dev_info *info)
> {
> unsigned int max_time = 1000000, wait = 0;
> char buf[64];
>
> snprintf(buf, 64, "%s%d", "/dev/ublkc", info->dev_id);
>
> while (wait < max_time) {
> int fd = open(buf, O_RDWR);
>
> if (fd > 0) {
> close(fd);
> break;
> }
>
> usleep(100000);
> wait += 100000;
> }
> }
>
> This seems related to some failures in ublksrv tests
Actually this is the only issue I'm seeing - after patching this up in
ublksrv, make T=generic test appears to pass - I don't see any logs
indicating failures, and no kernel panics.
So the question is, does this patch break existing ublk servers? It does
break ublksrv as shown above, but I think one could argue that the above
code is just testing for file existence, and it's a bit weird to do that
by opening and closing the file (especially given that it's a device
special file). It can be patched to just use access or something
instead.
