don't access dlclose'd dynamic ioengine object after close

Alexey reported this bug when using dynamically loaded IO engines;
a segfault on the line where we set the dlhandle to NULL after
the dlclose.

I think this is because ops points to the thing we obtained from dlsym:

	ops = dlsym(dlhandle, engine_lib);

and after the final dlclose, the object no longer exists and efforts
to set the handle within it will fail for obvious reasons.
I'm not sure why I hadn't seen this before.

Reported-by: Alexey Dobriyan <>
Fixes: f6931a1 ("fio: move dynamic library handle to io_ops structure")
Tested-by: Alexey Dobriyan <>
Signed-off-by: Eric Sandeen <>
Signed-off-by: Jens Axboe <>
1 file changed