Eh... I replied too early for this. I'm now trying to convert it to its
own handle but there is a rather serious problem. It's usually much
easier to have the entity to be waken up registered before calling
->poll so that ->poll can use the same notification path from ->poll ans
for later.
However, if we allocate poll handle from ->poll and tell it to kernel
via reply, it creates two problem. 1. the entity which is to be waken
up can't be registered prior to calling ->poll as there's nothing to
identify it, 2. the interval from reply write and in-kernel polled
entity registration must be made atomic so that no notification can come
through inbetween. #1 means that ->poll can't call the same
notification path from ->poll itself and #2 means that there needs to be
special provision from dev.c::fuse_dev_write() to
file.c::fuse_file_poll() so that atomicity can be guaranteed. Both of
which can be done but I'm not really sure whether using a separate
handle would be a good idea even with the involved cost.
Why do you think using separate poll handle would be better? And do you
still think the overhead is justifiable?
