Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

Make each fuse device clone refer to a separate processing queue.  The only
constraint on userspace code is that the request answer must be written to
the same device clone as it was read off.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

Allow fuse device clones to refer to be distinguished.  This patch just
adds the infrastructure by associating a separate "struct fuse_dev" with
each clone.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Allow an open fuse device to be "cloned".  Userspace can create a clone by:

      newfd = open("/dev/fuse", O_RDWR)
      ioctl(newfd, FUSE_DEV_IOC_CLONE, &oldfd);

At this point newfd will refer to the same fuse connection as oldfd.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

In fuse_abort_conn() when all requests are on private lists we no longer
need fc->lock protection.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Remove fc->lock protection from processing queue members, now protected by
fpq->lock.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

No longer need to call request_end() with the connection lock held.  We
still protect the background counters and queue with fc->lock, so acquire
it if necessary.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Now that we atomically test having already done everything we no longer
need other protection.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

When the connection is aborted it is possible that request_end() will be
called twice.  Use atomic test and set to do the actual ending only once.

test_and_set_bit() also provides the necessary barrier semantics so no
explicit smp_wmb() is necessary.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

When an unlocked request is aborted, it is moved from fpq->io to a private
list.  Then, after unlocking fpq->lock, the private list is processed and
the requests are finished off.

To protect the private list, we need to mark the request with a flag, so if
in the meantime the request is unlocked the list is not corrupted.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Add a fpq->lock for protecting members of struct fuse_pqueue and FR_LOCKED
request flag.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Rearrange fuse_abort_conn() so that processing queue accesses are grouped
together.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

 - locked list_add() + list_del_init() cancel out

 - common handling of case when request is ended here in the read phase
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

This will allow checking ->connected just with the processing queue lock.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

This is just two fields: fc->io and fc->processing.

This patch just rearranges the fields, no functional change.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

wait_event_interruptible_exclusive_locked() will do everything
request_wait() does, so replace it.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Remove fc->lock protection from input queue members, now protected by
fiq->waitq.lock.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Interrupt is only queued after the request has been sent to userspace.
This is either done in request_wait_answer() or fuse_dev_do_read()
depending on which state the request is in at the time of the interrupt.
If it's not yet sent, then queuing the interrupt is postponed until the
request is read.  Otherwise (the request has already been read and is
waiting for an answer) the interrupt is queued immedidately.

We want to call queue_interrupt() without fc->lock protection, in which
case there can be a race between the two functions:

 - neither of them queue the interrupt (thinking the other one has already
   done it).

 - both of them queue the interrupt

The first one is prevented by adding memory barriers, the second is
prevented by checking (under fiq->waitq.lock) if the interrupt has already
been queued.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

Use fiq->waitq.lock for protecting members of struct fuse_iqueue and
FR_PENDING request flag, previously protected by fc->lock.

Following patches will remove fc->lock protection from these members.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Different lists will need different locks.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Rearrange fuse_abort_conn() so that input queue accesses are grouped
together.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

This will allow checking ->connected just with the input queue lock.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

The input queue contains normal requests (fc->pending), forgets
(fc->forget_*) and interrupts (fc->interrupts).  There's also fc->waitq and
fc->fasync for waking up the readers of the fuse device when a request is
available.

The fc->reqctr is also moved to the input queue (assigned to the request
when the request is added to the input queue.

This patch just rearranges the fields, no functional change.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Use flags for representing the state in fuse_req.  This is needed since
req->list will be protected by different locks in different states, hence
we'll want the state itself to be split into distinct bits, each protected
with the relevant lock in that state.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

FUSE_REQ_INIT is actually the same state as FUSE_REQ_PENDING and
FUSE_REQ_READING and FUSE_REQ_WRITING can be merged into a common
FUSE_REQ_IO state.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Only hold fc->lock over sections of request_wait_answer() that actually
need it.  If wait_event_interruptible() returns zero, it means that the
request finished.  Need to add memory barriers, though, to make sure that
all relevant data in the request is synchronized.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

Since it's a 64bit counter, it's never gonna wrap around.  Remove code
dealing with that possibility.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Splice fc->pending and fc->processing lists into a common kill list while
holding fc->lock.

By the time we release fc->lock, pending and processing lists are empty and
the io list contains only locked requests.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Fold end_io_requests() and end_queued_requests() into fuse_abort_conn().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Reuse req->waitq.lock for protecting FR_ABORTED and FR_LOCKED flags.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Finer grained locking will mean there's no single lock to protect
modification of bitfileds in fuse_req.

So move to using bitops.  Can use the non-atomic variants for those which
happen while the request definitely has only one reference.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

 - don't end the request while req->locked is true

 - make unlock_request() return an error if the connection was aborted
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

fuse_abort_conn() does all the work done by fuse_dev_release() and more.
"More" consists of:

	end_io_requests(fc);
	wake_up_all(&fc->waitq);
	kill_fasync(&fc->fasync, SIGIO, POLL_IN);

All of which should be no-op (WARN_ON's added).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

And the same with fuse_request_send_nowait_locked().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

fc->conn_error is set once in FUSE_INIT reply and never cleared.  Check it
in request allocation, there's no sense in doing all the preparation if
sending will surely fail.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Move accounting of fc->num_waiting to the point where the request actually
starts waiting.  This is earlier than the current queue_request() for
background requests, since they might be waiting on the fc->bg_queue before
being queued on fc->pending.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

Reset req->waiting in fuse_put_request().  This is needed for correct
accounting in fc->num_waiting for reserved requests.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

request_end() expects fc->num_background and fc->active_background to have
been incremented, which is not the case in fuse_request_send_nowait()
failure path.  So instead just call the ->end() callback (which is actually
set by all callers).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

fc->release is called from fuse_conn_put() which was used in the error
cleanup before fc->release was initialized.

[Jeremiah Mahler <jmmahler@gmail.com>: assign fc->release after calling
fuse_conn_init(fc) instead of before.]
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Fixes: a325f9b9 ("fuse: update fuse_conn_init() and separate out fuse_conn_kill()")
Cc: <stable@vger.kernel.org> #v2.6.31+