Commit 595afaf9 authored Sep 07, 2010 by Miklos Szeredi

fuse: flush background queue on connection close



David Bartly reported that fuse can hang in fuse_get_req_nofail() when
the connection to the filesystem server is no longer active.

If bg_queue is not empty then flush_bg_queue() called from
request_end() can put more requests on to the pending queue.  If this
happens while ending requests on the processing queue then those
background requests will be queued to the pending list and never
ended.

Another problem is that fuse_dev_release() didn't wake up processes
sleeping on blocked_waitq.

Solve this by:

 a) flushing the background queue before calling end_requests() on the
    pending and processing queues

 b) setting blocked = 0 and waking up processes waiting on
    blocked_waitq()

Thanks to David for an excellent bug report.

Reported-by: David Bartley <andareed@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org

parent 2bfc96a1

fs/fuse/dev.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -1769,6 +1769,14 @@ __acquires(&fc->lock)
		}
		}

		static void end_queued_requests(struct fuse_conn *fc)
		{
		fc->max_background = UINT_MAX;
		flush_bg_queue(fc);
		end_requests(fc, &fc->pending);
		end_requests(fc, &fc->processing);
		}

		/*
		* Abort all requests.
		*
		@@ -1795,8 +1803,7 @@ void fuse_abort_conn(struct fuse_conn *fc)
		fc->connected = 0;
		fc->blocked = 0;
		end_io_requests(fc);
		end_requests(fc, &fc->pending);
		end_requests(fc, &fc->processing);
		end_queued_requests(fc);
		wake_up_all(&fc->waitq);
		wake_up_all(&fc->blocked_waitq);
		kill_fasync(&fc->fasync, SIGIO, POLL_IN);
		@@ -1811,8 +1818,9 @@ int fuse_dev_release(struct inode inode, struct file file)
		if (fc) {
		spin_lock(&fc->lock);
		fc->connected = 0;
		end_requests(fc, &fc->pending);
		end_requests(fc, &fc->processing);
		fc->blocked = 0;
		end_queued_requests(fc);
		wake_up_all(&fc->blocked_waitq);
		spin_unlock(&fc->lock);
		fuse_conn_put(fc);
		}

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