block, cfq: fix empty queue crash caused by request merge
authorShaohua Li <shaohua.li@intel.com>
Fri, 16 Dec 2011 13:00:22 +0000 (14:00 +0100)
committerJens Axboe <axboe@kernel.dk>
Fri, 16 Dec 2011 13:00:22 +0000 (14:00 +0100)
commit4a0b75c7d02c2bd46ed227d4ba5941ba8a0aba5d
treea5a0c37a44c87227539ebc356178cc80435144d9
parentf1f8cc94651738b418ba54c039df536303b91704
block, cfq: fix empty queue crash caused by request merge

All requests of a queue could be merged to other requests of other queue.
Such queue will not have request in it, but it's in service tree. This
will cause kernel oops.
I encounter a BUG_ON() in cfq_dispatch_request() with next patch, but the
issue should exist without the patch.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block/cfq-iosched.c