Messages in this thread |  | | | Date | Fri, 25 Mar 2011 16:22:28 +0100 | | From | Markus Trippelsdorf <> | | Subject | Re: [OOPS] elevator private data for REQ_FLUSH |
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On 2011.03.25 at 17:15 +0200, Sergey Senozhatsky wrote: > Hello, > > Commit > 9d5a4e946ce5352f19400b6370f4cd8e72806278 > block: skip elevator data initialization for flush requests > > Skip elevator initialization for flush requests by passing priv=0 to > blk_alloc_request() in get_request(). As such elv_set_request() is > never called for flush requests. > > introduced priv flag, to skip elevator_private data init for FLUSH requests. > This, I guess, lead to NULL pointer deref on my machine in cfq_insert_request, > which requires elevator_private to be set: > > 1 [ 78.982169] Call Trace: > 2 [ 78.982178] [<ffffffff8122d1fe>] cfq_insert_request+0x4e/0x47d > 3 [ 78.982184] [<ffffffff8123e139>] ? do_raw_spin_lock+0x6b/0x122
> Should we in that case use ELEVATOR_INSERT_FLUSH for REQ_FLUSH | REQ_FUA requests > (like below)? > > --- > > block/elevator.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/block/elevator.c b/block/elevator.c > index c387d31..b17e577 100644 > --- a/block/elevator.c > +++ b/block/elevator.c > @@ -734,6 +734,8 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where) > q->end_sector = rq_end_sector(rq); > q->boundary_rq = rq; > } > + } else if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) { > + where = ELEVATOR_INSERT_FLUSH; > } else if (!(rq->cmd_flags & REQ_ELVPRIV) && > where == ELEVATOR_INSERT_SORT) > where = ELEVATOR_INSERT_BACK;
Thanks. That solves all (corruption-) problems that I reported earlier in an other thread. -- Markus
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