From 2e759cd4fa60c6df4cb117848274f444c2c0a12d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 24 Apr 2005 02:04:21 -0500 Subject: [SCSI] make blk layer set REQ_SOFTBARRIER on defer and requeue This is the reworked version of the patch. It sets REQ_SOFTBARRIER in two places - in elv_next_request() on BLKPREP_DEFER and in blk_requeue_request(). Signed-off-by: Tejun Heo Signed-off-by: James Bottomley --- drivers/block/elevator.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'drivers/block/elevator.c') diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c index 6b79b4314622..8c51d1ccebbd 100644 --- a/drivers/block/elevator.c +++ b/drivers/block/elevator.c @@ -290,6 +290,13 @@ void elv_requeue_request(request_queue_t *q, struct request *rq) rq = rq->end_io_data; } + /* + * the request is prepped and may have some resources allocated. + * allowing unprepped requests to pass this one may cause resource + * deadlock. turn on softbarrier. + */ + rq->flags |= REQ_SOFTBARRIER; + /* * if iosched has an explicit requeue hook, then use that. otherwise * just put the request at the front of the queue @@ -386,6 +393,12 @@ struct request *elv_next_request(request_queue_t *q) if (ret == BLKPREP_OK) { break; } else if (ret == BLKPREP_DEFER) { + /* + * the request may have been (partially) prepped. + * we need to keep this request in the front to + * avoid resource deadlock. turn on softbarrier. + */ + rq->flags |= REQ_SOFTBARRIER; rq = NULL; break; } else if (ret == BLKPREP_KILL) { -- cgit v1.2.2