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| author | Tejun Heo <htejun@gmail.com> | 2005-04-24 02:04:21 -0500 |
|---|---|---|
| committer | James Bottomley <jejb@mulgrave.(none)> | 2005-05-20 12:53:26 -0500 |
| commit | 2e759cd4fa60c6df4cb117848274f444c2c0a12d (patch) | |
| tree | 973c2fd1725208de2d0a0ccd99b9fadd93a845fc /drivers | |
| parent | 354d6b2196c8e53e55e8f169804256ab9c72731d (diff) | |
| download | lwn-2e759cd4fa60c6df4cb117848274f444c2c0a12d.tar.gz lwn-2e759cd4fa60c6df4cb117848274f444c2c0a12d.zip | |
[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 <htejun@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/block/elevator.c | 13 |
1 files changed, 13 insertions, 0 deletions
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 @@ -291,6 +291,13 @@ void elv_requeue_request(request_queue_t *q, struct request *rq) } /* + * 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) { |