[RFC] let LLD handle bsg_job_timeout

[Swen Schillig <swen.schillig@googlemail.com>]

The current fc_bsg_job_timeout function offers 
only two possibilities to a LLD to deal with timed out requests.
Either you deal with it offering a callback or not, 
in both scenarios the environment is cleaned up afterwards.

Unfortunately we (zfcp) don't have the option
to easily abort a request. Our hardware is running its 
own timer taking care of requests but unfortunately our only chance is
to wait until we receive a response. Up until then we need
the environment because the hardware might write into the provided
buffers.

The following code snippet would solve the issue for us
but maybe someone has a better idea on how to deal with the
described situation.

Cheers Swen
---
 drivers/scsi/scsi_transport_fc.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Index: HEAD/drivers/scsi/scsi_transport_fc.c
===================================================================
--- HEAD.orig/drivers/scsi/scsi_transport_fc.c
+++ HEAD/drivers/scsi/scsi_transport_fc.c
@@ -3500,7 +3500,10 @@ fc_bsg_job_timeout(struct request *req)
 	if (!done && i->f->bsg_timeout) {
 		/* call LLDD to abort the i/o as it has timed out */
 		err = i->f->bsg_timeout(job);
-		if (err)
+		if (err == -EAGAIN) {
+			job->ref_cnt--;
+			return BLK_EH_RESET_TIMER;
+		} else if (err)
 			printk(KERN_ERR "ERROR: FC BSG request timeout - LLD "
 				"abort failed with status %d\n", err);
 	}