[PATCH] make AS work nicely with SCSI

This allows SCSI to survive the I/O queueing stress harness with AS.

Jens has signed off on it, and Mark Havercamp confirms it also
eliminates the test induced hangs for him too.

diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index f6ca4f797e73abba0487792d976f4a628af780b3..a8fdb51dc0b4d2668297957a8e27c33b42924274 100644 (file)
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -1522,6 +1522,7 @@ void blk_requeue_request(request_queue_t *q, struct request *rq)
  * @rq:                request to be inserted
  * @at_head:   insert request at head or tail of queue
  * @data:      private data
+ * @reinsert:  true if request it a reinsertion of previously processed one
  *
  * Description:
  *    Many block devices need to execute commands asynchronously, so they don't
@@ -1536,7 +1537,7 @@ void blk_requeue_request(request_queue_t *q, struct request *rq)
  *    host that is unable to accept a particular command.
  */
 void blk_insert_request(request_queue_t *q, struct request *rq,
-                       int at_head, void *data)
+                       int at_head, void *data, int reinsert)
 {
        unsigned long flags;
 
@@ -1554,11 +1555,15 @@ void blk_insert_request(request_queue_t *q, struct request *rq,
        /*
         * If command is tagged, release the tag
         */
-       if (blk_rq_tagged(rq))
-               blk_queue_end_tag(q, rq);
+       if(reinsert) {
+               blk_requeue_request(q, rq);
+       } else {
+               if (blk_rq_tagged(rq))
+                       blk_queue_end_tag(q, rq);
 
-       drive_stat_acct(rq, rq->nr_sectors, 1);
-       __elv_add_request(q, rq, !at_head, 0);
+               drive_stat_acct(rq, rq->nr_sectors, 1);
+               __elv_add_request(q, rq, !at_head, 0);
+       }
        q->request_fn(q);
        spin_unlock_irqrestore(q->queue_lock, flags);
 }

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 3a5d82add006f78ce851a3047cbfe1788bb96660..63f62e89465c173cce4ffd7d2061341a01284925 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -69,7 +69,7 @@ int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
         */
        sreq->sr_request->flags &= ~REQ_DONTPREP;
        blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
-                          at_head, sreq);
+                          at_head, sreq, 0);
        return 0;
 }
 
@@ -147,7 +147,7 @@ int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
         * function.  The SCSI request function detects the blocked condition
         * and plugs the queue appropriately.
         */
-       blk_insert_request(device->request_queue, cmd->request, 1, cmd);
+       blk_insert_request(device->request_queue, cmd->request, 1, cmd, 1);
        return 0;
 }
 
@@ -445,7 +445,7 @@ static void scsi_run_queue(struct request_queue *q)
 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
 {
        cmd->request->flags &= ~REQ_DONTPREP;
-       blk_insert_request(q, cmd->request, 1, cmd);
+       blk_insert_request(q, cmd->request, 1, cmd, 1);
 
        scsi_run_queue(q);
 }

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index fa14b066b2bb91dcbc7dc899d8524f4bc870f3da..f31cbc86c39827946dbb95de59664eaf32a82761 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -491,7 +491,7 @@ extern void blk_attempt_remerge(request_queue_t *, struct request *);
 extern void __blk_attempt_remerge(request_queue_t *, struct request *);
 extern struct request *blk_get_request(request_queue_t *, int, int);
 extern void blk_put_request(struct request *);
-extern void blk_insert_request(request_queue_t *, struct request *, int, void *);
+extern void blk_insert_request(request_queue_t *, struct request *, int, void *, int);
 extern void blk_requeue_request(request_queue_t *, struct request *);
 extern void blk_plug_device(request_queue_t *);
 extern int blk_remove_plug(request_queue_t *);