block: unify request timeout handling

Right now SCSI and others do their own command timeout handling.
Move those bits to the block layer.

Instead of having a timer per command, we try to be a bit more clever
and simply have one per-queue. This avoids the overhead of having to
tear down and setup a timer for each command, so it will result in a lot
less timer fiddling.

Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/block/elevator.c b/block/elevator.c
index 8e3fc3afc77b..a91fc59edd01 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -36,6 +36,8 @@
 #include <linux/hash.h>
 #include <linux/uaccess.h>
 
+#include "blk.h"
+
 static DEFINE_SPINLOCK(elv_list_lock);
 static LIST_HEAD(elv_list);
 
@@ -771,6 +773,12 @@ struct request *elv_next_request(struct request_queue *q)
                          */
                         rq->cmd_flags |= REQ_STARTED;
                         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
+
+                        /*
+                         * We are now handing the request to the hardware,
+                         * add the timeout handler
+                         */
+                        blk_add_timer(rq);
                 }
 
                 if (!q->boundary_rq || q->boundary_rq == rq) {