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authorLars Ellenberg <lars.ellenberg@linbit.com>2013-11-22 15:52:03 +0400
committerPhilipp Reisner <philipp.reisner@linbit.com>2014-07-10 20:35:12 +0400
commit844a6ae7358df3261daec25e0d3a510f3d4152f2 (patch)
treeacdc6130cc3ed831dc1f5987494a241c73e0b9fa /drivers/block/drbd/drbd_req.c
parente5f891b2234dbab8c8797111a61519d0728ef855 (diff)
downloadlinux-844a6ae7358df3261daec25e0d3a510f3d4152f2.tar.xz
drbd: add lists to find oldest pending requests
Adding requests to per-device fifo lists as soon as possible after allocating them leaves a simple list_first_entry_or_null() to find the oldest request, regardless what it is still waiting for. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers/block/drbd/drbd_req.c')
-rw-r--r--drivers/block/drbd/drbd_req.c45
1 files changed, 33 insertions, 12 deletions
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 1319beab1b37..23cd909dc7f1 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -84,6 +84,8 @@ static struct drbd_request *drbd_req_new(struct drbd_device *device,
INIT_LIST_HEAD(&req->tl_requests);
INIT_LIST_HEAD(&req->w.list);
+ INIT_LIST_HEAD(&req->req_pending_master_completion);
+ INIT_LIST_HEAD(&req->req_pending_local);
/* one reference to be put by __drbd_make_request */
atomic_set(&req->completion_ref, 1);
@@ -120,12 +122,14 @@ void drbd_req_destroy(struct kref *kref)
return;
}
- /* remove it from the transfer log.
- * well, only if it had been there in the first
- * place... if it had not (local only or conflicting
- * and never sent), it should still be "empty" as
- * initialized in drbd_req_new(), so we can list_del() it
- * here unconditionally */
+ /* If called from mod_rq_state (expected normal case) or
+ * drbd_send_and_submit (the less likely normal path), this holds the
+ * req_lock, and req->tl_requests will typicaly be on ->transfer_log,
+ * though it may be still empty (never added to the transfer log).
+ *
+ * If called from do_retry(), we do NOT hold the req_lock, but we are
+ * still allowed to unconditionally list_del(&req->tl_requests),
+ * because it will be on a local on-stack list only. */
list_del_init(&req->tl_requests);
/* finally remove the request from the conflict detection
@@ -312,8 +316,15 @@ void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
if (req->i.waiting)
wake_up(&device->misc_wait);
+
+ /* Either we are about to complete to upper layers,
+ * or we will restart this request.
+ * In either case, the request object will be destroyed soon,
+ * so better remove it from all lists. */
+ list_del_init(&req->req_pending_master_completion);
}
+/* still holds resource->req_lock */
static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put)
{
struct drbd_device *device = req->device;
@@ -400,6 +411,7 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
++k_put;
else
++c_put;
+ list_del_init(&req->req_pending_local);
}
if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) {
@@ -1070,9 +1082,11 @@ drbd_submit_req_private_bio(struct drbd_request *req)
static void drbd_queue_write(struct drbd_device *device, struct drbd_request *req)
{
- spin_lock(&device->submit.lock);
+ spin_lock_irq(&device->resource->req_lock);
list_add_tail(&req->tl_requests, &device->submit.writes);
- spin_unlock(&device->submit.lock);
+ list_add_tail(&req->req_pending_master_completion,
+ &device->pending_master_completion[1 /* WRITE */]);
+ spin_unlock_irq(&device->resource->req_lock);
queue_work(device->submit.wq, &device->submit.worker);
}
@@ -1186,8 +1200,15 @@ static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request
no_remote = true;
}
+ /* If it took the fast path in drbd_request_prepare, add it here.
+ * The slow path has added it already. */
+ if (list_empty(&req->req_pending_master_completion))
+ list_add_tail(&req->req_pending_master_completion,
+ &device->pending_master_completion[rw == WRITE]);
if (req->private_bio) {
/* needs to be marked within the same spinlock */
+ list_add_tail(&req->req_pending_local,
+ &device->pending_completion[rw == WRITE]);
_req_mod(req, TO_BE_SUBMITTED);
/* but we need to give up the spinlock to submit */
submit_private_bio = true;
@@ -1278,9 +1299,9 @@ void do_submit(struct work_struct *ws)
struct drbd_request *req, *tmp;
for (;;) {
- spin_lock(&device->submit.lock);
+ spin_lock_irq(&device->resource->req_lock);
list_splice_tail_init(&device->submit.writes, &incoming);
- spin_unlock(&device->submit.lock);
+ spin_unlock_irq(&device->resource->req_lock);
submit_fast_path(device, &incoming);
if (list_empty(&incoming))
@@ -1304,9 +1325,9 @@ skip_fast_path:
if (list_empty(&device->submit.writes))
break;
- spin_lock(&device->submit.lock);
+ spin_lock_irq(&device->resource->req_lock);
list_splice_tail_init(&device->submit.writes, &more_incoming);
- spin_unlock(&device->submit.lock);
+ spin_unlock_irq(&device->resource->req_lock);
if (list_empty(&more_incoming))
break;