From 844a6ae7358df3261daec25e0d3a510f3d4152f2 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Fri, 22 Nov 2013 12:52:03 +0100 Subject: [PATCH] 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 Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_int.h | 11 ++++++++- drivers/block/drbd/drbd_main.c | 7 +++++- drivers/block/drbd/drbd_req.c | 45 +++++++++++++++++++++++++--------- 3 files changed, 49 insertions(+), 14 deletions(-) diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h index 08fa2dc8cdba..f29f107be9b8 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -318,6 +318,10 @@ struct drbd_request { struct list_head tl_requests; /* ring list in the transfer log */ struct bio *master_bio; /* master bio pointer */ + /* see struct drbd_device */ + struct list_head req_pending_master_completion; + struct list_head req_pending_local; + /* for generic IO accounting */ unsigned long start_jif; @@ -738,7 +742,7 @@ struct submit_worker { struct workqueue_struct *wq; struct work_struct worker; - spinlock_t lock; + /* protected by ..->resource->req_lock */ struct list_head writes; }; @@ -795,6 +799,11 @@ struct drbd_device { struct rb_root read_requests; struct rb_root write_requests; + /* for statistics and timeouts */ + /* [0] read, [1] write */ + struct list_head pending_master_completion[2]; + struct list_head pending_completion[2]; + /* use checksums for *this* resync */ bool use_csums; /* blocks to resync in this run [unit BM_BLOCK_SIZE] */ diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index 0baec7a3fa81..58865969c9f4 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -1934,6 +1934,10 @@ void drbd_init_set_defaults(struct drbd_device *device) INIT_LIST_HEAD(&device->resync_work.list); INIT_LIST_HEAD(&device->unplug_work.list); INIT_LIST_HEAD(&device->bm_io_work.w.list); + INIT_LIST_HEAD(&device->pending_master_completion[0]); + INIT_LIST_HEAD(&device->pending_master_completion[1]); + INIT_LIST_HEAD(&device->pending_completion[0]); + INIT_LIST_HEAD(&device->pending_completion[1]); device->resync_work.cb = w_resync_timer; device->unplug_work.cb = w_send_write_hint; @@ -2268,6 +2272,8 @@ static void do_retry(struct work_struct *ws) } } +/* called via drbd_req_put_completion_ref(), + * holds resource->req_lock */ void drbd_restart_request(struct drbd_request *req) { unsigned long flags; @@ -2687,7 +2693,6 @@ static int init_submitter(struct drbd_device *device) return -ENOMEM; INIT_WORK(&device->submit.worker, do_submit); - spin_lock_init(&device->submit.lock); INIT_LIST_HEAD(&device->submit.writes); return 0; } 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; -- 2.20.1