5 files changed, 61 insertions, 23 deletions

diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index ba91b408abad..d84566496746 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -889,6 +889,7 @@ struct bm_aio_ctx {
         unsigned int done;
         unsigned flags;
 #define BM_AIO_COPY_PAGES       1
+#define BM_WRITE_ALL_PAGES      2
         int error;
         struct kref kref;
 };
@@ -1059,7 +1060,8 @@ static int bm_rw(struct drbd_conf *mdev, int rw, unsigned flags, unsigned lazy_w
                 if (lazy_writeout_upper_idx && i == lazy_writeout_upper_idx)
                         break;
                 if (rw & WRITE) {
-                        if (bm_test_page_unchanged(b->bm_pages[i])) {
+                        if (!(flags & BM_WRITE_ALL_PAGES) &&
+                            bm_test_page_unchanged(b->bm_pages[i])) {
                                 dynamic_dev_dbg(DEV, "skipped bm write for idx %u\n", i);
                                 continue;
                         }
@@ -1141,6 +1143,17 @@ int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local)
 }
 
 /**
+ * drbd_bm_write_all() - Write the whole bitmap to its on disk location.
+ * @mdev:       DRBD device.
+ *
+ * Will write all pages.
+ */
+int drbd_bm_write_all(struct drbd_conf *mdev) __must_hold(local)
+{
+        return bm_rw(mdev, WRITE, BM_WRITE_ALL_PAGES, 0);
+}
+
+/**
  * drbd_bm_lazy_write_out() - Write bitmap pages 0 to @upper_idx-1, if they have changed.
  * @mdev:       DRBD device.
  * @upper_idx:  0: write all changed pages; +ve: page index to stop scanning for changed pages
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index b2ca143d0053..b953cc7c9c00 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1469,6 +1469,7 @@ extern int  drbd_bm_e_weight(struct drbd_conf *mdev, unsigned long enr);
 extern int  drbd_bm_write_page(struct drbd_conf *mdev, unsigned int idx) __must_hold(local);
 extern int  drbd_bm_read(struct drbd_conf *mdev) __must_hold(local);
 extern int  drbd_bm_write(struct drbd_conf *mdev) __must_hold(local);
+extern int drbd_bm_write_all(struct drbd_conf *mdev) __must_hold(local);
 extern int  drbd_bm_write_copy_pages(struct drbd_conf *mdev) __must_hold(local);
 extern unsigned long drbd_bm_ALe_set_all(struct drbd_conf *mdev,
                 unsigned long al_enr);
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index dbe6135a2abe..f93a0320e952 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -79,6 +79,7 @@ static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused);
 static void md_sync_timer_fn(unsigned long data);
 static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused);
 static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+static void _tl_clear(struct drbd_conf *mdev);
 
 MODULE_AUTHOR("Philipp Reisner <phil@linbit.com>, "
               "Lars Ellenberg <lars@linbit.com>");
@@ -432,19 +433,10 @@ static void _tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
 
         /* Actions operating on the disk state, also want to work on
            requests that got barrier acked. */
-        switch (what) {
-        case fail_frozen_disk_io:
-        case restart_frozen_disk_io:
-                list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
-                        req = list_entry(le, struct drbd_request, tl_requests);
-                        _req_mod(req, what);
-                }
 
-        case connection_lost_while_pending:
-        case resend:
-                break;
-        default:
-                dev_err(DEV, "what = %d in _tl_restart()\n", what);
+        list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
+                req = list_entry(le, struct drbd_request, tl_requests);
+                _req_mod(req, what);
         }
 }
 
@@ -459,11 +451,16 @@ static void _tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
  */
 void tl_clear(struct drbd_conf *mdev)
 {
+        spin_lock_irq(&mdev->req_lock);
+        _tl_clear(mdev);
+        spin_unlock_irq(&mdev->req_lock);
+}
+
+static void _tl_clear(struct drbd_conf *mdev)
+{
         struct list_head *le, *tle;
         struct drbd_request *r;
 
-        spin_lock_irq(&mdev->req_lock);
-
         _tl_restart(mdev, connection_lost_while_pending);
 
         /* we expect this list to be empty. */
@@ -482,7 +479,6 @@ void tl_clear(struct drbd_conf *mdev)
 
         memset(mdev->app_reads_hash, 0, APP_R_HSIZE*sizeof(void *));
 
-        spin_unlock_irq(&mdev->req_lock);
 }
 
 void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
@@ -1476,12 +1472,12 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
         if (ns.susp_fen) {
                 /* case1: The outdate peer handler is successful: */
                 if (os.pdsk > D_OUTDATED  && ns.pdsk <= D_OUTDATED) {
-                        tl_clear(mdev);
                         if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
                                 drbd_uuid_new_current(mdev);
                                 clear_bit(NEW_CUR_UUID, &mdev->flags);
                         }
                         spin_lock_irq(&mdev->req_lock);
+                        _tl_clear(mdev);
                         _drbd_set_state(_NS(mdev, susp_fen, 0), CS_VERBOSE, NULL);
                         spin_unlock_irq(&mdev->req_lock);
                 }
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index fb9dce8daa24..edb490aad8b4 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -674,8 +674,8 @@ enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds
                          la_size_changed && md_moved ? "size changed and md moved" :
                          la_size_changed ? "size changed" : "md moved");
                 /* next line implicitly does drbd_suspend_io()+drbd_resume_io() */
-                err = drbd_bitmap_io(mdev, &drbd_bm_write,
-                                "size changed", BM_LOCKED_MASK);
+                err = drbd_bitmap_io(mdev, md_moved ? &drbd_bm_write_all : &drbd_bm_write,
+                                     "size changed", BM_LOCKED_MASK);
                 if (err) {
                         rv = dev_size_error;
                         goto out;
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 910335c30927..01b2ac641c7b 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -695,6 +695,12 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 break;
 
         case resend:
+                /* Simply complete (local only) READs. */
+                if (!(req->rq_state & RQ_WRITE) && !req->w.cb) {
+                        _req_may_be_done(req, m);
+                        break;
+                }
+
                 /* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK
                    before the connection loss (B&C only); only P_BARRIER_ACK was missing.
                    Trowing them out of the TL here by pretending we got a BARRIER_ACK
@@ -834,7 +840,15 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio, uns
                 req->private_bio = NULL;
         }
         if (rw == WRITE) {
-                remote = 1;
+                /* Need to replicate writes.  Unless it is an empty flush,
+                 * which is better mapped to a DRBD P_BARRIER packet,
+                 * also for drbd wire protocol compatibility reasons. */
+                if (unlikely(size == 0)) {
+                        /* The only size==0 bios we expect are empty flushes. */
+                        D_ASSERT(bio->bi_rw & REQ_FLUSH);
+                        remote = 0;
+                } else
+                        remote = 1;
         } else {
                 /* READ || READA */
                 if (local) {
@@ -870,8 +884,11 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio, uns
          * extent.  This waits for any resync activity in the corresponding
          * resync extent to finish, and, if necessary, pulls in the target
          * extent into the activity log, which involves further disk io because
-         * of transactional on-disk meta data updates. */
-        if (rw == WRITE && local && !test_bit(AL_SUSPENDED, &mdev->flags)) {
+         * of transactional on-disk meta data updates.
+         * Empty flushes don't need to go into the activity log, they can only
+         * flush data for pending writes which are already in there. */
+        if (rw == WRITE && local && size
+        && !test_bit(AL_SUSPENDED, &mdev->flags)) {
                 req->rq_state |= RQ_IN_ACT_LOG;
                 drbd_al_begin_io(mdev, sector);
         }
@@ -994,7 +1011,10 @@ allocate_barrier:
         if (rw == WRITE && _req_conflicts(req))
                 goto fail_conflicting;
 
-        list_add_tail(&req->tl_requests, &mdev->newest_tle->requests);
+        /* no point in adding empty flushes to the transfer log,
+         * they are mapped to drbd barriers already. */
+        if (likely(size!=0))
+                list_add_tail(&req->tl_requests, &mdev->newest_tle->requests);
 
         /* NOTE remote first: to get the concurrent write detection right,
          * we must register the request before start of local IO.  */
@@ -1014,6 +1034,14 @@ allocate_barrier:
             mdev->net_conf->on_congestion != OC_BLOCK && mdev->agreed_pro_version >= 96)
                 maybe_pull_ahead(mdev);
 
+        /* If this was a flush, queue a drbd barrier/start a new epoch.
+         * Unless the current epoch was empty anyways, or we are not currently
+         * replicating, in which case there is no point. */
+        if (unlikely(bio->bi_rw & REQ_FLUSH)
+                && mdev->newest_tle->n_writes
+                && drbd_should_do_remote(mdev->state))
+                queue_barrier(mdev);
+
         spin_unlock_irq(&mdev->req_lock);
         kfree(b); /* if someone else has beaten us to it... */