drbd: Removed the BIO_RW_BARRIER support form the receiver/epoch code

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

6 files changed, 33 insertions, 219 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 03c15e317c37..1b915fd9278f 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -749,17 +749,12 @@ struct drbd_epoch {
 
 /* drbd_epoch flag bits */
 enum {
-        DE_BARRIER_IN_NEXT_EPOCH_ISSUED,
-        DE_BARRIER_IN_NEXT_EPOCH_DONE,
-        DE_CONTAINS_A_BARRIER,
         DE_HAVE_BARRIER_NUMBER,
-        DE_IS_FINISHING,
 };
 
 enum epoch_event {
         EV_PUT,
         EV_GOT_BARRIER_NR,
-        EV_BARRIER_DONE,
         EV_BECAME_LAST,
         EV_CLEANUP = 32, /* used as flag */
 };
@@ -801,11 +796,6 @@ enum {
         __EE_CALL_AL_COMPLETE_IO,
         __EE_MAY_SET_IN_SYNC,
 
-        /* This epoch entry closes an epoch using a barrier.
-         * On sucessful completion, the epoch is released,
-         * and the P_BARRIER_ACK send. */
-        __EE_IS_BARRIER,
-
         /* In case a barrier failed,
          * we need to resubmit without the barrier flag. */
         __EE_RESUBMITTED,
@@ -820,7 +810,6 @@ enum {
 };
 #define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
 #define EE_MAY_SET_IN_SYNC     (1<<__EE_MAY_SET_IN_SYNC)
-#define EE_IS_BARRIER          (1<<__EE_IS_BARRIER)
 #define EE_RESUBMITTED         (1<<__EE_RESUBMITTED)
 #define EE_WAS_ERROR           (1<<__EE_WAS_ERROR)
 #define EE_HAS_DIGEST          (1<<__EE_HAS_DIGEST)
@@ -948,7 +937,6 @@ enum write_ordering_e {
         WO_none,
         WO_drain_io,
         WO_bdev_flush,
-        WO_bio_barrier
 };
 
 struct fifo_buffer {
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 992c3aecdf7e..8e0d707df23d 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2858,7 +2858,7 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
         drbd_thread_init(mdev, &mdev->asender, drbd_asender);
 
         mdev->agreed_pro_version = PRO_VERSION_MAX;
-        mdev->write_ordering = WO_bio_barrier;
+        mdev->write_ordering = WO_bdev_flush;
         mdev->resync_wenr = LC_FREE;
 }
 
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 0cba7d3d2b5d..899878fcf97d 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1117,8 +1117,8 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
         nbc = NULL;
         resync_lru = NULL;
 
-        mdev->write_ordering = WO_bio_barrier;
-        drbd_bump_write_ordering(mdev, WO_bio_barrier);
+        mdev->write_ordering = WO_bdev_flush;
+        drbd_bump_write_ordering(mdev, WO_bdev_flush);
 
         if (drbd_md_test_flag(mdev->ldev, MDF_CRASHED_PRIMARY))
                 set_bit(CRASHED_PRIMARY, &mdev->flags);
diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c
index ad325c5d0ce1..7e6ac307e2de 100644
--- a/drivers/block/drbd/drbd_proc.c
+++ b/drivers/block/drbd/drbd_proc.c
@@ -158,7 +158,6 @@ static int drbd_seq_show(struct seq_file *seq, void *v)
                 [WO_none] = 'n',
                 [WO_drain_io] = 'd',
                 [WO_bdev_flush] = 'f',
-                [WO_bio_barrier] = 'b',
         };
 
         seq_printf(seq, "version: " REL_VERSION " (api:%d/proto:%d-%d)\n%s\n",
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 1146faa7ae38..2952c1277b1d 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -49,11 +49,6 @@
 
 #include "drbd_vli.h"
 
-struct flush_work {
-        struct drbd_work w;
-        struct drbd_epoch *epoch;
-};
-
 enum finish_epoch {
         FE_STILL_LIVE,
         FE_DESTROYED,
@@ -66,16 +61,6 @@ static int drbd_do_auth(struct drbd_conf *mdev);
 static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *, struct drbd_epoch *, enum epoch_event);
 static int e_end_block(struct drbd_conf *, struct drbd_work *, int);
 
-static struct drbd_epoch *previous_epoch(struct drbd_conf *mdev, struct drbd_epoch *epoch)
-{
-        struct drbd_epoch *prev;
-        spin_lock(&mdev->epoch_lock);
-        prev = list_entry(epoch->list.prev, struct drbd_epoch, list);
-        if (prev == epoch || prev == mdev->current_epoch)
-                prev = NULL;
-        spin_unlock(&mdev->epoch_lock);
-        return prev;
-}
 
 #define GFP_TRY (__GFP_HIGHMEM | __GFP_NOWARN)
 
@@ -981,7 +966,7 @@ static int drbd_recv_header(struct drbd_conf *mdev, enum drbd_packets *cmd, unsi
         return TRUE;
 }
 
-static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct drbd_epoch *epoch)
+static void drbd_flush(struct drbd_conf *mdev)
 {
         int rv;
 
@@ -997,24 +982,6 @@ static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct d
                 }
                 put_ldev(mdev);
         }
-
-        return drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE);
-}
-
-static int w_flush(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
-{
-        struct flush_work *fw = (struct flush_work *)w;
-        struct drbd_epoch *epoch = fw->epoch;
-
-        kfree(w);
-
-        if (!test_and_set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags))
-                drbd_flush_after_epoch(mdev, epoch);
-
-        drbd_may_finish_epoch(mdev, epoch, EV_PUT |
-                              (mdev->state.conn < C_CONNECTED ? EV_CLEANUP : 0));
-
-        return 1;
 }
 
 /**
@@ -1027,15 +994,13 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
                                                struct drbd_epoch *epoch,
                                                enum epoch_event ev)
 {
-        int finish, epoch_size;
+        int epoch_size;
         struct drbd_epoch *next_epoch;
-        int schedule_flush = 0;
         enum finish_epoch rv = FE_STILL_LIVE;
 
         spin_lock(&mdev->epoch_lock);
         do {
                 next_epoch = NULL;
-                finish = 0;
 
                 epoch_size = atomic_read(&epoch->epoch_size);
 
@@ -1045,16 +1010,6 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
                         break;
                 case EV_GOT_BARRIER_NR:
                         set_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags);
-
-                        /* Special case: If we just switched from WO_bio_barrier to
-                           WO_bdev_flush we should not finish the current epoch */
-                        if (test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags) && epoch_size == 1 &&
-                            mdev->write_ordering != WO_bio_barrier &&
-                            epoch == mdev->current_epoch)
-                                clear_bit(DE_CONTAINS_A_BARRIER, &epoch->flags);
-                        break;
-                case EV_BARRIER_DONE:
-                        set_bit(DE_BARRIER_IN_NEXT_EPOCH_DONE, &epoch->flags);
                         break;
                 case EV_BECAME_LAST:
                         /* nothing to do*/
@@ -1063,23 +1018,7 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
 
                 if (epoch_size != 0 &&
                     atomic_read(&epoch->active) == 0 &&
-                    test_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags) &&
-                    epoch->list.prev == &mdev->current_epoch->list &&
-                    !test_bit(DE_IS_FINISHING, &epoch->flags)) {
-                        /* Nearly all conditions are met to finish that epoch... */
-                        if (test_bit(DE_BARRIER_IN_NEXT_EPOCH_DONE, &epoch->flags) ||
-                            mdev->write_ordering == WO_none ||
-                            (epoch_size == 1 && test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags)) ||
-                            ev & EV_CLEANUP) {
-                                finish = 1;
-                                set_bit(DE_IS_FINISHING, &epoch->flags);
-                        } else if (!test_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags) &&
-                                 mdev->write_ordering == WO_bio_barrier) {
-                                atomic_inc(&epoch->active);
-                                schedule_flush = 1;
-                        }
-                }
-                if (finish) {
+                    test_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags)) {
                         if (!(ev & EV_CLEANUP)) {
                                 spin_unlock(&mdev->epoch_lock);
                                 drbd_send_b_ack(mdev, epoch->barrier_nr, epoch_size);
@@ -1102,6 +1041,7 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
                                 /* atomic_set(&epoch->active, 0); is already zero */
                                 if (rv == FE_STILL_LIVE)
                                         rv = FE_RECYCLED;
+                                wake_up(&mdev->ee_wait);
                         }
                 }
 
@@ -1113,22 +1053,6 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
 
         spin_unlock(&mdev->epoch_lock);
 
-        if (schedule_flush) {
-                struct flush_work *fw;
-                fw = kmalloc(sizeof(*fw), GFP_ATOMIC);
-                if (fw) {
-                        fw->w.cb = w_flush;
-                        fw->epoch = epoch;
-                        drbd_queue_work(&mdev->data.work, &fw->w);
-                } else {
-                        dev_warn(DEV, "Could not kmalloc a flush_work obj\n");
-                        set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags);
-                        /* That is not a recursion, only one level */
-                        drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE);
-                        drbd_may_finish_epoch(mdev, epoch, EV_PUT);
-                }
-        }
-
         return rv;
 }
 
@@ -1144,19 +1068,16 @@ void drbd_bump_write_ordering(struct drbd_conf *mdev, enum write_ordering_e wo)
                 [WO_none] = "none",
                 [WO_drain_io] = "drain",
                 [WO_bdev_flush] = "flush",
-                [WO_bio_barrier] = "barrier",
         };
 
         pwo = mdev->write_ordering;
         wo = min(pwo, wo);
-        if (wo == WO_bio_barrier && mdev->ldev->dc.no_disk_barrier)
-                wo = WO_bdev_flush;
         if (wo == WO_bdev_flush && mdev->ldev->dc.no_disk_flush)
                 wo = WO_drain_io;
         if (wo == WO_drain_io && mdev->ldev->dc.no_disk_drain)
                 wo = WO_none;
         mdev->write_ordering = wo;
-        if (pwo != mdev->write_ordering || wo == WO_bio_barrier)
+        if (pwo != mdev->write_ordering || wo == WO_bdev_flush)
                 dev_info(DEV, "Method to ensure write ordering: %s\n", write_ordering_str[mdev->write_ordering]);
 }
 
@@ -1192,7 +1113,7 @@ next_bio:
         bio->bi_sector = sector;
         bio->bi_bdev = mdev->ldev->backing_bdev;
         /* we special case some flags in the multi-bio case, see below
-         * (REQ_UNPLUG, REQ_HARDBARRIER) */
+         * (REQ_UNPLUG) */
         bio->bi_rw = rw;
         bio->bi_private = e;
         bio->bi_end_io = drbd_endio_sec;
@@ -1226,11 +1147,6 @@ next_bio:
                         bio->bi_rw &= ~REQ_UNPLUG;
 
                 drbd_generic_make_request(mdev, fault_type, bio);
-
-                /* strip off REQ_HARDBARRIER,
-                 * unless it is the first or last bio */
-                if (bios && bios->bi_next)
-                        bios->bi_rw &= ~REQ_HARDBARRIER;
         } while (bios);
         maybe_kick_lo(mdev);
         return 0;
@@ -1244,45 +1160,9 @@ fail:
         return -ENOMEM;
 }
 
-/**
- * w_e_reissue() - Worker callback; Resubmit a bio, without REQ_HARDBARRIER set
- * @mdev:       DRBD device.
- * @w:          work object.
- * @cancel:     The connection will be closed anyways (unused in this callback)
- */
-int w_e_reissue(struct drbd_conf *mdev, struct drbd_work *w, int cancel) __releases(local)
-{
-        struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
-        /* We leave DE_CONTAINS_A_BARRIER and EE_IS_BARRIER in place,
-           (and DE_BARRIER_IN_NEXT_EPOCH_ISSUED in the previous Epoch)
-           so that we can finish that epoch in drbd_may_finish_epoch().
-           That is necessary if we already have a long chain of Epochs, before
-           we realize that REQ_HARDBARRIER is actually not supported */
-
-        /* As long as the -ENOTSUPP on the barrier is reported immediately
-           that will never trigger. If it is reported late, we will just
-           print that warning and continue correctly for all future requests
-           with WO_bdev_flush */
-        if (previous_epoch(mdev, e->epoch))
-                dev_warn(DEV, "Write ordering was not enforced (one time event)\n");
-
-        /* we still have a local reference,
-         * get_ldev was done in receive_Data. */
-
-        e->w.cb = e_end_block;
-        if (drbd_submit_ee(mdev, e, WRITE, DRBD_FAULT_DT_WR) != 0) {
-                /* drbd_submit_ee fails for one reason only:
-                 * if was not able to allocate sufficient bios.
-                 * requeue, try again later. */
-                e->w.cb = w_e_reissue;
-                drbd_queue_work(&mdev->data.work, &e->w);
-        }
-        return 1;
-}
-
 static int receive_Barrier(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned int data_size)
 {
-        int rv, issue_flush;
+        int rv;
         struct p_barrier *p = &mdev->data.rbuf.barrier;
         struct drbd_epoch *epoch;
 
@@ -1300,44 +1180,40 @@ static int receive_Barrier(struct drbd_conf *mdev, enum drbd_packets cmd, unsign
          * Therefore we must send the barrier_ack after the barrier request was
          * completed. */
         switch (mdev->write_ordering) {
-        case WO_bio_barrier:
         case WO_none:
                 if (rv == FE_RECYCLED)
                         return TRUE;
-                break;
+
+                /* receiver context, in the writeout path of the other node.
+                 * avoid potential distributed deadlock */
+                epoch = kmalloc(sizeof(struct drbd_epoch), GFP_NOIO);
+                if (epoch)
+                        break;
+                else
+                        dev_warn(DEV, "Allocation of an epoch failed, slowing down\n");
+                        /* Fall through */
 
         case WO_bdev_flush:
         case WO_drain_io:
-                if (rv == FE_STILL_LIVE) {
-                        set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &mdev->current_epoch->flags);
-                        drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
-                        rv = drbd_flush_after_epoch(mdev, mdev->current_epoch);
-                }
-                if (rv == FE_RECYCLED)
-                        return TRUE;
-
-                /* The asender will send all the ACKs and barrier ACKs out, since
-                   all EEs moved from the active_ee to the done_ee. We need to
-                   provide a new epoch object for the EEs that come in soon */
-                break;
-        }
-
-        /* receiver context, in the writeout path of the other node.
-         * avoid potential distributed deadlock */
-        epoch = kmalloc(sizeof(struct drbd_epoch), GFP_NOIO);
-        if (!epoch) {
-                dev_warn(DEV, "Allocation of an epoch failed, slowing down\n");
-                issue_flush = !test_and_set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &mdev->current_epoch->flags);
                 drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
-                if (issue_flush) {
-                        rv = drbd_flush_after_epoch(mdev, mdev->current_epoch);
-                        if (rv == FE_RECYCLED)
-                                return TRUE;
+                drbd_flush(mdev);
+
+                if (atomic_read(&mdev->current_epoch->epoch_size)) {
+                        epoch = kmalloc(sizeof(struct drbd_epoch), GFP_NOIO);
+                        if (epoch)
+                                break;
                 }
 
-                drbd_wait_ee_list_empty(mdev, &mdev->done_ee);
+                epoch = mdev->current_epoch;
+                wait_event(mdev->ee_wait, atomic_read(&epoch->epoch_size) == 0);
+
+                D_ASSERT(atomic_read(&epoch->active) == 0);
+                D_ASSERT(epoch->flags == 0);
 
                 return TRUE;
+        default:
+                dev_err(DEV, "Strangeness in mdev->write_ordering %d\n", mdev->write_ordering);
+                return FALSE;
         }
 
         epoch->flags = 0;
@@ -1652,15 +1528,8 @@ static int e_end_block(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 {
         struct drbd_epoch_entry *e = (struct drbd_epoch_entry *)w;
         sector_t sector = e->sector;
-        struct drbd_epoch *epoch;
         int ok = 1, pcmd;
 
-        if (e->flags & EE_IS_BARRIER) {
-                epoch = previous_epoch(mdev, e->epoch);
-                if (epoch)
-                        drbd_may_finish_epoch(mdev, epoch, EV_BARRIER_DONE + (cancel ? EV_CLEANUP : 0));
-        }
-
         if (mdev->net_conf->wire_protocol == DRBD_PROT_C) {
                 if (likely((e->flags & EE_WAS_ERROR) == 0)) {
                         pcmd = (mdev->state.conn >= C_SYNC_SOURCE &&
@@ -1817,27 +1686,6 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
         e->epoch = mdev->current_epoch;
         atomic_inc(&e->epoch->epoch_size);
         atomic_inc(&e->epoch->active);
-
-        if (mdev->write_ordering == WO_bio_barrier && atomic_read(&e->epoch->epoch_size) == 1) {
-                struct drbd_epoch *epoch;
-                /* Issue a barrier if we start a new epoch, and the previous epoch
-                   was not a epoch containing a single request which already was
-                   a Barrier. */
-                epoch = list_entry(e->epoch->list.prev, struct drbd_epoch, list);
-                if (epoch == e->epoch) {
-                        set_bit(DE_CONTAINS_A_BARRIER, &e->epoch->flags);
-                        rw |= REQ_HARDBARRIER;
-                        e->flags |= EE_IS_BARRIER;
-                } else {
-                        if (atomic_read(&epoch->epoch_size) > 1 ||
-                            !test_bit(DE_CONTAINS_A_BARRIER, &epoch->flags)) {
-                                set_bit(DE_BARRIER_IN_NEXT_EPOCH_ISSUED, &epoch->flags);
-                                set_bit(DE_CONTAINS_A_BARRIER, &e->epoch->flags);
-                                rw |= REQ_HARDBARRIER;
-                                e->flags |= EE_IS_BARRIER;
-                        }
-                }
-        }
         spin_unlock(&mdev->epoch_lock);
 
         dp_flags = be32_to_cpu(p->dp_flags);
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 1a2d2f0759b2..b0551ba7ad0c 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -102,12 +102,6 @@ void drbd_endio_read_sec_final(struct drbd_epoch_entry *e) __releases(local)
         put_ldev(mdev);
 }
 
-static int is_failed_barrier(int ee_flags)
-{
-        return (ee_flags & (EE_IS_BARRIER|EE_WAS_ERROR|EE_RESUBMITTED))
-                        == (EE_IS_BARRIER|EE_WAS_ERROR);
-}
-
 /* writes on behalf of the partner, or resync writes,
  * "submitted" by the receiver, final stage.  */
 static void drbd_endio_write_sec_final(struct drbd_epoch_entry *e) __releases(local)
@@ -119,21 +113,6 @@ static void drbd_endio_write_sec_final(struct drbd_epoch_entry *e) __releases(lo
         int is_syncer_req;
         int do_al_complete_io;
 
-        /* if this is a failed barrier request, disable use of barriers,
-         * and schedule for resubmission */
-        if (is_failed_barrier(e->flags)) {
-                drbd_bump_write_ordering(mdev, WO_bdev_flush);
-                spin_lock_irqsave(&mdev->req_lock, flags);
-                list_del(&e->w.list);
-                e->flags = (e->flags & ~EE_WAS_ERROR) | EE_RESUBMITTED;
-                e->w.cb = w_e_reissue;
-                /* put_ldev actually happens below, once we come here again. */
-                __release(local);
-                spin_unlock_irqrestore(&mdev->req_lock, flags);
-                drbd_queue_work(&mdev->data.work, &e->w);
-                return;
-        }
-
         D_ASSERT(e->block_id != ID_VACANT);
 
         /* after we moved e to done_ee,