Merge branch 'for-jens' of git://git.drbd.org/linux-drbd into for-3.5/drivers

Philipp writes:

This are the updates we have in the drbd-8.3 tree. They are intended
for your "for-3.5/drivers" drivers branch.

These changes include one new feature:
 * Allow detach from frozen backing devices with the new --force option;
   configurable timeout for backing devices by the new disk-timeout option

And huge number of bug fixes:
 * Fixed a write ordering problem on SyncTarget nodes for a write
   to a block that gets resynced at the same time. The bug can
   only be triggered with a device that has a firmware that
   actually reorders writes to the same block
 * Fixed a race between disconnect and receive_state, that could cause
   a IO lockup
 * Fixed resend/resubmit for requests with disk or network timeout
 * Make sure that hard state changed do not disturb the connection
   establishing process (I.e. detach due to an IO error). When the
   bug was triggered it caused a retry in the connect process
 * Postpone soft state changes to no disturb the connection
   establishing process (I.e. becoming primary). When the bug
   was triggered it could cause both nodes going into SyncSource state
 * Fixed a refcount leak that could cause failures when trying to
   unload a protocol family modules, that was used by DRBD
 * Dedicated page pool for meta data IOs
 * Deny normal detach (as opposed to --forced) if the user tries
   to detach from the last UpToDate disk in the resource
 * Fixed a possible protocol error that could be caused by
   "unusual" BIOs.
 * Enforce the disk-timeout option also on meta-data IO operations
 * Implemented stable bitmap pages when we do a full write out of
   the bitmap
 * Fixed a rare compatibility issue with DRBD's older than 8.3.7
   when negotiating the bio_size
 * Fixed a rare race condition where an empty resync could stall with
   if pause/unpause events happen in parallel
 * Made the re-establishing of connections quicker, if it got a broken pipe
   once. Previously there was a bug in the code caused it to waste the first
   successful established connection after a broken pipe event.

PS: I am postponing the drbd-8.4 for mainline for one or two kernel
    development cycles more (the ~400 patchets set).

10 files changed, 741 insertions, 283 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index cf0e63dd97da..e54e31b02b88 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -65,39 +65,80 @@ struct drbd_atodb_wait {
 
 int w_al_write_transaction(struct drbd_conf *, struct drbd_work *, int);
 
+void *drbd_md_get_buffer(struct drbd_conf *mdev)
+{
+        int r;
+
+        wait_event(mdev->misc_wait,
+                   (r = atomic_cmpxchg(&mdev->md_io_in_use, 0, 1)) == 0 ||
+                   mdev->state.disk <= D_FAILED);
+
+        return r ? NULL : page_address(mdev->md_io_page);
+}
+
+void drbd_md_put_buffer(struct drbd_conf *mdev)
+{
+        if (atomic_dec_and_test(&mdev->md_io_in_use))
+                wake_up(&mdev->misc_wait);
+}
+
+static bool md_io_allowed(struct drbd_conf *mdev)
+{
+        enum drbd_disk_state ds = mdev->state.disk;
+        return ds >= D_NEGOTIATING || ds == D_ATTACHING;
+}
+
+void wait_until_done_or_disk_failure(struct drbd_conf *mdev, struct drbd_backing_dev *bdev,
+                                     unsigned int *done)
+{
+        long dt = bdev->dc.disk_timeout * HZ / 10;
+        if (dt == 0)
+                dt = MAX_SCHEDULE_TIMEOUT;
+
+        dt = wait_event_timeout(mdev->misc_wait, *done || !md_io_allowed(mdev), dt);
+        if (dt == 0)
+                dev_err(DEV, "meta-data IO operation timed out\n");
+}
+
 static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
                                  struct drbd_backing_dev *bdev,
                                  struct page *page, sector_t sector,
                                  int rw, int size)
 {
         struct bio *bio;
-        struct drbd_md_io md_io;
         int ok;
 
-        md_io.mdev = mdev;
-        init_completion(&md_io.event);
-        md_io.error = 0;
+        mdev->md_io.done = 0;
+        mdev->md_io.error = -ENODEV;
 
         if ((rw & WRITE) && !test_bit(MD_NO_FUA, &mdev->flags))
                 rw |= REQ_FUA | REQ_FLUSH;
         rw |= REQ_SYNC;
 
-        bio = bio_alloc(GFP_NOIO, 1);
+        bio = bio_alloc_drbd(GFP_NOIO);
         bio->bi_bdev = bdev->md_bdev;
         bio->bi_sector = sector;
         ok = (bio_add_page(bio, page, size, 0) == size);
         if (!ok)
                 goto out;
-        bio->bi_private = &md_io;
+        bio->bi_private = &mdev->md_io;
         bio->bi_end_io = drbd_md_io_complete;
         bio->bi_rw = rw;
 
+        if (!get_ldev_if_state(mdev, D_ATTACHING)) {  /* Corresponding put_ldev in drbd_md_io_complete() */
+                dev_err(DEV, "ASSERT FAILED: get_ldev_if_state() == 1 in _drbd_md_sync_page_io()\n");
+                ok = 0;
+                goto out;
+        }
+
+        bio_get(bio); /* one bio_put() is in the completion handler */
+        atomic_inc(&mdev->md_io_in_use); /* drbd_md_put_buffer() is in the completion handler */
         if (drbd_insert_fault(mdev, (rw & WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))
                 bio_endio(bio, -EIO);
         else
                 submit_bio(rw, bio);
-        wait_for_completion(&md_io.event);
-        ok = bio_flagged(bio, BIO_UPTODATE) && md_io.error == 0;
+        wait_until_done_or_disk_failure(mdev, bdev, &mdev->md_io.done);
+        ok = bio_flagged(bio, BIO_UPTODATE) && mdev->md_io.error == 0;
 
  out:
         bio_put(bio);
@@ -111,7 +152,7 @@ int drbd_md_sync_page_io(struct drbd_conf *mdev, struct drbd_backing_dev *bdev,
         int offset = 0;
         struct page *iop = mdev->md_io_page;
 
-        D_ASSERT(mutex_is_locked(&mdev->md_io_mutex));
+        D_ASSERT(atomic_read(&mdev->md_io_in_use) == 1);
 
         BUG_ON(!bdev->md_bdev);
 
@@ -328,8 +369,13 @@ w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
                 return 1;
         }
 
-        mutex_lock(&mdev->md_io_mutex); /* protects md_io_buffer, al_tr_cycle, ... */
-        buffer = (struct al_transaction *)page_address(mdev->md_io_page);
+        buffer = drbd_md_get_buffer(mdev); /* protects md_io_buffer, al_tr_cycle, ... */
+        if (!buffer) {
+                dev_err(DEV, "disk failed while waiting for md_io buffer\n");
+                complete(&((struct update_al_work *)w)->event);
+                put_ldev(mdev);
+                return 1;
+        }
 
         buffer->magic = __constant_cpu_to_be32(DRBD_MAGIC);
         buffer->tr_number = cpu_to_be32(mdev->al_tr_number);
@@ -374,7 +420,7 @@ w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
         D_ASSERT(mdev->al_tr_pos < MD_AL_MAX_SIZE);
         mdev->al_tr_number++;
 
-        mutex_unlock(&mdev->md_io_mutex);
+        drbd_md_put_buffer(mdev);
 
         complete(&((struct update_al_work *)w)->event);
         put_ldev(mdev);
@@ -443,8 +489,9 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
         /* lock out all other meta data io for now,
          * and make sure the page is mapped.
          */
-        mutex_lock(&mdev->md_io_mutex);
-        buffer = page_address(mdev->md_io_page);
+        buffer = drbd_md_get_buffer(mdev);
+        if (!buffer)
+                return 0;
 
         /* Find the valid transaction in the log */
         for (i = 0; i <= mx; i++) {
@@ -452,7 +499,7 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
                 if (rv == 0)
                         continue;
                 if (rv == -1) {
-                        mutex_unlock(&mdev->md_io_mutex);
+                        drbd_md_put_buffer(mdev);
                         return 0;
                 }
                 cnr = be32_to_cpu(buffer->tr_number);
@@ -478,7 +525,7 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 
         if (!found_valid) {
                 dev_warn(DEV, "No usable activity log found.\n");
-                mutex_unlock(&mdev->md_io_mutex);
+                drbd_md_put_buffer(mdev);
                 return 1;
         }
 
@@ -493,7 +540,7 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
                 rv = drbd_al_read_tr(mdev, bdev, buffer, i);
                 ERR_IF(rv == 0) goto cancel;
                 if (rv == -1) {
-                        mutex_unlock(&mdev->md_io_mutex);
+                        drbd_md_put_buffer(mdev);
                         return 0;
                 }
 
@@ -534,7 +581,7 @@ cancel:
                 mdev->al_tr_pos = 0;
 
         /* ok, we are done with it */
-        mutex_unlock(&mdev->md_io_mutex);
+        drbd_md_put_buffer(mdev);
 
         dev_info(DEV, "Found %d transactions (%d active extents) in activity log.\n",
              transactions, active_extents);
@@ -671,16 +718,20 @@ static void drbd_try_clear_on_disk_bm(struct drbd_conf *mdev, sector_t sector,
                         else
                                 ext->rs_failed += count;
                         if (ext->rs_left < ext->rs_failed) {
-                                dev_err(DEV, "BAD! sector=%llus enr=%u rs_left=%d "
-                                    "rs_failed=%d count=%d\n",
+                                dev_warn(DEV, "BAD! sector=%llus enr=%u rs_left=%d "
+                                    "rs_failed=%d count=%d cstate=%s\n",
                                      (unsigned long long)sector,
                                      ext->lce.lc_number, ext->rs_left,
-                                     ext->rs_failed, count);
-                                dump_stack();
-
-                                lc_put(mdev->resync, &ext->lce);
-                                drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
-                                return;
+                                     ext->rs_failed, count,
+                                     drbd_conn_str(mdev->state.conn));
+
+                                /* We don't expect to be able to clear more bits
+                                 * than have been set when we originally counted
+                                 * the set bits to cache that value in ext->rs_left.
+                                 * Whatever the reason (disconnect during resync,
+                                 * delayed local completion of an application write),
+                                 * try to fix it up by recounting here. */
+                                ext->rs_left = drbd_bm_e_weight(mdev, enr);
                         }
                 } else {
                         /* Normally this element should be in the cache,
@@ -1192,6 +1243,7 @@ int drbd_rs_del_all(struct drbd_conf *mdev)
                 put_ldev(mdev);
         }
         spin_unlock_irq(&mdev->al_lock);
+        wake_up(&mdev->al_wait);
 
         return 0;
 }
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index 3030201c69d8..b5c5ff53cb57 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -205,7 +205,7 @@ void drbd_bm_unlock(struct drbd_conf *mdev)
 static void bm_store_page_idx(struct page *page, unsigned long idx)
 {
         BUG_ON(0 != (idx & ~BM_PAGE_IDX_MASK));
-        page_private(page) |= idx;
+        set_page_private(page, idx);
 }
 
 static unsigned long bm_page_to_idx(struct page *page)
@@ -886,12 +886,21 @@ void drbd_bm_clear_all(struct drbd_conf *mdev)
 struct bm_aio_ctx {
         struct drbd_conf *mdev;
         atomic_t in_flight;
-        struct completion done;
+        unsigned int done;
         unsigned flags;
 #define BM_AIO_COPY_PAGES       1
         int error;
+        struct kref kref;
 };
 
+static void bm_aio_ctx_destroy(struct kref *kref)
+{
+        struct bm_aio_ctx *ctx = container_of(kref, struct bm_aio_ctx, kref);
+
+        put_ldev(ctx->mdev);
+        kfree(ctx);
+}
+
 /* bv_page may be a copy, or may be the original */
 static void bm_async_io_complete(struct bio *bio, int error)
 {
@@ -930,20 +939,21 @@ static void bm_async_io_complete(struct bio *bio, int error)
 
         bm_page_unlock_io(mdev, idx);
 
-        /* FIXME give back to page pool */
         if (ctx->flags & BM_AIO_COPY_PAGES)
-                put_page(bio->bi_io_vec[0].bv_page);
+                mempool_free(bio->bi_io_vec[0].bv_page, drbd_md_io_page_pool);
 
         bio_put(bio);
 
-        if (atomic_dec_and_test(&ctx->in_flight))
-                complete(&ctx->done);
+        if (atomic_dec_and_test(&ctx->in_flight)) {
+                ctx->done = 1;
+                wake_up(&mdev->misc_wait);
+                kref_put(&ctx->kref, &bm_aio_ctx_destroy);
+        }
 }
 
 static void bm_page_io_async(struct bm_aio_ctx *ctx, int page_nr, int rw) __must_hold(local)
 {
-        /* we are process context. we always get a bio */
-        struct bio *bio = bio_alloc(GFP_KERNEL, 1);
+        struct bio *bio = bio_alloc_drbd(GFP_NOIO);
         struct drbd_conf *mdev = ctx->mdev;
         struct drbd_bitmap *b = mdev->bitmap;
         struct page *page;
@@ -966,10 +976,8 @@ static void bm_page_io_async(struct bm_aio_ctx *ctx, int page_nr, int rw) __must
         bm_set_page_unchanged(b->bm_pages[page_nr]);
 
         if (ctx->flags & BM_AIO_COPY_PAGES) {
-                /* FIXME alloc_page is good enough for now, but actually needs
-                 * to use pre-allocated page pool */
                 void *src, *dest;
-                page = alloc_page(__GFP_HIGHMEM|__GFP_WAIT);
+                page = mempool_alloc(drbd_md_io_page_pool, __GFP_HIGHMEM|__GFP_WAIT);
                 dest = kmap_atomic(page);
                 src = kmap_atomic(b->bm_pages[page_nr]);
                 memcpy(dest, src, PAGE_SIZE);
@@ -981,6 +989,8 @@ static void bm_page_io_async(struct bm_aio_ctx *ctx, int page_nr, int rw) __must
 
         bio->bi_bdev = mdev->ldev->md_bdev;
         bio->bi_sector = on_disk_sector;
+        /* bio_add_page of a single page to an empty bio will always succeed,
+         * according to api.  Do we want to assert that? */
         bio_add_page(bio, page, len, 0);
         bio->bi_private = ctx;
         bio->bi_end_io = bm_async_io_complete;
@@ -999,14 +1009,9 @@ static void bm_page_io_async(struct bm_aio_ctx *ctx, int page_nr, int rw) __must
 /*
  * bm_rw: read/write the whole bitmap from/to its on disk location.
  */
-static int bm_rw(struct drbd_conf *mdev, int rw, unsigned lazy_writeout_upper_idx) __must_hold(local)
+static int bm_rw(struct drbd_conf *mdev, int rw, unsigned flags, unsigned lazy_writeout_upper_idx) __must_hold(local)
 {
-        struct bm_aio_ctx ctx = {
-                .mdev = mdev,
-                .in_flight = ATOMIC_INIT(1),
-                .done = COMPLETION_INITIALIZER_ONSTACK(ctx.done),
-                .flags = lazy_writeout_upper_idx ? BM_AIO_COPY_PAGES : 0,
-        };
+        struct bm_aio_ctx *ctx;
         struct drbd_bitmap *b = mdev->bitmap;
         int num_pages, i, count = 0;
         unsigned long now;
@@ -1021,7 +1026,27 @@ static int bm_rw(struct drbd_conf *mdev, int rw, unsigned lazy_writeout_upper_id
          * For lazy writeout, we don't care for ongoing changes to the bitmap,
          * as we submit copies of pages anyways.
          */
-        if (!ctx.flags)
+
+        ctx = kmalloc(sizeof(struct bm_aio_ctx), GFP_NOIO);
+        if (!ctx)
+                return -ENOMEM;
+
+        *ctx = (struct bm_aio_ctx) {
+                .mdev = mdev,
+                .in_flight = ATOMIC_INIT(1),
+                .done = 0,
+                .flags = flags,
+                .error = 0,
+                .kref = { ATOMIC_INIT(2) },
+        };
+
+        if (!get_ldev_if_state(mdev, D_ATTACHING)) {  /* put is in bm_aio_ctx_destroy() */
+                dev_err(DEV, "ASSERT FAILED: get_ldev_if_state() == 1 in bm_rw()\n");
+                kfree(ctx);
+                return -ENODEV;
+        }
+
+        if (!ctx->flags)
                 WARN_ON(!(BM_LOCKED_MASK & b->bm_flags));
 
         num_pages = b->bm_number_of_pages;
@@ -1046,29 +1071,38 @@ static int bm_rw(struct drbd_conf *mdev, int rw, unsigned lazy_writeout_upper_id
                                 continue;
                         }
                 }
-                atomic_inc(&ctx.in_flight);
-                bm_page_io_async(&ctx, i, rw);
+                atomic_inc(&ctx->in_flight);
+                bm_page_io_async(ctx, i, rw);
                 ++count;
                 cond_resched();
         }
 
         /*
-         * We initialize ctx.in_flight to one to make sure bm_async_io_complete
-         * will not complete() early, and decrement / test it here.  If there
+         * We initialize ctx->in_flight to one to make sure bm_async_io_complete
+         * will not set ctx->done early, and decrement / test it here.  If there
          * are still some bios in flight, we need to wait for them here.
+         * If all IO is done already (or nothing had been submitted), there is
+         * no need to wait.  Still, we need to put the kref associated with the
+         * "in_flight reached zero, all done" event.
          */
-        if (!atomic_dec_and_test(&ctx.in_flight))
-                wait_for_completion(&ctx.done);
+        if (!atomic_dec_and_test(&ctx->in_flight))
+                wait_until_done_or_disk_failure(mdev, mdev->ldev, &ctx->done);
+        else
+                kref_put(&ctx->kref, &bm_aio_ctx_destroy);
+
         dev_info(DEV, "bitmap %s of %u pages took %lu jiffies\n",
                         rw == WRITE ? "WRITE" : "READ",
                         count, jiffies - now);
 
-        if (ctx.error) {
+        if (ctx->error) {
                 dev_alert(DEV, "we had at least one MD IO ERROR during bitmap IO\n");
                 drbd_chk_io_error(mdev, 1, true);
-                err = -EIO; /* ctx.error ? */
+                err = -EIO; /* ctx->error ? */
         }
 
+        if (atomic_read(&ctx->in_flight))
+                err = -EIO; /* Disk failed during IO... */
+
         now = jiffies;
         if (rw == WRITE) {
                 drbd_md_flush(mdev);
@@ -1082,6 +1116,7 @@ static int bm_rw(struct drbd_conf *mdev, int rw, unsigned lazy_writeout_upper_id
         dev_info(DEV, "%s (%lu bits) marked out-of-sync by on disk bit-map.\n",
              ppsize(ppb, now << (BM_BLOCK_SHIFT-10)), now);
 
+        kref_put(&ctx->kref, &bm_aio_ctx_destroy);
         return err;
 }
 
@@ -1091,7 +1126,7 @@ static int bm_rw(struct drbd_conf *mdev, int rw, unsigned lazy_writeout_upper_id
  */
 int drbd_bm_read(struct drbd_conf *mdev) __must_hold(local)
 {
-        return bm_rw(mdev, READ, 0);
+        return bm_rw(mdev, READ, 0, 0);
 }
 
 /**
@@ -1102,7 +1137,7 @@ int drbd_bm_read(struct drbd_conf *mdev) __must_hold(local)
  */
 int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local)
 {
-        return bm_rw(mdev, WRITE, 0);
+        return bm_rw(mdev, WRITE, 0, 0);
 }
 
 /**
@@ -1112,7 +1147,23 @@ int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local)
  */
 int drbd_bm_write_lazy(struct drbd_conf *mdev, unsigned upper_idx) __must_hold(local)
 {
-        return bm_rw(mdev, WRITE, upper_idx);
+        return bm_rw(mdev, WRITE, BM_AIO_COPY_PAGES, upper_idx);
+}
+
+/**
+ * drbd_bm_write_copy_pages() - Write the whole bitmap to its on disk location.
+ * @mdev:       DRBD device.
+ *
+ * Will only write pages that have changed since last IO.
+ * In contrast to drbd_bm_write(), this will copy the bitmap pages
+ * to temporary writeout pages. It is intended to trigger a full write-out
+ * while still allowing the bitmap to change, for example if a resync or online
+ * verify is aborted due to a failed peer disk, while local IO continues, or
+ * pending resync acks are still being processed.
+ */
+int drbd_bm_write_copy_pages(struct drbd_conf *mdev) __must_hold(local)
+{
+        return bm_rw(mdev, WRITE, BM_AIO_COPY_PAGES, 0);
 }
 
 
@@ -1130,28 +1181,45 @@ int drbd_bm_write_lazy(struct drbd_conf *mdev, unsigned upper_idx) __must_hold(l
  */
 int drbd_bm_write_page(struct drbd_conf *mdev, unsigned int idx) __must_hold(local)
 {
-        struct bm_aio_ctx ctx = {
+        struct bm_aio_ctx *ctx;
+        int err;
+
+        if (bm_test_page_unchanged(mdev->bitmap->bm_pages[idx])) {
+                dynamic_dev_dbg(DEV, "skipped bm page write for idx %u\n", idx);
+                return 0;
+        }
+
+        ctx = kmalloc(sizeof(struct bm_aio_ctx), GFP_NOIO);
+        if (!ctx)
+                return -ENOMEM;
+
+        *ctx = (struct bm_aio_ctx) {
                 .mdev = mdev,
                 .in_flight = ATOMIC_INIT(1),
-                .done = COMPLETION_INITIALIZER_ONSTACK(ctx.done),
+                .done = 0,
                 .flags = BM_AIO_COPY_PAGES,
+                .error = 0,
+                .kref = { ATOMIC_INIT(2) },
         };
 
-        if (bm_test_page_unchanged(mdev->bitmap->bm_pages[idx])) {
-                dynamic_dev_dbg(DEV, "skipped bm page write for idx %u\n", idx);
-                return 0;
+        if (!get_ldev_if_state(mdev, D_ATTACHING)) {  /* put is in bm_aio_ctx_destroy() */
+                dev_err(DEV, "ASSERT FAILED: get_ldev_if_state() == 1 in drbd_bm_write_page()\n");
+                kfree(ctx);
+                return -ENODEV;
         }
 
-        bm_page_io_async(&ctx, idx, WRITE_SYNC);
-        wait_for_completion(&ctx.done);
+        bm_page_io_async(ctx, idx, WRITE_SYNC);
+        wait_until_done_or_disk_failure(mdev, mdev->ldev, &ctx->done);
 
-        if (ctx.error)
+        if (ctx->error)
                 drbd_chk_io_error(mdev, 1, true);
                 /* that should force detach, so the in memory bitmap will be
                  * gone in a moment as well. */
 
         mdev->bm_writ_cnt++;
-        return ctx.error;
+        err = atomic_read(&ctx->in_flight) ? -EIO : ctx->error;
+        kref_put(&ctx->kref, &bm_aio_ctx_destroy);
+        return err;
 }
 
 /* NOTE
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 8d680562ba73..02f013a073a7 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -712,7 +712,6 @@ struct drbd_request {
         struct list_head tl_requests; /* ring list in the transfer log */
         struct bio *master_bio;       /* master bio pointer */
         unsigned long rq_state; /* see comments above _req_mod() */
-        int seq_num;
         unsigned long start_time;
 };
 
@@ -851,6 +850,7 @@ enum {
         NEW_CUR_UUID,           /* Create new current UUID when thawing IO */
         AL_SUSPENDED,           /* Activity logging is currently suspended. */
         AHEAD_TO_SYNC_SOURCE,   /* Ahead -> SyncSource queued */
+        STATE_SENT,             /* Do not change state/UUIDs while this is set */
 };
 
 struct drbd_bitmap; /* opaque for drbd_conf */
@@ -862,31 +862,30 @@ enum bm_flag {
         BM_P_VMALLOCED = 0x10000, /* internal use only, will be masked out */
 
         /* currently locked for bulk operation */
-        BM_LOCKED_MASK = 0x7,
+        BM_LOCKED_MASK = 0xf,
 
         /* in detail, that is: */
         BM_DONT_CLEAR = 0x1,
         BM_DONT_SET   = 0x2,
         BM_DONT_TEST  = 0x4,
 
+        /* so we can mark it locked for bulk operation,
+         * and still allow all non-bulk operations */
+        BM_IS_LOCKED  = 0x8,
+
         /* (test bit, count bit) allowed (common case) */
-        BM_LOCKED_TEST_ALLOWED = 0x3,
+        BM_LOCKED_TEST_ALLOWED = BM_DONT_CLEAR | BM_DONT_SET | BM_IS_LOCKED,
 
         /* testing bits, as well as setting new bits allowed, but clearing bits
          * would be unexpected.  Used during bitmap receive.  Setting new bits
          * requires sending of "out-of-sync" information, though. */
-        BM_LOCKED_SET_ALLOWED = 0x1,
+        BM_LOCKED_SET_ALLOWED = BM_DONT_CLEAR | BM_IS_LOCKED,
 
-        /* clear is not expected while bitmap is locked for bulk operation */
+        /* for drbd_bm_write_copy_pages, everything is allowed,
+         * only concurrent bulk operations are locked out. */
+        BM_LOCKED_CHANGE_ALLOWED = BM_IS_LOCKED,
 };
 
-
-/* TODO sort members for performance
- * MAYBE group them further */
-
-/* THINK maybe we actually want to use the default "event/%s" worker threads
- * or similar in linux 2.6, which uses per cpu data and threads.
- */
 struct drbd_work_queue {
         struct list_head q;
         struct semaphore s; /* producers up it, worker down()s it */
@@ -938,8 +937,7 @@ struct drbd_backing_dev {
 };
 
 struct drbd_md_io {
-        struct drbd_conf *mdev;
-        struct completion event;
+        unsigned int done;
         int error;
 };
 
@@ -1022,6 +1020,7 @@ struct drbd_conf {
         struct drbd_tl_epoch *newest_tle;
         struct drbd_tl_epoch *oldest_tle;
         struct list_head out_of_sequence_requests;
+        struct list_head barrier_acked_requests;
         struct hlist_head *tl_hash;
         unsigned int tl_hash_s;
 
@@ -1056,6 +1055,8 @@ struct drbd_conf {
         struct crypto_hash *csums_tfm;
         struct crypto_hash *verify_tfm;
 
+        unsigned long last_reattach_jif;
+        unsigned long last_reconnect_jif;
         struct drbd_thread receiver;
         struct drbd_thread worker;
         struct drbd_thread asender;
@@ -1094,7 +1095,8 @@ struct drbd_conf {
         wait_queue_head_t ee_wait;
         struct page *md_io_page;        /* one page buffer for md_io */
         struct page *md_io_tmpp;        /* for logical_block_size != 512 */
-        struct mutex md_io_mutex;       /* protects the md_io_buffer */
+        struct drbd_md_io md_io;
+        atomic_t md_io_in_use;          /* protects the md_io, md_io_page and md_io_tmpp */
         spinlock_t al_lock;
         wait_queue_head_t al_wait;
         struct lru_cache *act_log;      /* activity log */
@@ -1228,8 +1230,8 @@ extern int drbd_send_uuids(struct drbd_conf *mdev);
 extern int drbd_send_uuids_skip_initial_sync(struct drbd_conf *mdev);
 extern int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev);
 extern int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags flags);
-extern int _drbd_send_state(struct drbd_conf *mdev);
-extern int drbd_send_state(struct drbd_conf *mdev);
+extern int drbd_send_state(struct drbd_conf *mdev, union drbd_state s);
+extern int drbd_send_current_state(struct drbd_conf *mdev);
 extern int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,
                         enum drbd_packets cmd, struct p_header80 *h,
                         size_t size, unsigned msg_flags);
@@ -1461,6 +1463,7 @@ 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_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);
 extern size_t        drbd_bm_words(struct drbd_conf *mdev);
@@ -1493,11 +1496,38 @@ extern struct kmem_cache *drbd_al_ext_cache;	/* activity log extents */
 extern mempool_t *drbd_request_mempool;
 extern mempool_t *drbd_ee_mempool;
 
-extern struct page *drbd_pp_pool; /* drbd's page pool */
+/* drbd's page pool, used to buffer data received from the peer,
+ * or data requested by the peer.
+ *
+ * This does not have an emergency reserve.
+ *
+ * When allocating from this pool, it first takes pages from the pool.
+ * Only if the pool is depleted will try to allocate from the system.
+ *
+ * The assumption is that pages taken from this pool will be processed,
+ * and given back, "quickly", and then can be recycled, so we can avoid
+ * frequent calls to alloc_page(), and still will be able to make progress even
+ * under memory pressure.
+ */
+extern struct page *drbd_pp_pool;
 extern spinlock_t   drbd_pp_lock;
 extern int          drbd_pp_vacant;
 extern wait_queue_head_t drbd_pp_wait;
 
+/* We also need a standard (emergency-reserve backed) page pool
+ * for meta data IO (activity log, bitmap).
+ * We can keep it global, as long as it is used as "N pages at a time".
+ * 128 should be plenty, currently we probably can get away with as few as 1.
+ */
+#define DRBD_MIN_POOL_PAGES     128
+extern mempool_t *drbd_md_io_page_pool;
+
+/* We also need to make sure we get a bio
+ * when we need it for housekeeping purposes */
+extern struct bio_set *drbd_md_io_bio_set;
+/* to allocate from that set */
+extern struct bio *bio_alloc_drbd(gfp_t gfp_mask);
+
 extern rwlock_t global_state_lock;
 
 extern struct drbd_conf *drbd_new_device(unsigned int minor);
@@ -1536,8 +1566,12 @@ extern void resume_next_sg(struct drbd_conf *mdev);
 extern void suspend_other_sg(struct drbd_conf *mdev);
 extern int drbd_resync_finished(struct drbd_conf *mdev);
 /* maybe rather drbd_main.c ? */
+extern void *drbd_md_get_buffer(struct drbd_conf *mdev);
+extern void drbd_md_put_buffer(struct drbd_conf *mdev);
 extern int drbd_md_sync_page_io(struct drbd_conf *mdev,
-                struct drbd_backing_dev *bdev, sector_t sector, int rw);
+                                struct drbd_backing_dev *bdev, sector_t sector, int rw);
+extern void wait_until_done_or_disk_failure(struct drbd_conf *mdev, struct drbd_backing_dev *bdev,
+                                            unsigned int *done);
 extern void drbd_ov_oos_found(struct drbd_conf*, sector_t, int);
 extern void drbd_rs_controller_reset(struct drbd_conf *mdev);
 
@@ -1754,19 +1788,6 @@ static inline struct page *page_chain_next(struct page *page)
 #define page_chain_for_each_safe(page, n) \
         for (; page && ({ n = page_chain_next(page); 1; }); page = n)
 
-static inline int drbd_bio_has_active_page(struct bio *bio)
-{
-        struct bio_vec *bvec;
-        int i;
-
-        __bio_for_each_segment(bvec, bio, i, 0) {
-                if (page_count(bvec->bv_page) > 1)
-                        return 1;
-        }
-
-        return 0;
-}
-
 static inline int drbd_ee_has_active_page(struct drbd_epoch_entry *e)
 {
         struct page *page = e->pages;
@@ -1777,7 +1798,6 @@ static inline int drbd_ee_has_active_page(struct drbd_epoch_entry *e)
         return 0;
 }
 
-
 static inline void drbd_state_lock(struct drbd_conf *mdev)
 {
         wait_event(mdev->misc_wait,
@@ -2230,7 +2250,7 @@ static inline void drbd_get_syncer_progress(struct drbd_conf *mdev,
                  * Note: currently we don't support such large bitmaps on 32bit
                  * arch anyways, but no harm done to be prepared for it here.
                  */
-                unsigned int shift = mdev->rs_total >= (1ULL << 32) ? 16 : 10;
+                unsigned int shift = mdev->rs_total > UINT_MAX ? 16 : 10;
                 unsigned long left = *bits_left >> shift;
                 unsigned long total = 1UL + (mdev->rs_total >> shift);
                 unsigned long tmp = 1000UL - left * 1000UL/total;
@@ -2306,12 +2326,12 @@ static inline int drbd_state_is_stable(struct drbd_conf *mdev)
         case D_OUTDATED:
         case D_CONSISTENT:
         case D_UP_TO_DATE:
+        case D_FAILED:
                 /* disk state is stable as well. */
                 break;
 
         /* no new io accepted during tansitional states */
         case D_ATTACHING:
-        case D_FAILED:
         case D_NEGOTIATING:
         case D_UNKNOWN:
         case D_MASK:
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 211fc44f84be..920ede2829d6 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -139,6 +139,8 @@ struct kmem_cache *drbd_bm_ext_cache;	/* bitmap extents */
 struct kmem_cache *drbd_al_ext_cache;   /* activity log extents */
 mempool_t *drbd_request_mempool;
 mempool_t *drbd_ee_mempool;
+mempool_t *drbd_md_io_page_pool;
+struct bio_set *drbd_md_io_bio_set;
 
 /* I do not use a standard mempool, because:
    1) I want to hand out the pre-allocated objects first.
@@ -159,7 +161,24 @@ static const struct block_device_operations drbd_ops = {
         .release = drbd_release,
 };
 
-#define ARRY_SIZE(A) (sizeof(A)/sizeof(A[0]))
+static void bio_destructor_drbd(struct bio *bio)
+{
+        bio_free(bio, drbd_md_io_bio_set);
+}
+
+struct bio *bio_alloc_drbd(gfp_t gfp_mask)
+{
+        struct bio *bio;
+
+        if (!drbd_md_io_bio_set)
+                return bio_alloc(gfp_mask, 1);
+
+        bio = bio_alloc_bioset(gfp_mask, 1, drbd_md_io_bio_set);
+        if (!bio)
+                return NULL;
+        bio->bi_destructor = bio_destructor_drbd;
+        return bio;
+}
 
 #ifdef __CHECKER__
 /* When checking with sparse, and this is an inline function, sparse will
@@ -208,6 +227,7 @@ static int tl_init(struct drbd_conf *mdev)
         mdev->oldest_tle = b;
         mdev->newest_tle = b;
         INIT_LIST_HEAD(&mdev->out_of_sequence_requests);
+        INIT_LIST_HEAD(&mdev->barrier_acked_requests);
 
         mdev->tl_hash = NULL;
         mdev->tl_hash_s = 0;
@@ -246,9 +266,7 @@ void _tl_add_barrier(struct drbd_conf *mdev, struct drbd_tl_epoch *new)
         new->n_writes = 0;
 
         newest_before = mdev->newest_tle;
-        /* never send a barrier number == 0, because that is special-cased
-         * when using TCQ for our write ordering code */
-        new->br_number = (newest_before->br_number+1) ?: 1;
+        new->br_number = newest_before->br_number+1;
         if (mdev->newest_tle != new) {
                 mdev->newest_tle->next = new;
                 mdev->newest_tle = new;
@@ -311,7 +329,7 @@ void tl_release(struct drbd_conf *mdev, unsigned int barrier_nr,
            These have been list_move'd to the out_of_sequence_requests list in
            _req_mod(, barrier_acked) above.
            */
-        list_del_init(&b->requests);
+        list_splice_init(&b->requests, &mdev->barrier_acked_requests);
 
         nob = b->next;
         if (test_and_clear_bit(CREATE_BARRIER, &mdev->flags)) {
@@ -411,6 +429,23 @@ static void _tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
                 b = tmp;
                 list_splice(&carry_reads, &b->requests);
         }
+
+        /* 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);
+        }
 }
 
 
@@ -458,6 +493,38 @@ void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
 }
 
 /**
+ * tl_abort_disk_io() - Abort disk I/O for all requests for a certain mdev in the TL
+ * @mdev:       DRBD device.
+ */
+void tl_abort_disk_io(struct drbd_conf *mdev)
+{
+        struct drbd_tl_epoch *b;
+        struct list_head *le, *tle;
+        struct drbd_request *req;
+
+        spin_lock_irq(&mdev->req_lock);
+        b = mdev->oldest_tle;
+        while (b) {
+                list_for_each_safe(le, tle, &b->requests) {
+                        req = list_entry(le, struct drbd_request, tl_requests);
+                        if (!(req->rq_state & RQ_LOCAL_PENDING))
+                                continue;
+                        _req_mod(req, abort_disk_io);
+                }
+                b = b->next;
+        }
+
+        list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
+                req = list_entry(le, struct drbd_request, tl_requests);
+                if (!(req->rq_state & RQ_LOCAL_PENDING))
+                        continue;
+                _req_mod(req, abort_disk_io);
+        }
+
+        spin_unlock_irq(&mdev->req_lock);
+}
+
+/**
  * cl_wide_st_chg() - true if the state change is a cluster wide one
  * @mdev:       DRBD device.
  * @os:         old (current) state.
@@ -470,7 +537,7 @@ static int cl_wide_st_chg(struct drbd_conf *mdev,
                  ((os.role != R_PRIMARY && ns.role == R_PRIMARY) ||
                   (os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
                   (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S) ||
-                  (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))) ||
+                  (os.disk != D_FAILED && ns.disk == D_FAILED))) ||
                 (os.conn >= C_CONNECTED && ns.conn == C_DISCONNECTING) ||
                 (os.conn == C_CONNECTED && ns.conn == C_VERIFY_S);
 }
@@ -509,8 +576,16 @@ static enum drbd_state_rv is_valid_state(struct drbd_conf *, union drbd_state);
 static enum drbd_state_rv is_valid_state_transition(struct drbd_conf *,
                                                     union drbd_state,
                                                     union drbd_state);
+enum sanitize_state_warnings {
+        NO_WARNING,
+        ABORTED_ONLINE_VERIFY,
+        ABORTED_RESYNC,
+        CONNECTION_LOST_NEGOTIATING,
+        IMPLICITLY_UPGRADED_DISK,
+        IMPLICITLY_UPGRADED_PDSK,
+};
 static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
-                                       union drbd_state ns, const char **warn_sync_abort);
+                                       union drbd_state ns, enum sanitize_state_warnings *warn);
 int drbd_send_state_req(struct drbd_conf *,
                         union drbd_state, union drbd_state);
 
@@ -785,6 +860,13 @@ is_valid_state_transition(struct drbd_conf *mdev, union drbd_state ns,
         if (ns.conn == os.conn && ns.conn == C_WF_REPORT_PARAMS)
                 rv = SS_IN_TRANSIENT_STATE;
 
+        /* While establishing a connection only allow cstate to change.
+           Delay/refuse role changes, detach attach etc... */
+        if (test_bit(STATE_SENT, &mdev->flags) &&
+            !(os.conn == C_WF_REPORT_PARAMS ||
+              (ns.conn == C_WF_REPORT_PARAMS && os.conn == C_WF_CONNECTION)))
+                rv = SS_IN_TRANSIENT_STATE;
+
         if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) && os.conn < C_CONNECTED)
                 rv = SS_NEED_CONNECTION;
 
@@ -803,6 +885,21 @@ is_valid_state_transition(struct drbd_conf *mdev, union drbd_state ns,
         return rv;
 }
 
+static void print_sanitize_warnings(struct drbd_conf *mdev, enum sanitize_state_warnings warn)
+{
+        static const char *msg_table[] = {
+                [NO_WARNING] = "",
+                [ABORTED_ONLINE_VERIFY] = "Online-verify aborted.",
+                [ABORTED_RESYNC] = "Resync aborted.",
+                [CONNECTION_LOST_NEGOTIATING] = "Connection lost while negotiating, no data!",
+                [IMPLICITLY_UPGRADED_DISK] = "Implicitly upgraded disk",
+                [IMPLICITLY_UPGRADED_PDSK] = "Implicitly upgraded pdsk",
+        };
+
+        if (warn != NO_WARNING)
+                dev_warn(DEV, "%s\n", msg_table[warn]);
+}
+
 /**
  * sanitize_state() - Resolves implicitly necessary additional changes to a state transition
  * @mdev:       DRBD device.
@@ -814,11 +911,14 @@ is_valid_state_transition(struct drbd_conf *mdev, union drbd_state ns,
  * to D_UNKNOWN. This rule and many more along those lines are in this function.
  */
 static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
-                                       union drbd_state ns, const char **warn_sync_abort)
+                                       union drbd_state ns, enum sanitize_state_warnings *warn)
 {
         enum drbd_fencing_p fp;
         enum drbd_disk_state disk_min, disk_max, pdsk_min, pdsk_max;
 
+        if (warn)
+                *warn = NO_WARNING;
+
         fp = FP_DONT_CARE;
         if (get_ldev(mdev)) {
                 fp = mdev->ldev->dc.fencing;
@@ -833,18 +933,13 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
         /* After a network error (+C_TEAR_DOWN) only C_UNCONNECTED or C_DISCONNECTING can follow.
          * If you try to go into some Sync* state, that shall fail (elsewhere). */
         if (os.conn >= C_TIMEOUT && os.conn <= C_TEAR_DOWN &&
-            ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING && ns.conn <= C_TEAR_DOWN)
+            ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING && ns.conn <= C_CONNECTED)
                 ns.conn = os.conn;
 
         /* we cannot fail (again) if we already detached */
         if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
                 ns.disk = D_DISKLESS;
 
-        /* if we are only D_ATTACHING yet,
-         * we can (and should) go directly to D_DISKLESS. */
-        if (ns.disk == D_FAILED && os.disk == D_ATTACHING)
-                ns.disk = D_DISKLESS;
-
         /* After C_DISCONNECTING only C_STANDALONE may follow */
         if (os.conn == C_DISCONNECTING && ns.conn != C_STANDALONE)
                 ns.conn = os.conn;
@@ -863,10 +958,9 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
         /* Abort resync if a disk fails/detaches */
         if (os.conn > C_CONNECTED && ns.conn > C_CONNECTED &&
             (ns.disk <= D_FAILED || ns.pdsk <= D_FAILED)) {
-                if (warn_sync_abort)
-                        *warn_sync_abort =
-                                os.conn == C_VERIFY_S || os.conn == C_VERIFY_T ?
-                                "Online-verify" : "Resync";
+                if (warn)
+                        *warn = os.conn == C_VERIFY_S || os.conn == C_VERIFY_T ?
+                                ABORTED_ONLINE_VERIFY : ABORTED_RESYNC;
                 ns.conn = C_CONNECTED;
         }
 
@@ -877,7 +971,8 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
                         ns.disk = mdev->new_state_tmp.disk;
                         ns.pdsk = mdev->new_state_tmp.pdsk;
                 } else {
-                        dev_alert(DEV, "Connection lost while negotiating, no data!\n");
+                        if (warn)
+                                *warn = CONNECTION_LOST_NEGOTIATING;
                         ns.disk = D_DISKLESS;
                         ns.pdsk = D_UNKNOWN;
                 }
@@ -959,16 +1054,16 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
                 ns.disk = disk_max;
 
         if (ns.disk < disk_min) {
-                dev_warn(DEV, "Implicitly set disk from %s to %s\n",
-                         drbd_disk_str(ns.disk), drbd_disk_str(disk_min));
+                if (warn)
+                        *warn = IMPLICITLY_UPGRADED_DISK;
                 ns.disk = disk_min;
         }
         if (ns.pdsk > pdsk_max)
                 ns.pdsk = pdsk_max;
 
         if (ns.pdsk < pdsk_min) {
-                dev_warn(DEV, "Implicitly set pdsk from %s to %s\n",
-                         drbd_disk_str(ns.pdsk), drbd_disk_str(pdsk_min));
+                if (warn)
+                        *warn = IMPLICITLY_UPGRADED_PDSK;
                 ns.pdsk = pdsk_min;
         }
 
@@ -1045,12 +1140,12 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
 {
         union drbd_state os;
         enum drbd_state_rv rv = SS_SUCCESS;
-        const char *warn_sync_abort = NULL;
+        enum sanitize_state_warnings ssw;
         struct after_state_chg_work *ascw;
 
         os = mdev->state;
 
-        ns = sanitize_state(mdev, os, ns, &warn_sync_abort);
+        ns = sanitize_state(mdev, os, ns, &ssw);
 
         if (ns.i == os.i)
                 return SS_NOTHING_TO_DO;
@@ -1076,8 +1171,7 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
                 return rv;
         }
 
-        if (warn_sync_abort)
-                dev_warn(DEV, "%s aborted.\n", warn_sync_abort);
+        print_sanitize_warnings(mdev, ssw);
 
         {
         char *pbp, pb[300];
@@ -1243,7 +1337,7 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
                 drbd_thread_stop_nowait(&mdev->receiver);
 
         /* Upon network failure, we need to restart the receiver. */
-        if (os.conn > C_TEAR_DOWN &&
+        if (os.conn > C_WF_CONNECTION &&
             ns.conn <= C_TEAR_DOWN && ns.conn >= C_TIMEOUT)
                 drbd_thread_restart_nowait(&mdev->receiver);
 
@@ -1251,6 +1345,15 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
         if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
                 drbd_resume_al(mdev);
 
+        /* remember last connect and attach times so request_timer_fn() won't
+         * kill newly established sessions while we are still trying to thaw
+         * previously frozen IO */
+        if (os.conn != C_WF_REPORT_PARAMS && ns.conn == C_WF_REPORT_PARAMS)
+                mdev->last_reconnect_jif = jiffies;
+        if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
+            ns.disk > D_NEGOTIATING)
+                mdev->last_reattach_jif = jiffies;
+
         ascw = kmalloc(sizeof(*ascw), GFP_ATOMIC);
         if (ascw) {
                 ascw->os = os;
@@ -1354,12 +1457,16 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
         /* Here we have the actions that are performed after a
            state change. This function might sleep */
 
+        if (os.disk <= D_NEGOTIATING && ns.disk > D_NEGOTIATING)
+                mod_timer(&mdev->request_timer, jiffies + HZ);
+
         nsm.i = -1;
         if (ns.susp_nod) {
                 if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
                         what = resend;
 
-                if (os.disk == D_ATTACHING && ns.disk > D_ATTACHING)
+                if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
+                    ns.disk > D_NEGOTIATING)
                         what = restart_frozen_disk_io;
 
                 if (what != nothing)
@@ -1408,7 +1515,7 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
         /* Do not change the order of the if above and the two below... */
         if (os.pdsk == D_DISKLESS && ns.pdsk > D_DISKLESS) {      /* attach on the peer */
                 drbd_send_uuids(mdev);
-                drbd_send_state(mdev);
+                drbd_send_state(mdev, ns);
         }
         /* No point in queuing send_bitmap if we don't have a connection
          * anymore, so check also the _current_ state, not only the new state
@@ -1441,11 +1548,11 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
         }
 
         if (ns.pdsk < D_INCONSISTENT && get_ldev(mdev)) {
-                if (ns.peer == R_PRIMARY && mdev->ldev->md.uuid[UI_BITMAP] == 0) {
+                if (os.peer == R_SECONDARY && ns.peer == R_PRIMARY &&
+                    mdev->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
                         drbd_uuid_new_current(mdev);
                         drbd_send_uuids(mdev);
                 }
-
                 /* D_DISKLESS Peer becomes secondary */
                 if (os.peer == R_PRIMARY && ns.peer == R_SECONDARY)
                         /* We may still be Primary ourselves.
@@ -1473,14 +1580,14 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
             os.disk == D_ATTACHING && ns.disk == D_NEGOTIATING) {
                 drbd_send_sizes(mdev, 0, 0);  /* to start sync... */
                 drbd_send_uuids(mdev);
-                drbd_send_state(mdev);
+                drbd_send_state(mdev, ns);
         }
 
         /* We want to pause/continue resync, tell peer. */
         if (ns.conn >= C_CONNECTED &&
              ((os.aftr_isp != ns.aftr_isp) ||
               (os.user_isp != ns.user_isp)))
-                drbd_send_state(mdev);
+                drbd_send_state(mdev, ns);
 
         /* In case one of the isp bits got set, suspend other devices. */
         if ((!os.aftr_isp && !os.peer_isp && !os.user_isp) &&
@@ -1490,10 +1597,10 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
         /* Make sure the peer gets informed about eventual state
            changes (ISP bits) while we were in WFReportParams. */
         if (os.conn == C_WF_REPORT_PARAMS && ns.conn >= C_CONNECTED)
-                drbd_send_state(mdev);
+                drbd_send_state(mdev, ns);
 
         if (os.conn != C_AHEAD && ns.conn == C_AHEAD)
-                drbd_send_state(mdev);
+                drbd_send_state(mdev, ns);
 
         /* We are in the progress to start a full sync... */
         if ((os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
@@ -1513,33 +1620,38 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
         /* first half of local IO error, failure to attach,
          * or administrative detach */
         if (os.disk != D_FAILED && ns.disk == D_FAILED) {
-                enum drbd_io_error_p eh;
-                int was_io_error;
+                enum drbd_io_error_p eh = EP_PASS_ON;
+                int was_io_error = 0;
                 /* corresponding get_ldev was in __drbd_set_state, to serialize
-                 * our cleanup here with the transition to D_DISKLESS,
-                 * so it is safe to dreference ldev here. */
-                eh = mdev->ldev->dc.on_io_error;
-                was_io_error = test_and_clear_bit(WAS_IO_ERROR, &mdev->flags);
-
-                /* current state still has to be D_FAILED,
-                 * there is only one way out: to D_DISKLESS,
-                 * and that may only happen after our put_ldev below. */
-                if (mdev->state.disk != D_FAILED)
-                        dev_err(DEV,
-                                "ASSERT FAILED: disk is %s during detach\n",
-                                drbd_disk_str(mdev->state.disk));
-
-                if (drbd_send_state(mdev))
-                        dev_warn(DEV, "Notified peer that I am detaching my disk\n");
-                else
-                        dev_err(DEV, "Sending state for detaching disk failed\n");
-
-                drbd_rs_cancel_all(mdev);
-
-                /* In case we want to get something to stable storage still,
-                 * this may be the last chance.
-                 * Following put_ldev may transition to D_DISKLESS. */
-                drbd_md_sync(mdev);
+                 * our cleanup here with the transition to D_DISKLESS.
+                 * But is is still not save to dreference ldev here, since
+                 * we might come from an failed Attach before ldev was set. */
+                if (mdev->ldev) {
+                        eh = mdev->ldev->dc.on_io_error;
+                        was_io_error = test_and_clear_bit(WAS_IO_ERROR, &mdev->flags);
+
+                        /* Immediately allow completion of all application IO, that waits
+                           for completion from the local disk. */
+                        tl_abort_disk_io(mdev);
+
+                        /* current state still has to be D_FAILED,
+                         * there is only one way out: to D_DISKLESS,
+                         * and that may only happen after our put_ldev below. */
+                        if (mdev->state.disk != D_FAILED)
+                                dev_err(DEV,
+                                        "ASSERT FAILED: disk is %s during detach\n",
+                                        drbd_disk_str(mdev->state.disk));
+
+                        if (ns.conn >= C_CONNECTED)
+                                drbd_send_state(mdev, ns);
+
+                        drbd_rs_cancel_all(mdev);
+
+                        /* In case we want to get something to stable storage still,
+                         * this may be the last chance.
+                         * Following put_ldev may transition to D_DISKLESS. */
+                        drbd_md_sync(mdev);
+                }
                 put_ldev(mdev);
 
                 if (was_io_error && eh == EP_CALL_HELPER)
@@ -1561,16 +1673,17 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
                 mdev->rs_failed = 0;
                 atomic_set(&mdev->rs_pending_cnt, 0);
 
-                if (drbd_send_state(mdev))
-                        dev_warn(DEV, "Notified peer that I'm now diskless.\n");
+                if (ns.conn >= C_CONNECTED)
+                        drbd_send_state(mdev, ns);
+
                 /* corresponding get_ldev in __drbd_set_state
                  * this may finally trigger drbd_ldev_destroy. */
                 put_ldev(mdev);
         }
 
         /* Notify peer that I had a local IO error, and did not detached.. */
-        if (os.disk == D_UP_TO_DATE && ns.disk == D_INCONSISTENT)
-                drbd_send_state(mdev);
+        if (os.disk == D_UP_TO_DATE && ns.disk == D_INCONSISTENT && ns.conn >= C_CONNECTED)
+                drbd_send_state(mdev, ns);
 
         /* Disks got bigger while they were detached */
         if (ns.disk > D_NEGOTIATING && ns.pdsk > D_NEGOTIATING &&
@@ -1588,7 +1701,13 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
         /* sync target done with resync.  Explicitly notify peer, even though
          * it should (at least for non-empty resyncs) already know itself. */
         if (os.disk < D_UP_TO_DATE && os.conn >= C_SYNC_SOURCE && ns.conn == C_CONNECTED)
-                drbd_send_state(mdev);
+                drbd_send_state(mdev, ns);
+
+        /* Wake up role changes, that were delayed because of connection establishing */
+        if (os.conn == C_WF_REPORT_PARAMS && ns.conn != C_WF_REPORT_PARAMS) {
+                clear_bit(STATE_SENT, &mdev->flags);
+                wake_up(&mdev->state_wait);
+        }
 
         /* This triggers bitmap writeout of potentially still unwritten pages
          * if the resync finished cleanly, or aborted because of peer disk
@@ -1598,8 +1717,8 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
          * No harm done if some bits change during this phase.
          */
         if (os.conn > C_CONNECTED && ns.conn <= C_CONNECTED && get_ldev(mdev)) {
-                drbd_queue_bitmap_io(mdev, &drbd_bm_write, NULL,
-                        "write from resync_finished", BM_LOCKED_SET_ALLOWED);
+                drbd_queue_bitmap_io(mdev, &drbd_bm_write_copy_pages, NULL,
+                        "write from resync_finished", BM_LOCKED_CHANGE_ALLOWED);
                 put_ldev(mdev);
         }
 
@@ -2057,7 +2176,11 @@ int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
 
         D_ASSERT(mdev->state.disk == D_UP_TO_DATE);
 
-        uuid = mdev->ldev->md.uuid[UI_BITMAP] + UUID_NEW_BM_OFFSET;
+        uuid = mdev->ldev->md.uuid[UI_BITMAP];
+        if (uuid && uuid != UUID_JUST_CREATED)
+                uuid = uuid + UUID_NEW_BM_OFFSET;
+        else
+                get_random_bytes(&uuid, sizeof(u64));
         drbd_uuid_set(mdev, UI_BITMAP, uuid);
         drbd_print_uuids(mdev, "updated sync UUID");
         drbd_md_sync(mdev);
@@ -2089,6 +2212,10 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
                 max_bio_size = DRBD_MAX_BIO_SIZE; /* ... multiple BIOs per peer_request */
         }
 
+        /* Never allow old drbd (up to 8.3.7) to see more than 32KiB */
+        if (mdev->agreed_pro_version <= 94)
+                max_bio_size = min_t(int, max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+
         p.d_size = cpu_to_be64(d_size);
         p.u_size = cpu_to_be64(u_size);
         p.c_size = cpu_to_be64(trigger_reply ? 0 : drbd_get_capacity(mdev->this_bdev));
@@ -2102,10 +2229,10 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
 }
 
 /**
- * drbd_send_state() - Sends the drbd state to the peer
+ * drbd_send_current_state() - Sends the drbd state to the peer
  * @mdev:       DRBD device.
  */
-int drbd_send_state(struct drbd_conf *mdev)
+int drbd_send_current_state(struct drbd_conf *mdev)
 {
         struct socket *sock;
         struct p_state p;
@@ -2131,6 +2258,37 @@ int drbd_send_state(struct drbd_conf *mdev)
         return ok;
 }
 
+/**
+ * drbd_send_state() - After a state change, sends the new state to the peer
+ * @mdev:       DRBD device.
+ * @state:      the state to send, not necessarily the current state.
+ *
+ * Each state change queues an "after_state_ch" work, which will eventually
+ * send the resulting new state to the peer. If more state changes happen
+ * between queuing and processing of the after_state_ch work, we still
+ * want to send each intermediary state in the order it occurred.
+ */
+int drbd_send_state(struct drbd_conf *mdev, union drbd_state state)
+{
+        struct socket *sock;
+        struct p_state p;
+        int ok = 0;
+
+        mutex_lock(&mdev->data.mutex);
+
+        p.state = cpu_to_be32(state.i);
+        sock = mdev->data.socket;
+
+        if (likely(sock != NULL)) {
+                ok = _drbd_send_cmd(mdev, sock, P_STATE,
+                                    (struct p_header80 *)&p, sizeof(p), 0);
+        }
+
+        mutex_unlock(&mdev->data.mutex);
+
+        return ok;
+}
+
 int drbd_send_state_req(struct drbd_conf *mdev,
         union drbd_state mask, union drbd_state val)
 {
@@ -2615,7 +2773,7 @@ static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio)
         struct bio_vec *bvec;
         int i;
         /* hint all but last page with MSG_MORE */
-        __bio_for_each_segment(bvec, bio, i, 0) {
+        bio_for_each_segment(bvec, bio, i) {
                 if (!_drbd_no_send_page(mdev, bvec->bv_page,
                                      bvec->bv_offset, bvec->bv_len,
                                      i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
@@ -2629,7 +2787,7 @@ static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
         struct bio_vec *bvec;
         int i;
         /* hint all but last page with MSG_MORE */
-        __bio_for_each_segment(bvec, bio, i, 0) {
+        bio_for_each_segment(bvec, bio, i) {
                 if (!_drbd_send_page(mdev, bvec->bv_page,
                                      bvec->bv_offset, bvec->bv_len,
                                      i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
@@ -2695,8 +2853,7 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
 
         p.sector   = cpu_to_be64(req->sector);
         p.block_id = (unsigned long)req;
-        p.seq_num  = cpu_to_be32(req->seq_num =
-                                 atomic_add_return(1, &mdev->packet_seq));
+        p.seq_num  = cpu_to_be32(atomic_add_return(1, &mdev->packet_seq));
 
         dp_flags = bio_flags_to_wire(mdev, req->master_bio->bi_rw);
 
@@ -2987,8 +3144,8 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
         atomic_set(&mdev->rs_sect_in, 0);
         atomic_set(&mdev->rs_sect_ev, 0);
         atomic_set(&mdev->ap_in_flight, 0);
+        atomic_set(&mdev->md_io_in_use, 0);
 
-        mutex_init(&mdev->md_io_mutex);
         mutex_init(&mdev->data.mutex);
         mutex_init(&mdev->meta.mutex);
         sema_init(&mdev->data.work.s, 0);
@@ -3126,6 +3283,10 @@ static void drbd_destroy_mempools(void)
 
         /* D_ASSERT(atomic_read(&drbd_pp_vacant)==0); */
 
+        if (drbd_md_io_bio_set)
+                bioset_free(drbd_md_io_bio_set);
+        if (drbd_md_io_page_pool)
+                mempool_destroy(drbd_md_io_page_pool);
         if (drbd_ee_mempool)
                 mempool_destroy(drbd_ee_mempool);
         if (drbd_request_mempool)
@@ -3139,6 +3300,8 @@ static void drbd_destroy_mempools(void)
         if (drbd_al_ext_cache)
                 kmem_cache_destroy(drbd_al_ext_cache);
 
+        drbd_md_io_bio_set   = NULL;
+        drbd_md_io_page_pool = NULL;
         drbd_ee_mempool      = NULL;
         drbd_request_mempool = NULL;
         drbd_ee_cache        = NULL;
@@ -3162,6 +3325,8 @@ static int drbd_create_mempools(void)
         drbd_bm_ext_cache    = NULL;
         drbd_al_ext_cache    = NULL;
         drbd_pp_pool         = NULL;
+        drbd_md_io_page_pool = NULL;
+        drbd_md_io_bio_set   = NULL;
 
         /* caches */
         drbd_request_cache = kmem_cache_create(
@@ -3185,6 +3350,16 @@ static int drbd_create_mempools(void)
                 goto Enomem;
 
         /* mempools */
+#ifdef COMPAT_HAVE_BIOSET_CREATE
+        drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0);
+        if (drbd_md_io_bio_set == NULL)
+                goto Enomem;
+#endif
+
+        drbd_md_io_page_pool = mempool_create_page_pool(DRBD_MIN_POOL_PAGES, 0);
+        if (drbd_md_io_page_pool == NULL)
+                goto Enomem;
+
         drbd_request_mempool = mempool_create(number,
                 mempool_alloc_slab, mempool_free_slab, drbd_request_cache);
         if (drbd_request_mempool == NULL)
@@ -3262,6 +3437,8 @@ static void drbd_delete_device(unsigned int minor)
         if (!mdev)
                 return;
 
+        del_timer_sync(&mdev->request_timer);
+
         /* paranoia asserts */
         if (mdev->open_cnt != 0)
                 dev_err(DEV, "open_cnt = %d in %s:%u", mdev->open_cnt,
@@ -3666,8 +3843,10 @@ void drbd_md_sync(struct drbd_conf *mdev)
         if (!get_ldev_if_state(mdev, D_FAILED))
                 return;
 
-        mutex_lock(&mdev->md_io_mutex);
-        buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
+        buffer = drbd_md_get_buffer(mdev);
+        if (!buffer)
+                goto out;
+
         memset(buffer, 0, 512);
 
         buffer->la_size = cpu_to_be64(drbd_get_capacity(mdev->this_bdev));
@@ -3698,7 +3877,8 @@ void drbd_md_sync(struct drbd_conf *mdev)
          * since we updated it on metadata. */
         mdev->ldev->md.la_size_sect = drbd_get_capacity(mdev->this_bdev);
 
-        mutex_unlock(&mdev->md_io_mutex);
+        drbd_md_put_buffer(mdev);
+out:
         put_ldev(mdev);
 }
 
@@ -3718,8 +3898,9 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
         if (!get_ldev_if_state(mdev, D_ATTACHING))
                 return ERR_IO_MD_DISK;
 
-        mutex_lock(&mdev->md_io_mutex);
-        buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
+        buffer = drbd_md_get_buffer(mdev);
+        if (!buffer)
+                goto out;
 
         if (!drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
                 /* NOTE: can't do normal error processing here as this is
@@ -3780,7 +3961,8 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
                 mdev->sync_conf.al_extents = 127;
 
  err:
-        mutex_unlock(&mdev->md_io_mutex);
+        drbd_md_put_buffer(mdev);
+ out:
         put_ldev(mdev);
 
         return rv;
@@ -4183,12 +4365,11 @@ const char *drbd_buildtag(void)
         static char buildtag[38] = "\0uilt-in";
 
         if (buildtag[0] == 0) {
-#ifdef CONFIG_MODULES
-                if (THIS_MODULE != NULL)
-                        sprintf(buildtag, "srcversion: %-24s", THIS_MODULE->srcversion);
-                else
+#ifdef MODULE
+                sprintf(buildtag, "srcversion: %-24s", THIS_MODULE->srcversion);
+#else
+                buildtag[0] = 'b';
 #endif
-                        buildtag[0] = 'b';
         }
 
         return buildtag;
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index abfaacaaf346..867bf1d82988 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -289,7 +289,7 @@ static int _try_outdate_peer_async(void *data)
         */
         spin_lock_irq(&mdev->req_lock);
         ns = mdev->state;
-        if (ns.conn < C_WF_REPORT_PARAMS) {
+        if (ns.conn < C_WF_REPORT_PARAMS && !test_bit(STATE_SENT, &mdev->flags)) {
                 ns.pdsk = nps;
                 _drbd_set_state(mdev, ns, CS_VERBOSE, NULL);
         }
@@ -432,7 +432,7 @@ drbd_set_role(struct drbd_conf *mdev, enum drbd_role new_role, int force)
                 /* if this was forced, we should consider sync */
                 if (forced)
                         drbd_send_uuids(mdev);
-                drbd_send_state(mdev);
+                drbd_send_current_state(mdev);
         }
 
         drbd_md_sync(mdev);
@@ -845,9 +845,10 @@ void drbd_reconsider_max_bio_size(struct drbd_conf *mdev)
            Because new from 8.3.8 onwards the peer can use multiple
            BIOs for a single peer_request */
         if (mdev->state.conn >= C_CONNECTED) {
-                if (mdev->agreed_pro_version < 94)
-                        peer = mdev->peer_max_bio_size;
-                else if (mdev->agreed_pro_version == 94)
+                if (mdev->agreed_pro_version < 94) {
+                        peer = min_t(int, mdev->peer_max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+                        /* Correct old drbd (up to 8.3.7) if it believes it can do more than 32KiB */
+                } else if (mdev->agreed_pro_version == 94)
                         peer = DRBD_MAX_SIZE_H80_PACKET;
                 else /* drbd 8.3.8 onwards */
                         peer = DRBD_MAX_BIO_SIZE;
@@ -1032,7 +1033,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
                 dev_err(DEV, "max capacity %llu smaller than disk size %llu\n",
                         (unsigned long long) drbd_get_max_capacity(nbc),
                         (unsigned long long) nbc->dc.disk_size);
-                retcode = ERR_DISK_TO_SMALL;
+                retcode = ERR_DISK_TOO_SMALL;
                 goto fail;
         }
 
@@ -1046,7 +1047,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
         }
 
         if (drbd_get_capacity(nbc->md_bdev) < min_md_device_sectors) {
-                retcode = ERR_MD_DISK_TO_SMALL;
+                retcode = ERR_MD_DISK_TOO_SMALL;
                 dev_warn(DEV, "refusing attach: md-device too small, "
                      "at least %llu sectors needed for this meta-disk type\n",
                      (unsigned long long) min_md_device_sectors);
@@ -1057,7 +1058,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
          * (we may currently be R_PRIMARY with no local disk...) */
         if (drbd_get_max_capacity(nbc) <
             drbd_get_capacity(mdev->this_bdev)) {
-                retcode = ERR_DISK_TO_SMALL;
+                retcode = ERR_DISK_TOO_SMALL;
                 goto fail;
         }
 
@@ -1138,7 +1139,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
         if (drbd_md_test_flag(nbc, MDF_CONSISTENT) &&
             drbd_new_dev_size(mdev, nbc, 0) < nbc->md.la_size_sect) {
                 dev_warn(DEV, "refusing to truncate a consistent device\n");
-                retcode = ERR_DISK_TO_SMALL;
+                retcode = ERR_DISK_TOO_SMALL;
                 goto force_diskless_dec;
         }
 
@@ -1336,17 +1337,34 @@ static int drbd_nl_detach(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
 {
         enum drbd_ret_code retcode;
         int ret;
+        struct detach dt = {};
+
+        if (!detach_from_tags(mdev, nlp->tag_list, &dt)) {
+                reply->ret_code = ERR_MANDATORY_TAG;
+                goto out;
+        }
+
+        if (dt.detach_force) {
+                drbd_force_state(mdev, NS(disk, D_FAILED));
+                reply->ret_code = SS_SUCCESS;
+                goto out;
+        }
+
         drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */
+        drbd_md_get_buffer(mdev); /* make sure there is no in-flight meta-data IO */
         retcode = drbd_request_state(mdev, NS(disk, D_FAILED));
+        drbd_md_put_buffer(mdev);
         /* D_FAILED will transition to DISKLESS. */
         ret = wait_event_interruptible(mdev->misc_wait,
                         mdev->state.disk != D_FAILED);
         drbd_resume_io(mdev);
+
         if ((int)retcode == (int)SS_IS_DISKLESS)
                 retcode = SS_NOTHING_TO_DO;
         if (ret)
                 retcode = ERR_INTR;
         reply->ret_code = retcode;
+out:
         return 0;
 }
 
@@ -1711,7 +1729,7 @@ static int drbd_nl_resize(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
 
         if (rs.no_resync && mdev->agreed_pro_version < 93) {
                 retcode = ERR_NEED_APV_93;
-                goto fail;
+                goto fail_ldev;
         }
 
         if (mdev->ldev->known_size != drbd_get_capacity(mdev->ldev->backing_bdev))
@@ -1738,6 +1756,10 @@ static int drbd_nl_resize(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
  fail:
         reply->ret_code = retcode;
         return 0;
+
+ fail_ldev:
+        put_ldev(mdev);
+        goto fail;
 }
 
 static int drbd_nl_syncer_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
@@ -1941,6 +1963,7 @@ static int drbd_nl_invalidate(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nl
 
         /* If there is still bitmap IO pending, probably because of a previous
          * resync just being finished, wait for it before requesting a new resync. */
+        drbd_suspend_io(mdev);
         wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
 
         retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T), CS_ORDERED);
@@ -1959,6 +1982,7 @@ static int drbd_nl_invalidate(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nl
 
                 retcode = drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T));
         }
+        drbd_resume_io(mdev);
 
         reply->ret_code = retcode;
         return 0;
@@ -1980,6 +2004,7 @@ static int drbd_nl_invalidate_peer(struct drbd_conf *mdev, struct drbd_nl_cfg_re
 
         /* If there is still bitmap IO pending, probably because of a previous
          * resync just being finished, wait for it before requesting a new resync. */
+        drbd_suspend_io(mdev);
         wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
 
         retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_S), CS_ORDERED);
@@ -1998,6 +2023,7 @@ static int drbd_nl_invalidate_peer(struct drbd_conf *mdev, struct drbd_nl_cfg_re
                 } else
                         retcode = drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_S));
         }
+        drbd_resume_io(mdev);
 
         reply->ret_code = retcode;
         return 0;
@@ -2170,11 +2196,13 @@ static int drbd_nl_start_ov(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
 
         /* If there is still bitmap IO pending, e.g. previous resync or verify
          * just being finished, wait for it before requesting a new resync. */
+        drbd_suspend_io(mdev);
         wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
 
         /* w_make_ov_request expects position to be aligned */
         mdev->ov_start_sector = args.start_sector & ~BM_SECT_PER_BIT;
         reply->ret_code = drbd_request_state(mdev,NS(conn,C_VERIFY_S));
+        drbd_resume_io(mdev);
         return 0;
 }
 
diff --git a/drivers/block/drbd/drbd_proc.c b/drivers/block/drbd/drbd_proc.c
index 2959cdfb77f5..869bada2ed06 100644
--- a/drivers/block/drbd/drbd_proc.c
+++ b/drivers/block/drbd/drbd_proc.c
@@ -52,7 +52,7 @@ void seq_printf_with_thousands_grouping(struct seq_file *seq, long v)
         if (unlikely(v >= 1000000)) {
                 /* cool: > GiByte/s */
                 seq_printf(seq, "%ld,", v / 1000000);
-                v /= 1000000;
+                v %= 1000000;
                 seq_printf(seq, "%03ld,%03ld", v/1000, v % 1000);
         } else if (likely(v >= 1000))
                 seq_printf(seq, "%ld,%03ld", v/1000, v % 1000);
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 43beaca53179..1d088c478150 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -466,6 +466,7 @@ static int drbd_accept(struct drbd_conf *mdev, const char **what,
                 goto out;
         }
         (*newsock)->ops  = sock->ops;
+        __module_get((*newsock)->ops->owner);
 
 out:
         return err;
@@ -750,6 +751,7 @@ static int drbd_connect(struct drbd_conf *mdev)
 {
         struct socket *s, *sock, *msock;
         int try, h, ok;
+        enum drbd_state_rv rv;
 
         D_ASSERT(!mdev->data.socket);
 
@@ -888,25 +890,32 @@ retry:
                 }
         }
 
-        if (drbd_request_state(mdev, NS(conn, C_WF_REPORT_PARAMS)) < SS_SUCCESS)
-                return 0;
-
         sock->sk->sk_sndtimeo = mdev->net_conf->timeout*HZ/10;
         sock->sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT;
 
         atomic_set(&mdev->packet_seq, 0);
         mdev->peer_seq = 0;
 
-        drbd_thread_start(&mdev->asender);
-
         if (drbd_send_protocol(mdev) == -1)
                 return -1;
+        set_bit(STATE_SENT, &mdev->flags);
         drbd_send_sync_param(mdev, &mdev->sync_conf);
         drbd_send_sizes(mdev, 0, 0);
         drbd_send_uuids(mdev);
-        drbd_send_state(mdev);
+        drbd_send_current_state(mdev);
         clear_bit(USE_DEGR_WFC_T, &mdev->flags);
         clear_bit(RESIZE_PENDING, &mdev->flags);
+
+        spin_lock_irq(&mdev->req_lock);
+        rv = _drbd_set_state(_NS(mdev, conn, C_WF_REPORT_PARAMS), CS_VERBOSE, NULL);
+        if (mdev->state.conn != C_WF_REPORT_PARAMS)
+                clear_bit(STATE_SENT, &mdev->flags);
+        spin_unlock_irq(&mdev->req_lock);
+
+        if (rv < SS_SUCCESS)
+                return 0;
+
+        drbd_thread_start(&mdev->asender);
         mod_timer(&mdev->request_timer, jiffies + HZ); /* just start it here. */
 
         return 1;
@@ -957,7 +966,7 @@ static void drbd_flush(struct drbd_conf *mdev)
                 rv = blkdev_issue_flush(mdev->ldev->backing_bdev, GFP_KERNEL,
                                         NULL);
                 if (rv) {
-                        dev_err(DEV, "local disk flush failed with status %d\n", rv);
+                        dev_info(DEV, "local disk flush failed with status %d\n", rv);
                         /* would rather check on EOPNOTSUPP, but that is not reliable.
                          * don't try again for ANY return value != 0
                          * if (rv == -EOPNOTSUPP) */
@@ -1001,13 +1010,14 @@ 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)) {
+                    (test_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags) || ev & EV_CLEANUP)) {
                         if (!(ev & EV_CLEANUP)) {
                                 spin_unlock(&mdev->epoch_lock);
                                 drbd_send_b_ack(mdev, epoch->barrier_nr, epoch_size);
                                 spin_lock(&mdev->epoch_lock);
                         }
-                        dec_unacked(mdev);
+                        if (test_bit(DE_HAVE_BARRIER_NUMBER, &epoch->flags))
+                                dec_unacked(mdev);
 
                         if (mdev->current_epoch != epoch) {
                                 next_epoch = list_entry(epoch->list.next, struct drbd_epoch, list);
@@ -1096,7 +1106,11 @@ int drbd_submit_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e,
         /* In most cases, we will only need one bio.  But in case the lower
          * level restrictions happen to be different at this offset on this
          * side than those of the sending peer, we may need to submit the
-         * request in more than one bio. */
+         * request in more than one bio.
+         *
+         * Plain bio_alloc is good enough here, this is no DRBD internally
+         * generated bio, but a bio allocated on behalf of the peer.
+         */
 next_bio:
         bio = bio_alloc(GFP_NOIO, nr_pages);
         if (!bio) {
@@ -1583,6 +1597,24 @@ static int e_send_discard_ack(struct drbd_conf *mdev, struct drbd_work *w, int u
         return ok;
 }
 
+static bool overlapping_resync_write(struct drbd_conf *mdev, struct drbd_epoch_entry *data_e)
+{
+
+        struct drbd_epoch_entry *rs_e;
+        bool rv = 0;
+
+        spin_lock_irq(&mdev->req_lock);
+        list_for_each_entry(rs_e, &mdev->sync_ee, w.list) {
+                if (overlaps(data_e->sector, data_e->size, rs_e->sector, rs_e->size)) {
+                        rv = 1;
+                        break;
+                }
+        }
+        spin_unlock_irq(&mdev->req_lock);
+
+        return rv;
+}
+
 /* Called from receive_Data.
  * Synchronize packets on sock with packets on msock.
  *
@@ -1826,6 +1858,9 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
         list_add(&e->w.list, &mdev->active_ee);
         spin_unlock_irq(&mdev->req_lock);
 
+        if (mdev->state.conn == C_SYNC_TARGET)
+                wait_event(mdev->ee_wait, !overlapping_resync_write(mdev, e));
+
         switch (mdev->net_conf->wire_protocol) {
         case DRBD_PROT_C:
                 inc_unacked(mdev);
@@ -2420,7 +2455,7 @@ static int drbd_uuid_compare(struct drbd_conf *mdev, int *rule_nr) __must_hold(l
                         mdev->p_uuid[UI_BITMAP] = mdev->p_uuid[UI_HISTORY_START];
                         mdev->p_uuid[UI_HISTORY_START] = mdev->p_uuid[UI_HISTORY_START + 1];
 
-                        dev_info(DEV, "Did not got last syncUUID packet, corrected:\n");
+                        dev_info(DEV, "Lost last syncUUID packet, corrected:\n");
                         drbd_uuid_dump(mdev, "peer", mdev->p_uuid, mdev->p_uuid[UI_SIZE], mdev->p_uuid[UI_FLAGS]);
 
                         return -1;
@@ -2806,10 +2841,10 @@ static int receive_SyncParam(struct drbd_conf *mdev, enum drbd_packets cmd, unsi
 
         if (apv >= 88) {
                 if (apv == 88) {
-                        if (data_size > SHARED_SECRET_MAX) {
-                                dev_err(DEV, "verify-alg too long, "
-                                    "peer wants %u, accepting only %u byte\n",
-                                                data_size, SHARED_SECRET_MAX);
+                        if (data_size > SHARED_SECRET_MAX || data_size == 0) {
+                                dev_err(DEV, "verify-alg of wrong size, "
+                                        "peer wants %u, accepting only up to %u byte\n",
+                                        data_size, SHARED_SECRET_MAX);
                                 return false;
                         }
 
@@ -3168,9 +3203,20 @@ static int receive_state(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
         os = ns = mdev->state;
         spin_unlock_irq(&mdev->req_lock);
 
-        /* peer says his disk is uptodate, while we think it is inconsistent,
-         * and this happens while we think we have a sync going on. */
-        if (os.pdsk == D_INCONSISTENT && real_peer_disk == D_UP_TO_DATE &&
+        /* If some other part of the code (asender thread, timeout)
+         * already decided to close the connection again,
+         * we must not "re-establish" it here. */
+        if (os.conn <= C_TEAR_DOWN)
+                return false;
+
+        /* If this is the "end of sync" confirmation, usually the peer disk
+         * transitions from D_INCONSISTENT to D_UP_TO_DATE. For empty (0 bits
+         * set) resync started in PausedSyncT, or if the timing of pause-/
+         * unpause-sync events has been "just right", the peer disk may
+         * transition from D_CONSISTENT to D_UP_TO_DATE as well.
+         */
+        if ((os.pdsk == D_INCONSISTENT || os.pdsk == D_CONSISTENT) &&
+            real_peer_disk == D_UP_TO_DATE &&
             os.conn > C_CONNECTED && os.disk == D_UP_TO_DATE) {
                 /* If we are (becoming) SyncSource, but peer is still in sync
                  * preparation, ignore its uptodate-ness to avoid flapping, it
@@ -3288,7 +3334,7 @@ static int receive_state(struct drbd_conf *mdev, enum drbd_packets cmd, unsigned
                         /* Nowadays only used when forcing a node into primary role and
                            setting its disk to UpToDate with that */
                         drbd_send_uuids(mdev);
-                        drbd_send_state(mdev);
+                        drbd_send_current_state(mdev);
                 }
         }
 
@@ -3776,6 +3822,13 @@ static void drbd_disconnect(struct drbd_conf *mdev)
         if (mdev->state.conn == C_STANDALONE)
                 return;
 
+        /* We are about to start the cleanup after connection loss.
+         * Make sure drbd_make_request knows about that.
+         * Usually we should be in some network failure state already,
+         * but just in case we are not, we fix it up here.
+         */
+        drbd_force_state(mdev, NS(conn, C_NETWORK_FAILURE));
+
         /* asender does not clean up anything. it must not interfere, either */
         drbd_thread_stop(&mdev->asender);
         drbd_free_sock(mdev);
@@ -3803,8 +3856,6 @@ static void drbd_disconnect(struct drbd_conf *mdev)
         atomic_set(&mdev->rs_pending_cnt, 0);
         wake_up(&mdev->misc_wait);
 
-        del_timer(&mdev->request_timer);
-
         /* make sure syncer is stopped and w_resume_next_sg queued */
         del_timer_sync(&mdev->resync_timer);
         resync_timer_fn((unsigned long)mdev);
@@ -4433,7 +4484,7 @@ static int got_BarrierAck(struct drbd_conf *mdev, struct p_header80 *h)
 
         if (mdev->state.conn == C_AHEAD &&
             atomic_read(&mdev->ap_in_flight) == 0 &&
-            !test_and_set_bit(AHEAD_TO_SYNC_SOURCE, &mdev->current_epoch->flags)) {
+            !test_and_set_bit(AHEAD_TO_SYNC_SOURCE, &mdev->flags)) {
                 mdev->start_resync_timer.expires = jiffies + HZ;
                 add_timer(&mdev->start_resync_timer);
         }
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 4a0f314086e5..9c5c84946b05 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -37,6 +37,7 @@ static void _drbd_start_io_acct(struct drbd_conf *mdev, struct drbd_request *req
         const int rw = bio_data_dir(bio);
         int cpu;
         cpu = part_stat_lock();
+        part_round_stats(cpu, &mdev->vdisk->part0);
         part_stat_inc(cpu, &mdev->vdisk->part0, ios[rw]);
         part_stat_add(cpu, &mdev->vdisk->part0, sectors[rw], bio_sectors(bio));
         part_inc_in_flight(&mdev->vdisk->part0, rw);
@@ -214,8 +215,7 @@ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
 {
         const unsigned long s = req->rq_state;
         struct drbd_conf *mdev = req->mdev;
-        /* only WRITES may end up here without a master bio (on barrier ack) */
-        int rw = req->master_bio ? bio_data_dir(req->master_bio) : WRITE;
+        int rw = req->rq_state & RQ_WRITE ? WRITE : READ;
 
         /* we must not complete the master bio, while it is
          *      still being processed by _drbd_send_zc_bio (drbd_send_dblock)
@@ -230,7 +230,7 @@ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
                 return;
         if (s & RQ_NET_PENDING)
                 return;
-        if (s & RQ_LOCAL_PENDING)
+        if (s & RQ_LOCAL_PENDING && !(s & RQ_LOCAL_ABORTED))
                 return;
 
         if (req->master_bio) {
@@ -277,6 +277,9 @@ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
                 req->master_bio = NULL;
         }
 
+        if (s & RQ_LOCAL_PENDING)
+                return;
+
         if ((s & RQ_NET_MASK) == 0 || (s & RQ_NET_DONE)) {
                 /* this is disconnected (local only) operation,
                  * or protocol C P_WRITE_ACK,
@@ -429,7 +432,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 break;
 
         case completed_ok:
-                if (bio_data_dir(req->master_bio) == WRITE)
+                if (req->rq_state & RQ_WRITE)
                         mdev->writ_cnt += req->size>>9;
                 else
                         mdev->read_cnt += req->size>>9;
@@ -438,7 +441,14 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 req->rq_state &= ~RQ_LOCAL_PENDING;
 
                 _req_may_be_done_not_susp(req, m);
-                put_ldev(mdev);
+                break;
+
+        case abort_disk_io:
+                req->rq_state |= RQ_LOCAL_ABORTED;
+                if (req->rq_state & RQ_WRITE)
+                        _req_may_be_done_not_susp(req, m);
+                else
+                        goto goto_queue_for_net_read;
                 break;
 
         case write_completed_with_error:
@@ -447,7 +457,6 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 
                 __drbd_chk_io_error(mdev, false);
                 _req_may_be_done_not_susp(req, m);
-                put_ldev(mdev);
                 break;
 
         case read_ahead_completed_with_error:
@@ -455,7 +464,6 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 req->rq_state |= RQ_LOCAL_COMPLETED;
                 req->rq_state &= ~RQ_LOCAL_PENDING;
                 _req_may_be_done_not_susp(req, m);
-                put_ldev(mdev);
                 break;
 
         case read_completed_with_error:
@@ -467,7 +475,8 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 D_ASSERT(!(req->rq_state & RQ_NET_MASK));
 
                 __drbd_chk_io_error(mdev, false);
-                put_ldev(mdev);
+
+        goto_queue_for_net_read:
 
                 /* no point in retrying if there is no good remote data,
                  * or we have no connection. */
@@ -556,10 +565,8 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 drbd_queue_work(&mdev->data.work, &req->w);
                 break;
 
-        case oos_handed_to_network:
-                /* actually the same */
+        case read_retry_remote_canceled:
         case send_canceled:
-                /* treat it the same */
         case send_failed:
                 /* real cleanup will be done from tl_clear.  just update flags
                  * so it is no longer marked as on the worker queue */
@@ -589,17 +596,17 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 }
                 req->rq_state &= ~RQ_NET_QUEUED;
                 req->rq_state |= RQ_NET_SENT;
-                /* because _drbd_send_zc_bio could sleep, and may want to
-                 * dereference the bio even after the "write_acked_by_peer" and
-                 * "completed_ok" events came in, once we return from
-                 * _drbd_send_zc_bio (drbd_send_dblock), we have to check
-                 * whether it is done already, and end it.  */
                 _req_may_be_done_not_susp(req, m);
                 break;
 
-        case read_retry_remote_canceled:
+        case oos_handed_to_network:
+                /* Was not set PENDING, no longer QUEUED, so is now DONE
+                 * as far as this connection is concerned. */
                 req->rq_state &= ~RQ_NET_QUEUED;
-                /* fall through, in case we raced with drbd_disconnect */
+                req->rq_state |= RQ_NET_DONE;
+                _req_may_be_done_not_susp(req, m);
+                break;
+
         case connection_lost_while_pending:
                 /* transfer log cleanup after connection loss */
                 /* assert something? */
@@ -616,8 +623,6 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                         _req_may_be_done(req, m); /* Allowed while state.susp */
                 break;
 
-        case write_acked_by_peer_and_sis:
-                req->rq_state |= RQ_NET_SIS;
         case conflict_discarded_by_peer:
                 /* for discarded conflicting writes of multiple primaries,
                  * there is no need to keep anything in the tl, potential
@@ -628,18 +633,15 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                               (unsigned long long)req->sector, req->size);
                 req->rq_state |= RQ_NET_DONE;
                 /* fall through */
+        case write_acked_by_peer_and_sis:
         case write_acked_by_peer:
+                if (what == write_acked_by_peer_and_sis)
+                        req->rq_state |= RQ_NET_SIS;
                 /* protocol C; successfully written on peer.
-                 * Nothing to do here.
+                 * Nothing more to do here.
                  * We want to keep the tl in place for all protocols, to cater
-                 * for volatile write-back caches on lower level devices.
-                 *
-                 * A barrier request is expected to have forced all prior
-                 * requests onto stable storage, so completion of a barrier
-                 * request could set NET_DONE right here, and not wait for the
-                 * P_BARRIER_ACK, but that is an unnecessary optimization. */
+                 * for volatile write-back caches on lower level devices. */
 
-                /* this makes it effectively the same as for: */
         case recv_acked_by_peer:
                 /* protocol B; pretends to be successfully written on peer.
                  * see also notes above in handed_over_to_network about
@@ -773,6 +775,7 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio, uns
         int local, remote, send_oos = 0;
         int err = -EIO;
         int ret = 0;
+        union drbd_state s;
 
         /* allocate outside of all locks; */
         req = drbd_req_new(mdev, bio);
@@ -834,8 +837,9 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio, uns
                 drbd_al_begin_io(mdev, sector);
         }
 
-        remote = remote && drbd_should_do_remote(mdev->state);
-        send_oos = rw == WRITE && drbd_should_send_oos(mdev->state);
+        s = mdev->state;
+        remote = remote && drbd_should_do_remote(s);
+        send_oos = rw == WRITE && drbd_should_send_oos(s);
         D_ASSERT(!(remote && send_oos));
 
         if (!(local || remote) && !is_susp(mdev->state)) {
@@ -867,7 +871,7 @@ allocate_barrier:
 
         if (is_susp(mdev->state)) {
                 /* If we got suspended, use the retry mechanism of
-                   generic_make_request() to restart processing of this
+                   drbd_make_request() to restart processing of this
                    bio. In the next call to drbd_make_request
                    we sleep in inc_ap_bio() */
                 ret = 1;
@@ -1091,7 +1095,6 @@ void drbd_make_request(struct request_queue *q, struct bio *bio)
          */
         D_ASSERT(bio->bi_size > 0);
         D_ASSERT((bio->bi_size & 0x1ff) == 0);
-        D_ASSERT(bio->bi_idx == 0);
 
         /* to make some things easier, force alignment of requests within the
          * granularity of our hash tables */
@@ -1099,8 +1102,9 @@ void drbd_make_request(struct request_queue *q, struct bio *bio)
         e_enr = (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT;
 
         if (likely(s_enr == e_enr)) {
-                inc_ap_bio(mdev, 1);
-                drbd_make_request_common(mdev, bio, start_time);
+                do {
+                        inc_ap_bio(mdev, 1);
+                } while (drbd_make_request_common(mdev, bio, start_time));
                 return;
         }
 
@@ -1196,36 +1200,66 @@ void request_timer_fn(unsigned long data)
         struct drbd_conf *mdev = (struct drbd_conf *) data;
         struct drbd_request *req; /* oldest request */
         struct list_head *le;
-        unsigned long et = 0; /* effective timeout = ko_count * timeout */
+        unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */
+        unsigned long now;
 
         if (get_net_conf(mdev)) {
-                et = mdev->net_conf->timeout*HZ/10 * mdev->net_conf->ko_count;
+                if (mdev->state.conn >= C_WF_REPORT_PARAMS)
+                        ent = mdev->net_conf->timeout*HZ/10
+                                * mdev->net_conf->ko_count;
                 put_net_conf(mdev);
         }
-        if (!et || mdev->state.conn < C_WF_REPORT_PARAMS)
+        if (get_ldev(mdev)) { /* implicit state.disk >= D_INCONSISTENT */
+                dt = mdev->ldev->dc.disk_timeout * HZ / 10;
+                put_ldev(mdev);
+        }
+        et = min_not_zero(dt, ent);
+
+        if (!et)
                 return; /* Recurring timer stopped */
 
+        now = jiffies;
+
         spin_lock_irq(&mdev->req_lock);
         le = &mdev->oldest_tle->requests;
         if (list_empty(le)) {
                 spin_unlock_irq(&mdev->req_lock);
-                mod_timer(&mdev->request_timer, jiffies + et);
+                mod_timer(&mdev->request_timer, now + et);
                 return;
         }
 
         le = le->prev;
         req = list_entry(le, struct drbd_request, tl_requests);
-        if (time_is_before_eq_jiffies(req->start_time + et)) {
-                if (req->rq_state & RQ_NET_PENDING) {
-                        dev_warn(DEV, "Remote failed to finish a request within ko-count * timeout\n");
-                        _drbd_set_state(_NS(mdev, conn, C_TIMEOUT), CS_VERBOSE, NULL);
-                } else {
-                        dev_warn(DEV, "Local backing block device frozen?\n");
-                        mod_timer(&mdev->request_timer, jiffies + et);
-                }
-        } else {
-                mod_timer(&mdev->request_timer, req->start_time + et);
-        }
 
+        /* The request is considered timed out, if
+         * - we have some effective timeout from the configuration,
+         *   with above state restrictions applied,
+         * - the oldest request is waiting for a response from the network
+         *   resp. the local disk,
+         * - the oldest request is in fact older than the effective timeout,
+         * - the connection was established (resp. disk was attached)
+         *   for longer than the timeout already.
+         * Note that for 32bit jiffies and very stable connections/disks,
+         * we may have a wrap around, which is catched by
+         *   !time_in_range(now, last_..._jif, last_..._jif + timeout).
+         *
+         * Side effect: once per 32bit wrap-around interval, which means every
+         * ~198 days with 250 HZ, we have a window where the timeout would need
+         * to expire twice (worst case) to become effective. Good enough.
+         */
+        if (ent && req->rq_state & RQ_NET_PENDING &&
+                 time_after(now, req->start_time + ent) &&
+                !time_in_range(now, mdev->last_reconnect_jif, mdev->last_reconnect_jif + ent)) {
+                dev_warn(DEV, "Remote failed to finish a request within ko-count * timeout\n");
+                _drbd_set_state(_NS(mdev, conn, C_TIMEOUT), CS_VERBOSE | CS_HARD, NULL);
+        }
+        if (dt && req->rq_state & RQ_LOCAL_PENDING &&
+                 time_after(now, req->start_time + dt) &&
+                !time_in_range(now, mdev->last_reattach_jif, mdev->last_reattach_jif + dt)) {
+                dev_warn(DEV, "Local backing device failed to meet the disk-timeout\n");
+                __drbd_chk_io_error(mdev, 1);
+        }
+        nt = (time_after(now, req->start_time + et) ? now : req->start_time) + et;
         spin_unlock_irq(&mdev->req_lock);
+        mod_timer(&mdev->request_timer, nt);
 }
diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h
index 68a234a5fdc5..3d2111919486 100644
--- a/drivers/block/drbd/drbd_req.h
+++ b/drivers/block/drbd/drbd_req.h
@@ -105,6 +105,7 @@ enum drbd_req_event {
         read_completed_with_error,
         read_ahead_completed_with_error,
         write_completed_with_error,
+        abort_disk_io,
         completed_ok,
         resend,
         fail_frozen_disk_io,
@@ -118,18 +119,21 @@ enum drbd_req_event {
  * same time, so we should hold the request lock anyways.
  */
 enum drbd_req_state_bits {
-        /* 210
-         * 000: no local possible
-         * 001: to be submitted
+        /* 3210
+         * 0000: no local possible
+         * 0001: to be submitted
          *    UNUSED, we could map: 011: submitted, completion still pending
-         * 110: completed ok
-         * 010: completed with error
+         * 0110: completed ok
+         * 0010: completed with error
+         * 1001: Aborted (before completion)
+         * 1x10: Aborted and completed -> free
          */
         __RQ_LOCAL_PENDING,
         __RQ_LOCAL_COMPLETED,
         __RQ_LOCAL_OK,
+        __RQ_LOCAL_ABORTED,
 
-        /* 76543
+        /* 87654
          * 00000: no network possible
          * 00001: to be send
          * 00011: to be send, on worker queue
@@ -199,8 +203,9 @@ enum drbd_req_state_bits {
 #define RQ_LOCAL_PENDING   (1UL << __RQ_LOCAL_PENDING)
 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED)
 #define RQ_LOCAL_OK        (1UL << __RQ_LOCAL_OK)
+#define RQ_LOCAL_ABORTED   (1UL << __RQ_LOCAL_ABORTED)
 
-#define RQ_LOCAL_MASK      ((RQ_LOCAL_OK << 1)-1) /* 0x07 */
+#define RQ_LOCAL_MASK      ((RQ_LOCAL_ABORTED << 1)-1)
 
 #define RQ_NET_PENDING     (1UL << __RQ_NET_PENDING)
 #define RQ_NET_QUEUED      (1UL << __RQ_NET_QUEUED)
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 4d3e6f6213ba..620c70ff2231 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -70,11 +70,29 @@ rwlock_t global_state_lock;
 void drbd_md_io_complete(struct bio *bio, int error)
 {
         struct drbd_md_io *md_io;
+        struct drbd_conf *mdev;
 
         md_io = (struct drbd_md_io *)bio->bi_private;
+        mdev = container_of(md_io, struct drbd_conf, md_io);
+
         md_io->error = error;
 
-        complete(&md_io->event);
+        /* We grabbed an extra reference in _drbd_md_sync_page_io() to be able
+         * to timeout on the lower level device, and eventually detach from it.
+         * If this io completion runs after that timeout expired, this
+         * drbd_md_put_buffer() may allow us to finally try and re-attach.
+         * During normal operation, this only puts that extra reference
+         * down to 1 again.
+         * Make sure we first drop the reference, and only then signal
+         * completion, or we may (in drbd_al_read_log()) cycle so fast into the
+         * next drbd_md_sync_page_io(), that we trigger the
+         * ASSERT(atomic_read(&mdev->md_io_in_use) == 1) there.
+         */
+        drbd_md_put_buffer(mdev);
+        md_io->done = 1;
+        wake_up(&mdev->misc_wait);
+        bio_put(bio);
+        put_ldev(mdev);
 }
 
 /* reads on behalf of the partner,
@@ -226,6 +244,7 @@ void drbd_endio_pri(struct bio *bio, int error)
         spin_lock_irqsave(&mdev->req_lock, flags);
         __req_mod(req, what, &m);
         spin_unlock_irqrestore(&mdev->req_lock, flags);
+        put_ldev(mdev);
 
         if (m.bio)
                 complete_master_bio(mdev, &m);
@@ -290,7 +309,7 @@ void drbd_csum_bio(struct drbd_conf *mdev, struct crypto_hash *tfm, struct bio *
         sg_init_table(&sg, 1);
         crypto_hash_init(&desc);
 
-        __bio_for_each_segment(bvec, bio, i, 0) {
+        bio_for_each_segment(bvec, bio, i) {
                 sg_set_page(&sg, bvec->bv_page, bvec->bv_len, bvec->bv_offset);
                 crypto_hash_update(&desc, &sg, sg.length);
         }
@@ -728,7 +747,7 @@ int w_start_resync(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
         }
 
         drbd_start_resync(mdev, C_SYNC_SOURCE);
-        clear_bit(AHEAD_TO_SYNC_SOURCE, &mdev->current_epoch->flags);
+        clear_bit(AHEAD_TO_SYNC_SOURCE, &mdev->flags);
         return 1;
 }
 
@@ -1519,14 +1538,14 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
         }
 
         drbd_state_lock(mdev);
-
+        write_lock_irq(&global_state_lock);
         if (!get_ldev_if_state(mdev, D_NEGOTIATING)) {
+                write_unlock_irq(&global_state_lock);
                 drbd_state_unlock(mdev);
                 return;
         }
 
-        write_lock_irq(&global_state_lock);
-        ns = mdev->state;
+        ns.i = mdev->state.i;
 
         ns.aftr_isp = !_drbd_may_sync_now(mdev);