1 files changed, 22 insertions, 4 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index ce6a764e905b..cfeb13b5a216 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2071,7 +2071,7 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
 {
         struct p_sizes p;
         sector_t d_size, u_size;
-        int q_order_type;
+        int q_order_type, max_bio_size;
         int ok;
 
         if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
@@ -2079,17 +2079,20 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
                 d_size = drbd_get_max_capacity(mdev->ldev);
                 u_size = mdev->ldev->dc.disk_size;
                 q_order_type = drbd_queue_order_type(mdev);
+                max_bio_size = queue_max_hw_sectors(mdev->ldev->backing_bdev->bd_disk->queue) << 9;
+                max_bio_size = min_t(int, max_bio_size, DRBD_MAX_BIO_SIZE);
                 put_ldev(mdev);
         } else {
                 d_size = 0;
                 u_size = 0;
                 q_order_type = QUEUE_ORDERED_NONE;
+                max_bio_size = DRBD_MAX_BIO_SIZE; /* ... multiple BIOs per peer_request */
         }
 
         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));
-        p.max_bio_size = cpu_to_be32(queue_max_hw_sectors(mdev->rq_queue) << 9);
+        p.max_bio_size = cpu_to_be32(max_bio_size);
         p.queue_order_type = cpu_to_be16(q_order_type);
         p.dds_flags = cpu_to_be16(flags);
 
@@ -3048,6 +3051,8 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
         mdev->agreed_pro_version = PRO_VERSION_MAX;
         mdev->write_ordering = WO_bdev_flush;
         mdev->resync_wenr = LC_FREE;
+        mdev->peer_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
+        mdev->local_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
 }
 
 void drbd_mdev_cleanup(struct drbd_conf *mdev)
@@ -3422,7 +3427,9 @@ struct drbd_conf *drbd_new_device(unsigned int minor)
         q->backing_dev_info.congested_data = mdev;
 
         blk_queue_make_request(q, drbd_make_request);
-        blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE >> 9);
+        /* Setting the max_hw_sectors to an odd value of 8kibyte here
+           This triggers a max_bio_size message upon first attach or connect */
+        blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE_SAFE >> 8);
         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
         blk_queue_merge_bvec(q, drbd_merge_bvec);
         q->queue_lock = &mdev->req_lock;
@@ -3634,7 +3641,8 @@ struct meta_data_on_disk {
               /* `-- act_log->nr_elements <-- sync_conf.al_extents */
         u32 bm_offset;         /* offset to the bitmap, from here */
         u32 bm_bytes_per_bit;  /* BM_BLOCK_SIZE */
-        u32 reserved_u32[4];
+        u32 la_peer_max_bio_size;   /* last peer max_bio_size */
+        u32 reserved_u32[3];
 
 } __packed;
 
@@ -3675,6 +3683,7 @@ void drbd_md_sync(struct drbd_conf *mdev)
         buffer->device_uuid = cpu_to_be64(mdev->ldev->md.device_uuid);
 
         buffer->bm_offset = cpu_to_be32(mdev->ldev->md.bm_offset);
+        buffer->la_peer_max_bio_size = cpu_to_be32(mdev->peer_max_bio_size);
 
         D_ASSERT(drbd_md_ss__(mdev, mdev->ldev) == mdev->ldev->md.md_offset);
         sector = mdev->ldev->md.md_offset;
@@ -3758,6 +3767,15 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
         mdev->sync_conf.al_extents = be32_to_cpu(buffer->al_nr_extents);
         bdev->md.device_uuid = be64_to_cpu(buffer->device_uuid);
 
+        spin_lock_irq(&mdev->req_lock);
+        if (mdev->state.conn < C_CONNECTED) {
+                int peer;
+                peer = be32_to_cpu(buffer->la_peer_max_bio_size);
+                peer = max_t(int, peer, DRBD_MAX_BIO_SIZE_SAFE);
+                mdev->peer_max_bio_size = peer;
+        }
+        spin_unlock_irq(&mdev->req_lock);
+
         if (mdev->sync_conf.al_extents < 7)
                 mdev->sync_conf.al_extents = 127;