14 files changed, 377 insertions, 200 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 7ec14097fef1..cb97174e2366 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -64,6 +64,8 @@ struct btrfs_worker_thread {
         int idle;
 };
 
+static int __btrfs_start_workers(struct btrfs_workers *workers);
+
 /*
  * btrfs_start_workers uses kthread_run, which can block waiting for memory
  * for a very long time.  It will actually throttle on page writeback,
@@ -88,27 +90,10 @@ static void start_new_worker_func(struct btrfs_work *work)
 {
         struct worker_start *start;
         start = container_of(work, struct worker_start, work);
-        btrfs_start_workers(start->queue, 1);
+        __btrfs_start_workers(start->queue);
         kfree(start);
 }
 
-static int start_new_worker(struct btrfs_workers *queue)
-{
-        struct worker_start *start;
-        int ret;
-
-        start = kzalloc(sizeof(*start), GFP_NOFS);
-        if (!start)
-                return -ENOMEM;
-
-        start->work.func = start_new_worker_func;
-        start->queue = queue;
-        ret = btrfs_queue_worker(queue->atomic_worker_start, &start->work);
-        if (ret)
-                kfree(start);
-        return ret;
-}
-
 /*
  * helper function to move a thread onto the idle list after it
  * has finished some requests.
@@ -153,12 +138,20 @@ static void check_busy_worker(struct btrfs_worker_thread *worker)
 static void check_pending_worker_creates(struct btrfs_worker_thread *worker)
 {
         struct btrfs_workers *workers = worker->workers;
+        struct worker_start *start;
         unsigned long flags;
 
         rmb();
         if (!workers->atomic_start_pending)
                 return;
 
+        start = kzalloc(sizeof(*start), GFP_NOFS);
+        if (!start)
+                return;
+
+        start->work.func = start_new_worker_func;
+        start->queue = workers;
+
         spin_lock_irqsave(&workers->lock, flags);
         if (!workers->atomic_start_pending)
                 goto out;
@@ -170,10 +163,11 @@ static void check_pending_worker_creates(struct btrfs_worker_thread *worker)
 
         workers->num_workers_starting += 1;
         spin_unlock_irqrestore(&workers->lock, flags);
-        start_new_worker(workers);
+        btrfs_queue_worker(workers->atomic_worker_start, &start->work);
         return;
 
 out:
+        kfree(start);
         spin_unlock_irqrestore(&workers->lock, flags);
 }
 
@@ -331,7 +325,7 @@ again:
                         run_ordered_completions(worker->workers, work);
 
                         check_pending_worker_creates(worker);
-
+                        cond_resched();
                 }
 
                 spin_lock_irq(&worker->lock);
@@ -462,56 +456,55 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max,
  * starts new worker threads.  This does not enforce the max worker
  * count in case you need to temporarily go past it.
  */
-static int __btrfs_start_workers(struct btrfs_workers *workers,
-                                 int num_workers)
+static int __btrfs_start_workers(struct btrfs_workers *workers)
 {
         struct btrfs_worker_thread *worker;
         int ret = 0;
-        int i;
 
-        for (i = 0; i < num_workers; i++) {
-                worker = kzalloc(sizeof(*worker), GFP_NOFS);
-                if (!worker) {
-                        ret = -ENOMEM;
-                        goto fail;
-                }
+        worker = kzalloc(sizeof(*worker), GFP_NOFS);
+        if (!worker) {
+                ret = -ENOMEM;
+                goto fail;
+        }
 
-                INIT_LIST_HEAD(&worker->pending);
-                INIT_LIST_HEAD(&worker->prio_pending);
-                INIT_LIST_HEAD(&worker->worker_list);
-                spin_lock_init(&worker->lock);
-
-                atomic_set(&worker->num_pending, 0);
-                atomic_set(&worker->refs, 1);
-                worker->workers = workers;
-                worker->task = kthread_run(worker_loop, worker,
-                                           "btrfs-%s-%d", workers->name,
-                                           workers->num_workers + i);
-                if (IS_ERR(worker->task)) {
-                        ret = PTR_ERR(worker->task);
-                        kfree(worker);
-                        goto fail;
-                }
-                spin_lock_irq(&workers->lock);
-                list_add_tail(&worker->worker_list, &workers->idle_list);
-                worker->idle = 1;
-                workers->num_workers++;
-                workers->num_workers_starting--;
-                WARN_ON(workers->num_workers_starting < 0);
-                spin_unlock_irq(&workers->lock);
+        INIT_LIST_HEAD(&worker->pending);
+        INIT_LIST_HEAD(&worker->prio_pending);
+        INIT_LIST_HEAD(&worker->worker_list);
+        spin_lock_init(&worker->lock);
+
+        atomic_set(&worker->num_pending, 0);
+        atomic_set(&worker->refs, 1);
+        worker->workers = workers;
+        worker->task = kthread_run(worker_loop, worker,
+                                   "btrfs-%s-%d", workers->name,
+                                   workers->num_workers + 1);
+        if (IS_ERR(worker->task)) {
+                ret = PTR_ERR(worker->task);
+                kfree(worker);
+                goto fail;
         }
+        spin_lock_irq(&workers->lock);
+        list_add_tail(&worker->worker_list, &workers->idle_list);
+        worker->idle = 1;
+        workers->num_workers++;
+        workers->num_workers_starting--;
+        WARN_ON(workers->num_workers_starting < 0);
+        spin_unlock_irq(&workers->lock);
+
         return 0;
 fail:
-        btrfs_stop_workers(workers);
+        spin_lock_irq(&workers->lock);
+        workers->num_workers_starting--;
+        spin_unlock_irq(&workers->lock);
         return ret;
 }
 
-int btrfs_start_workers(struct btrfs_workers *workers, int num_workers)
+int btrfs_start_workers(struct btrfs_workers *workers)
 {
         spin_lock_irq(&workers->lock);
-        workers->num_workers_starting += num_workers;
+        workers->num_workers_starting++;
         spin_unlock_irq(&workers->lock);
-        return __btrfs_start_workers(workers, num_workers);
+        return __btrfs_start_workers(workers);
 }
 
 /*
@@ -568,6 +561,7 @@ static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers)
         struct btrfs_worker_thread *worker;
         unsigned long flags;
         struct list_head *fallback;
+        int ret;
 
 again:
         spin_lock_irqsave(&workers->lock, flags);
@@ -584,7 +578,9 @@ again:
                         workers->num_workers_starting++;
                         spin_unlock_irqrestore(&workers->lock, flags);
                         /* we're below the limit, start another worker */
-                        __btrfs_start_workers(workers, 1);
+                        ret = __btrfs_start_workers(workers);
+                        if (ret)
+                                goto fallback;
                         goto again;
                 }
         }
@@ -665,7 +661,7 @@ void btrfs_set_work_high_prio(struct btrfs_work *work)
 /*
  * places a struct btrfs_work into the pending queue of one of the kthreads
  */
-int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
+void btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
 {
         struct btrfs_worker_thread *worker;
         unsigned long flags;
@@ -673,7 +669,7 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
 
         /* don't requeue something already on a list */
         if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
-                goto out;
+                return;
 
         worker = find_worker(workers);
         if (workers->ordered) {
@@ -712,7 +708,4 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
         if (wake)
                 wake_up_process(worker->task);
         spin_unlock_irqrestore(&worker->lock, flags);
-
-out:
-        return 0;
 }
diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h
index 5077746cf85e..f34cc31fa3c9 100644
--- a/fs/btrfs/async-thread.h
+++ b/fs/btrfs/async-thread.h
@@ -109,8 +109,8 @@ struct btrfs_workers {
         char *name;
 };
 
-int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work);
-int btrfs_start_workers(struct btrfs_workers *workers, int num_workers);
+void btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work);
+int btrfs_start_workers(struct btrfs_workers *workers);
 int btrfs_stop_workers(struct btrfs_workers *workers);
 void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max,
                         struct btrfs_workers *async_starter);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 50634abef9b4..67385033323d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2692,7 +2692,8 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
 int btrfs_readpage(struct file *file, struct page *page);
 void btrfs_evict_inode(struct inode *inode);
 int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc);
-void btrfs_dirty_inode(struct inode *inode, int flags);
+int btrfs_dirty_inode(struct inode *inode);
+int btrfs_update_time(struct file *file);
 struct inode *btrfs_alloc_inode(struct super_block *sb);
 void btrfs_destroy_inode(struct inode *inode);
 int btrfs_drop_inode(struct inode *inode);
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 5b163572e0ca..9c1eccc2c503 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -640,8 +640,8 @@ static int btrfs_delayed_inode_reserve_metadata(
          * Now if src_rsv == delalloc_block_rsv we'll let it just steal since
          * we're accounted for.
          */
-        if (!trans->bytes_reserved &&
-            src_rsv != &root->fs_info->delalloc_block_rsv) {
+        if (!src_rsv || (!trans->bytes_reserved &&
+            src_rsv != &root->fs_info->delalloc_block_rsv)) {
                 ret = btrfs_block_rsv_add_noflush(root, dst_rsv, num_bytes);
                 /*
                  * Since we're under a transaction reserve_metadata_bytes could
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 632f8f3cc9db..f44b3928dc2d 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2194,19 +2194,27 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         fs_info->endio_meta_write_workers.idle_thresh = 2;
         fs_info->readahead_workers.idle_thresh = 2;
 
-        btrfs_start_workers(&fs_info->workers, 1);
-        btrfs_start_workers(&fs_info->generic_worker, 1);
-        btrfs_start_workers(&fs_info->submit_workers, 1);
-        btrfs_start_workers(&fs_info->delalloc_workers, 1);
-        btrfs_start_workers(&fs_info->fixup_workers, 1);
-        btrfs_start_workers(&fs_info->endio_workers, 1);
-        btrfs_start_workers(&fs_info->endio_meta_workers, 1);
-        btrfs_start_workers(&fs_info->endio_meta_write_workers, 1);
-        btrfs_start_workers(&fs_info->endio_write_workers, 1);
-        btrfs_start_workers(&fs_info->endio_freespace_worker, 1);
-        btrfs_start_workers(&fs_info->delayed_workers, 1);
-        btrfs_start_workers(&fs_info->caching_workers, 1);
-        btrfs_start_workers(&fs_info->readahead_workers, 1);
+        /*
+         * btrfs_start_workers can really only fail because of ENOMEM so just
+         * return -ENOMEM if any of these fail.
+         */
+        ret = btrfs_start_workers(&fs_info->workers);
+        ret |= btrfs_start_workers(&fs_info->generic_worker);
+        ret |= btrfs_start_workers(&fs_info->submit_workers);
+        ret |= btrfs_start_workers(&fs_info->delalloc_workers);
+        ret |= btrfs_start_workers(&fs_info->fixup_workers);
+        ret |= btrfs_start_workers(&fs_info->endio_workers);
+        ret |= btrfs_start_workers(&fs_info->endio_meta_workers);
+        ret |= btrfs_start_workers(&fs_info->endio_meta_write_workers);
+        ret |= btrfs_start_workers(&fs_info->endio_write_workers);
+        ret |= btrfs_start_workers(&fs_info->endio_freespace_worker);
+        ret |= btrfs_start_workers(&fs_info->delayed_workers);
+        ret |= btrfs_start_workers(&fs_info->caching_workers);
+        ret |= btrfs_start_workers(&fs_info->readahead_workers);
+        if (ret) {
+                ret = -ENOMEM;
+                goto fail_sb_buffer;
+        }
 
         fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
         fs_info->bdi.ra_pages = max(fs_info->bdi.ra_pages,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index f0d5718d2587..f5fbe576d2ba 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2822,7 +2822,7 @@ out_free:
         btrfs_release_path(path);
 out:
         spin_lock(&block_group->lock);
-        if (!ret)
+        if (!ret && dcs == BTRFS_DC_SETUP)
                 block_group->cache_generation = trans->transid;
         block_group->disk_cache_state = dcs;
         spin_unlock(&block_group->lock);
@@ -4204,12 +4204,17 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_block_rsv *block_rsv = &root->fs_info->delalloc_block_rsv;
         u64 to_reserve = 0;
+        u64 csum_bytes;
         unsigned nr_extents = 0;
+        int extra_reserve = 0;
         int flush = 1;
         int ret;
 
+        /* Need to be holding the i_mutex here if we aren't free space cache */
         if (btrfs_is_free_space_inode(root, inode))
                 flush = 0;
+        else
+                WARN_ON(!mutex_is_locked(&inode->i_mutex));
 
         if (flush && btrfs_transaction_in_commit(root->fs_info))
                 schedule_timeout(1);
@@ -4220,11 +4225,9 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
         BTRFS_I(inode)->outstanding_extents++;
 
         if (BTRFS_I(inode)->outstanding_extents >
-            BTRFS_I(inode)->reserved_extents) {
+            BTRFS_I(inode)->reserved_extents)
                 nr_extents = BTRFS_I(inode)->outstanding_extents -
                         BTRFS_I(inode)->reserved_extents;
-                BTRFS_I(inode)->reserved_extents += nr_extents;
-        }
 
         /*
          * Add an item to reserve for updating the inode when we complete the
@@ -4232,11 +4235,12 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
          */
         if (!BTRFS_I(inode)->delalloc_meta_reserved) {
                 nr_extents++;
-                BTRFS_I(inode)->delalloc_meta_reserved = 1;
+                extra_reserve = 1;
         }
 
         to_reserve = btrfs_calc_trans_metadata_size(root, nr_extents);
         to_reserve += calc_csum_metadata_size(inode, num_bytes, 1);
+        csum_bytes = BTRFS_I(inode)->csum_bytes;
         spin_unlock(&BTRFS_I(inode)->lock);
 
         ret = reserve_metadata_bytes(root, block_rsv, to_reserve, flush);
@@ -4246,22 +4250,35 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
 
                 spin_lock(&BTRFS_I(inode)->lock);
                 dropped = drop_outstanding_extent(inode);
-                to_free = calc_csum_metadata_size(inode, num_bytes, 0);
-                spin_unlock(&BTRFS_I(inode)->lock);
-                to_free += btrfs_calc_trans_metadata_size(root, dropped);
-
                 /*
-                 * Somebody could have come in and twiddled with the
-                 * reservation, so if we have to free more than we would have
-                 * reserved from this reservation go ahead and release those
-                 * bytes.
+                 * If the inodes csum_bytes is the same as the original
+                 * csum_bytes then we know we haven't raced with any free()ers
+                 * so we can just reduce our inodes csum bytes and carry on.
+                 * Otherwise we have to do the normal free thing to account for
+                 * the case that the free side didn't free up its reserve
+                 * because of this outstanding reservation.
                  */
-                to_free -= to_reserve;
+                if (BTRFS_I(inode)->csum_bytes == csum_bytes)
+                        calc_csum_metadata_size(inode, num_bytes, 0);
+                else
+                        to_free = calc_csum_metadata_size(inode, num_bytes, 0);
+                spin_unlock(&BTRFS_I(inode)->lock);
+                if (dropped)
+                        to_free += btrfs_calc_trans_metadata_size(root, dropped);
+
                 if (to_free)
                         btrfs_block_rsv_release(root, block_rsv, to_free);
                 return ret;
         }
 
+        spin_lock(&BTRFS_I(inode)->lock);
+        if (extra_reserve) {
+                BTRFS_I(inode)->delalloc_meta_reserved = 1;
+                nr_extents--;
+        }
+        BTRFS_I(inode)->reserved_extents += nr_extents;
+        spin_unlock(&BTRFS_I(inode)->lock);
+
         block_rsv_add_bytes(block_rsv, to_reserve, 1);
 
         return 0;
@@ -5107,11 +5124,11 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
         struct btrfs_root *root = orig_root->fs_info->extent_root;
         struct btrfs_free_cluster *last_ptr = NULL;
         struct btrfs_block_group_cache *block_group = NULL;
+        struct btrfs_block_group_cache *used_block_group;
         int empty_cluster = 2 * 1024 * 1024;
         int allowed_chunk_alloc = 0;
         int done_chunk_alloc = 0;
         struct btrfs_space_info *space_info;
-        int last_ptr_loop = 0;
         int loop = 0;
         int index = 0;
         int alloc_type = (data & BTRFS_BLOCK_GROUP_DATA) ?
@@ -5173,6 +5190,7 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
 ideal_cache:
                 block_group = btrfs_lookup_block_group(root->fs_info,
                                                        search_start);
+                used_block_group = block_group;
                 /*
                  * we don't want to use the block group if it doesn't match our
                  * allocation bits, or if its not cached.
@@ -5210,6 +5228,7 @@ search:
                 u64 offset;
                 int cached;
 
+                used_block_group = block_group;
                 btrfs_get_block_group(block_group);
                 search_start = block_group->key.objectid;
 
@@ -5286,71 +5305,62 @@ alloc:
                 spin_unlock(&block_group->free_space_ctl->tree_lock);
 
                 /*
-                 * Ok we want to try and use the cluster allocator, so lets look
-                 * there, unless we are on LOOP_NO_EMPTY_SIZE, since we will
-                 * have tried the cluster allocator plenty of times at this
-                 * point and not have found anything, so we are likely way too
-                 * fragmented for the clustering stuff to find anything, so lets
-                 * just skip it and let the allocator find whatever block it can
-                 * find
+                 * Ok we want to try and use the cluster allocator, so
+                 * lets look there
                  */
-                if (last_ptr && loop < LOOP_NO_EMPTY_SIZE) {
+                if (last_ptr) {
                         /*
                          * the refill lock keeps out other
                          * people trying to start a new cluster
                          */
                         spin_lock(&last_ptr->refill_lock);
-                        if (!last_ptr->block_group ||
-                            last_ptr->block_group->ro ||
-                            !block_group_bits(last_ptr->block_group, data))
+                        used_block_group = last_ptr->block_group;
+                        if (used_block_group != block_group &&
+                            (!used_block_group ||
+                             used_block_group->ro ||
+                             !block_group_bits(used_block_group, data))) {
+                                used_block_group = block_group;
                                 goto refill_cluster;
+                        }
+
+                        if (used_block_group != block_group)
+                                btrfs_get_block_group(used_block_group);
 
-                        offset = btrfs_alloc_from_cluster(block_group, last_ptr,
-                                                 num_bytes, search_start);
+                        offset = btrfs_alloc_from_cluster(used_block_group,
+                          last_ptr, num_bytes, used_block_group->key.objectid);
                         if (offset) {
                                 /* we have a block, we're done */
                                 spin_unlock(&last_ptr->refill_lock);
                                 goto checks;
                         }
 
-                        spin_lock(&last_ptr->lock);
-                        /*
-                         * whoops, this cluster doesn't actually point to
-                         * this block group.  Get a ref on the block
-                         * group is does point to and try again
-                         */
-                        if (!last_ptr_loop && last_ptr->block_group &&
-                            last_ptr->block_group != block_group &&
-                            index <=
-                                 get_block_group_index(last_ptr->block_group)) {
-
-                                btrfs_put_block_group(block_group);
-                                block_group = last_ptr->block_group;
-                                btrfs_get_block_group(block_group);
-                                spin_unlock(&last_ptr->lock);
-                                spin_unlock(&last_ptr->refill_lock);
-
-                                last_ptr_loop = 1;
-                                search_start = block_group->key.objectid;
-                                /*
-                                 * we know this block group is properly
-                                 * in the list because
-                                 * btrfs_remove_block_group, drops the
-                                 * cluster before it removes the block
-                                 * group from the list
-                                 */
-                                goto have_block_group;
+                        WARN_ON(last_ptr->block_group != used_block_group);
+                        if (used_block_group != block_group) {
+                                btrfs_put_block_group(used_block_group);
+                                used_block_group = block_group;
                         }
-                        spin_unlock(&last_ptr->lock);
 refill_cluster:
+                        BUG_ON(used_block_group != block_group);
+                        /* If we are on LOOP_NO_EMPTY_SIZE, we can't
+                         * set up a new clusters, so lets just skip it
+                         * and let the allocator find whatever block
+                         * it can find.  If we reach this point, we
+                         * will have tried the cluster allocator
+                         * plenty of times and not have found
+                         * anything, so we are likely way too
+                         * fragmented for the clustering stuff to find
+                         * anything.  */
+                        if (loop >= LOOP_NO_EMPTY_SIZE) {
+                                spin_unlock(&last_ptr->refill_lock);
+                                goto unclustered_alloc;
+                        }
+
                         /*
                          * this cluster didn't work out, free it and
                          * start over
                          */
                         btrfs_return_cluster_to_free_space(NULL, last_ptr);
 
-                        last_ptr_loop = 0;
-
                         /* allocate a cluster in this block group */
                         ret = btrfs_find_space_cluster(trans, root,
                                                block_group, last_ptr,
@@ -5390,6 +5400,7 @@ refill_cluster:
                         goto loop;
                 }
 
+unclustered_alloc:
                 offset = btrfs_find_space_for_alloc(block_group, search_start,
                                                     num_bytes, empty_size);
                 /*
@@ -5416,14 +5427,14 @@ checks:
                 search_start = stripe_align(root, offset);
                 /* move on to the next group */
                 if (search_start + num_bytes >= search_end) {
-                        btrfs_add_free_space(block_group, offset, num_bytes);
+                        btrfs_add_free_space(used_block_group, offset, num_bytes);
                         goto loop;
                 }
 
                 /* move on to the next group */
                 if (search_start + num_bytes >
-                    block_group->key.objectid + block_group->key.offset) {
-                        btrfs_add_free_space(block_group, offset, num_bytes);
+                    used_block_group->key.objectid + used_block_group->key.offset) {
+                        btrfs_add_free_space(used_block_group, offset, num_bytes);
                         goto loop;
                 }
 
@@ -5431,14 +5442,14 @@ checks:
                 ins->offset = num_bytes;
 
                 if (offset < search_start)
-                        btrfs_add_free_space(block_group, offset,
+                        btrfs_add_free_space(used_block_group, offset,
                                              search_start - offset);
                 BUG_ON(offset > search_start);
 
-                ret = btrfs_update_reserved_bytes(block_group, num_bytes,
+                ret = btrfs_update_reserved_bytes(used_block_group, num_bytes,
                                                   alloc_type);
                 if (ret == -EAGAIN) {
-                        btrfs_add_free_space(block_group, offset, num_bytes);
+                        btrfs_add_free_space(used_block_group, offset, num_bytes);
                         goto loop;
                 }
 
@@ -5447,15 +5458,19 @@ checks:
                 ins->offset = num_bytes;
 
                 if (offset < search_start)
-                        btrfs_add_free_space(block_group, offset,
+                        btrfs_add_free_space(used_block_group, offset,
                                              search_start - offset);
                 BUG_ON(offset > search_start);
+                if (used_block_group != block_group)
+                        btrfs_put_block_group(used_block_group);
                 btrfs_put_block_group(block_group);
                 break;
 loop:
                 failed_cluster_refill = false;
                 failed_alloc = false;
                 BUG_ON(index != get_block_group_index(block_group));
+                if (used_block_group != block_group)
+                        btrfs_put_block_group(used_block_group);
                 btrfs_put_block_group(block_group);
         }
         up_read(&space_info->groups_sem);
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index be1bf627a14b..49f3c9dc09f4 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -935,8 +935,10 @@ again:
         node = tree_search(tree, start);
         if (!node) {
                 prealloc = alloc_extent_state_atomic(prealloc);
-                if (!prealloc)
-                        return -ENOMEM;
+                if (!prealloc) {
+                        err = -ENOMEM;
+                        goto out;
+                }
                 err = insert_state(tree, prealloc, start, end, &bits);
                 prealloc = NULL;
                 BUG_ON(err == -EEXIST);
@@ -992,8 +994,10 @@ hit_next:
          */
         if (state->start < start) {
                 prealloc = alloc_extent_state_atomic(prealloc);
-                if (!prealloc)
-                        return -ENOMEM;
+                if (!prealloc) {
+                        err = -ENOMEM;
+                        goto out;
+                }
                 err = split_state(tree, state, prealloc, start);
                 BUG_ON(err == -EEXIST);
                 prealloc = NULL;
@@ -1024,8 +1028,10 @@ hit_next:
                         this_end = last_start - 1;
 
                 prealloc = alloc_extent_state_atomic(prealloc);
-                if (!prealloc)
-                        return -ENOMEM;
+                if (!prealloc) {
+                        err = -ENOMEM;
+                        goto out;
+                }
 
                 /*
                  * Avoid to free 'prealloc' if it can be merged with
@@ -1051,8 +1057,10 @@ hit_next:
          */
         if (state->start <= end && state->end > end) {
                 prealloc = alloc_extent_state_atomic(prealloc);
-                if (!prealloc)
-                        return -ENOMEM;
+                if (!prealloc) {
+                        err = -ENOMEM;
+                        goto out;
+                }
 
                 err = split_state(tree, state, prealloc, end + 1);
                 BUG_ON(err == -EEXIST);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index dafdfa059bf6..97fbe939c050 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1167,6 +1167,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
         nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
                      (sizeof(struct page *)));
+        nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
+        nrptrs = max(nrptrs, 8);
         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
         if (!pages)
                 return -ENOMEM;
@@ -1387,7 +1389,11 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                 goto out;
         }
 
-        file_update_time(file);
+        err = btrfs_update_time(file);
+        if (err) {
+                mutex_unlock(&inode->i_mutex);
+                goto out;
+        }
         BTRFS_I(inode)->sequence++;
 
         start_pos = round_down(pos, root->sectorsize);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2c984f7d4c2a..0a6b928813a4 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -38,6 +38,7 @@
 #include <linux/falloc.h>
 #include <linux/slab.h>
 #include <linux/ratelimit.h>
+#include <linux/mount.h>
 #include "compat.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -2031,7 +2032,7 @@ int btrfs_orphan_add(struct btrfs_trans_handle *trans, struct inode *inode)
         /* insert an orphan item to track this unlinked/truncated file */
         if (insert >= 1) {
                 ret = btrfs_insert_orphan_item(trans, root, btrfs_ino(inode));
-                BUG_ON(ret);
+                BUG_ON(ret && ret != -EEXIST);
         }
 
         /* insert an orphan item to track subvolume contains orphan files */
@@ -2158,6 +2159,38 @@ int btrfs_orphan_cleanup(struct btrfs_root *root)
                 if (ret && ret != -ESTALE)
                         goto out;
 
+                if (ret == -ESTALE && root == root->fs_info->tree_root) {
+                        struct btrfs_root *dead_root;
+                        struct btrfs_fs_info *fs_info = root->fs_info;
+                        int is_dead_root = 0;
+
+                        /*
+                         * this is an orphan in the tree root. Currently these
+                         * could come from 2 sources:
+                         *  a) a snapshot deletion in progress
+                         *  b) a free space cache inode
+                         * We need to distinguish those two, as the snapshot
+                         * orphan must not get deleted.
+                         * find_dead_roots already ran before us, so if this
+                         * is a snapshot deletion, we should find the root
+                         * in the dead_roots list
+                         */
+                        spin_lock(&fs_info->trans_lock);
+                        list_for_each_entry(dead_root, &fs_info->dead_roots,
+                                            root_list) {
+                                if (dead_root->root_key.objectid ==
+                                    found_key.objectid) {
+                                        is_dead_root = 1;
+                                        break;
+                                }
+                        }
+                        spin_unlock(&fs_info->trans_lock);
+                        if (is_dead_root) {
+                                /* prevent this orphan from being found again */
+                                key.offset = found_key.objectid - 1;
+                                continue;
+                        }
+                }
                 /*
                  * Inode is already gone but the orphan item is still there,
                  * kill the orphan item.
@@ -2191,7 +2224,14 @@ int btrfs_orphan_cleanup(struct btrfs_root *root)
                                 continue;
                         }
                         nr_truncate++;
+                        /*
+                         * Need to hold the imutex for reservation purposes, not
+                         * a huge deal here but I have a WARN_ON in
+                         * btrfs_delalloc_reserve_space to catch offenders.
+                         */
+                        mutex_lock(&inode->i_mutex);
                         ret = btrfs_truncate(inode);
+                        mutex_unlock(&inode->i_mutex);
                 } else {
                         nr_unlink++;
                 }
@@ -3327,7 +3367,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
                         u64 hint_byte = 0;
                         hole_size = last_byte - cur_offset;
 
-                        trans = btrfs_start_transaction(root, 2);
+                        trans = btrfs_start_transaction(root, 3);
                         if (IS_ERR(trans)) {
                                 err = PTR_ERR(trans);
                                 break;
@@ -3337,6 +3377,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
                                                  cur_offset + hole_size,
                                                  &hint_byte, 1);
                         if (err) {
+                                btrfs_update_inode(trans, root, inode);
                                 btrfs_end_transaction(trans, root);
                                 break;
                         }
@@ -3346,6 +3387,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
                                         0, hole_size, 0, hole_size,
                                         0, 0, 0);
                         if (err) {
+                                btrfs_update_inode(trans, root, inode);
                                 btrfs_end_transaction(trans, root);
                                 break;
                         }
@@ -3353,6 +3395,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
                         btrfs_drop_extent_cache(inode, hole_start,
                                         last_byte - 1, 0);
 
+                        btrfs_update_inode(trans, root, inode);
                         btrfs_end_transaction(trans, root);
                 }
                 free_extent_map(em);
@@ -3370,6 +3413,8 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
 
 static int btrfs_setsize(struct inode *inode, loff_t newsize)
 {
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct btrfs_trans_handle *trans;
         loff_t oldsize = i_size_read(inode);
         int ret;
 
@@ -3377,16 +3422,19 @@ static int btrfs_setsize(struct inode *inode, loff_t newsize)
                 return 0;
 
         if (newsize > oldsize) {
-                i_size_write(inode, newsize);
-                btrfs_ordered_update_i_size(inode, i_size_read(inode), NULL);
                 truncate_pagecache(inode, oldsize, newsize);
                 ret = btrfs_cont_expand(inode, oldsize, newsize);
-                if (ret) {
-                        btrfs_setsize(inode, oldsize);
+                if (ret)
                         return ret;
-                }
 
-                mark_inode_dirty(inode);
+                trans = btrfs_start_transaction(root, 1);
+                if (IS_ERR(trans))
+                        return PTR_ERR(trans);
+
+                i_size_write(inode, newsize);
+                btrfs_ordered_update_i_size(inode, i_size_read(inode), NULL);
+                ret = btrfs_update_inode(trans, root, inode);
+                btrfs_end_transaction_throttle(trans, root);
         } else {
 
                 /*
@@ -3426,9 +3474,9 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
 
         if (attr->ia_valid) {
                 setattr_copy(inode, attr);
-                mark_inode_dirty(inode);
+                err = btrfs_dirty_inode(inode);
 
-                if (attr->ia_valid & ATTR_MODE)
+                if (!err && attr->ia_valid & ATTR_MODE)
                         err = btrfs_acl_chmod(inode);
         }
 
@@ -4204,42 +4252,80 @@ int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc)
  * FIXME, needs more benchmarking...there are no reasons other than performance
  * to keep or drop this code.
  */
-void btrfs_dirty_inode(struct inode *inode, int flags)
+int btrfs_dirty_inode(struct inode *inode)
 {
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_trans_handle *trans;
         int ret;
 
         if (BTRFS_I(inode)->dummy_inode)
-                return;
+                return 0;
 
         trans = btrfs_join_transaction(root);
-        BUG_ON(IS_ERR(trans));
+        if (IS_ERR(trans))
+                return PTR_ERR(trans);
 
         ret = btrfs_update_inode(trans, root, inode);
         if (ret && ret == -ENOSPC) {
                 /* whoops, lets try again with the full transaction */
                 btrfs_end_transaction(trans, root);
                 trans = btrfs_start_transaction(root, 1);
-                if (IS_ERR(trans)) {
-                        printk_ratelimited(KERN_ERR "btrfs: fail to "
-                                       "dirty  inode %llu error %ld\n",
-                                       (unsigned long long)btrfs_ino(inode),
-                                       PTR_ERR(trans));
-                        return;
-                }
+                if (IS_ERR(trans))
+                        return PTR_ERR(trans);
 
                 ret = btrfs_update_inode(trans, root, inode);
-                if (ret) {
-                        printk_ratelimited(KERN_ERR "btrfs: fail to "
-                                       "dirty  inode %llu error %d\n",
-                                       (unsigned long long)btrfs_ino(inode),
-                                       ret);
-                }
         }
         btrfs_end_transaction(trans, root);
         if (BTRFS_I(inode)->delayed_node)
                 btrfs_balance_delayed_items(root);
+
+        return ret;
+}
+
+/*
+ * This is a copy of file_update_time.  We need this so we can return error on
+ * ENOSPC for updating the inode in the case of file write and mmap writes.
+ */
+int btrfs_update_time(struct file *file)
+{
+        struct inode *inode = file->f_path.dentry->d_inode;
+        struct timespec now;
+        int ret;
+        enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
+
+        /* First try to exhaust all avenues to not sync */
+        if (IS_NOCMTIME(inode))
+                return 0;
+
+        now = current_fs_time(inode->i_sb);
+        if (!timespec_equal(&inode->i_mtime, &now))
+                sync_it = S_MTIME;
+
+        if (!timespec_equal(&inode->i_ctime, &now))
+                sync_it |= S_CTIME;
+
+        if (IS_I_VERSION(inode))
+                sync_it |= S_VERSION;
+
+        if (!sync_it)
+                return 0;
+
+        /* Finally allowed to write? Takes lock. */
+        if (mnt_want_write_file(file))
+                return 0;
+
+        /* Only change inode inside the lock region */
+        if (sync_it & S_VERSION)
+                inode_inc_iversion(inode);
+        if (sync_it & S_CTIME)
+                inode->i_ctime = now;
+        if (sync_it & S_MTIME)
+                inode->i_mtime = now;
+        ret = btrfs_dirty_inode(inode);
+        if (!ret)
+                mark_inode_dirty_sync(inode);
+        mnt_drop_write(file->f_path.mnt);
+        return ret;
 }
 
 /*
@@ -4555,11 +4641,18 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
                 goto out_unlock;
         }
 
+        /*
+        * If the active LSM wants to access the inode during
+        * d_instantiate it needs these. Smack checks to see
+        * if the filesystem supports xattrs by looking at the
+        * ops vector.
+        */
+
+        inode->i_op = &btrfs_special_inode_operations;
         err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index);
         if (err)
                 drop_inode = 1;
         else {
-                inode->i_op = &btrfs_special_inode_operations;
                 init_special_inode(inode, inode->i_mode, rdev);
                 btrfs_update_inode(trans, root, inode);
         }
@@ -4613,14 +4706,21 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
                 goto out_unlock;
         }
 
+        /*
+        * If the active LSM wants to access the inode during
+        * d_instantiate it needs these. Smack checks to see
+        * if the filesystem supports xattrs by looking at the
+        * ops vector.
+        */
+        inode->i_fop = &btrfs_file_operations;
+        inode->i_op = &btrfs_file_inode_operations;
+
         err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index);
         if (err)
                 drop_inode = 1;
         else {
                 inode->i_mapping->a_ops = &btrfs_aops;
                 inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
-                inode->i_fop = &btrfs_file_operations;
-                inode->i_op = &btrfs_file_inode_operations;
                 BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
         }
 out_unlock:
@@ -6303,7 +6403,12 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
         u64 page_start;
         u64 page_end;
 
+        /* Need this to keep space reservations serialized */
+        mutex_lock(&inode->i_mutex);
         ret  = btrfs_delalloc_reserve_space(inode, PAGE_CACHE_SIZE);
+        mutex_unlock(&inode->i_mutex);
+        if (!ret)
+                ret = btrfs_update_time(vma->vm_file);
         if (ret) {
                 if (ret == -ENOMEM)
                         ret = VM_FAULT_OOM;
@@ -6515,8 +6620,9 @@ static int btrfs_truncate(struct inode *inode)
                         /* Just need the 1 for updating the inode */
                         trans = btrfs_start_transaction(root, 1);
                         if (IS_ERR(trans)) {
-                                err = PTR_ERR(trans);
-                                goto out;
+                                ret = err = PTR_ERR(trans);
+                                trans = NULL;
+                                break;
                         }
                 }
 
@@ -7076,14 +7182,21 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
                 goto out_unlock;
         }
 
+        /*
+        * If the active LSM wants to access the inode during
+        * d_instantiate it needs these. Smack checks to see
+        * if the filesystem supports xattrs by looking at the
+        * ops vector.
+        */
+        inode->i_fop = &btrfs_file_operations;
+        inode->i_op = &btrfs_file_inode_operations;
+
         err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index);
         if (err)
                 drop_inode = 1;
         else {
                 inode->i_mapping->a_ops = &btrfs_aops;
                 inode->i_mapping->backing_dev_info = &root->fs_info->bdi;
-                inode->i_fop = &btrfs_file_operations;
-                inode->i_op = &btrfs_file_inode_operations;
                 BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
         }
         if (drop_inode)
@@ -7353,6 +7466,7 @@ static const struct inode_operations btrfs_symlink_inode_operations = {
         .follow_link    = page_follow_link_light,
         .put_link       = page_put_link,
         .getattr        = btrfs_getattr,
+        .setattr        = btrfs_setattr,
         .permission     = btrfs_permission,
         .setxattr       = btrfs_setxattr,
         .getxattr       = btrfs_getxattr,
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 72d461656f60..c04f02c7d5bb 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -252,11 +252,11 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
         trans = btrfs_join_transaction(root);
         BUG_ON(IS_ERR(trans));
 
+        btrfs_update_iflags(inode);
+        inode->i_ctime = CURRENT_TIME;
         ret = btrfs_update_inode(trans, root, inode);
         BUG_ON(ret);
 
-        btrfs_update_iflags(inode);
-        inode->i_ctime = CURRENT_TIME;
         btrfs_end_transaction(trans, root);
 
         mnt_drop_write(file->f_path.mnt);
@@ -858,8 +858,10 @@ static int cluster_pages_for_defrag(struct inode *inode,
                 return 0;
         file_end = (isize - 1) >> PAGE_CACHE_SHIFT;
 
+        mutex_lock(&inode->i_mutex);
         ret = btrfs_delalloc_reserve_space(inode,
                                            num_pages << PAGE_CACHE_SHIFT);
+        mutex_unlock(&inode->i_mutex);
         if (ret)
                 return ret;
 again:
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index dff29d5e151a..cfb55434a469 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2947,7 +2947,9 @@ static int relocate_file_extent_cluster(struct inode *inode,
         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
         while (index <= last_index) {
+                mutex_lock(&inode->i_mutex);
                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
+                mutex_unlock(&inode->i_mutex);
                 if (ret)
                         goto out;
 
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index c27bcb67f330..ddf2c90d3fc0 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1535,18 +1535,22 @@ static noinline_for_stack int scrub_supers(struct scrub_dev *sdev)
 static noinline_for_stack int scrub_workers_get(struct btrfs_root *root)
 {
         struct btrfs_fs_info *fs_info = root->fs_info;
+        int ret = 0;
 
         mutex_lock(&fs_info->scrub_lock);
         if (fs_info->scrub_workers_refcnt == 0) {
                 btrfs_init_workers(&fs_info->scrub_workers, "scrub",
                            fs_info->thread_pool_size, &fs_info->generic_worker);
                 fs_info->scrub_workers.idle_thresh = 4;
-                btrfs_start_workers(&fs_info->scrub_workers, 1);
+                ret = btrfs_start_workers(&fs_info->scrub_workers);
+                if (ret)
+                        goto out;
         }
         ++fs_info->scrub_workers_refcnt;
+out:
         mutex_unlock(&fs_info->scrub_lock);
 
-        return 0;
+        return ret;
 }
 
 static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index e28ad4baf483..200f63bc6675 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -41,6 +41,7 @@
 #include <linux/slab.h>
 #include <linux/cleancache.h>
 #include <linux/mnt_namespace.h>
+#include <linux/ratelimit.h>
 #include "compat.h"
 #include "delayed-inode.h"
 #include "ctree.h"
@@ -1053,7 +1054,7 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
         u64 avail_space;
         u64 used_space;
         u64 min_stripe_size;
-        int min_stripes = 1;
+        int min_stripes = 1, num_stripes = 1;
         int i = 0, nr_devices;
         int ret;
 
@@ -1067,12 +1068,16 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
 
         /* calc min stripe number for data space alloction */
         type = btrfs_get_alloc_profile(root, 1);
-        if (type & BTRFS_BLOCK_GROUP_RAID0)
+        if (type & BTRFS_BLOCK_GROUP_RAID0) {
                 min_stripes = 2;
-        else if (type & BTRFS_BLOCK_GROUP_RAID1)
+                num_stripes = nr_devices;
+        } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
                 min_stripes = 2;
-        else if (type & BTRFS_BLOCK_GROUP_RAID10)
+                num_stripes = 2;
+        } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
                 min_stripes = 4;
+                num_stripes = 4;
+        }
 
         if (type & BTRFS_BLOCK_GROUP_DUP)
                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
@@ -1141,13 +1146,16 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
         i = nr_devices - 1;
         avail_space = 0;
         while (nr_devices >= min_stripes) {
+                if (num_stripes > nr_devices)
+                        num_stripes = nr_devices;
+
                 if (devices_info[i].max_avail >= min_stripe_size) {
                         int j;
                         u64 alloc_size;
 
-                        avail_space += devices_info[i].max_avail * min_stripes;
+                        avail_space += devices_info[i].max_avail * num_stripes;
                         alloc_size = devices_info[i].max_avail;
-                        for (j = i + 1 - min_stripes; j <= i; j++)
+                        for (j = i + 1 - num_stripes; j <= i; j++)
                                 devices_info[j].max_avail -= alloc_size;
                 }
                 i--;
@@ -1264,6 +1272,16 @@ static int btrfs_unfreeze(struct super_block *sb)
         return 0;
 }
 
+static void btrfs_fs_dirty_inode(struct inode *inode, int flags)
+{
+        int ret;
+
+        ret = btrfs_dirty_inode(inode);
+        if (ret)
+                printk_ratelimited(KERN_ERR "btrfs: fail to dirty inode %Lu "
+                                   "error %d\n", btrfs_ino(inode), ret);
+}
+
 static const struct super_operations btrfs_super_ops = {
         .drop_inode     = btrfs_drop_inode,
         .evict_inode    = btrfs_evict_inode,
@@ -1271,7 +1289,7 @@ static const struct super_operations btrfs_super_ops = {
         .sync_fs        = btrfs_sync_fs,
         .show_options   = btrfs_show_options,
         .write_inode    = btrfs_write_inode,
-        .dirty_inode    = btrfs_dirty_inode,
+        .dirty_inode    = btrfs_fs_dirty_inode,
         .alloc_inode    = btrfs_alloc_inode,
         .destroy_inode  = btrfs_destroy_inode,
         .statfs         = btrfs_statfs,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c37433d3cd82..f4b839fd3c9d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -295,6 +295,12 @@ loop_lock:
                         btrfs_requeue_work(&device->work);
                         goto done;
                 }
+                /* unplug every 64 requests just for good measure */
+                if (batch_run % 64 == 0) {
+                        blk_finish_plug(&plug);
+                        blk_start_plug(&plug);
+                        sync_pending = 0;
+                }
         }
 
         cond_resched();
@@ -1611,7 +1617,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
                 return -EINVAL;
 
-        bdev = blkdev_get_by_path(device_path, FMODE_EXCL,
+        bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
                                   root->fs_info->bdev_holder);
         if (IS_ERR(bdev))
                 return PTR_ERR(bdev);
@@ -3258,7 +3264,7 @@ static void btrfs_end_bio(struct bio *bio, int err)
                  */
                 if (atomic_read(&bbio->error) > bbio->max_errors) {
                         err = -EIO;
-                } else if (err) {
+                } else {
                         /*
                          * this bio is actually up to date, we didn't
                          * go over the max number of errors