1 files changed, 6 insertions, 31 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b8708f994e67..88b969aeeb71 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -227,9 +227,8 @@ loop_lock:
                 cur = pending;
                 pending = pending->bi_next;
                 cur->bi_next = NULL;
-                atomic_dec(&fs_info->nr_async_bios);
 
-                if (atomic_read(&fs_info->nr_async_bios) < limit &&
+                if (atomic_dec_return(&fs_info->nr_async_bios) < limit &&
                     waitqueue_active(&fs_info->async_submit_wait))
                         wake_up(&fs_info->async_submit_wait);
 
@@ -569,9 +568,11 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                 memcpy(new_device, device, sizeof(*new_device));
 
                 /* Safe because we are under uuid_mutex */
-                name = rcu_string_strdup(device->name->str, GFP_NOFS);
-                BUG_ON(device->name && !name); /* -ENOMEM */
-                rcu_assign_pointer(new_device->name, name);
+                if (device->name) {
+                        name = rcu_string_strdup(device->name->str, GFP_NOFS);
+                        BUG_ON(device->name && !name); /* -ENOMEM */
+                        rcu_assign_pointer(new_device->name, name);
+                }
                 new_device->bdev = NULL;
                 new_device->writeable = 0;
                 new_device->in_fs_metadata = 0;
@@ -1744,10 +1745,6 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 
         device->fs_devices = root->fs_info->fs_devices;
 
-        /*
-         * we don't want write_supers to jump in here with our device
-         * half setup
-         */
         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
         list_add_rcu(&device->dev_list, &root->fs_info->fs_devices->devices);
         list_add(&device->dev_alloc_list,
@@ -4609,28 +4606,6 @@ int btrfs_read_sys_array(struct btrfs_root *root)
         return ret;
 }
 
-struct btrfs_device *btrfs_find_device_for_logical(struct btrfs_root *root,
-                                                   u64 logical, int mirror_num)
-{
-        struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
-        int ret;
-        u64 map_length = 0;
-        struct btrfs_bio *bbio = NULL;
-        struct btrfs_device *device;
-
-        BUG_ON(mirror_num == 0);
-        ret = btrfs_map_block(map_tree, WRITE, logical, &map_length, &bbio,
-                              mirror_num);
-        if (ret) {
-                BUG_ON(bbio != NULL);
-                return NULL;
-        }
-        BUG_ON(mirror_num != bbio->mirror_num);
-        device = bbio->stripes[mirror_num - 1].dev;
-        kfree(bbio);
-        return device;
-}
-
 int btrfs_read_chunk_tree(struct btrfs_root *root)
 {
         struct btrfs_path *path;