btrfs: fix lock dep warning, move scratch dev out of device_list_mutex and uuid_mutex

[cascardo/linux.git] / fs / btrfs / volumes.c

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index bd0f45f..7bd553d 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2024,10 +2024,9 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 
        btrfs_sysfs_rm_device_link(fs_info->fs_devices, tgtdev);
 
-       if (tgtdev->bdev) {
-               btrfs_scratch_superblocks(tgtdev->bdev, tgtdev->name->str);
+       if (tgtdev->bdev)
                fs_info->fs_devices->open_devices--;
-       }
+
        fs_info->fs_devices->num_devices--;
 
        next_device = list_entry(fs_info->fs_devices->devices.next,
@@ -2038,10 +2037,18 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
                fs_info->fs_devices->latest_bdev = next_device->bdev;
        list_del_rcu(&tgtdev->dev_list);
 
-       call_rcu(&tgtdev->rcu, free_device);
-
        mutex_unlock(&fs_info->fs_devices->device_list_mutex);
        mutex_unlock(&uuid_mutex);
+
+       /*
+        * The update_dev_time() with in btrfs_scratch_superblocks()
+        * may lead to a call to btrfs_show_devname() which will try
+        * to hold device_list_mutex. And here this device
+        * is already out of device list, so we don't have to hold
+        * the device_list_mutex lock.
+        */
+       btrfs_scratch_superblocks(tgtdev->bdev, tgtdev->name->str);
+       call_rcu(&tgtdev->rcu, free_device);
 }
 
 static int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
@@ -3402,6 +3409,7 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
        u32 count_meta = 0;
        u32 count_sys = 0;
        int chunk_reserved = 0;
+       u64 bytes_used = 0;
 
        /* step one make some room on all the devices */
        devices = &fs_info->fs_devices->devices;
@@ -3540,7 +3548,13 @@ again:
                        goto loop;
                }
 
-               if ((chunk_type & BTRFS_BLOCK_GROUP_DATA) && !chunk_reserved) {
+               ASSERT(fs_info->data_sinfo);
+               spin_lock(&fs_info->data_sinfo->lock);
+               bytes_used = fs_info->data_sinfo->bytes_used;
+               spin_unlock(&fs_info->data_sinfo->lock);
+
+               if ((chunk_type & BTRFS_BLOCK_GROUP_DATA) &&
+                   !chunk_reserved && !bytes_used) {
                        trans = btrfs_start_transaction(chunk_root, 0);
                        if (IS_ERR(trans)) {
                                mutex_unlock(&fs_info->delete_unused_bgs_mutex);
@@ -3693,10 +3707,8 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
                num_devices--;
        }
        btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
-       allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
-       if (num_devices == 1)
-               allowed |= BTRFS_BLOCK_GROUP_DUP;
-       else if (num_devices > 1)
+       allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE | BTRFS_BLOCK_GROUP_DUP;
+       if (num_devices > 1)
                allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);
        if (num_devices > 2)
                allowed |= BTRFS_BLOCK_GROUP_RAID5;