2 files changed, 4 insertions, 3 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0ce93ac17f69..ddb4bc1252ad 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2453,10 +2453,10 @@ static long btrfs_ioctl_fs_info(struct btrfs_root *root, void __user *arg)
         if (!fi_args)
                 return -ENOMEM;
 
+        mutex_lock(&fs_devices->device_list_mutex);
         fi_args->num_devices = fs_devices->num_devices;
         memcpy(&fi_args->fsid, root->fs_info->fsid, sizeof(fi_args->fsid));
 
-        mutex_lock(&fs_devices->device_list_mutex);
         list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
                 if (device->devid > fi_args->max_id)
                         fi_args->max_id = device->devid;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 3f1c2c200691..74614e3b5ad3 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -492,10 +492,10 @@ static noinline int device_list_add(const char *path,
 
                 mutex_lock(&fs_devices->device_list_mutex);
                 list_add_rcu(&device->dev_list, &fs_devices->devices);
+                fs_devices->num_devices++;
                 mutex_unlock(&fs_devices->device_list_mutex);
 
                 device->fs_devices = fs_devices;
-                fs_devices->num_devices++;
         } else if (!device->name || strcmp(device->name->str, path)) {
                 name = rcu_string_strdup(path, GFP_NOFS);
                 if (!name)
@@ -1852,7 +1852,6 @@ static int btrfs_prepare_sprout(struct btrfs_root *root)
         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
         list_splice_init_rcu(&fs_devices->devices, &seed_devices->devices,
                               synchronize_rcu);
-        mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 
         list_splice_init(&fs_devices->alloc_list, &seed_devices->alloc_list);
         list_for_each_entry(device, &seed_devices->devices, dev_list) {
@@ -1868,6 +1867,8 @@ static int btrfs_prepare_sprout(struct btrfs_root *root)
         generate_random_uuid(fs_devices->fsid);
         memcpy(root->fs_info->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
         memcpy(disk_super->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
+        mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+
         super_flags = btrfs_super_flags(disk_super) &
                       ~BTRFS_SUPER_FLAG_SEEDING;
         btrfs_set_super_flags(disk_super, super_flags);