Btrfs: Add locking around volume management (device add/remove/balance)

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 44 insertions, 14 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 4e7cee27aab5..5e6ee7a6f738 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -56,6 +56,18 @@ void btrfs_unlock_volumes(void)
         mutex_unlock(&uuid_mutex);
 }
 
+static void lock_chunks(struct btrfs_root *root)
+{
+        mutex_lock(&root->fs_info->alloc_mutex);
+        mutex_lock(&root->fs_info->chunk_mutex);
+}
+
+static void unlock_chunks(struct btrfs_root *root)
+{
+        mutex_unlock(&root->fs_info->alloc_mutex);
+        mutex_unlock(&root->fs_info->chunk_mutex);
+}
+
 int btrfs_cleanup_fs_uuids(void)
 {
         struct btrfs_fs_devices *fs_devices;
@@ -822,6 +834,7 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
         key.type = BTRFS_DEV_ITEM_KEY;
         key.offset = device->devid;
+        lock_chunks(root);
 
         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
         if (ret < 0)
@@ -856,6 +869,7 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
                                     total_bytes - 1);
 out:
         btrfs_free_path(path);
+        unlock_chunks(root);
         btrfs_commit_transaction(trans, root);
         return ret;
 }
@@ -870,9 +884,8 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
         u64 devid;
         int ret = 0;
 
-        mutex_lock(&root->fs_info->alloc_mutex);
-        mutex_lock(&root->fs_info->chunk_mutex);
         mutex_lock(&uuid_mutex);
+        mutex_lock(&root->fs_info->volume_mutex);
 
         all_avail = root->fs_info->avail_data_alloc_bits |
                 root->fs_info->avail_system_alloc_bits |
@@ -988,9 +1001,8 @@ error_close:
         if (bdev)
                 close_bdev_excl(bdev);
 out:
+        mutex_unlock(&root->fs_info->volume_mutex);
         mutex_unlock(&uuid_mutex);
-        mutex_unlock(&root->fs_info->chunk_mutex);
-        mutex_unlock(&root->fs_info->alloc_mutex);
         return ret;
 }
 
@@ -1010,10 +1022,10 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
                 return -EIO;
         }
 
-        mutex_lock(&root->fs_info->alloc_mutex);
-        mutex_lock(&root->fs_info->chunk_mutex);
+        mutex_lock(&root->fs_info->volume_mutex);
 
         trans = btrfs_start_transaction(root, 1);
+        lock_chunks(root);
         devices = &root->fs_info->fs_devices->devices;
         list_for_each(cur, devices) {
                 device = list_entry(cur, struct btrfs_device, dev_list);
@@ -1065,9 +1077,9 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         root->fs_info->fs_devices->num_devices++;
         root->fs_info->fs_devices->open_devices++;
 out:
+        unlock_chunks(root);
         btrfs_end_transaction(trans, root);
-        mutex_unlock(&root->fs_info->chunk_mutex);
-        mutex_unlock(&root->fs_info->alloc_mutex);
+        mutex_unlock(&root->fs_info->volume_mutex);
 
         return ret;
 
@@ -1122,7 +1134,7 @@ out:
         return ret;
 }
 
-int btrfs_grow_device(struct btrfs_trans_handle *trans,
+static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
                       struct btrfs_device *device, u64 new_size)
 {
         struct btrfs_super_block *super_copy =
@@ -1134,6 +1146,16 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
         return btrfs_update_device(trans, device);
 }
 
+int btrfs_grow_device(struct btrfs_trans_handle *trans,
+                      struct btrfs_device *device, u64 new_size)
+{
+        int ret;
+        lock_chunks(device->dev_root);
+        ret = __btrfs_grow_device(trans, device, new_size);
+        unlock_chunks(device->dev_root);
+        return ret;
+}
+
 static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root,
                             u64 chunk_tree, u64 chunk_objectid,
@@ -1234,6 +1256,8 @@ int btrfs_relocate_chunk(struct btrfs_root *root,
         trans = btrfs_start_transaction(root, 1);
         BUG_ON(!trans);
 
+        lock_chunks(root);
+
         /*
          * step two, delete the device extents and the
          * chunk tree entries
@@ -1278,6 +1302,7 @@ int btrfs_relocate_chunk(struct btrfs_root *root,
         /* once for us */
         free_extent_map(em);
 
+        unlock_chunks(root);
         btrfs_end_transaction(trans, root);
         return 0;
 }
@@ -1308,8 +1333,7 @@ int btrfs_balance(struct btrfs_root *dev_root)
         struct btrfs_key found_key;
 
 
-        BUG(); /* FIXME, needs locking */
-
+        mutex_lock(&dev_root->fs_info->volume_mutex);
         dev_root = dev_root->fs_info->dev_root;
 
         /* step one make some room on all the devices */
@@ -1355,13 +1379,14 @@ int btrfs_balance(struct btrfs_root *dev_root)
 
                 ret = btrfs_previous_item(chunk_root, path, 0,
                                           BTRFS_CHUNK_ITEM_KEY);
-                if (ret) {
+                if (ret)
                         break;
-                }
+
                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
                                       path->slots[0]);
                 if (found_key.objectid != key.objectid)
                         break;
+
                 chunk = btrfs_item_ptr(path->nodes[0],
                                        path->slots[0],
                                        struct btrfs_chunk);
@@ -1370,16 +1395,17 @@ int btrfs_balance(struct btrfs_root *dev_root)
                 if (key.offset == 0)
                         break;
 
+                btrfs_release_path(chunk_root, path);
                 ret = btrfs_relocate_chunk(chunk_root,
                                            chunk_root->root_key.objectid,
                                            found_key.objectid,
                                            found_key.offset);
                 BUG_ON(ret);
-                btrfs_release_path(chunk_root, path);
         }
         ret = 0;
 error:
         btrfs_free_path(path);
+        mutex_unlock(&dev_root->fs_info->volume_mutex);
         return ret;
 }
 
@@ -1419,14 +1445,18 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 
         path->reada = 2;
 
+        lock_chunks(root);
+
         device->total_bytes = new_size;
         ret = btrfs_update_device(trans, device);
         if (ret) {
+                unlock_chunks(root);
                 btrfs_end_transaction(trans, root);
                 goto done;
         }
         WARN_ON(diff > old_total);
         btrfs_set_super_total_bytes(super_copy, old_total - diff);
+        unlock_chunks(root);
         btrfs_end_transaction(trans, root);
 
         key.objectid = device->devid;