Btrfs: check UUID tree during mount if required

[linux-2.6-block.git] / fs / btrfs / volumes.c

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 4066803fe765a18fa224cd314431340fbc6b091b..75bdea6bf188cd5411bc8c9e5561322036ca10f4 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3559,10 +3559,76 @@ out:
        btrfs_free_path(path);
        if (ret)
                pr_warn("btrfs: btrfs_uuid_scan_kthread failed %d\n", ret);
+       else
+               fs_info->update_uuid_tree_gen = 1;
        up(&fs_info->uuid_tree_rescan_sem);
        return 0;
 }
 
+/*
+ * Callback for btrfs_uuid_tree_iterate().
+ * returns:
+ * 0   check succeeded, the entry is not outdated.
+ * < 0 if an error occured.
+ * > 0 if the check failed, which means the caller shall remove the entry.
+ */
+static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
+                                      u8 *uuid, u8 type, u64 subid)
+{
+       struct btrfs_key key;
+       int ret = 0;
+       struct btrfs_root *subvol_root;
+
+       if (type != BTRFS_UUID_KEY_SUBVOL &&
+           type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
+               goto out;
+
+       key.objectid = subid;
+       key.type = BTRFS_ROOT_ITEM_KEY;
+       key.offset = (u64)-1;
+       subvol_root = btrfs_read_fs_root_no_name(fs_info, &key);
+       if (IS_ERR(subvol_root)) {
+               ret = PTR_ERR(subvol_root);
+               if (ret == -ENOENT)
+                       ret = 1;
+               goto out;
+       }
+
+       switch (type) {
+       case BTRFS_UUID_KEY_SUBVOL:
+               if (memcmp(uuid, subvol_root->root_item.uuid, BTRFS_UUID_SIZE))
+                       ret = 1;
+               break;
+       case BTRFS_UUID_KEY_RECEIVED_SUBVOL:
+               if (memcmp(uuid, subvol_root->root_item.received_uuid,
+                          BTRFS_UUID_SIZE))
+                       ret = 1;
+               break;
+       }
+
+out:
+       return ret;
+}
+
+static int btrfs_uuid_rescan_kthread(void *data)
+{
+       struct btrfs_fs_info *fs_info = (struct btrfs_fs_info *)data;
+       int ret;
+
+       /*
+        * 1st step is to iterate through the existing UUID tree and
+        * to delete all entries that contain outdated data.
+        * 2nd step is to add all missing entries to the UUID tree.
+        */
+       ret = btrfs_uuid_tree_iterate(fs_info, btrfs_check_uuid_tree_entry);
+       if (ret < 0) {
+               pr_warn("btrfs: iterating uuid_tree failed %d\n", ret);
+               up(&fs_info->uuid_tree_rescan_sem);
+               return ret;
+       }
+       return btrfs_uuid_scan_kthread(data);
+}
+
 int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
 {
        struct btrfs_trans_handle *trans;
@@ -3596,6 +3662,7 @@ int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
        down(&fs_info->uuid_tree_rescan_sem);
        task = kthread_run(btrfs_uuid_scan_kthread, fs_info, "btrfs-uuid");
        if (IS_ERR(task)) {
+               /* fs_info->update_uuid_tree_gen remains 0 in all error case */
                pr_warn("btrfs: failed to start uuid_scan task\n");
                up(&fs_info->uuid_tree_rescan_sem);
                return PTR_ERR(task);
@@ -3604,6 +3671,22 @@ int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
        return 0;
 }
 
+int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info)
+{
+       struct task_struct *task;
+
+       down(&fs_info->uuid_tree_rescan_sem);
+       task = kthread_run(btrfs_uuid_rescan_kthread, fs_info, "btrfs-uuid");
+       if (IS_ERR(task)) {
+               /* fs_info->update_uuid_tree_gen remains 0 in all error case */
+               pr_warn("btrfs: failed to start uuid_rescan task\n");
+               up(&fs_info->uuid_tree_rescan_sem);
+               return PTR_ERR(task);
+       }
+
+       return 0;
+}
+
 /*
  * shrinking a device means finding all of the device extents past
  * the new size, and then following the back refs to the chunks.