Btrfs: Add a clear_cache mount option

If something goes wrong with the free space cache we need a way to make sure
it's not loaded on mount and that it's cleared for everybody.  When you pass the
clear_cache option it will make it so all block groups are setup to be cleared,
which keeps them from being loaded and then they will be truncated when the
transaction is committed.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 137833e1fc26..1a94ee4c4fbb 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8198,6 +8198,8 @@ int btrfs_read_block_groups(struct btrfs_root *root)
         if (cache_gen != 0 &&
             btrfs_super_generation(&root->fs_info->super_copy) != cache_gen)
                 need_clear = 1;
+        if (btrfs_test_opt(root, CLEAR_CACHE))
+                need_clear = 1;
 
         while (1) {
                 ret = find_first_block_group(root, path, &key);