Btrfs-progs: add --init-extent-tree to btrfsck

In some cases the extent tree can just be so gone there is no point in trying to
figure out how to put it back together.  So add a --init-extent-tree mode which
will zero out the extent tree and then re-add extents for all of the blocks we
find.  This will also undo any balance that was going on at the time of the
crash, this is needed because the reloc tree seems to confuse fsck at the
moment.  With this patch I can put back together a users file system that was
completely gone.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 22 insertions, 9 deletions

diff --git a/extent-tree.c b/extent-tree.c
index 9b381836..6c7229b8 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -3335,19 +3335,16 @@ error:
 	return ret;
 }
 
-int btrfs_make_block_group(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *root, u64 bytes_used,
-			   u64 type, u64 chunk_objectid, u64 chunk_offset,
-			   u64 size)
+struct btrfs_block_group_cache *
+btrfs_add_block_group(struct btrfs_fs_info *fs_info, u64 bytes_used, u64 type,
+		      u64 chunk_objectid, u64 chunk_offset, u64 size)
 {
 	int ret;
 	int bit = 0;
-	struct btrfs_root *extent_root;
 	struct btrfs_block_group_cache *cache;
 	struct extent_io_tree *block_group_cache;
 
-	extent_root = root->fs_info->extent_root;
-	block_group_cache = &root->fs_info->block_group_cache;
+	block_group_cache = &fs_info->block_group_cache;
 
 	cache = kzalloc(sizeof(*cache), GFP_NOFS);
 	BUG_ON(!cache);
@@ -3360,7 +3357,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
 	cache->flags = type;
 	btrfs_set_block_group_flags(&cache->item, type);
 
-	ret = update_space_info(root->fs_info, cache->flags, size, bytes_used,
+	ret = update_space_info(fs_info, cache->flags, size, bytes_used,
 				&cache->space_info);
 	BUG_ON(ret);
 
@@ -3371,13 +3368,29 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
 
 	set_state_private(block_group_cache, chunk_offset,
 			  (unsigned long)cache);
+	set_avail_alloc_bits(fs_info, type);
+
+	return cache;
+}
+
+int btrfs_make_block_group(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root, u64 bytes_used,
+			   u64 type, u64 chunk_objectid, u64 chunk_offset,
+			   u64 size)
+{
+	int ret;
+	struct btrfs_root *extent_root;
+	struct btrfs_block_group_cache *cache;
+
+	cache = btrfs_add_block_group(root->fs_info, bytes_used, type,
+				      chunk_objectid, chunk_offset, size);
+	extent_root = root->fs_info->extent_root;
 	ret = btrfs_insert_item(trans, extent_root, &cache->key, &cache->item,
 				sizeof(cache->item));
 	BUG_ON(ret);
 
 	finish_current_insert(trans, extent_root);
 	ret = del_pending_extents(trans, extent_root);
-	set_avail_alloc_bits(extent_root->fs_info, type);
 	return 0;
 }