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Commit 834328a8 authored by Jan Schmidt's avatar Jan Schmidt
Browse files

Btrfs: tree mod log's old roots could still be part of the tree 



Tree mod log treated old root buffers as always empty buffers when starting
the rewind operations. However, the old root may still be part of the
current tree at a lower level, with still some valid entries.

Signed-off-by: default avatarJan Schmidt <list.btrfs@jan-o-sch.net>
parent ba1bfbd5

fs/btrfs/ctree.c

+21 −4
Original line number Diff line number Diff line
@@ -1239,6 +1239,7 @@ get_old_root(struct btrfs_root *root, u64 time_seq) 
	struct tree_mod_root *old_root = NULL;

	u64 old_generation = 0;

	u64 logical;

	u32 blocksize;



	eb = btrfs_read_lock_root_node(root);

	tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
@@ -1254,12 +1255,28 @@ get_old_root(struct btrfs_root *root, u64 time_seq) 
	}



	tm = tree_mod_log_search(root->fs_info, logical, time_seq);

	if (old_root)

	if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {

		btrfs_tree_read_unlock(root->node);

		free_extent_buffer(root->node);

		blocksize = btrfs_level_size(root, old_root->level);

		eb = read_tree_block(root, logical, blocksize, 0);

		if (!eb) {

			pr_warn("btrfs: failed to read tree block %llu from get_old_root\n",

				logical);

			WARN_ON(1);

		} else {

			eb = btrfs_clone_extent_buffer(eb);

		}

	} else if (old_root) {

		btrfs_tree_read_unlock(root->node);

		free_extent_buffer(root->node);

		eb = alloc_dummy_extent_buffer(logical, root->nodesize);

	else

	} else {

		eb = btrfs_clone_extent_buffer(root->node);

		btrfs_tree_read_unlock(root->node);

		free_extent_buffer(root->node);

	}



	if (!eb)

		return NULL;

	btrfs_tree_read_lock(eb);