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Btrfs: eliminate the exceptional root_tree refs=0
The fact that btrfs_root_refs() returned 0 for the tree_root caused bugs in the past, therefore it is set to 1 with this patch and (hopefully) all affected code is adapted to this change. I verified this change by temporarily adding WARN_ON() checks everywhere where btrfs_root_refs() is used, checking whether the logic of the code is changed by btrfs_root_refs() returning 1 instead of 0 for root->root_key.objectid == BTRFS_ROOT_TREE_OBJECTID. With these added checks, I ran the xfstests './check -g auto'. The two roots chunk_root and log_root_tree that are only referenced by the superblock and the log_roots below the log_root_tree still have btrfs_root_refs() == 0, only the tree_root is changed. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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parent
5e01dc7b26
commit
69e9c6c6dc
3 changed files with 10 additions and 15 deletions
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@ -2670,6 +2670,7 @@ int open_ctree(struct super_block *sb,
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btrfs_set_root_node(&tree_root->root_item, tree_root->node);
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tree_root->commit_root = btrfs_root_node(tree_root);
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btrfs_set_root_refs(&tree_root->root_item, 1);
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location.objectid = BTRFS_EXTENT_TREE_OBJECTID;
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location.type = BTRFS_ROOT_ITEM_KEY;
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@ -412,8 +412,7 @@ int btrfs_save_ino_cache(struct btrfs_root *root,
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return 0;
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/* Don't save inode cache if we are deleting this root */
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if (btrfs_root_refs(&root->root_item) == 0 &&
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root != root->fs_info->tree_root)
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if (btrfs_root_refs(&root->root_item) == 0)
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return 0;
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if (!btrfs_test_opt(root, INODE_MAP_CACHE))
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@ -4472,8 +4472,10 @@ void btrfs_evict_inode(struct inode *inode)
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trace_btrfs_inode_evict(inode);
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truncate_inode_pages(&inode->i_data, 0);
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if (inode->i_nlink && (btrfs_root_refs(&root->root_item) != 0 ||
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btrfs_is_free_space_inode(inode)))
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if (inode->i_nlink &&
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((btrfs_root_refs(&root->root_item) != 0 &&
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root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID) ||
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btrfs_is_free_space_inode(inode)))
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goto no_delete;
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if (is_bad_inode(inode)) {
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@ -4490,7 +4492,8 @@ void btrfs_evict_inode(struct inode *inode)
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}
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if (inode->i_nlink > 0) {
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BUG_ON(btrfs_root_refs(&root->root_item) != 0);
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BUG_ON(btrfs_root_refs(&root->root_item) != 0 &&
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root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID);
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goto no_delete;
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}
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@ -4731,14 +4734,7 @@ static void inode_tree_del(struct inode *inode)
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}
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spin_unlock(&root->inode_lock);
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/*
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* Free space cache has inodes in the tree root, but the tree root has a
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* root_refs of 0, so this could end up dropping the tree root as a
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* snapshot, so we need the extra !root->fs_info->tree_root check to
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* make sure we don't drop it.
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*/
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if (empty && btrfs_root_refs(&root->root_item) == 0 &&
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root != root->fs_info->tree_root) {
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if (empty && btrfs_root_refs(&root->root_item) == 0) {
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synchronize_srcu(&root->fs_info->subvol_srcu);
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spin_lock(&root->inode_lock);
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empty = RB_EMPTY_ROOT(&root->inode_tree);
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@ -7857,8 +7853,7 @@ int btrfs_drop_inode(struct inode *inode)
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return 1;
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/* the snap/subvol tree is on deleting */
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if (btrfs_root_refs(&root->root_item) == 0 &&
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root != root->fs_info->tree_root)
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if (btrfs_root_refs(&root->root_item) == 0)
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return 1;
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else
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return generic_drop_inode(inode);
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