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Btrfs: eliminate the exceptional root_tree refs=0

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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>
This commit is contained in:
Stefan Behrens
2013-09-05 16:58:43 +02:00
committed by Chris Mason
parent 5e01dc7b26
commit 69e9c6c6dc
3 changed files with 10 additions and 15 deletions
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3
fs/btrfs/inode-map.c
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@@ -412,8 +412,7 @@ int btrfs_save_ino_cache(struct btrfs_root *root,
return 0;
/* Don't save inode cache if we are deleting this root */
if (btrfs_root_refs(&root->root_item) == 0 &&
root != root->fs_info->tree_root)
if (btrfs_root_refs(&root->root_item) == 0)
return 0;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))