Btrfs: eliminate the exceptional root_tree refs=0
authorStefan Behrens <sbehrens@giantdisaster.de>
Thu, 5 Sep 2013 14:58:43 +0000 (16:58 +0200)
committerChris Mason <chris.mason@fusionio.com>
Tue, 12 Nov 2013 02:49:26 +0000 (21:49 -0500)
commit69e9c6c6dc87587d8846e447febedefe037c14f8
tree557fc35afdf3bbee9ce0f46a2ce16ce1c386133c
parent5e01dc7b26d9f24f39abace5da98ccbd6a5ceb52
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>
fs/btrfs/disk-io.c
fs/btrfs/inode-map.c
fs/btrfs/inode.c