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Btrfs: Fix uninitialized root flags for subvolumes

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root_item->flags and root_item->byte_limit are not initialized when
a subvolume is created. This bug is not revealed until we added
readonly snapshot support - now you mount a btrfs filesystem and you
may find the subvolumes in it are readonly.

To work around this problem, we steal a bit from root_item->inode_item->flags,
and use it to indicate if those fields have been properly initialized.
When we read a tree root from disk, we check if the bit is set, and if
not we'll set the flag and initialize the two fields of the root item.

Reported-by: Andreas Philipp <philipp.andreas@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Tested-by: Andreas Philipp <philipp.andreas@gmail.com>
cc: stable@kernel.org
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Li Zefan 2011-03-28 02:01:25 +00:00 • committed by Chris Mason
parent adae52b94e
commit 08fe4db170
5 changed files with 30 additions and 1 deletions
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4
fs/btrfs/disk-io.c
View file

@ -1276,8 +1276,10 @@ struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_root *tree_root,
root->commit_root = btrfs_root_node(root);
BUG_ON(!root->node);
out:
if (location->objectid != BTRFS_TREE_LOG_OBJECTID)
if (location->objectid != BTRFS_TREE_LOG_OBJECTID) {
root->ref_cows = 1;
btrfs_check_and_init_root_item(&root->root_item);
}
return root;
}