On Fri, Aug 23, 2013 at 4:03 AM, Miao Xie <miaox@xxxxxxxxxxxxxx> wrote:
> On fri, 23 Aug 2013 10:34:42 +0200, Stefan Behrens wrote:
>> Mitch Harder noticed that the patch 3c64a1a mentioned in the subject
>> line was causing a kernel BUG() on snapshot deletion.
>>
>> The patch was wrong. It did not handle cached roots correctly. The
>> check for root_refs == 0 was removed everywhere where
>> btrfs_read_fs_root_no_name() had been used to retrieve the root,
>> because this check was already dealt with in
>> btrfs_read_fs_root_no_name(). But in the case when the root was
>> found in the cache, there was no such check.
>>
>> This patch adds the missing check in the case where the root is
>> found in the cache.
>>
>> Reported-by: Mitch Harder <mitch.harder@xxxxxxxxxxxxxxxx>
>> Signed-off-by: Stefan Behrens <sbehrens@xxxxxxxxxxxxxxxx>
>> ---
>> fs/btrfs/disk-io.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>> index 43ec3c6..7078554 100644
>> --- a/fs/btrfs/disk-io.c
>> +++ b/fs/btrfs/disk-io.c
>> @@ -1583,8 +1583,11 @@ struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
>> ERR_PTR(-ENOENT);
>> again:
>> root = btrfs_lookup_fs_root(fs_info, location->objectid);
>> - if (root)
>> + if (root) {
>> + if (btrfs_root_refs(&root->root_item) == 0)
>> + return ERR_PTR(-ENOENT);
>> return root;
>> + }
>
> It seems good to me.
>
> Reviewed-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
>
>>
>> root = btrfs_read_fs_root(fs_info->tree_root, location);
>> if (IS_ERR(root))
>>
Tested-by: Mitch Harder <mitch.harder@xxxxxxxxxxxxxxxx>
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