2022-10-02 9:39 GMT+09:00, Al Viro <viro@xxxxxxxxxxxxxxxxxx>:
> On Wed, Sep 21, 2022 at 07:43:38AM +0900, Namjae Jeon wrote:
>
>
>> -int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *name,
>> - unsigned int flags, struct path *path, bool caseless)
>> +int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name,
>> + unsigned int flags, struct path *path,
>> + bool caseless)
>> {
>> struct ksmbd_share_config *share_conf = work->tcon->share_conf;
>> int err;
>> + struct path parent_path;
>>
>> + err = ksmbd_vfs_path_parent_lookup(share_conf, name, flags,
>> + &parent_path);
>> flags |= LOOKUP_BENEATH;
>> - err = vfs_path_lookup(share_conf->vfs_path.dentry,
>> - share_conf->vfs_path.mnt,
>> - name,
>> - flags,
>> - path);
>> - if (!err)
>> - return 0;
>> + if (!err) {
>> + err = vfs_path_lookup(share_conf->vfs_path.dentry,
>> + share_conf->vfs_path.mnt,
>> + name,
>> + flags,
>> + path);
>> + if (!err)
>> + goto lock_parent;
>> + path_put(&parent_path);
>
> This is wrong. You have already resolved the sucker to parent
> + last component. Now you ask vfs_path_lookup() to
> * redo the same thing, hopefully arriving to the same
> spot.
> * look the last component up in wherever it has arrived.
> then you
> * lock the place you'd originally arrived at
> * check if the result of last lookup is its child (i.e.
> it hadn't moved since we looked it up and lookup hopefully
> arrived to the same spot for parent.
>
> That's far too convoluted...
Right. Need to avoid repeat lookup.
I have called vfs_path_lookup() again to avoid accessing out of share
and get struct path of child. I may try to change vfs_path_lookup()(or
create new vfs function) to return struct path of parent as well
struct path of child... ?
Thanks for your review!
>
