Hello I try to summarize the thing so far.
NetBSD filesystems implement advisory locks, where the only place the filesystem actually check locks as VOP_ADVLOCK. Any other operation performed on a file region locked by someone else succeeds: the locks are only advisory, and it is the application duty to enforce it. The GLusterFS people are working to implement mandatory locks, where the filesystem actually enforces locks on any operation: if you write to a region locked by someone else, you get a failure. Mandatory locks must be implemented at the filesystem level, because in the distributed filesystem case, the local kernel knows nothing about locks sets form other machines. It requires the filesystem to distinguish operations on different struct file for a given vnode, because a lock may be acquired for a struct file and not for another one. Currently NetBSD does not pass this information to filesystems. I proposed a patch that embeds the required information in struct cred: https://ftp.espci.fr/shadow/manu/filecred1.patch Ome expresse dissatisfaction with the approach, ostly because struct cred would not be the right place. Doing it another was means modifying the VFS interface to add a reference to struct file where needed (that is: anything that touch file content). Would that approach be better? If the struct cred way is preferred, feedback on the actual implementation on the above patch will be apprciated. For the sake of completeness: once VFS support is there, PUFFS and PERFUSE must be improved so that the new informaiton is sent to FUSE filesystems. I have not yet worked on that part. -- Emmanuel Dreyfus m...@netbsd.org
