Thank you for your answer. I'm so sorry I asked my personal project question here. Yes, I will use a shared disk file system. Best regards, Daegyu 2019-10-03 4:39 GMT+09:00, Theodore Y. Ts'o <tytso@xxxxxxx>: > On Wed, Oct 02, 2019 at 11:42:47PM +0900, Daegyu Han wrote: >> Thank you for your consideration. >> >> Okay, I will check ocfs2 out. >> >> By the way, is there any possibility to implement this functionality >> in the vfs layer? >> >> I looked at the dcache.c, inode.c, and mm/vmscan.c code and looked at >> several functions, >> and as you said, they seem to have way complex logic. >> >> The logic I thought was to release the desired dentry, dentry_kill() >> the negative dentry, and break the inodes of the file that had that >> dentry. > > The short version is that objects have dependencies on other objects. > For example, a file descriptor object has a reference to the dentry of > the file which is open. A file dentry or directory dentry object > references its parent directory's dentry object, etc. You can not > evict an object when other objects have references on it --- otherwise > those references become dangling pointers, Which Would Be Bad. > > There are solutions for remote file systems (network, clustered, and > shared disk file systems). So the VFS layer can support these file > systems quite well. Look at ceph, nfs, ofs2, and gfs for examples for > that. But it's *complicated* because doing it in a way which is > highly performant, both for remote file systems, and as well as > supporting high-performance local disk file systems, is a lot more > than your very simple-minded, "just kill the dentry/inode structures > and reread them from disk". > > Are you trying to do this for a university class project or some such? > If so, we're not here to do your homework for you. If you want a > practical solution, please use an existing shared-disk or networked > file system. > > Best regards, > > - Ted >
