On Sun, 2006-09-17 at 22:43 +0200, Miklos Szeredi wrote: > Consider the scenario where systems A and B share a filesystem mounted > on /mnt. > > A: cd /mnt/a/b > B: mv /mnt/a/b /mnt/a/c/d > A: ls /mnt/a/c/d > > So in third step the lookup returns a cached inode, to which a cached > dentry with positive refcount already refers. > > I can basically think of two possibilities: > > 1) instantiate new dentry 'd' with the inode > 2) move the old dentry 'b' to the new dentry 'd' > > With 1, there's a problem of directory aliasing, which means the VFS > doesn't ensure any more that directory loops can't happen. NFS looks > like it does this, and relies on the server to avoid loops. > > 2 suffers from locking problems, since lookup already holds a i_mutex > on /mnt/a/c so it can't acquire either the rename_mutex or i_mutex on > /mnt/a which would be needed to safely move the dentry. 2 also suffers from the problem of loops. How do you fix it to deal with the case of A: cd /mnt/a/b B: mv /mnt/a/b /mnt B: mv /mnt/a /mnt/b A: cd a Cheers, Trond - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
