On Fri, 8 Jan 2010, Trond Myklebust wrote: > > How about something like the following. I chose to wrap the call to > do_mmap_pgoff() instead of making a special ->pre_mmap(), since that > seems more consistent with the way we handle ->read() and ->write(). I still don't think that you can ever do mmap _and_ readdir on the same inode, so there's something wrong with the lockdep annotations. See my earlier mail about putting directory inodes in a different class from non-directory inodes, and the email after that that points out that we already do: - inode_init_always(): lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key); - unlock_new_inode() (for directories): lockdep_set_class(&inode->i_mutex, &type->i_mutex_dir_key); and I suspect that the reason why NFS triggers lockdep problems is that NFS probably plays some game with inodes (presumably the root inode) that ends up bypassing the normal new-inode handling. In short - I really don't think this issue merits VFS-level (or VM, whatever you want to call it) hooks. There's a bug there, but I don't think you're actually fixing the right thing. And _especially_ not the way you did it, where the filesystem can wrap the whole complex do_mmap_pgoff. The NFS use you have doesn't seem too bad, but anybody who tries to be clever and avoid "generic_mmap_do_pgoff()" would immediately be a major disaster. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
