On Tue, Jul 14, 2009 at 02:18:44PM -0400, Erez Zadok wrote: > In message <20090713192743.GA27582@shell>, Valerie Aurora writes: > > During the last FS summit, Al Viro suggested creating a superblock > > level read-only marker so that union mounts could guarantee that the > > underlying fs would not become writable. This patch implements the > > VFS support, but doesn't add any users. The patch making union mounts > > use the support is in our union mounts tree. I think we also need > > some way to pass this through NFS mounts, since a read-only NFS mount > > for the bottom layer of a union mount is a common use case. > > > > -VAL > [...] > > Val, I've often wondered if a generic readonly superblock solution will > obviate the need for the sb->s_vfs_rename_mutex "kludge" (as commented in > fs.h) and the whole way directory-renames are done wrt locking. Can the > rename code be the first user of such patch, or the patch isn't quite ready > for this? I'm afraid not! With this patch, you can only mark the superblock (and all associated mounts) read-only if no files are open for writing - not exactly the common case during a directory rename. So no, it can't replace the rename mutex, at least in its current form. -VAL -- 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
