On Wed, 24 Jun 2009, Al Viro wrote: > > i_filesystem_fop is certainly bogus, but why do we want to bother with > file_operations at all? > > Unless you really insist on unlimited use of ioctl(2) on such beasts (and > any users will be non-portable for obvious reasons anyway), there's no need > to go anywhere near ->open() *or* ->f_op in general. A lot of filesystems (especially network filesystems) want to do something special when you open a node on them. NFS, for example, does that whole alloc_nfs_open_context() thing to keep track of RPC credentials etc. It's where things like "filp->f_private" get set etc. So if you don't call open(), you'll not initialize the filp sufficiently to do lots of operations. But yes: > Just add new methods to ->i_op (and we already have that coming from > fs code) and teach do_filp_open() to > * call permission() with new flag (MAY_TALK_TO_FS_NODE) for such > open() > * do not die with -ELOOP on symlinks if we have O_NOFOLLOW + your flag > * do not call ->f_op->open() at all for such open() > and we are all set. Hell, we can even teach sys_ioctl() that given set > of ioctls maps to calls of our new methods. Taken from ->i_op... Sure. That will work, but I do think that it's going to be more hacky than just trying to make the file descriptor look as real as possible, and just calling "open" on it. But I don't really have any strong opinions. Linus -- 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
