On Mon, Sep 12, 2016 at 09:29:02PM +0200, Miklos Szeredi wrote: > The first patch is actually a bug fix, but I put it into this bunch for > simplicity... > > The rest are really cleanups as well as minor bugfixes that are byproducts > of the cleanups. > > This series builds on the fact that i_op.readlink is already set to > generic_readlink() in 43/50 of the cases. And of those 7 only 4 are doing > something special. So more than 90% of readlinks are/could actually just > call back into get_link. > > The interesting cases are: > > - AFS, which has readlink but not get_link > - proc, that allow jumping while following symlinks > > The first is handled by setting IOP_NOFOLLOW on the inode by the fs. > > The second one is handled by introducing is_following_link() which returns > a bool depending on whether current->nameidata is NULL or not. If it > returns false ->get_link() should behave as ->readlink() did. Otherwise it > should behave as id did previously. > > Builds and boots. Can even read symlinks. I have no problem with "let's get rid of generic_readlink" - not that it bought us much, but sure, if you want to have decision made based upon the combination of flags, let's do it. Just make NULL ->readlink + non-NULL ->get_link() mean generic_readlink(), and we are done. Especially if you do the usual "set the flag on inode the first time we need to check". I also have no problem with overlayfs and ecryptfs assuming that we only deal with normal symlinks. Overloading ->get_link() for procfs-style ones is just plain wrong, though. Your current->nameidata != NULL thing is bloody brittle - what happens if some code triggers those readlinks when called by something during pathname resolution? Sure, right now existing callers won't. But it doesn't take much to grow such a place _and_ have the implications go unnoticed for quite a while. -- 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
