On Tue, Mar 21, 2017 at 7:51 AM, Omar Sandoval <osandov@xxxxxxxxxxx> wrote: > */ > -int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) > +int vfs_link(struct dentry *old_dentry, struct inode *dir, > + struct dentry *new_dentry, struct inode **delegated_inode, > + unsigned int flags) > { > struct inode *inode = old_dentry->d_inode; > + struct inode *target = new_dentry->d_inode; > unsigned max_links = dir->i_sb->s_max_links; > int error; > > if (!inode) > return -ENOENT; > > - error = may_create(dir, new_dentry); > + if (target) { > + if (flags & AT_REPLACE) > + error = may_delete(dir, new_dentry, d_is_dir(old_dentry)); > + else > + error = -EEXIST; > + } else { > + error = may_create(dir, new_dentry); > + } This looks bogus. In particular, that "may_delete()" cannot be right. It should still *also* have the right to create something in that directory. But even if you replace it with checks for both deletion _and_ creation, it won't be right, since the test for d_is_negative() on the target in may_delete() looks wrong for this situation. Normally, you cannot delete a negative entry (think of what that would do in a overlay situation), but it should still be ok to link a positive entry on top of a negative one. Also, I think the above is incorrect for yet another case: moving somethign on top of a directory should be disallowed. We do later on check that the *source* isn't a directory (since you can't link directories), but I'm not seeing where you'd be checking that you don't move over a directory either. So I don't think this patch is acceptable as such. I also suspect that it should be done in multiple phases. Linus