On Wed, Nov 13, 2019 at 01:44:14PM +1100, Aleksa Sarai wrote:
On 2019-11-13, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
On Tue, Nov 05, 2019 at 08:05:49PM +1100, Aleksa Sarai wrote:
@@ -2277,12 +2277,20 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
nd->m_seq = read_seqbegin(&mount_lock);
- /* Figure out the starting path and root (if needed). */
- if (*s == '/') {
+ /* Absolute pathname -- fetch the root. */
+ if (flags & LOOKUP_IN_ROOT) {
+ /* With LOOKUP_IN_ROOT, act as a relative path. */
+ while (*s == '/')
+ s++;
Er... Why bother skipping slashes? I mean, not only link_path_walk()
will skip them just fine, you are actually risking breakage in this:
if (*s && unlikely(!d_can_lookup(dentry))) {
fdput(f);
return ERR_PTR(-ENOTDIR);
}
which is downstream from there with you patch, AFAICS.
I switched to stripping the slashes at your suggestion a few revisions
ago[1], and had (wrongly) assumed we needed to handle "/" somehow in
path_init(). But you're quite right about link_path_walk() -- and I'd be
more than happy to drop it.
That, IIRC, was about untangling the weirdness around multiple calls of
dirfd_path_init() and basically went "we might want just strip the slashes
in case of that flag very early in the entire thing, so that later the
normal logics for absolute/relative would DTRT". Since your check is
right next to checking for absolute pathnames (and not in the very
beginning of path_init()), we might as well turn the check for
absolute pathname into *s == '/' && !(flags & LOOKUP_IN_ROOT) and be
done with that.
