Function cache_fplookup_trailingslash

freebsd/kern/vfs_cache.c:5394–5508

* Handle trailing slashes (e.g., "foo/"). * * If a trailing slash is found the terminal vnode must be a directory. * Regular lookup shortens the path by nulifying the first trailing slash and * sets the TRAILINGSLASH flag to denote this took place. There are several * checks on it performed later. * * Similarly to spurious slashes, lockless lookup handles this in a speculative * manner rel

 * Only plain lookups are supported for now to restrict corner cases to handle.
 */
static int __noinline
cache_fplookup_trailingslash(struct cache_fpl *fpl)
{
#ifdef INVARIANTS
	size_t ni_pathlen;
#endif
	struct nameidata *ndp;
	struct componentname *cnp;
	struct namecache *ncp;
	struct vnode *tvp;
	char *cn_nameptr_orig, *cn_nameptr_slash;
	seqc_t tvp_seqc;
	u_char nc_flag;

	ndp = fpl->ndp;
	cnp = fpl->cnp;
	tvp = fpl->tvp;
	tvp_seqc = fpl->tvp_seqc;

	MPASS(fpl->dvp == fpl->tvp);
	KASSERT(cache_fpl_istrailingslash(fpl),
	    ("%s: expected trailing slash at %p; string [%s]\n", __func__, fpl->nulchar - 1,
	    cnp->cn_pnbuf));
	KASSERT(cnp->cn_nameptr[0] == '\0',
	    ("%s: expected nul char at %p; string [%s]\n", __func__, &cnp->cn_nameptr[0],
	    cnp->cn_pnbuf));
	KASSERT(cnp->cn_namelen == 0,
	    ("%s: namelen 0 but got %ld; string [%s]\n", __func__, cnp->cn_namelen,
	    cnp->cn_pnbuf));
	MPASS(cnp->cn_nameptr > cnp->cn_pnbuf);

	if (cnp->cn_nameiop != LOOKUP) {
		return (cache_fpl_aborted(fpl));
	}

	if (__predict_false(tvp->v_type != VDIR)) {
		if (!vn_seqc_consistent(tvp, tvp_seqc)) {
			return (cache_fpl_aborted(fpl));
		}
		cache_fpl_smr_exit(fpl);
		return (cache_fpl_handled_error(fpl, ENOTDIR));
	}

	/*
	 * Denote the last component.
	 */
	ndp->ni_next = &cnp->cn_nameptr[0];
	MPASS(cache_fpl_islastcn(ndp));

	/*
	 * Unwind trailing slashes.
	 */
	cn_nameptr_orig = cnp->cn_nameptr;
	while (cnp->cn_nameptr >= cnp->cn_pnbuf) {
		cnp->cn_nameptr--;
		if (cnp->cn_nameptr[0] != '/') {
			break;
		}