Function cache_lookup

freebsd/kern/vfs_cache.c:1926–2032

}

int
cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
    struct timespec *tsp, int *ticksp)
{
	struct namecache *ncp;
	uint32_t hash;
	enum vgetstate vs;
	int error;
	bool whiteout, neg_promote;
	u_short nc_flag;

	MPASS((tsp == NULL && ticksp == NULL) || (tsp != NULL && ticksp != NULL));

#ifdef DEBUG_CACHE
	if (__predict_false(!doingcache)) {
		cnp->cn_flags &= ~MAKEENTRY;
		return (0);
	}
#endif

	if (__predict_false(cnp->cn_nameptr[0] == '.')) {
		if (cnp->cn_namelen == 1)
			return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp));
		if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.')
			return (cache_lookup_dotdot(dvp, vpp, cnp, tsp, ticksp));
	}

	MPASS((cnp->cn_flags & ISDOTDOT) == 0);

	if ((cnp->cn_flags & (MAKEENTRY | NC_KEEPPOSENTRY)) == 0) {
		cache_remove_cnp(dvp, cnp);
		return (0);
	}

	hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
	vfs_smr_enter();

	CK_SLIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
		if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
		    !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
			break;
	}

	if (__predict_false(ncp == NULL)) {
		vfs_smr_exit();
		SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
		    NULL);
		counter_u64_add(nummiss, 1);
		return (0);
	}

	nc_flag = atomic_load_char(&ncp->nc_flag);
	if (nc_flag & NCF_NEGATIVE)
		goto negative_success;

	counter_u64_add(numposhits, 1);
	*vpp = ncp->nc_vp;
	SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name, *vpp);