 @@ -1,1463 +1,1459 @@
-/*	$NetBSD: vfs_cache.c,v 1.140 2020/04/22 21:35:52 ad Exp $	*/
+/*	$NetBSD: vfs_cache.c,v 1.141 2020/04/23 22:58:36 ad Exp $	*/
 /*-
  * Copyright (c) 2008, 2019, 2020 The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Andrew Doran.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 /*
  * Copyright (c) 1989, 1993
  *	The Regents of the University of California.  All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
+ *
  *	@(#)vfs_cache.c	8.3 (Berkeley) 8/22/94
  */
 /*
  * Name caching:
+ *
  *	Names found by directory scans are retained in a cache for future
  *	reference.  It is managed LRU, so frequently used names will hang
  *	around.  The cache is indexed by hash value obtained from the name.
+ *
  *	The name cache is the brainchild of Robert Elz and was introduced in
  *	4.3BSD.  See "Using gprof to Tune the 4.2BSD Kernel", Marshall Kirk
  *	McKusick, May 21 1984.
+ *
  * Data structures:
+ *
  *	Most Unix namecaches very sensibly use a global hash table to index
  *	names.  The global hash table works well, but can cause concurrency
  *	headaches for the kernel hacker.  In the NetBSD 10.0 implementation
  *	we are not sensible, and use a per-directory data structure to index
  *	names, but the cache otherwise functions the same.
+ *
  *	The index is a red-black tree.  There are no special concurrency
  *	requirements placed on it, because it's per-directory and protected
  *	by the namecache's per-directory locks.  It should therefore not be
  *	difficult to experiment with other types of index.
+ *
  *	Each cached name is stored in a struct namecache, along with a
  *	pointer to the associated vnode (nc_vp).  Names longer than a
  *	maximum length of NCHNAMLEN are allocated with kmem_alloc(); they
  *	occur infrequently, and names shorter than this are stored directly
  *	in struct namecache.  If it is a "negative" entry, (i.e. for a name
  *	that is known NOT to exist) the vnode pointer will be NULL.
+ *
  *	For a directory with 3 cached names for 3 distinct vnodes, the
  *	various vnodes and namecache structs would be connected like this
  *	(the root is at the bottom of the diagram):
+ *
  *          ...
  *           ^
  *           |- vi_nc_tree
  *           |
  *      +----o----+               +---------+               +---------+
  *      |  VDIR   |               |  VCHR   |               |  VREG   |
  *      |  vnode  o-----+         |  vnode  o-----+         |  vnode  o------+
  *      +---------+     |         +---------+     |         +---------+      |
  *           ^          |              ^          |              ^           |
  *           |- nc_vp   |- vi_nc_list  |- nc_vp   |- vi_nc_list  |- nc_vp    |
  *           |          |              |          |              |           |
  *      +----o----+     |         +----o----+     |         +----o----+      |
  *  +---onamecache|<----+     +---onamecache|<----+     +---onamecache|<-----+
  *  |   +---------+           |   +---------+           |   +---------+
  *  |        ^                |        ^                |        ^
  *  |        |                |        |                |        |
  *  |        |  +----------------------+                |        |
  *  |-nc_dvp | +-------------------------------------------------+
  *  |        |/- vi_nc_tree   |                         |
  *  |        |                |- nc_dvp                 |- nc_dvp
  *  |   +----o----+           |                         |
  *  +-->|  VDIR   |<----------+                         |
  *      |  vnode  |<------------------------------------+
  *      +---------+
+ *
  *      START HERE
+ *
  * Replacement:
+ *
  *	As the cache becomes full, old and unused entries are purged as new
  *	entries are added.  The synchronization overhead in maintaining a
  *	strict ordering would be prohibitive, so the VM system's "clock" or
  *	"second chance" page replacement algorithm is aped here.  New
  *	entries go to the tail of the active list.  After they age out and
  *	reach the head of the list, they are moved to the tail of the
  *	inactive list.  Any use of the deactivated cache entry reactivates
  *	it, saving it from impending doom; if not reactivated, the entry
  *	eventually reaches the head of the inactive list and is purged.
+ *
  * Concurrency:
+ *
  *	From a performance perspective, cache_lookup(nameiop == LOOKUP) is
  *	what really matters; insertion of new entries with cache_enter() is
  *	comparatively infrequent, and overshadowed by the cost of expensive
  *	file system metadata operations (which may involve disk I/O).  We
  *	therefore want to make everything simplest in the lookup path.
+ *
  *	struct namecache is mostly stable except for list and tree related
  *	entries, changes to which don't affect the cached name or vnode.
  *	For changes to name+vnode, entries are purged in preference to
  *	modifying them.
+ *
  *	Read access to namecache entries is made via tree, list, or LRU
  *	list.  A lock corresponding to the direction of access should be
  *	held.  See definition of "struct namecache" in src/sys/namei.src,
  *	and the definition of "struct vnode" for the particulars.
+ *
  *	Per-CPU statistics, and LRU list totals are read unlocked, since
  *	an approximate value is OK.  We maintain 32-bit sized per-CPU
  *	counters and 64-bit global counters under the theory that 32-bit
  *	sized counters are less likely to be hosed by nonatomic increment
  *	(on 32-bit platforms).
+ *
  *	The lock order is:
+ *
  *	1) vi->vi_nc_lock	(tree or parent -> child direction,
  *				 used during forward lookup)
+ *
  *	2) vi->vi_nc_listlock	(list or child -> parent direction,
  *				 used during reverse lookup)
+ *
  *	3) cache_lru_lock	(LRU list direction, used during reclaim)
+ *
  *	4) vp->v_interlock	(what the cache entry points to)
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.140 2020/04/22 21:35:52 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.141 2020/04/23 22:58:36 ad Exp $");
 #define __NAMECACHE_PRIVATE
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
 #include "opt_dtrace.h"
 #endif
 #include <sys/types.h>
 #include <sys/atomic.h>
 #include <sys/callout.h>
 #include <sys/cpu.h>
 #include <sys/errno.h>
 #include <sys/evcnt.h>
 #include <sys/hash.h>
 #include <sys/kernel.h>
 #include <sys/mount.h>
 #include <sys/mutex.h>
 #include <sys/namei.h>
 #include <sys/param.h>
 #include <sys/pool.h>
 #include <sys/sdt.h>
 #include <sys/sysctl.h>
 #include <sys/systm.h>
 #include <sys/time.h>
 #include <sys/vnode_impl.h>
 #include <miscfs/genfs/genfs.h>
 static void	cache_activate(struct namecache *);
 static void	cache_update_stats(void *);
 static int	cache_compare_nodes(void *, const void *, const void *);
 static void	cache_deactivate(void);
 static void	cache_reclaim(void);
 static int	cache_stat_sysctl(SYSCTLFN_ARGS);
 /*
  * Global pool cache.
  */
 static pool_cache_t cache_pool __read_mostly;
 /*
  * LRU replacement.
  */
 enum cache_lru_id {
 	LRU_ACTIVE,
 	LRU_INACTIVE,
 	LRU_COUNT
 };
 static struct {
 	TAILQ_HEAD(, namecache)	list[LRU_COUNT];
 	u_int			count[LRU_COUNT];
 } cache_lru __cacheline_aligned;
 static kmutex_t cache_lru_lock __cacheline_aligned;
 /*
  * Cache effectiveness statistics.  nchstats holds system-wide total.
  */
 struct nchstats	nchstats;
 struct nchstats_percpu _NAMEI_CACHE_STATS(uint32_t);
 struct nchcpu {
 	struct nchstats_percpu cur;
 	struct nchstats_percpu last;
 };
 static callout_t cache_stat_callout;
 static kmutex_t cache_stat_lock __cacheline_aligned;
 #define	COUNT(f) do { \
 	lwp_t *l = curlwp; \
 	KPREEMPT_DISABLE(l); \
 	((struct nchstats_percpu *)curcpu()->ci_data.cpu_nch)->f++; \
 	KPREEMPT_ENABLE(l); \
 } while (/* CONSTCOND */ 0);
 #define	UPDATE(nchcpu, f) do { \
 	uint32_t cur = atomic_load_relaxed(&nchcpu->cur.f); \
 	nchstats.f += (uint32_t)(cur - nchcpu->last.f); \
 	nchcpu->last.f = cur; \
 } while (/* CONSTCOND */ 0)
 /*
  * Tunables.  cache_maxlen replaces the historical doingcache:
  * set it zero to disable caching for debugging purposes.
  */
 int cache_lru_maxdeact __read_mostly = 2;	/* max # to deactivate */
 int cache_lru_maxscan __read_mostly = 64;	/* max # to scan/reclaim */
 int cache_maxlen __read_mostly = USHRT_MAX;	/* max name length to cache */
 int cache_stat_interval __read_mostly = 300;	/* in seconds */
 /*
  * sysctl stuff.
  */
 static struct	sysctllog *cache_sysctllog;
 /*
  * Red-black tree stuff.
  */
 static const rb_tree_ops_t cache_rbtree_ops = {
 	.rbto_compare_nodes = cache_compare_nodes,
 	.rbto_compare_key = cache_compare_nodes,
 	.rbto_node_offset = offsetof(struct namecache, nc_tree),
 	.rbto_context = NULL
 };
 /*
  * dtrace probes.
  */
 SDT_PROVIDER_DEFINE(vfs);
 SDT_PROBE_DEFINE1(vfs, namecache, invalidate, done, "struct vnode *");
 SDT_PROBE_DEFINE1(vfs, namecache, purge, parents, "struct vnode *");
 SDT_PROBE_DEFINE1(vfs, namecache, purge, children, "struct vnode *");
 SDT_PROBE_DEFINE2(vfs, namecache, purge, name, "char *", "size_t");
 SDT_PROBE_DEFINE1(vfs, namecache, purge, vfs, "struct mount *");
 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *",
     "char *", "size_t");
 SDT_PROBE_DEFINE3(vfs, namecache, lookup, miss, "struct vnode *",
     "char *", "size_t");
 SDT_PROBE_DEFINE3(vfs, namecache, lookup, toolong, "struct vnode *",
     "char *", "size_t");
 SDT_PROBE_DEFINE2(vfs, namecache, revlookup, success, "struct vnode *",
      "struct vnode *");
 SDT_PROBE_DEFINE2(vfs, namecache, revlookup, fail, "struct vnode *",
      "int");
 SDT_PROBE_DEFINE2(vfs, namecache, prune, done, "int", "int");
 SDT_PROBE_DEFINE3(vfs, namecache, enter, toolong, "struct vnode *",
     "char *", "size_t");
 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *",
     "char *", "size_t");
 /*
  * rbtree: compare two nodes.
  */
 static int
 cache_compare_nodes(void *context, const void *n1, const void *n2)
+{
 	const struct namecache *nc1 = n1;
 	const struct namecache *nc2 = n2;
 	if (nc1->nc_key < nc2->nc_key) {
 		return -1;
+	}
 	if (nc1->nc_key > nc2->nc_key) {
 		return 1;
+	}
 	KASSERT(nc1->nc_nlen == nc2->nc_nlen);
 	return memcmp(nc1->nc_name, nc2->nc_name, nc1->nc_nlen);
+}
 /*
  * Compute a key value for the given name.  The name length is encoded in
  * the key value to try and improve uniqueness, and so that length doesn't
  * need to be compared separately for string comparisons.
  */
 static inline uint64_t
 cache_key(const char *name, size_t nlen)
+{
 	uint64_t key;
 	KASSERT(nlen <= USHRT_MAX);
 	key = hash32_buf(name, nlen, HASH32_STR_INIT);
 	return (key << 32) | nlen;
+}
 /*
  * Remove an entry from the cache.  vi_nc_lock must be held, and if dir2node
  * is true, then we're locking in the conventional direction and the list
  * lock will be acquired when removing the entry from the vnode list.
  */
 static void
 cache_remove(struct namecache *ncp, const bool dir2node)
+{
 	struct vnode *vp, *dvp = ncp->nc_dvp;
 	vnode_impl_t *dvi = VNODE_TO_VIMPL(dvp);
 	KASSERT(rw_write_held(&dvi->vi_nc_lock));
 	KASSERT(cache_key(ncp->nc_name, ncp->nc_nlen) == ncp->nc_key);
 	KASSERT(rb_tree_find_node(&dvi->vi_nc_tree, ncp) == ncp);
 	SDT_PROBE(vfs, namecache, invalidate, done, ncp,
 , 0, 0, 0);
 	/*
 	 * Remove from the vnode's list.  This excludes cache_revlookup(),
 	 * and then it's safe to remove from the LRU lists.
 	 */
 	if ((vp = ncp->nc_vp) != NULL) {
 		vnode_impl_t *vi = VNODE_TO_VIMPL(vp);
 		if (__predict_true(dir2node)) {
 			rw_enter(&vi->vi_nc_listlock, RW_WRITER);
 			TAILQ_REMOVE(&vi->vi_nc_list, ncp, nc_list);
 			rw_exit(&vi->vi_nc_listlock);
 		} else {
 			TAILQ_REMOVE(&vi->vi_nc_list, ncp, nc_list);
+		}
+	}
 	/* Remove from the directory's rbtree. */
 	rb_tree_remove_node(&dvi->vi_nc_tree, ncp);
 	/* Remove from the LRU lists. */
 	mutex_enter(&cache_lru_lock);
 	TAILQ_REMOVE(&cache_lru.list[ncp->nc_lrulist], ncp, nc_lru);
 	cache_lru.count[ncp->nc_lrulist]--;
 	mutex_exit(&cache_lru_lock);
 	/* Finally, free it. */
 	if (ncp->nc_nlen > NCHNAMLEN) {
 		size_t sz = offsetof(struct namecache, nc_name[ncp->nc_nlen]);
 		kmem_free(ncp, sz);
 	} else {
 		pool_cache_put(cache_pool, ncp);
+	}
+}
 /*
  * Find a single cache entry and return it.  vi_nc_lock must be held.
  */
 static struct namecache * __noinline
 cache_lookup_entry(struct vnode *dvp, const char *name, size_t namelen,
     uint64_t key)
+{
 	vnode_impl_t *dvi = VNODE_TO_VIMPL(dvp);
 	struct rb_node *node = dvi->vi_nc_tree.rbt_root;
 	struct namecache *ncp;
 	int lrulist, diff;
 	KASSERT(rw_lock_held(&dvi->vi_nc_lock));
 	/*
 	 * Search the RB tree for the key.  This is an inlined lookup
 	 * tailored for exactly what's needed here (64-bit key and so on)
 	 * that is quite a bit faster than using rb_tree_find_node().
+	 *
 	 * For a matching key memcmp() needs to be called once to confirm
 	 * that the correct name has been found.  Very rarely there will be
 	 * a key value collision and the search will continue.
 	 */
 	for (;;) {
 		if (__predict_false(RB_SENTINEL_P(node))) {
 			return NULL;
+		}
 		ncp = (struct namecache *)node;
 		KASSERT((void *)&ncp->nc_tree == (void *)ncp);
 		KASSERT(ncp->nc_dvp == dvp);
 		if (ncp->nc_key == key) {
 			KASSERT(ncp->nc_nlen == namelen);
 			diff = memcmp(ncp->nc_name, name, namelen);
 			if (__predict_true(diff == 0)) {
 				break;
+			}
 			node = node->rb_nodes[diff < 0];
 		} else {
 			node = node->rb_nodes[ncp->nc_key < key];
+		}
+	}
 	/*
 	 * If the entry is on the wrong LRU list, requeue it.  This is an
 	 * unlocked check, but it will rarely be wrong and even then there
 	 * will be no harm caused.
 	 */
 	lrulist = atomic_load_relaxed(&ncp->nc_lrulist);
 	if (__predict_false(lrulist != LRU_ACTIVE)) {
 		cache_activate(ncp);
+	}
 	return ncp;
+}
 /*
  * Look for a the name in the cache. We don't do this
  * if the segment name is long, simply so the cache can avoid
  * holding long names (which would either waste space, or
  * add greatly to the complexity).
+ *
  * Lookup is called with DVP pointing to the directory to search,
  * and CNP providing the name of the entry being sought: cn_nameptr
  * is the name, cn_namelen is its length, and cn_flags is the flags
  * word from the namei operation.
+ *
  * DVP must be locked.
+ *
  * There are three possible non-error return states:
  *    1. Nothing was found in the cache. Nothing is known about
  *       the requested name.
  *    2. A negative entry was found in the cache, meaning that the
  *       requested name definitely does not exist.
  *    3. A positive entry was found in the cache, meaning that the
  *       requested name does exist and that we are providing the
  *       vnode.
  * In these cases the results are:
  *    1. 0 returned; VN is set to NULL.
  *    2. 1 returned; VN is set to NULL.
  *    3. 1 returned; VN is set to the vnode found.
+ *
  * The additional result argument ISWHT is set to zero, unless a
  * negative entry is found that was entered as a whiteout, in which
  * case ISWHT is set to one.
+ *
  * The ISWHT_RET argument pointer may be null. In this case an
  * assertion is made that the whiteout flag is not set. File systems
  * that do not support whiteouts can/should do this.
+ *
  * Filesystems that do support whiteouts should add ISWHITEOUT to
  * cnp->cn_flags if ISWHT comes back nonzero.
+ *
  * When a vnode is returned, it is locked, as per the vnode lookup
  * locking protocol.
+ *
  * There is no way for this function to fail, in the sense of
  * generating an error that requires aborting the namei operation.
+ *
  * (Prior to October 2012, this function returned an integer status,
  * and a vnode, and mucked with the flags word in CNP for whiteouts.
  * The integer status was -1 for "nothing found", ENOENT for "a
  * negative entry found", 0 for "a positive entry found", and possibly
  * other errors, and the value of VN might or might not have been set
  * depending on what error occurred.)
  */
 bool
 cache_lookup(struct vnode *dvp, const char *name, size_t namelen,
 	     uint32_t nameiop, uint32_t cnflags,
 	     int *iswht_ret, struct vnode **vn_ret)
+{
 	vnode_impl_t *dvi = VNODE_TO_VIMPL(dvp);
 	struct namecache *ncp;
 	struct vnode *vp;
 	uint64_t key;
 	int error;
 	bool hit;
 	krw_t op;
 	/* Establish default result values */
 	if (iswht_ret != NULL) {
 		*iswht_ret = 0;
+	}
 	*vn_ret = NULL;
 	if (__predict_false(namelen > cache_maxlen)) {
 		SDT_PROBE(vfs, namecache, lookup, toolong, dvp,
 		    name, namelen, 0, 0);
 		COUNT(ncs_long);
 		return false;
+	}
 	/* Compute the key up front - don't need the lock. */
 	key = cache_key(name, namelen);
 	/* Could the entry be purged below? */
 	if ((cnflags & ISLASTCN) != 0 &&
 	    ((cnflags & MAKEENTRY) == 0 || nameiop == CREATE)) {
 	    	op = RW_WRITER;
 	} else {
 		op = RW_READER;
+	}
 	/* Now look for the name. */
 	rw_enter(&dvi->vi_nc_lock, op);
 	ncp = cache_lookup_entry(dvp, name, namelen, key);
 	if (__predict_false(ncp == NULL)) {
 		rw_exit(&dvi->vi_nc_lock);
 		COUNT(ncs_miss);
 		SDT_PROBE(vfs, namecache, lookup, miss, dvp,
 		    name, namelen, 0, 0);
 		return false;
+	}
 	if (__predict_false((cnflags & MAKEENTRY) == 0)) {
 		/*
 		 * Last component and we are renaming or deleting,
 		 * the cache entry is invalid, or otherwise don't
 		 * want cache entry to exist.
 		 */
 		KASSERT((cnflags & ISLASTCN) != 0);
 		cache_remove(ncp, true);
 		rw_exit(&dvi->vi_nc_lock);
 		COUNT(ncs_badhits);
 		return false;
+	}
 	if (ncp->nc_vp == NULL) {
 		if (iswht_ret != NULL) {
 			/*
 			 * Restore the ISWHITEOUT flag saved earlier.
 			 */
 			*iswht_ret = ncp->nc_whiteout;
 		} else {
 			KASSERT(!ncp->nc_whiteout);
+		}
 		if (nameiop == CREATE && (cnflags & ISLASTCN) != 0) {
 			/*
 			 * Last component and we are preparing to create
 			 * the named object, so flush the negative cache
 			 * entry.
 			 */
 			COUNT(ncs_badhits);
 			cache_remove(ncp, true);
 			hit = false;
 		} else {
 			COUNT(ncs_neghits);
 			SDT_PROBE(vfs, namecache, lookup, hit, dvp, name,
 			    namelen, 0, 0);
 			/* found neg entry; vn is already null from above */
 			hit = true;
+		}
 		rw_exit(&dvi->vi_nc_lock);
 		return hit;
+	}
 	vp = ncp->nc_vp;
 	mutex_enter(vp->v_interlock);
 	rw_exit(&dvi->vi_nc_lock);
 	/*
 	 * Unlocked except for the vnode interlock.  Call vcache_tryvget().
 	 */
 	error = vcache_tryvget(vp);
 	if (error) {
 		KASSERT(error == EBUSY);
 		/*
 		 * This vnode is being cleaned out.
 		 * XXX badhits?
 		 */
 		COUNT(ncs_falsehits);
 		return false;
+	}
 	COUNT(ncs_goodhits);
 	SDT_PROBE(vfs, namecache, lookup, hit, dvp, name, namelen, 0, 0);
 	/* found it */
 	*vn_ret = vp;
 	return true;
+}
 /*
  * Version of the above without the nameiop argument, for NFS.
  */
 bool
 cache_lookup_raw(struct vnode *dvp, const char *name, size_t namelen,
 		 uint32_t cnflags,
 		 int *iswht_ret, struct vnode **vn_ret)
+{
 	return cache_lookup(dvp, name, namelen, LOOKUP, cnflags | MAKEENTRY,
 	    iswht_ret, vn_ret);
+}
 /*
  * Used by namei() to walk down a path, component by component by looking up
  * names in the cache.  The node locks are chained along the way: a parent's
  * lock is not dropped until the child's is acquired.
  */
 bool
 cache_lookup_linked(struct vnode *dvp, const char *name, size_t namelen,
 		    struct vnode **vn_ret, krwlock_t **plock,
 		    kauth_cred_t cred)
+{
 	vnode_impl_t *dvi = VNODE_TO_VIMPL(dvp);
 	struct namecache *ncp;
 	uint64_t key;
 	int error;
 	/* Establish default results. */
 	*vn_ret = NULL;
 	/* If disabled, or file system doesn't support this, bail out. */
 	if (__predict_false((dvp->v_mount->mnt_iflag & IMNT_NCLOOKUP) == 0)) {
 		return false;
+	}
 	if (__predict_false(namelen > cache_maxlen)) {
 		COUNT(ncs_long);
 		return false;
+	}
 	/* Compute the key up front - don't need the lock. */
 	key = cache_key(name, namelen);
 	/*
 	 * Acquire the directory lock.  Once we have that, we can drop the
 	 * previous one (if any).
+	 *
 	 * The two lock holds mean that the directory can't go away while
 	 * here: the directory must be purged with cache_purge() before
 	 * being freed, and both parent & child's vi_nc_lock must be taken
 	 * before that point is passed.
+	 *
 	 * However if there's no previous lock, like at the root of the
 	 * chain, then "dvp" must be referenced to prevent dvp going away
 	 * before we get its lock.
+	 *
 	 * Note that the two locks can be the same if looking up a dot, for
 	 * example: /usr/bin/.  If looking up the parent (..) we can't wait
 	 * on the lock as child -> parent is the wrong direction.
 	 */
 	if (*plock != &dvi->vi_nc_lock) {
-		if (namelen == 2 && name[0] == '.' && name[1] == '.') {
+		if (!rw_tryenter(&dvi->vi_nc_lock, RW_READER)) {
-			if (!rw_tryenter(&dvi->vi_nc_lock, RW_READER)) {
+			return false;
 				return false;
 		} else {
 			rw_enter(&dvi->vi_nc_lock, RW_READER);
+		}
 		if (*plock != NULL) {
 			rw_exit(*plock);
+		}
 		*plock = &dvi->vi_nc_lock;
 	} else if (*plock == NULL) {
 		KASSERT(vrefcnt(dvp) > 0);
+	}
 	/*
 	 * First up check if the user is allowed to look up files in this
 	 * directory.
 	 */
 	KASSERT(dvi->vi_nc_mode != VNOVAL && dvi->vi_nc_uid != VNOVAL &&
 	    dvi->vi_nc_gid != VNOVAL);
 	error = kauth_authorize_vnode(cred, KAUTH_ACCESS_ACTION(VEXEC,
 	    dvp->v_type, dvi->vi_nc_mode & ALLPERMS), dvp, NULL,
 	    genfs_can_access(dvp->v_type, dvi->vi_nc_mode & ALLPERMS,
 	    dvi->vi_nc_uid, dvi->vi_nc_gid, VEXEC, cred));
 	if (error != 0) {
 		COUNT(ncs_denied);
 		return false;
+	}
 	/*
 	 * Now look for a matching cache entry.
 	 */
 	ncp = cache_lookup_entry(dvp, name, namelen, key);
 	if (__predict_false(ncp == NULL)) {
 		COUNT(ncs_miss);
 		SDT_PROBE(vfs, namecache, lookup, miss, dvp,
 		    name, namelen, 0, 0);
 		return false;
+	}
 	if (ncp->nc_vp == NULL) {
 		/* found negative entry; vn is already null from above */
 		COUNT(ncs_neghits);
 		SDT_PROBE(vfs, namecache, lookup, hit, dvp, name, namelen, 0, 0);
 		return true;
+	}
 	COUNT(ncs_goodhits); /* XXX can be "badhits" */
 	SDT_PROBE(vfs, namecache, lookup, hit, dvp, name, namelen, 0, 0);
 	/*
 	 * Return with the directory lock still held.  It will either be
 	 * returned to us with another call to cache_lookup_linked() when
 	 * looking up the next component, or the caller will release it
 	 * manually when finished.
 	 */
 	*vn_ret = ncp->nc_vp;
 	return true;
+}
 /*
  * Scan cache looking for name of directory entry pointing at vp.
  * Will not search for "." or "..".
+ *
  * If the lookup succeeds the vnode is referenced and stored in dvpp.
+ *
  * If bufp is non-NULL, also place the name in the buffer which starts
  * at bufp, immediately before *bpp, and move bpp backwards to point
  * at the start of it.  (Yes, this is a little baroque, but it's done
  * this way to cater to the whims of getcwd).
+ *
  * Returns 0 on success, -1 on cache miss, positive errno on failure.
  */
 int
 cache_revlookup(struct vnode *vp, struct vnode **dvpp, char **bpp, char *bufp,
     bool checkaccess, int perms)
+{
 	vnode_impl_t *vi = VNODE_TO_VIMPL(vp);
 	struct namecache *ncp;
 	struct vnode *dvp;
 	int error, nlen, lrulist;
 	char *bp;
 	KASSERT(vp != NULL);
 	if (cache_maxlen == 0)
 		goto out;
 	rw_enter(&vi->vi_nc_listlock, RW_READER);
 	if (checkaccess) {
 		/*
 		 * Check if the user is allowed to see.  NOTE: this is
 		 * checking for access on the "wrong" directory.  getcwd()
 		 * wants to see that there is access on every component
 		 * along the way, not that there is access to any individual
 		 * component.  Don't use this to check you can look in vp.
+		 *
 		 * I don't like it, I didn't come up with it, don't blame me!
 		 */
 		KASSERT(vi->vi_nc_mode != VNOVAL && vi->vi_nc_uid != VNOVAL &&
 		    vi->vi_nc_gid != VNOVAL);
 		error = kauth_authorize_vnode(curlwp->l_cred,
 		    KAUTH_ACCESS_ACTION(VEXEC, vp->v_type, vi->vi_nc_mode &
 		    ALLPERMS), vp, NULL, genfs_can_access(vp->v_type,
 		    vi->vi_nc_mode & ALLPERMS, vi->vi_nc_uid, vi->vi_nc_gid,
 		    perms, curlwp->l_cred));
 		    if (error != 0) {
 		    	rw_exit(&vi->vi_nc_listlock);
 			COUNT(ncs_denied);
 			return EACCES;
+		}
+	}
 	TAILQ_FOREACH(ncp, &vi->vi_nc_list, nc_list) {
 		KASSERT(ncp->nc_vp == vp);
 		KASSERT(ncp->nc_dvp != NULL);
 		nlen = ncp->nc_nlen;
 		/*
 		 * The queue is partially sorted.  Once we hit dots, nothing
 		 * else remains but dots and dotdots, so bail out.
 		 */
 		if (ncp->nc_name[0] == '.') {
 			if (nlen == 1 ||
 			    (nlen == 2 && ncp->nc_name[1] == '.')) {
 			    	break;
+			}
+		}
 		/*
 		 * Record a hit on the entry.  This is an unlocked read but
 		 * even if wrong it doesn't matter too much.
 		 */
 		lrulist = atomic_load_relaxed(&ncp->nc_lrulist);
 		if (lrulist != LRU_ACTIVE) {
 			cache_activate(ncp);
+		}
 		if (bufp) {
 			bp = *bpp;
 			bp -= nlen;
 			if (bp <= bufp) {
 				*dvpp = NULL;
 				rw_exit(&vi->vi_nc_listlock);
 				SDT_PROBE(vfs, namecache, revlookup,
 				    fail, vp, ERANGE, 0, 0, 0);
 				return (ERANGE);
+			}
 			memcpy(bp, ncp->nc_name, nlen);
 			*bpp = bp;
+		}
 		dvp = ncp->nc_dvp;
 		mutex_enter(dvp->v_interlock);
 		rw_exit(&vi->vi_nc_listlock);
 		error = vcache_tryvget(dvp);
 		if (error) {
 			KASSERT(error == EBUSY);
 			if (bufp)
 				(*bpp) += nlen;
 			*dvpp = NULL;
 			SDT_PROBE(vfs, namecache, revlookup, fail, vp,
 			    error, 0, 0, 0);
 			return -1;
+		}
 		*dvpp = dvp;
 		SDT_PROBE(vfs, namecache, revlookup, success, vp, dvp,
 , 0, 0);
 		COUNT(ncs_revhits);
 		return (0);
+	}
 	rw_exit(&vi->vi_nc_listlock);
 	COUNT(ncs_revmiss);
  out:
 	*dvpp = NULL;
 	return (-1);
+}
 /*
  * Add an entry to the cache.
  */
 void
 cache_enter(struct vnode *dvp, struct vnode *vp,
 	    const char *name, size_t namelen, uint32_t cnflags)
+{
 	vnode_impl_t *dvi = VNODE_TO_VIMPL(dvp);
 	struct namecache *ncp, *oncp;
 	int total;
 	/* First, check whether we can/should add a cache entry. */
 	if ((cnflags & MAKEENTRY) == 0 ||
 	    __predict_false(namelen > cache_maxlen)) {
 		SDT_PROBE(vfs, namecache, enter, toolong, vp, name, namelen,
 , 0);
 		return;
+	}
 	SDT_PROBE(vfs, namecache, enter, done, vp, name, namelen, 0, 0);
 	/*
 	 * Reclaim some entries if over budget.  This is an unlocked check,
 	 * but it doesn't matter.  Just need to catch up with things
 	 * eventually: it doesn't matter if we go over temporarily.
 	 */
 	total = atomic_load_relaxed(&cache_lru.count[LRU_ACTIVE]);
 	total += atomic_load_relaxed(&cache_lru.count[LRU_INACTIVE]);
 	if (__predict_false(total > desiredvnodes)) {
 		cache_reclaim();
+	}
 	/* Now allocate a fresh entry. */
 	if (__predict_true(namelen <= NCHNAMLEN)) {
 		ncp = pool_cache_get(cache_pool, PR_WAITOK);
 	} else {
 		size_t sz = offsetof(struct namecache, nc_name[namelen]);
 		ncp = kmem_alloc(sz, KM_SLEEP);
+	}
 	/*
 	 * Fill in cache info.  For negative hits, save the ISWHITEOUT flag
 	 * so we can restore it later when the cache entry is used again.
 	 */
 	ncp->nc_vp = vp;
 	ncp->nc_dvp = dvp;
 	ncp->nc_key = cache_key(name, namelen);
 	ncp->nc_nlen = namelen;
 	ncp->nc_whiteout = ((cnflags & ISWHITEOUT) != 0);
 	memcpy(ncp->nc_name, name, namelen);
 	/*
 	 * Insert to the directory.  Concurrent lookups may race for a cache
 	 * entry.  If there's a entry there already, purge it.
 	 */
 	rw_enter(&dvi->vi_nc_lock, RW_WRITER);
 	oncp = rb_tree_insert_node(&dvi->vi_nc_tree, ncp);
 	if (oncp != ncp) {
 		KASSERT(oncp->nc_key == ncp->nc_key);
 		KASSERT(oncp->nc_nlen == ncp->nc_nlen);
 		KASSERT(memcmp(oncp->nc_name, name, namelen) == 0);
 		cache_remove(oncp, true);
 		oncp = rb_tree_insert_node(&dvi->vi_nc_tree, ncp);
 		KASSERT(oncp == ncp);
+	}
 	/*
 	 * With the directory lock still held, insert to the tail of the
 	 * ACTIVE LRU list (new) and take the opportunity to incrementally
 	 * balance the lists.
 	 */
 	mutex_enter(&cache_lru_lock);
 	ncp->nc_lrulist = LRU_ACTIVE;
 	cache_lru.count[LRU_ACTIVE]++;
 	TAILQ_INSERT_TAIL(&cache_lru.list[LRU_ACTIVE], ncp, nc_lru);
 	cache_deactivate();
 	mutex_exit(&cache_lru_lock);
 	/*
 	 * Finally, insert to the vnode and unlock.  With everything set up
 	 * it's safe to let cache_revlookup() see the entry.  Partially sort
 	 * the per-vnode list: dots go to back so cache_revlookup() doesn't
 	 * have to consider them.
 	 */
 	if (vp != NULL) {
 		vnode_impl_t *vi = VNODE_TO_VIMPL(vp);
 		rw_enter(&vi->vi_nc_listlock, RW_WRITER);
 		if ((namelen == 1 && name[0] == '.') ||
 		    (namelen == 2 && name[0] == '.' && name[1] == '.')) {
 			TAILQ_INSERT_TAIL(&vi->vi_nc_list, ncp, nc_list);
 		} else {
 			TAILQ_INSERT_HEAD(&vi->vi_nc_list, ncp, nc_list);
+		}
 		rw_exit(&vi->vi_nc_listlock);
+	}
 	rw_exit(&dvi->vi_nc_lock);
+}
 /*
  * Set identity info in cache for a vnode.  We only care about directories
  * so ignore other updates.
  */
 void
 cache_enter_id(struct vnode *vp, mode_t mode, uid_t uid, gid_t gid)
+{
 	vnode_impl_t *vi = VNODE_TO_VIMPL(vp);
 	if (vp->v_type == VDIR) {
 		/* Grab both locks, for forward & reverse lookup. */
 		rw_enter(&vi->vi_nc_lock, RW_WRITER);
 		rw_enter(&vi->vi_nc_listlock, RW_WRITER);
 		vi->vi_nc_mode = mode;
 		vi->vi_nc_uid = uid;
 		vi->vi_nc_gid = gid;
 		rw_exit(&vi->vi_nc_listlock);
 		rw_exit(&vi->vi_nc_lock);
+	}
+}
 /*
  * Return true if we have identity for the given vnode, and use as an
  * opportunity to confirm that everything squares up.
+ *
  * Because of shared code, some file systems could provide partial
  * information, missing some updates, so always check the mount flag
  * instead of looking for !VNOVAL.
  */
 bool
 cache_have_id(struct vnode *vp)
+{
 	if (vp->v_type == VDIR &&
 	    (vp->v_mount->mnt_iflag & IMNT_NCLOOKUP) != 0) {
 		KASSERT(VNODE_TO_VIMPL(vp)->vi_nc_mode != VNOVAL);
 		KASSERT(VNODE_TO_VIMPL(vp)->vi_nc_uid != VNOVAL);
 		KASSERT(VNODE_TO_VIMPL(vp)->vi_nc_gid != VNOVAL);
 		return true;
 	} else {
 		return false;
+	}
+}
 /*
  * Name cache initialization, from vfs_init() when the system is booting.
  */
 void
 nchinit(void)
+{
 	cache_pool = pool_cache_init(sizeof(struct namecache),
 	    coherency_unit, 0, 0, "namecache", NULL, IPL_NONE, NULL,
 	    NULL, NULL);
 	KASSERT(cache_pool != NULL);
 	mutex_init(&cache_lru_lock, MUTEX_DEFAULT, IPL_NONE);
 	TAILQ_INIT(&cache_lru.list[LRU_ACTIVE]);
 	TAILQ_INIT(&cache_lru.list[LRU_INACTIVE]);
 	mutex_init(&cache_stat_lock, MUTEX_DEFAULT, IPL_NONE);
 	callout_init(&cache_stat_callout, CALLOUT_MPSAFE);
 	callout_setfunc(&cache_stat_callout, cache_update_stats, NULL);
 	callout_schedule(&cache_stat_callout, cache_stat_interval * hz);
 	KASSERT(cache_sysctllog == NULL);
 	sysctl_createv(&cache_sysctllog, 0, NULL, NULL,
 		       CTLFLAG_PERMANENT,
 		       CTLTYPE_STRUCT, "namecache_stats",
 		       SYSCTL_DESCR("namecache statistics"),
 		       cache_stat_sysctl, 0, NULL, 0,
 		       CTL_VFS, CTL_CREATE, CTL_EOL);
+}
 /*
  * Called once for each CPU in the system as attached.
  */
 void
 cache_cpu_init(struct cpu_info *ci)
+{
 	void *p;
 	size_t sz;
 	sz = roundup2(sizeof(struct nchstats_percpu), coherency_unit) +
 	    coherency_unit;
 	p = kmem_zalloc(sz, KM_SLEEP);
 	ci->ci_data.cpu_nch = (void *)roundup2((uintptr_t)p, coherency_unit);
+}
 /*
  * A vnode is being allocated: set up cache structures.
  */
 void
 cache_vnode_init(struct vnode *vp)
+{
 	vnode_impl_t *vi = VNODE_TO_VIMPL(vp);
 	rw_init(&vi->vi_nc_lock);
 	rw_init(&vi->vi_nc_listlock);
 	rb_tree_init(&vi->vi_nc_tree, &cache_rbtree_ops);
 	TAILQ_INIT(&vi->vi_nc_list);
 	vi->vi_nc_mode = VNOVAL;
 	vi->vi_nc_uid = VNOVAL;
 	vi->vi_nc_gid = VNOVAL;
+}
 /*
  * A vnode is being freed: finish cache structures.
  */
 void
 cache_vnode_fini(struct vnode *vp)
+{
 	vnode_impl_t *vi = VNODE_TO_VIMPL(vp);
 	KASSERT(RB_TREE_MIN(&vi->vi_nc_tree) == NULL);
 	KASSERT(TAILQ_EMPTY(&vi->vi_nc_list));
 	rw_destroy(&vi->vi_nc_lock);
 	rw_destroy(&vi->vi_nc_listlock);
+}
 /*
  * Helper for cache_purge1(): purge cache entries for the given vnode from
  * all directories that the vnode is cached in.
  */
 static void
 cache_purge_parents(struct vnode *vp)
+{
 	vnode_impl_t *dvi, *vi = VNODE_TO_VIMPL(vp);
 	struct vnode *dvp, *blocked;
 	struct namecache *ncp;
 	SDT_PROBE(vfs, namecache, purge, parents, vp, 0, 0, 0, 0);
 	blocked = NULL;
 	rw_enter(&vi->vi_nc_listlock, RW_WRITER);
 	while ((ncp = TAILQ_FIRST(&vi->vi_nc_list)) != NULL) {
 		/*
 		 * Locking in the wrong direction.  Try for a hold on the
 		 * directory node's lock, and if we get it then all good,
 		 * nuke the entry and move on to the next.
 		 */
 		dvp = ncp->nc_dvp;
 		dvi = VNODE_TO_VIMPL(dvp);
 		if (rw_tryenter(&dvi->vi_nc_lock, RW_WRITER)) {
 			cache_remove(ncp, false);
 			rw_exit(&dvi->vi_nc_lock);
 			blocked = NULL;
 			continue;
+		}
 		/*
 		 * We can't wait on the directory node's lock with our list
 		 * lock held or the system could deadlock.
+		 *
 		 * Take a hold on the directory vnode to prevent it from
 		 * being freed (taking the vnode & lock with it).  Then
 		 * wait for the lock to become available with no other locks
 		 * held, and retry.
+		 *
 		 * If this happens twice in a row, give the other side a
 		 * breather; we can do nothing until it lets go.
 		 */
 		vhold(dvp);
 		rw_exit(&vi->vi_nc_listlock);
 		rw_enter(&dvi->vi_nc_lock, RW_WRITER);
 		/* Do nothing. */
 		rw_exit(&dvi->vi_nc_lock);
 		holdrele(dvp);
 		if (blocked == dvp) {
 			kpause("ncpurge", false, 1, NULL);
+		}
 		rw_enter(&vi->vi_nc_listlock, RW_WRITER);
 		blocked = dvp;
+	}
 	rw_exit(&vi->vi_nc_listlock);
+}
 /*
  * Helper for cache_purge1(): purge all cache entries hanging off the given
  * directory vnode.
  */
 static void
 cache_purge_children(struct vnode *dvp)
+{
 	vnode_impl_t *dvi = VNODE_TO_VIMPL(dvp);
 	struct namecache *ncp;
 	SDT_PROBE(vfs, namecache, purge, children, dvp, 0, 0, 0, 0);
 	rw_enter(&dvi->vi_nc_lock, RW_WRITER);
 	while ((ncp = RB_TREE_MIN(&dvi->vi_nc_tree)) != NULL) {
 		cache_remove(ncp, true);
+	}
 	rw_exit(&dvi->vi_nc_lock);
+}
 /*
  * Helper for cache_purge1(): purge cache entry from the given vnode,
  * finding it by name.
  */
 static void
 cache_purge_name(struct vnode *dvp, const char *name, size_t namelen)
+{
 	vnode_impl_t *dvi = VNODE_TO_VIMPL(dvp);
 	struct namecache *ncp;
 	uint64_t key;
 	SDT_PROBE(vfs, namecache, purge, name, name, namelen, 0, 0, 0);
 	key = cache_key(name, namelen);
 	rw_enter(&dvi->vi_nc_lock, RW_WRITER);
 	ncp = cache_lookup_entry(dvp, name, namelen, key);
 	if (ncp) {
 		cache_remove(ncp, true);
+	}
 	rw_exit(&dvi->vi_nc_lock);
+}
 /*
  * Cache flush, a particular vnode; called when a vnode is renamed to
  * hide entries that would now be invalid.
  */
 void
 cache_purge1(struct vnode *vp, const char *name, size_t namelen, int flags)
+{
 	if (flags & PURGE_PARENTS) {
 		cache_purge_parents(vp);
+	}
 	if (flags & PURGE_CHILDREN) {
 		cache_purge_children(vp);
+	}
 	if (name != NULL) {
 		cache_purge_name(vp, name, namelen);
+	}
+}
 /*
  * vnode filter for cache_purgevfs().
  */
 static bool
 cache_vdir_filter(void *cookie, vnode_t *vp)
+{
 	return vp->v_type == VDIR;
+}
 /*
  * Cache flush, a whole filesystem; called when filesys is umounted to
  * remove entries that would now be invalid.
  */
 void
 cache_purgevfs(struct mount *mp)
+{
 	struct vnode_iterator *iter;
 	vnode_t *dvp;
 	vfs_vnode_iterator_init(mp, &iter);
 	for (;;) {
 		dvp = vfs_vnode_iterator_next(iter, cache_vdir_filter, NULL);
 		if (dvp == NULL) {
 			break;
+		}
 		cache_purge_children(dvp);
 		vrele(dvp);
+	}
 	vfs_vnode_iterator_destroy(iter);
+}
 /*
  * Re-queue an entry onto the tail of the active LRU list, after it has
  * scored a hit.
  */
 static void
 cache_activate(struct namecache *ncp)
+{
 	mutex_enter(&cache_lru_lock);
 	TAILQ_REMOVE(&cache_lru.list[ncp->nc_lrulist], ncp, nc_lru);
 	TAILQ_INSERT_TAIL(&cache_lru.list[LRU_ACTIVE], ncp, nc_lru);
 	cache_lru.count[ncp->nc_lrulist]--;
 	cache_lru.count[LRU_ACTIVE]++;
 	ncp->nc_lrulist = LRU_ACTIVE;
 	mutex_exit(&cache_lru_lock);
+}
 /*
  * Try to balance the LRU lists.  Pick some victim entries, and re-queue
  * them from the head of the active list to the tail of the inactive list.
  */
 static void
 cache_deactivate(void)
+{
 	struct namecache *ncp;
 	int total, i;
 	KASSERT(mutex_owned(&cache_lru_lock));
 	/* If we're nowhere near budget yet, don't bother. */
 	total = cache_lru.count[LRU_ACTIVE] + cache_lru.count[LRU_INACTIVE];
 	if (total < (desiredvnodes >> 1)) {
 	    	return;
+	}
 	/*
 	 * Aim for a 1:1 ratio of active to inactive.  This is to allow each
 	 * potential victim a reasonable amount of time to cycle through the
 	 * inactive list in order to score a hit and be reactivated, while
 	 * trying not to cause reactivations too frequently.
 	 */
 	if (cache_lru.count[LRU_ACTIVE] < cache_lru.count[LRU_INACTIVE]) {
 		return;
+	}
 	/* Move only a few at a time; will catch up eventually. */
 	for (i = 0; i < cache_lru_maxdeact; i++) {
 		ncp = TAILQ_FIRST(&cache_lru.list[LRU_ACTIVE]);
 		if (ncp == NULL) {
 			break;
+		}
 		KASSERT(ncp->nc_lrulist == LRU_ACTIVE);
 		ncp->nc_lrulist = LRU_INACTIVE;
 		TAILQ_REMOVE(&cache_lru.list[LRU_ACTIVE], ncp, nc_lru);
 		TAILQ_INSERT_TAIL(&cache_lru.list[LRU_INACTIVE], ncp, nc_lru);
 		cache_lru.count[LRU_ACTIVE]--;
 		cache_lru.count[LRU_INACTIVE]++;
+	}
+}
 /*
  * Free some entries from the cache, when we have gone over budget.
+ *
  * We don't want to cause too much work for any individual caller, and it
  * doesn't matter if we temporarily go over budget.  This is also "just a
  * cache" so it's not a big deal if we screw up and throw out something we
  * shouldn't.  So we take a relaxed attitude to this process to reduce its
  * impact.
  */
 static void
 cache_reclaim(void)
+{
 	struct namecache *ncp;
 	vnode_impl_t *dvi;
 	int toscan;
 	/*
 	 * Scan up to a preset maxium number of entries, but no more than
 	 * 0.8% of the total at once (to allow for very small systems).
+	 *
 	 * On bigger systems, do a larger chunk of work to reduce the number
 	 * of times that cache_lru_lock is held for any length of time.
 	 */
 	mutex_enter(&cache_lru_lock);
 	toscan = MIN(cache_lru_maxscan, desiredvnodes >> 7);
 	toscan = MAX(toscan, 1);
 	SDT_PROBE(vfs, namecache, prune, done, cache_lru.count[LRU_ACTIVE] +
 	    cache_lru.count[LRU_INACTIVE], toscan, 0, 0, 0);
 	while (toscan-- != 0) {
 		/* First try to balance the lists. */
 		cache_deactivate();
 		/* Now look for a victim on head of inactive list (old). */
 		ncp = TAILQ_FIRST(&cache_lru.list[LRU_INACTIVE]);
 		if (ncp == NULL) {
 			break;
+		}
 		dvi = VNODE_TO_VIMPL(ncp->nc_dvp);
 		KASSERT(ncp->nc_lrulist == LRU_INACTIVE);
 		KASSERT(dvi != NULL);
 		/*
 		 * Locking in the wrong direction.  If we can't get the
 		 * lock, the directory is actively busy, and it could also
 		 * cause problems for the next guy in here, so send the
 		 * entry to the back of the list.
 		 */
 		if (!rw_tryenter(&dvi->vi_nc_lock, RW_WRITER)) {
 			TAILQ_REMOVE(&cache_lru.list[LRU_INACTIVE],
 			    ncp, nc_lru);
 			TAILQ_INSERT_TAIL(&cache_lru.list[LRU_INACTIVE],
 			    ncp, nc_lru);
 			continue;
+		}
 		/*
 		 * Now have the victim entry locked.  Drop the LRU list
 		 * lock, purge the entry, and start over.  The hold on
 		 * vi_nc_lock will prevent the vnode from vanishing until
 		 * finished (cache_purge() will be called on dvp before it
 		 * disappears, and that will wait on vi_nc_lock).
 		 */
 		mutex_exit(&cache_lru_lock);
 		cache_remove(ncp, true);
 		rw_exit(&dvi->vi_nc_lock);
 		mutex_enter(&cache_lru_lock);
+	}
 	mutex_exit(&cache_lru_lock);
+}
 /*
  * For file system code: count a lookup that required a full re-scan of
  * directory metadata.
  */
 void
 namecache_count_pass2(void)
+{
 	COUNT(ncs_pass2);
+}
 /*
  * For file system code: count a lookup that scored a hit in the directory
  * metadata near the location of the last lookup.
  */
 void
 namecache_count_2passes(void)
+{
 	COUNT(ncs_2passes);
+}
 /*
  * Sum the stats from all CPUs into nchstats.  This needs to run at least
  * once within every window where a 32-bit counter could roll over.  It's
  * called regularly by timer to ensure this.
  */
 static void
 cache_update_stats(void *cookie)
+{
 	CPU_INFO_ITERATOR cii;
 	struct cpu_info *ci;
 	mutex_enter(&cache_stat_lock);
 	for (CPU_INFO_FOREACH(cii, ci)) {
 		struct nchcpu *nchcpu = ci->ci_data.cpu_nch;
 		UPDATE(nchcpu, ncs_goodhits);
 		UPDATE(nchcpu, ncs_neghits);
 		UPDATE(nchcpu, ncs_badhits);
 		UPDATE(nchcpu, ncs_falsehits);
 		UPDATE(nchcpu, ncs_miss);
 		UPDATE(nchcpu, ncs_long);
 		UPDATE(nchcpu, ncs_pass2);
 		UPDATE(nchcpu, ncs_2passes);
 		UPDATE(nchcpu, ncs_revhits);
 		UPDATE(nchcpu, ncs_revmiss);
 		UPDATE(nchcpu, ncs_denied);
+	}
 	if (cookie != NULL) {
 		memcpy(cookie, &nchstats, sizeof(nchstats));
+	}
 	/* Reset the timer; arrive back here in N minutes at latest. */
 	callout_schedule(&cache_stat_callout, cache_stat_interval * hz);
 	mutex_exit(&cache_stat_lock);
+}
 /*
  * Fetch the current values of the stats for sysctl.
  */
 static int
 cache_stat_sysctl(SYSCTLFN_ARGS)
+{
 	struct nchstats stats;
 	if (oldp == NULL) {
 		*oldlenp = sizeof(nchstats);
 		return 0;
+	}
 	if (*oldlenp <= 0) {
 		*oldlenp = 0;
 		return 0;
+	}
 	/* Refresh the global stats. */
 	sysctl_unlock();
 	cache_update_stats(&stats);
 	sysctl_relock();
 	*oldlenp = MIN(sizeof(stats), *oldlenp);
 	return sysctl_copyout(l, &stats, oldp, *oldlenp);
+}
 /*
  * For the debugger, given the address of a vnode, print all associated
  * names in the cache.
  */
 #ifdef DDB
 void
 namecache_print(struct vnode *vp, void (*pr)(const char *, ...))
+{
 	struct vnode *dvp = NULL;
 	struct namecache *ncp;
 	enum cache_lru_id id;
 	for (id = 0; id < LRU_COUNT; id++) {
 		TAILQ_FOREACH(ncp, &cache_lru.list[id], nc_lru) {
 			if (ncp->nc_vp == vp) {
 				(*pr)("name %.*s\n", ncp->nc_nlen,
 				    ncp->nc_name);
 				dvp = ncp->nc_dvp;
+			}
+		}
+	}
 	if (dvp == NULL) {
 		(*pr)("name not found\n");
 		return;
+	}
 	for (id = 0; id < LRU_COUNT; id++) {
 		TAILQ_FOREACH(ncp, &cache_lru.list[id], nc_lru) {
 			if (ncp->nc_vp == dvp) {
 				(*pr)("parent %.*s\n", ncp->nc_nlen,
 				    ncp->nc_name);
+			}
+		}
+	}
+}
 #endif