 @@ -1,2186 +1,2223 @@
-/*	$NetBSD: vfs_bio.c,v 1.297 2020/07/31 04:07:30 chs Exp $	*/
+/*	$NetBSD: vfs_bio.c,v 1.298 2021/04/01 06:25:59 simonb Exp $	*/
 /*-
  * Copyright (c) 2007, 2008, 2009, 2019, 2020 The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Andrew Doran, and by Wasabi Systems, Inc.
+ *
  * 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) 1982, 1986, 1989, 1993
  *	The Regents of the University of California.  All rights reserved.
  * (c) UNIX System Laboratories, Inc.
  * All or some portions of this file are derived from material licensed
  * to the University of California by American Telephone and Telegraph
  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  * the permission of UNIX System Laboratories, Inc.
+ *
  * 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_bio.c	8.6 (Berkeley) 1/11/94
  */
 /*-
  * Copyright (c) 1994 Christopher G. Demetriou
+ *
  * 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. All advertising materials mentioning features or use of this software
  *    must display the following acknowledgement:
  *	This product includes software developed by the University of
  *	California, Berkeley and its contributors.
  * 4. 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_bio.c	8.6 (Berkeley) 1/11/94
  */
 /*
  * The buffer cache subsystem.
+ *
  * Some references:
  *	Bach: The Design of the UNIX Operating System (Prentice Hall, 1986)
  *	Leffler, et al.: The Design and Implementation of the 4.3BSD
  *		UNIX Operating System (Addison Welley, 1989)
+ *
  * Locking
+ *
  * There are three locks:
  * - bufcache_lock: protects global buffer cache state.
  * - BC_BUSY: a long term per-buffer lock.
  * - buf_t::b_objlock: lock on completion (biowait vs biodone).
+ *
  * For buffers associated with vnodes (a most common case) b_objlock points
  * to the vnode_t::v_interlock.  Otherwise, it points to generic buffer_lock.
+ *
  * Lock order:
  *	bufcache_lock ->
  *		buf_t::b_objlock
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.297 2020/07/31 04:07:30 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.298 2021/04/01 06:25:59 simonb Exp $");
 #ifdef _KERNEL_OPT
 #include "opt_bufcache.h"
 #include "opt_dtrace.h"
 #include "opt_biohist.h"
 #endif
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/proc.h>
 #include <sys/buf.h>
 #include <sys/vnode.h>
 #include <sys/mount.h>
 #include <sys/resourcevar.h>
 #include <sys/sysctl.h>
 #include <sys/conf.h>
 #include <sys/kauth.h>
 #include <sys/fstrans.h>
 #include <sys/intr.h>
 #include <sys/cpu.h>
 #include <sys/wapbl.h>
 #include <sys/bitops.h>
 #include <sys/cprng.h>
 #include <sys/sdt.h>
 #include <uvm/uvm.h>	/* extern struct uvm uvm */
 #include <miscfs/specfs/specdev.h>
 SDT_PROVIDER_DEFINE(io);
 SDT_PROBE_DEFINE4(io, kernel, , bbusy__start,
     "struct buf *"/*bp*/,
     "bool"/*intr*/, "int"/*timo*/, "kmutex_t *"/*interlock*/);
 SDT_PROBE_DEFINE5(io, kernel, , bbusy__done,
     "struct buf *"/*bp*/,
     "bool"/*intr*/,
     "int"/*timo*/,
     "kmutex_t *"/*interlock*/,
     "int"/*error*/);
 SDT_PROBE_DEFINE0(io, kernel, , getnewbuf__start);
 SDT_PROBE_DEFINE1(io, kernel, , getnewbuf__done,  "struct buf *"/*bp*/);
 SDT_PROBE_DEFINE3(io, kernel, , getblk__start,
     "struct vnode *"/*vp*/, "daddr_t"/*blkno*/, "int"/*size*/);
 SDT_PROBE_DEFINE4(io, kernel, , getblk__done,
     "struct vnode *"/*vp*/, "daddr_t"/*blkno*/, "int"/*size*/,
     "struct buf *"/*bp*/);
 SDT_PROBE_DEFINE2(io, kernel, , brelse, "struct buf *"/*bp*/, "int"/*set*/);
 SDT_PROBE_DEFINE1(io, kernel, , wait__start, "struct buf *"/*bp*/);
 SDT_PROBE_DEFINE1(io, kernel, , wait__done, "struct buf *"/*bp*/);
 #ifndef	BUFPAGES
 # define BUFPAGES 0
 #endif
 #ifdef BUFCACHE
 # if (BUFCACHE < 5) || (BUFCACHE > 95)
 #  error BUFCACHE is not between 5 and 95
 # endif
 #else
 # define BUFCACHE 15
 #endif
 u_int	nbuf;			/* desired number of buffer headers */
 u_int	bufpages = BUFPAGES;	/* optional hardwired count */
 u_int	bufcache = BUFCACHE;	/* max % of RAM to use for buffer cache */
 /*
  * Definitions for the buffer free lists.
  */
 #define	BQUEUES		3		/* number of free buffer queues */
 #define	BQ_LOCKED	0		/* super-blocks &c */
 #define	BQ_LRU		1		/* lru, useful buffers */
 #define	BQ_AGE		2		/* rubbish */
 struct bqueue {
 	TAILQ_HEAD(, buf) bq_queue;
 	uint64_t bq_bytes;
 	buf_t *bq_marker;
 };
 static struct bqueue bufqueues[BQUEUES] __cacheline_aligned;
 /* Function prototypes */
 static void buf_setwm(void);
 static int buf_trim(void);
 static void *bufpool_page_alloc(struct pool *, int);
 static void bufpool_page_free(struct pool *, void *);
 static buf_t *bio_doread(struct vnode *, daddr_t, int, int);
 static buf_t *getnewbuf(int, int, int);
 static int buf_lotsfree(void);
 static int buf_canrelease(void);
 static u_long buf_mempoolidx(u_long);
 static u_long buf_roundsize(u_long);
 static void *buf_alloc(size_t);
 static void buf_mrelease(void *, size_t);
 static void binsheadfree(buf_t *, struct bqueue *);
 static void binstailfree(buf_t *, struct bqueue *);
 #ifdef DEBUG
 static int checkfreelist(buf_t *, struct bqueue *, int);
 #endif
 static void biointr(void *);
 static void biodone2(buf_t *);
 static void sysctl_kern_buf_setup(void);
 static void sysctl_vm_buf_setup(void);
 /* Initialization for biohist */
 #include <sys/biohist.h>
 BIOHIST_DEFINE(biohist);
 void
 biohist_init(void)
+{
 	BIOHIST_INIT(biohist, BIOHIST_SIZE);
+}
 /*
  * Definitions for the buffer hash lists.
  */
 #define	BUFHASH(dvp, lbn)	\
 	(&bufhashtbl[(((long)(dvp) >> 8) + (int)(lbn)) & bufhash])
 LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash;
 u_long	bufhash;
 static int     bufhash_stats(struct hashstat_sysctl *, bool);
 static kcondvar_t needbuffer_cv;
 /*
  * Buffer queue lock.
  */
 kmutex_t bufcache_lock __cacheline_aligned;
 kmutex_t buffer_lock __cacheline_aligned;
 /* Software ISR for completed transfers. */
 static void *biodone_sih;
 /* Buffer pool for I/O buffers. */
 static pool_cache_t buf_cache;
 static pool_cache_t bufio_cache;
 #define MEMPOOL_INDEX_OFFSET (ilog2(DEV_BSIZE))	/* smallest pool is 512 bytes */
 #define NMEMPOOLS (ilog2(MAXBSIZE) - MEMPOOL_INDEX_OFFSET + 1)
 __CTASSERT((1 << (NMEMPOOLS + MEMPOOL_INDEX_OFFSET - 1)) == MAXBSIZE);
 /* Buffer memory pools */
 static struct pool bmempools[NMEMPOOLS];
 static struct vm_map *buf_map;
 /*
  * Buffer memory pool allocator.
  */
 static void *
 bufpool_page_alloc(struct pool *pp, int flags)
+{
 	return (void *)uvm_km_alloc(buf_map,
 	    MAXBSIZE, MAXBSIZE,
 	    ((flags & PR_WAITOK) ? 0 : UVM_KMF_NOWAIT|UVM_KMF_TRYLOCK)
 	    | UVM_KMF_WIRED);
+}
 static void
 bufpool_page_free(struct pool *pp, void *v)
+{
 	uvm_km_free(buf_map, (vaddr_t)v, MAXBSIZE, UVM_KMF_WIRED);
+}
 static struct pool_allocator bufmempool_allocator = {
 	.pa_alloc = bufpool_page_alloc,
 	.pa_free = bufpool_page_free,
 	.pa_pagesz = MAXBSIZE,
 };
 /* Buffer memory management variables */
 u_long bufmem_valimit;
 u_long bufmem_hiwater;
 u_long bufmem_lowater;
 u_long bufmem;
 /*
  * MD code can call this to set a hard limit on the amount
  * of virtual memory used by the buffer cache.
  */
 int
 buf_setvalimit(vsize_t sz)
+{
 	/* We need to accommodate at least NMEMPOOLS of MAXBSIZE each */
 	if (sz < NMEMPOOLS * MAXBSIZE)
 		return EINVAL;
 	bufmem_valimit = sz;
 	return 0;
+}
 static void
 buf_setwm(void)
+{
 	bufmem_hiwater = buf_memcalc();
 	/* lowater is approx. 2% of memory (with bufcache = 15) */
 #define	BUFMEM_WMSHIFT	3
 #define	BUFMEM_HIWMMIN	(64 * 1024 << BUFMEM_WMSHIFT)
 	if (bufmem_hiwater < BUFMEM_HIWMMIN)
 		/* Ensure a reasonable minimum value */
 		bufmem_hiwater = BUFMEM_HIWMMIN;
 	bufmem_lowater = bufmem_hiwater >> BUFMEM_WMSHIFT;
+}
 #ifdef DEBUG
 int debug_verify_freelist = 0;
 static int
 checkfreelist(buf_t *bp, struct bqueue *dp, int ison)
+{
 	buf_t *b;
 	if (!debug_verify_freelist)
 		return 1;
 	TAILQ_FOREACH(b, &dp->bq_queue, b_freelist) {
 		if (b == bp)
 			return ison ? 1 : 0;
+	}
 	return ison ? 0 : 1;
+}
 #endif
 /*
  * Insq/Remq for the buffer hash lists.
  * Call with buffer queue locked.
  */
 static void
 binsheadfree(buf_t *bp, struct bqueue *dp)
+{
 	KASSERT(mutex_owned(&bufcache_lock));
 	KASSERT(bp->b_freelistindex == -1);
 	TAILQ_INSERT_HEAD(&dp->bq_queue, bp, b_freelist);
 	dp->bq_bytes += bp->b_bufsize;
 	bp->b_freelistindex = dp - bufqueues;
+}
 static void
 binstailfree(buf_t *bp, struct bqueue *dp)
+{
 	KASSERT(mutex_owned(&bufcache_lock));
 	KASSERTMSG(bp->b_freelistindex == -1, "double free of buffer? "
 	    "bp=%p, b_freelistindex=%d\n", bp, bp->b_freelistindex);
 	TAILQ_INSERT_TAIL(&dp->bq_queue, bp, b_freelist);
 	dp->bq_bytes += bp->b_bufsize;
 	bp->b_freelistindex = dp - bufqueues;
+}
 void
 bremfree(buf_t *bp)
+{
 	struct bqueue *dp;
 	int bqidx = bp->b_freelistindex;
 	KASSERT(mutex_owned(&bufcache_lock));
 	KASSERT(bqidx != -1);
 	dp = &bufqueues[bqidx];
 	KDASSERT(checkfreelist(bp, dp, 1));
 	KASSERT(dp->bq_bytes >= bp->b_bufsize);
 	TAILQ_REMOVE(&dp->bq_queue, bp, b_freelist);
 	dp->bq_bytes -= bp->b_bufsize;
 	/* For the sysctl helper. */
 	if (bp == dp->bq_marker)
 		dp->bq_marker = NULL;
 #if defined(DIAGNOSTIC)
 	bp->b_freelistindex = -1;
 #endif /* defined(DIAGNOSTIC) */
+}
 /*
  * note that for some ports this is used by pmap bootstrap code to
  * determine kva size.
  */
 u_long
 buf_memcalc(void)
+{
 	u_long n;
 	vsize_t mapsz = 0;
 	/*
 	 * Determine the upper bound of memory to use for buffers.
+	 *
 	 *	- If bufpages is specified, use that as the number
 	 *	  pages.
+	 *
 	 *	- Otherwise, use bufcache as the percentage of
 	 *	  physical memory.
 	 */
 	if (bufpages != 0) {
 		n = bufpages;
 	} else {
 		if (bufcache < 5) {
 			printf("forcing bufcache %d -> 5", bufcache);
 			bufcache = 5;
+		}
 		if (bufcache > 95) {
 			printf("forcing bufcache %d -> 95", bufcache);
 			bufcache = 95;
+		}
 		if (buf_map != NULL)
 			mapsz = vm_map_max(buf_map) - vm_map_min(buf_map);
 		n = calc_cache_size(mapsz, bufcache,
 		    (buf_map != kernel_map) ? 100 : BUFCACHE_VA_MAXPCT)
 		    / PAGE_SIZE;
+	}
 	n <<= PAGE_SHIFT;
 	if (bufmem_valimit != 0 && n > bufmem_valimit)
 		n = bufmem_valimit;
 	return (n);
+}
 /*
  * Initialize buffers and hash links for buffers.
  */
 void
 bufinit(void)
+{
 	struct bqueue *dp;
 	int use_std;
 	u_int i;
 	biodone_vfs = biodone;
 	mutex_init(&bufcache_lock, MUTEX_DEFAULT, IPL_NONE);
 	mutex_init(&buffer_lock, MUTEX_DEFAULT, IPL_NONE);
 	cv_init(&needbuffer_cv, "needbuf");
 	if (bufmem_valimit != 0) {
 		vaddr_t minaddr = 0, maxaddr;
 		buf_map = uvm_km_suballoc(kernel_map, &minaddr, &maxaddr,
 					  bufmem_valimit, 0, false, 0);
 		if (buf_map == NULL)
 			panic("bufinit: cannot allocate submap");
 	} else
 		buf_map = kernel_map;
 	/*
 	 * Initialize buffer cache memory parameters.
 	 */
 	bufmem = 0;
 	buf_setwm();
 	/* On "small" machines use small pool page sizes where possible */
 	use_std = (physmem < atop(16*1024*1024));
 	/*
 	 * Also use them on systems that can map the pool pages using
 	 * a direct-mapped segment.
 	 */
 #ifdef PMAP_MAP_POOLPAGE
 	use_std = 1;
 #endif
 	buf_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0,
 	    "bufpl", NULL, IPL_SOFTBIO, NULL, NULL, NULL);
 	bufio_cache = pool_cache_init(sizeof(buf_t), 0, 0, 0,
 	    "biopl", NULL, IPL_BIO, NULL, NULL, NULL);
 	for (i = 0; i < NMEMPOOLS; i++) {
 		struct pool_allocator *pa;
 		struct pool *pp = &bmempools[i];
 		u_int size = 1 << (i + MEMPOOL_INDEX_OFFSET);
 		char *name = kmem_alloc(8, KM_SLEEP); /* XXX: never freed */
 		if (__predict_false(size >= 1048576))
 			(void)snprintf(name, 8, "buf%um", size / 1048576);
 		else if (__predict_true(size >= 1024))
 			(void)snprintf(name, 8, "buf%uk", size / 1024);
 		else
 			(void)snprintf(name, 8, "buf%ub", size);
 		pa = (size <= PAGE_SIZE && use_std)
 			? &pool_allocator_nointr
 			: &bufmempool_allocator;
 		pool_init(pp, size, DEV_BSIZE, 0, 0, name, pa, IPL_NONE);
 		pool_setlowat(pp, 1);
 		pool_sethiwat(pp, 1);
+	}
 	/* Initialize the buffer queues */
 	for (dp = bufqueues; dp < &bufqueues[BQUEUES]; dp++) {
 		TAILQ_INIT(&dp->bq_queue);
 		dp->bq_bytes = 0;
+	}
 	/*
 	 * Estimate hash table size based on the amount of memory we
 	 * intend to use for the buffer cache. The average buffer
 	 * size is dependent on our clients (i.e. filesystems).
+	 *
 	 * For now, use an empirical 3K per buffer.
 	 */
 	nbuf = (bufmem_hiwater / 1024) / 3;
 	bufhashtbl = hashinit(nbuf, HASH_LIST, true, &bufhash);
 	sysctl_kern_buf_setup();
 	sysctl_vm_buf_setup();
 	hashstat_register("bufhash", bufhash_stats);
+}
 void
 bufinit2(void)
+{
 	biodone_sih = softint_establish(SOFTINT_BIO | SOFTINT_MPSAFE, biointr,
 	    NULL);
 	if (biodone_sih == NULL)
 		panic("bufinit2: can't establish soft interrupt");
+}
 static int
 buf_lotsfree(void)
+{
 	u_long guess;
 	/* Always allocate if less than the low water mark. */
 	if (bufmem < bufmem_lowater)
 		return 1;
 	/* Never allocate if greater than the high water mark. */
 	if (bufmem > bufmem_hiwater)
 		return 0;
 	/* If there's anything on the AGE list, it should be eaten. */
 	if (TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue) != NULL)
 		return 0;
 	/*
 	 * The probabily of getting a new allocation is inversely
 	 * proportional  to the current size of the cache above
 	 * the low water mark.  Divide the total first to avoid overflows
 	 * in the product.
 	 */
 	guess = cprng_fast32() % 16;
 	if ((bufmem_hiwater - bufmem_lowater) / 16 * guess >=
 	    (bufmem - bufmem_lowater))
 		return 1;
 	/* Otherwise don't allocate. */
 	return 0;
+}
 /*
  * Return estimate of bytes we think need to be
  * released to help resolve low memory conditions.
+ *
  * => called with bufcache_lock held.
  */
 static int
 buf_canrelease(void)
+{
 	int pagedemand, ninvalid = 0;
 	KASSERT(mutex_owned(&bufcache_lock));
 	if (bufmem < bufmem_lowater)
 		return 0;
 	if (bufmem > bufmem_hiwater)
 		return bufmem - bufmem_hiwater;
 	ninvalid += bufqueues[BQ_AGE].bq_bytes;
 	pagedemand = uvmexp.freetarg - uvm_availmem(false);
 	if (pagedemand < 0)
 		return ninvalid;
 	return MAX(ninvalid, MIN(2 * MAXBSIZE,
 	    MIN((bufmem - bufmem_lowater) / 16, pagedemand * PAGE_SIZE)));
+}
 /*
  * Buffer memory allocation helper functions
  */
 static u_long
 buf_mempoolidx(u_long size)
+{
 	u_int n = 0;
 	size -= 1;
 	size >>= MEMPOOL_INDEX_OFFSET;
 	while (size) {
 		size >>= 1;
 		n += 1;
+	}
 	if (n >= NMEMPOOLS)
 		panic("buf mem pool index %d", n);
 	return n;
+}
 static u_long
 buf_roundsize(u_long size)
+{
 	/* Round up to nearest power of 2 */
 	return (1 << (buf_mempoolidx(size) + MEMPOOL_INDEX_OFFSET));
+}
 static void *
 buf_alloc(size_t size)
+{
 	u_int n = buf_mempoolidx(size);
 	void *addr;
 	while (1) {
 		addr = pool_get(&bmempools[n], PR_NOWAIT);
 		if (addr != NULL)
 			break;
 		/* No memory, see if we can free some. If so, try again */
 		mutex_enter(&bufcache_lock);
 		if (buf_drain(1) > 0) {
 			mutex_exit(&bufcache_lock);
 			continue;
+		}
 		if (curlwp == uvm.pagedaemon_lwp) {
 			mutex_exit(&bufcache_lock);
 			return NULL;
+		}
 		/* Wait for buffers to arrive on the LRU queue */
 		cv_timedwait(&needbuffer_cv, &bufcache_lock, hz / 4);
 		mutex_exit(&bufcache_lock);
+	}
 	return addr;
+}
 static void
 buf_mrelease(void *addr, size_t size)
+{
 	pool_put(&bmempools[buf_mempoolidx(size)], addr);
+}
 /*
  * bread()/breadn() helper.
  */
 static buf_t *
 bio_doread(struct vnode *vp, daddr_t blkno, int size, int async)
+{
 	buf_t *bp;
 	struct mount *mp;
 	bp = getblk(vp, blkno, size, 0, 0);
 	/*
 	 * getblk() may return NULL if we are the pagedaemon.
 	 */
 	if (bp == NULL) {
 		KASSERT(curlwp == uvm.pagedaemon_lwp);
 		return NULL;
+	}
 	/*
 	 * If buffer does not have data valid, start a read.
 	 * Note that if buffer is BC_INVAL, getblk() won't return it.
 	 * Therefore, it's valid if its I/O has completed or been delayed.
 	 */
 	if (!ISSET(bp->b_oflags, (BO_DONE | BO_DELWRI))) {
 		/* Start I/O for the buffer. */
 		SET(bp->b_flags, B_READ | async);
 		if (async)
 			BIO_SETPRIO(bp, BPRIO_TIMELIMITED);
 		else
 			BIO_SETPRIO(bp, BPRIO_TIMECRITICAL);
 		VOP_STRATEGY(vp, bp);
 		/* Pay for the read. */
 		curlwp->l_ru.ru_inblock++;
 	} else if (async)
 		brelse(bp, 0);
 	if (vp->v_type == VBLK)
 		mp = spec_node_getmountedfs(vp);
 	else
 		mp = vp->v_mount;
 	/*
 	 * Collect statistics on synchronous and asynchronous reads.
 	 * Reads from block devices are charged to their associated
 	 * filesystem (if any).
 	 */
 	if (mp != NULL) {
 		if (async == 0)
 			mp->mnt_stat.f_syncreads++;
 		else
 			mp->mnt_stat.f_asyncreads++;
+	}
 	return (bp);
+}
 /*
  * Read a disk block.
  * This algorithm described in Bach (p.54).
  */
 int
 bread(struct vnode *vp, daddr_t blkno, int size, int flags, buf_t **bpp)
+{
 	buf_t *bp;
 	int error;
 	BIOHIST_FUNC(__func__); BIOHIST_CALLED(biohist);
 	/* Get buffer for block. */
 	bp = *bpp = bio_doread(vp, blkno, size, 0);
 	if (bp == NULL)
 		return ENOMEM;
 	/* Wait for the read to complete, and return result. */
 	error = biowait(bp);
 	if (error == 0 && (flags & B_MODIFY) != 0)
 		error = fscow_run(bp, true);
 	if (error) {
 		brelse(bp, 0);
 		*bpp = NULL;
+	}
 	return error;
+}
 /*
  * Read-ahead multiple disk blocks. The first is sync, the rest async.
  * Trivial modification to the breada algorithm presented in Bach (p.55).
  */
 int
 breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablks,
     int *rasizes, int nrablks, int flags, buf_t **bpp)
+{
 	buf_t *bp;
 	int error, i;
 	BIOHIST_FUNC(__func__); BIOHIST_CALLED(biohist);
 	bp = *bpp = bio_doread(vp, blkno, size, 0);
 	if (bp == NULL)
 		return ENOMEM;
 	/*
 	 * For each of the read-ahead blocks, start a read, if necessary.
 	 */
 	mutex_enter(&bufcache_lock);
 	for (i = 0; i < nrablks; i++) {
 		/* If it's in the cache, just go on to next one. */
 		if (incore(vp, rablks[i]))
 			continue;
 		/* Get a buffer for the read-ahead block */
 		mutex_exit(&bufcache_lock);
 		(void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC);
 		mutex_enter(&bufcache_lock);
+	}
 	mutex_exit(&bufcache_lock);
 	/* Otherwise, we had to start a read for it; wait until it's valid. */
 	error = biowait(bp);
 	if (error == 0 && (flags & B_MODIFY) != 0)
 		error = fscow_run(bp, true);
 	if (error) {
 		brelse(bp, 0);
 		*bpp = NULL;
+	}
 	return error;
+}
 /*
  * Block write.  Described in Bach (p.56)
  */
 int
 bwrite(buf_t *bp)
+{
 	int rv, sync, wasdelayed;
 	struct vnode *vp;
 	struct mount *mp;
 	BIOHIST_FUNC(__func__); BIOHIST_CALLARGS(biohist, "bp=%#jx",
 	    (uintptr_t)bp, 0, 0, 0);
 	KASSERT(ISSET(bp->b_cflags, BC_BUSY));
 	KASSERT(!cv_has_waiters(&bp->b_done));
 	vp = bp->b_vp;
 	/*
 	 * dholland 20160728 AFAICT vp==NULL must be impossible as it
 	 * will crash upon reaching VOP_STRATEGY below... see further
 	 * analysis on tech-kern.
 	 */
 	KASSERTMSG(vp != NULL, "bwrite given buffer with null vnode");
 	if (vp != NULL) {
 		KASSERT(bp->b_objlock == vp->v_interlock);
 		if (vp->v_type == VBLK)
 			mp = spec_node_getmountedfs(vp);
 		else
 			mp = vp->v_mount;
 	} else {
 		mp = NULL;
+	}
 	if (mp && mp->mnt_wapbl) {
 		if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) {
 			bdwrite(bp);
 			return 0;
+		}
+	}
 	/*
 	 * Remember buffer type, to switch on it later.  If the write was
 	 * synchronous, but the file system was mounted with MNT_ASYNC,
 	 * convert it to a delayed write.
 	 * XXX note that this relies on delayed tape writes being converted
 	 * to async, not sync writes (which is safe, but ugly).
 	 */
 	sync = !ISSET(bp->b_flags, B_ASYNC);
 	if (sync && mp != NULL && ISSET(mp->mnt_flag, MNT_ASYNC)) {
 		bdwrite(bp);
 		return (0);
+	}
 	/*
 	 * Collect statistics on synchronous and asynchronous writes.
 	 * Writes to block devices are charged to their associated
 	 * filesystem (if any).
 	 */
 	if (mp != NULL) {
 		if (sync)
 			mp->mnt_stat.f_syncwrites++;
 		else
 			mp->mnt_stat.f_asyncwrites++;
+	}
 	/*
 	 * Pay for the I/O operation and make sure the buf is on the correct
 	 * vnode queue.
 	 */
 	bp->b_error = 0;
 	wasdelayed = ISSET(bp->b_oflags, BO_DELWRI);
 	CLR(bp->b_flags, B_READ);
 	if (wasdelayed) {
 		mutex_enter(&bufcache_lock);
 		mutex_enter(bp->b_objlock);
 		CLR(bp->b_oflags, BO_DONE | BO_DELWRI);
 		reassignbuf(bp, bp->b_vp);
 		/* Wake anyone trying to busy the buffer via vnode's lists. */
 		cv_broadcast(&bp->b_busy);
 		mutex_exit(&bufcache_lock);
 	} else {
 		curlwp->l_ru.ru_oublock++;
 		mutex_enter(bp->b_objlock);
 		CLR(bp->b_oflags, BO_DONE | BO_DELWRI);
+	}
 	if (vp != NULL)
 		vp->v_numoutput++;
 	mutex_exit(bp->b_objlock);
 	/* Initiate disk write. */
 	if (sync)
 		BIO_SETPRIO(bp, BPRIO_TIMECRITICAL);
 	else
 		BIO_SETPRIO(bp, BPRIO_TIMELIMITED);
 	VOP_STRATEGY(vp, bp);
 	if (sync) {
 		/* If I/O was synchronous, wait for it to complete. */
 		rv = biowait(bp);
 		/* Release the buffer. */
 		brelse(bp, 0);
 		return (rv);
 	} else {
 		return (0);
+	}
+}
 int
 vn_bwrite(void *v)
+{
 	struct vop_bwrite_args *ap = v;
 	return (bwrite(ap->a_bp));
+}
 /*
  * Delayed write.
+ *
  * The buffer is marked dirty, but is not queued for I/O.
  * This routine should be used when the buffer is expected
  * to be modified again soon, typically a small write that
  * partially fills a buffer.
+ *
  * NB: magnetic tapes cannot be delayed; they must be
  * written in the order that the writes are requested.
+ *
  * Described in Leffler, et al. (pp. 208-213).
  */
 void
 bdwrite(buf_t *bp)
+{
 	BIOHIST_FUNC(__func__); BIOHIST_CALLARGS(biohist, "bp=%#jx",
 	    (uintptr_t)bp, 0, 0, 0);
 	KASSERT(bp->b_vp == NULL || bp->b_vp->v_tag != VT_UFS ||
 	    bp->b_vp->v_type == VBLK || ISSET(bp->b_flags, B_COWDONE));
 	KASSERT(ISSET(bp->b_cflags, BC_BUSY));
 	KASSERT(!cv_has_waiters(&bp->b_done));
 	/* If this is a tape block, write the block now. */
 	if (bdev_type(bp->b_dev) == D_TAPE) {
 		bawrite(bp);
 		return;
+	}
 	if (wapbl_vphaswapbl(bp->b_vp)) {
 		struct mount *mp = wapbl_vptomp(bp->b_vp);
 		if (bp->b_iodone != mp->mnt_wapbl_op->wo_wapbl_biodone) {
 			WAPBL_ADD_BUF(mp, bp);
+		}
+	}
 	/*
 	 * If the block hasn't been seen before:
 	 *	(1) Mark it as having been seen,
 	 *	(2) Charge for the write,
 	 *	(3) Make sure it's on its vnode's correct block list.
 	 */
 	KASSERT(bp->b_vp == NULL || bp->b_objlock == bp->b_vp->v_interlock);
 	if (!ISSET(bp->b_oflags, BO_DELWRI)) {
 		mutex_enter(&bufcache_lock);
 		mutex_enter(bp->b_objlock);
 		SET(bp->b_oflags, BO_DELWRI);
 		curlwp->l_ru.ru_oublock++;
 		reassignbuf(bp, bp->b_vp);
 		/* Wake anyone trying to busy the buffer via vnode's lists. */
 		cv_broadcast(&bp->b_busy);
 		mutex_exit(&bufcache_lock);
 	} else {
 		mutex_enter(bp->b_objlock);
+	}
 	/* Otherwise, the "write" is done, so mark and release the buffer. */
 	CLR(bp->b_oflags, BO_DONE);
 	mutex_exit(bp->b_objlock);
 	brelse(bp, 0);
+}
 /*
  * Asynchronous block write; just an asynchronous bwrite().
  */
 void
 bawrite(buf_t *bp)
+{
 	KASSERT(ISSET(bp->b_cflags, BC_BUSY));
 	KASSERT(bp->b_vp != NULL);
 	SET(bp->b_flags, B_ASYNC);
 	VOP_BWRITE(bp->b_vp, bp);
+}
 /*
  * Release a buffer on to the free lists.
  * Described in Bach (p. 46).
  */
 void
 brelsel(buf_t *bp, int set)
+{
 	struct bqueue *bufq;
 	struct vnode *vp;
 	SDT_PROBE2(io, kernel, , brelse,  bp, set);
 	KASSERT(bp != NULL);
 	KASSERT(mutex_owned(&bufcache_lock));
 	KASSERT(!cv_has_waiters(&bp->b_done));
 	SET(bp->b_cflags, set);
 	KASSERT(ISSET(bp->b_cflags, BC_BUSY));
 	KASSERT(bp->b_iodone == NULL);
 	/* Wake up any processes waiting for any buffer to become free. */
 	cv_signal(&needbuffer_cv);
 	/* Wake up any proceeses waiting for _this_ buffer to become free */
 	if (ISSET(bp->b_cflags, BC_WANTED))
 		CLR(bp->b_cflags, BC_WANTED|BC_AGE);
 	/* If it's clean clear the copy-on-write flag. */
 	if (ISSET(bp->b_flags, B_COWDONE)) {
 		mutex_enter(bp->b_objlock);
 		if (!ISSET(bp->b_oflags, BO_DELWRI))
 			CLR(bp->b_flags, B_COWDONE);
 		mutex_exit(bp->b_objlock);
+	}
 	/*
 	 * Determine which queue the buffer should be on, then put it there.
 	 */
 	/* If it's locked, don't report an error; try again later. */
 	if (ISSET(bp->b_flags, B_LOCKED))
 		bp->b_error = 0;
 	/* If it's not cacheable, or an error, mark it invalid. */
 	if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0)
 		SET(bp->b_cflags, BC_INVAL);
 	if (ISSET(bp->b_cflags, BC_VFLUSH)) {
 		/*
 		 * This is a delayed write buffer that was just flushed to
 		 * disk.  It is still on the LRU queue.  If it's become
 		 * invalid, then we need to move it to a different queue;
 		 * otherwise leave it in its current position.
 		 */
 		CLR(bp->b_cflags, BC_VFLUSH);
 		if (!ISSET(bp->b_cflags, BC_INVAL|BC_AGE) &&
 		    !ISSET(bp->b_flags, B_LOCKED) && bp->b_error == 0) {
 			KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 1));
 			goto already_queued;
 		} else {
 			bremfree(bp);
+		}
+	}
 	KDASSERT(checkfreelist(bp, &bufqueues[BQ_AGE], 0));
 	KDASSERT(checkfreelist(bp, &bufqueues[BQ_LRU], 0));
 	KDASSERT(checkfreelist(bp, &bufqueues[BQ_LOCKED], 0));
 	if ((bp->b_bufsize <= 0) || ISSET(bp->b_cflags, BC_INVAL)) {
 		/*
 		 * If it's invalid or empty, dissociate it from its vnode
 		 * and put on the head of the appropriate queue.
 		 */
 		if (ISSET(bp->b_flags, B_LOCKED)) {
 			if (wapbl_vphaswapbl(vp = bp->b_vp)) {
 				struct mount *mp = wapbl_vptomp(vp);
 				KASSERT(bp->b_iodone
 				    != mp->mnt_wapbl_op->wo_wapbl_biodone);
 				WAPBL_REMOVE_BUF(mp, bp);
+			}
+		}
 		mutex_enter(bp->b_objlock);
 		CLR(bp->b_oflags, BO_DONE|BO_DELWRI);
 		if ((vp = bp->b_vp) != NULL) {
 			KASSERT(bp->b_objlock == vp->v_interlock);
 			reassignbuf(bp, bp->b_vp);
 			brelvp(bp);
 			mutex_exit(vp->v_interlock);
 		} else {
 			KASSERT(bp->b_objlock == &buffer_lock);
 			mutex_exit(bp->b_objlock);
+		}
 		/* We want to dispose of the buffer, so wake everybody. */
 		cv_broadcast(&bp->b_busy);
 		if (bp->b_bufsize <= 0)
 			/* no data */
 			goto already_queued;
 		else
 			/* invalid data */
 			bufq = &bufqueues[BQ_AGE];
 		binsheadfree(bp, bufq);
 	} else  {
 		/*
 		 * It has valid data.  Put it on the end of the appropriate
 		 * queue, so that it'll stick around for as long as possible.
 		 * If buf is AGE, but has dependencies, must put it on last
 		 * bufqueue to be scanned, ie LRU. This protects against the
 		 * livelock where BQ_AGE only has buffers with dependencies,
 		 * and we thus never get to the dependent buffers in BQ_LRU.
 		 */
 		if (ISSET(bp->b_flags, B_LOCKED)) {
 			/* locked in core */
 			bufq = &bufqueues[BQ_LOCKED];
 		} else if (!ISSET(bp->b_cflags, BC_AGE)) {
 			/* valid data */
 			bufq = &bufqueues[BQ_LRU];
 		} else {
 			/* stale but valid data */
 			bufq = &bufqueues[BQ_AGE];
+		}
 		binstailfree(bp, bufq);
+	}
 already_queued:
 	/* Unlock the buffer. */
 	CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE);
 	CLR(bp->b_flags, B_ASYNC);
 	/*
 	 * Wake only the highest priority waiter on the lock, in order to
 	 * prevent a thundering herd: many LWPs simultaneously awakening and
 	 * competing for the buffer's lock.  Testing in 2019 revealed this
 	 * to reduce contention on bufcache_lock tenfold during a kernel
 	 * compile.  Here and elsewhere, when the buffer is changing
 	 * identity, being disposed of, or moving from one list to another,
 	 * we wake all lock requestors.
 	 */
 	if (bp->b_bufsize <= 0) {
 		cv_broadcast(&bp->b_busy);
 		buf_destroy(bp);
 #ifdef DEBUG
 		memset((char *)bp, 0, sizeof(*bp));
 #endif
 		pool_cache_put(buf_cache, bp);
 	} else
 		cv_signal(&bp->b_busy);
+}
 void
 brelse(buf_t *bp, int set)
+{
 	mutex_enter(&bufcache_lock);
 	brelsel(bp, set);
 	mutex_exit(&bufcache_lock);
+}
 /*
  * Determine if a block is in the cache.
  * Just look on what would be its hash chain.  If it's there, return
  * a pointer to it, unless it's marked invalid.  If it's marked invalid,
  * we normally don't return the buffer, unless the caller explicitly
  * wants us to.
  */
 buf_t *
 incore(struct vnode *vp, daddr_t blkno)
+{
 	buf_t *bp;
 	KASSERT(mutex_owned(&bufcache_lock));
 	/* Search hash chain */
 	LIST_FOREACH(bp, BUFHASH(vp, blkno), b_hash) {
 		if (bp->b_lblkno == blkno && bp->b_vp == vp &&
 		    !ISSET(bp->b_cflags, BC_INVAL)) {
 		    	KASSERT(bp->b_objlock == vp->v_interlock);
 		    	return (bp);
+		}
+	}
 	return (NULL);
+}
 /*
  * Get a block of requested size that is associated with
  * a given vnode and block offset. If it is found in the
  * block cache, mark it as having been found, make it busy
  * and return it. Otherwise, return an empty block of the
  * correct size. It is up to the caller to insure that the
  * cached blocks be of the correct size.
  */
 buf_t *
 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo)
+{
 	int err, preserve;
 	buf_t *bp;
 	mutex_enter(&bufcache_lock);
 	SDT_PROBE3(io, kernel, , getblk__start,  vp, blkno, size);
  loop:
 	bp = incore(vp, blkno);
 	if (bp != NULL) {
 		err = bbusy(bp, ((slpflag & PCATCH) != 0), slptimeo, NULL);
 		if (err != 0) {
 			if (err == EPASSTHROUGH)
 				goto loop;
 			mutex_exit(&bufcache_lock);
 			SDT_PROBE4(io, kernel, , getblk__done,
 			    vp, blkno, size, NULL);
 			return (NULL);
+		}
 		KASSERT(!cv_has_waiters(&bp->b_done));
 #ifdef DIAGNOSTIC
 		if (ISSET(bp->b_oflags, BO_DONE|BO_DELWRI) &&
 		    bp->b_bcount < size && vp->v_type != VBLK)
 			panic("getblk: block size invariant failed");
 #endif
 		bremfree(bp);
 		preserve = 1;
 	} else {
 		if ((bp = getnewbuf(slpflag, slptimeo, 0)) == NULL)
 			goto loop;
 		if (incore(vp, blkno) != NULL) {
 			/* The block has come into memory in the meantime. */
 			brelsel(bp, 0);
 			goto loop;
+		}
 		LIST_INSERT_HEAD(BUFHASH(vp, blkno), bp, b_hash);
 		bp->b_blkno = bp->b_lblkno = bp->b_rawblkno = blkno;
 		mutex_enter(vp->v_interlock);
 		bgetvp(vp, bp);
 		mutex_exit(vp->v_interlock);
 		preserve = 0;
+	}
 	mutex_exit(&bufcache_lock);
 	/*
 	 * LFS can't track total size of B_LOCKED buffer (locked_queue_bytes)
 	 * if we re-size buffers here.
 	 */
 	if (ISSET(bp->b_flags, B_LOCKED)) {
 		KASSERT(bp->b_bufsize >= size);
 	} else {
 		if (allocbuf(bp, size, preserve)) {
 			mutex_enter(&bufcache_lock);
 			LIST_REMOVE(bp, b_hash);
 			brelsel(bp, BC_INVAL);
 			mutex_exit(&bufcache_lock);
 			SDT_PROBE4(io, kernel, , getblk__done,
 			    vp, blkno, size, NULL);
 			return NULL;
+		}
+	}
 	BIO_SETPRIO(bp, BPRIO_DEFAULT);
 	SDT_PROBE4(io, kernel, , getblk__done,  vp, blkno, size, bp);
 	return (bp);
+}
 /*
  * Get an empty, disassociated buffer of given size.
  */
 buf_t *
 geteblk(int size)
+{
 	buf_t *bp;
 	int error __diagused;
 	mutex_enter(&bufcache_lock);
 	while ((bp = getnewbuf(0, 0, 0)) == NULL)
+		;
 	SET(bp->b_cflags, BC_INVAL);
 	LIST_INSERT_HEAD(&invalhash, bp, b_hash);
 	mutex_exit(&bufcache_lock);
 	BIO_SETPRIO(bp, BPRIO_DEFAULT);
 	error = allocbuf(bp, size, 0);
 	KASSERT(error == 0);
 	return (bp);
+}
 /*
  * Expand or contract the actual memory allocated to a buffer.
+ *
  * If the buffer shrinks, data is lost, so it's up to the
  * caller to have written it out *first*; this routine will not
  * start a write.  If the buffer grows, it's the callers
  * responsibility to fill out the buffer's additional contents.
  */
 int
 allocbuf(buf_t *bp, int size, int preserve)
+{
 	void *addr;
 	vsize_t oldsize, desired_size;
 	int oldcount;
 	int delta;
 	desired_size = buf_roundsize(size);
 	if (desired_size > MAXBSIZE)
 		printf("allocbuf: buffer larger than MAXBSIZE requested");
 	oldcount = bp->b_bcount;
 	bp->b_bcount = size;
 	oldsize = bp->b_bufsize;
 	if (oldsize == desired_size) {
 		/*
 		 * Do not short cut the WAPBL resize, as the buffer length
 		 * could still have changed and this would corrupt the
 		 * tracking of the transaction length.
 		 */
 		goto out;
+	}
 	/*
 	 * If we want a buffer of a different size, re-allocate the
 	 * buffer's memory; copy old content only if needed.
 	 */
 	addr = buf_alloc(desired_size);
 	if (addr == NULL)
 		return ENOMEM;
 	if (preserve)
 		memcpy(addr, bp->b_data, MIN(oldsize,desired_size));
 	if (bp->b_data != NULL)
 		buf_mrelease(bp->b_data, oldsize);
 	bp->b_data = addr;
 	bp->b_bufsize = desired_size;
 	/*
 	 * Update overall buffer memory counter (protected by bufcache_lock)
 	 */
 	delta = (long)desired_size - (long)oldsize;
 	mutex_enter(&bufcache_lock);
 	if ((bufmem += delta) > bufmem_hiwater) {
 		/*
 		 * Need to trim overall memory usage.
 		 */
 		while (buf_canrelease()) {
 			if (preempt_needed()) {
 				mutex_exit(&bufcache_lock);
 				preempt();
 				mutex_enter(&bufcache_lock);
+			}
 			if (buf_trim() == 0)
 				break;
+		}
+	}
 	mutex_exit(&bufcache_lock);
  out:
 	if (wapbl_vphaswapbl(bp->b_vp))
 		WAPBL_RESIZE_BUF(wapbl_vptomp(bp->b_vp), bp, oldsize, oldcount);
 	return 0;
+}
 /*
  * Find a buffer which is available for use.
  * Select something from a free list.
  * Preference is to AGE list, then LRU list.
+ *
  * Called with the buffer queues locked.
  * Return buffer locked.
  */
 static buf_t *
 getnewbuf(int slpflag, int slptimeo, int from_bufq)
+{
 	buf_t *bp;
 	struct vnode *vp;
 	struct mount *transmp = NULL;
 	SDT_PROBE0(io, kernel, , getnewbuf__start);
  start:
 	KASSERT(mutex_owned(&bufcache_lock));
 	/*
 	 * Get a new buffer from the pool.
 	 */
 	if (!from_bufq && buf_lotsfree()) {
 		mutex_exit(&bufcache_lock);
 		bp = pool_cache_get(buf_cache, PR_NOWAIT);
 		if (bp != NULL) {
 			memset((char *)bp, 0, sizeof(*bp));
 			buf_init(bp);
 			SET(bp->b_cflags, BC_BUSY);	/* mark buffer busy */
 			mutex_enter(&bufcache_lock);
 #if defined(DIAGNOSTIC)
 			bp->b_freelistindex = -1;
 #endif /* defined(DIAGNOSTIC) */
 			SDT_PROBE1(io, kernel, , getnewbuf__done,  bp);
 			return (bp);
+		}
 		mutex_enter(&bufcache_lock);
+	}
 	KASSERT(mutex_owned(&bufcache_lock));
 	if ((bp = TAILQ_FIRST(&bufqueues[BQ_AGE].bq_queue)) != NULL) {
 		KASSERT(!ISSET(bp->b_oflags, BO_DELWRI));
 	} else {
 		TAILQ_FOREACH(bp, &bufqueues[BQ_LRU].bq_queue, b_freelist) {
 			if (ISSET(bp->b_cflags, BC_VFLUSH) ||
 			    !ISSET(bp->b_oflags, BO_DELWRI))
 				break;
 			if (fstrans_start_nowait(bp->b_vp->v_mount) == 0) {
 				KASSERT(transmp == NULL);
 				transmp = bp->b_vp->v_mount;
 				break;
+			}
+		}
+	}
 	if (bp != NULL) {
 	    	KASSERT(!ISSET(bp->b_cflags, BC_BUSY) || ISSET(bp->b_cflags, BC_VFLUSH));
 		bremfree(bp);
 		/* Buffer is no longer on free lists. */
 		SET(bp->b_cflags, BC_BUSY);
 		/* Wake anyone trying to lock the old identity. */
 		cv_broadcast(&bp->b_busy);
 	} else {
 		/*
 		 * XXX: !from_bufq should be removed.
 		 */
 		if (!from_bufq || curlwp != uvm.pagedaemon_lwp) {
 			/* wait for a free buffer of any kind */
 			if ((slpflag & PCATCH) != 0)
 				(void)cv_timedwait_sig(&needbuffer_cv,
 				    &bufcache_lock, slptimeo);
 			else
 				(void)cv_timedwait(&needbuffer_cv,
 				    &bufcache_lock, slptimeo);
+		}
 		SDT_PROBE1(io, kernel, , getnewbuf__done,  NULL);
 		return (NULL);
+	}
 #ifdef DIAGNOSTIC
 	if (bp->b_bufsize <= 0)
 		panic("buffer %p: on queue but empty", bp);
 #endif
 	if (ISSET(bp->b_cflags, BC_VFLUSH)) {
 		/*
 		 * This is a delayed write buffer being flushed to disk.  Make
 		 * sure it gets aged out of the queue when it's finished, and
 		 * leave it off the LRU queue.
 		 */
 		CLR(bp->b_cflags, BC_VFLUSH);
 		SET(bp->b_cflags, BC_AGE);
 		goto start;
+	}
 	KASSERT(ISSET(bp->b_cflags, BC_BUSY));
     	KASSERT(!cv_has_waiters(&bp->b_done));
 	/*
 	 * If buffer was a delayed write, start it and return NULL
 	 * (since we might sleep while starting the write).
 	 */
 	if (ISSET(bp->b_oflags, BO_DELWRI)) {
 		/*
 		 * This buffer has gone through the LRU, so make sure it gets
 		 * reused ASAP.
 		 */
 		SET(bp->b_cflags, BC_AGE);
 		mutex_exit(&bufcache_lock);
 		bawrite(bp);
 		KASSERT(transmp != NULL);
 		fstrans_done(transmp);
 		mutex_enter(&bufcache_lock);
 		SDT_PROBE1(io, kernel, , getnewbuf__done,  NULL);
 		return (NULL);
+	}
 	KASSERT(transmp == NULL);
 	vp = bp->b_vp;
 	/* clear out various other fields */
 	bp->b_cflags = BC_BUSY;
 	bp->b_oflags = 0;
 	bp->b_flags = 0;
 	bp->b_dev = NODEV;
 	bp->b_blkno = 0;
 	bp->b_lblkno = 0;
 	bp->b_rawblkno = 0;
 	bp->b_iodone = 0;
 	bp->b_error = 0;
 	bp->b_resid = 0;
 	bp->b_bcount = 0;
 	LIST_REMOVE(bp, b_hash);
 	/* Disassociate us from our vnode, if we had one... */
 	if (vp != NULL) {
 		mutex_enter(vp->v_interlock);
 		brelvp(bp);
 		mutex_exit(vp->v_interlock);
+	}
 	SDT_PROBE1(io, kernel, , getnewbuf__done,  bp);
 	return (bp);
+}
 /*
  * Invalidate the specified buffer if it exists.
  */
 void
 binvalbuf(struct vnode *vp, daddr_t blkno)
+{
 	buf_t *bp;
 	int err;
 	mutex_enter(&bufcache_lock);
  loop:
 	bp = incore(vp, blkno);
 	if (bp != NULL) {
 		err = bbusy(bp, 0, 0, NULL);
 		if (err == EPASSTHROUGH)
 			goto loop;
 		bremfree(bp);
 		if (ISSET(bp->b_oflags, BO_DELWRI)) {
 			SET(bp->b_cflags, BC_NOCACHE);
 			mutex_exit(&bufcache_lock);
 			bwrite(bp);
 		} else {
 			brelsel(bp, BC_INVAL);
 			mutex_exit(&bufcache_lock);
+		}
 	} else
 		mutex_exit(&bufcache_lock);
+}
 /*
  * Attempt to free an aged buffer off the queues.
  * Called with queue lock held.
  * Returns the amount of buffer memory freed.
  */
 static int
 buf_trim(void)
+{
 	buf_t *bp;
 	long size;
 	KASSERT(mutex_owned(&bufcache_lock));
 	/* Instruct getnewbuf() to get buffers off the queues */
 	if ((bp = getnewbuf(PCATCH, 1, 1)) == NULL)
 		return 0;
 	KASSERT((bp->b_cflags & BC_WANTED) == 0);
 	size = bp->b_bufsize;
 	bufmem -= size;
 	if (size > 0) {
 		buf_mrelease(bp->b_data, size);
 		bp->b_bcount = bp->b_bufsize = 0;
+	}
 	/* brelse() will return the buffer to the global buffer pool */
 	brelsel(bp, 0);
 	return size;
+}
 int
 buf_drain(int n)
+{
 	int size = 0, sz;
 	KASSERT(mutex_owned(&bufcache_lock));
 	while (size < n && bufmem > bufmem_lowater) {
 		sz = buf_trim();
 		if (sz <= 0)
 			break;
 		size += sz;
+	}
 	return size;
+}
 /*
  * Wait for operations on the buffer to complete.
  * When they do, extract and return the I/O's error value.
  */
 int
 biowait(buf_t *bp)
+{
 	BIOHIST_FUNC(__func__);
 	KASSERT(ISSET(bp->b_cflags, BC_BUSY));
 	SDT_PROBE1(io, kernel, , wait__start, bp);
 	mutex_enter(bp->b_objlock);
 	BIOHIST_CALLARGS(biohist, "bp=%#jx, oflags=0x%jx, ret_addr=%#jx",
 	    (uintptr_t)bp, bp->b_oflags,
 	    (uintptr_t)__builtin_return_address(0), 0);
 	while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI)) {
 		BIOHIST_LOG(biohist, "waiting bp=%#jx", (uintptr_t)bp, 0, 0, 0);
 		cv_wait(&bp->b_done, bp->b_objlock);
+	}
 	mutex_exit(bp->b_objlock);
 	SDT_PROBE1(io, kernel, , wait__done, bp);
 	BIOHIST_LOG(biohist, "return %jd", bp->b_error, 0, 0, 0);
 	return bp->b_error;
+}
 /*
  * Mark I/O complete on a buffer.
+ *
  * If a callback has been requested, e.g. the pageout
  * daemon, do so. Otherwise, awaken waiting processes.
+ *
  * [ Leffler, et al., says on p.247:
  *	"This routine wakes up the blocked process, frees the buffer
  *	for an asynchronous write, or, for a request by the pagedaemon
  *	process, invokes a procedure specified in the buffer structure" ]
+ *
  * In real life, the pagedaemon (or other system processes) wants
  * to do async stuff too, and doesn't want the buffer brelse()'d.
  * (for swap pager, that puts swap buffers on the free lists (!!!),
  * for the vn device, that puts allocated buffers on the free lists!)
  */
 void
 biodone(buf_t *bp)
+{
 	int s;
 	BIOHIST_FUNC(__func__);
 	KASSERT(!ISSET(bp->b_oflags, BO_DONE));
 	if (cpu_intr_p()) {
 		/* From interrupt mode: defer to a soft interrupt. */
 		s = splvm();
 		TAILQ_INSERT_TAIL(&curcpu()->ci_data.cpu_biodone, bp, b_actq);
 		BIOHIST_CALLARGS(biohist, "bp=%#jx, softint scheduled",
 		    (uintptr_t)bp, 0, 0, 0);
 		softint_schedule(biodone_sih);
 		splx(s);
 	} else {
 		/* Process now - the buffer may be freed soon. */
 		biodone2(bp);
+	}
+}
 SDT_PROBE_DEFINE1(io, kernel, , done, "struct buf *"/*bp*/);
 static void
 biodone2(buf_t *bp)
+{
 	void (*callout)(buf_t *);
 	SDT_PROBE1(io, kernel, ,done, bp);
 	BIOHIST_FUNC(__func__);
 	BIOHIST_CALLARGS(biohist, "bp=%#jx", (uintptr_t)bp, 0, 0, 0);
 	mutex_enter(bp->b_objlock);
 	/* Note that the transfer is done. */
 	if (ISSET(bp->b_oflags, BO_DONE))
 		panic("biodone2 already");
 	CLR(bp->b_flags, B_COWDONE);
 	SET(bp->b_oflags, BO_DONE);
 	BIO_SETPRIO(bp, BPRIO_DEFAULT);
 	/* Wake up waiting writers. */
 	if (!ISSET(bp->b_flags, B_READ))
 		vwakeup(bp);
 	if ((callout = bp->b_iodone) != NULL) {
 		BIOHIST_LOG(biohist, "callout %#jx", (uintptr_t)callout,
 , 0, 0);
 		/* Note callout done, then call out. */
 		KASSERT(!cv_has_waiters(&bp->b_done));
 		bp->b_iodone = NULL;
 		mutex_exit(bp->b_objlock);
 		(*callout)(bp);
 	} else if (ISSET(bp->b_flags, B_ASYNC)) {
 		/* If async, release. */
 		BIOHIST_LOG(biohist, "async", 0, 0, 0, 0);
 		KASSERT(!cv_has_waiters(&bp->b_done));
 		mutex_exit(bp->b_objlock);
 		brelse(bp, 0);
 	} else {
 		/* Otherwise just wake up waiters in biowait(). */
 		BIOHIST_LOG(biohist, "wake-up", 0, 0, 0, 0);
 		cv_broadcast(&bp->b_done);
 		mutex_exit(bp->b_objlock);
+	}
+}
 static void
 biointr(void *cookie)
+{
 	struct cpu_info *ci;
 	buf_t *bp;
 	int s;
 	BIOHIST_FUNC(__func__); BIOHIST_CALLED(biohist);
 	ci = curcpu();
 	s = splvm();
 	while (!TAILQ_EMPTY(&ci->ci_data.cpu_biodone)) {
 		KASSERT(curcpu() == ci);
 		bp = TAILQ_FIRST(&ci->ci_data.cpu_biodone);
 		TAILQ_REMOVE(&ci->ci_data.cpu_biodone, bp, b_actq);
 		splx(s);
 		BIOHIST_LOG(biohist, "bp=%#jx", (uintptr_t)bp, 0, 0, 0);
 		biodone2(bp);
 		s = splvm();
+	}
 	splx(s);
+}
 static void
 sysctl_fillbuf(const buf_t *i, struct buf_sysctl *o)
+{
 	const bool allowaddr = get_expose_address(curproc);
 	memset(o, 0, sizeof(*o));
 	o->b_flags = i->b_flags | i->b_cflags | i->b_oflags;
 	o->b_error = i->b_error;
 	o->b_prio = i->b_prio;
 	o->b_dev = i->b_dev;
 	o->b_bufsize = i->b_bufsize;
 	o->b_bcount = i->b_bcount;
 	o->b_resid = i->b_resid;
 	COND_SET_VALUE(o->b_addr, PTRTOUINT64(i->b_data), allowaddr);
 	o->b_blkno = i->b_blkno;
 	o->b_rawblkno = i->b_rawblkno;
 	COND_SET_VALUE(o->b_iodone, PTRTOUINT64(i->b_iodone), allowaddr);
 	COND_SET_VALUE(o->b_proc, PTRTOUINT64(i->b_proc), allowaddr);
 	COND_SET_VALUE(o->b_vp, PTRTOUINT64(i->b_vp), allowaddr);
 	COND_SET_VALUE(o->b_saveaddr, PTRTOUINT64(i->b_saveaddr), allowaddr);
 	o->b_lblkno = i->b_lblkno;
+}
 #define KERN_BUFSLOP 20
 static int
 sysctl_dobuf(SYSCTLFN_ARGS)
+{
 	buf_t *bp;
 	struct buf_sysctl bs;
 	struct bqueue *bq;
 	char *dp;
 	u_int i, op, arg;
 	size_t len, needed, elem_size, out_size;
 	int error, elem_count, retries;
 	if (namelen == 1 && name[0] == CTL_QUERY)
 		return (sysctl_query(SYSCTLFN_CALL(rnode)));
 	if (namelen != 4)
 		return (EINVAL);
 	retries = 100;
  retry:
 	dp = oldp;
 	len = (oldp != NULL) ? *oldlenp : 0;
 	op = name[0];
 	arg = name[1];
 	elem_size = name[2];
 	elem_count = name[3];
 	out_size = MIN(sizeof(bs), elem_size);
 	/*
 	 * at the moment, these are just "placeholders" to make the
 	 * API for retrieving kern.buf data more extensible in the
 	 * future.
+	 *
 	 * XXX kern.buf currently has "netbsd32" issues.  hopefully
 	 * these will be resolved at a later point.
 	 */
 	if (op != KERN_BUF_ALL || arg != KERN_BUF_ALL ||
 	    elem_size < 1 || elem_count < 0)
 		return (EINVAL);
 	error = 0;
 	needed = 0;
 	sysctl_unlock();
 	mutex_enter(&bufcache_lock);
 	for (i = 0; i < BQUEUES; i++) {
 		bq = &bufqueues[i];
 		TAILQ_FOREACH(bp, &bq->bq_queue, b_freelist) {
 			bq->bq_marker = bp;
 			if (len >= elem_size && elem_count > 0) {
 				sysctl_fillbuf(bp, &bs);
 				mutex_exit(&bufcache_lock);
 				error = copyout(&bs, dp, out_size);
 				mutex_enter(&bufcache_lock);
 				if (error)
 					break;
 				if (bq->bq_marker != bp) {
 					/*
 					 * This sysctl node is only for
 					 * statistics.  Retry; if the
 					 * queue keeps changing, then
 					 * bail out.
 					 */
 					if (retries-- == 0) {
 						error = EAGAIN;
 						break;
+					}
 					mutex_exit(&bufcache_lock);
 					sysctl_relock();
 					goto retry;
+				}
 				dp += elem_size;
 				len -= elem_size;
+			}
 			needed += elem_size;
 			if (elem_count > 0 && elem_count != INT_MAX)
 				elem_count--;
+		}
 		if (error != 0)
 			break;
+	}
 	mutex_exit(&bufcache_lock);
 	sysctl_relock();
 	*oldlenp = needed;
 	if (oldp == NULL)
 		*oldlenp += KERN_BUFSLOP * sizeof(buf_t);
 	return (error);
+}
 static int
 sysctl_bufvm_update(SYSCTLFN_ARGS)
+{
 	int error, rv;
 	struct sysctlnode node;
 	unsigned int temp_bufcache;
 	unsigned long temp_water;
 	/* Take a copy of the supplied node and its data */
 	node = *rnode;
 	if (node.sysctl_data == &bufcache) {
 	    node.sysctl_data = &temp_bufcache;
 	    temp_bufcache = *(unsigned int *)rnode->sysctl_data;
 	} else {
 	    node.sysctl_data = &temp_water;
 	    temp_water = *(unsigned long *)rnode->sysctl_data;
+	}
 	/* Update the copy */
 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
 	if (error || newp == NULL)
 		return (error);
 	if (rnode->sysctl_data == &bufcache) {
 		if (temp_bufcache > 100)
 			return (EINVAL);
 		bufcache = temp_bufcache;
 		buf_setwm();
 	} else if (rnode->sysctl_data == &bufmem_lowater) {
 		if (bufmem_hiwater - temp_water < 16)
 			return (EINVAL);
 		bufmem_lowater = temp_water;
 	} else if (rnode->sysctl_data == &bufmem_hiwater) {
 		if (temp_water - bufmem_lowater < 16)
 			return (EINVAL);
 		bufmem_hiwater = temp_water;
 	} else
 		return (EINVAL);
 	/* Drain until below new high water mark */
 	sysctl_unlock();
 	mutex_enter(&bufcache_lock);
 	while (bufmem > bufmem_hiwater) {
 		rv = buf_drain((bufmem - bufmem_hiwater) / (2 * 1024));
 		if (rv <= 0)
 			break;
+	}
 	mutex_exit(&bufcache_lock);
 	sysctl_relock();
 	return 0;
+}
 static struct sysctllog *vfsbio_sysctllog;
 static void
 sysctl_kern_buf_setup(void)
+{
 	sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL,
 		       CTLFLAG_PERMANENT,
 		       CTLTYPE_NODE, "buf",
 		       SYSCTL_DESCR("Kernel buffer cache information"),
 		       sysctl_dobuf, 0, NULL, 0,
 		       CTL_KERN, KERN_BUF, CTL_EOL);
+}
 static void
 sysctl_vm_buf_setup(void)
+{
 	sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL,
 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 		       CTLTYPE_INT, "bufcache",
 		       SYSCTL_DESCR("Percentage of physical memory to use for "
 				    "buffer cache"),
 		       sysctl_bufvm_update, 0, &bufcache, 0,
 		       CTL_VM, CTL_CREATE, CTL_EOL);
 	sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL,
 		       CTLFLAG_PERMANENT|CTLFLAG_READONLY,
 		       CTLTYPE_LONG, "bufmem",
 		       SYSCTL_DESCR("Amount of kernel memory used by buffer "
 				    "cache"),
 		       NULL, 0, &bufmem, 0,
 		       CTL_VM, CTL_CREATE, CTL_EOL);
 	sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL,
 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 		       CTLTYPE_LONG, "bufmem_lowater",
 		       SYSCTL_DESCR("Minimum amount of kernel memory to "
 				    "reserve for buffer cache"),
 		       sysctl_bufvm_update, 0, &bufmem_lowater, 0,
 		       CTL_VM, CTL_CREATE, CTL_EOL);
 	sysctl_createv(&vfsbio_sysctllog, 0, NULL, NULL,
 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 		       CTLTYPE_LONG, "bufmem_hiwater",
 		       SYSCTL_DESCR("Maximum amount of kernel memory to use "
 				    "for buffer cache"),
 		       sysctl_bufvm_update, 0, &bufmem_hiwater, 0,
 		       CTL_VM, CTL_CREATE, CTL_EOL);
+}
 static int
 bufhash_stats(struct hashstat_sysctl *hs, bool fill)
+{
 	buf_t *bp;
 	uint64_t chain;
 	strlcpy(hs->hash_name, "bufhash", sizeof(hs->hash_name));
 	strlcpy(hs->hash_desc, "buffer hash", sizeof(hs->hash_desc));
 	if (!fill)
 		return 0;
 	hs->hash_size = bufhash + 1;
 	for (size_t i = 0; i < hs->hash_size; i++) {
 		chain = 0;
 		mutex_enter(&bufcache_lock);
 		LIST_FOREACH(bp, &bufhashtbl[i], b_hash) {
 			chain++;
+		}
 		mutex_exit(&bufcache_lock);
 		if (chain > 0) {
 			hs->hash_used++;
 			hs->hash_items += chain;
 			if (chain > hs->hash_maxchain)
 				hs->hash_maxchain = chain;
+		}
 		preempt_point();
+	}
 	return 0;
+}
 #ifdef DEBUG
 /*
  * Print out statistics on the current allocation of the buffer pool.
  * Can be enabled to print out on every ``sync'' by setting "syncprt"
  * in vfs_syscalls.c using sysctl.
  */
 void
 vfs_bufstats(void)
+{
 	int i, j, count;
 	buf_t *bp;
 	struct bqueue *dp;
 	int counts[MAXBSIZE / MIN_PAGE_SIZE + 1];
 	static const char *bname[BQUEUES] = { "LOCKED", "LRU", "AGE" };
 	for (dp = bufqueues, i = 0; dp < &bufqueues[BQUEUES]; dp++, i++) {
 		count = 0;
 		memset(counts, 0, sizeof(counts));
 		TAILQ_FOREACH(bp, &dp->bq_queue, b_freelist) {
 			counts[bp->b_bufsize / PAGE_SIZE]++;
 			count++;
+		}
 		printf("%s: total-%d", bname[i], count);
 		for (j = 0; j <= MAXBSIZE / PAGE_SIZE; j++)
 			if (counts[j] != 0)
 				printf(", %d-%d", j * PAGE_SIZE, counts[j]);
 		printf("\n");
+	}
+}
 #endif /* DEBUG */
 /* ------------------------------ */
 buf_t *
 getiobuf(struct vnode *vp, bool waitok)
+{
 	buf_t *bp;
 	bp = pool_cache_get(bufio_cache, (waitok ? PR_WAITOK : PR_NOWAIT));
 	if (bp == NULL)
 		return bp;
 	buf_init(bp);
 	if ((bp->b_vp = vp) != NULL) {
 		bp->b_objlock = vp->v_interlock;
 	} else {
 		KASSERT(bp->b_objlock == &buffer_lock);
+	}
 	return bp;
+}
 void
 putiobuf(buf_t *bp)
+{
 	buf_destroy(bp);
 	pool_cache_put(bufio_cache, bp);
+}
 /*
  * nestiobuf_iodone: b_iodone callback for nested buffers.
  */
 void
 nestiobuf_iodone(buf_t *bp)
+{
 	buf_t *mbp = bp->b_private;
 	int error;
 	int donebytes;
 	KASSERT(bp->b_bcount <= bp->b_bufsize);
 	KASSERT(mbp != bp);
 	error = bp->b_error;
 	if (bp->b_error == 0 &&
 	    (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) {
 		/*
 		 * Not all got transferred, raise an error. We have no way to
 		 * propagate these conditions to mbp.
 		 */
 		error = EIO;
+	}
 	donebytes = bp->b_bufsize;
 	putiobuf(bp);
 	nestiobuf_done(mbp, donebytes, error);
+}
 /*
  * nestiobuf_setup: setup a "nested" buffer.
+ *
  * => 'mbp' is a "master" buffer which is being divided into sub pieces.
  * => 'bp' should be a buffer allocated by getiobuf.
  * => 'offset' is a byte offset in the master buffer.
  * => 'size' is a size in bytes of this nested buffer.
  */
 void
 nestiobuf_setup(buf_t *mbp, buf_t *bp, int offset, size_t size)
+{
 	const int b_pass = mbp->b_flags & (B_READ|B_PHYS|B_RAW|B_MEDIA_FLAGS);
 	struct vnode *vp = mbp->b_vp;
 	KASSERT(mbp->b_bcount >= offset + size);
 	bp->b_vp = vp;
 	bp->b_dev = mbp->b_dev;
 	bp->b_objlock = mbp->b_objlock;
 	bp->b_cflags = BC_BUSY;
 	bp->b_flags = B_ASYNC | b_pass;
 	bp->b_iodone = nestiobuf_iodone;
 	bp->b_data = (char *)mbp->b_data + offset;
 	bp->b_resid = bp->b_bcount = size;
 	bp->b_bufsize = bp->b_bcount;
 	bp->b_private = mbp;
 	BIO_COPYPRIO(bp, mbp);
 	if (BUF_ISWRITE(bp) && vp != NULL) {
 		mutex_enter(vp->v_interlock);
 		vp->v_numoutput++;
 		mutex_exit(vp->v_interlock);
+	}
+}
 /*
  * nestiobuf_done: propagate completion to the master buffer.
+ *
  * => 'donebytes' specifies how many bytes in the 'mbp' is completed.
  * => 'error' is an errno(2) that 'donebytes' has been completed with.
  */
 void
 nestiobuf_done(buf_t *mbp, int donebytes, int error)
+{
 	if (donebytes == 0) {
 		return;
+	}
 	mutex_enter(mbp->b_objlock);
 	KASSERT(mbp->b_resid >= donebytes);
 	mbp->b_resid -= donebytes;
 	if (error)
 		mbp->b_error = error;
 	if (mbp->b_resid == 0) {
 		if (mbp->b_error)
 			mbp->b_resid = mbp->b_bcount;
 		mutex_exit(mbp->b_objlock);
 		biodone(mbp);
 	} else
 		mutex_exit(mbp->b_objlock);
+}
 void
 buf_init(buf_t *bp)
+{
 	cv_init(&bp->b_busy, "biolock");
 	cv_init(&bp->b_done, "biowait");
 	bp->b_dev = NODEV;
 	bp->b_error = 0;
 	bp->b_flags = 0;
 	bp->b_cflags = 0;
 	bp->b_oflags = 0;
 	bp->b_objlock = &buffer_lock;
 	bp->b_iodone = NULL;
 	bp->b_dev = NODEV;
 	bp->b_vnbufs.le_next = NOLIST;
 	BIO_SETPRIO(bp, BPRIO_DEFAULT);
+}
 void
 buf_destroy(buf_t *bp)
+{
 	cv_destroy(&bp->b_done);
 	cv_destroy(&bp->b_busy);
+}
 int
 bbusy(buf_t *bp, bool intr, int timo, kmutex_t *interlock)
+{
 	int error;
 	KASSERT(mutex_owned(&bufcache_lock));
 	SDT_PROBE4(io, kernel, , bbusy__start,  bp, intr, timo, interlock);
 	if ((bp->b_cflags & BC_BUSY) != 0) {
 		if (curlwp == uvm.pagedaemon_lwp) {
 			error = EDEADLK;
 			goto out;
+		}
 		bp->b_cflags |= BC_WANTED;
 		if (interlock != NULL)
 			mutex_exit(interlock);
 		if (intr) {
 			error = cv_timedwait_sig(&bp->b_busy, &bufcache_lock,
 			    timo);
 		} else {
 			error = cv_timedwait(&bp->b_busy, &bufcache_lock,
 			    timo);
+		}
 		/*
 		 * At this point the buffer may be gone: don't touch it
 		 * again.  The caller needs to find it again and retry.
 		 */
 		if (interlock != NULL)
 			mutex_enter(interlock);
 		if (error == 0)
 			error = EPASSTHROUGH;
 	} else {
 		bp->b_cflags |= BC_BUSY;
 		error = 0;
+	}
 out:	SDT_PROBE5(io, kernel, , bbusy__done,
 	    bp, intr, timo, interlock, error);
 	return error;
+}
 /*
  * Nothing outside this file should really need to know about nbuf,
  * but a few things still want to read it, so give them a way to do that.
  */
 u_int
 buf_nbuf(void)
+{
 	return nbuf;
+}