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lfs_subr.c revision 1.96
      1 /*	$NetBSD: lfs_subr.c,v 1.96 2017/07/26 14:38:59 maya Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1999, 2000, 2001, 2002, 2003 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Konrad E. Schroder <perseant (at) hhhh.org>.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 /*
     32  * Copyright (c) 1991, 1993
     33  *	The Regents of the University of California.  All rights reserved.
     34  *
     35  * Redistribution and use in source and binary forms, with or without
     36  * modification, are permitted provided that the following conditions
     37  * are met:
     38  * 1. Redistributions of source code must retain the above copyright
     39  *    notice, this list of conditions and the following disclaimer.
     40  * 2. Redistributions in binary form must reproduce the above copyright
     41  *    notice, this list of conditions and the following disclaimer in the
     42  *    documentation and/or other materials provided with the distribution.
     43  * 3. Neither the name of the University nor the names of its contributors
     44  *    may be used to endorse or promote products derived from this software
     45  *    without specific prior written permission.
     46  *
     47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     57  * SUCH DAMAGE.
     58  *
     59  *	@(#)lfs_subr.c	8.4 (Berkeley) 5/8/95
     60  */
     61 
     62 #include <sys/cdefs.h>
     63 __KERNEL_RCSID(0, "$NetBSD: lfs_subr.c,v 1.96 2017/07/26 14:38:59 maya Exp $");
     64 
     65 #include <sys/param.h>
     66 #include <sys/systm.h>
     67 #include <sys/namei.h>
     68 #include <sys/vnode.h>
     69 #include <sys/buf.h>
     70 #include <sys/mount.h>
     71 #include <sys/malloc.h>
     72 #include <sys/proc.h>
     73 #include <sys/kauth.h>
     74 
     75 #include <ufs/lfs/ulfs_inode.h>
     76 #include <ufs/lfs/lfs.h>
     77 #include <ufs/lfs/lfs_accessors.h>
     78 #include <ufs/lfs/lfs_kernel.h>
     79 #include <ufs/lfs/lfs_extern.h>
     80 
     81 #include <uvm/uvm.h>
     82 
     83 #ifdef DEBUG
     84 const char *lfs_res_names[LFS_NB_COUNT] = {
     85 	"summary",
     86 	"superblock",
     87 	"file block",
     88 	"cluster",
     89 	"clean",
     90 	"blkiov",
     91 };
     92 #endif
     93 
     94 int lfs_res_qty[LFS_NB_COUNT] = {
     95 	LFS_N_SUMMARIES,
     96 	LFS_N_SBLOCKS,
     97 	LFS_N_IBLOCKS,
     98 	LFS_N_CLUSTERS,
     99 	LFS_N_CLEAN,
    100 	LFS_N_BLKIOV,
    101 };
    102 
    103 void
    104 lfs_setup_resblks(struct lfs *fs)
    105 {
    106 	int i, j;
    107 	int maxbpp;
    108 
    109 	ASSERT_NO_SEGLOCK(fs);
    110 	fs->lfs_resblk = malloc(LFS_N_TOTAL * sizeof(res_t), M_SEGMENT,
    111 				M_WAITOK);
    112 	for (i = 0; i < LFS_N_TOTAL; i++) {
    113 		fs->lfs_resblk[i].inuse = 0;
    114 		fs->lfs_resblk[i].p = NULL;
    115 	}
    116 	for (i = 0; i < LFS_RESHASH_WIDTH; i++)
    117 		LIST_INIT(fs->lfs_reshash + i);
    118 
    119 	/*
    120 	 * These types of allocations can be larger than a page,
    121 	 * so we can't use the pool subsystem for them.
    122 	 */
    123 	for (i = 0, j = 0; j < LFS_N_SUMMARIES; j++, i++)
    124 		fs->lfs_resblk[i].size = lfs_sb_getsumsize(fs);
    125 	for (j = 0; j < LFS_N_SBLOCKS; j++, i++)
    126 		fs->lfs_resblk[i].size = LFS_SBPAD;
    127 	for (j = 0; j < LFS_N_IBLOCKS; j++, i++)
    128 		fs->lfs_resblk[i].size = lfs_sb_getbsize(fs);
    129 	for (j = 0; j < LFS_N_CLUSTERS; j++, i++)
    130 		fs->lfs_resblk[i].size = MAXPHYS;
    131 	for (j = 0; j < LFS_N_CLEAN; j++, i++)
    132 		fs->lfs_resblk[i].size = MAXPHYS;
    133 	for (j = 0; j < LFS_N_BLKIOV; j++, i++)
    134 		fs->lfs_resblk[i].size = LFS_MARKV_MAXBLKCNT * sizeof(BLOCK_INFO);
    135 
    136 	for (i = 0; i < LFS_N_TOTAL; i++) {
    137 		fs->lfs_resblk[i].p = malloc(fs->lfs_resblk[i].size,
    138 					     M_SEGMENT, M_WAITOK);
    139 	}
    140 
    141 	/*
    142 	 * Initialize pools for small types (XXX is BPP small?)
    143 	 */
    144 	pool_init(&fs->lfs_clpool, sizeof(struct lfs_cluster), 0, 0, 0,
    145 		"lfsclpl", &pool_allocator_nointr, IPL_NONE);
    146 	pool_init(&fs->lfs_segpool, sizeof(struct segment), 0, 0, 0,
    147 		"lfssegpool", &pool_allocator_nointr, IPL_NONE);
    148 	/* XXX: should this int32 be 32/64? */
    149 	maxbpp = ((lfs_sb_getsumsize(fs) - SEGSUM_SIZE(fs)) / sizeof(int32_t) + 2);
    150 	maxbpp = MIN(maxbpp, lfs_segsize(fs) / lfs_sb_getfsize(fs) + 2);
    151 	pool_init(&fs->lfs_bpppool, maxbpp * sizeof(struct buf *), 0, 0, 0,
    152 		"lfsbpppl", &pool_allocator_nointr, IPL_NONE);
    153 }
    154 
    155 void
    156 lfs_free_resblks(struct lfs *fs)
    157 {
    158 	int i;
    159 
    160 	pool_destroy(&fs->lfs_bpppool);
    161 	pool_destroy(&fs->lfs_segpool);
    162 	pool_destroy(&fs->lfs_clpool);
    163 
    164 	mutex_enter(&lfs_lock);
    165 	for (i = 0; i < LFS_N_TOTAL; i++) {
    166 		while (fs->lfs_resblk[i].inuse)
    167 			mtsleep(&fs->lfs_resblk, PRIBIO + 1, "lfs_free", 0,
    168 				&lfs_lock);
    169 		if (fs->lfs_resblk[i].p != NULL)
    170 			free(fs->lfs_resblk[i].p, M_SEGMENT);
    171 	}
    172 	free(fs->lfs_resblk, M_SEGMENT);
    173 	mutex_exit(&lfs_lock);
    174 }
    175 
    176 static unsigned int
    177 lfs_mhash(void *vp)
    178 {
    179 	return (unsigned int)(((unsigned long)vp) >> 2) % LFS_RESHASH_WIDTH;
    180 }
    181 
    182 /*
    183  * Return memory of the given size for the given purpose, or use one of a
    184  * number of spare last-resort buffers, if malloc returns NULL.
    185  */
    186 void *
    187 lfs_malloc(struct lfs *fs, size_t size, int type)
    188 {
    189 	struct lfs_res_blk *re;
    190 	void *r;
    191 	int i, start;
    192 	unsigned int h;
    193 
    194 	ASSERT_MAYBE_SEGLOCK(fs);
    195 	r = NULL;
    196 
    197 	/* If no mem allocated for this type, it just waits */
    198 	if (lfs_res_qty[type] == 0) {
    199 		r = malloc(size, M_SEGMENT, M_WAITOK);
    200 		return r;
    201 	}
    202 
    203 	/* Otherwise try a quick malloc, and if it works, great */
    204 	if ((r = malloc(size, M_SEGMENT, M_NOWAIT)) != NULL) {
    205 		return r;
    206 	}
    207 
    208 	/*
    209 	 * If malloc returned NULL, we are forced to use one of our
    210 	 * reserve blocks.  We have on hand at least one summary block,
    211 	 * at least one cluster block, at least one superblock,
    212 	 * and several indirect blocks.
    213 	 */
    214 
    215 	mutex_enter(&lfs_lock);
    216 	/* skip over blocks of other types */
    217 	for (i = 0, start = 0; i < type; i++)
    218 		start += lfs_res_qty[i];
    219 	while (r == NULL) {
    220 		for (i = 0; i < lfs_res_qty[type]; i++) {
    221 			if (fs->lfs_resblk[start + i].inuse == 0) {
    222 				re = fs->lfs_resblk + start + i;
    223 				re->inuse = 1;
    224 				r = re->p;
    225 				KASSERT(re->size >= size);
    226 				h = lfs_mhash(r);
    227 				LIST_INSERT_HEAD(&fs->lfs_reshash[h], re, res);
    228 				mutex_exit(&lfs_lock);
    229 				return r;
    230 			}
    231 		}
    232 		DLOG((DLOG_MALLOC, "sleeping on %s (%d)\n",
    233 		      lfs_res_names[type], lfs_res_qty[type]));
    234 		mtsleep(&fs->lfs_resblk, PVM, "lfs_malloc", 0,
    235 			&lfs_lock);
    236 		DLOG((DLOG_MALLOC, "done sleeping on %s\n",
    237 		      lfs_res_names[type]));
    238 	}
    239 	/* NOTREACHED */
    240 	mutex_exit(&lfs_lock);
    241 	return r;
    242 }
    243 
    244 void
    245 lfs_free(struct lfs *fs, void *p, int type)
    246 {
    247 	unsigned int h;
    248 	res_t *re;
    249 
    250 	ASSERT_MAYBE_SEGLOCK(fs);
    251 	h = lfs_mhash(p);
    252 	mutex_enter(&lfs_lock);
    253 	LIST_FOREACH(re, &fs->lfs_reshash[h], res) {
    254 		if (re->p == p) {
    255 			KASSERT(re->inuse == 1);
    256 			LIST_REMOVE(re, res);
    257 			re->inuse = 0;
    258 			wakeup(&fs->lfs_resblk);
    259 			mutex_exit(&lfs_lock);
    260 			return;
    261 		}
    262 	}
    263 
    264 #ifdef notyet /* XXX this assert fires */
    265 	for (int i = 0; i < LFS_N_TOTAL; i++) {
    266 		KDASSERTMSG(fs->lfs_resblk[i].p == p,
    267 		    "lfs_free: inconsistent reserved block");
    268 	}
    269 #endif
    270 
    271 	mutex_exit(&lfs_lock);
    272 
    273 	/*
    274 	 * If we didn't find it, free it.
    275 	 */
    276 	free(p, M_SEGMENT);
    277 }
    278 
    279 /*
    280  * lfs_seglock --
    281  *	Single thread the segment writer.
    282  */
    283 int
    284 lfs_seglock(struct lfs *fs, unsigned long flags)
    285 {
    286 	struct segment *sp;
    287 
    288 	mutex_enter(&lfs_lock);
    289 	if (fs->lfs_seglock) {
    290 		if (fs->lfs_lockpid == curproc->p_pid &&
    291 		    fs->lfs_locklwp == curlwp->l_lid) {
    292 			++fs->lfs_seglock;
    293 			fs->lfs_sp->seg_flags |= flags;
    294 			mutex_exit(&lfs_lock);
    295 			return 0;
    296 		} else if (flags & SEGM_PAGEDAEMON) {
    297 			mutex_exit(&lfs_lock);
    298 			return EWOULDBLOCK;
    299 		} else {
    300 			while (fs->lfs_seglock) {
    301 				(void)mtsleep(&fs->lfs_seglock, PRIBIO + 1,
    302 					"lfs_seglock", 0, &lfs_lock);
    303 			}
    304 		}
    305 	}
    306 
    307 	fs->lfs_seglock = 1;
    308 	fs->lfs_lockpid = curproc->p_pid;
    309 	fs->lfs_locklwp = curlwp->l_lid;
    310 	mutex_exit(&lfs_lock);
    311 	fs->lfs_cleanind = 0;
    312 
    313 	LFS_ENTER_LOG("seglock", __FILE__, __LINE__, 0, flags, curproc->p_pid);
    314 
    315 	/* Drain fragment size changes out */
    316 	rw_enter(&fs->lfs_fraglock, RW_WRITER);
    317 
    318 	sp = fs->lfs_sp = pool_get(&fs->lfs_segpool, PR_WAITOK);
    319 	sp->bpp = pool_get(&fs->lfs_bpppool, PR_WAITOK);
    320 	sp->seg_flags = flags;
    321 	sp->vp = NULL;
    322 	sp->seg_iocount = 0;
    323 	(void) lfs_initseg(fs);
    324 
    325 	/*
    326 	 * Keep a cumulative count of the outstanding I/O operations.  If the
    327 	 * disk drive catches up with us it could go to zero before we finish,
    328 	 * so we artificially increment it by one until we've scheduled all of
    329 	 * the writes we intend to do.
    330 	 */
    331 	mutex_enter(&lfs_lock);
    332 	++fs->lfs_iocount;
    333 	fs->lfs_startseg = lfs_sb_getcurseg(fs);
    334 	mutex_exit(&lfs_lock);
    335 	return 0;
    336 }
    337 
    338 static void lfs_unmark_dirop(struct lfs *);
    339 
    340 static void
    341 lfs_unmark_dirop(struct lfs *fs)
    342 {
    343 	struct inode *ip, *nip;
    344 	struct vnode *vp;
    345 	int doit;
    346 
    347 	ASSERT_NO_SEGLOCK(fs);
    348 	mutex_enter(&lfs_lock);
    349 	doit = !(fs->lfs_flags & LFS_UNDIROP);
    350 	if (doit)
    351 		fs->lfs_flags |= LFS_UNDIROP;
    352 	if (!doit) {
    353 		mutex_exit(&lfs_lock);
    354 		return;
    355 	}
    356 
    357 	for (ip = TAILQ_FIRST(&fs->lfs_dchainhd); ip != NULL; ip = nip) {
    358 		nip = TAILQ_NEXT(ip, i_lfs_dchain);
    359 		vp = ITOV(ip);
    360 		if ((ip->i_state & (IN_ADIROP | IN_CDIROP)) == IN_CDIROP) {
    361 			--lfs_dirvcount;
    362 			--fs->lfs_dirvcount;
    363 			vp->v_uflag &= ~VU_DIROP;
    364 			TAILQ_REMOVE(&fs->lfs_dchainhd, ip, i_lfs_dchain);
    365 			wakeup(&lfs_dirvcount);
    366 			fs->lfs_unlockvp = vp;
    367 			mutex_exit(&lfs_lock);
    368 			vrele(vp);
    369 			mutex_enter(&lfs_lock);
    370 			fs->lfs_unlockvp = NULL;
    371 			ip->i_state &= ~IN_CDIROP;
    372 		}
    373 	}
    374 
    375 	fs->lfs_flags &= ~LFS_UNDIROP;
    376 	wakeup(&fs->lfs_flags);
    377 	mutex_exit(&lfs_lock);
    378 }
    379 
    380 static void
    381 lfs_auto_segclean(struct lfs *fs)
    382 {
    383 	int i, error, waited;
    384 
    385 	ASSERT_SEGLOCK(fs);
    386 	/*
    387 	 * Now that we've swapped lfs_activesb, but while we still
    388 	 * hold the segment lock, run through the segment list marking
    389 	 * the empty ones clean.
    390 	 * XXX - do we really need to do them all at once?
    391 	 */
    392 	waited = 0;
    393 	for (i = 0; i < lfs_sb_getnseg(fs); i++) {
    394 		if ((fs->lfs_suflags[0][i] &
    395 		     (SEGUSE_ACTIVE | SEGUSE_DIRTY | SEGUSE_EMPTY)) ==
    396 		    (SEGUSE_DIRTY | SEGUSE_EMPTY) &&
    397 		    (fs->lfs_suflags[1][i] &
    398 		     (SEGUSE_ACTIVE | SEGUSE_DIRTY | SEGUSE_EMPTY)) ==
    399 		    (SEGUSE_DIRTY | SEGUSE_EMPTY)) {
    400 
    401 			/* Make sure the sb is written before we clean */
    402 			mutex_enter(&lfs_lock);
    403 			while (waited == 0 && fs->lfs_sbactive)
    404 				mtsleep(&fs->lfs_sbactive, PRIBIO+1, "lfs asb",
    405 					0, &lfs_lock);
    406 			mutex_exit(&lfs_lock);
    407 			waited = 1;
    408 
    409 			if ((error = lfs_do_segclean(fs, i)) != 0) {
    410 				DLOG((DLOG_CLEAN, "lfs_auto_segclean: lfs_do_segclean returned %d for seg %d\n", error, i));
    411 			}
    412 		}
    413 		fs->lfs_suflags[1 - fs->lfs_activesb][i] =
    414 			fs->lfs_suflags[fs->lfs_activesb][i];
    415 	}
    416 }
    417 
    418 /*
    419  * lfs_segunlock --
    420  *	Single thread the segment writer.
    421  */
    422 void
    423 lfs_segunlock(struct lfs *fs)
    424 {
    425 	struct segment *sp;
    426 	unsigned long sync, ckp;
    427 	struct buf *bp;
    428 	int do_unmark_dirop = 0;
    429 
    430 	sp = fs->lfs_sp;
    431 
    432 	mutex_enter(&lfs_lock);
    433 
    434 	if (!LFS_SEGLOCK_HELD(fs))
    435 		panic("lfs seglock not held");
    436 
    437 	if (fs->lfs_seglock == 1) {
    438 		if ((sp->seg_flags & (SEGM_PROT | SEGM_CLEAN)) == 0)
    439 			do_unmark_dirop = 1;
    440 		mutex_exit(&lfs_lock);
    441 		sync = sp->seg_flags & SEGM_SYNC;
    442 		ckp = sp->seg_flags & SEGM_CKP;
    443 
    444 		/* We should have a segment summary, and nothing else */
    445 		KASSERT(sp->cbpp == sp->bpp + 1);
    446 
    447 		/* Free allocated segment summary */
    448 		lfs_sb_suboffset(fs, lfs_btofsb(fs, lfs_sb_getsumsize(fs)));
    449 		bp = *sp->bpp;
    450 		lfs_freebuf(fs, bp);
    451 
    452 		pool_put(&fs->lfs_bpppool, sp->bpp);
    453 		sp->bpp = NULL;
    454 
    455 		/*
    456 		 * If we're not sync, we're done with sp, get rid of it.
    457 		 * Otherwise, we keep a local copy around but free
    458 		 * fs->lfs_sp so another process can use it (we have to
    459 		 * wait but they don't have to wait for us).
    460 		 */
    461 		if (!sync)
    462 			pool_put(&fs->lfs_segpool, sp);
    463 		fs->lfs_sp = NULL;
    464 
    465 		/*
    466 		 * If the I/O count is non-zero, sleep until it reaches zero.
    467 		 * At the moment, the user's process hangs around so we can
    468 		 * sleep.
    469 		 */
    470 		mutex_enter(&lfs_lock);
    471 		if (--fs->lfs_iocount <= 1)
    472 			wakeup(&fs->lfs_iocount);
    473 		mutex_exit(&lfs_lock);
    474 
    475 		/*
    476 		 * If we're not checkpointing, we don't have to block
    477 		 * other processes to wait for a synchronous write
    478 		 * to complete.
    479 		 */
    480 		if (!ckp) {
    481 			LFS_ENTER_LOG("segunlock_std", __FILE__, __LINE__, 0, 0, curproc->p_pid);
    482 
    483 			mutex_enter(&lfs_lock);
    484 			--fs->lfs_seglock;
    485 			fs->lfs_lockpid = 0;
    486 			fs->lfs_locklwp = 0;
    487 			mutex_exit(&lfs_lock);
    488 			wakeup(&fs->lfs_seglock);
    489 		}
    490 		/*
    491 		 * We let checkpoints happen asynchronously.  That means
    492 		 * that during recovery, we have to roll forward between
    493 		 * the two segments described by the first and second
    494 		 * superblocks to make sure that the checkpoint described
    495 		 * by a superblock completed.
    496 		 */
    497 		mutex_enter(&lfs_lock);
    498 		while (ckp && sync && fs->lfs_iocount) {
    499 			(void)mtsleep(&fs->lfs_iocount, PRIBIO + 1,
    500 				      "lfs_iocount", 0, &lfs_lock);
    501 			DLOG((DLOG_SEG, "sleeping on iocount %x == %d\n", fs, fs->lfs_iocount));
    502 		}
    503 		while (sync && sp->seg_iocount) {
    504 			(void)mtsleep(&sp->seg_iocount, PRIBIO + 1,
    505 				     "seg_iocount", 0, &lfs_lock);
    506 			DLOG((DLOG_SEG, "sleeping on iocount %x == %d\n", sp, sp->seg_iocount));
    507 		}
    508 		mutex_exit(&lfs_lock);
    509 		if (sync)
    510 			pool_put(&fs->lfs_segpool, sp);
    511 
    512 		if (ckp) {
    513 			fs->lfs_nactive = 0;
    514 			/* If we *know* everything's on disk, write both sbs */
    515 			/* XXX should wait for this one	 */
    516 			if (sync)
    517 				lfs_writesuper(fs, lfs_sb_getsboff(fs, fs->lfs_activesb));
    518 			lfs_writesuper(fs, lfs_sb_getsboff(fs, 1 - fs->lfs_activesb));
    519 			if (!(fs->lfs_ivnode->v_mount->mnt_iflag & IMNT_UNMOUNT)) {
    520 				lfs_auto_segclean(fs);
    521 				/* If sync, we can clean the remainder too */
    522 				if (sync)
    523 					lfs_auto_segclean(fs);
    524 			}
    525 			fs->lfs_activesb = 1 - fs->lfs_activesb;
    526 
    527 			LFS_ENTER_LOG("segunlock_ckp", __FILE__, __LINE__, 0, 0, curproc->p_pid);
    528 
    529 			mutex_enter(&lfs_lock);
    530 			--fs->lfs_seglock;
    531 			fs->lfs_lockpid = 0;
    532 			fs->lfs_locklwp = 0;
    533 			mutex_exit(&lfs_lock);
    534 			wakeup(&fs->lfs_seglock);
    535 		}
    536 		/* Reenable fragment size changes */
    537 		rw_exit(&fs->lfs_fraglock);
    538 		if (do_unmark_dirop)
    539 			lfs_unmark_dirop(fs);
    540 	} else {
    541 		--fs->lfs_seglock;
    542 		mutex_exit(&lfs_lock);
    543 	}
    544 }
    545 
    546 /*
    547  * Drain dirops and start writer.
    548  *
    549  * No simple_locks are held when we enter and none are held when we return.
    550  */
    551 int
    552 lfs_writer_enter(struct lfs *fs, const char *wmesg)
    553 {
    554 	int error = 0;
    555 
    556 	ASSERT_MAYBE_SEGLOCK(fs);
    557 	mutex_enter(&lfs_lock);
    558 
    559 	/* disallow dirops during flush */
    560 	fs->lfs_writer++;
    561 
    562 	while (fs->lfs_dirops > 0) {
    563 		++fs->lfs_diropwait;
    564 		error = mtsleep(&fs->lfs_writer, PRIBIO+1, wmesg, 0,
    565 				&lfs_lock);
    566 		--fs->lfs_diropwait;
    567 	}
    568 
    569 	if (error)
    570 		fs->lfs_writer--;
    571 
    572 	mutex_exit(&lfs_lock);
    573 
    574 	return error;
    575 }
    576 
    577 void
    578 lfs_writer_leave(struct lfs *fs)
    579 {
    580 	bool dowakeup;
    581 
    582 	ASSERT_MAYBE_SEGLOCK(fs);
    583 	mutex_enter(&lfs_lock);
    584 	dowakeup = !(--fs->lfs_writer);
    585 	if (dowakeup)
    586 		cv_broadcast(&fs->lfs_diropscv);
    587 	mutex_exit(&lfs_lock);
    588 }
    589 
    590 /*
    591  * Unlock, wait for the cleaner, then relock to where we were before.
    592  * To be used only at a fairly high level, to address a paucity of free
    593  * segments propagated back from lfs_gop_write().
    594  */
    595 void
    596 lfs_segunlock_relock(struct lfs *fs)
    597 {
    598 	int n = fs->lfs_seglock;
    599 	u_int16_t seg_flags;
    600 	CLEANERINFO *cip;
    601 	struct buf *bp;
    602 
    603 	if (n == 0)
    604 		return;
    605 
    606 	/* Write anything we've already gathered to disk */
    607 	lfs_writeseg(fs, fs->lfs_sp);
    608 
    609 	/* Tell cleaner */
    610 	LFS_CLEANERINFO(cip, fs, bp);
    611 	lfs_ci_setflags(fs, cip,
    612 			lfs_ci_getflags(fs, cip) | LFS_CLEANER_MUST_CLEAN);
    613 	LFS_SYNC_CLEANERINFO(cip, fs, bp, 1);
    614 
    615 	/* Save segment flags for later */
    616 	seg_flags = fs->lfs_sp->seg_flags;
    617 
    618 	fs->lfs_sp->seg_flags |= SEGM_PROT; /* Don't unmark dirop nodes */
    619 	while(fs->lfs_seglock)
    620 		lfs_segunlock(fs);
    621 
    622 	/* Wait for the cleaner */
    623 	lfs_wakeup_cleaner(fs);
    624 	mutex_enter(&lfs_lock);
    625 	while (LFS_STARVED_FOR_SEGS(fs))
    626 		mtsleep(&fs->lfs_availsleep, PRIBIO, "relock", 0,
    627 			&lfs_lock);
    628 	mutex_exit(&lfs_lock);
    629 
    630 	/* Put the segment lock back the way it was. */
    631 	while(n--)
    632 		lfs_seglock(fs, seg_flags);
    633 
    634 	/* Cleaner can relax now */
    635 	LFS_CLEANERINFO(cip, fs, bp);
    636 	lfs_ci_setflags(fs, cip,
    637 			lfs_ci_getflags(fs, cip) & ~LFS_CLEANER_MUST_CLEAN);
    638 	LFS_SYNC_CLEANERINFO(cip, fs, bp, 1);
    639 
    640 	return;
    641 }
    642 
    643 /*
    644  * Wake up the cleaner, provided that nowrap is not set.
    645  */
    646 void
    647 lfs_wakeup_cleaner(struct lfs *fs)
    648 {
    649 	if (fs->lfs_nowrap > 0)
    650 		return;
    651 
    652 	wakeup(&fs->lfs_nextsegsleep);
    653 	wakeup(&lfs_allclean_wakeup);
    654 }
    655