1 /*
2  * Copyright (c) 2013-2018 The DragonFly Project.  All rights reserved.
3  *
4  * This code is derived from software contributed to The DragonFly Project
5  * by Matthew Dillon <dillon@dragonflybsd.org>
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in
15  *    the documentation and/or other materials provided with the
16  *    distribution.
17  * 3. Neither the name of The DragonFly Project nor the names of its
18  *    contributors may be used to endorse or promote products derived
19  *    from this software without specific, prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/fcntl.h>
38 #include <sys/buf.h>
39 #include <sys/proc.h>
40 #include <sys/namei.h>
41 #include <sys/mount.h>
42 #include <sys/vnode.h>
43 #include <sys/mountctl.h>
44 #include <vm/vm_kern.h>
45 #include <vm/vm_extern.h>
46 
47 #include "hammer2.h"
48 
49 /*
50  * breadth-first search
51  */
52 typedef struct hammer2_chain_save {
53 	TAILQ_ENTRY(hammer2_chain_save)	entry;
54 	hammer2_chain_t	*chain;
55 	int pri;
56 } hammer2_chain_save_t;
57 
58 TAILQ_HEAD(hammer2_chain_save_list, hammer2_chain_save);
59 typedef struct hammer2_chain_save_list hammer2_chain_save_list_t;
60 
61 typedef struct hammer2_bulkfree_info {
62 	hammer2_dev_t		*hmp;
63 	kmem_anon_desc_t	kp;
64 	hammer2_off_t		sbase;		/* sub-loop iteration */
65 	hammer2_off_t		sstop;
66 	hammer2_bmap_data_t	*bmap;
67 	int			depth;
68 	long			count_10_00;	/* staged->free	     */
69 	long			count_11_10;	/* allocated->staged */
70 	long			count_00_11;	/* (should not happen) */
71 	long			count_01_11;	/* (should not happen) */
72 	long			count_10_11;	/* staged->allocated */
73 	long			count_l0cleans;
74 	long			count_linadjusts;
75 	long			count_inodes_scanned;
76 	long			count_dirents_scanned;
77 	long			count_dedup_factor;
78 	long			count_bytes_scanned;
79 	long			count_chains_scanned;
80 	long			count_chains_reported;
81 	long			bulkfree_calls;
82 	int			bulkfree_ticks;
83 	hammer2_off_t		adj_free;
84 	hammer2_tid_t		mtid;
85 	hammer2_tid_t		saved_mirror_tid;
86 	time_t			save_time;
87 	hammer2_chain_save_list_t list;
88 	hammer2_dedup_t		*dedup;
89 	int			pri;
90 } hammer2_bulkfree_info_t;
91 
92 static int h2_bulkfree_test(hammer2_bulkfree_info_t *info,
93 			hammer2_blockref_t *bref, int pri);
94 
95 /*
96  * General bulk scan function with callback.  Called with a referenced
97  * but UNLOCKED parent.  The parent is returned in the same state.
98  */
99 static
100 int
101 hammer2_bulk_scan(hammer2_chain_t *parent,
102 		  int (*func)(hammer2_bulkfree_info_t *info,
103 			      hammer2_blockref_t *bref),
104 		  hammer2_bulkfree_info_t *info)
105 {
106 	hammer2_blockref_t bref;
107 	hammer2_chain_t *chain;
108 	int first = 1;
109 	int rup_error;
110 	int error;
111 
112 	++info->pri;
113 
114 	hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS |
115 				   HAMMER2_RESOLVE_SHARED);
116 	chain = NULL;
117 	rup_error = 0;
118 	error = 0;
119 
120 	/*
121 	 * Generally loop on the contents if we have not been flagged
122 	 * for abort.
123 	 *
124 	 * Remember that these chains are completely isolated from
125 	 * the frontend, so we can release locks temporarily without
126 	 * imploding.
127 	 */
128 	for (;;) {
129 		error |= hammer2_chain_scan(parent, &chain, &bref, &first,
130 					    HAMMER2_LOOKUP_NODATA |
131 					    HAMMER2_LOOKUP_SHARED);
132 
133 		/*
134 		 * Handle EOF or other error at current level.  This stops
135 		 * the bulkfree scan.
136 		 */
137 		if (error)
138 			break;
139 
140 		/*
141 		 * Account for dirents before thre data_off test, since most
142 		 * dirents do not need a data reference.
143 		 */
144 		if (bref.type == HAMMER2_BREF_TYPE_DIRENT)
145 			++info->count_dirents_scanned;
146 
147 		/*
148 		 * Ignore brefs without data (typically dirents)
149 		 */
150 		if ((bref.data_off & ~HAMMER2_OFF_MASK_RADIX) == 0)
151 			continue;
152 
153 		/*
154 		 * Process bref, chain is only non-NULL if the bref
155 		 * might be recursable (its possible that we sometimes get
156 		 * a non-NULL chain where the bref cannot be recursed).
157 		 */
158 		++info->pri;
159 		if (h2_bulkfree_test(info, &bref, 1))
160 			continue;
161 
162 		if (bref.type == HAMMER2_BREF_TYPE_INODE)
163 			++info->count_inodes_scanned;
164 
165 		error |= func(info, &bref);
166 		if (error)
167 			break;
168 
169 		/*
170 		 * A non-null chain is always returned if it is
171 		 * recursive, otherwise a non-null chain might be
172 		 * returned but usually is not when not recursive.
173 		 */
174 		if (chain == NULL)
175 			continue;
176 
177 		if (chain) {
178 			info->count_bytes_scanned += chain->bytes;
179 			++info->count_chains_scanned;
180 
181 			if (info->count_chains_scanned >=
182 			    info->count_chains_reported + 1000000 ||
183 			    (info->count_chains_scanned < 1000000 &&
184 			     info->count_chains_scanned >=
185 			     info->count_chains_reported + 100000)) {
186 				kprintf(" chains %-7ld inodes %-7ld "
187 					"dirents %-7ld bytes %5ldMB\n",
188 					info->count_chains_scanned,
189 					info->count_inodes_scanned,
190 					info->count_dirents_scanned,
191 					info->count_bytes_scanned / 1000000);
192 				info->count_chains_reported =
193 					info->count_chains_scanned;
194 			}
195 		}
196 
197 
198 		/*
199 		 * Else check type and setup depth-first scan.
200 		 *
201 		 * Account for bytes actually read.
202 		 */
203 		switch(chain->bref.type) {
204 		case HAMMER2_BREF_TYPE_INODE:
205 		case HAMMER2_BREF_TYPE_FREEMAP_NODE:
206 		case HAMMER2_BREF_TYPE_INDIRECT:
207 		case HAMMER2_BREF_TYPE_VOLUME:
208 		case HAMMER2_BREF_TYPE_FREEMAP:
209 			++info->depth;
210 			if (info->depth > 16) {
211 				hammer2_chain_save_t *save;
212 				save = kmalloc(sizeof(*save), M_HAMMER2,
213 					       M_WAITOK | M_ZERO);
214 				save->chain = chain;
215 				hammer2_chain_ref(chain);
216 				TAILQ_INSERT_TAIL(&info->list, save, entry);
217 
218 				/* guess */
219 				info->pri += 10;
220 			} else {
221 				int savepri = info->pri;
222 
223 				hammer2_chain_unlock(chain);
224 				hammer2_chain_unlock(parent);
225 				info->pri = 0;
226 				rup_error |=
227 					hammer2_bulk_scan(chain, func, info);
228 				info->pri += savepri;
229 				hammer2_chain_lock(parent,
230 						   HAMMER2_RESOLVE_ALWAYS |
231 						   HAMMER2_RESOLVE_SHARED);
232 				hammer2_chain_lock(chain,
233 						   HAMMER2_RESOLVE_ALWAYS |
234 						   HAMMER2_RESOLVE_SHARED);
235 			}
236 			--info->depth;
237 			break;
238 		case HAMMER2_BREF_TYPE_DATA:
239 			break;
240 		default:
241 			/* does not recurse */
242 			break;
243 		}
244 		if (rup_error & HAMMER2_ERROR_ABORTED)
245 			break;
246 	}
247 	if (chain) {
248 		hammer2_chain_unlock(chain);
249 		hammer2_chain_drop(chain);
250 	}
251 
252 	/*
253 	 * Save with higher pri now that we know what it is.
254 	 */
255 	h2_bulkfree_test(info, &parent->bref, info->pri + 1);
256 
257 	hammer2_chain_unlock(parent);
258 
259 	return ((error | rup_error) & ~HAMMER2_ERROR_EOF);
260 }
261 
262 /*
263  * Bulkfree algorithm
264  *
265  * Repeat {
266  *	Chain flush (partial synchronization) XXX removed
267  *	Scan the whole topology - build in-memory freemap (mark 11)
268  *	Reconcile the in-memory freemap against the on-disk freemap.
269  *		ondisk xx -> ondisk 11 (if allocated)
270  *		ondisk 11 -> ondisk 10 (if free in-memory)
271  *		ondisk 10 -> ondisk 00 (if free in-memory) - on next pass
272  * }
273  *
274  * The topology scan may have to be performed multiple times to window
275  * freemaps which are too large to fit in kernel memory.
276  *
277  * Races are handled using a double-transition (11->10, 10->00).  The bulkfree
278  * scan snapshots the volume root's blockset and thus can run concurrent with
279  * normal operations, as long as a full flush is made between each pass to
280  * synchronize any modified chains (otherwise their blocks might be improperly
281  * freed).
282  *
283  * Temporary memory in multiples of 64KB is required to reconstruct the leaf
284  * hammer2_bmap_data blocks so they can later be compared against the live
285  * freemap.  Each 64KB block represents 128 x 16KB x 1024 = ~2 GB of storage.
286  * A 32MB save area thus represents around ~1 TB.  The temporary memory
287  * allocated can be specified.  If it is not sufficient multiple topology
288  * passes will be made.
289  */
290 
291 /*
292  * Bulkfree callback info
293  */
294 static void hammer2_bulkfree_thread(void *arg __unused);
295 static void cbinfo_bmap_init(hammer2_bulkfree_info_t *cbinfo, size_t size);
296 static int h2_bulkfree_callback(hammer2_bulkfree_info_t *cbinfo,
297 			hammer2_blockref_t *bref);
298 static int h2_bulkfree_sync(hammer2_bulkfree_info_t *cbinfo);
299 static void h2_bulkfree_sync_adjust(hammer2_bulkfree_info_t *cbinfo,
300 			hammer2_off_t data_off, hammer2_bmap_data_t *live,
301 			hammer2_bmap_data_t *bmap, hammer2_key_t alloc_base);
302 
303 void
304 hammer2_bulkfree_init(hammer2_dev_t *hmp)
305 {
306 	hammer2_thr_create(&hmp->bfthr, NULL, hmp,
307 			   hmp->devrepname, -1, -1,
308 			   hammer2_bulkfree_thread);
309 }
310 
311 void
312 hammer2_bulkfree_uninit(hammer2_dev_t *hmp)
313 {
314 	hammer2_thr_delete(&hmp->bfthr);
315 }
316 
317 static void
318 hammer2_bulkfree_thread(void *arg)
319 {
320 	hammer2_thread_t *thr = arg;
321 	hammer2_ioc_bulkfree_t bfi;
322 	uint32_t flags;
323 
324 	for (;;) {
325 		hammer2_thr_wait_any(thr,
326 				     HAMMER2_THREAD_STOP |
327 				     HAMMER2_THREAD_FREEZE |
328 				     HAMMER2_THREAD_UNFREEZE |
329 				     HAMMER2_THREAD_REMASTER,
330 				     hz * 60);
331 
332 		flags = thr->flags;
333 		cpu_ccfence();
334 		if (flags & HAMMER2_THREAD_STOP)
335 			break;
336 		if (flags & HAMMER2_THREAD_FREEZE) {
337 			hammer2_thr_signal2(thr, HAMMER2_THREAD_FROZEN,
338 						 HAMMER2_THREAD_FREEZE);
339 			continue;
340 		}
341 		if (flags & HAMMER2_THREAD_UNFREEZE) {
342 			hammer2_thr_signal2(thr, 0,
343 						 HAMMER2_THREAD_FROZEN |
344 						 HAMMER2_THREAD_UNFREEZE);
345 			continue;
346 		}
347 		if (flags & HAMMER2_THREAD_FROZEN)
348 			continue;
349 		if (flags & HAMMER2_THREAD_REMASTER) {
350 			hammer2_thr_signal2(thr, 0, HAMMER2_THREAD_REMASTER);
351 			bzero(&bfi, sizeof(bfi));
352 			bfi.size = 8192 * 1024;
353 			/* hammer2_bulkfree_pass(thr->hmp, &bfi); */
354 		}
355 	}
356 	thr->td = NULL;
357 	hammer2_thr_signal(thr, HAMMER2_THREAD_STOPPED);
358 	/* structure can go invalid at this point */
359 }
360 
361 int
362 hammer2_bulkfree_pass(hammer2_dev_t *hmp, hammer2_chain_t *vchain,
363 		      hammer2_ioc_bulkfree_t *bfi)
364 {
365 	hammer2_bulkfree_info_t cbinfo;
366 	hammer2_chain_save_t *save;
367 	hammer2_off_t incr;
368 	size_t size;
369 	int error;
370 
371 	/*
372 	 * We have to clear the live dedup cache as it might have entries
373 	 * that are freeable as of now.  Any new entries in the dedup cache
374 	 * made after this point, even if they become freeable, will have
375 	 * previously been fully allocated and will be protected by the
376 	 * 2-stage bulkfree.
377 	 */
378 	hammer2_dedup_clear(hmp);
379 
380 	/*
381 	 * Setup for free pass using the buffer size specified by the
382 	 * hammer2 utility, 32K-aligned.
383 	 */
384 	bzero(&cbinfo, sizeof(cbinfo));
385 	size = (bfi->size + HAMMER2_FREEMAP_LEVELN_PSIZE - 1) &
386 	       ~(size_t)(HAMMER2_FREEMAP_LEVELN_PSIZE - 1);
387 
388 	/*
389 	 * Cap at 1/4 physical memory (hammer2 utility will not normally
390 	 * ever specify a buffer this big, but leave the option available).
391 	 */
392 	if (size > kmem_lim_size() * 1024 * 1024 / 4) {
393 		size = kmem_lim_size() * 1024 * 1024 / 4;
394 		kprintf("hammer2: Warning: capping bulkfree buffer at %jdM\n",
395 			(intmax_t)size / (1024 * 1024));
396 	}
397 
398 #define HAMMER2_FREEMAP_SIZEDIV	\
399 	(HAMMER2_FREEMAP_LEVEL1_SIZE / HAMMER2_FREEMAP_LEVELN_PSIZE)
400 #define HAMMER2_FREEMAP_SIZEMASK	(HAMMER2_FREEMAP_SIZEDIV - 1)
401 
402 	/*
403 	 * Cap at the size needed to cover the whole volume to avoid
404 	 * making an unnecessarily large allocation.
405 	 */
406 	if (size > hmp->voldata.volu_size / HAMMER2_FREEMAP_SIZEDIV) {
407 		size = (hmp->voldata.volu_size + HAMMER2_FREEMAP_SIZEMASK) /
408 			HAMMER2_FREEMAP_SIZEDIV;
409 	}
410 
411 	/*
412 	 * Minimum bitmap buffer size, then align to a LEVELN_PSIZE (32K)
413 	 * boundary.
414 	 */
415 	if (size < 1024 * 1024)
416 		size = 1024 * 1024;
417 	size = (size + HAMMER2_FREEMAP_LEVELN_PSIZE - 1) &
418 	       ~(size_t)(HAMMER2_FREEMAP_LEVELN_PSIZE - 1);
419 
420 	cbinfo.hmp = hmp;
421 	cbinfo.bmap = kmem_alloc_swapbacked(&cbinfo.kp, size, VM_SUBSYS_HAMMER);
422 	cbinfo.saved_mirror_tid = hmp->voldata.mirror_tid;
423 
424 	cbinfo.dedup = kmalloc(sizeof(*cbinfo.dedup) * HAMMER2_DEDUP_HEUR_SIZE,
425 			       M_HAMMER2, M_WAITOK | M_ZERO);
426 
427 	kprintf("hammer2: bulkfree buf=%jdM\n",
428 		(intmax_t)size / (1024 * 1024));
429 
430 	/*
431 	 * Normalize start point to a 2GB boundary.  We operate on a
432 	 * 64KB leaf bitmap boundary which represents 2GB of storage.
433 	 */
434 	cbinfo.sbase = bfi->sbase;
435 	if (cbinfo.sbase > hmp->voldata.volu_size)
436 		cbinfo.sbase = hmp->voldata.volu_size;
437 	cbinfo.sbase &= ~HAMMER2_FREEMAP_LEVEL1_MASK;
438 	TAILQ_INIT(&cbinfo.list);
439 
440 	cbinfo.bulkfree_ticks = ticks;
441 
442 	/*
443 	 * Loop on a full meta-data scan as many times as required to
444 	 * get through all available storage.
445 	 */
446 	error = 0;
447 	while (cbinfo.sbase < hmp->voldata.volu_size) {
448 		/*
449 		 * We have enough ram to represent (incr) bytes of storage.
450 		 * Each 64KB of ram represents 2GB of storage.
451 		 *
452 		 * We must also clean out our de-duplication heuristic for
453 		 * each (incr) bytes of storage, otherwise we wind up not
454 		 * scanning meta-data for later areas of storage because
455 		 * they had already been scanned in earlier areas of storage.
456 		 * Since the ranging is different, we have to restart
457 		 * the dedup heuristic too.
458 		 */
459 		int allmedia;
460 
461 		cbinfo_bmap_init(&cbinfo, size);
462 		bzero(cbinfo.dedup, sizeof(*cbinfo.dedup) *
463 				    HAMMER2_DEDUP_HEUR_SIZE);
464 		cbinfo.count_inodes_scanned = 0;
465 		cbinfo.count_dirents_scanned = 0;
466 		cbinfo.count_bytes_scanned = 0;
467 		cbinfo.count_chains_scanned = 0;
468 		cbinfo.count_chains_reported = 0;
469 
470 		incr = size / HAMMER2_FREEMAP_LEVELN_PSIZE *
471 		       HAMMER2_FREEMAP_LEVEL1_SIZE;
472 		if (hmp->voldata.volu_size - cbinfo.sbase <= incr) {
473 			cbinfo.sstop = hmp->voldata.volu_size;
474 			allmedia = 1;
475 		} else {
476 			cbinfo.sstop = cbinfo.sbase + incr;
477 			allmedia = 0;
478 		}
479 		kprintf("hammer2: pass %016jx-%016jx ",
480 			(intmax_t)cbinfo.sbase,
481 			(intmax_t)cbinfo.sstop);
482 		if (allmedia && cbinfo.sbase == 0)
483 			kprintf("(all media)\n");
484 		else if (allmedia)
485 			kprintf("(remaining media)\n");
486 		else
487 			kprintf("(%jdGB of media)\n",
488 				(intmax_t)incr / (1024L*1024*1024));
489 
490 		/*
491 		 * Scan topology for stuff inside this range.
492 		 *
493 		 * NOTE - By not using a transaction the operation can
494 		 *	  run concurrent with the frontend as well as
495 		 *	  with flushes.
496 		 *
497 		 *	  We cannot safely set a mtid without a transaction,
498 		 *	  and in fact we don't want to set one anyway.  We
499 		 *	  want the bulkfree to be passive and no interfere
500 		 *	  with crash recovery.
501 		 */
502 #undef HAMMER2_BULKFREE_TRANS	/* undef - don't use transaction */
503 #ifdef HAMMER2_BULKFREE_TRANS
504 		hammer2_trans_init(hmp->spmp, 0);
505 		cbinfo.mtid = hammer2_trans_sub(hmp->spmp);
506 #else
507 		cbinfo.mtid = 0;
508 #endif
509 		cbinfo.pri = 0;
510 		error |= hammer2_bulk_scan(vchain, h2_bulkfree_callback,
511 					   &cbinfo);
512 
513 		while ((save = TAILQ_FIRST(&cbinfo.list)) != NULL &&
514 		       error == 0) {
515 			TAILQ_REMOVE(&cbinfo.list, save, entry);
516 			cbinfo.pri = 0;
517 			error |= hammer2_bulk_scan(save->chain,
518 						   h2_bulkfree_callback,
519 						   &cbinfo);
520 			hammer2_chain_drop(save->chain);
521 			kfree(save, M_HAMMER2);
522 		}
523 		while (save) {
524 			TAILQ_REMOVE(&cbinfo.list, save, entry);
525 			hammer2_chain_drop(save->chain);
526 			kfree(save, M_HAMMER2);
527 			save = TAILQ_FIRST(&cbinfo.list);
528 		}
529 
530 		/*
531 		 * If the complete scan succeeded we can synchronize our
532 		 * in-memory freemap against live storage.  If an abort
533 		 * occured we cannot safely synchronize our partially
534 		 * filled-out in-memory freemap.
535 		 */
536 		if (error) {
537 			kprintf("bulkfree lastdrop %d %d error=0x%04x\n",
538 				vchain->refs, vchain->core.chain_count, error);
539 		} else {
540 			kprintf("bulkfree lastdrop %d %d\n",
541 				vchain->refs, vchain->core.chain_count);
542 
543 			error = h2_bulkfree_sync(&cbinfo);
544 
545 			hammer2_voldata_lock(hmp);
546 			hammer2_voldata_modify(hmp);
547 			hmp->voldata.allocator_free += cbinfo.adj_free;
548 			hammer2_voldata_unlock(hmp);
549 		}
550 
551 		/*
552 		 * Cleanup for next loop.
553 		 */
554 #ifdef HAMMER2_BULKFREE_TRANS
555 		hammer2_trans_done(hmp->spmp, 0);
556 #endif
557 		if (error)
558 			break;
559 		cbinfo.sbase = cbinfo.sstop;
560 		cbinfo.adj_free = 0;
561 	}
562 	kmem_free_swapbacked(&cbinfo.kp);
563 	kfree(cbinfo.dedup, M_HAMMER2);
564 	cbinfo.dedup = NULL;
565 
566 	bfi->sstop = cbinfo.sbase;
567 
568 	incr = bfi->sstop / (hmp->voldata.volu_size / 10000);
569 	if (incr > 10000)
570 		incr = 10000;
571 
572 	kprintf("bulkfree pass statistics (%d.%02d%% storage processed):\n",
573 		(int)incr / 100,
574 		(int)incr % 100);
575 
576 	if (error) {
577 		kprintf("    bulkfree was aborted\n");
578 	} else {
579 		kprintf("    transition->free   %ld\n", cbinfo.count_10_00);
580 		kprintf("    transition->staged %ld\n", cbinfo.count_11_10);
581 		kprintf("    ERR(00)->allocated %ld\n", cbinfo.count_00_11);
582 		kprintf("    ERR(01)->allocated %ld\n", cbinfo.count_01_11);
583 		kprintf("    staged->allocated  %ld\n", cbinfo.count_10_11);
584 		kprintf("    ~2MB segs cleaned  %ld\n", cbinfo.count_l0cleans);
585 		kprintf("    linear adjusts     %ld\n",
586 			cbinfo.count_linadjusts);
587 		kprintf("    dedup factor       %ld\n",
588 			cbinfo.count_dedup_factor);
589 	}
590 
591 	return error;
592 }
593 
594 static void
595 cbinfo_bmap_init(hammer2_bulkfree_info_t *cbinfo, size_t size)
596 {
597 	hammer2_bmap_data_t *bmap = cbinfo->bmap;
598 	hammer2_key_t key = cbinfo->sbase;
599 	hammer2_key_t lokey;
600 	hammer2_key_t hikey;
601 
602 	lokey = (cbinfo->hmp->voldata.allocator_beg + HAMMER2_SEGMASK64) &
603 		~HAMMER2_SEGMASK64;
604 	hikey = cbinfo->hmp->voldata.volu_size & ~HAMMER2_SEGMASK64;
605 
606 	bzero(bmap, size);
607 	while (size) {
608 		bzero(bmap, sizeof(*bmap));
609 		if (lokey < H2FMBASE(key, HAMMER2_FREEMAP_LEVEL1_RADIX))
610 			lokey = H2FMBASE(key, HAMMER2_FREEMAP_LEVEL1_RADIX);
611 		if (lokey < H2FMZONEBASE(key) + HAMMER2_ZONE_SEG64)
612 			lokey = H2FMZONEBASE(key) + HAMMER2_ZONE_SEG64;
613 		if (key < lokey || key >= hikey) {
614 			memset(bmap->bitmapq, -1,
615 			       sizeof(bmap->bitmapq));
616 			bmap->avail = 0;
617 			bmap->linear = HAMMER2_SEGSIZE;
618 		} else {
619 			bmap->avail = HAMMER2_FREEMAP_LEVEL0_SIZE;
620 		}
621 		size -= sizeof(*bmap);
622 		key += HAMMER2_FREEMAP_LEVEL0_SIZE;
623 		++bmap;
624 	}
625 }
626 
627 static int
628 h2_bulkfree_callback(hammer2_bulkfree_info_t *cbinfo, hammer2_blockref_t *bref)
629 {
630 	hammer2_bmap_data_t *bmap;
631 	hammer2_off_t data_off;
632 	uint16_t class;
633 	size_t bytes;
634 	int radix;
635 
636 	/*
637 	 * Check for signal and allow yield to userland during scan.
638 	 */
639 	if (hammer2_signal_check(&cbinfo->save_time))
640 		return HAMMER2_ERROR_ABORTED;
641 
642 	/*
643 	 * Deal with kernel thread cpu or I/O hogging by limiting the
644 	 * number of chains scanned per second to hammer2_bulkfree_tps.
645 	 * Ignore leaf records (DIRENT and DATA), no per-record I/O is
646 	 * involved for those since we don't load their data.
647 	 */
648 	if (bref->type != HAMMER2_BREF_TYPE_DATA &&
649 	    bref->type != HAMMER2_BREF_TYPE_DIRENT) {
650 		++cbinfo->bulkfree_calls;
651 		if (cbinfo->bulkfree_calls > hammer2_bulkfree_tps) {
652 			int dticks = ticks - cbinfo->bulkfree_ticks;
653 			if (dticks < 0)
654 				dticks = 0;
655 			if (dticks < hz) {
656 				tsleep(&cbinfo->bulkfree_ticks, 0,
657 				       "h2bw", hz - dticks);
658 			}
659 			cbinfo->bulkfree_calls = 0;
660 			cbinfo->bulkfree_ticks = ticks;
661 		}
662 	}
663 
664 	/*
665 	 * Calculate the data offset and determine if it is within
666 	 * the current freemap range being gathered.
667 	 */
668 	data_off = bref->data_off & ~HAMMER2_OFF_MASK_RADIX;
669 	if (data_off < cbinfo->sbase || data_off >= cbinfo->sstop)
670 		return 0;
671 	if (data_off < cbinfo->hmp->voldata.allocator_beg)
672 		return 0;
673 	if (data_off >= cbinfo->hmp->voldata.volu_size)
674 		return 0;
675 
676 	/*
677 	 * Calculate the information needed to generate the in-memory
678 	 * freemap record.
679 	 *
680 	 * Hammer2 does not allow allocations to cross the L1 (2GB) boundary,
681 	 * it's a problem if it does.  (Or L0 (2MB) for that matter).
682 	 */
683 	radix = (int)(bref->data_off & HAMMER2_OFF_MASK_RADIX);
684 	KKASSERT(radix != 0);
685 	bytes = (size_t)1 << radix;
686 	class = (bref->type << 8) | hammer2_devblkradix(radix);
687 
688 	if (data_off + bytes > cbinfo->sstop) {
689 		kprintf("hammer2_bulkfree_scan: illegal 2GB boundary "
690 			"%016jx %016jx/%d\n",
691 			(intmax_t)bref->data_off,
692 			(intmax_t)bref->key,
693 			bref->keybits);
694 		bytes = cbinfo->sstop - data_off;	/* XXX */
695 	}
696 
697 	/*
698 	 * Convert to a storage offset relative to the beginning of the
699 	 * storage range we are collecting.  Then lookup the level0 bmap entry.
700 	 */
701 	data_off -= cbinfo->sbase;
702 	bmap = cbinfo->bmap + (data_off >> HAMMER2_FREEMAP_LEVEL0_RADIX);
703 
704 	/*
705 	 * Convert data_off to a bmap-relative value (~4MB storage range).
706 	 * Adjust linear, class, and avail.
707 	 *
708 	 * Hammer2 does not allow allocations to cross the L0 (4MB) boundary,
709 	 */
710 	data_off &= HAMMER2_FREEMAP_LEVEL0_MASK;
711 	if (data_off + bytes > HAMMER2_FREEMAP_LEVEL0_SIZE) {
712 		kprintf("hammer2_bulkfree_scan: illegal 4MB boundary "
713 			"%016jx %016jx/%d\n",
714 			(intmax_t)bref->data_off,
715 			(intmax_t)bref->key,
716 			bref->keybits);
717 		bytes = HAMMER2_FREEMAP_LEVEL0_SIZE - data_off;
718 	}
719 
720 	if (bmap->class == 0) {
721 		bmap->class = class;
722 		bmap->avail = HAMMER2_FREEMAP_LEVEL0_SIZE;
723 	}
724 
725 	/*
726 	 * NOTE: bmap->class does not have to match class.  Classification
727 	 *	 is relaxed when free space is low, so some mixing can occur.
728 	 */
729 #if 0
730 	/*
731 	 * XXX removed
732 	 */
733 	if (bmap->class != class) {
734 		kprintf("hammer2_bulkfree_scan: illegal mixed class "
735 			"%016jx %016jx/%d (%04x vs %04x)\n",
736 			(intmax_t)bref->data_off,
737 			(intmax_t)bref->key,
738 			bref->keybits,
739 			class, bmap->class);
740 	}
741 #endif
742 
743 	/*
744 	 * Just record the highest byte-granular offset for now.  Do not
745 	 * match against allocations which are in multiples of whole blocks.
746 	 *
747 	 * Make sure that any in-block linear offset at least covers the
748 	 * data range.  This can cause bmap->linear to become block-aligned.
749 	 */
750 	if (bytes & HAMMER2_FREEMAP_BLOCK_MASK) {
751 		if (bmap->linear < (int32_t)data_off + (int32_t)bytes)
752 			bmap->linear = (int32_t)data_off + (int32_t)bytes;
753 	} else if (bmap->linear >= (int32_t)data_off &&
754 		   bmap->linear < (int32_t)data_off + (int32_t)bytes) {
755 		bmap->linear = (int32_t)data_off + (int32_t)bytes;
756 	}
757 
758 	/*
759 	 * Adjust the hammer2_bitmap_t bitmap[HAMMER2_BMAP_ELEMENTS].
760 	 * 64-bit entries, 2 bits per entry, to code 11.
761 	 *
762 	 * NOTE: data_off mask to 524288, shift right by 14 (radix for 16384),
763 	 *	 and multiply shift amount by 2 for sets of 2 bits.
764 	 *
765 	 * NOTE: The allocation can be smaller than HAMMER2_FREEMAP_BLOCK_SIZE.
766 	 *	 also, data_off may not be FREEMAP_BLOCK_SIZE aligned.
767 	 */
768 	while (bytes > 0) {
769 		hammer2_bitmap_t bmask;
770 		int bindex;
771 
772 		bindex = (int)data_off >> (HAMMER2_FREEMAP_BLOCK_RADIX +
773 					   HAMMER2_BMAP_INDEX_RADIX);
774 		bmask = (hammer2_bitmap_t)3 <<
775 			((((int)data_off & HAMMER2_BMAP_INDEX_MASK) >>
776 			 HAMMER2_FREEMAP_BLOCK_RADIX) << 1);
777 
778 		/*
779 		 * NOTE! The (avail) calculation is bitmap-granular.  Multiple
780 		 *	 sub-granular records can wind up at the same bitmap
781 		 *	 position.
782 		 */
783 		if ((bmap->bitmapq[bindex] & bmask) == 0) {
784 			if (bytes < HAMMER2_FREEMAP_BLOCK_SIZE) {
785 				bmap->avail -= HAMMER2_FREEMAP_BLOCK_SIZE;
786 			} else {
787 				bmap->avail -= bytes;
788 			}
789 			bmap->bitmapq[bindex] |= bmask;
790 		}
791 		data_off += HAMMER2_FREEMAP_BLOCK_SIZE;
792 		if (bytes < HAMMER2_FREEMAP_BLOCK_SIZE)
793 			bytes = 0;
794 		else
795 			bytes -= HAMMER2_FREEMAP_BLOCK_SIZE;
796 	}
797 	return 0;
798 }
799 
800 /*
801  * Synchronize the in-memory bitmap with the live freemap.  This is not a
802  * direct copy.  Instead the bitmaps must be compared:
803  *
804  *	In-memory	Live-freemap
805  *	   00		  11 -> 10	(do nothing if live modified)
806  *			  10 -> 00	(do nothing if live modified)
807  *	   11		  10 -> 11	handles race against live
808  *			  ** -> 11	nominally warn of corruption
809  *
810  * We must also fixup the hints in HAMMER2_BREF_TYPE_FREEMAP_LEAF.
811  */
812 static int
813 h2_bulkfree_sync(hammer2_bulkfree_info_t *cbinfo)
814 {
815 	hammer2_off_t data_off;
816 	hammer2_key_t key;
817 	hammer2_key_t key_dummy;
818 	hammer2_bmap_data_t *bmap;
819 	hammer2_bmap_data_t *live;
820 	hammer2_chain_t *live_parent;
821 	hammer2_chain_t *live_chain;
822 	int bmapindex;
823 	int error;
824 
825 	kprintf("hammer2_bulkfree - range ");
826 
827 	if (cbinfo->sbase < cbinfo->hmp->voldata.allocator_beg)
828 		kprintf("%016jx-",
829 			(intmax_t)cbinfo->hmp->voldata.allocator_beg);
830 	else
831 		kprintf("%016jx-",
832 			(intmax_t)cbinfo->sbase);
833 
834 	if (cbinfo->sstop > cbinfo->hmp->voldata.volu_size)
835 		kprintf("%016jx\n",
836 			(intmax_t)cbinfo->hmp->voldata.volu_size);
837 	else
838 		kprintf("%016jx\n",
839 			(intmax_t)cbinfo->sstop);
840 
841 	data_off = cbinfo->sbase;
842 	bmap = cbinfo->bmap;
843 
844 	live_parent = &cbinfo->hmp->fchain;
845 	hammer2_chain_ref(live_parent);
846 	hammer2_chain_lock(live_parent, HAMMER2_RESOLVE_ALWAYS);
847 	live_chain = NULL;
848 	error = 0;
849 
850 	/*
851 	 * Iterate each hammer2_bmap_data_t line (128 bytes) managing
852 	 * 4MB of storage.
853 	 */
854 	while (data_off < cbinfo->sstop) {
855 		/*
856 		 * The freemap is not used below allocator_beg or beyond
857 		 * volu_size.
858 		 */
859 
860 		if (data_off < cbinfo->hmp->voldata.allocator_beg)
861 			goto next;
862 		if (data_off >= cbinfo->hmp->voldata.volu_size)
863 			goto next;
864 
865 		/*
866 		 * Locate the freemap leaf on the live filesystem
867 		 */
868 		key = (data_off & ~HAMMER2_FREEMAP_LEVEL1_MASK);
869 
870 		if (live_chain == NULL || live_chain->bref.key != key) {
871 			if (live_chain) {
872 				hammer2_chain_unlock(live_chain);
873 				hammer2_chain_drop(live_chain);
874 			}
875 			live_chain = hammer2_chain_lookup(
876 					    &live_parent,
877 					    &key_dummy,
878 					    key,
879 					    key + HAMMER2_FREEMAP_LEVEL1_MASK,
880 					    &error,
881 					    HAMMER2_LOOKUP_ALWAYS);
882 			if (error) {
883 				kprintf("hammer2_bulkfree: freemap lookup "
884 					"error near %016jx, error %s\n",
885 					(intmax_t)data_off,
886 					hammer2_error_str(live_chain->error));
887 				break;
888 			}
889 		}
890 		if (live_chain == NULL) {
891 			/*
892 			 * XXX if we implement a full recovery mode we need
893 			 * to create/recreate missing freemap chains if our
894 			 * bmap has any allocated blocks.
895 			 */
896 			if (bmap->class &&
897 			    bmap->avail != HAMMER2_FREEMAP_LEVEL0_SIZE) {
898 				kprintf("hammer2_bulkfree: cannot locate "
899 					"live leaf for allocated data "
900 					"near %016jx\n",
901 					(intmax_t)data_off);
902 			}
903 			goto next;
904 		}
905 		if (live_chain->error) {
906 			kprintf("hammer2_bulkfree: unable to access freemap "
907 				"near %016jx, error %s\n",
908 				(intmax_t)data_off,
909 				hammer2_error_str(live_chain->error));
910 			hammer2_chain_unlock(live_chain);
911 			hammer2_chain_drop(live_chain);
912 			live_chain = NULL;
913 			goto next;
914 		}
915 
916 		bmapindex = (data_off & HAMMER2_FREEMAP_LEVEL1_MASK) >>
917 			    HAMMER2_FREEMAP_LEVEL0_RADIX;
918 		live = &live_chain->data->bmdata[bmapindex];
919 
920 		/*
921 		 * Shortcut if the bitmaps match and the live linear
922 		 * indicator is sane.  We can't do a perfect check of
923 		 * live->linear because the only real requirement is that
924 		 * if it is not block-aligned, that it not cover the space
925 		 * within its current block which overlaps one of the data
926 		 * ranges we scan.  We don't retain enough fine-grained
927 		 * data in our scan to be able to set it exactly.
928 		 *
929 		 * TODO - we could shortcut this by testing that both
930 		 * live->class and bmap->class are 0, and both avails are
931 		 * set to HAMMER2_FREEMAP_LEVEL0_SIZE (4MB).
932 		 */
933 		if (bcmp(live->bitmapq, bmap->bitmapq,
934 			 sizeof(bmap->bitmapq)) == 0 &&
935 		    live->linear >= bmap->linear) {
936 			goto next;
937 		}
938 		if (hammer2_debug & 1) {
939 			kprintf("live %016jx %04d.%04x (avail=%d)\n",
940 				data_off, bmapindex, live->class, live->avail);
941 		}
942 
943 		hammer2_chain_modify(live_chain, cbinfo->mtid, 0, 0);
944 		live_chain->bref.check.freemap.bigmask = -1;
945 		cbinfo->hmp->freemap_relaxed = 0;	/* reset heuristic */
946 		live = &live_chain->data->bmdata[bmapindex];
947 
948 		h2_bulkfree_sync_adjust(cbinfo, data_off, live, bmap,
949 					live_chain->bref.key +
950 					bmapindex *
951 					HAMMER2_FREEMAP_LEVEL0_SIZE);
952 next:
953 		data_off += HAMMER2_FREEMAP_LEVEL0_SIZE;
954 		++bmap;
955 	}
956 	if (live_chain) {
957 		hammer2_chain_unlock(live_chain);
958 		hammer2_chain_drop(live_chain);
959 	}
960 	if (live_parent) {
961 		hammer2_chain_unlock(live_parent);
962 		hammer2_chain_drop(live_parent);
963 	}
964 	return error;
965 }
966 
967 /*
968  * Merge the bulkfree bitmap against the existing bitmap.
969  */
970 static
971 void
972 h2_bulkfree_sync_adjust(hammer2_bulkfree_info_t *cbinfo,
973 			hammer2_off_t data_off, hammer2_bmap_data_t *live,
974 			hammer2_bmap_data_t *bmap, hammer2_key_t alloc_base)
975 {
976 	int bindex;
977 	int scount;
978 	hammer2_off_t tmp_off;
979 	hammer2_bitmap_t lmask;
980 	hammer2_bitmap_t mmask;
981 
982 	tmp_off = data_off;
983 
984 	for (bindex = 0; bindex < HAMMER2_BMAP_ELEMENTS; ++bindex) {
985 		lmask = live->bitmapq[bindex];	/* live */
986 		mmask = bmap->bitmapq[bindex];	/* snapshotted bulkfree */
987 		if (lmask == mmask) {
988 			tmp_off += HAMMER2_BMAP_INDEX_SIZE;
989 			continue;
990 		}
991 
992 		for (scount = 0;
993 		     scount < HAMMER2_BMAP_BITS_PER_ELEMENT;
994 		     scount += 2) {
995 			if ((mmask & 3) == 0) {
996 				/*
997 				 * in-memory 00		live 11 -> 10
998 				 *			live 10 -> 00
999 				 *
1000 				 * Storage might be marked allocated or
1001 				 * staged and must be remarked staged or
1002 				 * free.
1003 				 */
1004 				switch (lmask & 3) {
1005 				case 0:	/* 00 */
1006 					break;
1007 				case 1:	/* 01 */
1008 					kprintf("hammer2_bulkfree: cannot "
1009 						"transition m=00/l=01\n");
1010 					break;
1011 				case 2:	/* 10 -> 00 */
1012 					live->bitmapq[bindex] &=
1013 					    ~((hammer2_bitmap_t)2 << scount);
1014 					live->avail +=
1015 						HAMMER2_FREEMAP_BLOCK_SIZE;
1016 					if (live->avail >
1017 					    HAMMER2_FREEMAP_LEVEL0_SIZE) {
1018 						live->avail =
1019 						    HAMMER2_FREEMAP_LEVEL0_SIZE;
1020 					}
1021 					cbinfo->adj_free +=
1022 						HAMMER2_FREEMAP_BLOCK_SIZE;
1023 					++cbinfo->count_10_00;
1024 					hammer2_io_dedup_assert(
1025 						cbinfo->hmp,
1026 						tmp_off |
1027 						HAMMER2_FREEMAP_BLOCK_RADIX,
1028 						HAMMER2_FREEMAP_BLOCK_SIZE);
1029 					break;
1030 				case 3:	/* 11 -> 10 */
1031 					live->bitmapq[bindex] &=
1032 					    ~((hammer2_bitmap_t)1 << scount);
1033 					++cbinfo->count_11_10;
1034 					hammer2_io_dedup_delete(
1035 						cbinfo->hmp,
1036 						HAMMER2_BREF_TYPE_DATA,
1037 						tmp_off |
1038 						HAMMER2_FREEMAP_BLOCK_RADIX,
1039 						HAMMER2_FREEMAP_BLOCK_SIZE);
1040 					break;
1041 				}
1042 			} else if ((mmask & 3) == 3) {
1043 				/*
1044 				 * in-memory 11		live 10 -> 11
1045 				 *			live ** -> 11
1046 				 *
1047 				 * Storage might be incorrectly marked free
1048 				 * or staged and must be remarked fully
1049 				 * allocated.
1050 				 */
1051 				switch (lmask & 3) {
1052 				case 0:	/* 00 */
1053 					++cbinfo->count_00_11;
1054 					cbinfo->adj_free -=
1055 						HAMMER2_FREEMAP_BLOCK_SIZE;
1056 					live->avail -=
1057 						HAMMER2_FREEMAP_BLOCK_SIZE;
1058 					if ((int32_t)live->avail < 0)
1059 						live->avail = 0;
1060 					break;
1061 				case 1:	/* 01 */
1062 					++cbinfo->count_01_11;
1063 					break;
1064 				case 2:	/* 10 -> 11 */
1065 					++cbinfo->count_10_11;
1066 					break;
1067 				case 3:	/* 11 */
1068 					break;
1069 				}
1070 				live->bitmapq[bindex] |=
1071 					((hammer2_bitmap_t)3 << scount);
1072 			}
1073 			mmask >>= 2;
1074 			lmask >>= 2;
1075 			tmp_off += HAMMER2_FREEMAP_BLOCK_SIZE;
1076 		}
1077 	}
1078 
1079 	/*
1080 	 * Determine if the live bitmap is completely free and reset its
1081 	 * fields if so.  Otherwise check to see if we can reduce the linear
1082 	 * offset.
1083 	 */
1084 	for (bindex = HAMMER2_BMAP_ELEMENTS - 1; bindex >= 0; --bindex) {
1085 		if (live->bitmapq[bindex] != 0)
1086 			break;
1087 	}
1088 	if (bindex < 0) {
1089 		/*
1090 		 * Completely empty, reset entire segment
1091 		 */
1092 #if 0
1093 		kprintf("hammer2: cleanseg %016jx.%04x (%d)\n",
1094 			alloc_base, live->class, live->avail);
1095 #endif
1096 		live->avail = HAMMER2_FREEMAP_LEVEL0_SIZE;
1097 		live->class = 0;
1098 		live->linear = 0;
1099 		++cbinfo->count_l0cleans;
1100 	} else if (bindex < 7) {
1101 		/*
1102 		 * Partially full, bitmapq[bindex] != 0.  Our bulkfree pass
1103 		 * does not record enough information to set live->linear
1104 		 * exactly.
1105 		 *
1106 		 * NOTE: Setting live->linear to a sub-block (16K) boundary
1107 		 *	 forces the live code to iterate to the next fully
1108 		 *	 free block.  It does NOT mean that all blocks above
1109 		 *	 live->linear are available.
1110 		 *
1111 		 *	 Setting live->linear to a fragmentary (less than
1112 		 *	 16K) boundary allows allocations to iterate within
1113 		 *	 that sub-block.
1114 		 */
1115 		if (live->linear < bmap->linear &&
1116 		    ((live->linear ^ bmap->linear) &
1117 		     ~HAMMER2_FREEMAP_BLOCK_MASK) == 0) {
1118 			/*
1119 			 * If greater than but still within the same
1120 			 * sub-block as live we can adjust linear upward.
1121 			 */
1122 			live->linear = bmap->linear;
1123 			++cbinfo->count_linadjusts;
1124 		} else {
1125 			/*
1126 			 * Otherwise adjust to the nearest higher or same
1127 			 * sub-block boundary.  The live system may have
1128 			 * bounced live->linear around so we cannot make any
1129 			 * assumptions with regards to available fragmentary
1130 			 * allocations.
1131 			 */
1132 			live->linear =
1133 				(bmap->linear + HAMMER2_FREEMAP_BLOCK_MASK) &
1134 				~HAMMER2_FREEMAP_BLOCK_MASK;
1135 			++cbinfo->count_linadjusts;
1136 		}
1137 	} else {
1138 		/*
1139 		 * Completely full, effectively disable the linear iterator
1140 		 */
1141 		live->linear = HAMMER2_SEGSIZE;
1142 	}
1143 
1144 #if 0
1145 	if (bmap->class) {
1146 		kprintf("%016jx %04d.%04x (avail=%7d) "
1147 			"%08x %08x %08x %08x %08x %08x %08x %08x\n",
1148 			(intmax_t)data_off,
1149 			(int)((data_off &
1150 			       HAMMER2_FREEMAP_LEVEL1_MASK) >>
1151 			      HAMMER2_FREEMAP_LEVEL0_RADIX),
1152 			bmap->class,
1153 			bmap->avail,
1154 			bmap->bitmap[0], bmap->bitmap[1],
1155 			bmap->bitmap[2], bmap->bitmap[3],
1156 			bmap->bitmap[4], bmap->bitmap[5],
1157 			bmap->bitmap[6], bmap->bitmap[7]);
1158 	}
1159 #endif
1160 }
1161 
1162 /*
1163  * BULKFREE DEDUP HEURISTIC
1164  *
1165  * WARNING! This code is SMP safe but the heuristic allows SMP collisions.
1166  *	    All fields must be loaded into locals and validated.
1167  */
1168 static
1169 int
1170 h2_bulkfree_test(hammer2_bulkfree_info_t *cbinfo, hammer2_blockref_t *bref,
1171 		 int pri)
1172 {
1173 	hammer2_dedup_t *dedup;
1174 	int best;
1175 	int n;
1176 	int i;
1177 
1178 	n = hammer2_icrc32(&bref->data_off, sizeof(bref->data_off));
1179 	dedup = cbinfo->dedup + (n & (HAMMER2_DEDUP_HEUR_MASK & ~7));
1180 
1181 	for (i = best = 0; i < 8; ++i) {
1182 		if (dedup[i].data_off == bref->data_off) {
1183 			if (dedup[i].ticks < pri)
1184 				dedup[i].ticks = pri;
1185 			if (pri == 1)
1186 				cbinfo->count_dedup_factor += dedup[i].ticks;
1187 			return 1;
1188 		}
1189 		if (dedup[i].ticks < dedup[best].ticks)
1190 			best = i;
1191 	}
1192 	dedup[best].data_off = bref->data_off;
1193 	dedup[best].ticks = pri;
1194 
1195 	return 0;
1196 }
1197