1 /*
2  * Copyright (c) 2011-2015 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  * by Venkatesh Srinivas <vsrinivas@dragonflybsd.org>
7  * by Daniel Flores (GSOC 2013 - mentored by Matthew Dillon, compression)
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
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
17  *    the documentation and/or other materials provided with the
18  *    distribution.
19  * 3. Neither the name of The DragonFly Project nor the names of its
20  *    contributors may be used to endorse or promote products derived
21  *    from this software without specific, prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
26  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
27  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
28  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
29  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
31  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 /*
37  * This module handles low level logical file I/O (strategy) which backs
38  * the logical buffer cache.
39  *
40  * [De]compression, zero-block, check codes, and buffer cache operations
41  * for file data is handled here.
42  *
43  * Live dedup makes its home here as well.
44  */
45 
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
49 #include <sys/fcntl.h>
50 #include <sys/buf.h>
51 #include <sys/proc.h>
52 #include <sys/namei.h>
53 #include <sys/mount.h>
54 #include <sys/vnode.h>
55 #include <sys/mountctl.h>
56 #include <sys/dirent.h>
57 #include <sys/uio.h>
58 #include <sys/objcache.h>
59 #include <sys/event.h>
60 #include <sys/file.h>
61 #include <vfs/fifofs/fifo.h>
62 
63 #include "hammer2.h"
64 #include "hammer2_lz4.h"
65 
66 #include "zlib/hammer2_zlib.h"
67 
68 struct objcache *cache_buffer_read;
69 struct objcache *cache_buffer_write;
70 
71 /*
72  * Strategy code (async logical file buffer I/O from system)
73  *
74  * WARNING: The strategy code cannot safely use hammer2 transactions
75  *	    as this can deadlock against vfs_sync's vfsync() call
76  *	    if multiple flushes are queued.  All H2 structures must
77  *	    already be present and ready for the DIO.
78  *
79  *	    Reads can be initiated asynchronously, writes have to be
80  *	    spooled to a separate thread for action to avoid deadlocks.
81  */
82 static void hammer2_strategy_xop_read(hammer2_xop_t *arg, int clindex);
83 static void hammer2_strategy_xop_write(hammer2_xop_t *arg, int clindex);
84 static int hammer2_strategy_read(struct vop_strategy_args *ap);
85 static int hammer2_strategy_write(struct vop_strategy_args *ap);
86 static void hammer2_strategy_read_completion(hammer2_chain_t *chain,
87 				char *data, struct bio *bio);
88 
89 static void hammer2_dedup_record(hammer2_chain_t *chain, char *data);
90 static hammer2_off_t hammer2_dedup_lookup(hammer2_dev_t *hmp,
91 			char **datap, int pblksize);
92 
93 int
94 hammer2_vop_strategy(struct vop_strategy_args *ap)
95 {
96 	struct bio *biop;
97 	struct buf *bp;
98 	int error;
99 
100 	biop = ap->a_bio;
101 	bp = biop->bio_buf;
102 
103 	switch(bp->b_cmd) {
104 	case BUF_CMD_READ:
105 		error = hammer2_strategy_read(ap);
106 		++hammer2_iod_file_read;
107 		break;
108 	case BUF_CMD_WRITE:
109 		error = hammer2_strategy_write(ap);
110 		++hammer2_iod_file_write;
111 		break;
112 	default:
113 		bp->b_error = error = EINVAL;
114 		bp->b_flags |= B_ERROR;
115 		biodone(biop);
116 		break;
117 	}
118 	return (error);
119 }
120 
121 /*
122  * Return the largest contiguous physical disk range for the logical
123  * request, in bytes.
124  *
125  * (struct vnode *vp, off_t loffset, off_t *doffsetp, int *runp, int *runb)
126  *
127  * Basically disabled, the logical buffer write thread has to deal with
128  * buffers one-at-a-time.
129  */
130 int
131 hammer2_vop_bmap(struct vop_bmap_args *ap)
132 {
133 	*ap->a_doffsetp = NOOFFSET;
134 	if (ap->a_runp)
135 		*ap->a_runp = 0;
136 	if (ap->a_runb)
137 		*ap->a_runb = 0;
138 	return (EOPNOTSUPP);
139 }
140 
141 /****************************************************************************
142  *				READ SUPPORT				    *
143  ****************************************************************************/
144 /*
145  * Callback used in read path in case that a block is compressed with LZ4.
146  */
147 static
148 void
149 hammer2_decompress_LZ4_callback(const char *data, u_int bytes, struct bio *bio)
150 {
151 	struct buf *bp;
152 	char *compressed_buffer;
153 	int compressed_size;
154 	int result;
155 
156 	bp = bio->bio_buf;
157 
158 #if 0
159 	if bio->bio_caller_info2.index &&
160 	      bio->bio_caller_info1.uvalue32 !=
161 	      crc32(bp->b_data, bp->b_bufsize) --- return error
162 #endif
163 
164 	KKASSERT(bp->b_bufsize <= HAMMER2_PBUFSIZE);
165 	compressed_size = *(const int *)data;
166 	KKASSERT(compressed_size <= bytes - sizeof(int));
167 
168 	compressed_buffer = objcache_get(cache_buffer_read, M_INTWAIT);
169 	result = LZ4_decompress_safe(__DECONST(char *, &data[sizeof(int)]),
170 				     compressed_buffer,
171 				     compressed_size,
172 				     bp->b_bufsize);
173 	if (result < 0) {
174 		kprintf("READ PATH: Error during decompression."
175 			"bio %016jx/%d\n",
176 			(intmax_t)bio->bio_offset, bytes);
177 		/* make sure it isn't random garbage */
178 		bzero(compressed_buffer, bp->b_bufsize);
179 	}
180 	KKASSERT(result <= bp->b_bufsize);
181 	bcopy(compressed_buffer, bp->b_data, bp->b_bufsize);
182 	if (result < bp->b_bufsize)
183 		bzero(bp->b_data + result, bp->b_bufsize - result);
184 	objcache_put(cache_buffer_read, compressed_buffer);
185 	bp->b_resid = 0;
186 	bp->b_flags |= B_AGE;
187 }
188 
189 /*
190  * Callback used in read path in case that a block is compressed with ZLIB.
191  * It is almost identical to LZ4 callback, so in theory they can be unified,
192  * but we didn't want to make changes in bio structure for that.
193  */
194 static
195 void
196 hammer2_decompress_ZLIB_callback(const char *data, u_int bytes, struct bio *bio)
197 {
198 	struct buf *bp;
199 	char *compressed_buffer;
200 	z_stream strm_decompress;
201 	int result;
202 	int ret;
203 
204 	bp = bio->bio_buf;
205 
206 	KKASSERT(bp->b_bufsize <= HAMMER2_PBUFSIZE);
207 	strm_decompress.avail_in = 0;
208 	strm_decompress.next_in = Z_NULL;
209 
210 	ret = inflateInit(&strm_decompress);
211 
212 	if (ret != Z_OK)
213 		kprintf("HAMMER2 ZLIB: Fatal error in inflateInit.\n");
214 
215 	compressed_buffer = objcache_get(cache_buffer_read, M_INTWAIT);
216 	strm_decompress.next_in = __DECONST(char *, data);
217 
218 	/* XXX supply proper size, subset of device bp */
219 	strm_decompress.avail_in = bytes;
220 	strm_decompress.next_out = compressed_buffer;
221 	strm_decompress.avail_out = bp->b_bufsize;
222 
223 	ret = inflate(&strm_decompress, Z_FINISH);
224 	if (ret != Z_STREAM_END) {
225 		kprintf("HAMMER2 ZLIB: Fatar error during decompression.\n");
226 		bzero(compressed_buffer, bp->b_bufsize);
227 	}
228 	bcopy(compressed_buffer, bp->b_data, bp->b_bufsize);
229 	result = bp->b_bufsize - strm_decompress.avail_out;
230 	if (result < bp->b_bufsize)
231 		bzero(bp->b_data + result, strm_decompress.avail_out);
232 	objcache_put(cache_buffer_read, compressed_buffer);
233 	ret = inflateEnd(&strm_decompress);
234 
235 	bp->b_resid = 0;
236 	bp->b_flags |= B_AGE;
237 }
238 
239 /*
240  * Logical buffer I/O, async read.
241  */
242 static
243 int
244 hammer2_strategy_read(struct vop_strategy_args *ap)
245 {
246 	hammer2_xop_strategy_t *xop;
247 	struct buf *bp;
248 	struct bio *bio;
249 	struct bio *nbio;
250 	hammer2_inode_t *ip;
251 	hammer2_key_t lbase;
252 
253 	bio = ap->a_bio;
254 	bp = bio->bio_buf;
255 	ip = VTOI(ap->a_vp);
256 	nbio = push_bio(bio);
257 
258 	lbase = bio->bio_offset;
259 	KKASSERT(((int)lbase & HAMMER2_PBUFMASK) == 0);
260 
261 	xop = hammer2_xop_alloc(ip, 0);
262 	xop->finished = 0;
263 	xop->bio = bio;
264 	xop->lbase = lbase;
265 	hammer2_mtx_init(&xop->lock, "h2bio");
266 	hammer2_xop_start(&xop->head, hammer2_strategy_xop_read);
267 	/* asynchronous completion */
268 
269 	return(0);
270 }
271 
272 /*
273  * Per-node XOP (threaded), do a synchronous lookup of the chain and
274  * its data.  The frontend is asynchronous, so we are also responsible
275  * for racing to terminate the frontend.
276  */
277 static
278 void
279 hammer2_strategy_xop_read(hammer2_xop_t *arg, int clindex)
280 {
281 	hammer2_xop_strategy_t *xop = &arg->xop_strategy;
282 	hammer2_chain_t *parent;
283 	hammer2_chain_t *chain;
284 	hammer2_key_t key_dummy;
285 	hammer2_key_t lbase;
286 	struct bio *bio;
287 	struct buf *bp;
288 	int cache_index = -1;
289 	int error;
290 
291 	lbase = xop->lbase;
292 	bio = xop->bio;
293 	bp = bio->bio_buf;
294 
295 	parent = hammer2_inode_chain(xop->head.ip1, clindex,
296 				     HAMMER2_RESOLVE_ALWAYS |
297 				     HAMMER2_RESOLVE_SHARED);
298 	if (parent) {
299 		chain = hammer2_chain_lookup(&parent, &key_dummy,
300 					     lbase, lbase,
301 					     &cache_index,
302 					     HAMMER2_LOOKUP_ALWAYS |
303 					     HAMMER2_LOOKUP_SHARED);
304 		error = chain ? chain->error : 0;
305 	} else {
306 		error = EIO;
307 		chain = NULL;
308 	}
309 	error = hammer2_xop_feed(&xop->head, chain, clindex, error);
310 	if (chain) {
311 		hammer2_chain_unlock(chain);
312 		hammer2_chain_drop(chain);
313 	}
314 	if (parent) {
315 		hammer2_chain_unlock(parent);
316 		hammer2_chain_drop(parent);
317 	}
318 	chain = NULL;	/* safety */
319 	parent = NULL;	/* safety */
320 
321 	/*
322 	 * Race to finish the frontend
323 	 */
324 	if (xop->finished)
325 		return;
326 	hammer2_mtx_ex(&xop->lock);
327 	if (xop->finished) {
328 		hammer2_mtx_unlock(&xop->lock);
329 		return;
330 	}
331 
332 	/*
333 	 * Async operation has not completed and we now own the lock.
334 	 * Determine if we can complete the operation by issuing the
335 	 * frontend collection non-blocking.
336 	 */
337 	error = hammer2_xop_collect(&xop->head, HAMMER2_XOP_COLLECT_NOWAIT);
338 
339 	switch(error) {
340 	case 0:
341 		xop->finished = 1;
342 		hammer2_mtx_unlock(&xop->lock);
343 		chain = xop->head.cluster.focus;
344 		hammer2_strategy_read_completion(chain, (char *)chain->data,
345 						 xop->bio);
346 		hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
347 		biodone(bio);
348 		break;
349 	case ENOENT:
350 		xop->finished = 1;
351 		hammer2_mtx_unlock(&xop->lock);
352 		bp->b_resid = 0;
353 		bp->b_error = 0;
354 		bzero(bp->b_data, bp->b_bcount);
355 		biodone(bio);
356 		hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
357 		break;
358 	case EINPROGRESS:
359 		hammer2_mtx_unlock(&xop->lock);
360 		break;
361 	default:
362 		xop->finished = 1;
363 		hammer2_mtx_unlock(&xop->lock);
364 		bp->b_flags |= B_ERROR;
365 		bp->b_error = EIO;
366 		biodone(bio);
367 		hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
368 		break;
369 	}
370 }
371 
372 static
373 void
374 hammer2_strategy_read_completion(hammer2_chain_t *chain, char *data,
375 				 struct bio *bio)
376 {
377 	struct buf *bp = bio->bio_buf;
378 
379 	if (chain->bref.type == HAMMER2_BREF_TYPE_INODE) {
380 		/*
381 		 * Data is embedded in the inode (copy from inode).
382 		 */
383 		bcopy(((hammer2_inode_data_t *)data)->u.data,
384 		      bp->b_data, HAMMER2_EMBEDDED_BYTES);
385 		bzero(bp->b_data + HAMMER2_EMBEDDED_BYTES,
386 		      bp->b_bcount - HAMMER2_EMBEDDED_BYTES);
387 		bp->b_resid = 0;
388 		bp->b_error = 0;
389 	} else if (chain->bref.type == HAMMER2_BREF_TYPE_DATA) {
390 		/*
391 		 * Data is on-media, record for live dedup.
392 		 */
393 		hammer2_dedup_record(chain, data);
394 
395 		/*
396 		 * Decopmression and copy.
397 		 */
398 		switch (HAMMER2_DEC_COMP(chain->bref.methods)) {
399 		case HAMMER2_COMP_LZ4:
400 			hammer2_decompress_LZ4_callback(data, chain->bytes,
401 							bio);
402 			break;
403 		case HAMMER2_COMP_ZLIB:
404 			hammer2_decompress_ZLIB_callback(data, chain->bytes,
405 							 bio);
406 			break;
407 		case HAMMER2_COMP_NONE:
408 			KKASSERT(chain->bytes <= bp->b_bcount);
409 			bcopy(data, bp->b_data, chain->bytes);
410 			if (chain->bytes < bp->b_bcount) {
411 				bzero(bp->b_data + chain->bytes,
412 				      bp->b_bcount - chain->bytes);
413 			}
414 			bp->b_flags |= B_NOTMETA;
415 			bp->b_resid = 0;
416 			bp->b_error = 0;
417 			break;
418 		default:
419 			panic("hammer2_strategy_read: "
420 			      "unknown compression type");
421 		}
422 	} else {
423 		panic("hammer2_strategy_read: unknown bref type");
424 	}
425 }
426 
427 /****************************************************************************
428  *				WRITE SUPPORT				    *
429  ****************************************************************************/
430 
431 /*
432  * Functions for compression in threads,
433  * from hammer2_vnops.c
434  */
435 static void hammer2_write_file_core(struct buf *bp, hammer2_inode_t *ip,
436 				hammer2_chain_t **parentp,
437 				hammer2_key_t lbase, int ioflag, int pblksize,
438 				hammer2_tid_t mtid, int *errorp);
439 static void hammer2_compress_and_write(struct buf *bp, hammer2_inode_t *ip,
440 				hammer2_chain_t **parentp,
441 				hammer2_key_t lbase, int ioflag, int pblksize,
442 				hammer2_tid_t mtid, int *errorp,
443 				int comp_algo, int check_algo);
444 static void hammer2_zero_check_and_write(struct buf *bp, hammer2_inode_t *ip,
445 				hammer2_chain_t **parentp,
446 				hammer2_key_t lbase, int ioflag, int pblksize,
447 				hammer2_tid_t mtid, int *errorp,
448 				int check_algo);
449 static int test_block_zeros(const char *buf, size_t bytes);
450 static void zero_write(struct buf *bp, hammer2_inode_t *ip,
451 				hammer2_chain_t **parentp,
452 				hammer2_key_t lbase,
453 				hammer2_tid_t mtid, int *errorp);
454 static void hammer2_write_bp(hammer2_chain_t *chain, struct buf *bp,
455 				int ioflag, int pblksize,
456 				hammer2_tid_t mtid, int *errorp,
457 				int check_algo);
458 
459 static
460 int
461 hammer2_strategy_write(struct vop_strategy_args *ap)
462 {
463 	hammer2_xop_strategy_t *xop;
464 	hammer2_pfs_t *pmp;
465 	struct bio *bio;
466 	struct buf *bp;
467 	hammer2_inode_t *ip;
468 
469 	bio = ap->a_bio;
470 	bp = bio->bio_buf;
471 	ip = VTOI(ap->a_vp);
472 	pmp = ip->pmp;
473 
474 	hammer2_lwinprog_ref(pmp);
475 	hammer2_trans_assert_strategy(pmp);
476 
477 	xop = hammer2_xop_alloc(ip, HAMMER2_XOP_MODIFYING);
478 	xop->finished = 0;
479 	xop->bio = bio;
480 	xop->lbase = bio->bio_offset;
481 	hammer2_xop_start(&xop->head, hammer2_strategy_xop_write);
482 	/* asynchronous completion */
483 
484 	hammer2_lwinprog_wait(pmp, hammer2_flush_pipe);
485 
486 	return(0);
487 }
488 
489 /*
490  * Per-node XOP (threaded).  Write the logical buffer to the media.
491  */
492 static
493 void
494 hammer2_strategy_xop_write(hammer2_xop_t *arg, int clindex)
495 {
496 	hammer2_xop_strategy_t *xop = &arg->xop_strategy;
497 	hammer2_chain_t *parent;
498 	hammer2_key_t lbase;
499 	hammer2_inode_t *ip;
500 	struct bio *bio;
501 	struct buf *bp;
502 	int error;
503 	int lblksize;
504 	int pblksize;
505 
506 	lbase = xop->lbase;
507 	bio = xop->bio;
508 	bp = bio->bio_buf;
509 	ip = xop->head.ip1;
510 
511 	/* hammer2_trans_init(parent->hmp->spmp, HAMMER2_TRANS_BUFCACHE); */
512 
513 	lblksize = hammer2_calc_logical(ip, bio->bio_offset, &lbase, NULL);
514 	pblksize = hammer2_calc_physical(ip, lbase);
515 	parent = hammer2_inode_chain(ip, clindex, HAMMER2_RESOLVE_ALWAYS);
516 	hammer2_write_file_core(bp, ip, &parent,
517 				lbase, IO_ASYNC, pblksize,
518 				xop->head.mtid, &error);
519 	if (parent) {
520 		hammer2_chain_unlock(parent);
521 		hammer2_chain_drop(parent);
522 		parent = NULL;	/* safety */
523 	}
524 	error = hammer2_xop_feed(&xop->head, NULL, clindex, error);
525 
526 	/*
527 	 * Race to finish the frontend
528 	 */
529 	if (xop->finished)
530 		return;
531 	hammer2_mtx_ex(&xop->lock);
532 	if (xop->finished) {
533 		hammer2_mtx_unlock(&xop->lock);
534 		return;
535 	}
536 
537 	/*
538 	 * Async operation has not completed and we now own the lock.
539 	 * Determine if we can complete the operation by issuing the
540 	 * frontend collection non-blocking.
541 	 */
542 	error = hammer2_xop_collect(&xop->head, HAMMER2_XOP_COLLECT_NOWAIT);
543 
544 	switch(error) {
545 	case ENOENT:
546 	case 0:
547 		xop->finished = 1;
548 		hammer2_mtx_unlock(&xop->lock);
549 		bp->b_resid = 0;
550 		bp->b_error = 0;
551 		biodone(bio);
552 		hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
553 		hammer2_lwinprog_drop(ip->pmp);
554 		break;
555 	case EINPROGRESS:
556 		hammer2_mtx_unlock(&xop->lock);
557 		break;
558 	default:
559 		xop->finished = 1;
560 		hammer2_mtx_unlock(&xop->lock);
561 		bp->b_flags |= B_ERROR;
562 		bp->b_error = EIO;
563 		biodone(bio);
564 		hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
565 		hammer2_lwinprog_drop(ip->pmp);
566 		break;
567 	}
568 }
569 
570 /*
571  * Wait for pending I/O to complete
572  */
573 void
574 hammer2_bioq_sync(hammer2_pfs_t *pmp)
575 {
576 	hammer2_lwinprog_wait(pmp, 0);
577 }
578 
579 /*
580  * Create a new cluster at (cparent, lbase) and assign physical storage,
581  * returning a cluster suitable for I/O.  The cluster will be in a modified
582  * state.
583  *
584  * cparent can wind up being anything.
585  *
586  * If datap is not NULL, *datap points to the real data we intend to write.
587  * If we can dedup the storage location we set *datap to NULL to indicate
588  * to the caller that a dedup occurred.
589  *
590  * NOTE: Special case for data embedded in inode.
591  */
592 static
593 hammer2_chain_t *
594 hammer2_assign_physical(hammer2_inode_t *ip, hammer2_chain_t **parentp,
595 			hammer2_key_t lbase, int pblksize,
596 			hammer2_tid_t mtid, char **datap, int *errorp)
597 {
598 	hammer2_chain_t *chain;
599 	hammer2_key_t key_dummy;
600 	hammer2_off_t dedup_off;
601 	int pradix = hammer2_getradix(pblksize);
602 	int cache_index = -1;
603 
604 	/*
605 	 * Locate the chain associated with lbase, return a locked chain.
606 	 * However, do not instantiate any data reference (which utilizes a
607 	 * device buffer) because we will be using direct IO via the
608 	 * logical buffer cache buffer.
609 	 */
610 	*errorp = 0;
611 	KKASSERT(pblksize >= HAMMER2_ALLOC_MIN);
612 retry:
613 	chain = hammer2_chain_lookup(parentp, &key_dummy,
614 				     lbase, lbase,
615 				     &cache_index,
616 				     HAMMER2_LOOKUP_NODATA);
617 	if (chain == NULL) {
618 		/*
619 		 * We found a hole, create a new chain entry.
620 		 *
621 		 * NOTE: DATA chains are created without device backing
622 		 *	 store (nor do we want any).
623 		 */
624 		dedup_off = hammer2_dedup_lookup((*parentp)->hmp, datap,
625 						 pblksize);
626 		*errorp = hammer2_chain_create(parentp, &chain, ip->pmp,
627 					       lbase, HAMMER2_PBUFRADIX,
628 					       HAMMER2_BREF_TYPE_DATA,
629 					       pblksize, mtid,
630 					       dedup_off, 0);
631 		if (chain == NULL) {
632 			panic("hammer2_chain_create: par=%p error=%d\n",
633 			      *parentp, *errorp);
634 			goto retry;
635 		}
636 		/*ip->delta_dcount += pblksize;*/
637 	} else {
638 		switch (chain->bref.type) {
639 		case HAMMER2_BREF_TYPE_INODE:
640 			/*
641 			 * The data is embedded in the inode, which requires
642 			 * a bit more finess.
643 			 */
644 			hammer2_chain_modify_ip(ip, chain, mtid, 0);
645 			break;
646 		case HAMMER2_BREF_TYPE_DATA:
647 			dedup_off = hammer2_dedup_lookup(chain->hmp, datap,
648 							 pblksize);
649 			if (chain->bytes != pblksize) {
650 				hammer2_chain_resize(ip, *parentp, chain,
651 						     mtid, dedup_off,
652 						     pradix,
653 						     HAMMER2_MODIFY_OPTDATA);
654 			}
655 
656 			/*
657 			 * DATA buffers must be marked modified whether the
658 			 * data is in a logical buffer or not.  We also have
659 			 * to make this call to fixup the chain data pointers
660 			 * after resizing in case this is an encrypted or
661 			 * compressed buffer.
662 			 */
663 			hammer2_chain_modify(chain, mtid, dedup_off,
664 					     HAMMER2_MODIFY_OPTDATA);
665 			break;
666 		default:
667 			panic("hammer2_assign_physical: bad type");
668 			/* NOT REACHED */
669 			break;
670 		}
671 	}
672 	return (chain);
673 }
674 
675 /*
676  * hammer2_write_file_core() - hammer2_write_thread() helper
677  *
678  * The core write function which determines which path to take
679  * depending on compression settings.  We also have to locate the
680  * related chains so we can calculate and set the check data for
681  * the blockref.
682  */
683 static
684 void
685 hammer2_write_file_core(struct buf *bp, hammer2_inode_t *ip,
686 			hammer2_chain_t **parentp,
687 			hammer2_key_t lbase, int ioflag, int pblksize,
688 			hammer2_tid_t mtid, int *errorp)
689 {
690 	hammer2_chain_t *chain;
691 	char *data = bp->b_data;
692 
693 	switch(HAMMER2_DEC_ALGO(ip->meta.comp_algo)) {
694 	case HAMMER2_COMP_NONE:
695 		/*
696 		 * We have to assign physical storage to the buffer
697 		 * we intend to dirty or write now to avoid deadlocks
698 		 * in the strategy code later.
699 		 *
700 		 * This can return NOOFFSET for inode-embedded data.
701 		 * The strategy code will take care of it in that case.
702 		 */
703 		chain = hammer2_assign_physical(ip, parentp, lbase, pblksize,
704 						mtid, &data, errorp);
705 		if (chain->bref.type == HAMMER2_BREF_TYPE_INODE) {
706 			hammer2_inode_data_t *wipdata;
707 
708 			wipdata = &chain->data->ipdata;
709 			KKASSERT(wipdata->meta.op_flags &
710 				 HAMMER2_OPFLAG_DIRECTDATA);
711 			KKASSERT(bp->b_loffset == 0);
712 			bcopy(bp->b_data, wipdata->u.data,
713 			      HAMMER2_EMBEDDED_BYTES);
714 			++hammer2_iod_file_wembed;
715 		} else if (data == NULL) {
716 			/*
717 			 * Copy of data already present on-media.
718 			 */
719 			chain->bref.methods =
720 				HAMMER2_ENC_COMP(HAMMER2_COMP_NONE) +
721 				HAMMER2_ENC_CHECK(ip->meta.check_algo);
722 			hammer2_chain_setcheck(chain, bp->b_data);
723 		} else {
724 			hammer2_write_bp(chain, bp, ioflag, pblksize,
725 					 mtid, errorp, ip->meta.check_algo);
726 		}
727 		if (chain) {
728 			hammer2_chain_unlock(chain);
729 			hammer2_chain_drop(chain);
730 		}
731 		break;
732 	case HAMMER2_COMP_AUTOZERO:
733 		/*
734 		 * Check for zero-fill only
735 		 */
736 		hammer2_zero_check_and_write(bp, ip, parentp,
737 					     lbase, ioflag, pblksize,
738 					     mtid, errorp,
739 					     ip->meta.check_algo);
740 		break;
741 	case HAMMER2_COMP_LZ4:
742 	case HAMMER2_COMP_ZLIB:
743 	default:
744 		/*
745 		 * Check for zero-fill and attempt compression.
746 		 */
747 		hammer2_compress_and_write(bp, ip, parentp,
748 					   lbase, ioflag, pblksize,
749 					   mtid, errorp,
750 					   ip->meta.comp_algo,
751 					   ip->meta.check_algo);
752 		break;
753 	}
754 }
755 
756 /*
757  * Helper
758  *
759  * Generic function that will perform the compression in compression
760  * write path. The compression algorithm is determined by the settings
761  * obtained from inode.
762  */
763 static
764 void
765 hammer2_compress_and_write(struct buf *bp, hammer2_inode_t *ip,
766 	hammer2_chain_t **parentp,
767 	hammer2_key_t lbase, int ioflag, int pblksize,
768 	hammer2_tid_t mtid, int *errorp, int comp_algo, int check_algo)
769 {
770 	hammer2_chain_t *chain;
771 	int comp_size;
772 	int comp_block_size;
773 	char *comp_buffer;
774 	char *data;
775 
776 	if (test_block_zeros(bp->b_data, pblksize)) {
777 		zero_write(bp, ip, parentp, lbase, mtid, errorp);
778 		return;
779 	}
780 
781 	comp_size = 0;
782 	comp_buffer = NULL;
783 
784 	KKASSERT(pblksize / 2 <= 32768);
785 
786 	if (ip->comp_heuristic < 8 || (ip->comp_heuristic & 7) == 0) {
787 		z_stream strm_compress;
788 		int comp_level;
789 		int ret;
790 
791 		switch(HAMMER2_DEC_ALGO(comp_algo)) {
792 		case HAMMER2_COMP_LZ4:
793 			comp_buffer = objcache_get(cache_buffer_write,
794 						   M_INTWAIT);
795 			comp_size = LZ4_compress_limitedOutput(
796 					bp->b_data,
797 					&comp_buffer[sizeof(int)],
798 					pblksize,
799 					pblksize / 2 - sizeof(int));
800 			/*
801 			 * We need to prefix with the size, LZ4
802 			 * doesn't do it for us.  Add the related
803 			 * overhead.
804 			 */
805 			*(int *)comp_buffer = comp_size;
806 			if (comp_size)
807 				comp_size += sizeof(int);
808 			break;
809 		case HAMMER2_COMP_ZLIB:
810 			comp_level = HAMMER2_DEC_LEVEL(comp_algo);
811 			if (comp_level == 0)
812 				comp_level = 6;	/* default zlib compression */
813 			else if (comp_level < 6)
814 				comp_level = 6;
815 			else if (comp_level > 9)
816 				comp_level = 9;
817 			ret = deflateInit(&strm_compress, comp_level);
818 			if (ret != Z_OK) {
819 				kprintf("HAMMER2 ZLIB: fatal error "
820 					"on deflateInit.\n");
821 			}
822 
823 			comp_buffer = objcache_get(cache_buffer_write,
824 						   M_INTWAIT);
825 			strm_compress.next_in = bp->b_data;
826 			strm_compress.avail_in = pblksize;
827 			strm_compress.next_out = comp_buffer;
828 			strm_compress.avail_out = pblksize / 2;
829 			ret = deflate(&strm_compress, Z_FINISH);
830 			if (ret == Z_STREAM_END) {
831 				comp_size = pblksize / 2 -
832 					    strm_compress.avail_out;
833 			} else {
834 				comp_size = 0;
835 			}
836 			ret = deflateEnd(&strm_compress);
837 			break;
838 		default:
839 			kprintf("Error: Unknown compression method.\n");
840 			kprintf("Comp_method = %d.\n", comp_algo);
841 			break;
842 		}
843 	}
844 
845 	if (comp_size == 0) {
846 		/*
847 		 * compression failed or turned off
848 		 */
849 		comp_block_size = pblksize;	/* safety */
850 		if (++ip->comp_heuristic > 128)
851 			ip->comp_heuristic = 8;
852 	} else {
853 		/*
854 		 * compression succeeded
855 		 */
856 		ip->comp_heuristic = 0;
857 		if (comp_size <= 1024) {
858 			comp_block_size = 1024;
859 		} else if (comp_size <= 2048) {
860 			comp_block_size = 2048;
861 		} else if (comp_size <= 4096) {
862 			comp_block_size = 4096;
863 		} else if (comp_size <= 8192) {
864 			comp_block_size = 8192;
865 		} else if (comp_size <= 16384) {
866 			comp_block_size = 16384;
867 		} else if (comp_size <= 32768) {
868 			comp_block_size = 32768;
869 		} else {
870 			panic("hammer2: WRITE PATH: "
871 			      "Weird comp_size value.");
872 			/* NOT REACHED */
873 			comp_block_size = pblksize;
874 		}
875 
876 		/*
877 		 * Must zero the remainder or dedup (which operates on a
878 		 * physical block basis) will not find matches.
879 		 */
880 		if (comp_size < comp_block_size) {
881 			bzero(comp_buffer + comp_size,
882 			      comp_block_size - comp_size);
883 		}
884 	}
885 
886 	/*
887 	 * Assign physical storage, data will be set to NULL if a live-dedup
888 	 * was successful.
889 	 */
890 	data = comp_size ? comp_buffer : bp->b_data;
891 	chain = hammer2_assign_physical(ip, parentp, lbase, comp_block_size,
892 					mtid, &data, errorp);
893 
894 	if (*errorp) {
895 		kprintf("WRITE PATH: An error occurred while "
896 			"assigning physical space.\n");
897 		KKASSERT(chain == NULL);
898 		goto done;
899 	}
900 
901 	if (chain->bref.type == HAMMER2_BREF_TYPE_INODE) {
902 		hammer2_inode_data_t *wipdata;
903 
904 		hammer2_chain_modify_ip(ip, chain, mtid, 0);
905 		wipdata = &chain->data->ipdata;
906 		KKASSERT(wipdata->meta.op_flags & HAMMER2_OPFLAG_DIRECTDATA);
907 		KKASSERT(bp->b_loffset == 0);
908 		bcopy(bp->b_data, wipdata->u.data, HAMMER2_EMBEDDED_BYTES);
909 		++hammer2_iod_file_wembed;
910 	} else if (data == NULL) {
911 		/*
912 		 * Live deduplication, a copy of the data is already present
913 		 * on the media.
914 		 */
915 		char *bdata;
916 
917 		if (comp_size) {
918 			chain->bref.methods =
919 				HAMMER2_ENC_COMP(comp_algo) +
920 				HAMMER2_ENC_CHECK(check_algo);
921 		} else {
922 			chain->bref.methods =
923 				HAMMER2_ENC_COMP(
924 					HAMMER2_COMP_NONE) +
925 				HAMMER2_ENC_CHECK(check_algo);
926 		}
927 		bdata = comp_size ? comp_buffer : bp->b_data;
928 		hammer2_chain_setcheck(chain, bdata);
929 		atomic_clear_int(&chain->flags, HAMMER2_CHAIN_INITIAL);
930 	} else {
931 		hammer2_io_t *dio;
932 		char *bdata;
933 
934 		KKASSERT(chain->flags & HAMMER2_CHAIN_MODIFIED);
935 
936 		switch(chain->bref.type) {
937 		case HAMMER2_BREF_TYPE_INODE:
938 			panic("hammer2_write_bp: unexpected inode\n");
939 			break;
940 		case HAMMER2_BREF_TYPE_DATA:
941 			/*
942 			 * Optimize out the read-before-write
943 			 * if possible.
944 			 */
945 			*errorp = hammer2_io_newnz(chain->hmp,
946 						   chain->bref.data_off,
947 						   chain->bytes,
948 						   &dio);
949 			if (*errorp) {
950 				hammer2_io_brelse(&dio);
951 				kprintf("hammer2: WRITE PATH: "
952 					"dbp bread error\n");
953 				break;
954 			}
955 			bdata = hammer2_io_data(dio, chain->bref.data_off);
956 
957 			/*
958 			 * When loading the block make sure we don't
959 			 * leave garbage after the compressed data.
960 			 */
961 			if (comp_size) {
962 				chain->bref.methods =
963 					HAMMER2_ENC_COMP(comp_algo) +
964 					HAMMER2_ENC_CHECK(check_algo);
965 				bcopy(comp_buffer, bdata, comp_size);
966 			} else {
967 				chain->bref.methods =
968 					HAMMER2_ENC_COMP(
969 						HAMMER2_COMP_NONE) +
970 					HAMMER2_ENC_CHECK(check_algo);
971 				bcopy(bp->b_data, bdata, pblksize);
972 			}
973 
974 			/*
975 			 * The flush code doesn't calculate check codes for
976 			 * file data (doing so can result in excessive I/O),
977 			 * so we do it here.
978 			 *
979 			 * Record for dedup only after the DIO's buffer cache
980 			 * buffer has been updated.
981 			 */
982 			hammer2_chain_setcheck(chain, bdata);
983 			hammer2_dedup_record(chain, bdata);
984 
985 			/*
986 			 * Device buffer is now valid, chain is no longer in
987 			 * the initial state.
988 			 *
989 			 * (No blockref table worries with file data)
990 			 */
991 			atomic_clear_int(&chain->flags, HAMMER2_CHAIN_INITIAL);
992 
993 			/* Now write the related bdp. */
994 			if (ioflag & IO_SYNC) {
995 				/*
996 				 * Synchronous I/O requested.
997 				 */
998 				hammer2_io_bwrite(&dio);
999 			/*
1000 			} else if ((ioflag & IO_DIRECT) &&
1001 				   loff + n == pblksize) {
1002 				hammer2_io_bdwrite(&dio);
1003 			*/
1004 			} else if (ioflag & IO_ASYNC) {
1005 				hammer2_io_bawrite(&dio);
1006 			} else {
1007 				hammer2_io_bdwrite(&dio);
1008 			}
1009 			break;
1010 		default:
1011 			panic("hammer2_write_bp: bad chain type %d\n",
1012 				chain->bref.type);
1013 			/* NOT REACHED */
1014 			break;
1015 		}
1016 	}
1017 done:
1018 	if (chain) {
1019 		hammer2_chain_unlock(chain);
1020 		hammer2_chain_drop(chain);
1021 	}
1022 	if (comp_buffer)
1023 		objcache_put(cache_buffer_write, comp_buffer);
1024 }
1025 
1026 /*
1027  * Helper
1028  *
1029  * Function that performs zero-checking and writing without compression,
1030  * it corresponds to default zero-checking path.
1031  */
1032 static
1033 void
1034 hammer2_zero_check_and_write(struct buf *bp, hammer2_inode_t *ip,
1035 	hammer2_chain_t **parentp,
1036 	hammer2_key_t lbase, int ioflag, int pblksize,
1037 	hammer2_tid_t mtid, int *errorp,
1038 	int check_algo)
1039 {
1040 	hammer2_chain_t *chain;
1041 	char *data = bp->b_data;
1042 
1043 	if (test_block_zeros(bp->b_data, pblksize)) {
1044 		zero_write(bp, ip, parentp, lbase, mtid, errorp);
1045 	} else {
1046 		chain = hammer2_assign_physical(ip, parentp, lbase, pblksize,
1047 						mtid, &data, errorp);
1048 		if (data) {
1049 			hammer2_write_bp(chain, bp, ioflag, pblksize,
1050 					 mtid, errorp, check_algo);
1051 		} /* else dedup occurred */
1052 		if (chain) {
1053 			hammer2_chain_unlock(chain);
1054 			hammer2_chain_drop(chain);
1055 		}
1056 	}
1057 }
1058 
1059 /*
1060  * Helper
1061  *
1062  * A function to test whether a block of data contains only zeros,
1063  * returns TRUE (non-zero) if the block is all zeros.
1064  */
1065 static
1066 int
1067 test_block_zeros(const char *buf, size_t bytes)
1068 {
1069 	size_t i;
1070 
1071 	for (i = 0; i < bytes; i += sizeof(long)) {
1072 		if (*(const long *)(buf + i) != 0)
1073 			return (0);
1074 	}
1075 	return (1);
1076 }
1077 
1078 /*
1079  * Helper
1080  *
1081  * Function to "write" a block that contains only zeros.
1082  */
1083 static
1084 void
1085 zero_write(struct buf *bp, hammer2_inode_t *ip,
1086 	   hammer2_chain_t **parentp,
1087 	   hammer2_key_t lbase, hammer2_tid_t mtid, int *errorp __unused)
1088 {
1089 	hammer2_chain_t *chain;
1090 	hammer2_key_t key_dummy;
1091 	int cache_index = -1;
1092 
1093 	chain = hammer2_chain_lookup(parentp, &key_dummy,
1094 				     lbase, lbase,
1095 				     &cache_index,
1096 				     HAMMER2_LOOKUP_NODATA);
1097 	if (chain) {
1098 		if (chain->bref.type == HAMMER2_BREF_TYPE_INODE) {
1099 			hammer2_inode_data_t *wipdata;
1100 
1101 			hammer2_chain_modify_ip(ip, chain, mtid, 0);
1102 			wipdata = &chain->data->ipdata;
1103 			KKASSERT(wipdata->meta.op_flags &
1104 				 HAMMER2_OPFLAG_DIRECTDATA);
1105 			KKASSERT(bp->b_loffset == 0);
1106 			bzero(wipdata->u.data, HAMMER2_EMBEDDED_BYTES);
1107 			++hammer2_iod_file_wembed;
1108 		} else {
1109 			hammer2_chain_delete(*parentp, chain,
1110 					     mtid, HAMMER2_DELETE_PERMANENT);
1111 			++hammer2_iod_file_wzero;
1112 		}
1113 		hammer2_chain_unlock(chain);
1114 		hammer2_chain_drop(chain);
1115 	} else {
1116 		++hammer2_iod_file_wzero;
1117 	}
1118 }
1119 
1120 /*
1121  * Helper
1122  *
1123  * Function to write the data as it is, without performing any sort of
1124  * compression. This function is used in path without compression and
1125  * default zero-checking path.
1126  */
1127 static
1128 void
1129 hammer2_write_bp(hammer2_chain_t *chain, struct buf *bp, int ioflag,
1130 		 int pblksize,
1131 		 hammer2_tid_t mtid, int *errorp, int check_algo)
1132 {
1133 	hammer2_inode_data_t *wipdata;
1134 	hammer2_io_t *dio;
1135 	char *bdata;
1136 	int error;
1137 
1138 	error = 0;	/* XXX TODO below */
1139 
1140 	KKASSERT(chain->flags & HAMMER2_CHAIN_MODIFIED);
1141 
1142 	switch(chain->bref.type) {
1143 	case HAMMER2_BREF_TYPE_INODE:
1144 		wipdata = &chain->data->ipdata;
1145 		KKASSERT(wipdata->meta.op_flags & HAMMER2_OPFLAG_DIRECTDATA);
1146 		KKASSERT(bp->b_loffset == 0);
1147 		bcopy(bp->b_data, wipdata->u.data, HAMMER2_EMBEDDED_BYTES);
1148 		error = 0;
1149 		++hammer2_iod_file_wembed;
1150 		break;
1151 	case HAMMER2_BREF_TYPE_DATA:
1152 		error = hammer2_io_newnz(chain->hmp,
1153 					 chain->bref.data_off,
1154 					 chain->bytes, &dio);
1155 		if (error) {
1156 			hammer2_io_bqrelse(&dio);
1157 			kprintf("hammer2: WRITE PATH: "
1158 				"dbp bread error\n");
1159 			break;
1160 		}
1161 		bdata = hammer2_io_data(dio, chain->bref.data_off);
1162 
1163 		chain->bref.methods = HAMMER2_ENC_COMP(HAMMER2_COMP_NONE) +
1164 				      HAMMER2_ENC_CHECK(check_algo);
1165 		bcopy(bp->b_data, bdata, chain->bytes);
1166 
1167 		/*
1168 		 * The flush code doesn't calculate check codes for
1169 		 * file data (doing so can result in excessive I/O),
1170 		 * so we do it here.
1171 		 *
1172 		 * Record for dedup only after the DIO's buffer cache
1173 		 * buffer has been updated.
1174 		 */
1175 		hammer2_chain_setcheck(chain, bdata);
1176 		hammer2_dedup_record(chain, bdata);
1177 
1178 		/*
1179 		 * Device buffer is now valid, chain is no longer in
1180 		 * the initial state.
1181 		 *
1182 		 * (No blockref table worries with file data)
1183 		 */
1184 		atomic_clear_int(&chain->flags, HAMMER2_CHAIN_INITIAL);
1185 
1186 		if (ioflag & IO_SYNC) {
1187 			/*
1188 			 * Synchronous I/O requested.
1189 			 */
1190 			hammer2_io_bwrite(&dio);
1191 		/*
1192 		} else if ((ioflag & IO_DIRECT) &&
1193 			   loff + n == pblksize) {
1194 			hammer2_io_bdwrite(&dio);
1195 		*/
1196 		} else if (ioflag & IO_ASYNC) {
1197 			hammer2_io_bawrite(&dio);
1198 		} else {
1199 			hammer2_io_bdwrite(&dio);
1200 		}
1201 		break;
1202 	default:
1203 		panic("hammer2_write_bp: bad chain type %d\n",
1204 		      chain->bref.type);
1205 		/* NOT REACHED */
1206 		error = 0;
1207 		break;
1208 	}
1209 	KKASSERT(error == 0);	/* XXX TODO */
1210 	*errorp = error;
1211 }
1212 
1213 /*
1214  * LIVE DEDUP HEURISTIC
1215  *
1216  * WARNING! This code is SMP safe but the heuristic allows SMP collisions.
1217  *	    All fields must be loaded into locals and validated.
1218  */
1219 static
1220 void
1221 hammer2_dedup_record(hammer2_chain_t *chain, char *data)
1222 {
1223 	hammer2_dev_t *hmp;
1224 	hammer2_dedup_t *dedup;
1225 	int32_t crc;
1226 	int best = 0;
1227 	int i;
1228 	int dticks;
1229 
1230 	hmp = chain->hmp;
1231 	crc = hammer2_icrc32(data, chain->bytes);
1232 	dedup = &hmp->heur_dedup[crc & (HAMMER2_DEDUP_HEUR_MASK & ~3)];
1233 	for (i = 0; i < 4; ++i) {
1234 		if (dedup[i].data_crc == crc) {
1235 			best = i;
1236 			break;
1237 		}
1238 		dticks = (int)(dedup[i].ticks - dedup[best].ticks);
1239 		if (dticks < 0 || dticks > hz * 60 * 30)
1240 			best = i;
1241 	}
1242 	dedup += best;
1243 	if (hammer2_debug & 0x40000) {
1244 		kprintf("REC %04x %08x %016jx\n",
1245 			(int)(dedup - hmp->heur_dedup),
1246 			crc,
1247 			chain->bref.data_off);
1248 	}
1249 	dedup->ticks = ticks;
1250 	dedup->data_off = chain->bref.data_off;
1251 	dedup->data_crc = crc;
1252 	atomic_set_int(&chain->flags, HAMMER2_CHAIN_DEDUP);
1253 }
1254 
1255 static
1256 hammer2_off_t
1257 hammer2_dedup_lookup(hammer2_dev_t *hmp, char **datap, int pblksize)
1258 {
1259 	hammer2_dedup_t *dedup;
1260 	hammer2_io_t *dio;
1261 	hammer2_off_t off;
1262 	uint32_t crc;
1263 	char *data;
1264 	int i;
1265 
1266 	data = *datap;
1267 	if (data == NULL)
1268 		return 0;
1269 
1270 	crc = hammer2_icrc32(data, pblksize);
1271 	dedup = &hmp->heur_dedup[crc & (HAMMER2_DEDUP_HEUR_MASK & ~3)];
1272 
1273 	if (hammer2_debug & 0x40000) {
1274 		kprintf("LOC %04x/4 %08x\n",
1275 			(int)(dedup - hmp->heur_dedup),
1276 			crc);
1277 	}
1278 
1279 	for (i = 0; i < 4; ++i) {
1280 		off = dedup[i].data_off;
1281 		cpu_ccfence();
1282 		if (dedup[i].data_crc != crc)
1283 			continue;
1284 		if ((1 << (int)(off & HAMMER2_OFF_MASK_RADIX)) != pblksize)
1285 			continue;
1286 		dio = hammer2_io_getquick(hmp, off, pblksize);
1287 		if (dio &&
1288 		    bcmp(data, hammer2_io_data(dio, off), pblksize) == 0) {
1289 			if (hammer2_debug & 0x40000) {
1290 				kprintf("DEDUP SUCCESS %016jx\n",
1291 					(intmax_t)off);
1292 			}
1293 			hammer2_io_putblk(&dio);
1294 			*datap = NULL;
1295 			dedup[i].ticks = ticks;	/* update use */
1296 			++hammer2_iod_file_wdedup;
1297 			return off;		/* RETURN */
1298 		}
1299 		if (dio)
1300 			hammer2_io_putblk(&dio);
1301 	}
1302 	return 0;
1303 }
1304 
1305 /*
1306  * Poof.  Races are ok, if someone gets in and reuses a dedup offset
1307  * before or while we are clearing it they will also recover the freemap
1308  * entry (set it to fully allocated), so a bulkfree race can only set it
1309  * to a possibly-free state.
1310  *
1311  * XXX ok, well, not really sure races are ok but going to run with it
1312  *     for the moment.
1313  */
1314 void
1315 hammer2_dedup_clear(hammer2_dev_t *hmp)
1316 {
1317 	int i;
1318 
1319 	for (i = 0; i < HAMMER2_DEDUP_HEUR_SIZE; ++i) {
1320 		hmp->heur_dedup[i].data_off = 0;
1321 		hmp->heur_dedup[i].ticks = ticks - 1;
1322 	}
1323 }
1324