xref: /dragonfly/sys/vfs/hammer2/hammer2_freemap.c (revision d37f73b6)
1 /*
2  * Copyright (c) 2011-2014 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  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in
16  *    the documentation and/or other materials provided with the
17  *    distribution.
18  * 3. Neither the name of The DragonFly Project nor the names of its
19  *    contributors may be used to endorse or promote products derived
20  *    from this software without specific, prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/kernel.h>
38 #include <sys/fcntl.h>
39 #include <sys/buf.h>
40 #include <sys/proc.h>
41 #include <sys/namei.h>
42 #include <sys/mount.h>
43 #include <sys/vnode.h>
44 #include <sys/mountctl.h>
45 
46 #include "hammer2.h"
47 
48 #define FREEMAP_DEBUG	0
49 
50 struct hammer2_fiterate {
51 	hammer2_off_t	bpref;
52 	hammer2_off_t	bnext;
53 	int		loops;
54 };
55 
56 typedef struct hammer2_fiterate hammer2_fiterate_t;
57 
58 static int hammer2_freemap_try_alloc(hammer2_trans_t *trans,
59 			hammer2_chain_t **parentp, hammer2_blockref_t *bref,
60 			int radix, hammer2_fiterate_t *iter);
61 static void hammer2_freemap_init(hammer2_trans_t *trans, hammer2_mount_t *hmp,
62 			hammer2_key_t key, hammer2_chain_t *chain);
63 static int hammer2_bmap_alloc(hammer2_trans_t *trans, hammer2_mount_t *hmp,
64 			hammer2_bmap_data_t *bmap, uint16_t class,
65 			int n, int radix, hammer2_key_t *basep);
66 static int hammer2_freemap_iterate(hammer2_trans_t *trans,
67 			hammer2_chain_t **parentp, hammer2_chain_t **chainp,
68 			hammer2_fiterate_t *iter);
69 
70 static __inline
71 int
72 hammer2_freemapradix(int radix)
73 {
74 	return(radix);
75 }
76 
77 /*
78  * Calculate the device offset for the specified FREEMAP_NODE or FREEMAP_LEAF
79  * bref.  Return a combined media offset and physical size radix.  Freemap
80  * chains use fixed storage offsets in the 4MB reserved area at the
81  * beginning of each 2GB zone
82  *
83  * Rotate between four possibilities.  Theoretically this means we have three
84  * good freemaps in case of a crash which we can use as a base for the fixup
85  * scan at mount-time.
86  */
87 #define H2FMBASE(key, radix)	((key) & ~(((hammer2_off_t)1 << (radix)) - 1))
88 #define H2FMSHIFT(radix)	((hammer2_off_t)1 << (radix))
89 
90 static
91 int
92 hammer2_freemap_reserve(hammer2_trans_t *trans, hammer2_chain_t *chain,
93 			int radix)
94 {
95 	hammer2_blockref_t *bref = &chain->bref;
96 	hammer2_off_t off;
97 	int index;
98 	size_t bytes;
99 
100 	/*
101 	 * Physical allocation size -> radix.  Typically either 256 for
102 	 * a level 0 freemap leaf or 65536 for a level N freemap node.
103 	 *
104 	 * NOTE: A 256 byte bitmap represents 256 x 8 x 1024 = 2MB of storage.
105 	 *	 Do not use hammer2_allocsize() here as it has a min cap.
106 	 */
107 	bytes = 1 << radix;
108 
109 	/*
110 	 * Calculate block selection index 0..7 of current block.  If this
111 	 * is the first allocation of the block (verses a modification of an
112 	 * existing block), we use index 0, otherwise we use the next rotating
113 	 * index.
114 	 *
115 	 * NORMAL transactions use FREEMAP sections 0-5, while FREEBATCH
116 	 * transactions use sections 6 and 7.  FREEBATCH transactions are
117 	 * used by the batch freeing code to spool-off in-memory structures
118 	 * used to track the batch free scan.
119 	 */
120 	if (trans->flags & HAMMER2_TRANS_FREEBATCH) {
121 		if ((bref->data_off & ~HAMMER2_OFF_MASK_RADIX) == 0) {
122 			index = (HAMMER2_ZONE_FREEMAP_06 -
123 				 HAMMER2_ZONE_FREEMAP_00) / 4;
124 		} else {
125 			off = bref->data_off & ~HAMMER2_OFF_MASK_RADIX &
126 			      (((hammer2_off_t)1 <<
127 				HAMMER2_FREEMAP_LEVEL1_RADIX) - 1);
128 			off = off / HAMMER2_PBUFSIZE;
129 			KKASSERT(off >= HAMMER2_ZONE_FREEMAP_06 &&
130 				 off < HAMMER2_ZONE_FREEMAP_08);
131 			index = (int)(off - HAMMER2_ZONE_FREEMAP_00) / 4;
132 			KKASSERT(index >= 6 && index < 8);
133 			if (++index == 8)
134 				index = 6;
135 		}
136 	} else {
137 		if ((bref->data_off & ~HAMMER2_OFF_MASK_RADIX) == 0) {
138 			index = 0;
139 		} else {
140 			off = bref->data_off & ~HAMMER2_OFF_MASK_RADIX &
141 			      (((hammer2_off_t)1 <<
142 				HAMMER2_FREEMAP_LEVEL1_RADIX) - 1);
143 			off = off / HAMMER2_PBUFSIZE;
144 			KKASSERT(off >= HAMMER2_ZONE_FREEMAP_00 &&
145 				 off < HAMMER2_ZONE_FREEMAP_06);
146 			index = (int)(off - HAMMER2_ZONE_FREEMAP_00) / 4;
147 			KKASSERT(index >= 0 && index < 6);
148 			if (++index == 6)
149 				index = 0;
150 		}
151 	}
152 
153 	/*
154 	 * Calculate the block offset of the reserved block.  This will
155 	 * point into the 4MB reserved area at the base of the appropriate
156 	 * 2GB zone, once added to the FREEMAP_x selection above.
157 	 */
158 	switch(bref->keybits) {
159 	/* case HAMMER2_FREEMAP_LEVEL5_RADIX: not applicable */
160 	case HAMMER2_FREEMAP_LEVEL4_RADIX:	/* 2EB */
161 		KKASSERT(bref->type == HAMMER2_BREF_TYPE_FREEMAP_NODE);
162 		KKASSERT(bytes == HAMMER2_FREEMAP_LEVELN_PSIZE);
163 		off = H2FMBASE(bref->key, HAMMER2_FREEMAP_LEVEL4_RADIX) +
164 		      (index * 4 + HAMMER2_ZONE_FREEMAP_00 +
165 		       HAMMER2_ZONEFM_LEVEL4) * HAMMER2_PBUFSIZE;
166 		break;
167 	case HAMMER2_FREEMAP_LEVEL3_RADIX:	/* 2PB */
168 		KKASSERT(bref->type == HAMMER2_BREF_TYPE_FREEMAP_NODE);
169 		KKASSERT(bytes == HAMMER2_FREEMAP_LEVELN_PSIZE);
170 		off = H2FMBASE(bref->key, HAMMER2_FREEMAP_LEVEL3_RADIX) +
171 		      (index * 4 + HAMMER2_ZONE_FREEMAP_00 +
172 		       HAMMER2_ZONEFM_LEVEL3) * HAMMER2_PBUFSIZE;
173 		break;
174 	case HAMMER2_FREEMAP_LEVEL2_RADIX:	/* 2TB */
175 		KKASSERT(bref->type == HAMMER2_BREF_TYPE_FREEMAP_NODE);
176 		KKASSERT(bytes == HAMMER2_FREEMAP_LEVELN_PSIZE);
177 		off = H2FMBASE(bref->key, HAMMER2_FREEMAP_LEVEL2_RADIX) +
178 		      (index * 4 + HAMMER2_ZONE_FREEMAP_00 +
179 		       HAMMER2_ZONEFM_LEVEL2) * HAMMER2_PBUFSIZE;
180 		break;
181 	case HAMMER2_FREEMAP_LEVEL1_RADIX:	/* 2GB */
182 		KKASSERT(bref->type == HAMMER2_BREF_TYPE_FREEMAP_LEAF);
183 		KKASSERT(bytes == HAMMER2_FREEMAP_LEVELN_PSIZE);
184 		off = H2FMBASE(bref->key, HAMMER2_FREEMAP_LEVEL1_RADIX) +
185 		      (index * 4 + HAMMER2_ZONE_FREEMAP_00 +
186 		       HAMMER2_ZONEFM_LEVEL1) * HAMMER2_PBUFSIZE;
187 		break;
188 	default:
189 		panic("freemap: bad radix(2) %p %d\n", bref, bref->keybits);
190 		/* NOT REACHED */
191 		off = (hammer2_off_t)-1;
192 		break;
193 	}
194 	bref->data_off = off | radix;
195 #if FREEMAP_DEBUG
196 	kprintf("FREEMAP BLOCK TYPE %d %016jx/%d DATA_OFF=%016jx\n",
197 		bref->type, bref->key, bref->keybits, bref->data_off);
198 #endif
199 	return (0);
200 }
201 
202 /*
203  * Normal freemap allocator
204  *
205  * Use available hints to allocate space using the freemap.  Create missing
206  * freemap infrastructure on-the-fly as needed (including marking initial
207  * allocations using the iterator as allocated, instantiating new 2GB zones,
208  * and dealing with the end-of-media edge case).
209  *
210  * ip and bpref are only used as a heuristic to determine locality of
211  * reference.  bref->key may also be used heuristically.
212  */
213 int
214 hammer2_freemap_alloc(hammer2_trans_t *trans, hammer2_chain_t *chain,
215 		      size_t bytes)
216 {
217 	hammer2_mount_t *hmp = chain->hmp;
218 	hammer2_blockref_t *bref = &chain->bref;
219 	hammer2_chain_t *parent;
220 	int radix;
221 	int error;
222 	unsigned int hindex;
223 	hammer2_fiterate_t iter;
224 
225 	/*
226 	 * Validate the allocation size.  It must be a power of 2.
227 	 *
228 	 * For now require that the caller be aware of the minimum
229 	 * allocation (1K).
230 	 */
231 	radix = hammer2_getradix(bytes);
232 	KKASSERT((size_t)1 << radix == bytes);
233 
234 	if (bref->type == HAMMER2_BREF_TYPE_FREEMAP_NODE ||
235 	    bref->type == HAMMER2_BREF_TYPE_FREEMAP_LEAF) {
236 		/*
237 		 * Freemap blocks themselves are assigned from the reserve
238 		 * area, not allocated from the freemap.
239 		 */
240 		error = hammer2_freemap_reserve(trans, chain, radix);
241 		return error;
242 	}
243 
244 	KKASSERT(bytes >= HAMMER2_ALLOC_MIN && bytes <= HAMMER2_ALLOC_MAX);
245 
246 	if (trans->flags & (HAMMER2_TRANS_ISFLUSH | HAMMER2_TRANS_PREFLUSH))
247 		++trans->sync_xid;
248 
249 	/*
250 	 * Calculate the starting point for our allocation search.
251 	 *
252 	 * Each freemap leaf is dedicated to a specific freemap_radix.
253 	 * The freemap_radix can be more fine-grained than the device buffer
254 	 * radix which results in inodes being grouped together in their
255 	 * own segment, terminal-data (16K or less) and initial indirect
256 	 * block being grouped together, and then full-indirect and full-data
257 	 * blocks (64K) being grouped together.
258 	 *
259 	 * The single most important aspect of this is the inode grouping
260 	 * because that is what allows 'find' and 'ls' and other filesystem
261 	 * topology operations to run fast.
262 	 */
263 #if 0
264 	if (bref->data_off & ~HAMMER2_OFF_MASK_RADIX)
265 		bpref = bref->data_off & ~HAMMER2_OFF_MASK_RADIX;
266 	else if (trans->tmp_bpref)
267 		bpref = trans->tmp_bpref;
268 	else if (trans->tmp_ip)
269 		bpref = trans->tmp_ip->chain->bref.data_off;
270 	else
271 #endif
272 	/*
273 	 * Heuristic tracking index.  We would like one for each distinct
274 	 * bref type if possible.  heur_freemap[] has room for two classes
275 	 * for each type.  At a minimum we have to break-up our heuristic
276 	 * by device block sizes.
277 	 */
278 	hindex = hammer2_devblkradix(radix) - HAMMER2_MINIORADIX;
279 	KKASSERT(hindex < HAMMER2_FREEMAP_HEUR_NRADIX);
280 	hindex += bref->type * HAMMER2_FREEMAP_HEUR_NRADIX;
281 	hindex &= HAMMER2_FREEMAP_HEUR_TYPES * HAMMER2_FREEMAP_HEUR_NRADIX - 1;
282 	KKASSERT(hindex < HAMMER2_FREEMAP_HEUR);
283 
284 	iter.bpref = hmp->heur_freemap[hindex];
285 
286 	/*
287 	 * Make sure bpref is in-bounds.  It's ok if bpref covers a zone's
288 	 * reserved area, the try code will iterate past it.
289 	 */
290 	if (iter.bpref > hmp->voldata.volu_size)
291 		iter.bpref = hmp->voldata.volu_size - 1;
292 
293 	/*
294 	 * Iterate the freemap looking for free space before and after.
295 	 */
296 	parent = &hmp->fchain;
297 	hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
298 	error = EAGAIN;
299 	iter.bnext = iter.bpref;
300 	iter.loops = 0;
301 
302 	while (error == EAGAIN) {
303 		error = hammer2_freemap_try_alloc(trans, &parent, bref,
304 						  radix, &iter);
305 	}
306 	hmp->heur_freemap[hindex] = iter.bnext;
307 	hammer2_chain_unlock(parent);
308 
309 	if (trans->flags & (HAMMER2_TRANS_ISFLUSH | HAMMER2_TRANS_PREFLUSH))
310 		--trans->sync_xid;
311 
312 	return (error);
313 }
314 
315 static int
316 hammer2_freemap_try_alloc(hammer2_trans_t *trans, hammer2_chain_t **parentp,
317 			  hammer2_blockref_t *bref, int radix,
318 			  hammer2_fiterate_t *iter)
319 {
320 	hammer2_mount_t *hmp = (*parentp)->hmp;
321 	hammer2_off_t l0size;
322 	hammer2_off_t l1size;
323 	hammer2_off_t l1mask;
324 	hammer2_key_t key_dummy;
325 	hammer2_chain_t *chain;
326 	hammer2_off_t key;
327 	size_t bytes;
328 	uint16_t class;
329 	int error = 0;
330 	int cache_index = -1;
331 	int ddflag;
332 
333 
334 	/*
335 	 * Calculate the number of bytes being allocated, the number
336 	 * of contiguous bits of bitmap being allocated, and the bitmap
337 	 * mask.
338 	 *
339 	 * WARNING! cpu hardware may mask bits == 64 -> 0 and blow up the
340 	 *	    mask calculation.
341 	 */
342 	bytes = (size_t)1 << radix;
343 	class = (bref->type << 8) | hammer2_devblkradix(radix);
344 
345 	/*
346 	 * Lookup the level1 freemap chain, creating and initializing one
347 	 * if necessary.  Intermediate levels will be created automatically
348 	 * when necessary by hammer2_chain_create().
349 	 */
350 	key = H2FMBASE(iter->bnext, HAMMER2_FREEMAP_LEVEL1_RADIX);
351 	l0size = H2FMSHIFT(HAMMER2_FREEMAP_LEVEL0_RADIX);
352 	l1size = H2FMSHIFT(HAMMER2_FREEMAP_LEVEL1_RADIX);
353 	l1mask = l1size - 1;
354 
355 	chain = hammer2_chain_lookup(parentp, &key_dummy, key, key + l1mask,
356 				     &cache_index,
357 				     HAMMER2_LOOKUP_ALWAYS |
358 				     HAMMER2_LOOKUP_MATCHIND, &ddflag);
359 
360 	if (chain == NULL) {
361 		/*
362 		 * Create the missing leaf, be sure to initialize
363 		 * the auxillary freemap tracking information in
364 		 * the bref.check.freemap structure.
365 		 */
366 #if 0
367 		kprintf("freemap create L1 @ %016jx bpref %016jx\n",
368 			key, iter->bpref);
369 #endif
370 		error = hammer2_chain_create(trans, parentp, &chain, hmp->spmp,
371 				     key, HAMMER2_FREEMAP_LEVEL1_RADIX,
372 				     HAMMER2_BREF_TYPE_FREEMAP_LEAF,
373 				     HAMMER2_FREEMAP_LEVELN_PSIZE,
374 				     0);
375 		KKASSERT(error == 0);
376 		if (error == 0) {
377 			hammer2_chain_modify(trans, chain, 0);
378 			bzero(&chain->data->bmdata[0],
379 			      HAMMER2_FREEMAP_LEVELN_PSIZE);
380 			chain->bref.check.freemap.bigmask = (uint32_t)-1;
381 			chain->bref.check.freemap.avail = l1size;
382 			/* bref.methods should already be inherited */
383 
384 			hammer2_freemap_init(trans, hmp, key, chain);
385 		}
386 	} else if ((chain->bref.check.freemap.bigmask & (1 << radix)) == 0) {
387 		/*
388 		 * Already flagged as not having enough space
389 		 */
390 		error = ENOSPC;
391 	} else {
392 		/*
393 		 * Modify existing chain to setup for adjustment.
394 		 */
395 		hammer2_chain_modify(trans, chain, 0);
396 	}
397 
398 	/*
399 	 * Scan 2MB entries.
400 	 */
401 	if (error == 0) {
402 		hammer2_bmap_data_t *bmap;
403 		hammer2_key_t base_key;
404 		int count;
405 		int start;
406 		int n;
407 
408 		KKASSERT(chain->bref.type == HAMMER2_BREF_TYPE_FREEMAP_LEAF);
409 		start = (int)((iter->bnext - key) >>
410 			      HAMMER2_FREEMAP_LEVEL0_RADIX);
411 		KKASSERT(start >= 0 && start < HAMMER2_FREEMAP_COUNT);
412 		hammer2_chain_modify(trans, chain, 0);
413 
414 		error = ENOSPC;
415 		for (count = 0; count < HAMMER2_FREEMAP_COUNT; ++count) {
416 			if (start + count >= HAMMER2_FREEMAP_COUNT &&
417 			    start - count < 0) {
418 				break;
419 			}
420 			n = start + count;
421 			bmap = &chain->data->bmdata[n];
422 			if (n < HAMMER2_FREEMAP_COUNT && bmap->avail &&
423 			    (bmap->class == 0 || bmap->class == class)) {
424 				base_key = key + n * l0size;
425 				error = hammer2_bmap_alloc(trans, hmp, bmap,
426 							   class, n, radix,
427 							   &base_key);
428 				if (error != ENOSPC) {
429 					key = base_key;
430 					break;
431 				}
432 			}
433 			n = start - count;
434 			bmap = &chain->data->bmdata[n];
435 			if (n >= 0 && bmap->avail &&
436 			    (bmap->class == 0 || bmap->class == class)) {
437 				base_key = key + n * l0size;
438 				error = hammer2_bmap_alloc(trans, hmp, bmap,
439 							   class, n, radix,
440 							   &base_key);
441 				if (error != ENOSPC) {
442 					key = base_key;
443 					break;
444 				}
445 			}
446 		}
447 		if (error == ENOSPC)
448 			chain->bref.check.freemap.bigmask &= ~(1 << radix);
449 		/* XXX also scan down from original count */
450 	}
451 
452 	if (error == 0) {
453 		/*
454 		 * Assert validity.  Must be beyond the static allocator used
455 		 * by newfs_hammer2 (and thus also beyond the aux area),
456 		 * not go past the volume size, and must not be in the
457 		 * reserved segment area for a zone.
458 		 */
459 		KKASSERT(key >= hmp->voldata.allocator_beg &&
460 			 key + bytes <= hmp->voldata.volu_size);
461 		KKASSERT((key & HAMMER2_ZONE_MASK64) >= HAMMER2_ZONE_SEG);
462 		bref->data_off = key | radix;
463 
464 #if 0
465 		kprintf("alloc cp=%p %016jx %016jx using %016jx\n",
466 			chain,
467 			bref->key, bref->data_off, chain->bref.data_off);
468 #endif
469 	} else if (error == ENOSPC) {
470 		/*
471 		 * Return EAGAIN with next iteration in iter->bnext, or
472 		 * return ENOSPC if the allocation map has been exhausted.
473 		 */
474 		error = hammer2_freemap_iterate(trans, parentp, &chain, iter);
475 	}
476 
477 	/*
478 	 * Cleanup
479 	 */
480 	if (chain)
481 		hammer2_chain_unlock(chain);
482 	return (error);
483 }
484 
485 /*
486  * Allocate (1<<radix) bytes from the bmap whos base data offset is (*basep).
487  *
488  * If the linear iterator is mid-block we use it directly (the bitmap should
489  * already be marked allocated), otherwise we search for a block in the bitmap
490  * that fits the allocation request.
491  *
492  * A partial bitmap allocation sets the minimum bitmap granularity (16KB)
493  * to fully allocated and adjusts the linear allocator to allow the
494  * remaining space to be allocated.
495  */
496 static
497 int
498 hammer2_bmap_alloc(hammer2_trans_t *trans, hammer2_mount_t *hmp,
499 		   hammer2_bmap_data_t *bmap,
500 		   uint16_t class, int n, int radix, hammer2_key_t *basep)
501 {
502 	hammer2_io_t *dio;
503 	size_t size;
504 	size_t bsize;
505 	int bmradix;
506 	uint32_t bmmask;
507 	int offset;
508 	int error;
509 	int i;
510 	int j;
511 
512 	/*
513 	 * Take into account 2-bits per block when calculating bmradix.
514 	 */
515 	size = (size_t)1 << radix;
516 
517 	if (radix <= HAMMER2_FREEMAP_BLOCK_RADIX) {
518 		bmradix = 2;
519 		bsize = HAMMER2_FREEMAP_BLOCK_SIZE;
520 		/* (16K) 2 bits per allocation block */
521 	} else {
522 		bmradix = 2 << (radix - HAMMER2_FREEMAP_BLOCK_RADIX);
523 		bsize = size;
524 		/* (32K-256K) 4, 8, 16, 32 bits per allocation block */
525 	}
526 
527 	/*
528 	 * Use the linear iterator to pack small allocations, otherwise
529 	 * fall-back to finding a free 16KB chunk.  The linear iterator
530 	 * is only valid when *NOT* on a freemap chunking boundary (16KB).
531 	 * If it is the bitmap must be scanned.  It can become invalid
532 	 * once we pack to the boundary.  We adjust it after a bitmap
533 	 * allocation only for sub-16KB allocations (so the perfectly good
534 	 * previous value can still be used for fragments when 16KB+
535 	 * allocations are made).
536 	 *
537 	 * Beware of hardware artifacts when bmradix == 32 (intermediate
538 	 * result can wind up being '1' instead of '0' if hardware masks
539 	 * bit-count & 31).
540 	 *
541 	 * NOTE: j needs to be even in the j= calculation.  As an artifact
542 	 *	 of the /2 division, our bitmask has to clear bit 0.
543 	 *
544 	 * NOTE: TODO this can leave little unallocatable fragments lying
545 	 *	 around.
546 	 */
547 	if (((uint32_t)bmap->linear & HAMMER2_FREEMAP_BLOCK_MASK) + size <=
548 	    HAMMER2_FREEMAP_BLOCK_SIZE &&
549 	    (bmap->linear & HAMMER2_FREEMAP_BLOCK_MASK) &&
550 	    bmap->linear < HAMMER2_SEGSIZE) {
551 		KKASSERT(bmap->linear >= 0 &&
552 			 bmap->linear + size <= HAMMER2_SEGSIZE &&
553 			 (bmap->linear & (HAMMER2_ALLOC_MIN - 1)) == 0);
554 		offset = bmap->linear;
555 		i = offset / (HAMMER2_SEGSIZE / 8);
556 		j = (offset / (HAMMER2_FREEMAP_BLOCK_SIZE / 2)) & 30;
557 		bmmask = (bmradix == 32) ?
558 			 0xFFFFFFFFU : (1 << bmradix) - 1;
559 		bmmask <<= j;
560 		bmap->linear = offset + size;
561 	} else {
562 		for (i = 0; i < 8; ++i) {
563 			bmmask = (bmradix == 32) ?
564 				 0xFFFFFFFFU : (1 << bmradix) - 1;
565 			for (j = 0; j < 32; j += bmradix) {
566 				if ((bmap->bitmap[i] & bmmask) == 0)
567 					goto success;
568 				bmmask <<= bmradix;
569 			}
570 		}
571 		/*fragments might remain*/
572 		/*KKASSERT(bmap->avail == 0);*/
573 		return (ENOSPC);
574 success:
575 		offset = i * (HAMMER2_SEGSIZE / 8) +
576 			 (j * (HAMMER2_FREEMAP_BLOCK_SIZE / 2));
577 		if (size & HAMMER2_FREEMAP_BLOCK_MASK)
578 			bmap->linear = offset + size;
579 	}
580 
581 	KKASSERT(i >= 0 && i < 8);	/* 8 x 16 -> 128 x 16K -> 2MB */
582 
583 	/*
584 	 * Optimize the buffer cache to avoid unnecessary read-before-write
585 	 * operations.
586 	 *
587 	 * The device block size could be larger than the allocation size
588 	 * so the actual bitmap test is somewhat more involved.  We have
589 	 * to use a compatible buffer size for this operation.
590 	 */
591 	if ((bmap->bitmap[i] & bmmask) == 0 &&
592 	    hammer2_devblksize(size) != size) {
593 		size_t psize = hammer2_devblksize(size);
594 		hammer2_off_t pmask = (hammer2_off_t)psize - 1;
595 		int pbmradix = 2 << (hammer2_devblkradix(radix) -
596 				     HAMMER2_FREEMAP_BLOCK_RADIX);
597 		uint32_t pbmmask;
598 		int pradix = hammer2_getradix(psize);
599 
600 		pbmmask = (pbmradix == 32) ? 0xFFFFFFFFU : (1 << pbmradix) - 1;
601 		while ((pbmmask & bmmask) == 0)
602 			pbmmask <<= pbmradix;
603 
604 #if 0
605 		kprintf("%016jx mask %08x %08x %08x (%zd/%zd)\n",
606 			*basep + offset, bmap->bitmap[i],
607 			pbmmask, bmmask, size, psize);
608 #endif
609 
610 		if ((bmap->bitmap[i] & pbmmask) == 0) {
611 			error = hammer2_io_newq(hmp,
612 						(*basep + (offset & ~pmask)) |
613 						 pradix,
614 						psize, &dio);
615 			hammer2_io_bqrelse(&dio);
616 		}
617 	}
618 
619 #if 0
620 	/*
621 	 * When initializing a new inode segment also attempt to initialize
622 	 * an adjacent segment.  Be careful not to index beyond the array
623 	 * bounds.
624 	 *
625 	 * We do this to try to localize inode accesses to improve
626 	 * directory scan rates.  XXX doesn't improve scan rates.
627 	 */
628 	if (size == HAMMER2_INODE_BYTES) {
629 		if (n & 1) {
630 			if (bmap[-1].radix == 0 && bmap[-1].avail)
631 				bmap[-1].radix = radix;
632 		} else {
633 			if (bmap[1].radix == 0 && bmap[1].avail)
634 				bmap[1].radix = radix;
635 		}
636 	}
637 #endif
638 
639 	/*
640 	 * Adjust the linear iterator, set the radix if necessary (might as
641 	 * well just set it unconditionally), adjust *basep to return the
642 	 * allocated data offset.
643 	 */
644 	bmap->bitmap[i] |= bmmask;
645 	bmap->class = class;
646 	bmap->avail -= size;
647 	*basep += offset;
648 
649 	hammer2_voldata_lock(hmp);
650 	hammer2_voldata_modify(hmp);
651 	hmp->voldata.allocator_free -= size;  /* XXX */
652 	hammer2_voldata_unlock(hmp);
653 
654 	return(0);
655 }
656 
657 static
658 void
659 hammer2_freemap_init(hammer2_trans_t *trans, hammer2_mount_t *hmp,
660 		     hammer2_key_t key, hammer2_chain_t *chain)
661 {
662 	hammer2_off_t l1size;
663 	hammer2_off_t lokey;
664 	hammer2_off_t hikey;
665 	hammer2_bmap_data_t *bmap;
666 	int count;
667 
668 	l1size = H2FMSHIFT(HAMMER2_FREEMAP_LEVEL1_RADIX);
669 
670 	/*
671 	 * Calculate the portion of the 2GB map that should be initialized
672 	 * as free.  Portions below or after will be initialized as allocated.
673 	 * SEGMASK-align the areas so we don't have to worry about sub-scans
674 	 * or endianess when using memset.
675 	 *
676 	 * (1) Ensure that all statically allocated space from newfs_hammer2
677 	 *     is marked allocated.
678 	 *
679 	 * (2) Ensure that the reserved area is marked allocated (typically
680 	 *     the first 4MB of the 2GB area being represented).
681 	 *
682 	 * (3) Ensure that any trailing space at the end-of-volume is marked
683 	 *     allocated.
684 	 *
685 	 * WARNING! It is possible for lokey to be larger than hikey if the
686 	 *	    entire 2GB segment is within the static allocation.
687 	 */
688 	lokey = (hmp->voldata.allocator_beg + HAMMER2_SEGMASK64) &
689 		~HAMMER2_SEGMASK64;
690 
691 	if (lokey < H2FMBASE(key, HAMMER2_FREEMAP_LEVEL1_RADIX) +
692 		  HAMMER2_ZONE_SEG64) {
693 		lokey = H2FMBASE(key, HAMMER2_FREEMAP_LEVEL1_RADIX) +
694 			HAMMER2_ZONE_SEG64;
695 	}
696 
697 	hikey = key + H2FMSHIFT(HAMMER2_FREEMAP_LEVEL1_RADIX);
698 	if (hikey > hmp->voldata.volu_size) {
699 		hikey = hmp->voldata.volu_size & ~HAMMER2_SEGMASK64;
700 	}
701 
702 	chain->bref.check.freemap.avail =
703 		H2FMSHIFT(HAMMER2_FREEMAP_LEVEL1_RADIX);
704 	bmap = &chain->data->bmdata[0];
705 
706 	for (count = 0; count < HAMMER2_FREEMAP_COUNT; ++count) {
707 		if (key < lokey || key >= hikey) {
708 			memset(bmap->bitmap, -1,
709 			       sizeof(bmap->bitmap));
710 			bmap->avail = 0;
711 			bmap->linear = HAMMER2_SEGSIZE;
712 			chain->bref.check.freemap.avail -=
713 				H2FMSHIFT(HAMMER2_FREEMAP_LEVEL0_RADIX);
714 		} else {
715 			bmap->avail = H2FMSHIFT(HAMMER2_FREEMAP_LEVEL0_RADIX);
716 		}
717 		key += H2FMSHIFT(HAMMER2_FREEMAP_LEVEL0_RADIX);
718 		++bmap;
719 	}
720 }
721 
722 /*
723  * The current Level 1 freemap has been exhausted, iterate to the next
724  * one, return ENOSPC if no freemaps remain.
725  *
726  * XXX this should rotate back to the beginning to handle freed-up space
727  * XXX or use intermediate entries to locate free space. TODO
728  */
729 static int
730 hammer2_freemap_iterate(hammer2_trans_t *trans, hammer2_chain_t **parentp,
731 			hammer2_chain_t **chainp, hammer2_fiterate_t *iter)
732 {
733 	hammer2_mount_t *hmp = (*parentp)->hmp;
734 
735 	iter->bnext &= ~(H2FMSHIFT(HAMMER2_FREEMAP_LEVEL1_RADIX) - 1);
736 	iter->bnext += H2FMSHIFT(HAMMER2_FREEMAP_LEVEL1_RADIX);
737 	if (iter->bnext >= hmp->voldata.volu_size) {
738 		iter->bnext = 0;
739 		if (++iter->loops == 2)
740 			return (ENOSPC);
741 	}
742 	return(EAGAIN);
743 }
744 
745 /*
746  * Adjust the bit-pattern for data in the freemap bitmap according to
747  * (how).  This code is called from on-mount recovery to fixup (mark
748  * as allocated) blocks whos freemap upates might not have been committed
749  * in the last crash and is used by the bulk freemap scan to stage frees.
750  *
751  * XXX currently disabled when how == 0 (the normal real-time case).  At
752  * the moment we depend on the bulk freescan to actually free blocks.  It
753  * will still call this routine with a non-zero how to stage possible frees
754  * and to do the actual free.
755  */
756 void
757 hammer2_freemap_adjust(hammer2_trans_t *trans, hammer2_mount_t *hmp,
758 		       hammer2_blockref_t *bref, int how)
759 {
760 	hammer2_off_t data_off = bref->data_off;
761 	hammer2_chain_t *chain;
762 	hammer2_chain_t *parent;
763 	hammer2_bmap_data_t *bmap;
764 	hammer2_key_t key;
765 	hammer2_key_t key_dummy;
766 	hammer2_off_t l0size;
767 	hammer2_off_t l1size;
768 	hammer2_off_t l1mask;
769 	uint32_t *bitmap;
770 	const uint32_t bmmask00 = 0;
771 	uint32_t bmmask01;
772 	uint32_t bmmask10;
773 	uint32_t bmmask11;
774 	size_t bytes;
775 	uint16_t class;
776 	int radix;
777 	int start;
778 	int count;
779 	int modified = 0;
780 	int cache_index = -1;
781 	int error;
782 	int ddflag;
783 
784 	radix = (int)data_off & HAMMER2_OFF_MASK_RADIX;
785 	data_off &= ~HAMMER2_OFF_MASK_RADIX;
786 	KKASSERT(radix <= HAMMER2_RADIX_MAX);
787 
788 	bytes = (size_t)1 << radix;
789 	class = (bref->type << 8) | hammer2_devblkradix(radix);
790 
791 	/*
792 	 * We can't adjust thre freemap for data allocations made by
793 	 * newfs_hammer2.
794 	 */
795 	if (data_off < hmp->voldata.allocator_beg)
796 		return;
797 
798 	KKASSERT((data_off & HAMMER2_ZONE_MASK64) >= HAMMER2_ZONE_SEG);
799 
800 	/*
801 	 * Lookup the level1 freemap chain.  The chain must exist.
802 	 */
803 	key = H2FMBASE(data_off, HAMMER2_FREEMAP_LEVEL1_RADIX);
804 	l0size = H2FMSHIFT(HAMMER2_FREEMAP_LEVEL0_RADIX);
805 	l1size = H2FMSHIFT(HAMMER2_FREEMAP_LEVEL1_RADIX);
806 	l1mask = l1size - 1;
807 
808 	parent = &hmp->fchain;
809 	hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
810 
811 	chain = hammer2_chain_lookup(&parent, &key_dummy, key, key + l1mask,
812 				     &cache_index,
813 				     HAMMER2_LOOKUP_ALWAYS |
814 				     HAMMER2_LOOKUP_MATCHIND, &ddflag);
815 
816 	/*
817 	 * Stop early if we are trying to free something but no leaf exists.
818 	 */
819 	if (chain == NULL && how != HAMMER2_FREEMAP_DORECOVER) {
820 		kprintf("hammer2_freemap_adjust: %016jx: no chain\n",
821 			(intmax_t)bref->data_off);
822 		goto done;
823 	}
824 
825 	/*
826 	 * Create any missing leaf(s) if we are doing a recovery (marking
827 	 * the block(s) as being allocated instead of being freed).  Be sure
828 	 * to initialize the auxillary freemap tracking info in the
829 	 * bref.check.freemap structure.
830 	 */
831 	if (chain == NULL && how == HAMMER2_FREEMAP_DORECOVER) {
832 		error = hammer2_chain_create(trans, &parent, &chain, hmp->spmp,
833 				     key, HAMMER2_FREEMAP_LEVEL1_RADIX,
834 				     HAMMER2_BREF_TYPE_FREEMAP_LEAF,
835 				     HAMMER2_FREEMAP_LEVELN_PSIZE,
836 				     0);
837 
838 		if (hammer2_debug & 0x0040) {
839 			kprintf("fixup create chain %p %016jx:%d\n",
840 				chain, chain->bref.key, chain->bref.keybits);
841 		}
842 
843 		if (error == 0) {
844 			hammer2_chain_modify(trans, chain, 0);
845 			bzero(&chain->data->bmdata[0],
846 			      HAMMER2_FREEMAP_LEVELN_PSIZE);
847 			chain->bref.check.freemap.bigmask = (uint32_t)-1;
848 			chain->bref.check.freemap.avail = l1size;
849 			/* bref.methods should already be inherited */
850 
851 			hammer2_freemap_init(trans, hmp, key, chain);
852 		}
853 		/* XXX handle error */
854 	}
855 
856 #if FREEMAP_DEBUG
857 	kprintf("FREEMAP ADJUST TYPE %d %016jx/%d DATA_OFF=%016jx\n",
858 		chain->bref.type, chain->bref.key,
859 		chain->bref.keybits, chain->bref.data_off);
860 #endif
861 
862 	/*
863 	 * Calculate the bitmask (runs in 2-bit pairs).
864 	 */
865 	start = ((int)(data_off >> HAMMER2_FREEMAP_BLOCK_RADIX) & 15) * 2;
866 	bmmask01 = 1 << start;
867 	bmmask10 = 2 << start;
868 	bmmask11 = 3 << start;
869 
870 	/*
871 	 * Fixup the bitmap.  Partial blocks cannot be fully freed unless
872 	 * a bulk scan is able to roll them up.
873 	 */
874 	if (radix < HAMMER2_FREEMAP_BLOCK_RADIX) {
875 		count = 1;
876 		if (how == HAMMER2_FREEMAP_DOREALFREE)
877 			how = HAMMER2_FREEMAP_DOMAYFREE;
878 	} else {
879 		count = 1 << (radix - HAMMER2_FREEMAP_BLOCK_RADIX);
880 	}
881 
882 	/*
883 	 * [re]load the bmap and bitmap pointers.  Each bmap entry covers
884 	 * a 2MB swath.  The bmap itself (LEVEL1) covers 2GB.
885 	 *
886 	 * Be sure to reset the linear iterator to ensure that the adjustment
887 	 * is not ignored.
888 	 */
889 again:
890 	bmap = &chain->data->bmdata[(int)(data_off >> HAMMER2_SEGRADIX) &
891 				    (HAMMER2_FREEMAP_COUNT - 1)];
892 	bitmap = &bmap->bitmap[(int)(data_off >> (HAMMER2_SEGRADIX - 3)) & 7];
893 
894 	if (modified)
895 		bmap->linear = 0;
896 
897 	while (count) {
898 		KKASSERT(bmmask11);
899 		if (how == HAMMER2_FREEMAP_DORECOVER) {
900 			/*
901 			 * Recovery request, mark as allocated.
902 			 */
903 			if ((*bitmap & bmmask11) != bmmask11) {
904 				if (modified == 0) {
905 					hammer2_chain_modify(trans, chain, 0);
906 					modified = 1;
907 					goto again;
908 				}
909 				if ((*bitmap & bmmask11) == bmmask00)
910 					bmap->avail -= 1 << radix;
911 				if (bmap->class == 0)
912 					bmap->class = class;
913 				*bitmap |= bmmask11;
914 				if (hammer2_debug & 0x0040) {
915 					kprintf("hammer2_freemap_recover: "
916 						"fixup type=%02x "
917 						"block=%016jx/%zd\n",
918 						bref->type, data_off, bytes);
919 				}
920 			} else {
921 				/*
922 				kprintf("hammer2_freemap_recover:  good "
923 					"type=%02x block=%016jx/%zd\n",
924 					bref->type, data_off, bytes);
925 				*/
926 			}
927 		} else if ((*bitmap & bmmask11) == bmmask11) {
928 			/*
929 			 * Mayfree/Realfree request and bitmap is currently
930 			 * marked as being fully allocated.
931 			 */
932 			if (!modified) {
933 				hammer2_chain_modify(trans, chain, 0);
934 				modified = 1;
935 				goto again;
936 			}
937 			if (how == HAMMER2_FREEMAP_DOREALFREE)
938 				*bitmap &= ~bmmask11;
939 			else
940 				*bitmap = (*bitmap & ~bmmask11) | bmmask10;
941 		} else if ((*bitmap & bmmask11) == bmmask10) {
942 			/*
943 			 * Mayfree/Realfree request and bitmap is currently
944 			 * marked as being possibly freeable.
945 			 */
946 			if (how == HAMMER2_FREEMAP_DOREALFREE) {
947 				if (!modified) {
948 					hammer2_chain_modify(trans, chain, 0);
949 					modified = 1;
950 					goto again;
951 				}
952 				*bitmap &= ~bmmask11;
953 			}
954 		} else {
955 			/*
956 			 * 01 - Not implemented, currently illegal state
957 			 * 00 - Not allocated at all, illegal free.
958 			 */
959 			panic("hammer2_freemap_adjust: "
960 			      "Illegal state %08x(%08x)",
961 			      *bitmap, *bitmap & bmmask11);
962 		}
963 		--count;
964 		bmmask01 <<= 2;
965 		bmmask10 <<= 2;
966 		bmmask11 <<= 2;
967 	}
968 	if (how == HAMMER2_FREEMAP_DOREALFREE && modified) {
969 		bmap->avail += 1 << radix;
970 		KKASSERT(bmap->avail <= HAMMER2_SEGSIZE);
971 		if (bmap->avail == HAMMER2_SEGSIZE &&
972 		    bmap->bitmap[0] == 0 &&
973 		    bmap->bitmap[1] == 0 &&
974 		    bmap->bitmap[2] == 0 &&
975 		    bmap->bitmap[3] == 0 &&
976 		    bmap->bitmap[4] == 0 &&
977 		    bmap->bitmap[5] == 0 &&
978 		    bmap->bitmap[6] == 0 &&
979 		    bmap->bitmap[7] == 0) {
980 			key = H2FMBASE(data_off, HAMMER2_FREEMAP_LEVEL0_RADIX);
981 			kprintf("Freeseg %016jx\n", (intmax_t)key);
982 			bmap->class = 0;
983 		}
984 	}
985 
986 	/*
987 	 * chain->bref.check.freemap.bigmask (XXX)
988 	 *
989 	 * Setting bigmask is a hint to the allocation code that there might
990 	 * be something allocatable.  We also set this in recovery... it
991 	 * doesn't hurt and we might want to use the hint for other validation
992 	 * operations later on.
993 	 */
994 	if (modified)
995 		chain->bref.check.freemap.bigmask |= 1 << radix;
996 
997 	hammer2_chain_unlock(chain);
998 done:
999 	hammer2_chain_unlock(parent);
1000 }
1001 
1002 /*
1003  * Validate the freemap, in three stages.
1004  *
1005  * stage-1	ALLOCATED     -> POSSIBLY FREE
1006  *		POSSIBLY FREE -> POSSIBLY FREE (type corrected)
1007  *
1008  *	This transitions bitmap entries from ALLOCATED to POSSIBLY FREE.
1009  *	The POSSIBLY FREE state does not mean that a block is actually free
1010  *	and may be transitioned back to ALLOCATED in stage-2.
1011  *
1012  *	This is typically done during normal filesystem operations when
1013  *	something is deleted or a block is replaced.
1014  *
1015  *	This is done by bulkfree in-bulk after a memory-bounded meta-data
1016  *	scan to try to determine what might be freeable.
1017  *
1018  *	This can be done unconditionally through a freemap scan when the
1019  *	intention is to brute-force recover the proper state of the freemap.
1020  *
1021  * stage-2	POSSIBLY FREE -> ALLOCATED	(scan metadata topology)
1022  *
1023  *	This is done by bulkfree during a meta-data scan to ensure that
1024  *	all blocks still actually allocated by the filesystem are marked
1025  *	as such.
1026  *
1027  *	NOTE! Live filesystem transitions to POSSIBLY FREE can occur while
1028  *	      the bulkfree stage-2 and stage-3 is running.  The live filesystem
1029  *	      will use the alternative POSSIBLY FREE type (2) to prevent
1030  *	      stage-3 from improperly transitioning unvetted possibly-free
1031  *	      blocks to FREE.
1032  *
1033  * stage-3	POSSIBLY FREE (type 1) -> FREE	(scan freemap)
1034  *
1035  *	This is done by bulkfree to finalize POSSIBLY FREE states.
1036  *
1037  */
1038