2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
13 * Copyright (c) 2014 by Chunwei Chen. All rights reserved.
14 * Copyright (c) 2016 by Delphix. All rights reserved.
18 * ARC buffer data (ABD).
20 * ABDs are an abstract data structure for the ARC which can use two
21 * different ways of storing the underlying data:
23 * (a) Linear buffer. In this case, all the data in the ABD is stored in one
24 * contiguous buffer in memory (from a zio_[data_]buf_* kmem cache).
26 * +-------------------+
29 * | abd_size = ... | +--------------------------------+
30 * | abd_buf ------------->| raw buffer of size abd_size |
31 * +-------------------+ +--------------------------------+
34 * (b) Scattered buffer. In this case, the data in the ABD is split into
35 * equal-sized chunks (from the abd_chunk_cache kmem_cache), with pointers
36 * to the chunks recorded in an array at the end of the ABD structure.
38 * +-------------------+
42 * | abd_offset = 0 | +-----------+
43 * | abd_chunks[0] ----------------------------->| chunk 0 |
44 * | abd_chunks[1] ---------------------+ +-----------+
45 * | ... | | +-----------+
46 * | abd_chunks[N-1] ---------+ +------->| chunk 1 |
47 * +-------------------+ | +-----------+
50 * +----------------->| chunk N-1 |
53 * Using a large proportion of scattered ABDs decreases ARC fragmentation since
54 * when we are at the limit of allocatable space, using equal-size chunks will
55 * allow us to quickly reclaim enough space for a new large allocation (assuming
56 * it is also scattered).
58 * In addition to directly allocating a linear or scattered ABD, it is also
59 * possible to create an ABD by requesting the "sub-ABD" starting at an offset
60 * within an existing ABD. In linear buffers this is simple (set abd_buf of
61 * the new ABD to the starting point within the original raw buffer), but
62 * scattered ABDs are a little more complex. The new ABD makes a copy of the
63 * relevant abd_chunks pointers (but not the underlying data). However, to
64 * provide arbitrary rather than only chunk-aligned starting offsets, it also
65 * tracks an abd_offset field which represents the starting point of the data
66 * within the first chunk in abd_chunks. For both linear and scattered ABDs,
67 * creating an offset ABD marks the original ABD as the offset's parent, and the
68 * original ABD's abd_children refcount is incremented. This data allows us to
69 * ensure the root ABD isn't deleted before its children.
71 * Most consumers should never need to know what type of ABD they're using --
72 * the ABD public API ensures that it's possible to transparently switch from
73 * using a linear ABD to a scattered one when doing so would be beneficial.
75 * If you need to use the data within an ABD directly, if you know it's linear
76 * (because you allocated it) you can use abd_to_buf() to access the underlying
77 * raw buffer. Otherwise, you should use one of the abd_borrow_buf* functions
78 * which will allocate a raw buffer if necessary. Use the abd_return_buf*
79 * functions to return any raw buffers that are no longer necessary when you're
82 * There are a variety of ABD APIs that implement basic buffer operations:
83 * compare, copy, read, write, and fill with zeroes. If you need a custom
84 * function which progressively accesses the whole ABD, use the abd_iterate_*
89 #include <sys/param.h>
91 #include <sys/zfs_context.h>
92 #include <sys/zfs_znode.h>
94 typedef struct abd_stats {
95 kstat_named_t abdstat_struct_size;
96 kstat_named_t abdstat_scatter_cnt;
97 kstat_named_t abdstat_scatter_data_size;
98 kstat_named_t abdstat_scatter_chunk_waste;
99 kstat_named_t abdstat_linear_cnt;
100 kstat_named_t abdstat_linear_data_size;
103 static abd_stats_t abd_stats = {
104 /* Amount of memory occupied by all of the abd_t struct allocations */
105 { "struct_size", KSTAT_DATA_UINT64 },
107 * The number of scatter ABDs which are currently allocated, excluding
108 * ABDs which don't own their data (for instance the ones which were
109 * allocated through abd_get_offset()).
111 { "scatter_cnt", KSTAT_DATA_UINT64 },
112 /* Amount of data stored in all scatter ABDs tracked by scatter_cnt */
113 { "scatter_data_size", KSTAT_DATA_UINT64 },
115 * The amount of space wasted at the end of the last chunk across all
116 * scatter ABDs tracked by scatter_cnt.
118 { "scatter_chunk_waste", KSTAT_DATA_UINT64 },
120 * The number of linear ABDs which are currently allocated, excluding
121 * ABDs which don't own their data (for instance the ones which were
122 * allocated through abd_get_offset() and abd_get_from_buf()). If an
123 * ABD takes ownership of its buf then it will become tracked.
125 { "linear_cnt", KSTAT_DATA_UINT64 },
126 /* Amount of data stored in all linear ABDs tracked by linear_cnt */
127 { "linear_data_size", KSTAT_DATA_UINT64 },
130 #define ABDSTAT(stat) (abd_stats.stat.value.ui64)
131 #define ABDSTAT_INCR(stat, val) \
132 atomic_add_64(&abd_stats.stat.value.ui64, (val))
133 #define ABDSTAT_BUMP(stat) ABDSTAT_INCR(stat, 1)
134 #define ABDSTAT_BUMPDOWN(stat) ABDSTAT_INCR(stat, -1)
137 * It is possible to make all future ABDs be linear by setting this to B_FALSE.
138 * Otherwise, ABDs are allocated scattered by default unless the caller uses
139 * abd_alloc_linear().
141 boolean_t zfs_abd_scatter_enabled = B_TRUE;
144 * The size of the chunks ABD allocates. Because the sizes allocated from the
145 * kmem_cache can't change, this tunable can only be modified at boot. Changing
146 * it at runtime would cause ABD iteration to work incorrectly for ABDs which
147 * were allocated with the old size, so a safeguard has been put in place which
148 * will cause the machine to panic if you change it and try to access the data
149 * within a scattered ABD.
151 size_t zfs_abd_chunk_size = 4096;
153 #if defined(__FreeBSD__) && defined(_KERNEL)
154 SYSCTL_DECL(_vfs_zfs);
156 SYSCTL_ULONG(_vfs_zfs, OID_AUTO, abd_chunk_size, CTLFLAG_RDTUN,
157 &zfs_abd_chunk_size, 0, "The size of the chunks ABD allocates");
161 extern vmem_t *zio_alloc_arena;
164 kmem_cache_t *abd_chunk_cache;
165 static kstat_t *abd_ksp;
167 extern inline boolean_t abd_is_linear(abd_t *abd);
168 extern inline void abd_copy(abd_t *dabd, abd_t *sabd, size_t size);
169 extern inline void abd_copy_from_buf(abd_t *abd, const void *buf, size_t size);
170 extern inline void abd_copy_to_buf(void* buf, abd_t *abd, size_t size);
171 extern inline int abd_cmp_buf(abd_t *abd, const void *buf, size_t size);
172 extern inline void abd_zero(abd_t *abd, size_t size);
177 void *c = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE);
178 ASSERT3P(c, !=, NULL);
183 abd_free_chunk(void *c)
185 kmem_cache_free(abd_chunk_cache, c);
192 vmem_t *data_alloc_arena = NULL;
195 data_alloc_arena = zio_alloc_arena;
199 * Since ABD chunks do not appear in crash dumps, we pass KMC_NOTOUCH
200 * so that no allocator metadata is stored with the buffers.
202 abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0,
203 NULL, NULL, NULL, NULL, data_alloc_arena, KMC_NOTOUCH);
205 abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0,
206 NULL, NULL, NULL, NULL, 0, KMC_NOTOUCH | KMC_NODEBUG);
208 abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED,
209 sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
210 if (abd_ksp != NULL) {
211 abd_ksp->ks_data = &abd_stats;
212 kstat_install(abd_ksp);
219 if (abd_ksp != NULL) {
220 kstat_delete(abd_ksp);
224 kmem_cache_destroy(abd_chunk_cache);
225 abd_chunk_cache = NULL;
229 abd_chunkcnt_for_bytes(size_t size)
231 return (P2ROUNDUP(size, zfs_abd_chunk_size) / zfs_abd_chunk_size);
235 abd_scatter_chunkcnt(abd_t *abd)
237 ASSERT(!abd_is_linear(abd));
238 return (abd_chunkcnt_for_bytes(
239 abd->abd_u.abd_scatter.abd_offset + abd->abd_size));
243 abd_verify(abd_t *abd)
245 ASSERT3U(abd->abd_size, >, 0);
246 ASSERT3U(abd->abd_size, <=, SPA_MAXBLOCKSIZE);
247 ASSERT3U(abd->abd_flags, ==, abd->abd_flags & (ABD_FLAG_LINEAR |
248 ABD_FLAG_OWNER | ABD_FLAG_META));
249 IMPLY(abd->abd_parent != NULL, !(abd->abd_flags & ABD_FLAG_OWNER));
250 IMPLY(abd->abd_flags & ABD_FLAG_META, abd->abd_flags & ABD_FLAG_OWNER);
251 if (abd_is_linear(abd)) {
252 ASSERT3P(abd->abd_u.abd_linear.abd_buf, !=, NULL);
254 ASSERT3U(abd->abd_u.abd_scatter.abd_offset, <,
256 size_t n = abd_scatter_chunkcnt(abd);
257 for (int i = 0; i < n; i++) {
259 abd->abd_u.abd_scatter.abd_chunks[i], !=, NULL);
264 static inline abd_t *
265 abd_alloc_struct(size_t chunkcnt)
267 size_t size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]);
268 abd_t *abd = kmem_alloc(size, KM_PUSHPAGE);
269 ASSERT3P(abd, !=, NULL);
270 ABDSTAT_INCR(abdstat_struct_size, size);
276 abd_free_struct(abd_t *abd)
278 size_t chunkcnt = abd_is_linear(abd) ? 0 : abd_scatter_chunkcnt(abd);
279 int size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]);
280 kmem_free(abd, size);
281 ABDSTAT_INCR(abdstat_struct_size, -size);
285 * Allocate an ABD, along with its own underlying data buffers. Use this if you
286 * don't care whether the ABD is linear or not.
289 abd_alloc(size_t size, boolean_t is_metadata)
291 if (!zfs_abd_scatter_enabled)
292 return (abd_alloc_linear(size, is_metadata));
294 VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
296 size_t n = abd_chunkcnt_for_bytes(size);
297 abd_t *abd = abd_alloc_struct(n);
299 abd->abd_flags = ABD_FLAG_OWNER;
301 abd->abd_flags |= ABD_FLAG_META;
303 abd->abd_size = size;
304 abd->abd_parent = NULL;
305 refcount_create(&abd->abd_children);
307 abd->abd_u.abd_scatter.abd_offset = 0;
308 abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size;
310 for (int i = 0; i < n; i++) {
311 void *c = abd_alloc_chunk();
312 ASSERT3P(c, !=, NULL);
313 abd->abd_u.abd_scatter.abd_chunks[i] = c;
316 ABDSTAT_BUMP(abdstat_scatter_cnt);
317 ABDSTAT_INCR(abdstat_scatter_data_size, size);
318 ABDSTAT_INCR(abdstat_scatter_chunk_waste,
319 n * zfs_abd_chunk_size - size);
325 abd_free_scatter(abd_t *abd)
327 size_t n = abd_scatter_chunkcnt(abd);
328 for (int i = 0; i < n; i++) {
329 abd_free_chunk(abd->abd_u.abd_scatter.abd_chunks[i]);
332 refcount_destroy(&abd->abd_children);
333 ABDSTAT_BUMPDOWN(abdstat_scatter_cnt);
334 ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size);
335 ABDSTAT_INCR(abdstat_scatter_chunk_waste,
336 abd->abd_size - n * zfs_abd_chunk_size);
338 abd_free_struct(abd);
342 * Allocate an ABD that must be linear, along with its own underlying data
343 * buffer. Only use this when it would be very annoying to write your ABD
344 * consumer with a scattered ABD.
347 abd_alloc_linear(size_t size, boolean_t is_metadata)
349 abd_t *abd = abd_alloc_struct(0);
351 VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
353 abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER;
355 abd->abd_flags |= ABD_FLAG_META;
357 abd->abd_size = size;
358 abd->abd_parent = NULL;
359 refcount_create(&abd->abd_children);
362 abd->abd_u.abd_linear.abd_buf = zio_buf_alloc(size);
364 abd->abd_u.abd_linear.abd_buf = zio_data_buf_alloc(size);
367 ABDSTAT_BUMP(abdstat_linear_cnt);
368 ABDSTAT_INCR(abdstat_linear_data_size, size);
374 abd_free_linear(abd_t *abd)
376 if (abd->abd_flags & ABD_FLAG_META) {
377 zio_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size);
379 zio_data_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size);
382 refcount_destroy(&abd->abd_children);
383 ABDSTAT_BUMPDOWN(abdstat_linear_cnt);
384 ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
386 abd_free_struct(abd);
390 * Free an ABD. Only use this on ABDs allocated with abd_alloc() or
391 * abd_alloc_linear().
397 ASSERT3P(abd->abd_parent, ==, NULL);
398 ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
399 if (abd_is_linear(abd))
400 abd_free_linear(abd);
402 abd_free_scatter(abd);
406 * Allocate an ABD of the same format (same metadata flag, same scatterize
407 * setting) as another ABD.
410 abd_alloc_sametype(abd_t *sabd, size_t size)
412 boolean_t is_metadata = (sabd->abd_flags & ABD_FLAG_META) != 0;
413 if (abd_is_linear(sabd)) {
414 return (abd_alloc_linear(size, is_metadata));
416 return (abd_alloc(size, is_metadata));
421 * If we're going to use this ABD for doing I/O using the block layer, the
422 * consumer of the ABD data doesn't care if it's scattered or not, and we don't
423 * plan to store this ABD in memory for a long period of time, we should
424 * allocate the ABD type that requires the least data copying to do the I/O.
426 * Currently this is linear ABDs, however if ldi_strategy() can ever issue I/Os
427 * using a scatter/gather list we should switch to that and replace this call
428 * with vanilla abd_alloc().
431 abd_alloc_for_io(size_t size, boolean_t is_metadata)
433 return (abd_alloc_linear(size, is_metadata));
437 * Allocate a new ABD to point to offset off of sabd. It shares the underlying
438 * buffer data with sabd. Use abd_put() to free. sabd must not be freed while
439 * any derived ABDs exist.
442 abd_get_offset(abd_t *sabd, size_t off)
447 ASSERT3U(off, <=, sabd->abd_size);
449 if (abd_is_linear(sabd)) {
450 abd = abd_alloc_struct(0);
453 * Even if this buf is filesystem metadata, we only track that
454 * if we own the underlying data buffer, which is not true in
455 * this case. Therefore, we don't ever use ABD_FLAG_META here.
457 abd->abd_flags = ABD_FLAG_LINEAR;
459 abd->abd_u.abd_linear.abd_buf =
460 (char *)sabd->abd_u.abd_linear.abd_buf + off;
462 size_t new_offset = sabd->abd_u.abd_scatter.abd_offset + off;
463 size_t chunkcnt = abd_scatter_chunkcnt(sabd) -
464 (new_offset / zfs_abd_chunk_size);
466 abd = abd_alloc_struct(chunkcnt);
469 * Even if this buf is filesystem metadata, we only track that
470 * if we own the underlying data buffer, which is not true in
471 * this case. Therefore, we don't ever use ABD_FLAG_META here.
475 abd->abd_u.abd_scatter.abd_offset =
476 new_offset % zfs_abd_chunk_size;
477 abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size;
479 /* Copy the scatterlist starting at the correct offset */
480 (void) memcpy(&abd->abd_u.abd_scatter.abd_chunks,
481 &sabd->abd_u.abd_scatter.abd_chunks[new_offset /
483 chunkcnt * sizeof (void *));
486 abd->abd_size = sabd->abd_size - off;
487 abd->abd_parent = sabd;
488 refcount_create(&abd->abd_children);
489 (void) refcount_add_many(&sabd->abd_children, abd->abd_size, abd);
495 * Allocate a linear ABD structure for buf. You must free this with abd_put()
496 * since the resulting ABD doesn't own its own buffer.
499 abd_get_from_buf(void *buf, size_t size)
501 abd_t *abd = abd_alloc_struct(0);
503 VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
506 * Even if this buf is filesystem metadata, we only track that if we
507 * own the underlying data buffer, which is not true in this case.
508 * Therefore, we don't ever use ABD_FLAG_META here.
510 abd->abd_flags = ABD_FLAG_LINEAR;
511 abd->abd_size = size;
512 abd->abd_parent = NULL;
513 refcount_create(&abd->abd_children);
515 abd->abd_u.abd_linear.abd_buf = buf;
521 * Free an ABD allocated from abd_get_offset() or abd_get_from_buf(). Will not
522 * free the underlying scatterlist or buffer.
528 ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
530 if (abd->abd_parent != NULL) {
531 (void) refcount_remove_many(&abd->abd_parent->abd_children,
535 refcount_destroy(&abd->abd_children);
536 abd_free_struct(abd);
540 * Get the raw buffer associated with a linear ABD.
543 abd_to_buf(abd_t *abd)
545 ASSERT(abd_is_linear(abd));
547 return (abd->abd_u.abd_linear.abd_buf);
551 * Borrow a raw buffer from an ABD without copying the contents of the ABD
552 * into the buffer. If the ABD is scattered, this will allocate a raw buffer
553 * whose contents are undefined. To copy over the existing data in the ABD, use
554 * abd_borrow_buf_copy() instead.
557 abd_borrow_buf(abd_t *abd, size_t n)
561 ASSERT3U(abd->abd_size, >=, n);
562 if (abd_is_linear(abd)) {
563 buf = abd_to_buf(abd);
565 buf = zio_buf_alloc(n);
567 (void) refcount_add_many(&abd->abd_children, n, buf);
573 abd_borrow_buf_copy(abd_t *abd, size_t n)
575 void *buf = abd_borrow_buf(abd, n);
576 if (!abd_is_linear(abd)) {
577 abd_copy_to_buf(buf, abd, n);
583 * Return a borrowed raw buffer to an ABD. If the ABD is scattered, this will
584 * not change the contents of the ABD and will ASSERT that you didn't modify
585 * the buffer since it was borrowed. If you want any changes you made to buf to
586 * be copied back to abd, use abd_return_buf_copy() instead.
589 abd_return_buf(abd_t *abd, void *buf, size_t n)
592 ASSERT3U(abd->abd_size, >=, n);
593 if (abd_is_linear(abd)) {
594 ASSERT3P(buf, ==, abd_to_buf(abd));
596 ASSERT0(abd_cmp_buf(abd, buf, n));
597 zio_buf_free(buf, n);
599 (void) refcount_remove_many(&abd->abd_children, n, buf);
603 abd_return_buf_copy(abd_t *abd, void *buf, size_t n)
605 if (!abd_is_linear(abd)) {
606 abd_copy_from_buf(abd, buf, n);
608 abd_return_buf(abd, buf, n);
612 * Give this ABD ownership of the buffer that it's storing. Can only be used on
613 * linear ABDs which were allocated via abd_get_from_buf(), or ones allocated
614 * with abd_alloc_linear() which subsequently released ownership of their buf
615 * with abd_release_ownership_of_buf().
618 abd_take_ownership_of_buf(abd_t *abd, boolean_t is_metadata)
620 ASSERT(abd_is_linear(abd));
621 ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
624 abd->abd_flags |= ABD_FLAG_OWNER;
626 abd->abd_flags |= ABD_FLAG_META;
629 ABDSTAT_BUMP(abdstat_linear_cnt);
630 ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size);
634 abd_release_ownership_of_buf(abd_t *abd)
636 ASSERT(abd_is_linear(abd));
637 ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
640 abd->abd_flags &= ~ABD_FLAG_OWNER;
641 /* Disable this flag since we no longer own the data buffer */
642 abd->abd_flags &= ~ABD_FLAG_META;
644 ABDSTAT_BUMPDOWN(abdstat_linear_cnt);
645 ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
649 abd_t *iter_abd; /* ABD being iterated through */
650 size_t iter_pos; /* position (relative to abd_offset) */
651 void *iter_mapaddr; /* addr corresponding to iter_pos */
652 size_t iter_mapsize; /* length of data valid at mapaddr */
656 abd_iter_scatter_chunk_offset(struct abd_iter *aiter)
658 ASSERT(!abd_is_linear(aiter->iter_abd));
659 return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset +
660 aiter->iter_pos) % zfs_abd_chunk_size);
664 abd_iter_scatter_chunk_index(struct abd_iter *aiter)
666 ASSERT(!abd_is_linear(aiter->iter_abd));
667 return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset +
668 aiter->iter_pos) / zfs_abd_chunk_size);
672 * Initialize the abd_iter.
675 abd_iter_init(struct abd_iter *aiter, abd_t *abd)
678 aiter->iter_abd = abd;
680 aiter->iter_mapaddr = NULL;
681 aiter->iter_mapsize = 0;
685 * Advance the iterator by a certain amount. Cannot be called when a chunk is
686 * in use. This can be safely called when the aiter has already exhausted, in
687 * which case this does nothing.
690 abd_iter_advance(struct abd_iter *aiter, size_t amount)
692 ASSERT3P(aiter->iter_mapaddr, ==, NULL);
693 ASSERT0(aiter->iter_mapsize);
695 /* There's nothing left to advance to, so do nothing */
696 if (aiter->iter_pos == aiter->iter_abd->abd_size)
699 aiter->iter_pos += amount;
703 * Map the current chunk into aiter. This can be safely called when the aiter
704 * has already exhausted, in which case this does nothing.
707 abd_iter_map(struct abd_iter *aiter)
712 ASSERT3P(aiter->iter_mapaddr, ==, NULL);
713 ASSERT0(aiter->iter_mapsize);
715 /* Panic if someone has changed zfs_abd_chunk_size */
716 IMPLY(!abd_is_linear(aiter->iter_abd), zfs_abd_chunk_size ==
717 aiter->iter_abd->abd_u.abd_scatter.abd_chunk_size);
719 /* There's nothing left to iterate over, so do nothing */
720 if (aiter->iter_pos == aiter->iter_abd->abd_size)
723 if (abd_is_linear(aiter->iter_abd)) {
724 offset = aiter->iter_pos;
725 aiter->iter_mapsize = aiter->iter_abd->abd_size - offset;
726 paddr = aiter->iter_abd->abd_u.abd_linear.abd_buf;
728 size_t index = abd_iter_scatter_chunk_index(aiter);
729 offset = abd_iter_scatter_chunk_offset(aiter);
730 aiter->iter_mapsize = zfs_abd_chunk_size - offset;
731 paddr = aiter->iter_abd->abd_u.abd_scatter.abd_chunks[index];
733 aiter->iter_mapaddr = (char *)paddr + offset;
737 * Unmap the current chunk from aiter. This can be safely called when the aiter
738 * has already exhausted, in which case this does nothing.
741 abd_iter_unmap(struct abd_iter *aiter)
743 /* There's nothing left to unmap, so do nothing */
744 if (aiter->iter_pos == aiter->iter_abd->abd_size)
747 ASSERT3P(aiter->iter_mapaddr, !=, NULL);
748 ASSERT3U(aiter->iter_mapsize, >, 0);
750 aiter->iter_mapaddr = NULL;
751 aiter->iter_mapsize = 0;
755 abd_iterate_func(abd_t *abd, size_t off, size_t size,
756 abd_iter_func_t *func, void *private)
759 struct abd_iter aiter;
762 ASSERT3U(off + size, <=, abd->abd_size);
764 abd_iter_init(&aiter, abd);
765 abd_iter_advance(&aiter, off);
768 abd_iter_map(&aiter);
770 size_t len = MIN(aiter.iter_mapsize, size);
773 ret = func(aiter.iter_mapaddr, len, private);
775 abd_iter_unmap(&aiter);
781 abd_iter_advance(&aiter, len);
792 abd_copy_to_buf_off_cb(void *buf, size_t size, void *private)
794 struct buf_arg *ba_ptr = private;
796 (void) memcpy(ba_ptr->arg_buf, buf, size);
797 ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
803 * Copy abd to buf. (off is the offset in abd.)
806 abd_copy_to_buf_off(void *buf, abd_t *abd, size_t off, size_t size)
808 struct buf_arg ba_ptr = { buf };
810 (void) abd_iterate_func(abd, off, size, abd_copy_to_buf_off_cb,
815 abd_cmp_buf_off_cb(void *buf, size_t size, void *private)
818 struct buf_arg *ba_ptr = private;
820 ret = memcmp(buf, ba_ptr->arg_buf, size);
821 ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
827 * Compare the contents of abd to buf. (off is the offset in abd.)
830 abd_cmp_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
832 struct buf_arg ba_ptr = { (void *) buf };
834 return (abd_iterate_func(abd, off, size, abd_cmp_buf_off_cb, &ba_ptr));
838 abd_copy_from_buf_off_cb(void *buf, size_t size, void *private)
840 struct buf_arg *ba_ptr = private;
842 (void) memcpy(buf, ba_ptr->arg_buf, size);
843 ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
849 * Copy from buf to abd. (off is the offset in abd.)
852 abd_copy_from_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
854 struct buf_arg ba_ptr = { (void *) buf };
856 (void) abd_iterate_func(abd, off, size, abd_copy_from_buf_off_cb,
862 abd_zero_off_cb(void *buf, size_t size, void *private)
864 (void) memset(buf, 0, size);
869 * Zero out the abd from a particular offset to the end.
872 abd_zero_off(abd_t *abd, size_t off, size_t size)
874 (void) abd_iterate_func(abd, off, size, abd_zero_off_cb, NULL);
878 * Iterate over two ABDs and call func incrementally on the two ABDs' data in
879 * equal-sized chunks (passed to func as raw buffers). func could be called many
880 * times during this iteration.
883 abd_iterate_func2(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff,
884 size_t size, abd_iter_func2_t *func, void *private)
887 struct abd_iter daiter, saiter;
892 ASSERT3U(doff + size, <=, dabd->abd_size);
893 ASSERT3U(soff + size, <=, sabd->abd_size);
895 abd_iter_init(&daiter, dabd);
896 abd_iter_init(&saiter, sabd);
897 abd_iter_advance(&daiter, doff);
898 abd_iter_advance(&saiter, soff);
901 abd_iter_map(&daiter);
902 abd_iter_map(&saiter);
904 size_t dlen = MIN(daiter.iter_mapsize, size);
905 size_t slen = MIN(saiter.iter_mapsize, size);
906 size_t len = MIN(dlen, slen);
907 ASSERT(dlen > 0 || slen > 0);
909 ret = func(daiter.iter_mapaddr, saiter.iter_mapaddr, len,
912 abd_iter_unmap(&saiter);
913 abd_iter_unmap(&daiter);
919 abd_iter_advance(&daiter, len);
920 abd_iter_advance(&saiter, len);
928 abd_copy_off_cb(void *dbuf, void *sbuf, size_t size, void *private)
930 (void) memcpy(dbuf, sbuf, size);
935 * Copy from sabd to dabd starting from soff and doff.
938 abd_copy_off(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size)
940 (void) abd_iterate_func2(dabd, sabd, doff, soff, size,
941 abd_copy_off_cb, NULL);
946 abd_cmp_cb(void *bufa, void *bufb, size_t size, void *private)
948 return (memcmp(bufa, bufb, size));
952 * Compares the first size bytes of two ABDs.
955 abd_cmp(abd_t *dabd, abd_t *sabd, size_t size)
957 return (abd_iterate_func2(dabd, sabd, 0, 0, size, abd_cmp_cb, NULL));