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_INT(_vfs_zfs, OID_AUTO, abd_scatter_enabled, CTLFLAG_RWTUN,
157 &zfs_abd_scatter_enabled, 0, "Enable scattered ARC data buffers");
158 SYSCTL_ULONG(_vfs_zfs, OID_AUTO, abd_chunk_size, CTLFLAG_RDTUN,
159 &zfs_abd_chunk_size, 0, "The size of the chunks ABD allocates");
163 extern vmem_t *zio_alloc_arena;
166 kmem_cache_t *abd_chunk_cache;
167 static kstat_t *abd_ksp;
169 extern inline boolean_t abd_is_linear(abd_t *abd);
170 extern inline void abd_copy(abd_t *dabd, abd_t *sabd, size_t size);
171 extern inline void abd_copy_from_buf(abd_t *abd, const void *buf, size_t size);
172 extern inline void abd_copy_to_buf(void* buf, abd_t *abd, size_t size);
173 extern inline int abd_cmp_buf(abd_t *abd, const void *buf, size_t size);
174 extern inline void abd_zero(abd_t *abd, size_t size);
179 void *c = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE);
180 ASSERT3P(c, !=, NULL);
185 abd_free_chunk(void *c)
187 kmem_cache_free(abd_chunk_cache, c);
194 vmem_t *data_alloc_arena = NULL;
197 data_alloc_arena = zio_alloc_arena;
201 * Since ABD chunks do not appear in crash dumps, we pass KMC_NOTOUCH
202 * so that no allocator metadata is stored with the buffers.
204 abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0,
205 NULL, NULL, NULL, NULL, data_alloc_arena, KMC_NOTOUCH);
207 abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0,
208 NULL, NULL, NULL, NULL, 0, KMC_NOTOUCH | KMC_NODEBUG);
210 abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED,
211 sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
212 if (abd_ksp != NULL) {
213 abd_ksp->ks_data = &abd_stats;
214 kstat_install(abd_ksp);
221 if (abd_ksp != NULL) {
222 kstat_delete(abd_ksp);
226 kmem_cache_destroy(abd_chunk_cache);
227 abd_chunk_cache = NULL;
231 abd_chunkcnt_for_bytes(size_t size)
233 return (P2ROUNDUP(size, zfs_abd_chunk_size) / zfs_abd_chunk_size);
237 abd_scatter_chunkcnt(abd_t *abd)
239 ASSERT(!abd_is_linear(abd));
240 return (abd_chunkcnt_for_bytes(
241 abd->abd_u.abd_scatter.abd_offset + abd->abd_size));
245 abd_verify(abd_t *abd)
247 ASSERT3U(abd->abd_size, >, 0);
248 ASSERT3U(abd->abd_size, <=, SPA_MAXBLOCKSIZE);
249 ASSERT3U(abd->abd_flags, ==, abd->abd_flags & (ABD_FLAG_LINEAR |
250 ABD_FLAG_OWNER | ABD_FLAG_META));
251 IMPLY(abd->abd_parent != NULL, !(abd->abd_flags & ABD_FLAG_OWNER));
252 IMPLY(abd->abd_flags & ABD_FLAG_META, abd->abd_flags & ABD_FLAG_OWNER);
253 if (abd_is_linear(abd)) {
254 ASSERT3P(abd->abd_u.abd_linear.abd_buf, !=, NULL);
256 ASSERT3U(abd->abd_u.abd_scatter.abd_offset, <,
258 size_t n = abd_scatter_chunkcnt(abd);
259 for (int i = 0; i < n; i++) {
261 abd->abd_u.abd_scatter.abd_chunks[i], !=, NULL);
266 static inline abd_t *
267 abd_alloc_struct(size_t chunkcnt)
269 size_t size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]);
270 abd_t *abd = kmem_alloc(size, KM_PUSHPAGE);
271 ASSERT3P(abd, !=, NULL);
272 ABDSTAT_INCR(abdstat_struct_size, size);
278 abd_free_struct(abd_t *abd)
280 size_t chunkcnt = abd_is_linear(abd) ? 0 : abd_scatter_chunkcnt(abd);
281 int size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]);
282 kmem_free(abd, size);
283 ABDSTAT_INCR(abdstat_struct_size, -size);
287 * Allocate an ABD, along with its own underlying data buffers. Use this if you
288 * don't care whether the ABD is linear or not.
291 abd_alloc(size_t size, boolean_t is_metadata)
293 if (!zfs_abd_scatter_enabled || size <= zfs_abd_chunk_size)
294 return (abd_alloc_linear(size, is_metadata));
296 VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
298 size_t n = abd_chunkcnt_for_bytes(size);
299 abd_t *abd = abd_alloc_struct(n);
301 abd->abd_flags = ABD_FLAG_OWNER;
303 abd->abd_flags |= ABD_FLAG_META;
305 abd->abd_size = size;
306 abd->abd_parent = NULL;
307 zfs_refcount_create(&abd->abd_children);
309 abd->abd_u.abd_scatter.abd_offset = 0;
310 abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size;
312 for (int i = 0; i < n; i++) {
313 void *c = abd_alloc_chunk();
314 ASSERT3P(c, !=, NULL);
315 abd->abd_u.abd_scatter.abd_chunks[i] = c;
318 ABDSTAT_BUMP(abdstat_scatter_cnt);
319 ABDSTAT_INCR(abdstat_scatter_data_size, size);
320 ABDSTAT_INCR(abdstat_scatter_chunk_waste,
321 n * zfs_abd_chunk_size - size);
327 abd_free_scatter(abd_t *abd)
329 size_t n = abd_scatter_chunkcnt(abd);
330 for (int i = 0; i < n; i++) {
331 abd_free_chunk(abd->abd_u.abd_scatter.abd_chunks[i]);
334 zfs_refcount_destroy(&abd->abd_children);
335 ABDSTAT_BUMPDOWN(abdstat_scatter_cnt);
336 ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size);
337 ABDSTAT_INCR(abdstat_scatter_chunk_waste,
338 abd->abd_size - n * zfs_abd_chunk_size);
340 abd_free_struct(abd);
344 * Allocate an ABD that must be linear, along with its own underlying data
345 * buffer. Only use this when it would be very annoying to write your ABD
346 * consumer with a scattered ABD.
349 abd_alloc_linear(size_t size, boolean_t is_metadata)
351 abd_t *abd = abd_alloc_struct(0);
353 VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
355 abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER;
357 abd->abd_flags |= ABD_FLAG_META;
359 abd->abd_size = size;
360 abd->abd_parent = NULL;
361 zfs_refcount_create(&abd->abd_children);
364 abd->abd_u.abd_linear.abd_buf = zio_buf_alloc(size);
366 abd->abd_u.abd_linear.abd_buf = zio_data_buf_alloc(size);
369 ABDSTAT_BUMP(abdstat_linear_cnt);
370 ABDSTAT_INCR(abdstat_linear_data_size, size);
376 abd_free_linear(abd_t *abd)
378 if (abd->abd_flags & ABD_FLAG_META) {
379 zio_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size);
381 zio_data_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size);
384 zfs_refcount_destroy(&abd->abd_children);
385 ABDSTAT_BUMPDOWN(abdstat_linear_cnt);
386 ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
388 abd_free_struct(abd);
392 * Free an ABD. Only use this on ABDs allocated with abd_alloc() or
393 * abd_alloc_linear().
399 ASSERT3P(abd->abd_parent, ==, NULL);
400 ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
401 if (abd_is_linear(abd))
402 abd_free_linear(abd);
404 abd_free_scatter(abd);
408 * Allocate an ABD of the same format (same metadata flag, same scatterize
409 * setting) as another ABD.
412 abd_alloc_sametype(abd_t *sabd, size_t size)
414 boolean_t is_metadata = (sabd->abd_flags & ABD_FLAG_META) != 0;
415 if (abd_is_linear(sabd)) {
416 return (abd_alloc_linear(size, is_metadata));
418 return (abd_alloc(size, is_metadata));
423 * If we're going to use this ABD for doing I/O using the block layer, the
424 * consumer of the ABD data doesn't care if it's scattered or not, and we don't
425 * plan to store this ABD in memory for a long period of time, we should
426 * allocate the ABD type that requires the least data copying to do the I/O.
428 * Currently this is linear ABDs, however if ldi_strategy() can ever issue I/Os
429 * using a scatter/gather list we should switch to that and replace this call
430 * with vanilla abd_alloc().
433 abd_alloc_for_io(size_t size, boolean_t is_metadata)
435 return (abd_alloc_linear(size, is_metadata));
439 * Allocate a new ABD to point to offset off of sabd. It shares the underlying
440 * buffer data with sabd. Use abd_put() to free. sabd must not be freed while
441 * any derived ABDs exist.
444 abd_get_offset(abd_t *sabd, size_t off)
449 ASSERT3U(off, <=, sabd->abd_size);
451 if (abd_is_linear(sabd)) {
452 abd = abd_alloc_struct(0);
455 * Even if this buf is filesystem metadata, we only track that
456 * if we own the underlying data buffer, which is not true in
457 * this case. Therefore, we don't ever use ABD_FLAG_META here.
459 abd->abd_flags = ABD_FLAG_LINEAR;
461 abd->abd_u.abd_linear.abd_buf =
462 (char *)sabd->abd_u.abd_linear.abd_buf + off;
464 size_t new_offset = sabd->abd_u.abd_scatter.abd_offset + off;
465 size_t chunkcnt = abd_scatter_chunkcnt(sabd) -
466 (new_offset / zfs_abd_chunk_size);
468 abd = abd_alloc_struct(chunkcnt);
471 * Even if this buf is filesystem metadata, we only track that
472 * if we own the underlying data buffer, which is not true in
473 * this case. Therefore, we don't ever use ABD_FLAG_META here.
477 abd->abd_u.abd_scatter.abd_offset =
478 new_offset % zfs_abd_chunk_size;
479 abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size;
481 /* Copy the scatterlist starting at the correct offset */
482 (void) memcpy(&abd->abd_u.abd_scatter.abd_chunks,
483 &sabd->abd_u.abd_scatter.abd_chunks[new_offset /
485 chunkcnt * sizeof (void *));
488 abd->abd_size = sabd->abd_size - off;
489 abd->abd_parent = sabd;
490 zfs_refcount_create(&abd->abd_children);
491 (void) zfs_refcount_add_many(&sabd->abd_children, abd->abd_size, abd);
497 * Allocate a linear ABD structure for buf. You must free this with abd_put()
498 * since the resulting ABD doesn't own its own buffer.
501 abd_get_from_buf(void *buf, size_t size)
503 abd_t *abd = abd_alloc_struct(0);
505 VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
508 * Even if this buf is filesystem metadata, we only track that if we
509 * own the underlying data buffer, which is not true in this case.
510 * Therefore, we don't ever use ABD_FLAG_META here.
512 abd->abd_flags = ABD_FLAG_LINEAR;
513 abd->abd_size = size;
514 abd->abd_parent = NULL;
515 zfs_refcount_create(&abd->abd_children);
517 abd->abd_u.abd_linear.abd_buf = buf;
523 * Free an ABD allocated from abd_get_offset() or abd_get_from_buf(). Will not
524 * free the underlying scatterlist or buffer.
530 ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
532 if (abd->abd_parent != NULL) {
533 (void) zfs_refcount_remove_many(&abd->abd_parent->abd_children,
537 zfs_refcount_destroy(&abd->abd_children);
538 abd_free_struct(abd);
542 * Get the raw buffer associated with a linear ABD.
545 abd_to_buf(abd_t *abd)
547 ASSERT(abd_is_linear(abd));
549 return (abd->abd_u.abd_linear.abd_buf);
553 * Borrow a raw buffer from an ABD without copying the contents of the ABD
554 * into the buffer. If the ABD is scattered, this will allocate a raw buffer
555 * whose contents are undefined. To copy over the existing data in the ABD, use
556 * abd_borrow_buf_copy() instead.
559 abd_borrow_buf(abd_t *abd, size_t n)
563 ASSERT3U(abd->abd_size, >=, n);
564 if (abd_is_linear(abd)) {
565 buf = abd_to_buf(abd);
567 buf = zio_buf_alloc(n);
569 (void) zfs_refcount_add_many(&abd->abd_children, n, buf);
575 abd_borrow_buf_copy(abd_t *abd, size_t n)
577 void *buf = abd_borrow_buf(abd, n);
578 if (!abd_is_linear(abd)) {
579 abd_copy_to_buf(buf, abd, n);
585 * Return a borrowed raw buffer to an ABD. If the ABD is scattered, this will
586 * not change the contents of the ABD and will ASSERT that you didn't modify
587 * the buffer since it was borrowed. If you want any changes you made to buf to
588 * be copied back to abd, use abd_return_buf_copy() instead.
591 abd_return_buf(abd_t *abd, void *buf, size_t n)
594 ASSERT3U(abd->abd_size, >=, n);
595 if (abd_is_linear(abd)) {
596 ASSERT3P(buf, ==, abd_to_buf(abd));
598 ASSERT0(abd_cmp_buf(abd, buf, n));
599 zio_buf_free(buf, n);
601 (void) zfs_refcount_remove_many(&abd->abd_children, n, buf);
605 abd_return_buf_copy(abd_t *abd, void *buf, size_t n)
607 if (!abd_is_linear(abd)) {
608 abd_copy_from_buf(abd, buf, n);
610 abd_return_buf(abd, buf, n);
614 * Give this ABD ownership of the buffer that it's storing. Can only be used on
615 * linear ABDs which were allocated via abd_get_from_buf(), or ones allocated
616 * with abd_alloc_linear() which subsequently released ownership of their buf
617 * with abd_release_ownership_of_buf().
620 abd_take_ownership_of_buf(abd_t *abd, boolean_t is_metadata)
622 ASSERT(abd_is_linear(abd));
623 ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER));
626 abd->abd_flags |= ABD_FLAG_OWNER;
628 abd->abd_flags |= ABD_FLAG_META;
631 ABDSTAT_BUMP(abdstat_linear_cnt);
632 ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size);
636 abd_release_ownership_of_buf(abd_t *abd)
638 ASSERT(abd_is_linear(abd));
639 ASSERT(abd->abd_flags & ABD_FLAG_OWNER);
642 abd->abd_flags &= ~ABD_FLAG_OWNER;
643 /* Disable this flag since we no longer own the data buffer */
644 abd->abd_flags &= ~ABD_FLAG_META;
646 ABDSTAT_BUMPDOWN(abdstat_linear_cnt);
647 ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size);
651 abd_t *iter_abd; /* ABD being iterated through */
652 size_t iter_pos; /* position (relative to abd_offset) */
653 void *iter_mapaddr; /* addr corresponding to iter_pos */
654 size_t iter_mapsize; /* length of data valid at mapaddr */
658 abd_iter_scatter_chunk_offset(struct abd_iter *aiter)
660 ASSERT(!abd_is_linear(aiter->iter_abd));
661 return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset +
662 aiter->iter_pos) % zfs_abd_chunk_size);
666 abd_iter_scatter_chunk_index(struct abd_iter *aiter)
668 ASSERT(!abd_is_linear(aiter->iter_abd));
669 return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset +
670 aiter->iter_pos) / zfs_abd_chunk_size);
674 * Initialize the abd_iter.
677 abd_iter_init(struct abd_iter *aiter, abd_t *abd)
680 aiter->iter_abd = abd;
682 aiter->iter_mapaddr = NULL;
683 aiter->iter_mapsize = 0;
687 * Advance the iterator by a certain amount. Cannot be called when a chunk is
688 * in use. This can be safely called when the aiter has already exhausted, in
689 * which case this does nothing.
692 abd_iter_advance(struct abd_iter *aiter, size_t amount)
694 ASSERT3P(aiter->iter_mapaddr, ==, NULL);
695 ASSERT0(aiter->iter_mapsize);
697 /* There's nothing left to advance to, so do nothing */
698 if (aiter->iter_pos == aiter->iter_abd->abd_size)
701 aiter->iter_pos += amount;
705 * Map the current chunk into aiter. This can be safely called when the aiter
706 * has already exhausted, in which case this does nothing.
709 abd_iter_map(struct abd_iter *aiter)
714 ASSERT3P(aiter->iter_mapaddr, ==, NULL);
715 ASSERT0(aiter->iter_mapsize);
717 /* Panic if someone has changed zfs_abd_chunk_size */
718 IMPLY(!abd_is_linear(aiter->iter_abd), zfs_abd_chunk_size ==
719 aiter->iter_abd->abd_u.abd_scatter.abd_chunk_size);
721 /* There's nothing left to iterate over, so do nothing */
722 if (aiter->iter_pos == aiter->iter_abd->abd_size)
725 if (abd_is_linear(aiter->iter_abd)) {
726 offset = aiter->iter_pos;
727 aiter->iter_mapsize = aiter->iter_abd->abd_size - offset;
728 paddr = aiter->iter_abd->abd_u.abd_linear.abd_buf;
730 size_t index = abd_iter_scatter_chunk_index(aiter);
731 offset = abd_iter_scatter_chunk_offset(aiter);
732 aiter->iter_mapsize = zfs_abd_chunk_size - offset;
733 paddr = aiter->iter_abd->abd_u.abd_scatter.abd_chunks[index];
735 aiter->iter_mapaddr = (char *)paddr + offset;
739 * Unmap the current chunk from aiter. This can be safely called when the aiter
740 * has already exhausted, in which case this does nothing.
743 abd_iter_unmap(struct abd_iter *aiter)
745 /* There's nothing left to unmap, so do nothing */
746 if (aiter->iter_pos == aiter->iter_abd->abd_size)
749 ASSERT3P(aiter->iter_mapaddr, !=, NULL);
750 ASSERT3U(aiter->iter_mapsize, >, 0);
752 aiter->iter_mapaddr = NULL;
753 aiter->iter_mapsize = 0;
757 abd_iterate_func(abd_t *abd, size_t off, size_t size,
758 abd_iter_func_t *func, void *private)
761 struct abd_iter aiter;
764 ASSERT3U(off + size, <=, abd->abd_size);
766 abd_iter_init(&aiter, abd);
767 abd_iter_advance(&aiter, off);
770 abd_iter_map(&aiter);
772 size_t len = MIN(aiter.iter_mapsize, size);
775 ret = func(aiter.iter_mapaddr, len, private);
777 abd_iter_unmap(&aiter);
783 abd_iter_advance(&aiter, len);
794 abd_copy_to_buf_off_cb(void *buf, size_t size, void *private)
796 struct buf_arg *ba_ptr = private;
798 (void) memcpy(ba_ptr->arg_buf, buf, size);
799 ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
805 * Copy abd to buf. (off is the offset in abd.)
808 abd_copy_to_buf_off(void *buf, abd_t *abd, size_t off, size_t size)
810 struct buf_arg ba_ptr = { buf };
812 (void) abd_iterate_func(abd, off, size, abd_copy_to_buf_off_cb,
817 abd_cmp_buf_off_cb(void *buf, size_t size, void *private)
820 struct buf_arg *ba_ptr = private;
822 ret = memcmp(buf, ba_ptr->arg_buf, size);
823 ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
829 * Compare the contents of abd to buf. (off is the offset in abd.)
832 abd_cmp_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
834 struct buf_arg ba_ptr = { (void *) buf };
836 return (abd_iterate_func(abd, off, size, abd_cmp_buf_off_cb, &ba_ptr));
840 abd_copy_from_buf_off_cb(void *buf, size_t size, void *private)
842 struct buf_arg *ba_ptr = private;
844 (void) memcpy(buf, ba_ptr->arg_buf, size);
845 ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size;
851 * Copy from buf to abd. (off is the offset in abd.)
854 abd_copy_from_buf_off(abd_t *abd, const void *buf, size_t off, size_t size)
856 struct buf_arg ba_ptr = { (void *) buf };
858 (void) abd_iterate_func(abd, off, size, abd_copy_from_buf_off_cb,
864 abd_zero_off_cb(void *buf, size_t size, void *private)
866 (void) memset(buf, 0, size);
871 * Zero out the abd from a particular offset to the end.
874 abd_zero_off(abd_t *abd, size_t off, size_t size)
876 (void) abd_iterate_func(abd, off, size, abd_zero_off_cb, NULL);
880 * Iterate over two ABDs and call func incrementally on the two ABDs' data in
881 * equal-sized chunks (passed to func as raw buffers). func could be called many
882 * times during this iteration.
885 abd_iterate_func2(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff,
886 size_t size, abd_iter_func2_t *func, void *private)
889 struct abd_iter daiter, saiter;
894 ASSERT3U(doff + size, <=, dabd->abd_size);
895 ASSERT3U(soff + size, <=, sabd->abd_size);
897 abd_iter_init(&daiter, dabd);
898 abd_iter_init(&saiter, sabd);
899 abd_iter_advance(&daiter, doff);
900 abd_iter_advance(&saiter, soff);
903 abd_iter_map(&daiter);
904 abd_iter_map(&saiter);
906 size_t dlen = MIN(daiter.iter_mapsize, size);
907 size_t slen = MIN(saiter.iter_mapsize, size);
908 size_t len = MIN(dlen, slen);
909 ASSERT(dlen > 0 || slen > 0);
911 ret = func(daiter.iter_mapaddr, saiter.iter_mapaddr, len,
914 abd_iter_unmap(&saiter);
915 abd_iter_unmap(&daiter);
921 abd_iter_advance(&daiter, len);
922 abd_iter_advance(&saiter, len);
930 abd_copy_off_cb(void *dbuf, void *sbuf, size_t size, void *private)
932 (void) memcpy(dbuf, sbuf, size);
937 * Copy from sabd to dabd starting from soff and doff.
940 abd_copy_off(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size)
942 (void) abd_iterate_func2(dabd, sabd, doff, soff, size,
943 abd_copy_off_cb, NULL);
948 abd_cmp_cb(void *bufa, void *bufb, size_t size, void *private)
950 return (memcmp(bufa, bufb, size));
954 * Compares the first size bytes of two ABDs.
957 abd_cmp(abd_t *dabd, abd_t *sabd, size_t size)
959 return (abd_iterate_func2(dabd, sabd, 0, 0, size, abd_cmp_cb, NULL));