abd.c revision 324160
1318946Savg/* 2318946Savg * This file and its contents are supplied under the terms of the 3318946Savg * Common Development and Distribution License ("CDDL"), version 1.0. 4318946Savg * You may only use this file in accordance with the terms of version 5318946Savg * 1.0 of the CDDL. 6318946Savg * 7318946Savg * A full copy of the text of the CDDL should have accompanied this 8318946Savg * source. A copy of the CDDL is also available via the Internet at 9318946Savg * http://www.illumos.org/license/CDDL. 10318946Savg */ 11318946Savg 12318946Savg/* 13318946Savg * Copyright (c) 2014 by Chunwei Chen. All rights reserved. 14318946Savg * Copyright (c) 2016 by Delphix. All rights reserved. 15318946Savg */ 16318946Savg 17318946Savg/* 18318946Savg * ARC buffer data (ABD). 19318946Savg * 20318946Savg * ABDs are an abstract data structure for the ARC which can use two 21318946Savg * different ways of storing the underlying data: 22318946Savg * 23318946Savg * (a) Linear buffer. In this case, all the data in the ABD is stored in one 24318946Savg * contiguous buffer in memory (from a zio_[data_]buf_* kmem cache). 25318946Savg * 26318946Savg * +-------------------+ 27318946Savg * | ABD (linear) | 28318946Savg * | abd_flags = ... | 29318946Savg * | abd_size = ... | +--------------------------------+ 30318946Savg * | abd_buf ------------->| raw buffer of size abd_size | 31318946Savg * +-------------------+ +--------------------------------+ 32318946Savg * no abd_chunks 33318946Savg * 34318946Savg * (b) Scattered buffer. In this case, the data in the ABD is split into 35318946Savg * equal-sized chunks (from the abd_chunk_cache kmem_cache), with pointers 36318946Savg * to the chunks recorded in an array at the end of the ABD structure. 37318946Savg * 38318946Savg * +-------------------+ 39318946Savg * | ABD (scattered) | 40318946Savg * | abd_flags = ... | 41318946Savg * | abd_size = ... | 42318946Savg * | abd_offset = 0 | +-----------+ 43318946Savg * | abd_chunks[0] ----------------------------->| chunk 0 | 44318946Savg * | abd_chunks[1] ---------------------+ +-----------+ 45318946Savg * | ... | | +-----------+ 46318946Savg * | abd_chunks[N-1] ---------+ +------->| chunk 1 | 47318946Savg * +-------------------+ | +-----------+ 48318946Savg * | ... 49318946Savg * | +-----------+ 50318946Savg * +----------------->| chunk N-1 | 51318946Savg * +-----------+ 52318946Savg * 53318946Savg * Using a large proportion of scattered ABDs decreases ARC fragmentation since 54318946Savg * when we are at the limit of allocatable space, using equal-size chunks will 55318946Savg * allow us to quickly reclaim enough space for a new large allocation (assuming 56318946Savg * it is also scattered). 57318946Savg * 58318946Savg * In addition to directly allocating a linear or scattered ABD, it is also 59318946Savg * possible to create an ABD by requesting the "sub-ABD" starting at an offset 60318946Savg * within an existing ABD. In linear buffers this is simple (set abd_buf of 61318946Savg * the new ABD to the starting point within the original raw buffer), but 62318946Savg * scattered ABDs are a little more complex. The new ABD makes a copy of the 63318946Savg * relevant abd_chunks pointers (but not the underlying data). However, to 64318946Savg * provide arbitrary rather than only chunk-aligned starting offsets, it also 65318946Savg * tracks an abd_offset field which represents the starting point of the data 66318946Savg * within the first chunk in abd_chunks. For both linear and scattered ABDs, 67318946Savg * creating an offset ABD marks the original ABD as the offset's parent, and the 68318946Savg * original ABD's abd_children refcount is incremented. This data allows us to 69318946Savg * ensure the root ABD isn't deleted before its children. 70318946Savg * 71318946Savg * Most consumers should never need to know what type of ABD they're using -- 72318946Savg * the ABD public API ensures that it's possible to transparently switch from 73318946Savg * using a linear ABD to a scattered one when doing so would be beneficial. 74318946Savg * 75318946Savg * If you need to use the data within an ABD directly, if you know it's linear 76318946Savg * (because you allocated it) you can use abd_to_buf() to access the underlying 77318946Savg * raw buffer. Otherwise, you should use one of the abd_borrow_buf* functions 78318946Savg * which will allocate a raw buffer if necessary. Use the abd_return_buf* 79318946Savg * functions to return any raw buffers that are no longer necessary when you're 80318946Savg * done using them. 81318946Savg * 82318946Savg * There are a variety of ABD APIs that implement basic buffer operations: 83318946Savg * compare, copy, read, write, and fill with zeroes. If you need a custom 84318946Savg * function which progressively accesses the whole ABD, use the abd_iterate_* 85318946Savg * functions. 86318946Savg */ 87318946Savg 88318946Savg#include <sys/abd.h> 89318946Savg#include <sys/param.h> 90318946Savg#include <sys/zio.h> 91318946Savg#include <sys/zfs_context.h> 92318946Savg#include <sys/zfs_znode.h> 93318946Savg 94318946Savgtypedef struct abd_stats { 95318946Savg kstat_named_t abdstat_struct_size; 96318946Savg kstat_named_t abdstat_scatter_cnt; 97318946Savg kstat_named_t abdstat_scatter_data_size; 98318946Savg kstat_named_t abdstat_scatter_chunk_waste; 99318946Savg kstat_named_t abdstat_linear_cnt; 100318946Savg kstat_named_t abdstat_linear_data_size; 101318946Savg} abd_stats_t; 102318946Savg 103318946Savgstatic abd_stats_t abd_stats = { 104318946Savg /* Amount of memory occupied by all of the abd_t struct allocations */ 105318946Savg { "struct_size", KSTAT_DATA_UINT64 }, 106318946Savg /* 107318946Savg * The number of scatter ABDs which are currently allocated, excluding 108318946Savg * ABDs which don't own their data (for instance the ones which were 109318946Savg * allocated through abd_get_offset()). 110318946Savg */ 111318946Savg { "scatter_cnt", KSTAT_DATA_UINT64 }, 112318946Savg /* Amount of data stored in all scatter ABDs tracked by scatter_cnt */ 113318946Savg { "scatter_data_size", KSTAT_DATA_UINT64 }, 114318946Savg /* 115318946Savg * The amount of space wasted at the end of the last chunk across all 116318946Savg * scatter ABDs tracked by scatter_cnt. 117318946Savg */ 118318946Savg { "scatter_chunk_waste", KSTAT_DATA_UINT64 }, 119318946Savg /* 120318946Savg * The number of linear ABDs which are currently allocated, excluding 121318946Savg * ABDs which don't own their data (for instance the ones which were 122318946Savg * allocated through abd_get_offset() and abd_get_from_buf()). If an 123318946Savg * ABD takes ownership of its buf then it will become tracked. 124318946Savg */ 125318946Savg { "linear_cnt", KSTAT_DATA_UINT64 }, 126318946Savg /* Amount of data stored in all linear ABDs tracked by linear_cnt */ 127318946Savg { "linear_data_size", KSTAT_DATA_UINT64 }, 128318946Savg}; 129318946Savg 130318946Savg#define ABDSTAT(stat) (abd_stats.stat.value.ui64) 131318946Savg#define ABDSTAT_INCR(stat, val) \ 132318946Savg atomic_add_64(&abd_stats.stat.value.ui64, (val)) 133318946Savg#define ABDSTAT_BUMP(stat) ABDSTAT_INCR(stat, 1) 134318946Savg#define ABDSTAT_BUMPDOWN(stat) ABDSTAT_INCR(stat, -1) 135318946Savg 136318946Savg/* 137318946Savg * It is possible to make all future ABDs be linear by setting this to B_FALSE. 138318946Savg * Otherwise, ABDs are allocated scattered by default unless the caller uses 139318946Savg * abd_alloc_linear(). 140318946Savg */ 141318946Savgboolean_t zfs_abd_scatter_enabled = B_TRUE; 142318946Savg 143318946Savg/* 144318946Savg * The size of the chunks ABD allocates. Because the sizes allocated from the 145318946Savg * kmem_cache can't change, this tunable can only be modified at boot. Changing 146318946Savg * it at runtime would cause ABD iteration to work incorrectly for ABDs which 147318946Savg * were allocated with the old size, so a safeguard has been put in place which 148318946Savg * will cause the machine to panic if you change it and try to access the data 149318946Savg * within a scattered ABD. 150318946Savg */ 151318946Savgsize_t zfs_abd_chunk_size = 4096; 152318946Savg 153324160Savg#if defined(__FreeBSD__) && defined(_KERNEL) 154324160SavgSYSCTL_DECL(_vfs_zfs); 155324160Savg 156324160SavgSYSCTL_ULONG(_vfs_zfs, OID_AUTO, abd_chunk_size, CTLFLAG_RDTUN, 157324160Savg &zfs_abd_chunk_size, 0, "The size of the chunks ABD allocates"); 158324160Savg#endif 159324160Savg 160318946Savg#ifdef _KERNEL 161318946Savgextern vmem_t *zio_alloc_arena; 162318946Savg#endif 163318946Savg 164318946Savgkmem_cache_t *abd_chunk_cache; 165318946Savgstatic kstat_t *abd_ksp; 166318946Savg 167323760Savgextern inline boolean_t abd_is_linear(abd_t *abd); 168323760Savgextern inline void abd_copy(abd_t *dabd, abd_t *sabd, size_t size); 169323760Savgextern inline void abd_copy_from_buf(abd_t *abd, const void *buf, size_t size); 170323760Savgextern inline void abd_copy_to_buf(void* buf, abd_t *abd, size_t size); 171323760Savgextern inline int abd_cmp_buf(abd_t *abd, const void *buf, size_t size); 172323760Savgextern inline void abd_zero(abd_t *abd, size_t size); 173323760Savg 174318946Savgstatic void * 175318946Savgabd_alloc_chunk() 176318946Savg{ 177318946Savg void *c = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE); 178318946Savg ASSERT3P(c, !=, NULL); 179318946Savg return (c); 180318946Savg} 181318946Savg 182318946Savgstatic void 183318946Savgabd_free_chunk(void *c) 184318946Savg{ 185318946Savg kmem_cache_free(abd_chunk_cache, c); 186318946Savg} 187318946Savg 188318946Savgvoid 189318946Savgabd_init(void) 190318946Savg{ 191320156Savg#ifdef illumos 192318946Savg vmem_t *data_alloc_arena = NULL; 193318946Savg 194318946Savg#ifdef _KERNEL 195318946Savg data_alloc_arena = zio_alloc_arena; 196318946Savg#endif 197318946Savg 198318946Savg /* 199318946Savg * Since ABD chunks do not appear in crash dumps, we pass KMC_NOTOUCH 200318946Savg * so that no allocator metadata is stored with the buffers. 201318946Savg */ 202318946Savg abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0, 203318946Savg NULL, NULL, NULL, NULL, data_alloc_arena, KMC_NOTOUCH); 204320156Savg#else 205320156Savg abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0, 206320156Savg NULL, NULL, NULL, NULL, 0, KMC_NOTOUCH | KMC_NODEBUG); 207320156Savg#endif 208318946Savg abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED, 209318946Savg sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL); 210318946Savg if (abd_ksp != NULL) { 211318946Savg abd_ksp->ks_data = &abd_stats; 212318946Savg kstat_install(abd_ksp); 213318946Savg } 214318946Savg} 215318946Savg 216318946Savgvoid 217318946Savgabd_fini(void) 218318946Savg{ 219318946Savg if (abd_ksp != NULL) { 220318946Savg kstat_delete(abd_ksp); 221318946Savg abd_ksp = NULL; 222318946Savg } 223318946Savg 224318946Savg kmem_cache_destroy(abd_chunk_cache); 225318946Savg abd_chunk_cache = NULL; 226318946Savg} 227318946Savg 228318946Savgstatic inline size_t 229318946Savgabd_chunkcnt_for_bytes(size_t size) 230318946Savg{ 231318946Savg return (P2ROUNDUP(size, zfs_abd_chunk_size) / zfs_abd_chunk_size); 232318946Savg} 233318946Savg 234318946Savgstatic inline size_t 235318946Savgabd_scatter_chunkcnt(abd_t *abd) 236318946Savg{ 237318946Savg ASSERT(!abd_is_linear(abd)); 238318946Savg return (abd_chunkcnt_for_bytes( 239318946Savg abd->abd_u.abd_scatter.abd_offset + abd->abd_size)); 240318946Savg} 241318946Savg 242318946Savgstatic inline void 243318946Savgabd_verify(abd_t *abd) 244318946Savg{ 245318946Savg ASSERT3U(abd->abd_size, >, 0); 246318946Savg ASSERT3U(abd->abd_size, <=, SPA_MAXBLOCKSIZE); 247318946Savg ASSERT3U(abd->abd_flags, ==, abd->abd_flags & (ABD_FLAG_LINEAR | 248318946Savg ABD_FLAG_OWNER | ABD_FLAG_META)); 249318946Savg IMPLY(abd->abd_parent != NULL, !(abd->abd_flags & ABD_FLAG_OWNER)); 250318946Savg IMPLY(abd->abd_flags & ABD_FLAG_META, abd->abd_flags & ABD_FLAG_OWNER); 251318946Savg if (abd_is_linear(abd)) { 252318946Savg ASSERT3P(abd->abd_u.abd_linear.abd_buf, !=, NULL); 253318946Savg } else { 254318946Savg ASSERT3U(abd->abd_u.abd_scatter.abd_offset, <, 255318946Savg zfs_abd_chunk_size); 256318946Savg size_t n = abd_scatter_chunkcnt(abd); 257318946Savg for (int i = 0; i < n; i++) { 258318946Savg ASSERT3P( 259318946Savg abd->abd_u.abd_scatter.abd_chunks[i], !=, NULL); 260318946Savg } 261318946Savg } 262318946Savg} 263318946Savg 264318946Savgstatic inline abd_t * 265318946Savgabd_alloc_struct(size_t chunkcnt) 266318946Savg{ 267318946Savg size_t size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]); 268318946Savg abd_t *abd = kmem_alloc(size, KM_PUSHPAGE); 269318946Savg ASSERT3P(abd, !=, NULL); 270318946Savg ABDSTAT_INCR(abdstat_struct_size, size); 271318946Savg 272318946Savg return (abd); 273318946Savg} 274318946Savg 275318946Savgstatic inline void 276318946Savgabd_free_struct(abd_t *abd) 277318946Savg{ 278318946Savg size_t chunkcnt = abd_is_linear(abd) ? 0 : abd_scatter_chunkcnt(abd); 279318946Savg int size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]); 280318946Savg kmem_free(abd, size); 281318946Savg ABDSTAT_INCR(abdstat_struct_size, -size); 282318946Savg} 283318946Savg 284318946Savg/* 285318946Savg * Allocate an ABD, along with its own underlying data buffers. Use this if you 286318946Savg * don't care whether the ABD is linear or not. 287318946Savg */ 288318946Savgabd_t * 289318946Savgabd_alloc(size_t size, boolean_t is_metadata) 290318946Savg{ 291318946Savg if (!zfs_abd_scatter_enabled) 292318946Savg return (abd_alloc_linear(size, is_metadata)); 293318946Savg 294318946Savg VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); 295318946Savg 296318946Savg size_t n = abd_chunkcnt_for_bytes(size); 297318946Savg abd_t *abd = abd_alloc_struct(n); 298318946Savg 299318946Savg abd->abd_flags = ABD_FLAG_OWNER; 300318946Savg if (is_metadata) { 301318946Savg abd->abd_flags |= ABD_FLAG_META; 302318946Savg } 303318946Savg abd->abd_size = size; 304318946Savg abd->abd_parent = NULL; 305318946Savg refcount_create(&abd->abd_children); 306318946Savg 307318946Savg abd->abd_u.abd_scatter.abd_offset = 0; 308318946Savg abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size; 309318946Savg 310318946Savg for (int i = 0; i < n; i++) { 311318946Savg void *c = abd_alloc_chunk(); 312318946Savg ASSERT3P(c, !=, NULL); 313318946Savg abd->abd_u.abd_scatter.abd_chunks[i] = c; 314318946Savg } 315318946Savg 316318946Savg ABDSTAT_BUMP(abdstat_scatter_cnt); 317318946Savg ABDSTAT_INCR(abdstat_scatter_data_size, size); 318318946Savg ABDSTAT_INCR(abdstat_scatter_chunk_waste, 319318946Savg n * zfs_abd_chunk_size - size); 320318946Savg 321318946Savg return (abd); 322318946Savg} 323318946Savg 324318946Savgstatic void 325318946Savgabd_free_scatter(abd_t *abd) 326318946Savg{ 327318946Savg size_t n = abd_scatter_chunkcnt(abd); 328318946Savg for (int i = 0; i < n; i++) { 329318946Savg abd_free_chunk(abd->abd_u.abd_scatter.abd_chunks[i]); 330318946Savg } 331318946Savg 332318946Savg refcount_destroy(&abd->abd_children); 333318946Savg ABDSTAT_BUMPDOWN(abdstat_scatter_cnt); 334318946Savg ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size); 335318946Savg ABDSTAT_INCR(abdstat_scatter_chunk_waste, 336318946Savg abd->abd_size - n * zfs_abd_chunk_size); 337318946Savg 338318946Savg abd_free_struct(abd); 339318946Savg} 340318946Savg 341318946Savg/* 342318946Savg * Allocate an ABD that must be linear, along with its own underlying data 343318946Savg * buffer. Only use this when it would be very annoying to write your ABD 344318946Savg * consumer with a scattered ABD. 345318946Savg */ 346318946Savgabd_t * 347318946Savgabd_alloc_linear(size_t size, boolean_t is_metadata) 348318946Savg{ 349318946Savg abd_t *abd = abd_alloc_struct(0); 350318946Savg 351318946Savg VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); 352318946Savg 353318946Savg abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER; 354318946Savg if (is_metadata) { 355318946Savg abd->abd_flags |= ABD_FLAG_META; 356318946Savg } 357318946Savg abd->abd_size = size; 358318946Savg abd->abd_parent = NULL; 359318946Savg refcount_create(&abd->abd_children); 360318946Savg 361318946Savg if (is_metadata) { 362318946Savg abd->abd_u.abd_linear.abd_buf = zio_buf_alloc(size); 363318946Savg } else { 364318946Savg abd->abd_u.abd_linear.abd_buf = zio_data_buf_alloc(size); 365318946Savg } 366318946Savg 367318946Savg ABDSTAT_BUMP(abdstat_linear_cnt); 368318946Savg ABDSTAT_INCR(abdstat_linear_data_size, size); 369318946Savg 370318946Savg return (abd); 371318946Savg} 372318946Savg 373318946Savgstatic void 374318946Savgabd_free_linear(abd_t *abd) 375318946Savg{ 376318946Savg if (abd->abd_flags & ABD_FLAG_META) { 377318946Savg zio_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size); 378318946Savg } else { 379318946Savg zio_data_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size); 380318946Savg } 381318946Savg 382318946Savg refcount_destroy(&abd->abd_children); 383318946Savg ABDSTAT_BUMPDOWN(abdstat_linear_cnt); 384318946Savg ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size); 385318946Savg 386318946Savg abd_free_struct(abd); 387318946Savg} 388318946Savg 389318946Savg/* 390318946Savg * Free an ABD. Only use this on ABDs allocated with abd_alloc() or 391318946Savg * abd_alloc_linear(). 392318946Savg */ 393318946Savgvoid 394318946Savgabd_free(abd_t *abd) 395318946Savg{ 396318946Savg abd_verify(abd); 397318946Savg ASSERT3P(abd->abd_parent, ==, NULL); 398318946Savg ASSERT(abd->abd_flags & ABD_FLAG_OWNER); 399318946Savg if (abd_is_linear(abd)) 400318946Savg abd_free_linear(abd); 401318946Savg else 402318946Savg abd_free_scatter(abd); 403318946Savg} 404318946Savg 405318946Savg/* 406318946Savg * Allocate an ABD of the same format (same metadata flag, same scatterize 407318946Savg * setting) as another ABD. 408318946Savg */ 409318946Savgabd_t * 410318946Savgabd_alloc_sametype(abd_t *sabd, size_t size) 411318946Savg{ 412318946Savg boolean_t is_metadata = (sabd->abd_flags & ABD_FLAG_META) != 0; 413318946Savg if (abd_is_linear(sabd)) { 414318946Savg return (abd_alloc_linear(size, is_metadata)); 415318946Savg } else { 416318946Savg return (abd_alloc(size, is_metadata)); 417318946Savg } 418318946Savg} 419318946Savg 420318946Savg/* 421318946Savg * If we're going to use this ABD for doing I/O using the block layer, the 422318946Savg * consumer of the ABD data doesn't care if it's scattered or not, and we don't 423318946Savg * plan to store this ABD in memory for a long period of time, we should 424318946Savg * allocate the ABD type that requires the least data copying to do the I/O. 425318946Savg * 426318946Savg * Currently this is linear ABDs, however if ldi_strategy() can ever issue I/Os 427318946Savg * using a scatter/gather list we should switch to that and replace this call 428318946Savg * with vanilla abd_alloc(). 429318946Savg */ 430318946Savgabd_t * 431318946Savgabd_alloc_for_io(size_t size, boolean_t is_metadata) 432318946Savg{ 433318946Savg return (abd_alloc_linear(size, is_metadata)); 434318946Savg} 435318946Savg 436318946Savg/* 437318946Savg * Allocate a new ABD to point to offset off of sabd. It shares the underlying 438318946Savg * buffer data with sabd. Use abd_put() to free. sabd must not be freed while 439318946Savg * any derived ABDs exist. 440318946Savg */ 441318946Savgabd_t * 442318946Savgabd_get_offset(abd_t *sabd, size_t off) 443318946Savg{ 444318946Savg abd_t *abd; 445318946Savg 446318946Savg abd_verify(sabd); 447318946Savg ASSERT3U(off, <=, sabd->abd_size); 448318946Savg 449318946Savg if (abd_is_linear(sabd)) { 450318946Savg abd = abd_alloc_struct(0); 451318946Savg 452318946Savg /* 453318946Savg * Even if this buf is filesystem metadata, we only track that 454318946Savg * if we own the underlying data buffer, which is not true in 455318946Savg * this case. Therefore, we don't ever use ABD_FLAG_META here. 456318946Savg */ 457318946Savg abd->abd_flags = ABD_FLAG_LINEAR; 458318946Savg 459318946Savg abd->abd_u.abd_linear.abd_buf = 460318946Savg (char *)sabd->abd_u.abd_linear.abd_buf + off; 461318946Savg } else { 462318946Savg size_t new_offset = sabd->abd_u.abd_scatter.abd_offset + off; 463318946Savg size_t chunkcnt = abd_scatter_chunkcnt(sabd) - 464318946Savg (new_offset / zfs_abd_chunk_size); 465318946Savg 466318946Savg abd = abd_alloc_struct(chunkcnt); 467318946Savg 468318946Savg /* 469318946Savg * Even if this buf is filesystem metadata, we only track that 470318946Savg * if we own the underlying data buffer, which is not true in 471318946Savg * this case. Therefore, we don't ever use ABD_FLAG_META here. 472318946Savg */ 473318946Savg abd->abd_flags = 0; 474318946Savg 475318946Savg abd->abd_u.abd_scatter.abd_offset = 476318946Savg new_offset % zfs_abd_chunk_size; 477318946Savg abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size; 478318946Savg 479318946Savg /* Copy the scatterlist starting at the correct offset */ 480318946Savg (void) memcpy(&abd->abd_u.abd_scatter.abd_chunks, 481318946Savg &sabd->abd_u.abd_scatter.abd_chunks[new_offset / 482318946Savg zfs_abd_chunk_size], 483318946Savg chunkcnt * sizeof (void *)); 484318946Savg } 485318946Savg 486318946Savg abd->abd_size = sabd->abd_size - off; 487318946Savg abd->abd_parent = sabd; 488318946Savg refcount_create(&abd->abd_children); 489318946Savg (void) refcount_add_many(&sabd->abd_children, abd->abd_size, abd); 490318946Savg 491318946Savg return (abd); 492318946Savg} 493318946Savg 494318946Savg/* 495318946Savg * Allocate a linear ABD structure for buf. You must free this with abd_put() 496318946Savg * since the resulting ABD doesn't own its own buffer. 497318946Savg */ 498318946Savgabd_t * 499318946Savgabd_get_from_buf(void *buf, size_t size) 500318946Savg{ 501318946Savg abd_t *abd = abd_alloc_struct(0); 502318946Savg 503318946Savg VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); 504318946Savg 505318946Savg /* 506318946Savg * Even if this buf is filesystem metadata, we only track that if we 507318946Savg * own the underlying data buffer, which is not true in this case. 508318946Savg * Therefore, we don't ever use ABD_FLAG_META here. 509318946Savg */ 510318946Savg abd->abd_flags = ABD_FLAG_LINEAR; 511318946Savg abd->abd_size = size; 512318946Savg abd->abd_parent = NULL; 513318946Savg refcount_create(&abd->abd_children); 514318946Savg 515318946Savg abd->abd_u.abd_linear.abd_buf = buf; 516318946Savg 517318946Savg return (abd); 518318946Savg} 519318946Savg 520318946Savg/* 521318946Savg * Free an ABD allocated from abd_get_offset() or abd_get_from_buf(). Will not 522318946Savg * free the underlying scatterlist or buffer. 523318946Savg */ 524318946Savgvoid 525318946Savgabd_put(abd_t *abd) 526318946Savg{ 527318946Savg abd_verify(abd); 528318946Savg ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER)); 529318946Savg 530318946Savg if (abd->abd_parent != NULL) { 531318946Savg (void) refcount_remove_many(&abd->abd_parent->abd_children, 532318946Savg abd->abd_size, abd); 533318946Savg } 534318946Savg 535318946Savg refcount_destroy(&abd->abd_children); 536318946Savg abd_free_struct(abd); 537318946Savg} 538318946Savg 539318946Savg/* 540318946Savg * Get the raw buffer associated with a linear ABD. 541318946Savg */ 542318946Savgvoid * 543318946Savgabd_to_buf(abd_t *abd) 544318946Savg{ 545318946Savg ASSERT(abd_is_linear(abd)); 546318946Savg abd_verify(abd); 547318946Savg return (abd->abd_u.abd_linear.abd_buf); 548318946Savg} 549318946Savg 550318946Savg/* 551318946Savg * Borrow a raw buffer from an ABD without copying the contents of the ABD 552318946Savg * into the buffer. If the ABD is scattered, this will allocate a raw buffer 553318946Savg * whose contents are undefined. To copy over the existing data in the ABD, use 554318946Savg * abd_borrow_buf_copy() instead. 555318946Savg */ 556318946Savgvoid * 557318946Savgabd_borrow_buf(abd_t *abd, size_t n) 558318946Savg{ 559318946Savg void *buf; 560318946Savg abd_verify(abd); 561318946Savg ASSERT3U(abd->abd_size, >=, n); 562318946Savg if (abd_is_linear(abd)) { 563318946Savg buf = abd_to_buf(abd); 564318946Savg } else { 565318946Savg buf = zio_buf_alloc(n); 566318946Savg } 567318946Savg (void) refcount_add_many(&abd->abd_children, n, buf); 568318946Savg 569318946Savg return (buf); 570318946Savg} 571318946Savg 572318946Savgvoid * 573318946Savgabd_borrow_buf_copy(abd_t *abd, size_t n) 574318946Savg{ 575318946Savg void *buf = abd_borrow_buf(abd, n); 576318946Savg if (!abd_is_linear(abd)) { 577318946Savg abd_copy_to_buf(buf, abd, n); 578318946Savg } 579318946Savg return (buf); 580318946Savg} 581318946Savg 582318946Savg/* 583318946Savg * Return a borrowed raw buffer to an ABD. If the ABD is scattered, this will 584318946Savg * not change the contents of the ABD and will ASSERT that you didn't modify 585318946Savg * the buffer since it was borrowed. If you want any changes you made to buf to 586318946Savg * be copied back to abd, use abd_return_buf_copy() instead. 587318946Savg */ 588318946Savgvoid 589318946Savgabd_return_buf(abd_t *abd, void *buf, size_t n) 590318946Savg{ 591318946Savg abd_verify(abd); 592318946Savg ASSERT3U(abd->abd_size, >=, n); 593318946Savg if (abd_is_linear(abd)) { 594318946Savg ASSERT3P(buf, ==, abd_to_buf(abd)); 595318946Savg } else { 596318946Savg ASSERT0(abd_cmp_buf(abd, buf, n)); 597318946Savg zio_buf_free(buf, n); 598318946Savg } 599318946Savg (void) refcount_remove_many(&abd->abd_children, n, buf); 600318946Savg} 601318946Savg 602318946Savgvoid 603318946Savgabd_return_buf_copy(abd_t *abd, void *buf, size_t n) 604318946Savg{ 605318946Savg if (!abd_is_linear(abd)) { 606318946Savg abd_copy_from_buf(abd, buf, n); 607318946Savg } 608318946Savg abd_return_buf(abd, buf, n); 609318946Savg} 610318946Savg 611318946Savg/* 612318946Savg * Give this ABD ownership of the buffer that it's storing. Can only be used on 613318946Savg * linear ABDs which were allocated via abd_get_from_buf(), or ones allocated 614318946Savg * with abd_alloc_linear() which subsequently released ownership of their buf 615318946Savg * with abd_release_ownership_of_buf(). 616318946Savg */ 617318946Savgvoid 618318946Savgabd_take_ownership_of_buf(abd_t *abd, boolean_t is_metadata) 619318946Savg{ 620318946Savg ASSERT(abd_is_linear(abd)); 621318946Savg ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER)); 622318946Savg abd_verify(abd); 623318946Savg 624318946Savg abd->abd_flags |= ABD_FLAG_OWNER; 625318946Savg if (is_metadata) { 626318946Savg abd->abd_flags |= ABD_FLAG_META; 627318946Savg } 628318946Savg 629318946Savg ABDSTAT_BUMP(abdstat_linear_cnt); 630318946Savg ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size); 631318946Savg} 632318946Savg 633318946Savgvoid 634318946Savgabd_release_ownership_of_buf(abd_t *abd) 635318946Savg{ 636318946Savg ASSERT(abd_is_linear(abd)); 637318946Savg ASSERT(abd->abd_flags & ABD_FLAG_OWNER); 638318946Savg abd_verify(abd); 639318946Savg 640318946Savg abd->abd_flags &= ~ABD_FLAG_OWNER; 641318946Savg /* Disable this flag since we no longer own the data buffer */ 642318946Savg abd->abd_flags &= ~ABD_FLAG_META; 643318946Savg 644318946Savg ABDSTAT_BUMPDOWN(abdstat_linear_cnt); 645318946Savg ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size); 646318946Savg} 647318946Savg 648318946Savgstruct abd_iter { 649318946Savg abd_t *iter_abd; /* ABD being iterated through */ 650318946Savg size_t iter_pos; /* position (relative to abd_offset) */ 651318946Savg void *iter_mapaddr; /* addr corresponding to iter_pos */ 652318946Savg size_t iter_mapsize; /* length of data valid at mapaddr */ 653318946Savg}; 654318946Savg 655318946Savgstatic inline size_t 656318946Savgabd_iter_scatter_chunk_offset(struct abd_iter *aiter) 657318946Savg{ 658318946Savg ASSERT(!abd_is_linear(aiter->iter_abd)); 659318946Savg return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset + 660318946Savg aiter->iter_pos) % zfs_abd_chunk_size); 661318946Savg} 662318946Savg 663318946Savgstatic inline size_t 664318946Savgabd_iter_scatter_chunk_index(struct abd_iter *aiter) 665318946Savg{ 666318946Savg ASSERT(!abd_is_linear(aiter->iter_abd)); 667318946Savg return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset + 668318946Savg aiter->iter_pos) / zfs_abd_chunk_size); 669318946Savg} 670318946Savg 671318946Savg/* 672318946Savg * Initialize the abd_iter. 673318946Savg */ 674318946Savgstatic void 675318946Savgabd_iter_init(struct abd_iter *aiter, abd_t *abd) 676318946Savg{ 677318946Savg abd_verify(abd); 678318946Savg aiter->iter_abd = abd; 679318946Savg aiter->iter_pos = 0; 680318946Savg aiter->iter_mapaddr = NULL; 681318946Savg aiter->iter_mapsize = 0; 682318946Savg} 683318946Savg 684318946Savg/* 685318946Savg * Advance the iterator by a certain amount. Cannot be called when a chunk is 686318946Savg * in use. This can be safely called when the aiter has already exhausted, in 687318946Savg * which case this does nothing. 688318946Savg */ 689318946Savgstatic void 690318946Savgabd_iter_advance(struct abd_iter *aiter, size_t amount) 691318946Savg{ 692318946Savg ASSERT3P(aiter->iter_mapaddr, ==, NULL); 693318946Savg ASSERT0(aiter->iter_mapsize); 694318946Savg 695318946Savg /* There's nothing left to advance to, so do nothing */ 696318946Savg if (aiter->iter_pos == aiter->iter_abd->abd_size) 697318946Savg return; 698318946Savg 699318946Savg aiter->iter_pos += amount; 700318946Savg} 701318946Savg 702318946Savg/* 703318946Savg * Map the current chunk into aiter. This can be safely called when the aiter 704318946Savg * has already exhausted, in which case this does nothing. 705318946Savg */ 706318946Savgstatic void 707318946Savgabd_iter_map(struct abd_iter *aiter) 708318946Savg{ 709318946Savg void *paddr; 710318946Savg size_t offset = 0; 711318946Savg 712318946Savg ASSERT3P(aiter->iter_mapaddr, ==, NULL); 713318946Savg ASSERT0(aiter->iter_mapsize); 714318946Savg 715318946Savg /* Panic if someone has changed zfs_abd_chunk_size */ 716318946Savg IMPLY(!abd_is_linear(aiter->iter_abd), zfs_abd_chunk_size == 717318946Savg aiter->iter_abd->abd_u.abd_scatter.abd_chunk_size); 718318946Savg 719318946Savg /* There's nothing left to iterate over, so do nothing */ 720318946Savg if (aiter->iter_pos == aiter->iter_abd->abd_size) 721318946Savg return; 722318946Savg 723318946Savg if (abd_is_linear(aiter->iter_abd)) { 724318946Savg offset = aiter->iter_pos; 725318946Savg aiter->iter_mapsize = aiter->iter_abd->abd_size - offset; 726318946Savg paddr = aiter->iter_abd->abd_u.abd_linear.abd_buf; 727318946Savg } else { 728318946Savg size_t index = abd_iter_scatter_chunk_index(aiter); 729318946Savg offset = abd_iter_scatter_chunk_offset(aiter); 730318946Savg aiter->iter_mapsize = zfs_abd_chunk_size - offset; 731318946Savg paddr = aiter->iter_abd->abd_u.abd_scatter.abd_chunks[index]; 732318946Savg } 733318946Savg aiter->iter_mapaddr = (char *)paddr + offset; 734318946Savg} 735318946Savg 736318946Savg/* 737318946Savg * Unmap the current chunk from aiter. This can be safely called when the aiter 738318946Savg * has already exhausted, in which case this does nothing. 739318946Savg */ 740318946Savgstatic void 741318946Savgabd_iter_unmap(struct abd_iter *aiter) 742318946Savg{ 743318946Savg /* There's nothing left to unmap, so do nothing */ 744318946Savg if (aiter->iter_pos == aiter->iter_abd->abd_size) 745318946Savg return; 746318946Savg 747318946Savg ASSERT3P(aiter->iter_mapaddr, !=, NULL); 748318946Savg ASSERT3U(aiter->iter_mapsize, >, 0); 749318946Savg 750318946Savg aiter->iter_mapaddr = NULL; 751318946Savg aiter->iter_mapsize = 0; 752318946Savg} 753318946Savg 754318946Savgint 755318946Savgabd_iterate_func(abd_t *abd, size_t off, size_t size, 756318946Savg abd_iter_func_t *func, void *private) 757318946Savg{ 758318946Savg int ret = 0; 759318946Savg struct abd_iter aiter; 760318946Savg 761318946Savg abd_verify(abd); 762318946Savg ASSERT3U(off + size, <=, abd->abd_size); 763318946Savg 764318946Savg abd_iter_init(&aiter, abd); 765318946Savg abd_iter_advance(&aiter, off); 766318946Savg 767318946Savg while (size > 0) { 768318946Savg abd_iter_map(&aiter); 769318946Savg 770318946Savg size_t len = MIN(aiter.iter_mapsize, size); 771318946Savg ASSERT3U(len, >, 0); 772318946Savg 773318946Savg ret = func(aiter.iter_mapaddr, len, private); 774318946Savg 775318946Savg abd_iter_unmap(&aiter); 776318946Savg 777318946Savg if (ret != 0) 778318946Savg break; 779318946Savg 780318946Savg size -= len; 781318946Savg abd_iter_advance(&aiter, len); 782318946Savg } 783318946Savg 784318946Savg return (ret); 785318946Savg} 786318946Savg 787318946Savgstruct buf_arg { 788318946Savg void *arg_buf; 789318946Savg}; 790318946Savg 791318946Savgstatic int 792318946Savgabd_copy_to_buf_off_cb(void *buf, size_t size, void *private) 793318946Savg{ 794318946Savg struct buf_arg *ba_ptr = private; 795318946Savg 796318946Savg (void) memcpy(ba_ptr->arg_buf, buf, size); 797318946Savg ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; 798318946Savg 799318946Savg return (0); 800318946Savg} 801318946Savg 802318946Savg/* 803318946Savg * Copy abd to buf. (off is the offset in abd.) 804318946Savg */ 805318946Savgvoid 806318946Savgabd_copy_to_buf_off(void *buf, abd_t *abd, size_t off, size_t size) 807318946Savg{ 808318946Savg struct buf_arg ba_ptr = { buf }; 809318946Savg 810318946Savg (void) abd_iterate_func(abd, off, size, abd_copy_to_buf_off_cb, 811318946Savg &ba_ptr); 812318946Savg} 813318946Savg 814318946Savgstatic int 815318946Savgabd_cmp_buf_off_cb(void *buf, size_t size, void *private) 816318946Savg{ 817318946Savg int ret; 818318946Savg struct buf_arg *ba_ptr = private; 819318946Savg 820318946Savg ret = memcmp(buf, ba_ptr->arg_buf, size); 821318946Savg ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; 822318946Savg 823318946Savg return (ret); 824318946Savg} 825318946Savg 826318946Savg/* 827318946Savg * Compare the contents of abd to buf. (off is the offset in abd.) 828318946Savg */ 829318946Savgint 830318946Savgabd_cmp_buf_off(abd_t *abd, const void *buf, size_t off, size_t size) 831318946Savg{ 832318946Savg struct buf_arg ba_ptr = { (void *) buf }; 833318946Savg 834318946Savg return (abd_iterate_func(abd, off, size, abd_cmp_buf_off_cb, &ba_ptr)); 835318946Savg} 836318946Savg 837318946Savgstatic int 838318946Savgabd_copy_from_buf_off_cb(void *buf, size_t size, void *private) 839318946Savg{ 840318946Savg struct buf_arg *ba_ptr = private; 841318946Savg 842318946Savg (void) memcpy(buf, ba_ptr->arg_buf, size); 843318946Savg ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; 844318946Savg 845318946Savg return (0); 846318946Savg} 847318946Savg 848318946Savg/* 849318946Savg * Copy from buf to abd. (off is the offset in abd.) 850318946Savg */ 851318946Savgvoid 852318946Savgabd_copy_from_buf_off(abd_t *abd, const void *buf, size_t off, size_t size) 853318946Savg{ 854318946Savg struct buf_arg ba_ptr = { (void *) buf }; 855318946Savg 856318946Savg (void) abd_iterate_func(abd, off, size, abd_copy_from_buf_off_cb, 857318946Savg &ba_ptr); 858318946Savg} 859318946Savg 860318946Savg/*ARGSUSED*/ 861318946Savgstatic int 862318946Savgabd_zero_off_cb(void *buf, size_t size, void *private) 863318946Savg{ 864318946Savg (void) memset(buf, 0, size); 865318946Savg return (0); 866318946Savg} 867318946Savg 868318946Savg/* 869318946Savg * Zero out the abd from a particular offset to the end. 870318946Savg */ 871318946Savgvoid 872318946Savgabd_zero_off(abd_t *abd, size_t off, size_t size) 873318946Savg{ 874318946Savg (void) abd_iterate_func(abd, off, size, abd_zero_off_cb, NULL); 875318946Savg} 876318946Savg 877318946Savg/* 878318946Savg * Iterate over two ABDs and call func incrementally on the two ABDs' data in 879318946Savg * equal-sized chunks (passed to func as raw buffers). func could be called many 880318946Savg * times during this iteration. 881318946Savg */ 882318946Savgint 883318946Savgabd_iterate_func2(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, 884318946Savg size_t size, abd_iter_func2_t *func, void *private) 885318946Savg{ 886318946Savg int ret = 0; 887318946Savg struct abd_iter daiter, saiter; 888318946Savg 889318946Savg abd_verify(dabd); 890318946Savg abd_verify(sabd); 891318946Savg 892318946Savg ASSERT3U(doff + size, <=, dabd->abd_size); 893318946Savg ASSERT3U(soff + size, <=, sabd->abd_size); 894318946Savg 895318946Savg abd_iter_init(&daiter, dabd); 896318946Savg abd_iter_init(&saiter, sabd); 897318946Savg abd_iter_advance(&daiter, doff); 898318946Savg abd_iter_advance(&saiter, soff); 899318946Savg 900318946Savg while (size > 0) { 901318946Savg abd_iter_map(&daiter); 902318946Savg abd_iter_map(&saiter); 903318946Savg 904318946Savg size_t dlen = MIN(daiter.iter_mapsize, size); 905318946Savg size_t slen = MIN(saiter.iter_mapsize, size); 906318946Savg size_t len = MIN(dlen, slen); 907318946Savg ASSERT(dlen > 0 || slen > 0); 908318946Savg 909318946Savg ret = func(daiter.iter_mapaddr, saiter.iter_mapaddr, len, 910318946Savg private); 911318946Savg 912318946Savg abd_iter_unmap(&saiter); 913318946Savg abd_iter_unmap(&daiter); 914318946Savg 915318946Savg if (ret != 0) 916318946Savg break; 917318946Savg 918318946Savg size -= len; 919318946Savg abd_iter_advance(&daiter, len); 920318946Savg abd_iter_advance(&saiter, len); 921318946Savg } 922318946Savg 923318946Savg return (ret); 924318946Savg} 925318946Savg 926318946Savg/*ARGSUSED*/ 927318946Savgstatic int 928318946Savgabd_copy_off_cb(void *dbuf, void *sbuf, size_t size, void *private) 929318946Savg{ 930318946Savg (void) memcpy(dbuf, sbuf, size); 931318946Savg return (0); 932318946Savg} 933318946Savg 934318946Savg/* 935318946Savg * Copy from sabd to dabd starting from soff and doff. 936318946Savg */ 937318946Savgvoid 938318946Savgabd_copy_off(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size) 939318946Savg{ 940318946Savg (void) abd_iterate_func2(dabd, sabd, doff, soff, size, 941318946Savg abd_copy_off_cb, NULL); 942318946Savg} 943318946Savg 944318946Savg/*ARGSUSED*/ 945318946Savgstatic int 946318946Savgabd_cmp_cb(void *bufa, void *bufb, size_t size, void *private) 947318946Savg{ 948318946Savg return (memcmp(bufa, bufb, size)); 949318946Savg} 950318946Savg 951318946Savg/* 952318946Savg * Compares the first size bytes of two ABDs. 953318946Savg */ 954318946Savgint 955318946Savgabd_cmp(abd_t *dabd, abd_t *sabd, size_t size) 956318946Savg{ 957318946Savg return (abd_iterate_func2(dabd, sabd, 0, 0, size, abd_cmp_cb, NULL)); 958318946Savg} 959