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 156338425SmarkjSYSCTL_INT(_vfs_zfs, OID_AUTO, abd_scatter_enabled, CTLFLAG_RWTUN, 157338425Smarkj &zfs_abd_scatter_enabled, 0, "Enable scattered ARC data buffers"); 158324160SavgSYSCTL_ULONG(_vfs_zfs, OID_AUTO, abd_chunk_size, CTLFLAG_RDTUN, 159324160Savg &zfs_abd_chunk_size, 0, "The size of the chunks ABD allocates"); 160324160Savg#endif 161324160Savg 162318946Savg#ifdef _KERNEL 163318946Savgextern vmem_t *zio_alloc_arena; 164318946Savg#endif 165318946Savg 166318946Savgkmem_cache_t *abd_chunk_cache; 167318946Savgstatic kstat_t *abd_ksp; 168318946Savg 169323760Savgextern inline boolean_t abd_is_linear(abd_t *abd); 170323760Savgextern inline void abd_copy(abd_t *dabd, abd_t *sabd, size_t size); 171323760Savgextern inline void abd_copy_from_buf(abd_t *abd, const void *buf, size_t size); 172323760Savgextern inline void abd_copy_to_buf(void* buf, abd_t *abd, size_t size); 173323760Savgextern inline int abd_cmp_buf(abd_t *abd, const void *buf, size_t size); 174323760Savgextern inline void abd_zero(abd_t *abd, size_t size); 175323760Savg 176318946Savgstatic void * 177318946Savgabd_alloc_chunk() 178318946Savg{ 179318946Savg void *c = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE); 180318946Savg ASSERT3P(c, !=, NULL); 181318946Savg return (c); 182318946Savg} 183318946Savg 184318946Savgstatic void 185318946Savgabd_free_chunk(void *c) 186318946Savg{ 187318946Savg kmem_cache_free(abd_chunk_cache, c); 188318946Savg} 189318946Savg 190318946Savgvoid 191318946Savgabd_init(void) 192318946Savg{ 193320156Savg#ifdef illumos 194318946Savg vmem_t *data_alloc_arena = NULL; 195318946Savg 196318946Savg#ifdef _KERNEL 197318946Savg data_alloc_arena = zio_alloc_arena; 198318946Savg#endif 199318946Savg 200318946Savg /* 201318946Savg * Since ABD chunks do not appear in crash dumps, we pass KMC_NOTOUCH 202318946Savg * so that no allocator metadata is stored with the buffers. 203318946Savg */ 204318946Savg abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0, 205318946Savg NULL, NULL, NULL, NULL, data_alloc_arena, KMC_NOTOUCH); 206320156Savg#else 207320156Savg abd_chunk_cache = kmem_cache_create("abd_chunk", zfs_abd_chunk_size, 0, 208320156Savg NULL, NULL, NULL, NULL, 0, KMC_NOTOUCH | KMC_NODEBUG); 209320156Savg#endif 210318946Savg abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED, 211318946Savg sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL); 212318946Savg if (abd_ksp != NULL) { 213318946Savg abd_ksp->ks_data = &abd_stats; 214318946Savg kstat_install(abd_ksp); 215318946Savg } 216318946Savg} 217318946Savg 218318946Savgvoid 219318946Savgabd_fini(void) 220318946Savg{ 221318946Savg if (abd_ksp != NULL) { 222318946Savg kstat_delete(abd_ksp); 223318946Savg abd_ksp = NULL; 224318946Savg } 225318946Savg 226318946Savg kmem_cache_destroy(abd_chunk_cache); 227318946Savg abd_chunk_cache = NULL; 228318946Savg} 229318946Savg 230318946Savgstatic inline size_t 231318946Savgabd_chunkcnt_for_bytes(size_t size) 232318946Savg{ 233318946Savg return (P2ROUNDUP(size, zfs_abd_chunk_size) / zfs_abd_chunk_size); 234318946Savg} 235318946Savg 236318946Savgstatic inline size_t 237318946Savgabd_scatter_chunkcnt(abd_t *abd) 238318946Savg{ 239318946Savg ASSERT(!abd_is_linear(abd)); 240318946Savg return (abd_chunkcnt_for_bytes( 241318946Savg abd->abd_u.abd_scatter.abd_offset + abd->abd_size)); 242318946Savg} 243318946Savg 244318946Savgstatic inline void 245318946Savgabd_verify(abd_t *abd) 246318946Savg{ 247318946Savg ASSERT3U(abd->abd_size, >, 0); 248318946Savg ASSERT3U(abd->abd_size, <=, SPA_MAXBLOCKSIZE); 249318946Savg ASSERT3U(abd->abd_flags, ==, abd->abd_flags & (ABD_FLAG_LINEAR | 250318946Savg ABD_FLAG_OWNER | ABD_FLAG_META)); 251318946Savg IMPLY(abd->abd_parent != NULL, !(abd->abd_flags & ABD_FLAG_OWNER)); 252318946Savg IMPLY(abd->abd_flags & ABD_FLAG_META, abd->abd_flags & ABD_FLAG_OWNER); 253318946Savg if (abd_is_linear(abd)) { 254318946Savg ASSERT3P(abd->abd_u.abd_linear.abd_buf, !=, NULL); 255318946Savg } else { 256318946Savg ASSERT3U(abd->abd_u.abd_scatter.abd_offset, <, 257318946Savg zfs_abd_chunk_size); 258318946Savg size_t n = abd_scatter_chunkcnt(abd); 259318946Savg for (int i = 0; i < n; i++) { 260318946Savg ASSERT3P( 261318946Savg abd->abd_u.abd_scatter.abd_chunks[i], !=, NULL); 262318946Savg } 263318946Savg } 264318946Savg} 265318946Savg 266318946Savgstatic inline abd_t * 267318946Savgabd_alloc_struct(size_t chunkcnt) 268318946Savg{ 269318946Savg size_t size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]); 270318946Savg abd_t *abd = kmem_alloc(size, KM_PUSHPAGE); 271318946Savg ASSERT3P(abd, !=, NULL); 272318946Savg ABDSTAT_INCR(abdstat_struct_size, size); 273318946Savg 274318946Savg return (abd); 275318946Savg} 276318946Savg 277318946Savgstatic inline void 278318946Savgabd_free_struct(abd_t *abd) 279318946Savg{ 280318946Savg size_t chunkcnt = abd_is_linear(abd) ? 0 : abd_scatter_chunkcnt(abd); 281318946Savg int size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]); 282318946Savg kmem_free(abd, size); 283318946Savg ABDSTAT_INCR(abdstat_struct_size, -size); 284318946Savg} 285318946Savg 286318946Savg/* 287318946Savg * Allocate an ABD, along with its own underlying data buffers. Use this if you 288318946Savg * don't care whether the ABD is linear or not. 289318946Savg */ 290318946Savgabd_t * 291318946Savgabd_alloc(size_t size, boolean_t is_metadata) 292318946Savg{ 293318946Savg if (!zfs_abd_scatter_enabled) 294318946Savg return (abd_alloc_linear(size, is_metadata)); 295318946Savg 296318946Savg VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); 297318946Savg 298318946Savg size_t n = abd_chunkcnt_for_bytes(size); 299318946Savg abd_t *abd = abd_alloc_struct(n); 300318946Savg 301318946Savg abd->abd_flags = ABD_FLAG_OWNER; 302318946Savg if (is_metadata) { 303318946Savg abd->abd_flags |= ABD_FLAG_META; 304318946Savg } 305318946Savg abd->abd_size = size; 306318946Savg abd->abd_parent = NULL; 307318946Savg refcount_create(&abd->abd_children); 308318946Savg 309318946Savg abd->abd_u.abd_scatter.abd_offset = 0; 310318946Savg abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size; 311318946Savg 312318946Savg for (int i = 0; i < n; i++) { 313318946Savg void *c = abd_alloc_chunk(); 314318946Savg ASSERT3P(c, !=, NULL); 315318946Savg abd->abd_u.abd_scatter.abd_chunks[i] = c; 316318946Savg } 317318946Savg 318318946Savg ABDSTAT_BUMP(abdstat_scatter_cnt); 319318946Savg ABDSTAT_INCR(abdstat_scatter_data_size, size); 320318946Savg ABDSTAT_INCR(abdstat_scatter_chunk_waste, 321318946Savg n * zfs_abd_chunk_size - size); 322318946Savg 323318946Savg return (abd); 324318946Savg} 325318946Savg 326318946Savgstatic void 327318946Savgabd_free_scatter(abd_t *abd) 328318946Savg{ 329318946Savg size_t n = abd_scatter_chunkcnt(abd); 330318946Savg for (int i = 0; i < n; i++) { 331318946Savg abd_free_chunk(abd->abd_u.abd_scatter.abd_chunks[i]); 332318946Savg } 333318946Savg 334318946Savg refcount_destroy(&abd->abd_children); 335318946Savg ABDSTAT_BUMPDOWN(abdstat_scatter_cnt); 336318946Savg ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size); 337318946Savg ABDSTAT_INCR(abdstat_scatter_chunk_waste, 338318946Savg abd->abd_size - n * zfs_abd_chunk_size); 339318946Savg 340318946Savg abd_free_struct(abd); 341318946Savg} 342318946Savg 343318946Savg/* 344318946Savg * Allocate an ABD that must be linear, along with its own underlying data 345318946Savg * buffer. Only use this when it would be very annoying to write your ABD 346318946Savg * consumer with a scattered ABD. 347318946Savg */ 348318946Savgabd_t * 349318946Savgabd_alloc_linear(size_t size, boolean_t is_metadata) 350318946Savg{ 351318946Savg abd_t *abd = abd_alloc_struct(0); 352318946Savg 353318946Savg VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); 354318946Savg 355318946Savg abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER; 356318946Savg if (is_metadata) { 357318946Savg abd->abd_flags |= ABD_FLAG_META; 358318946Savg } 359318946Savg abd->abd_size = size; 360318946Savg abd->abd_parent = NULL; 361318946Savg refcount_create(&abd->abd_children); 362318946Savg 363318946Savg if (is_metadata) { 364318946Savg abd->abd_u.abd_linear.abd_buf = zio_buf_alloc(size); 365318946Savg } else { 366318946Savg abd->abd_u.abd_linear.abd_buf = zio_data_buf_alloc(size); 367318946Savg } 368318946Savg 369318946Savg ABDSTAT_BUMP(abdstat_linear_cnt); 370318946Savg ABDSTAT_INCR(abdstat_linear_data_size, size); 371318946Savg 372318946Savg return (abd); 373318946Savg} 374318946Savg 375318946Savgstatic void 376318946Savgabd_free_linear(abd_t *abd) 377318946Savg{ 378318946Savg if (abd->abd_flags & ABD_FLAG_META) { 379318946Savg zio_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size); 380318946Savg } else { 381318946Savg zio_data_buf_free(abd->abd_u.abd_linear.abd_buf, abd->abd_size); 382318946Savg } 383318946Savg 384318946Savg refcount_destroy(&abd->abd_children); 385318946Savg ABDSTAT_BUMPDOWN(abdstat_linear_cnt); 386318946Savg ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size); 387318946Savg 388318946Savg abd_free_struct(abd); 389318946Savg} 390318946Savg 391318946Savg/* 392318946Savg * Free an ABD. Only use this on ABDs allocated with abd_alloc() or 393318946Savg * abd_alloc_linear(). 394318946Savg */ 395318946Savgvoid 396318946Savgabd_free(abd_t *abd) 397318946Savg{ 398318946Savg abd_verify(abd); 399318946Savg ASSERT3P(abd->abd_parent, ==, NULL); 400318946Savg ASSERT(abd->abd_flags & ABD_FLAG_OWNER); 401318946Savg if (abd_is_linear(abd)) 402318946Savg abd_free_linear(abd); 403318946Savg else 404318946Savg abd_free_scatter(abd); 405318946Savg} 406318946Savg 407318946Savg/* 408318946Savg * Allocate an ABD of the same format (same metadata flag, same scatterize 409318946Savg * setting) as another ABD. 410318946Savg */ 411318946Savgabd_t * 412318946Savgabd_alloc_sametype(abd_t *sabd, size_t size) 413318946Savg{ 414318946Savg boolean_t is_metadata = (sabd->abd_flags & ABD_FLAG_META) != 0; 415318946Savg if (abd_is_linear(sabd)) { 416318946Savg return (abd_alloc_linear(size, is_metadata)); 417318946Savg } else { 418318946Savg return (abd_alloc(size, is_metadata)); 419318946Savg } 420318946Savg} 421318946Savg 422318946Savg/* 423318946Savg * If we're going to use this ABD for doing I/O using the block layer, the 424318946Savg * consumer of the ABD data doesn't care if it's scattered or not, and we don't 425318946Savg * plan to store this ABD in memory for a long period of time, we should 426318946Savg * allocate the ABD type that requires the least data copying to do the I/O. 427318946Savg * 428318946Savg * Currently this is linear ABDs, however if ldi_strategy() can ever issue I/Os 429318946Savg * using a scatter/gather list we should switch to that and replace this call 430318946Savg * with vanilla abd_alloc(). 431318946Savg */ 432318946Savgabd_t * 433318946Savgabd_alloc_for_io(size_t size, boolean_t is_metadata) 434318946Savg{ 435318946Savg return (abd_alloc_linear(size, is_metadata)); 436318946Savg} 437318946Savg 438318946Savg/* 439318946Savg * Allocate a new ABD to point to offset off of sabd. It shares the underlying 440318946Savg * buffer data with sabd. Use abd_put() to free. sabd must not be freed while 441318946Savg * any derived ABDs exist. 442318946Savg */ 443318946Savgabd_t * 444318946Savgabd_get_offset(abd_t *sabd, size_t off) 445318946Savg{ 446318946Savg abd_t *abd; 447318946Savg 448318946Savg abd_verify(sabd); 449318946Savg ASSERT3U(off, <=, sabd->abd_size); 450318946Savg 451318946Savg if (abd_is_linear(sabd)) { 452318946Savg abd = abd_alloc_struct(0); 453318946Savg 454318946Savg /* 455318946Savg * Even if this buf is filesystem metadata, we only track that 456318946Savg * if we own the underlying data buffer, which is not true in 457318946Savg * this case. Therefore, we don't ever use ABD_FLAG_META here. 458318946Savg */ 459318946Savg abd->abd_flags = ABD_FLAG_LINEAR; 460318946Savg 461318946Savg abd->abd_u.abd_linear.abd_buf = 462318946Savg (char *)sabd->abd_u.abd_linear.abd_buf + off; 463318946Savg } else { 464318946Savg size_t new_offset = sabd->abd_u.abd_scatter.abd_offset + off; 465318946Savg size_t chunkcnt = abd_scatter_chunkcnt(sabd) - 466318946Savg (new_offset / zfs_abd_chunk_size); 467318946Savg 468318946Savg abd = abd_alloc_struct(chunkcnt); 469318946Savg 470318946Savg /* 471318946Savg * Even if this buf is filesystem metadata, we only track that 472318946Savg * if we own the underlying data buffer, which is not true in 473318946Savg * this case. Therefore, we don't ever use ABD_FLAG_META here. 474318946Savg */ 475318946Savg abd->abd_flags = 0; 476318946Savg 477318946Savg abd->abd_u.abd_scatter.abd_offset = 478318946Savg new_offset % zfs_abd_chunk_size; 479318946Savg abd->abd_u.abd_scatter.abd_chunk_size = zfs_abd_chunk_size; 480318946Savg 481318946Savg /* Copy the scatterlist starting at the correct offset */ 482318946Savg (void) memcpy(&abd->abd_u.abd_scatter.abd_chunks, 483318946Savg &sabd->abd_u.abd_scatter.abd_chunks[new_offset / 484318946Savg zfs_abd_chunk_size], 485318946Savg chunkcnt * sizeof (void *)); 486318946Savg } 487318946Savg 488318946Savg abd->abd_size = sabd->abd_size - off; 489318946Savg abd->abd_parent = sabd; 490318946Savg refcount_create(&abd->abd_children); 491318946Savg (void) refcount_add_many(&sabd->abd_children, abd->abd_size, abd); 492318946Savg 493318946Savg return (abd); 494318946Savg} 495318946Savg 496318946Savg/* 497318946Savg * Allocate a linear ABD structure for buf. You must free this with abd_put() 498318946Savg * since the resulting ABD doesn't own its own buffer. 499318946Savg */ 500318946Savgabd_t * 501318946Savgabd_get_from_buf(void *buf, size_t size) 502318946Savg{ 503318946Savg abd_t *abd = abd_alloc_struct(0); 504318946Savg 505318946Savg VERIFY3U(size, <=, SPA_MAXBLOCKSIZE); 506318946Savg 507318946Savg /* 508318946Savg * Even if this buf is filesystem metadata, we only track that if we 509318946Savg * own the underlying data buffer, which is not true in this case. 510318946Savg * Therefore, we don't ever use ABD_FLAG_META here. 511318946Savg */ 512318946Savg abd->abd_flags = ABD_FLAG_LINEAR; 513318946Savg abd->abd_size = size; 514318946Savg abd->abd_parent = NULL; 515318946Savg refcount_create(&abd->abd_children); 516318946Savg 517318946Savg abd->abd_u.abd_linear.abd_buf = buf; 518318946Savg 519318946Savg return (abd); 520318946Savg} 521318946Savg 522318946Savg/* 523318946Savg * Free an ABD allocated from abd_get_offset() or abd_get_from_buf(). Will not 524318946Savg * free the underlying scatterlist or buffer. 525318946Savg */ 526318946Savgvoid 527318946Savgabd_put(abd_t *abd) 528318946Savg{ 529318946Savg abd_verify(abd); 530318946Savg ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER)); 531318946Savg 532318946Savg if (abd->abd_parent != NULL) { 533318946Savg (void) refcount_remove_many(&abd->abd_parent->abd_children, 534318946Savg abd->abd_size, abd); 535318946Savg } 536318946Savg 537318946Savg refcount_destroy(&abd->abd_children); 538318946Savg abd_free_struct(abd); 539318946Savg} 540318946Savg 541318946Savg/* 542318946Savg * Get the raw buffer associated with a linear ABD. 543318946Savg */ 544318946Savgvoid * 545318946Savgabd_to_buf(abd_t *abd) 546318946Savg{ 547318946Savg ASSERT(abd_is_linear(abd)); 548318946Savg abd_verify(abd); 549318946Savg return (abd->abd_u.abd_linear.abd_buf); 550318946Savg} 551318946Savg 552318946Savg/* 553318946Savg * Borrow a raw buffer from an ABD without copying the contents of the ABD 554318946Savg * into the buffer. If the ABD is scattered, this will allocate a raw buffer 555318946Savg * whose contents are undefined. To copy over the existing data in the ABD, use 556318946Savg * abd_borrow_buf_copy() instead. 557318946Savg */ 558318946Savgvoid * 559318946Savgabd_borrow_buf(abd_t *abd, size_t n) 560318946Savg{ 561318946Savg void *buf; 562318946Savg abd_verify(abd); 563318946Savg ASSERT3U(abd->abd_size, >=, n); 564318946Savg if (abd_is_linear(abd)) { 565318946Savg buf = abd_to_buf(abd); 566318946Savg } else { 567318946Savg buf = zio_buf_alloc(n); 568318946Savg } 569318946Savg (void) refcount_add_many(&abd->abd_children, n, buf); 570318946Savg 571318946Savg return (buf); 572318946Savg} 573318946Savg 574318946Savgvoid * 575318946Savgabd_borrow_buf_copy(abd_t *abd, size_t n) 576318946Savg{ 577318946Savg void *buf = abd_borrow_buf(abd, n); 578318946Savg if (!abd_is_linear(abd)) { 579318946Savg abd_copy_to_buf(buf, abd, n); 580318946Savg } 581318946Savg return (buf); 582318946Savg} 583318946Savg 584318946Savg/* 585318946Savg * Return a borrowed raw buffer to an ABD. If the ABD is scattered, this will 586318946Savg * not change the contents of the ABD and will ASSERT that you didn't modify 587318946Savg * the buffer since it was borrowed. If you want any changes you made to buf to 588318946Savg * be copied back to abd, use abd_return_buf_copy() instead. 589318946Savg */ 590318946Savgvoid 591318946Savgabd_return_buf(abd_t *abd, void *buf, size_t n) 592318946Savg{ 593318946Savg abd_verify(abd); 594318946Savg ASSERT3U(abd->abd_size, >=, n); 595318946Savg if (abd_is_linear(abd)) { 596318946Savg ASSERT3P(buf, ==, abd_to_buf(abd)); 597318946Savg } else { 598318946Savg ASSERT0(abd_cmp_buf(abd, buf, n)); 599318946Savg zio_buf_free(buf, n); 600318946Savg } 601318946Savg (void) refcount_remove_many(&abd->abd_children, n, buf); 602318946Savg} 603318946Savg 604318946Savgvoid 605318946Savgabd_return_buf_copy(abd_t *abd, void *buf, size_t n) 606318946Savg{ 607318946Savg if (!abd_is_linear(abd)) { 608318946Savg abd_copy_from_buf(abd, buf, n); 609318946Savg } 610318946Savg abd_return_buf(abd, buf, n); 611318946Savg} 612318946Savg 613318946Savg/* 614318946Savg * Give this ABD ownership of the buffer that it's storing. Can only be used on 615318946Savg * linear ABDs which were allocated via abd_get_from_buf(), or ones allocated 616318946Savg * with abd_alloc_linear() which subsequently released ownership of their buf 617318946Savg * with abd_release_ownership_of_buf(). 618318946Savg */ 619318946Savgvoid 620318946Savgabd_take_ownership_of_buf(abd_t *abd, boolean_t is_metadata) 621318946Savg{ 622318946Savg ASSERT(abd_is_linear(abd)); 623318946Savg ASSERT(!(abd->abd_flags & ABD_FLAG_OWNER)); 624318946Savg abd_verify(abd); 625318946Savg 626318946Savg abd->abd_flags |= ABD_FLAG_OWNER; 627318946Savg if (is_metadata) { 628318946Savg abd->abd_flags |= ABD_FLAG_META; 629318946Savg } 630318946Savg 631318946Savg ABDSTAT_BUMP(abdstat_linear_cnt); 632318946Savg ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size); 633318946Savg} 634318946Savg 635318946Savgvoid 636318946Savgabd_release_ownership_of_buf(abd_t *abd) 637318946Savg{ 638318946Savg ASSERT(abd_is_linear(abd)); 639318946Savg ASSERT(abd->abd_flags & ABD_FLAG_OWNER); 640318946Savg abd_verify(abd); 641318946Savg 642318946Savg abd->abd_flags &= ~ABD_FLAG_OWNER; 643318946Savg /* Disable this flag since we no longer own the data buffer */ 644318946Savg abd->abd_flags &= ~ABD_FLAG_META; 645318946Savg 646318946Savg ABDSTAT_BUMPDOWN(abdstat_linear_cnt); 647318946Savg ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size); 648318946Savg} 649318946Savg 650318946Savgstruct abd_iter { 651318946Savg abd_t *iter_abd; /* ABD being iterated through */ 652318946Savg size_t iter_pos; /* position (relative to abd_offset) */ 653318946Savg void *iter_mapaddr; /* addr corresponding to iter_pos */ 654318946Savg size_t iter_mapsize; /* length of data valid at mapaddr */ 655318946Savg}; 656318946Savg 657318946Savgstatic inline size_t 658318946Savgabd_iter_scatter_chunk_offset(struct abd_iter *aiter) 659318946Savg{ 660318946Savg ASSERT(!abd_is_linear(aiter->iter_abd)); 661318946Savg return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset + 662318946Savg aiter->iter_pos) % zfs_abd_chunk_size); 663318946Savg} 664318946Savg 665318946Savgstatic inline size_t 666318946Savgabd_iter_scatter_chunk_index(struct abd_iter *aiter) 667318946Savg{ 668318946Savg ASSERT(!abd_is_linear(aiter->iter_abd)); 669318946Savg return ((aiter->iter_abd->abd_u.abd_scatter.abd_offset + 670318946Savg aiter->iter_pos) / zfs_abd_chunk_size); 671318946Savg} 672318946Savg 673318946Savg/* 674318946Savg * Initialize the abd_iter. 675318946Savg */ 676318946Savgstatic void 677318946Savgabd_iter_init(struct abd_iter *aiter, abd_t *abd) 678318946Savg{ 679318946Savg abd_verify(abd); 680318946Savg aiter->iter_abd = abd; 681318946Savg aiter->iter_pos = 0; 682318946Savg aiter->iter_mapaddr = NULL; 683318946Savg aiter->iter_mapsize = 0; 684318946Savg} 685318946Savg 686318946Savg/* 687318946Savg * Advance the iterator by a certain amount. Cannot be called when a chunk is 688318946Savg * in use. This can be safely called when the aiter has already exhausted, in 689318946Savg * which case this does nothing. 690318946Savg */ 691318946Savgstatic void 692318946Savgabd_iter_advance(struct abd_iter *aiter, size_t amount) 693318946Savg{ 694318946Savg ASSERT3P(aiter->iter_mapaddr, ==, NULL); 695318946Savg ASSERT0(aiter->iter_mapsize); 696318946Savg 697318946Savg /* There's nothing left to advance to, so do nothing */ 698318946Savg if (aiter->iter_pos == aiter->iter_abd->abd_size) 699318946Savg return; 700318946Savg 701318946Savg aiter->iter_pos += amount; 702318946Savg} 703318946Savg 704318946Savg/* 705318946Savg * Map the current chunk into aiter. This can be safely called when the aiter 706318946Savg * has already exhausted, in which case this does nothing. 707318946Savg */ 708318946Savgstatic void 709318946Savgabd_iter_map(struct abd_iter *aiter) 710318946Savg{ 711318946Savg void *paddr; 712318946Savg size_t offset = 0; 713318946Savg 714318946Savg ASSERT3P(aiter->iter_mapaddr, ==, NULL); 715318946Savg ASSERT0(aiter->iter_mapsize); 716318946Savg 717318946Savg /* Panic if someone has changed zfs_abd_chunk_size */ 718318946Savg IMPLY(!abd_is_linear(aiter->iter_abd), zfs_abd_chunk_size == 719318946Savg aiter->iter_abd->abd_u.abd_scatter.abd_chunk_size); 720318946Savg 721318946Savg /* There's nothing left to iterate over, so do nothing */ 722318946Savg if (aiter->iter_pos == aiter->iter_abd->abd_size) 723318946Savg return; 724318946Savg 725318946Savg if (abd_is_linear(aiter->iter_abd)) { 726318946Savg offset = aiter->iter_pos; 727318946Savg aiter->iter_mapsize = aiter->iter_abd->abd_size - offset; 728318946Savg paddr = aiter->iter_abd->abd_u.abd_linear.abd_buf; 729318946Savg } else { 730318946Savg size_t index = abd_iter_scatter_chunk_index(aiter); 731318946Savg offset = abd_iter_scatter_chunk_offset(aiter); 732318946Savg aiter->iter_mapsize = zfs_abd_chunk_size - offset; 733318946Savg paddr = aiter->iter_abd->abd_u.abd_scatter.abd_chunks[index]; 734318946Savg } 735318946Savg aiter->iter_mapaddr = (char *)paddr + offset; 736318946Savg} 737318946Savg 738318946Savg/* 739318946Savg * Unmap the current chunk from aiter. This can be safely called when the aiter 740318946Savg * has already exhausted, in which case this does nothing. 741318946Savg */ 742318946Savgstatic void 743318946Savgabd_iter_unmap(struct abd_iter *aiter) 744318946Savg{ 745318946Savg /* There's nothing left to unmap, so do nothing */ 746318946Savg if (aiter->iter_pos == aiter->iter_abd->abd_size) 747318946Savg return; 748318946Savg 749318946Savg ASSERT3P(aiter->iter_mapaddr, !=, NULL); 750318946Savg ASSERT3U(aiter->iter_mapsize, >, 0); 751318946Savg 752318946Savg aiter->iter_mapaddr = NULL; 753318946Savg aiter->iter_mapsize = 0; 754318946Savg} 755318946Savg 756318946Savgint 757318946Savgabd_iterate_func(abd_t *abd, size_t off, size_t size, 758318946Savg abd_iter_func_t *func, void *private) 759318946Savg{ 760318946Savg int ret = 0; 761318946Savg struct abd_iter aiter; 762318946Savg 763318946Savg abd_verify(abd); 764318946Savg ASSERT3U(off + size, <=, abd->abd_size); 765318946Savg 766318946Savg abd_iter_init(&aiter, abd); 767318946Savg abd_iter_advance(&aiter, off); 768318946Savg 769318946Savg while (size > 0) { 770318946Savg abd_iter_map(&aiter); 771318946Savg 772318946Savg size_t len = MIN(aiter.iter_mapsize, size); 773318946Savg ASSERT3U(len, >, 0); 774318946Savg 775318946Savg ret = func(aiter.iter_mapaddr, len, private); 776318946Savg 777318946Savg abd_iter_unmap(&aiter); 778318946Savg 779318946Savg if (ret != 0) 780318946Savg break; 781318946Savg 782318946Savg size -= len; 783318946Savg abd_iter_advance(&aiter, len); 784318946Savg } 785318946Savg 786318946Savg return (ret); 787318946Savg} 788318946Savg 789318946Savgstruct buf_arg { 790318946Savg void *arg_buf; 791318946Savg}; 792318946Savg 793318946Savgstatic int 794318946Savgabd_copy_to_buf_off_cb(void *buf, size_t size, void *private) 795318946Savg{ 796318946Savg struct buf_arg *ba_ptr = private; 797318946Savg 798318946Savg (void) memcpy(ba_ptr->arg_buf, buf, size); 799318946Savg ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; 800318946Savg 801318946Savg return (0); 802318946Savg} 803318946Savg 804318946Savg/* 805318946Savg * Copy abd to buf. (off is the offset in abd.) 806318946Savg */ 807318946Savgvoid 808318946Savgabd_copy_to_buf_off(void *buf, abd_t *abd, size_t off, size_t size) 809318946Savg{ 810318946Savg struct buf_arg ba_ptr = { buf }; 811318946Savg 812318946Savg (void) abd_iterate_func(abd, off, size, abd_copy_to_buf_off_cb, 813318946Savg &ba_ptr); 814318946Savg} 815318946Savg 816318946Savgstatic int 817318946Savgabd_cmp_buf_off_cb(void *buf, size_t size, void *private) 818318946Savg{ 819318946Savg int ret; 820318946Savg struct buf_arg *ba_ptr = private; 821318946Savg 822318946Savg ret = memcmp(buf, ba_ptr->arg_buf, size); 823318946Savg ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; 824318946Savg 825318946Savg return (ret); 826318946Savg} 827318946Savg 828318946Savg/* 829318946Savg * Compare the contents of abd to buf. (off is the offset in abd.) 830318946Savg */ 831318946Savgint 832318946Savgabd_cmp_buf_off(abd_t *abd, const void *buf, size_t off, size_t size) 833318946Savg{ 834318946Savg struct buf_arg ba_ptr = { (void *) buf }; 835318946Savg 836318946Savg return (abd_iterate_func(abd, off, size, abd_cmp_buf_off_cb, &ba_ptr)); 837318946Savg} 838318946Savg 839318946Savgstatic int 840318946Savgabd_copy_from_buf_off_cb(void *buf, size_t size, void *private) 841318946Savg{ 842318946Savg struct buf_arg *ba_ptr = private; 843318946Savg 844318946Savg (void) memcpy(buf, ba_ptr->arg_buf, size); 845318946Savg ba_ptr->arg_buf = (char *)ba_ptr->arg_buf + size; 846318946Savg 847318946Savg return (0); 848318946Savg} 849318946Savg 850318946Savg/* 851318946Savg * Copy from buf to abd. (off is the offset in abd.) 852318946Savg */ 853318946Savgvoid 854318946Savgabd_copy_from_buf_off(abd_t *abd, const void *buf, size_t off, size_t size) 855318946Savg{ 856318946Savg struct buf_arg ba_ptr = { (void *) buf }; 857318946Savg 858318946Savg (void) abd_iterate_func(abd, off, size, abd_copy_from_buf_off_cb, 859318946Savg &ba_ptr); 860318946Savg} 861318946Savg 862318946Savg/*ARGSUSED*/ 863318946Savgstatic int 864318946Savgabd_zero_off_cb(void *buf, size_t size, void *private) 865318946Savg{ 866318946Savg (void) memset(buf, 0, size); 867318946Savg return (0); 868318946Savg} 869318946Savg 870318946Savg/* 871318946Savg * Zero out the abd from a particular offset to the end. 872318946Savg */ 873318946Savgvoid 874318946Savgabd_zero_off(abd_t *abd, size_t off, size_t size) 875318946Savg{ 876318946Savg (void) abd_iterate_func(abd, off, size, abd_zero_off_cb, NULL); 877318946Savg} 878318946Savg 879318946Savg/* 880318946Savg * Iterate over two ABDs and call func incrementally on the two ABDs' data in 881318946Savg * equal-sized chunks (passed to func as raw buffers). func could be called many 882318946Savg * times during this iteration. 883318946Savg */ 884318946Savgint 885318946Savgabd_iterate_func2(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, 886318946Savg size_t size, abd_iter_func2_t *func, void *private) 887318946Savg{ 888318946Savg int ret = 0; 889318946Savg struct abd_iter daiter, saiter; 890318946Savg 891318946Savg abd_verify(dabd); 892318946Savg abd_verify(sabd); 893318946Savg 894318946Savg ASSERT3U(doff + size, <=, dabd->abd_size); 895318946Savg ASSERT3U(soff + size, <=, sabd->abd_size); 896318946Savg 897318946Savg abd_iter_init(&daiter, dabd); 898318946Savg abd_iter_init(&saiter, sabd); 899318946Savg abd_iter_advance(&daiter, doff); 900318946Savg abd_iter_advance(&saiter, soff); 901318946Savg 902318946Savg while (size > 0) { 903318946Savg abd_iter_map(&daiter); 904318946Savg abd_iter_map(&saiter); 905318946Savg 906318946Savg size_t dlen = MIN(daiter.iter_mapsize, size); 907318946Savg size_t slen = MIN(saiter.iter_mapsize, size); 908318946Savg size_t len = MIN(dlen, slen); 909318946Savg ASSERT(dlen > 0 || slen > 0); 910318946Savg 911318946Savg ret = func(daiter.iter_mapaddr, saiter.iter_mapaddr, len, 912318946Savg private); 913318946Savg 914318946Savg abd_iter_unmap(&saiter); 915318946Savg abd_iter_unmap(&daiter); 916318946Savg 917318946Savg if (ret != 0) 918318946Savg break; 919318946Savg 920318946Savg size -= len; 921318946Savg abd_iter_advance(&daiter, len); 922318946Savg abd_iter_advance(&saiter, len); 923318946Savg } 924318946Savg 925318946Savg return (ret); 926318946Savg} 927318946Savg 928318946Savg/*ARGSUSED*/ 929318946Savgstatic int 930318946Savgabd_copy_off_cb(void *dbuf, void *sbuf, size_t size, void *private) 931318946Savg{ 932318946Savg (void) memcpy(dbuf, sbuf, size); 933318946Savg return (0); 934318946Savg} 935318946Savg 936318946Savg/* 937318946Savg * Copy from sabd to dabd starting from soff and doff. 938318946Savg */ 939318946Savgvoid 940318946Savgabd_copy_off(abd_t *dabd, abd_t *sabd, size_t doff, size_t soff, size_t size) 941318946Savg{ 942318946Savg (void) abd_iterate_func2(dabd, sabd, doff, soff, size, 943318946Savg abd_copy_off_cb, NULL); 944318946Savg} 945318946Savg 946318946Savg/*ARGSUSED*/ 947318946Savgstatic int 948318946Savgabd_cmp_cb(void *bufa, void *bufb, size_t size, void *private) 949318946Savg{ 950318946Savg return (memcmp(bufa, bufb, size)); 951318946Savg} 952318946Savg 953318946Savg/* 954318946Savg * Compares the first size bytes of two ABDs. 955318946Savg */ 956318946Savgint 957318946Savgabd_cmp(abd_t *dabd, abd_t *sabd, size_t size) 958318946Savg{ 959318946Savg return (abd_iterate_func2(dabd, sabd, 0, 0, size, abd_cmp_cb, NULL)); 960318946Savg} 961