subr_sglist.c revision 277759
1193260Sjhb/*- 2193260Sjhb * Copyright (c) 2008 Yahoo!, Inc. 3193260Sjhb * All rights reserved. 4193260Sjhb * Written by: John Baldwin <jhb@FreeBSD.org> 5193260Sjhb * 6193260Sjhb * Redistribution and use in source and binary forms, with or without 7193260Sjhb * modification, are permitted provided that the following conditions 8193260Sjhb * are met: 9193260Sjhb * 1. Redistributions of source code must retain the above copyright 10193260Sjhb * notice, this list of conditions and the following disclaimer. 11193260Sjhb * 2. Redistributions in binary form must reproduce the above copyright 12193260Sjhb * notice, this list of conditions and the following disclaimer in the 13193260Sjhb * documentation and/or other materials provided with the distribution. 14193260Sjhb * 3. Neither the name of the author nor the names of any co-contributors 15193260Sjhb * may be used to endorse or promote products derived from this software 16193260Sjhb * without specific prior written permission. 17193260Sjhb * 18193260Sjhb * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19193260Sjhb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20193260Sjhb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21193260Sjhb * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22193260Sjhb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23193260Sjhb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24193260Sjhb * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25193260Sjhb * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26193260Sjhb * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27193260Sjhb * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28193260Sjhb * SUCH DAMAGE. 29193260Sjhb */ 30193260Sjhb 31193260Sjhb#include <sys/cdefs.h> 32193260Sjhb__FBSDID("$FreeBSD: head/sys/kern/subr_sglist.c 277759 2015-01-26 16:26:28Z jhb $"); 33193260Sjhb 34193260Sjhb#include <sys/param.h> 35193260Sjhb#include <sys/kernel.h> 36260581Sbryanv#include <sys/bio.h> 37193260Sjhb#include <sys/malloc.h> 38193260Sjhb#include <sys/mbuf.h> 39193260Sjhb#include <sys/proc.h> 40193260Sjhb#include <sys/sglist.h> 41193260Sjhb#include <sys/uio.h> 42193260Sjhb 43193260Sjhb#include <vm/vm.h> 44260581Sbryanv#include <vm/vm_page.h> 45193260Sjhb#include <vm/pmap.h> 46193260Sjhb#include <vm/vm_map.h> 47193260Sjhb 48193260Sjhb#include <sys/ktr.h> 49193260Sjhb 50193260Sjhbstatic MALLOC_DEFINE(M_SGLIST, "sglist", "scatter/gather lists"); 51193260Sjhb 52193260Sjhb/* 53196417Sjhb * Convenience macros to save the state of an sglist so it can be restored 54196417Sjhb * if an append attempt fails. Since sglist's only grow we only need to 55196417Sjhb * save the current count of segments and the length of the ending segment. 56196417Sjhb * Earlier segments will not be changed by an append, and the only change 57196417Sjhb * that can occur to the ending segment is that it can be extended. 58196417Sjhb */ 59196417Sjhbstruct sgsave { 60196417Sjhb u_short sg_nseg; 61196417Sjhb size_t ss_len; 62196417Sjhb}; 63196417Sjhb 64196417Sjhb#define SGLIST_SAVE(sg, sgsave) do { \ 65196417Sjhb (sgsave).sg_nseg = (sg)->sg_nseg; \ 66196417Sjhb if ((sgsave).sg_nseg > 0) \ 67196417Sjhb (sgsave).ss_len = (sg)->sg_segs[(sgsave).sg_nseg - 1].ss_len; \ 68196417Sjhb else \ 69196417Sjhb (sgsave).ss_len = 0; \ 70196417Sjhb} while (0) 71196417Sjhb 72196417Sjhb#define SGLIST_RESTORE(sg, sgsave) do { \ 73196417Sjhb (sg)->sg_nseg = (sgsave).sg_nseg; \ 74196417Sjhb if ((sgsave).sg_nseg > 0) \ 75196417Sjhb (sg)->sg_segs[(sgsave).sg_nseg - 1].ss_len = (sgsave).ss_len; \ 76196417Sjhb} while (0) 77196417Sjhb 78196417Sjhb/* 79193260Sjhb * Append a single (paddr, len) to a sglist. sg is the list and ss is 80193260Sjhb * the current segment in the list. If we run out of segments then 81193260Sjhb * EFBIG will be returned. 82193260Sjhb */ 83193260Sjhbstatic __inline int 84193260Sjhb_sglist_append_range(struct sglist *sg, struct sglist_seg **ssp, 85193260Sjhb vm_paddr_t paddr, size_t len) 86193260Sjhb{ 87193260Sjhb struct sglist_seg *ss; 88193260Sjhb 89193260Sjhb ss = *ssp; 90193260Sjhb if (ss->ss_paddr + ss->ss_len == paddr) 91193260Sjhb ss->ss_len += len; 92193260Sjhb else { 93196417Sjhb if (sg->sg_nseg == sg->sg_maxseg) 94193260Sjhb return (EFBIG); 95193260Sjhb ss++; 96193260Sjhb ss->ss_paddr = paddr; 97193260Sjhb ss->ss_len = len; 98193260Sjhb sg->sg_nseg++; 99193260Sjhb *ssp = ss; 100193260Sjhb } 101193260Sjhb return (0); 102193260Sjhb} 103193260Sjhb 104193260Sjhb/* 105193260Sjhb * Worker routine to append a virtual address range (either kernel or 106193260Sjhb * user) to a scatter/gather list. 107193260Sjhb */ 108193260Sjhbstatic __inline int 109193260Sjhb_sglist_append_buf(struct sglist *sg, void *buf, size_t len, pmap_t pmap, 110193260Sjhb size_t *donep) 111193260Sjhb{ 112193260Sjhb struct sglist_seg *ss; 113193260Sjhb vm_offset_t vaddr, offset; 114193260Sjhb vm_paddr_t paddr; 115193260Sjhb size_t seglen; 116193260Sjhb int error; 117193260Sjhb 118193260Sjhb if (donep) 119193260Sjhb *donep = 0; 120193260Sjhb if (len == 0) 121193260Sjhb return (0); 122193260Sjhb 123193260Sjhb /* Do the first page. It may have an offset. */ 124193260Sjhb vaddr = (vm_offset_t)buf; 125193260Sjhb offset = vaddr & PAGE_MASK; 126193260Sjhb if (pmap != NULL) 127193260Sjhb paddr = pmap_extract(pmap, vaddr); 128193260Sjhb else 129193260Sjhb paddr = pmap_kextract(vaddr); 130193260Sjhb seglen = MIN(len, PAGE_SIZE - offset); 131193260Sjhb if (sg->sg_nseg == 0) { 132193260Sjhb ss = sg->sg_segs; 133193260Sjhb ss->ss_paddr = paddr; 134193260Sjhb ss->ss_len = seglen; 135193260Sjhb sg->sg_nseg = 1; 136193260Sjhb } else { 137193260Sjhb ss = &sg->sg_segs[sg->sg_nseg - 1]; 138193260Sjhb error = _sglist_append_range(sg, &ss, paddr, seglen); 139196417Sjhb if (error) 140196417Sjhb return (error); 141193260Sjhb } 142196417Sjhb vaddr += seglen; 143196417Sjhb len -= seglen; 144196417Sjhb if (donep) 145196417Sjhb *donep += seglen; 146193260Sjhb 147196417Sjhb while (len > 0) { 148193260Sjhb seglen = MIN(len, PAGE_SIZE); 149193260Sjhb if (pmap != NULL) 150193260Sjhb paddr = pmap_extract(pmap, vaddr); 151193260Sjhb else 152193260Sjhb paddr = pmap_kextract(vaddr); 153193260Sjhb error = _sglist_append_range(sg, &ss, paddr, seglen); 154196417Sjhb if (error) 155196417Sjhb return (error); 156196417Sjhb vaddr += seglen; 157196417Sjhb len -= seglen; 158196417Sjhb if (donep) 159196417Sjhb *donep += seglen; 160193260Sjhb } 161193260Sjhb 162196417Sjhb return (0); 163193260Sjhb} 164193260Sjhb 165193260Sjhb/* 166193260Sjhb * Determine the number of scatter/gather list elements needed to 167193260Sjhb * describe a kernel virtual address range. 168193260Sjhb */ 169193260Sjhbint 170193260Sjhbsglist_count(void *buf, size_t len) 171193260Sjhb{ 172193260Sjhb vm_offset_t vaddr, vendaddr; 173193260Sjhb vm_paddr_t lastaddr, paddr; 174193260Sjhb int nsegs; 175193260Sjhb 176193260Sjhb if (len == 0) 177193260Sjhb return (0); 178193260Sjhb 179193260Sjhb vaddr = trunc_page((vm_offset_t)buf); 180193260Sjhb vendaddr = (vm_offset_t)buf + len; 181193260Sjhb nsegs = 1; 182193260Sjhb lastaddr = pmap_kextract(vaddr); 183193260Sjhb vaddr += PAGE_SIZE; 184193260Sjhb while (vaddr < vendaddr) { 185193260Sjhb paddr = pmap_kextract(vaddr); 186193260Sjhb if (lastaddr + PAGE_SIZE != paddr) 187193260Sjhb nsegs++; 188193260Sjhb lastaddr = paddr; 189193260Sjhb vaddr += PAGE_SIZE; 190193260Sjhb } 191193260Sjhb return (nsegs); 192193260Sjhb} 193193260Sjhb 194193260Sjhb/* 195193260Sjhb * Allocate a scatter/gather list along with 'nsegs' segments. The 196193260Sjhb * 'mflags' parameters are the same as passed to malloc(9). The caller 197193260Sjhb * should use sglist_free() to free this list. 198193260Sjhb */ 199193260Sjhbstruct sglist * 200193260Sjhbsglist_alloc(int nsegs, int mflags) 201193260Sjhb{ 202193260Sjhb struct sglist *sg; 203193260Sjhb 204193260Sjhb sg = malloc(sizeof(struct sglist) + nsegs * sizeof(struct sglist_seg), 205193260Sjhb M_SGLIST, mflags); 206193260Sjhb if (sg == NULL) 207193260Sjhb return (NULL); 208193260Sjhb sglist_init(sg, nsegs, (struct sglist_seg *)(sg + 1)); 209193260Sjhb return (sg); 210193260Sjhb} 211193260Sjhb 212193260Sjhb/* 213193260Sjhb * Free a scatter/gather list allocated via sglist_allc(). 214193260Sjhb */ 215193260Sjhbvoid 216193260Sjhbsglist_free(struct sglist *sg) 217193260Sjhb{ 218193260Sjhb 219277759Sjhb if (sg == NULL) 220277759Sjhb return; 221277759Sjhb 222193260Sjhb if (refcount_release(&sg->sg_refs)) 223193260Sjhb free(sg, M_SGLIST); 224193260Sjhb} 225193260Sjhb 226193260Sjhb/* 227193260Sjhb * Append the segments to describe a single kernel virtual address 228193260Sjhb * range to a scatter/gather list. If there are insufficient 229193260Sjhb * segments, then this fails with EFBIG. 230193260Sjhb */ 231193260Sjhbint 232193260Sjhbsglist_append(struct sglist *sg, void *buf, size_t len) 233193260Sjhb{ 234196417Sjhb struct sgsave save; 235196417Sjhb int error; 236193260Sjhb 237193260Sjhb if (sg->sg_maxseg == 0) 238193260Sjhb return (EINVAL); 239196417Sjhb SGLIST_SAVE(sg, save); 240196417Sjhb error = _sglist_append_buf(sg, buf, len, NULL, NULL); 241196417Sjhb if (error) 242196417Sjhb SGLIST_RESTORE(sg, save); 243196417Sjhb return (error); 244193260Sjhb} 245193260Sjhb 246193260Sjhb/* 247260581Sbryanv * Append the segments to describe a bio's data to a scatter/gather list. 248260581Sbryanv * If there are insufficient segments, then this fails with EFBIG. 249260581Sbryanv * 250260581Sbryanv * NOTE: This function expects bio_bcount to be initialized. 251260581Sbryanv */ 252260581Sbryanvint 253260581Sbryanvsglist_append_bio(struct sglist *sg, struct bio *bp) 254260581Sbryanv{ 255260581Sbryanv struct sgsave save; 256260581Sbryanv vm_paddr_t paddr; 257260581Sbryanv size_t len, tlen; 258260581Sbryanv int error, i, ma_offs; 259260581Sbryanv 260260581Sbryanv if ((bp->bio_flags & BIO_UNMAPPED) == 0) { 261260581Sbryanv error = sglist_append(sg, bp->bio_data, bp->bio_bcount); 262260581Sbryanv return (error); 263260581Sbryanv } 264260581Sbryanv 265260581Sbryanv if (sg->sg_maxseg == 0) 266260581Sbryanv return (EINVAL); 267260581Sbryanv 268260581Sbryanv SGLIST_SAVE(sg, save); 269260581Sbryanv tlen = bp->bio_bcount; 270260581Sbryanv ma_offs = bp->bio_ma_offset; 271260581Sbryanv for (i = 0; tlen > 0; i++, tlen -= len) { 272260581Sbryanv len = min(PAGE_SIZE - ma_offs, tlen); 273260581Sbryanv paddr = VM_PAGE_TO_PHYS(bp->bio_ma[i]) + ma_offs; 274260581Sbryanv error = sglist_append_phys(sg, paddr, len); 275260581Sbryanv if (error) { 276260581Sbryanv SGLIST_RESTORE(sg, save); 277260581Sbryanv return (error); 278260581Sbryanv } 279260581Sbryanv ma_offs = 0; 280260581Sbryanv } 281260581Sbryanv return (0); 282260581Sbryanv} 283260581Sbryanv 284260581Sbryanv/* 285193260Sjhb * Append a single physical address range to a scatter/gather list. 286193260Sjhb * If there are insufficient segments, then this fails with EFBIG. 287193260Sjhb */ 288193260Sjhbint 289193260Sjhbsglist_append_phys(struct sglist *sg, vm_paddr_t paddr, size_t len) 290193260Sjhb{ 291193260Sjhb struct sglist_seg *ss; 292196417Sjhb struct sgsave save; 293196417Sjhb int error; 294193260Sjhb 295193260Sjhb if (sg->sg_maxseg == 0) 296193260Sjhb return (EINVAL); 297193260Sjhb if (len == 0) 298193260Sjhb return (0); 299193260Sjhb 300193260Sjhb if (sg->sg_nseg == 0) { 301193260Sjhb sg->sg_segs[0].ss_paddr = paddr; 302193260Sjhb sg->sg_segs[0].ss_len = len; 303193260Sjhb sg->sg_nseg = 1; 304193260Sjhb return (0); 305193260Sjhb } 306193260Sjhb ss = &sg->sg_segs[sg->sg_nseg - 1]; 307196417Sjhb SGLIST_SAVE(sg, save); 308196417Sjhb error = _sglist_append_range(sg, &ss, paddr, len); 309196417Sjhb if (error) 310196417Sjhb SGLIST_RESTORE(sg, save); 311196417Sjhb return (error); 312193260Sjhb} 313193260Sjhb 314193260Sjhb/* 315193260Sjhb * Append the segments that describe a single mbuf chain to a 316193260Sjhb * scatter/gather list. If there are insufficient segments, then this 317193260Sjhb * fails with EFBIG. 318193260Sjhb */ 319193260Sjhbint 320193260Sjhbsglist_append_mbuf(struct sglist *sg, struct mbuf *m0) 321193260Sjhb{ 322196417Sjhb struct sgsave save; 323193260Sjhb struct mbuf *m; 324193260Sjhb int error; 325193260Sjhb 326193260Sjhb if (sg->sg_maxseg == 0) 327193260Sjhb return (EINVAL); 328193260Sjhb 329193260Sjhb error = 0; 330196417Sjhb SGLIST_SAVE(sg, save); 331193260Sjhb for (m = m0; m != NULL; m = m->m_next) { 332193260Sjhb if (m->m_len > 0) { 333193260Sjhb error = sglist_append(sg, m->m_data, m->m_len); 334196417Sjhb if (error) { 335196417Sjhb SGLIST_RESTORE(sg, save); 336193260Sjhb return (error); 337196417Sjhb } 338193260Sjhb } 339193260Sjhb } 340193260Sjhb return (0); 341193260Sjhb} 342193260Sjhb 343193260Sjhb/* 344193260Sjhb * Append the segments that describe a single user address range to a 345193260Sjhb * scatter/gather list. If there are insufficient segments, then this 346193260Sjhb * fails with EFBIG. 347193260Sjhb */ 348193260Sjhbint 349193260Sjhbsglist_append_user(struct sglist *sg, void *buf, size_t len, struct thread *td) 350193260Sjhb{ 351196417Sjhb struct sgsave save; 352196417Sjhb int error; 353193260Sjhb 354193260Sjhb if (sg->sg_maxseg == 0) 355193260Sjhb return (EINVAL); 356196417Sjhb SGLIST_SAVE(sg, save); 357196417Sjhb error = _sglist_append_buf(sg, buf, len, 358196417Sjhb vmspace_pmap(td->td_proc->p_vmspace), NULL); 359196417Sjhb if (error) 360196417Sjhb SGLIST_RESTORE(sg, save); 361196417Sjhb return (error); 362193260Sjhb} 363193260Sjhb 364193260Sjhb/* 365193260Sjhb * Append the segments that describe a single uio to a scatter/gather 366193260Sjhb * list. If there are insufficient segments, then this fails with 367193260Sjhb * EFBIG. 368193260Sjhb */ 369193260Sjhbint 370193260Sjhbsglist_append_uio(struct sglist *sg, struct uio *uio) 371193260Sjhb{ 372193260Sjhb struct iovec *iov; 373196417Sjhb struct sgsave save; 374193260Sjhb size_t resid, minlen; 375193260Sjhb pmap_t pmap; 376193260Sjhb int error, i; 377193260Sjhb 378193260Sjhb if (sg->sg_maxseg == 0) 379193260Sjhb return (EINVAL); 380193260Sjhb 381193260Sjhb resid = uio->uio_resid; 382193260Sjhb iov = uio->uio_iov; 383193260Sjhb 384193260Sjhb if (uio->uio_segflg == UIO_USERSPACE) { 385193260Sjhb KASSERT(uio->uio_td != NULL, 386193260Sjhb ("sglist_append_uio: USERSPACE but no thread")); 387193260Sjhb pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace); 388193260Sjhb } else 389193260Sjhb pmap = NULL; 390193260Sjhb 391193260Sjhb error = 0; 392196417Sjhb SGLIST_SAVE(sg, save); 393193260Sjhb for (i = 0; i < uio->uio_iovcnt && resid != 0; i++) { 394193260Sjhb /* 395193260Sjhb * Now at the first iovec to load. Load each iovec 396193260Sjhb * until we have exhausted the residual count. 397193260Sjhb */ 398193260Sjhb minlen = MIN(resid, iov[i].iov_len); 399193260Sjhb if (minlen > 0) { 400193260Sjhb error = _sglist_append_buf(sg, iov[i].iov_base, minlen, 401193260Sjhb pmap, NULL); 402196417Sjhb if (error) { 403196417Sjhb SGLIST_RESTORE(sg, save); 404193260Sjhb return (error); 405196417Sjhb } 406193260Sjhb resid -= minlen; 407193260Sjhb } 408193260Sjhb } 409193260Sjhb return (0); 410193260Sjhb} 411193260Sjhb 412193260Sjhb/* 413193260Sjhb * Append the segments that describe at most 'resid' bytes from a 414193260Sjhb * single uio to a scatter/gather list. If there are insufficient 415193260Sjhb * segments, then only the amount that fits is appended. 416193260Sjhb */ 417193260Sjhbint 418196404Sjhbsglist_consume_uio(struct sglist *sg, struct uio *uio, size_t resid) 419193260Sjhb{ 420193260Sjhb struct iovec *iov; 421193260Sjhb size_t done; 422193260Sjhb pmap_t pmap; 423193260Sjhb int error, len; 424193260Sjhb 425193260Sjhb if (sg->sg_maxseg == 0) 426193260Sjhb return (EINVAL); 427193260Sjhb 428193260Sjhb if (uio->uio_segflg == UIO_USERSPACE) { 429193260Sjhb KASSERT(uio->uio_td != NULL, 430193260Sjhb ("sglist_consume_uio: USERSPACE but no thread")); 431193260Sjhb pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace); 432193260Sjhb } else 433193260Sjhb pmap = NULL; 434193260Sjhb 435193260Sjhb error = 0; 436193260Sjhb while (resid > 0 && uio->uio_resid) { 437193260Sjhb iov = uio->uio_iov; 438193260Sjhb len = iov->iov_len; 439193260Sjhb if (len == 0) { 440193260Sjhb uio->uio_iov++; 441193260Sjhb uio->uio_iovcnt--; 442193260Sjhb continue; 443193260Sjhb } 444193260Sjhb if (len > resid) 445193260Sjhb len = resid; 446193260Sjhb 447193260Sjhb /* 448193260Sjhb * Try to append this iovec. If we run out of room, 449193260Sjhb * then break out of the loop. 450193260Sjhb */ 451193260Sjhb error = _sglist_append_buf(sg, iov->iov_base, len, pmap, &done); 452193260Sjhb iov->iov_base = (char *)iov->iov_base + done; 453193260Sjhb iov->iov_len -= done; 454193260Sjhb uio->uio_resid -= done; 455193260Sjhb uio->uio_offset += done; 456193260Sjhb resid -= done; 457193260Sjhb if (error) 458193260Sjhb break; 459193260Sjhb } 460193260Sjhb return (0); 461193260Sjhb} 462193260Sjhb 463193260Sjhb/* 464193260Sjhb * Allocate and populate a scatter/gather list to describe a single 465193260Sjhb * kernel virtual address range. 466193260Sjhb */ 467193260Sjhbstruct sglist * 468193260Sjhbsglist_build(void *buf, size_t len, int mflags) 469193260Sjhb{ 470193260Sjhb struct sglist *sg; 471193260Sjhb int nsegs; 472193260Sjhb 473193260Sjhb if (len == 0) 474193260Sjhb return (NULL); 475193260Sjhb 476193260Sjhb nsegs = sglist_count(buf, len); 477193260Sjhb sg = sglist_alloc(nsegs, mflags); 478193260Sjhb if (sg == NULL) 479193260Sjhb return (NULL); 480193260Sjhb if (sglist_append(sg, buf, len) != 0) { 481193260Sjhb sglist_free(sg); 482193260Sjhb return (NULL); 483193260Sjhb } 484193260Sjhb return (sg); 485193260Sjhb} 486193260Sjhb 487193260Sjhb/* 488193260Sjhb * Clone a new copy of a scatter/gather list. 489193260Sjhb */ 490193260Sjhbstruct sglist * 491193260Sjhbsglist_clone(struct sglist *sg, int mflags) 492193260Sjhb{ 493193260Sjhb struct sglist *new; 494193260Sjhb 495193260Sjhb if (sg == NULL) 496193260Sjhb return (NULL); 497193260Sjhb new = sglist_alloc(sg->sg_maxseg, mflags); 498193260Sjhb if (new == NULL) 499193260Sjhb return (NULL); 500196417Sjhb new->sg_nseg = sg->sg_nseg; 501193260Sjhb bcopy(sg->sg_segs, new->sg_segs, sizeof(struct sglist_seg) * 502193260Sjhb sg->sg_nseg); 503193260Sjhb return (new); 504193260Sjhb} 505193260Sjhb 506193260Sjhb/* 507193260Sjhb * Calculate the total length of the segments described in a 508193260Sjhb * scatter/gather list. 509193260Sjhb */ 510193260Sjhbsize_t 511193260Sjhbsglist_length(struct sglist *sg) 512193260Sjhb{ 513193260Sjhb size_t space; 514193260Sjhb int i; 515193260Sjhb 516193260Sjhb space = 0; 517193260Sjhb for (i = 0; i < sg->sg_nseg; i++) 518193260Sjhb space += sg->sg_segs[i].ss_len; 519193260Sjhb return (space); 520193260Sjhb} 521193260Sjhb 522193260Sjhb/* 523193260Sjhb * Split a scatter/gather list into two lists. The scatter/gather 524193260Sjhb * entries for the first 'length' bytes of the 'original' list are 525193260Sjhb * stored in the '*head' list and are removed from 'original'. 526193260Sjhb * 527193260Sjhb * If '*head' is NULL, then a new list will be allocated using 528193260Sjhb * 'mflags'. If M_NOWAIT is specified and the allocation fails, 529193260Sjhb * ENOMEM will be returned. 530193260Sjhb * 531193260Sjhb * If '*head' is not NULL, it should point to an empty sglist. If it 532193260Sjhb * does not have enough room for the remaining space, then EFBIG will 533193260Sjhb * be returned. If '*head' is not empty, then EINVAL will be 534193260Sjhb * returned. 535193260Sjhb * 536193260Sjhb * If 'original' is shared (refcount > 1), then EDOOFUS will be 537193260Sjhb * returned. 538193260Sjhb */ 539193260Sjhbint 540193260Sjhbsglist_split(struct sglist *original, struct sglist **head, size_t length, 541193260Sjhb int mflags) 542193260Sjhb{ 543193260Sjhb struct sglist *sg; 544193260Sjhb size_t space, split; 545193260Sjhb int count, i; 546193260Sjhb 547193260Sjhb if (original->sg_refs > 1) 548193260Sjhb return (EDOOFUS); 549193260Sjhb 550193260Sjhb /* Figure out how big of a sglist '*head' has to hold. */ 551193260Sjhb count = 0; 552193260Sjhb space = 0; 553193260Sjhb split = 0; 554193260Sjhb for (i = 0; i < original->sg_nseg; i++) { 555193260Sjhb space += original->sg_segs[i].ss_len; 556193260Sjhb count++; 557193260Sjhb if (space >= length) { 558193260Sjhb /* 559193260Sjhb * If 'length' falls in the middle of a 560193260Sjhb * scatter/gather list entry, then 'split' 561193260Sjhb * holds how much of that entry will remain in 562193260Sjhb * 'original'. 563193260Sjhb */ 564193260Sjhb split = space - length; 565193260Sjhb break; 566193260Sjhb } 567193260Sjhb } 568193260Sjhb 569193260Sjhb /* Nothing to do, so leave head empty. */ 570193260Sjhb if (count == 0) 571193260Sjhb return (0); 572193260Sjhb 573193260Sjhb if (*head == NULL) { 574193260Sjhb sg = sglist_alloc(count, mflags); 575193260Sjhb if (sg == NULL) 576193260Sjhb return (ENOMEM); 577193260Sjhb *head = sg; 578193260Sjhb } else { 579193260Sjhb sg = *head; 580193260Sjhb if (sg->sg_maxseg < count) 581193260Sjhb return (EFBIG); 582193260Sjhb if (sg->sg_nseg != 0) 583193260Sjhb return (EINVAL); 584193260Sjhb } 585193260Sjhb 586193260Sjhb /* Copy 'count' entries to 'sg' from 'original'. */ 587193260Sjhb bcopy(original->sg_segs, sg->sg_segs, count * 588193260Sjhb sizeof(struct sglist_seg)); 589193260Sjhb sg->sg_nseg = count; 590193260Sjhb 591193260Sjhb /* 592193260Sjhb * If we had to split a list entry, fixup the last entry in 593193260Sjhb * 'sg' and the new first entry in 'original'. We also 594193260Sjhb * decrement 'count' by 1 since we will only be removing 595193260Sjhb * 'count - 1' segments from 'original' now. 596193260Sjhb */ 597193260Sjhb if (split != 0) { 598193260Sjhb count--; 599193260Sjhb sg->sg_segs[count].ss_len -= split; 600193260Sjhb original->sg_segs[count].ss_paddr = 601193260Sjhb sg->sg_segs[count].ss_paddr + split; 602193260Sjhb original->sg_segs[count].ss_len = split; 603193260Sjhb } 604193260Sjhb 605193260Sjhb /* Trim 'count' entries from the front of 'original'. */ 606193260Sjhb original->sg_nseg -= count; 607193260Sjhb bcopy(original->sg_segs + count, original->sg_segs, count * 608193260Sjhb sizeof(struct sglist_seg)); 609193260Sjhb return (0); 610193260Sjhb} 611193260Sjhb 612193260Sjhb/* 613193260Sjhb * Append the scatter/gather list elements in 'second' to the 614193260Sjhb * scatter/gather list 'first'. If there is not enough space in 615193260Sjhb * 'first', EFBIG is returned. 616193260Sjhb */ 617193260Sjhbint 618193260Sjhbsglist_join(struct sglist *first, struct sglist *second) 619193260Sjhb{ 620193260Sjhb struct sglist_seg *flast, *sfirst; 621193260Sjhb int append; 622193260Sjhb 623193260Sjhb /* If 'second' is empty, there is nothing to do. */ 624193260Sjhb if (second->sg_nseg == 0) 625193260Sjhb return (0); 626193260Sjhb 627193260Sjhb /* 628193260Sjhb * If the first entry in 'second' can be appended to the last entry 629193260Sjhb * in 'first' then set append to '1'. 630193260Sjhb */ 631193260Sjhb append = 0; 632193260Sjhb flast = &first->sg_segs[first->sg_nseg - 1]; 633193260Sjhb sfirst = &second->sg_segs[0]; 634193260Sjhb if (first->sg_nseg != 0 && 635193260Sjhb flast->ss_paddr + flast->ss_len == sfirst->ss_paddr) 636193260Sjhb append = 1; 637193260Sjhb 638193260Sjhb /* Make sure 'first' has enough room. */ 639193260Sjhb if (first->sg_nseg + second->sg_nseg - append > first->sg_maxseg) 640193260Sjhb return (EFBIG); 641193260Sjhb 642193260Sjhb /* Merge last in 'first' and first in 'second' if needed. */ 643193260Sjhb if (append) 644193260Sjhb flast->ss_len += sfirst->ss_len; 645193260Sjhb 646193260Sjhb /* Append new segments from 'second' to 'first'. */ 647193260Sjhb bcopy(first->sg_segs + first->sg_nseg, second->sg_segs + append, 648193260Sjhb (second->sg_nseg - append) * sizeof(struct sglist_seg)); 649193260Sjhb first->sg_nseg += second->sg_nseg - append; 650193260Sjhb sglist_reset(second); 651193260Sjhb return (0); 652193260Sjhb} 653193260Sjhb 654193260Sjhb/* 655193260Sjhb * Generate a new scatter/gather list from a range of an existing 656193260Sjhb * scatter/gather list. The 'offset' and 'length' parameters specify 657193260Sjhb * the logical range of the 'original' list to extract. If that range 658193260Sjhb * is not a subset of the length of 'original', then EINVAL is 659193260Sjhb * returned. The new scatter/gather list is stored in '*slice'. 660193260Sjhb * 661193260Sjhb * If '*slice' is NULL, then a new list will be allocated using 662193260Sjhb * 'mflags'. If M_NOWAIT is specified and the allocation fails, 663193260Sjhb * ENOMEM will be returned. 664193260Sjhb * 665193260Sjhb * If '*slice' is not NULL, it should point to an empty sglist. If it 666193260Sjhb * does not have enough room for the remaining space, then EFBIG will 667193260Sjhb * be returned. If '*slice' is not empty, then EINVAL will be 668193260Sjhb * returned. 669193260Sjhb */ 670193260Sjhbint 671193260Sjhbsglist_slice(struct sglist *original, struct sglist **slice, size_t offset, 672193260Sjhb size_t length, int mflags) 673193260Sjhb{ 674193260Sjhb struct sglist *sg; 675193260Sjhb size_t space, end, foffs, loffs; 676193260Sjhb int count, i, fseg; 677193260Sjhb 678193260Sjhb /* Nothing to do. */ 679193260Sjhb if (length == 0) 680193260Sjhb return (0); 681193260Sjhb 682193260Sjhb /* Figure out how many segments '*slice' needs to have. */ 683193260Sjhb end = offset + length; 684193260Sjhb space = 0; 685193260Sjhb count = 0; 686193260Sjhb fseg = 0; 687193260Sjhb foffs = loffs = 0; 688193260Sjhb for (i = 0; i < original->sg_nseg; i++) { 689193260Sjhb space += original->sg_segs[i].ss_len; 690193260Sjhb if (space > offset) { 691193260Sjhb /* 692193260Sjhb * When we hit the first segment, store its index 693193260Sjhb * in 'fseg' and the offset into the first segment 694193260Sjhb * of 'offset' in 'foffs'. 695193260Sjhb */ 696193260Sjhb if (count == 0) { 697193260Sjhb fseg = i; 698193260Sjhb foffs = offset - (space - 699193260Sjhb original->sg_segs[i].ss_len); 700193260Sjhb CTR1(KTR_DEV, "sglist_slice: foffs = %08lx", 701193260Sjhb foffs); 702193260Sjhb } 703193260Sjhb count++; 704193260Sjhb 705193260Sjhb /* 706193260Sjhb * When we hit the last segment, break out of 707193260Sjhb * the loop. Store the amount of extra space 708193260Sjhb * at the end of this segment in 'loffs'. 709193260Sjhb */ 710193260Sjhb if (space >= end) { 711193260Sjhb loffs = space - end; 712193260Sjhb CTR1(KTR_DEV, "sglist_slice: loffs = %08lx", 713193260Sjhb loffs); 714193260Sjhb break; 715193260Sjhb } 716193260Sjhb } 717193260Sjhb } 718193260Sjhb 719193260Sjhb /* If we never hit 'end', then 'length' ran off the end, so fail. */ 720193260Sjhb if (space < end) 721193260Sjhb return (EINVAL); 722193260Sjhb 723193260Sjhb if (*slice == NULL) { 724193260Sjhb sg = sglist_alloc(count, mflags); 725193260Sjhb if (sg == NULL) 726193260Sjhb return (ENOMEM); 727193260Sjhb *slice = sg; 728193260Sjhb } else { 729193260Sjhb sg = *slice; 730193260Sjhb if (sg->sg_maxseg < count) 731193260Sjhb return (EFBIG); 732193260Sjhb if (sg->sg_nseg != 0) 733193260Sjhb return (EINVAL); 734193260Sjhb } 735193260Sjhb 736193260Sjhb /* 737193260Sjhb * Copy over 'count' segments from 'original' starting at 738193260Sjhb * 'fseg' to 'sg'. 739193260Sjhb */ 740193260Sjhb bcopy(original->sg_segs + fseg, sg->sg_segs, 741193260Sjhb count * sizeof(struct sglist_seg)); 742193260Sjhb sg->sg_nseg = count; 743193260Sjhb 744193260Sjhb /* Fixup first and last segments if needed. */ 745193260Sjhb if (foffs != 0) { 746193260Sjhb sg->sg_segs[0].ss_paddr += foffs; 747193260Sjhb sg->sg_segs[0].ss_len -= foffs; 748193260Sjhb CTR2(KTR_DEV, "sglist_slice seg[0]: %08lx:%08lx", 749193260Sjhb (long)sg->sg_segs[0].ss_paddr, sg->sg_segs[0].ss_len); 750193260Sjhb } 751193260Sjhb if (loffs != 0) { 752193260Sjhb sg->sg_segs[count - 1].ss_len -= loffs; 753193260Sjhb CTR2(KTR_DEV, "sglist_slice seg[%d]: len %08x", count - 1, 754193260Sjhb sg->sg_segs[count - 1].ss_len); 755193260Sjhb } 756193260Sjhb return (0); 757193260Sjhb} 758