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: releng/10.3/sys/kern/subr_sglist.c 260856 2014-01-18 18:36:41Z bryanv $"); 33193260Sjhb 34193260Sjhb#include <sys/param.h> 35193260Sjhb#include <sys/kernel.h> 36260856Sbryanv#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> 44260856Sbryanv#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 219193260Sjhb if (refcount_release(&sg->sg_refs)) 220193260Sjhb free(sg, M_SGLIST); 221193260Sjhb} 222193260Sjhb 223193260Sjhb/* 224193260Sjhb * Append the segments to describe a single kernel virtual address 225193260Sjhb * range to a scatter/gather list. If there are insufficient 226193260Sjhb * segments, then this fails with EFBIG. 227193260Sjhb */ 228193260Sjhbint 229193260Sjhbsglist_append(struct sglist *sg, void *buf, size_t len) 230193260Sjhb{ 231196417Sjhb struct sgsave save; 232196417Sjhb int error; 233193260Sjhb 234193260Sjhb if (sg->sg_maxseg == 0) 235193260Sjhb return (EINVAL); 236196417Sjhb SGLIST_SAVE(sg, save); 237196417Sjhb error = _sglist_append_buf(sg, buf, len, NULL, NULL); 238196417Sjhb if (error) 239196417Sjhb SGLIST_RESTORE(sg, save); 240196417Sjhb return (error); 241193260Sjhb} 242193260Sjhb 243193260Sjhb/* 244260856Sbryanv * Append the segments to describe a bio's data to a scatter/gather list. 245260856Sbryanv * If there are insufficient segments, then this fails with EFBIG. 246260856Sbryanv * 247260856Sbryanv * NOTE: This function expects bio_bcount to be initialized. 248260856Sbryanv */ 249260856Sbryanvint 250260856Sbryanvsglist_append_bio(struct sglist *sg, struct bio *bp) 251260856Sbryanv{ 252260856Sbryanv struct sgsave save; 253260856Sbryanv vm_paddr_t paddr; 254260856Sbryanv size_t len, tlen; 255260856Sbryanv int error, i, ma_offs; 256260856Sbryanv 257260856Sbryanv if ((bp->bio_flags & BIO_UNMAPPED) == 0) { 258260856Sbryanv error = sglist_append(sg, bp->bio_data, bp->bio_bcount); 259260856Sbryanv return (error); 260260856Sbryanv } 261260856Sbryanv 262260856Sbryanv if (sg->sg_maxseg == 0) 263260856Sbryanv return (EINVAL); 264260856Sbryanv 265260856Sbryanv SGLIST_SAVE(sg, save); 266260856Sbryanv tlen = bp->bio_bcount; 267260856Sbryanv ma_offs = bp->bio_ma_offset; 268260856Sbryanv for (i = 0; tlen > 0; i++, tlen -= len) { 269260856Sbryanv len = min(PAGE_SIZE - ma_offs, tlen); 270260856Sbryanv paddr = VM_PAGE_TO_PHYS(bp->bio_ma[i]) + ma_offs; 271260856Sbryanv error = sglist_append_phys(sg, paddr, len); 272260856Sbryanv if (error) { 273260856Sbryanv SGLIST_RESTORE(sg, save); 274260856Sbryanv return (error); 275260856Sbryanv } 276260856Sbryanv ma_offs = 0; 277260856Sbryanv } 278260856Sbryanv return (0); 279260856Sbryanv} 280260856Sbryanv 281260856Sbryanv/* 282193260Sjhb * Append a single physical address range to a scatter/gather list. 283193260Sjhb * If there are insufficient segments, then this fails with EFBIG. 284193260Sjhb */ 285193260Sjhbint 286193260Sjhbsglist_append_phys(struct sglist *sg, vm_paddr_t paddr, size_t len) 287193260Sjhb{ 288193260Sjhb struct sglist_seg *ss; 289196417Sjhb struct sgsave save; 290196417Sjhb int error; 291193260Sjhb 292193260Sjhb if (sg->sg_maxseg == 0) 293193260Sjhb return (EINVAL); 294193260Sjhb if (len == 0) 295193260Sjhb return (0); 296193260Sjhb 297193260Sjhb if (sg->sg_nseg == 0) { 298193260Sjhb sg->sg_segs[0].ss_paddr = paddr; 299193260Sjhb sg->sg_segs[0].ss_len = len; 300193260Sjhb sg->sg_nseg = 1; 301193260Sjhb return (0); 302193260Sjhb } 303193260Sjhb ss = &sg->sg_segs[sg->sg_nseg - 1]; 304196417Sjhb SGLIST_SAVE(sg, save); 305196417Sjhb error = _sglist_append_range(sg, &ss, paddr, len); 306196417Sjhb if (error) 307196417Sjhb SGLIST_RESTORE(sg, save); 308196417Sjhb return (error); 309193260Sjhb} 310193260Sjhb 311193260Sjhb/* 312193260Sjhb * Append the segments that describe a single mbuf chain to a 313193260Sjhb * scatter/gather list. If there are insufficient segments, then this 314193260Sjhb * fails with EFBIG. 315193260Sjhb */ 316193260Sjhbint 317193260Sjhbsglist_append_mbuf(struct sglist *sg, struct mbuf *m0) 318193260Sjhb{ 319196417Sjhb struct sgsave save; 320193260Sjhb struct mbuf *m; 321193260Sjhb int error; 322193260Sjhb 323193260Sjhb if (sg->sg_maxseg == 0) 324193260Sjhb return (EINVAL); 325193260Sjhb 326193260Sjhb error = 0; 327196417Sjhb SGLIST_SAVE(sg, save); 328193260Sjhb for (m = m0; m != NULL; m = m->m_next) { 329193260Sjhb if (m->m_len > 0) { 330193260Sjhb error = sglist_append(sg, m->m_data, m->m_len); 331196417Sjhb if (error) { 332196417Sjhb SGLIST_RESTORE(sg, save); 333193260Sjhb return (error); 334196417Sjhb } 335193260Sjhb } 336193260Sjhb } 337193260Sjhb return (0); 338193260Sjhb} 339193260Sjhb 340193260Sjhb/* 341193260Sjhb * Append the segments that describe a single user address range to a 342193260Sjhb * scatter/gather list. If there are insufficient segments, then this 343193260Sjhb * fails with EFBIG. 344193260Sjhb */ 345193260Sjhbint 346193260Sjhbsglist_append_user(struct sglist *sg, void *buf, size_t len, struct thread *td) 347193260Sjhb{ 348196417Sjhb struct sgsave save; 349196417Sjhb int error; 350193260Sjhb 351193260Sjhb if (sg->sg_maxseg == 0) 352193260Sjhb return (EINVAL); 353196417Sjhb SGLIST_SAVE(sg, save); 354196417Sjhb error = _sglist_append_buf(sg, buf, len, 355196417Sjhb vmspace_pmap(td->td_proc->p_vmspace), NULL); 356196417Sjhb if (error) 357196417Sjhb SGLIST_RESTORE(sg, save); 358196417Sjhb return (error); 359193260Sjhb} 360193260Sjhb 361193260Sjhb/* 362193260Sjhb * Append the segments that describe a single uio to a scatter/gather 363193260Sjhb * list. If there are insufficient segments, then this fails with 364193260Sjhb * EFBIG. 365193260Sjhb */ 366193260Sjhbint 367193260Sjhbsglist_append_uio(struct sglist *sg, struct uio *uio) 368193260Sjhb{ 369193260Sjhb struct iovec *iov; 370196417Sjhb struct sgsave save; 371193260Sjhb size_t resid, minlen; 372193260Sjhb pmap_t pmap; 373193260Sjhb int error, i; 374193260Sjhb 375193260Sjhb if (sg->sg_maxseg == 0) 376193260Sjhb return (EINVAL); 377193260Sjhb 378193260Sjhb resid = uio->uio_resid; 379193260Sjhb iov = uio->uio_iov; 380193260Sjhb 381193260Sjhb if (uio->uio_segflg == UIO_USERSPACE) { 382193260Sjhb KASSERT(uio->uio_td != NULL, 383193260Sjhb ("sglist_append_uio: USERSPACE but no thread")); 384193260Sjhb pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace); 385193260Sjhb } else 386193260Sjhb pmap = NULL; 387193260Sjhb 388193260Sjhb error = 0; 389196417Sjhb SGLIST_SAVE(sg, save); 390193260Sjhb for (i = 0; i < uio->uio_iovcnt && resid != 0; i++) { 391193260Sjhb /* 392193260Sjhb * Now at the first iovec to load. Load each iovec 393193260Sjhb * until we have exhausted the residual count. 394193260Sjhb */ 395193260Sjhb minlen = MIN(resid, iov[i].iov_len); 396193260Sjhb if (minlen > 0) { 397193260Sjhb error = _sglist_append_buf(sg, iov[i].iov_base, minlen, 398193260Sjhb pmap, NULL); 399196417Sjhb if (error) { 400196417Sjhb SGLIST_RESTORE(sg, save); 401193260Sjhb return (error); 402196417Sjhb } 403193260Sjhb resid -= minlen; 404193260Sjhb } 405193260Sjhb } 406193260Sjhb return (0); 407193260Sjhb} 408193260Sjhb 409193260Sjhb/* 410193260Sjhb * Append the segments that describe at most 'resid' bytes from a 411193260Sjhb * single uio to a scatter/gather list. If there are insufficient 412193260Sjhb * segments, then only the amount that fits is appended. 413193260Sjhb */ 414193260Sjhbint 415196404Sjhbsglist_consume_uio(struct sglist *sg, struct uio *uio, size_t resid) 416193260Sjhb{ 417193260Sjhb struct iovec *iov; 418193260Sjhb size_t done; 419193260Sjhb pmap_t pmap; 420193260Sjhb int error, len; 421193260Sjhb 422193260Sjhb if (sg->sg_maxseg == 0) 423193260Sjhb return (EINVAL); 424193260Sjhb 425193260Sjhb if (uio->uio_segflg == UIO_USERSPACE) { 426193260Sjhb KASSERT(uio->uio_td != NULL, 427193260Sjhb ("sglist_consume_uio: USERSPACE but no thread")); 428193260Sjhb pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace); 429193260Sjhb } else 430193260Sjhb pmap = NULL; 431193260Sjhb 432193260Sjhb error = 0; 433193260Sjhb while (resid > 0 && uio->uio_resid) { 434193260Sjhb iov = uio->uio_iov; 435193260Sjhb len = iov->iov_len; 436193260Sjhb if (len == 0) { 437193260Sjhb uio->uio_iov++; 438193260Sjhb uio->uio_iovcnt--; 439193260Sjhb continue; 440193260Sjhb } 441193260Sjhb if (len > resid) 442193260Sjhb len = resid; 443193260Sjhb 444193260Sjhb /* 445193260Sjhb * Try to append this iovec. If we run out of room, 446193260Sjhb * then break out of the loop. 447193260Sjhb */ 448193260Sjhb error = _sglist_append_buf(sg, iov->iov_base, len, pmap, &done); 449193260Sjhb iov->iov_base = (char *)iov->iov_base + done; 450193260Sjhb iov->iov_len -= done; 451193260Sjhb uio->uio_resid -= done; 452193260Sjhb uio->uio_offset += done; 453193260Sjhb resid -= done; 454193260Sjhb if (error) 455193260Sjhb break; 456193260Sjhb } 457193260Sjhb return (0); 458193260Sjhb} 459193260Sjhb 460193260Sjhb/* 461193260Sjhb * Allocate and populate a scatter/gather list to describe a single 462193260Sjhb * kernel virtual address range. 463193260Sjhb */ 464193260Sjhbstruct sglist * 465193260Sjhbsglist_build(void *buf, size_t len, int mflags) 466193260Sjhb{ 467193260Sjhb struct sglist *sg; 468193260Sjhb int nsegs; 469193260Sjhb 470193260Sjhb if (len == 0) 471193260Sjhb return (NULL); 472193260Sjhb 473193260Sjhb nsegs = sglist_count(buf, len); 474193260Sjhb sg = sglist_alloc(nsegs, mflags); 475193260Sjhb if (sg == NULL) 476193260Sjhb return (NULL); 477193260Sjhb if (sglist_append(sg, buf, len) != 0) { 478193260Sjhb sglist_free(sg); 479193260Sjhb return (NULL); 480193260Sjhb } 481193260Sjhb return (sg); 482193260Sjhb} 483193260Sjhb 484193260Sjhb/* 485193260Sjhb * Clone a new copy of a scatter/gather list. 486193260Sjhb */ 487193260Sjhbstruct sglist * 488193260Sjhbsglist_clone(struct sglist *sg, int mflags) 489193260Sjhb{ 490193260Sjhb struct sglist *new; 491193260Sjhb 492193260Sjhb if (sg == NULL) 493193260Sjhb return (NULL); 494193260Sjhb new = sglist_alloc(sg->sg_maxseg, mflags); 495193260Sjhb if (new == NULL) 496193260Sjhb return (NULL); 497196417Sjhb new->sg_nseg = sg->sg_nseg; 498193260Sjhb bcopy(sg->sg_segs, new->sg_segs, sizeof(struct sglist_seg) * 499193260Sjhb sg->sg_nseg); 500193260Sjhb return (new); 501193260Sjhb} 502193260Sjhb 503193260Sjhb/* 504193260Sjhb * Calculate the total length of the segments described in a 505193260Sjhb * scatter/gather list. 506193260Sjhb */ 507193260Sjhbsize_t 508193260Sjhbsglist_length(struct sglist *sg) 509193260Sjhb{ 510193260Sjhb size_t space; 511193260Sjhb int i; 512193260Sjhb 513193260Sjhb space = 0; 514193260Sjhb for (i = 0; i < sg->sg_nseg; i++) 515193260Sjhb space += sg->sg_segs[i].ss_len; 516193260Sjhb return (space); 517193260Sjhb} 518193260Sjhb 519193260Sjhb/* 520193260Sjhb * Split a scatter/gather list into two lists. The scatter/gather 521193260Sjhb * entries for the first 'length' bytes of the 'original' list are 522193260Sjhb * stored in the '*head' list and are removed from 'original'. 523193260Sjhb * 524193260Sjhb * If '*head' is NULL, then a new list will be allocated using 525193260Sjhb * 'mflags'. If M_NOWAIT is specified and the allocation fails, 526193260Sjhb * ENOMEM will be returned. 527193260Sjhb * 528193260Sjhb * If '*head' is not NULL, it should point to an empty sglist. If it 529193260Sjhb * does not have enough room for the remaining space, then EFBIG will 530193260Sjhb * be returned. If '*head' is not empty, then EINVAL will be 531193260Sjhb * returned. 532193260Sjhb * 533193260Sjhb * If 'original' is shared (refcount > 1), then EDOOFUS will be 534193260Sjhb * returned. 535193260Sjhb */ 536193260Sjhbint 537193260Sjhbsglist_split(struct sglist *original, struct sglist **head, size_t length, 538193260Sjhb int mflags) 539193260Sjhb{ 540193260Sjhb struct sglist *sg; 541193260Sjhb size_t space, split; 542193260Sjhb int count, i; 543193260Sjhb 544193260Sjhb if (original->sg_refs > 1) 545193260Sjhb return (EDOOFUS); 546193260Sjhb 547193260Sjhb /* Figure out how big of a sglist '*head' has to hold. */ 548193260Sjhb count = 0; 549193260Sjhb space = 0; 550193260Sjhb split = 0; 551193260Sjhb for (i = 0; i < original->sg_nseg; i++) { 552193260Sjhb space += original->sg_segs[i].ss_len; 553193260Sjhb count++; 554193260Sjhb if (space >= length) { 555193260Sjhb /* 556193260Sjhb * If 'length' falls in the middle of a 557193260Sjhb * scatter/gather list entry, then 'split' 558193260Sjhb * holds how much of that entry will remain in 559193260Sjhb * 'original'. 560193260Sjhb */ 561193260Sjhb split = space - length; 562193260Sjhb break; 563193260Sjhb } 564193260Sjhb } 565193260Sjhb 566193260Sjhb /* Nothing to do, so leave head empty. */ 567193260Sjhb if (count == 0) 568193260Sjhb return (0); 569193260Sjhb 570193260Sjhb if (*head == NULL) { 571193260Sjhb sg = sglist_alloc(count, mflags); 572193260Sjhb if (sg == NULL) 573193260Sjhb return (ENOMEM); 574193260Sjhb *head = sg; 575193260Sjhb } else { 576193260Sjhb sg = *head; 577193260Sjhb if (sg->sg_maxseg < count) 578193260Sjhb return (EFBIG); 579193260Sjhb if (sg->sg_nseg != 0) 580193260Sjhb return (EINVAL); 581193260Sjhb } 582193260Sjhb 583193260Sjhb /* Copy 'count' entries to 'sg' from 'original'. */ 584193260Sjhb bcopy(original->sg_segs, sg->sg_segs, count * 585193260Sjhb sizeof(struct sglist_seg)); 586193260Sjhb sg->sg_nseg = count; 587193260Sjhb 588193260Sjhb /* 589193260Sjhb * If we had to split a list entry, fixup the last entry in 590193260Sjhb * 'sg' and the new first entry in 'original'. We also 591193260Sjhb * decrement 'count' by 1 since we will only be removing 592193260Sjhb * 'count - 1' segments from 'original' now. 593193260Sjhb */ 594193260Sjhb if (split != 0) { 595193260Sjhb count--; 596193260Sjhb sg->sg_segs[count].ss_len -= split; 597193260Sjhb original->sg_segs[count].ss_paddr = 598193260Sjhb sg->sg_segs[count].ss_paddr + split; 599193260Sjhb original->sg_segs[count].ss_len = split; 600193260Sjhb } 601193260Sjhb 602193260Sjhb /* Trim 'count' entries from the front of 'original'. */ 603193260Sjhb original->sg_nseg -= count; 604193260Sjhb bcopy(original->sg_segs + count, original->sg_segs, count * 605193260Sjhb sizeof(struct sglist_seg)); 606193260Sjhb return (0); 607193260Sjhb} 608193260Sjhb 609193260Sjhb/* 610193260Sjhb * Append the scatter/gather list elements in 'second' to the 611193260Sjhb * scatter/gather list 'first'. If there is not enough space in 612193260Sjhb * 'first', EFBIG is returned. 613193260Sjhb */ 614193260Sjhbint 615193260Sjhbsglist_join(struct sglist *first, struct sglist *second) 616193260Sjhb{ 617193260Sjhb struct sglist_seg *flast, *sfirst; 618193260Sjhb int append; 619193260Sjhb 620193260Sjhb /* If 'second' is empty, there is nothing to do. */ 621193260Sjhb if (second->sg_nseg == 0) 622193260Sjhb return (0); 623193260Sjhb 624193260Sjhb /* 625193260Sjhb * If the first entry in 'second' can be appended to the last entry 626193260Sjhb * in 'first' then set append to '1'. 627193260Sjhb */ 628193260Sjhb append = 0; 629193260Sjhb flast = &first->sg_segs[first->sg_nseg - 1]; 630193260Sjhb sfirst = &second->sg_segs[0]; 631193260Sjhb if (first->sg_nseg != 0 && 632193260Sjhb flast->ss_paddr + flast->ss_len == sfirst->ss_paddr) 633193260Sjhb append = 1; 634193260Sjhb 635193260Sjhb /* Make sure 'first' has enough room. */ 636193260Sjhb if (first->sg_nseg + second->sg_nseg - append > first->sg_maxseg) 637193260Sjhb return (EFBIG); 638193260Sjhb 639193260Sjhb /* Merge last in 'first' and first in 'second' if needed. */ 640193260Sjhb if (append) 641193260Sjhb flast->ss_len += sfirst->ss_len; 642193260Sjhb 643193260Sjhb /* Append new segments from 'second' to 'first'. */ 644193260Sjhb bcopy(first->sg_segs + first->sg_nseg, second->sg_segs + append, 645193260Sjhb (second->sg_nseg - append) * sizeof(struct sglist_seg)); 646193260Sjhb first->sg_nseg += second->sg_nseg - append; 647193260Sjhb sglist_reset(second); 648193260Sjhb return (0); 649193260Sjhb} 650193260Sjhb 651193260Sjhb/* 652193260Sjhb * Generate a new scatter/gather list from a range of an existing 653193260Sjhb * scatter/gather list. The 'offset' and 'length' parameters specify 654193260Sjhb * the logical range of the 'original' list to extract. If that range 655193260Sjhb * is not a subset of the length of 'original', then EINVAL is 656193260Sjhb * returned. The new scatter/gather list is stored in '*slice'. 657193260Sjhb * 658193260Sjhb * If '*slice' is NULL, then a new list will be allocated using 659193260Sjhb * 'mflags'. If M_NOWAIT is specified and the allocation fails, 660193260Sjhb * ENOMEM will be returned. 661193260Sjhb * 662193260Sjhb * If '*slice' is not NULL, it should point to an empty sglist. If it 663193260Sjhb * does not have enough room for the remaining space, then EFBIG will 664193260Sjhb * be returned. If '*slice' is not empty, then EINVAL will be 665193260Sjhb * returned. 666193260Sjhb */ 667193260Sjhbint 668193260Sjhbsglist_slice(struct sglist *original, struct sglist **slice, size_t offset, 669193260Sjhb size_t length, int mflags) 670193260Sjhb{ 671193260Sjhb struct sglist *sg; 672193260Sjhb size_t space, end, foffs, loffs; 673193260Sjhb int count, i, fseg; 674193260Sjhb 675193260Sjhb /* Nothing to do. */ 676193260Sjhb if (length == 0) 677193260Sjhb return (0); 678193260Sjhb 679193260Sjhb /* Figure out how many segments '*slice' needs to have. */ 680193260Sjhb end = offset + length; 681193260Sjhb space = 0; 682193260Sjhb count = 0; 683193260Sjhb fseg = 0; 684193260Sjhb foffs = loffs = 0; 685193260Sjhb for (i = 0; i < original->sg_nseg; i++) { 686193260Sjhb space += original->sg_segs[i].ss_len; 687193260Sjhb if (space > offset) { 688193260Sjhb /* 689193260Sjhb * When we hit the first segment, store its index 690193260Sjhb * in 'fseg' and the offset into the first segment 691193260Sjhb * of 'offset' in 'foffs'. 692193260Sjhb */ 693193260Sjhb if (count == 0) { 694193260Sjhb fseg = i; 695193260Sjhb foffs = offset - (space - 696193260Sjhb original->sg_segs[i].ss_len); 697193260Sjhb CTR1(KTR_DEV, "sglist_slice: foffs = %08lx", 698193260Sjhb foffs); 699193260Sjhb } 700193260Sjhb count++; 701193260Sjhb 702193260Sjhb /* 703193260Sjhb * When we hit the last segment, break out of 704193260Sjhb * the loop. Store the amount of extra space 705193260Sjhb * at the end of this segment in 'loffs'. 706193260Sjhb */ 707193260Sjhb if (space >= end) { 708193260Sjhb loffs = space - end; 709193260Sjhb CTR1(KTR_DEV, "sglist_slice: loffs = %08lx", 710193260Sjhb loffs); 711193260Sjhb break; 712193260Sjhb } 713193260Sjhb } 714193260Sjhb } 715193260Sjhb 716193260Sjhb /* If we never hit 'end', then 'length' ran off the end, so fail. */ 717193260Sjhb if (space < end) 718193260Sjhb return (EINVAL); 719193260Sjhb 720193260Sjhb if (*slice == NULL) { 721193260Sjhb sg = sglist_alloc(count, mflags); 722193260Sjhb if (sg == NULL) 723193260Sjhb return (ENOMEM); 724193260Sjhb *slice = sg; 725193260Sjhb } else { 726193260Sjhb sg = *slice; 727193260Sjhb if (sg->sg_maxseg < count) 728193260Sjhb return (EFBIG); 729193260Sjhb if (sg->sg_nseg != 0) 730193260Sjhb return (EINVAL); 731193260Sjhb } 732193260Sjhb 733193260Sjhb /* 734193260Sjhb * Copy over 'count' segments from 'original' starting at 735193260Sjhb * 'fseg' to 'sg'. 736193260Sjhb */ 737193260Sjhb bcopy(original->sg_segs + fseg, sg->sg_segs, 738193260Sjhb count * sizeof(struct sglist_seg)); 739193260Sjhb sg->sg_nseg = count; 740193260Sjhb 741193260Sjhb /* Fixup first and last segments if needed. */ 742193260Sjhb if (foffs != 0) { 743193260Sjhb sg->sg_segs[0].ss_paddr += foffs; 744193260Sjhb sg->sg_segs[0].ss_len -= foffs; 745193260Sjhb CTR2(KTR_DEV, "sglist_slice seg[0]: %08lx:%08lx", 746193260Sjhb (long)sg->sg_segs[0].ss_paddr, sg->sg_segs[0].ss_len); 747193260Sjhb } 748193260Sjhb if (loffs != 0) { 749193260Sjhb sg->sg_segs[count - 1].ss_len -= loffs; 750193260Sjhb CTR2(KTR_DEV, "sglist_slice seg[%d]: len %08x", count - 1, 751193260Sjhb sg->sg_segs[count - 1].ss_len); 752193260Sjhb } 753193260Sjhb return (0); 754193260Sjhb} 755