10db9299fSJens Axboe /* 20db9299fSJens Axboe * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com> 30db9299fSJens Axboe * 40db9299fSJens Axboe * Scatterlist handling helpers. 50db9299fSJens Axboe * 60db9299fSJens Axboe * This source code is licensed under the GNU General Public License, 70db9299fSJens Axboe * Version 2. See the file COPYING for more details. 80db9299fSJens Axboe */ 90db9299fSJens Axboe #include <linux/module.h> 100db9299fSJens Axboe #include <linux/scatterlist.h> 11b1adaf65SFUJITA Tomonori #include <linux/highmem.h> 120db9299fSJens Axboe 130db9299fSJens Axboe /** 140db9299fSJens Axboe * sg_next - return the next scatterlist entry in a list 150db9299fSJens Axboe * @sg: The current sg entry 160db9299fSJens Axboe * 170db9299fSJens Axboe * Description: 180db9299fSJens Axboe * Usually the next entry will be @sg@ + 1, but if this sg element is part 190db9299fSJens Axboe * of a chained scatterlist, it could jump to the start of a new 200db9299fSJens Axboe * scatterlist array. 210db9299fSJens Axboe * 220db9299fSJens Axboe **/ 230db9299fSJens Axboe struct scatterlist *sg_next(struct scatterlist *sg) 240db9299fSJens Axboe { 250db9299fSJens Axboe #ifdef CONFIG_DEBUG_SG 260db9299fSJens Axboe BUG_ON(sg->sg_magic != SG_MAGIC); 270db9299fSJens Axboe #endif 280db9299fSJens Axboe if (sg_is_last(sg)) 290db9299fSJens Axboe return NULL; 300db9299fSJens Axboe 310db9299fSJens Axboe sg++; 320db9299fSJens Axboe if (unlikely(sg_is_chain(sg))) 330db9299fSJens Axboe sg = sg_chain_ptr(sg); 340db9299fSJens Axboe 350db9299fSJens Axboe return sg; 360db9299fSJens Axboe } 370db9299fSJens Axboe EXPORT_SYMBOL(sg_next); 380db9299fSJens Axboe 390db9299fSJens Axboe /** 400db9299fSJens Axboe * sg_last - return the last scatterlist entry in a list 410db9299fSJens Axboe * @sgl: First entry in the scatterlist 420db9299fSJens Axboe * @nents: Number of entries in the scatterlist 430db9299fSJens Axboe * 440db9299fSJens Axboe * Description: 450db9299fSJens Axboe * Should only be used casually, it (currently) scans the entire list 460db9299fSJens Axboe * to get the last entry. 470db9299fSJens Axboe * 480db9299fSJens Axboe * Note that the @sgl@ pointer passed in need not be the first one, 490db9299fSJens Axboe * the important bit is that @nents@ denotes the number of entries that 500db9299fSJens Axboe * exist from @sgl@. 510db9299fSJens Axboe * 520db9299fSJens Axboe **/ 530db9299fSJens Axboe struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) 540db9299fSJens Axboe { 550db9299fSJens Axboe #ifndef ARCH_HAS_SG_CHAIN 560db9299fSJens Axboe struct scatterlist *ret = &sgl[nents - 1]; 570db9299fSJens Axboe #else 580db9299fSJens Axboe struct scatterlist *sg, *ret = NULL; 590db9299fSJens Axboe unsigned int i; 600db9299fSJens Axboe 610db9299fSJens Axboe for_each_sg(sgl, sg, nents, i) 620db9299fSJens Axboe ret = sg; 630db9299fSJens Axboe 640db9299fSJens Axboe #endif 650db9299fSJens Axboe #ifdef CONFIG_DEBUG_SG 660db9299fSJens Axboe BUG_ON(sgl[0].sg_magic != SG_MAGIC); 670db9299fSJens Axboe BUG_ON(!sg_is_last(ret)); 680db9299fSJens Axboe #endif 690db9299fSJens Axboe return ret; 700db9299fSJens Axboe } 710db9299fSJens Axboe EXPORT_SYMBOL(sg_last); 720db9299fSJens Axboe 730db9299fSJens Axboe /** 740db9299fSJens Axboe * sg_init_table - Initialize SG table 750db9299fSJens Axboe * @sgl: The SG table 760db9299fSJens Axboe * @nents: Number of entries in table 770db9299fSJens Axboe * 780db9299fSJens Axboe * Notes: 790db9299fSJens Axboe * If this is part of a chained sg table, sg_mark_end() should be 800db9299fSJens Axboe * used only on the last table part. 810db9299fSJens Axboe * 820db9299fSJens Axboe **/ 830db9299fSJens Axboe void sg_init_table(struct scatterlist *sgl, unsigned int nents) 840db9299fSJens Axboe { 850db9299fSJens Axboe memset(sgl, 0, sizeof(*sgl) * nents); 860db9299fSJens Axboe #ifdef CONFIG_DEBUG_SG 870db9299fSJens Axboe { 880db9299fSJens Axboe unsigned int i; 890db9299fSJens Axboe for (i = 0; i < nents; i++) 900db9299fSJens Axboe sgl[i].sg_magic = SG_MAGIC; 910db9299fSJens Axboe } 920db9299fSJens Axboe #endif 930db9299fSJens Axboe sg_mark_end(&sgl[nents - 1]); 940db9299fSJens Axboe } 950db9299fSJens Axboe EXPORT_SYMBOL(sg_init_table); 960db9299fSJens Axboe 970db9299fSJens Axboe /** 980db9299fSJens Axboe * sg_init_one - Initialize a single entry sg list 990db9299fSJens Axboe * @sg: SG entry 1000db9299fSJens Axboe * @buf: Virtual address for IO 1010db9299fSJens Axboe * @buflen: IO length 1020db9299fSJens Axboe * 1030db9299fSJens Axboe **/ 1040db9299fSJens Axboe void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) 1050db9299fSJens Axboe { 1060db9299fSJens Axboe sg_init_table(sg, 1); 1070db9299fSJens Axboe sg_set_buf(sg, buf, buflen); 1080db9299fSJens Axboe } 1090db9299fSJens Axboe EXPORT_SYMBOL(sg_init_one); 1100db9299fSJens Axboe 1110db9299fSJens Axboe /* 1120db9299fSJens Axboe * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree 1130db9299fSJens Axboe * helpers. 1140db9299fSJens Axboe */ 1150db9299fSJens Axboe static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) 1160db9299fSJens Axboe { 1170db9299fSJens Axboe if (nents == SG_MAX_SINGLE_ALLOC) 1180db9299fSJens Axboe return (struct scatterlist *) __get_free_page(gfp_mask); 1190db9299fSJens Axboe else 1200db9299fSJens Axboe return kmalloc(nents * sizeof(struct scatterlist), gfp_mask); 1210db9299fSJens Axboe } 1220db9299fSJens Axboe 1230db9299fSJens Axboe static void sg_kfree(struct scatterlist *sg, unsigned int nents) 1240db9299fSJens Axboe { 1250db9299fSJens Axboe if (nents == SG_MAX_SINGLE_ALLOC) 1260db9299fSJens Axboe free_page((unsigned long) sg); 1270db9299fSJens Axboe else 1280db9299fSJens Axboe kfree(sg); 1290db9299fSJens Axboe } 1300db9299fSJens Axboe 1310db9299fSJens Axboe /** 1320db9299fSJens Axboe * __sg_free_table - Free a previously mapped sg table 1330db9299fSJens Axboe * @table: The sg table header to use 1347cedb1f1SJames Bottomley * @max_ents: The maximum number of entries per single scatterlist 1350db9299fSJens Axboe * @free_fn: Free function 1360db9299fSJens Axboe * 1370db9299fSJens Axboe * Description: 1387cedb1f1SJames Bottomley * Free an sg table previously allocated and setup with 1397cedb1f1SJames Bottomley * __sg_alloc_table(). The @max_ents value must be identical to 1407cedb1f1SJames Bottomley * that previously used with __sg_alloc_table(). 1410db9299fSJens Axboe * 1420db9299fSJens Axboe **/ 1437cedb1f1SJames Bottomley void __sg_free_table(struct sg_table *table, unsigned int max_ents, 1447cedb1f1SJames Bottomley sg_free_fn *free_fn) 1450db9299fSJens Axboe { 1460db9299fSJens Axboe struct scatterlist *sgl, *next; 1470db9299fSJens Axboe 1480db9299fSJens Axboe if (unlikely(!table->sgl)) 1490db9299fSJens Axboe return; 1500db9299fSJens Axboe 1510db9299fSJens Axboe sgl = table->sgl; 1520db9299fSJens Axboe while (table->orig_nents) { 1530db9299fSJens Axboe unsigned int alloc_size = table->orig_nents; 1540db9299fSJens Axboe unsigned int sg_size; 1550db9299fSJens Axboe 1560db9299fSJens Axboe /* 1577cedb1f1SJames Bottomley * If we have more than max_ents segments left, 1580db9299fSJens Axboe * then assign 'next' to the sg table after the current one. 1590db9299fSJens Axboe * sg_size is then one less than alloc size, since the last 1600db9299fSJens Axboe * element is the chain pointer. 1610db9299fSJens Axboe */ 1627cedb1f1SJames Bottomley if (alloc_size > max_ents) { 1637cedb1f1SJames Bottomley next = sg_chain_ptr(&sgl[max_ents - 1]); 1647cedb1f1SJames Bottomley alloc_size = max_ents; 1650db9299fSJens Axboe sg_size = alloc_size - 1; 1660db9299fSJens Axboe } else { 1670db9299fSJens Axboe sg_size = alloc_size; 1680db9299fSJens Axboe next = NULL; 1690db9299fSJens Axboe } 1700db9299fSJens Axboe 1710db9299fSJens Axboe table->orig_nents -= sg_size; 1720db9299fSJens Axboe free_fn(sgl, alloc_size); 1730db9299fSJens Axboe sgl = next; 1740db9299fSJens Axboe } 1750db9299fSJens Axboe 1760db9299fSJens Axboe table->sgl = NULL; 1770db9299fSJens Axboe } 1780db9299fSJens Axboe EXPORT_SYMBOL(__sg_free_table); 1790db9299fSJens Axboe 1800db9299fSJens Axboe /** 1810db9299fSJens Axboe * sg_free_table - Free a previously allocated sg table 1820db9299fSJens Axboe * @table: The mapped sg table header 1830db9299fSJens Axboe * 1840db9299fSJens Axboe **/ 1850db9299fSJens Axboe void sg_free_table(struct sg_table *table) 1860db9299fSJens Axboe { 1877cedb1f1SJames Bottomley __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree); 1880db9299fSJens Axboe } 1890db9299fSJens Axboe EXPORT_SYMBOL(sg_free_table); 1900db9299fSJens Axboe 1910db9299fSJens Axboe /** 1920db9299fSJens Axboe * __sg_alloc_table - Allocate and initialize an sg table with given allocator 1930db9299fSJens Axboe * @table: The sg table header to use 1940db9299fSJens Axboe * @nents: Number of entries in sg list 1957cedb1f1SJames Bottomley * @max_ents: The maximum number of entries the allocator returns per call 1960db9299fSJens Axboe * @gfp_mask: GFP allocation mask 1970db9299fSJens Axboe * @alloc_fn: Allocator to use 1980db9299fSJens Axboe * 1997cedb1f1SJames Bottomley * Description: 2007cedb1f1SJames Bottomley * This function returns a @table @nents long. The allocator is 2017cedb1f1SJames Bottomley * defined to return scatterlist chunks of maximum size @max_ents. 2027cedb1f1SJames Bottomley * Thus if @nents is bigger than @max_ents, the scatterlists will be 2037cedb1f1SJames Bottomley * chained in units of @max_ents. 2047cedb1f1SJames Bottomley * 2050db9299fSJens Axboe * Notes: 2060db9299fSJens Axboe * If this function returns non-0 (eg failure), the caller must call 2070db9299fSJens Axboe * __sg_free_table() to cleanup any leftover allocations. 2080db9299fSJens Axboe * 2090db9299fSJens Axboe **/ 2107cedb1f1SJames Bottomley int __sg_alloc_table(struct sg_table *table, unsigned int nents, 2117cedb1f1SJames Bottomley unsigned int max_ents, gfp_t gfp_mask, 2120db9299fSJens Axboe sg_alloc_fn *alloc_fn) 2130db9299fSJens Axboe { 2140db9299fSJens Axboe struct scatterlist *sg, *prv; 2150db9299fSJens Axboe unsigned int left; 2160db9299fSJens Axboe 2170db9299fSJens Axboe #ifndef ARCH_HAS_SG_CHAIN 2187cedb1f1SJames Bottomley BUG_ON(nents > max_ents); 2190db9299fSJens Axboe #endif 2200db9299fSJens Axboe 2210db9299fSJens Axboe memset(table, 0, sizeof(*table)); 2220db9299fSJens Axboe 2230db9299fSJens Axboe left = nents; 2240db9299fSJens Axboe prv = NULL; 2250db9299fSJens Axboe do { 2260db9299fSJens Axboe unsigned int sg_size, alloc_size = left; 2270db9299fSJens Axboe 2287cedb1f1SJames Bottomley if (alloc_size > max_ents) { 2297cedb1f1SJames Bottomley alloc_size = max_ents; 2300db9299fSJens Axboe sg_size = alloc_size - 1; 2310db9299fSJens Axboe } else 2320db9299fSJens Axboe sg_size = alloc_size; 2330db9299fSJens Axboe 2340db9299fSJens Axboe left -= sg_size; 2350db9299fSJens Axboe 2360db9299fSJens Axboe sg = alloc_fn(alloc_size, gfp_mask); 2370db9299fSJens Axboe if (unlikely(!sg)) 2380db9299fSJens Axboe return -ENOMEM; 2390db9299fSJens Axboe 2400db9299fSJens Axboe sg_init_table(sg, alloc_size); 2410db9299fSJens Axboe table->nents = table->orig_nents += sg_size; 2420db9299fSJens Axboe 2430db9299fSJens Axboe /* 2440db9299fSJens Axboe * If this is the first mapping, assign the sg table header. 2450db9299fSJens Axboe * If this is not the first mapping, chain previous part. 2460db9299fSJens Axboe */ 2470db9299fSJens Axboe if (prv) 2487cedb1f1SJames Bottomley sg_chain(prv, max_ents, sg); 2490db9299fSJens Axboe else 2500db9299fSJens Axboe table->sgl = sg; 2510db9299fSJens Axboe 2520db9299fSJens Axboe /* 2530db9299fSJens Axboe * If no more entries after this one, mark the end 2540db9299fSJens Axboe */ 2550db9299fSJens Axboe if (!left) 2560db9299fSJens Axboe sg_mark_end(&sg[sg_size - 1]); 2570db9299fSJens Axboe 2580db9299fSJens Axboe /* 2590db9299fSJens Axboe * only really needed for mempool backed sg allocations (like 2600db9299fSJens Axboe * SCSI), a possible improvement here would be to pass the 2610db9299fSJens Axboe * table pointer into the allocator and let that clear these 2620db9299fSJens Axboe * flags 2630db9299fSJens Axboe */ 2640db9299fSJens Axboe gfp_mask &= ~__GFP_WAIT; 2650db9299fSJens Axboe gfp_mask |= __GFP_HIGH; 2660db9299fSJens Axboe prv = sg; 2670db9299fSJens Axboe } while (left); 2680db9299fSJens Axboe 2690db9299fSJens Axboe return 0; 2700db9299fSJens Axboe } 2710db9299fSJens Axboe EXPORT_SYMBOL(__sg_alloc_table); 2720db9299fSJens Axboe 2730db9299fSJens Axboe /** 2740db9299fSJens Axboe * sg_alloc_table - Allocate and initialize an sg table 2750db9299fSJens Axboe * @table: The sg table header to use 2760db9299fSJens Axboe * @nents: Number of entries in sg list 2770db9299fSJens Axboe * @gfp_mask: GFP allocation mask 2780db9299fSJens Axboe * 2790db9299fSJens Axboe * Description: 2800db9299fSJens Axboe * Allocate and initialize an sg table. If @nents@ is larger than 2810db9299fSJens Axboe * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 2820db9299fSJens Axboe * 2830db9299fSJens Axboe **/ 2840db9299fSJens Axboe int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 2850db9299fSJens Axboe { 2860db9299fSJens Axboe int ret; 2870db9299fSJens Axboe 2887cedb1f1SJames Bottomley ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 2897cedb1f1SJames Bottomley gfp_mask, sg_kmalloc); 2900db9299fSJens Axboe if (unlikely(ret)) 2917cedb1f1SJames Bottomley __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree); 2920db9299fSJens Axboe 2930db9299fSJens Axboe return ret; 2940db9299fSJens Axboe } 2950db9299fSJens Axboe EXPORT_SYMBOL(sg_alloc_table); 296b1adaf65SFUJITA Tomonori 297b1adaf65SFUJITA Tomonori /** 298137d3edbSTejun Heo * sg_miter_start - start mapping iteration over a sg list 299137d3edbSTejun Heo * @miter: sg mapping iter to be started 300137d3edbSTejun Heo * @sgl: sg list to iterate over 301137d3edbSTejun Heo * @nents: number of sg entries 302137d3edbSTejun Heo * 303137d3edbSTejun Heo * Description: 304137d3edbSTejun Heo * Starts mapping iterator @miter. 305137d3edbSTejun Heo * 306137d3edbSTejun Heo * Context: 307137d3edbSTejun Heo * Don't care. 308137d3edbSTejun Heo */ 309137d3edbSTejun Heo void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, 310137d3edbSTejun Heo unsigned int nents, unsigned int flags) 311137d3edbSTejun Heo { 312137d3edbSTejun Heo memset(miter, 0, sizeof(struct sg_mapping_iter)); 313137d3edbSTejun Heo 314137d3edbSTejun Heo miter->__sg = sgl; 315137d3edbSTejun Heo miter->__nents = nents; 316137d3edbSTejun Heo miter->__offset = 0; 317137d3edbSTejun Heo miter->__flags = flags; 318137d3edbSTejun Heo } 319137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_start); 320137d3edbSTejun Heo 321137d3edbSTejun Heo /** 322137d3edbSTejun Heo * sg_miter_next - proceed mapping iterator to the next mapping 323137d3edbSTejun Heo * @miter: sg mapping iter to proceed 324137d3edbSTejun Heo * 325137d3edbSTejun Heo * Description: 326137d3edbSTejun Heo * Proceeds @miter@ to the next mapping. @miter@ should have been 327137d3edbSTejun Heo * started using sg_miter_start(). On successful return, 328137d3edbSTejun Heo * @miter@->page, @miter@->addr and @miter@->length point to the 329137d3edbSTejun Heo * current mapping. 330137d3edbSTejun Heo * 331137d3edbSTejun Heo * Context: 332137d3edbSTejun Heo * IRQ disabled if SG_MITER_ATOMIC. IRQ must stay disabled till 333137d3edbSTejun Heo * @miter@ is stopped. May sleep if !SG_MITER_ATOMIC. 334137d3edbSTejun Heo * 335137d3edbSTejun Heo * Returns: 336137d3edbSTejun Heo * true if @miter contains the next mapping. false if end of sg 337137d3edbSTejun Heo * list is reached. 338137d3edbSTejun Heo */ 339137d3edbSTejun Heo bool sg_miter_next(struct sg_mapping_iter *miter) 340137d3edbSTejun Heo { 341137d3edbSTejun Heo unsigned int off, len; 342137d3edbSTejun Heo 343137d3edbSTejun Heo /* check for end and drop resources from the last iteration */ 344137d3edbSTejun Heo if (!miter->__nents) 345137d3edbSTejun Heo return false; 346137d3edbSTejun Heo 347137d3edbSTejun Heo sg_miter_stop(miter); 348137d3edbSTejun Heo 349137d3edbSTejun Heo /* get to the next sg if necessary. __offset is adjusted by stop */ 350137d3edbSTejun Heo if (miter->__offset == miter->__sg->length && --miter->__nents) { 351137d3edbSTejun Heo miter->__sg = sg_next(miter->__sg); 352137d3edbSTejun Heo miter->__offset = 0; 353137d3edbSTejun Heo } 354137d3edbSTejun Heo 355137d3edbSTejun Heo /* map the next page */ 356137d3edbSTejun Heo off = miter->__sg->offset + miter->__offset; 357137d3edbSTejun Heo len = miter->__sg->length - miter->__offset; 358137d3edbSTejun Heo 359137d3edbSTejun Heo miter->page = nth_page(sg_page(miter->__sg), off >> PAGE_SHIFT); 360137d3edbSTejun Heo off &= ~PAGE_MASK; 361137d3edbSTejun Heo miter->length = min_t(unsigned int, len, PAGE_SIZE - off); 362137d3edbSTejun Heo miter->consumed = miter->length; 363137d3edbSTejun Heo 364137d3edbSTejun Heo if (miter->__flags & SG_MITER_ATOMIC) 365137d3edbSTejun Heo miter->addr = kmap_atomic(miter->page, KM_BIO_SRC_IRQ) + off; 366137d3edbSTejun Heo else 367137d3edbSTejun Heo miter->addr = kmap(miter->page) + off; 368137d3edbSTejun Heo 369137d3edbSTejun Heo return true; 370137d3edbSTejun Heo } 371137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_next); 372137d3edbSTejun Heo 373137d3edbSTejun Heo /** 374137d3edbSTejun Heo * sg_miter_stop - stop mapping iteration 375137d3edbSTejun Heo * @miter: sg mapping iter to be stopped 376137d3edbSTejun Heo * 377137d3edbSTejun Heo * Description: 378137d3edbSTejun Heo * Stops mapping iterator @miter. @miter should have been started 379137d3edbSTejun Heo * started using sg_miter_start(). A stopped iteration can be 380137d3edbSTejun Heo * resumed by calling sg_miter_next() on it. This is useful when 381137d3edbSTejun Heo * resources (kmap) need to be released during iteration. 382137d3edbSTejun Heo * 383137d3edbSTejun Heo * Context: 384137d3edbSTejun Heo * IRQ disabled if the SG_MITER_ATOMIC is set. Don't care otherwise. 385137d3edbSTejun Heo */ 386137d3edbSTejun Heo void sg_miter_stop(struct sg_mapping_iter *miter) 387137d3edbSTejun Heo { 388137d3edbSTejun Heo WARN_ON(miter->consumed > miter->length); 389137d3edbSTejun Heo 390137d3edbSTejun Heo /* drop resources from the last iteration */ 391137d3edbSTejun Heo if (miter->addr) { 392137d3edbSTejun Heo miter->__offset += miter->consumed; 393137d3edbSTejun Heo 394137d3edbSTejun Heo if (miter->__flags & SG_MITER_ATOMIC) { 395137d3edbSTejun Heo WARN_ON(!irqs_disabled()); 396137d3edbSTejun Heo kunmap_atomic(miter->addr, KM_BIO_SRC_IRQ); 397137d3edbSTejun Heo } else 398f652c521SArjan van de Ven kunmap(miter->page); 399137d3edbSTejun Heo 400137d3edbSTejun Heo miter->page = NULL; 401137d3edbSTejun Heo miter->addr = NULL; 402137d3edbSTejun Heo miter->length = 0; 403137d3edbSTejun Heo miter->consumed = 0; 404137d3edbSTejun Heo } 405137d3edbSTejun Heo } 406137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_stop); 407137d3edbSTejun Heo 408137d3edbSTejun Heo /** 409b1adaf65SFUJITA Tomonori * sg_copy_buffer - Copy data between a linear buffer and an SG list 410b1adaf65SFUJITA Tomonori * @sgl: The SG list 411b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 412b1adaf65SFUJITA Tomonori * @buf: Where to copy from 413b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 414b1adaf65SFUJITA Tomonori * @to_buffer: transfer direction (non zero == from an sg list to a 415b1adaf65SFUJITA Tomonori * buffer, 0 == from a buffer to an sg list 416b1adaf65SFUJITA Tomonori * 417b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 418b1adaf65SFUJITA Tomonori * 419b1adaf65SFUJITA Tomonori **/ 420b1adaf65SFUJITA Tomonori static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, 421b1adaf65SFUJITA Tomonori void *buf, size_t buflen, int to_buffer) 422b1adaf65SFUJITA Tomonori { 423137d3edbSTejun Heo unsigned int offset = 0; 424137d3edbSTejun Heo struct sg_mapping_iter miter; 42550bed2e2SFUJITA Tomonori unsigned long flags; 426b1adaf65SFUJITA Tomonori 427137d3edbSTejun Heo sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC); 428b1adaf65SFUJITA Tomonori 42950bed2e2SFUJITA Tomonori local_irq_save(flags); 43050bed2e2SFUJITA Tomonori 431137d3edbSTejun Heo while (sg_miter_next(&miter) && offset < buflen) { 432137d3edbSTejun Heo unsigned int len; 433b1adaf65SFUJITA Tomonori 434137d3edbSTejun Heo len = min(miter.length, buflen - offset); 435b1adaf65SFUJITA Tomonori 436b1adaf65SFUJITA Tomonori if (to_buffer) 437137d3edbSTejun Heo memcpy(buf + offset, miter.addr, len); 438b1adaf65SFUJITA Tomonori else { 439137d3edbSTejun Heo memcpy(miter.addr, buf + offset, len); 440137d3edbSTejun Heo flush_kernel_dcache_page(miter.page); 441b1adaf65SFUJITA Tomonori } 442b1adaf65SFUJITA Tomonori 443137d3edbSTejun Heo offset += len; 444b1adaf65SFUJITA Tomonori } 445b1adaf65SFUJITA Tomonori 446137d3edbSTejun Heo sg_miter_stop(&miter); 447b1adaf65SFUJITA Tomonori 44850bed2e2SFUJITA Tomonori local_irq_restore(flags); 449137d3edbSTejun Heo return offset; 450b1adaf65SFUJITA Tomonori } 451b1adaf65SFUJITA Tomonori 452b1adaf65SFUJITA Tomonori /** 453b1adaf65SFUJITA Tomonori * sg_copy_from_buffer - Copy from a linear buffer to an SG list 454b1adaf65SFUJITA Tomonori * @sgl: The SG list 455b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 456b1adaf65SFUJITA Tomonori * @buf: Where to copy from 457b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 458b1adaf65SFUJITA Tomonori * 459b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 460b1adaf65SFUJITA Tomonori * 461b1adaf65SFUJITA Tomonori **/ 462b1adaf65SFUJITA Tomonori size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, 463b1adaf65SFUJITA Tomonori void *buf, size_t buflen) 464b1adaf65SFUJITA Tomonori { 465b1adaf65SFUJITA Tomonori return sg_copy_buffer(sgl, nents, buf, buflen, 0); 466b1adaf65SFUJITA Tomonori } 467b1adaf65SFUJITA Tomonori EXPORT_SYMBOL(sg_copy_from_buffer); 468b1adaf65SFUJITA Tomonori 469b1adaf65SFUJITA Tomonori /** 470b1adaf65SFUJITA Tomonori * sg_copy_to_buffer - Copy from an SG list to a linear buffer 471b1adaf65SFUJITA Tomonori * @sgl: The SG list 472b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 473b1adaf65SFUJITA Tomonori * @buf: Where to copy to 474b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 475b1adaf65SFUJITA Tomonori * 476b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 477b1adaf65SFUJITA Tomonori * 478b1adaf65SFUJITA Tomonori **/ 479b1adaf65SFUJITA Tomonori size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, 480b1adaf65SFUJITA Tomonori void *buf, size_t buflen) 481b1adaf65SFUJITA Tomonori { 482b1adaf65SFUJITA Tomonori return sg_copy_buffer(sgl, nents, buf, buflen, 1); 483b1adaf65SFUJITA Tomonori } 484b1adaf65SFUJITA Tomonori EXPORT_SYMBOL(sg_copy_to_buffer); 485