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 */ 98bc3bcc9SPaul Gortmaker #include <linux/export.h> 105a0e3ad6STejun Heo #include <linux/slab.h> 110db9299fSJens Axboe #include <linux/scatterlist.h> 12b1adaf65SFUJITA Tomonori #include <linux/highmem.h> 13b94de9bbSChris Wilson #include <linux/kmemleak.h> 140db9299fSJens Axboe 150db9299fSJens Axboe /** 160db9299fSJens Axboe * sg_next - return the next scatterlist entry in a list 170db9299fSJens Axboe * @sg: The current sg entry 180db9299fSJens Axboe * 190db9299fSJens Axboe * Description: 200db9299fSJens Axboe * Usually the next entry will be @sg@ + 1, but if this sg element is part 210db9299fSJens Axboe * of a chained scatterlist, it could jump to the start of a new 220db9299fSJens Axboe * scatterlist array. 230db9299fSJens Axboe * 240db9299fSJens Axboe **/ 250db9299fSJens Axboe struct scatterlist *sg_next(struct scatterlist *sg) 260db9299fSJens Axboe { 270db9299fSJens Axboe #ifdef CONFIG_DEBUG_SG 280db9299fSJens Axboe BUG_ON(sg->sg_magic != SG_MAGIC); 290db9299fSJens Axboe #endif 300db9299fSJens Axboe if (sg_is_last(sg)) 310db9299fSJens Axboe return NULL; 320db9299fSJens Axboe 330db9299fSJens Axboe sg++; 340db9299fSJens Axboe if (unlikely(sg_is_chain(sg))) 350db9299fSJens Axboe sg = sg_chain_ptr(sg); 360db9299fSJens Axboe 370db9299fSJens Axboe return sg; 380db9299fSJens Axboe } 390db9299fSJens Axboe EXPORT_SYMBOL(sg_next); 400db9299fSJens Axboe 410db9299fSJens Axboe /** 422e484610SMaxim Levitsky * sg_nents - return total count of entries in scatterlist 432e484610SMaxim Levitsky * @sg: The scatterlist 442e484610SMaxim Levitsky * 452e484610SMaxim Levitsky * Description: 462e484610SMaxim Levitsky * Allows to know how many entries are in sg, taking into acount 472e484610SMaxim Levitsky * chaining as well 482e484610SMaxim Levitsky * 492e484610SMaxim Levitsky **/ 502e484610SMaxim Levitsky int sg_nents(struct scatterlist *sg) 512e484610SMaxim Levitsky { 52232f1b51SMaxim Levitsky int nents; 53232f1b51SMaxim Levitsky for (nents = 0; sg; sg = sg_next(sg)) 542e484610SMaxim Levitsky nents++; 552e484610SMaxim Levitsky return nents; 562e484610SMaxim Levitsky } 572e484610SMaxim Levitsky EXPORT_SYMBOL(sg_nents); 582e484610SMaxim Levitsky 59cfaed10dSTom Lendacky /** 60cfaed10dSTom Lendacky * sg_nents_for_len - return total count of entries in scatterlist 61cfaed10dSTom Lendacky * needed to satisfy the supplied length 62cfaed10dSTom Lendacky * @sg: The scatterlist 63cfaed10dSTom Lendacky * @len: The total required length 64cfaed10dSTom Lendacky * 65cfaed10dSTom Lendacky * Description: 66cfaed10dSTom Lendacky * Determines the number of entries in sg that are required to meet 67cfaed10dSTom Lendacky * the supplied length, taking into acount chaining as well 68cfaed10dSTom Lendacky * 69cfaed10dSTom Lendacky * Returns: 70cfaed10dSTom Lendacky * the number of sg entries needed, negative error on failure 71cfaed10dSTom Lendacky * 72cfaed10dSTom Lendacky **/ 73cfaed10dSTom Lendacky int sg_nents_for_len(struct scatterlist *sg, u64 len) 74cfaed10dSTom Lendacky { 75cfaed10dSTom Lendacky int nents; 76cfaed10dSTom Lendacky u64 total; 77cfaed10dSTom Lendacky 78cfaed10dSTom Lendacky if (!len) 79cfaed10dSTom Lendacky return 0; 80cfaed10dSTom Lendacky 81cfaed10dSTom Lendacky for (nents = 0, total = 0; sg; sg = sg_next(sg)) { 82cfaed10dSTom Lendacky nents++; 83cfaed10dSTom Lendacky total += sg->length; 84cfaed10dSTom Lendacky if (total >= len) 85cfaed10dSTom Lendacky return nents; 86cfaed10dSTom Lendacky } 87cfaed10dSTom Lendacky 88cfaed10dSTom Lendacky return -EINVAL; 89cfaed10dSTom Lendacky } 90cfaed10dSTom Lendacky EXPORT_SYMBOL(sg_nents_for_len); 912e484610SMaxim Levitsky 922e484610SMaxim Levitsky /** 930db9299fSJens Axboe * sg_last - return the last scatterlist entry in a list 940db9299fSJens Axboe * @sgl: First entry in the scatterlist 950db9299fSJens Axboe * @nents: Number of entries in the scatterlist 960db9299fSJens Axboe * 970db9299fSJens Axboe * Description: 980db9299fSJens Axboe * Should only be used casually, it (currently) scans the entire list 990db9299fSJens Axboe * to get the last entry. 1000db9299fSJens Axboe * 1010db9299fSJens Axboe * Note that the @sgl@ pointer passed in need not be the first one, 1020db9299fSJens Axboe * the important bit is that @nents@ denotes the number of entries that 1030db9299fSJens Axboe * exist from @sgl@. 1040db9299fSJens Axboe * 1050db9299fSJens Axboe **/ 1060db9299fSJens Axboe struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) 1070db9299fSJens Axboe { 1080db9299fSJens Axboe struct scatterlist *sg, *ret = NULL; 1090db9299fSJens Axboe unsigned int i; 1100db9299fSJens Axboe 1110db9299fSJens Axboe for_each_sg(sgl, sg, nents, i) 1120db9299fSJens Axboe ret = sg; 1130db9299fSJens Axboe 1140db9299fSJens Axboe #ifdef CONFIG_DEBUG_SG 1150db9299fSJens Axboe BUG_ON(sgl[0].sg_magic != SG_MAGIC); 1160db9299fSJens Axboe BUG_ON(!sg_is_last(ret)); 1170db9299fSJens Axboe #endif 1180db9299fSJens Axboe return ret; 1190db9299fSJens Axboe } 1200db9299fSJens Axboe EXPORT_SYMBOL(sg_last); 1210db9299fSJens Axboe 1220db9299fSJens Axboe /** 1230db9299fSJens Axboe * sg_init_table - Initialize SG table 1240db9299fSJens Axboe * @sgl: The SG table 1250db9299fSJens Axboe * @nents: Number of entries in table 1260db9299fSJens Axboe * 1270db9299fSJens Axboe * Notes: 1280db9299fSJens Axboe * If this is part of a chained sg table, sg_mark_end() should be 1290db9299fSJens Axboe * used only on the last table part. 1300db9299fSJens Axboe * 1310db9299fSJens Axboe **/ 1320db9299fSJens Axboe void sg_init_table(struct scatterlist *sgl, unsigned int nents) 1330db9299fSJens Axboe { 1340db9299fSJens Axboe memset(sgl, 0, sizeof(*sgl) * nents); 1350db9299fSJens Axboe #ifdef CONFIG_DEBUG_SG 1360db9299fSJens Axboe { 1370db9299fSJens Axboe unsigned int i; 1380db9299fSJens Axboe for (i = 0; i < nents; i++) 1390db9299fSJens Axboe sgl[i].sg_magic = SG_MAGIC; 1400db9299fSJens Axboe } 1410db9299fSJens Axboe #endif 1420db9299fSJens Axboe sg_mark_end(&sgl[nents - 1]); 1430db9299fSJens Axboe } 1440db9299fSJens Axboe EXPORT_SYMBOL(sg_init_table); 1450db9299fSJens Axboe 1460db9299fSJens Axboe /** 1470db9299fSJens Axboe * sg_init_one - Initialize a single entry sg list 1480db9299fSJens Axboe * @sg: SG entry 1490db9299fSJens Axboe * @buf: Virtual address for IO 1500db9299fSJens Axboe * @buflen: IO length 1510db9299fSJens Axboe * 1520db9299fSJens Axboe **/ 1530db9299fSJens Axboe void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) 1540db9299fSJens Axboe { 1550db9299fSJens Axboe sg_init_table(sg, 1); 1560db9299fSJens Axboe sg_set_buf(sg, buf, buflen); 1570db9299fSJens Axboe } 1580db9299fSJens Axboe EXPORT_SYMBOL(sg_init_one); 1590db9299fSJens Axboe 1600db9299fSJens Axboe /* 1610db9299fSJens Axboe * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree 1620db9299fSJens Axboe * helpers. 1630db9299fSJens Axboe */ 1640db9299fSJens Axboe static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) 1650db9299fSJens Axboe { 166b94de9bbSChris Wilson if (nents == SG_MAX_SINGLE_ALLOC) { 167b94de9bbSChris Wilson /* 168b94de9bbSChris Wilson * Kmemleak doesn't track page allocations as they are not 169b94de9bbSChris Wilson * commonly used (in a raw form) for kernel data structures. 170b94de9bbSChris Wilson * As we chain together a list of pages and then a normal 171b94de9bbSChris Wilson * kmalloc (tracked by kmemleak), in order to for that last 172b94de9bbSChris Wilson * allocation not to become decoupled (and thus a 173b94de9bbSChris Wilson * false-positive) we need to inform kmemleak of all the 174b94de9bbSChris Wilson * intermediate allocations. 175b94de9bbSChris Wilson */ 176b94de9bbSChris Wilson void *ptr = (void *) __get_free_page(gfp_mask); 177b94de9bbSChris Wilson kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask); 178b94de9bbSChris Wilson return ptr; 179b94de9bbSChris Wilson } else 1800db9299fSJens Axboe return kmalloc(nents * sizeof(struct scatterlist), gfp_mask); 1810db9299fSJens Axboe } 1820db9299fSJens Axboe 1830db9299fSJens Axboe static void sg_kfree(struct scatterlist *sg, unsigned int nents) 1840db9299fSJens Axboe { 185b94de9bbSChris Wilson if (nents == SG_MAX_SINGLE_ALLOC) { 186b94de9bbSChris Wilson kmemleak_free(sg); 1870db9299fSJens Axboe free_page((unsigned long) sg); 188b94de9bbSChris Wilson } else 1890db9299fSJens Axboe kfree(sg); 1900db9299fSJens Axboe } 1910db9299fSJens Axboe 1920db9299fSJens Axboe /** 1930db9299fSJens Axboe * __sg_free_table - Free a previously mapped sg table 1940db9299fSJens Axboe * @table: The sg table header to use 1957cedb1f1SJames Bottomley * @max_ents: The maximum number of entries per single scatterlist 196c53c6d6aSChristoph Hellwig * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk 1970db9299fSJens Axboe * @free_fn: Free function 1980db9299fSJens Axboe * 1990db9299fSJens Axboe * Description: 2007cedb1f1SJames Bottomley * Free an sg table previously allocated and setup with 2017cedb1f1SJames Bottomley * __sg_alloc_table(). The @max_ents value must be identical to 2027cedb1f1SJames Bottomley * that previously used with __sg_alloc_table(). 2030db9299fSJens Axboe * 2040db9299fSJens Axboe **/ 2057cedb1f1SJames Bottomley void __sg_free_table(struct sg_table *table, unsigned int max_ents, 206c53c6d6aSChristoph Hellwig bool skip_first_chunk, sg_free_fn *free_fn) 2070db9299fSJens Axboe { 2080db9299fSJens Axboe struct scatterlist *sgl, *next; 2090db9299fSJens Axboe 2100db9299fSJens Axboe if (unlikely(!table->sgl)) 2110db9299fSJens Axboe return; 2120db9299fSJens Axboe 2130db9299fSJens Axboe sgl = table->sgl; 2140db9299fSJens Axboe while (table->orig_nents) { 2150db9299fSJens Axboe unsigned int alloc_size = table->orig_nents; 2160db9299fSJens Axboe unsigned int sg_size; 2170db9299fSJens Axboe 2180db9299fSJens Axboe /* 2197cedb1f1SJames Bottomley * If we have more than max_ents segments left, 2200db9299fSJens Axboe * then assign 'next' to the sg table after the current one. 2210db9299fSJens Axboe * sg_size is then one less than alloc size, since the last 2220db9299fSJens Axboe * element is the chain pointer. 2230db9299fSJens Axboe */ 2247cedb1f1SJames Bottomley if (alloc_size > max_ents) { 2257cedb1f1SJames Bottomley next = sg_chain_ptr(&sgl[max_ents - 1]); 2267cedb1f1SJames Bottomley alloc_size = max_ents; 2270db9299fSJens Axboe sg_size = alloc_size - 1; 2280db9299fSJens Axboe } else { 2290db9299fSJens Axboe sg_size = alloc_size; 2300db9299fSJens Axboe next = NULL; 2310db9299fSJens Axboe } 2320db9299fSJens Axboe 2330db9299fSJens Axboe table->orig_nents -= sg_size; 234c21e59d8STony Battersby if (skip_first_chunk) 235c53c6d6aSChristoph Hellwig skip_first_chunk = false; 236c21e59d8STony Battersby else 237c21e59d8STony Battersby free_fn(sgl, alloc_size); 2380db9299fSJens Axboe sgl = next; 2390db9299fSJens Axboe } 2400db9299fSJens Axboe 2410db9299fSJens Axboe table->sgl = NULL; 2420db9299fSJens Axboe } 2430db9299fSJens Axboe EXPORT_SYMBOL(__sg_free_table); 2440db9299fSJens Axboe 2450db9299fSJens Axboe /** 2460db9299fSJens Axboe * sg_free_table - Free a previously allocated sg table 2470db9299fSJens Axboe * @table: The mapped sg table header 2480db9299fSJens Axboe * 2490db9299fSJens Axboe **/ 2500db9299fSJens Axboe void sg_free_table(struct sg_table *table) 2510db9299fSJens Axboe { 252c53c6d6aSChristoph Hellwig __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); 2530db9299fSJens Axboe } 2540db9299fSJens Axboe EXPORT_SYMBOL(sg_free_table); 2550db9299fSJens Axboe 2560db9299fSJens Axboe /** 2570db9299fSJens Axboe * __sg_alloc_table - Allocate and initialize an sg table with given allocator 2580db9299fSJens Axboe * @table: The sg table header to use 2590db9299fSJens Axboe * @nents: Number of entries in sg list 2607cedb1f1SJames Bottomley * @max_ents: The maximum number of entries the allocator returns per call 2610db9299fSJens Axboe * @gfp_mask: GFP allocation mask 2620db9299fSJens Axboe * @alloc_fn: Allocator to use 2630db9299fSJens Axboe * 2647cedb1f1SJames Bottomley * Description: 2657cedb1f1SJames Bottomley * This function returns a @table @nents long. The allocator is 2667cedb1f1SJames Bottomley * defined to return scatterlist chunks of maximum size @max_ents. 2677cedb1f1SJames Bottomley * Thus if @nents is bigger than @max_ents, the scatterlists will be 2687cedb1f1SJames Bottomley * chained in units of @max_ents. 2697cedb1f1SJames Bottomley * 2700db9299fSJens Axboe * Notes: 2710db9299fSJens Axboe * If this function returns non-0 (eg failure), the caller must call 2720db9299fSJens Axboe * __sg_free_table() to cleanup any leftover allocations. 2730db9299fSJens Axboe * 2740db9299fSJens Axboe **/ 2757cedb1f1SJames Bottomley int __sg_alloc_table(struct sg_table *table, unsigned int nents, 276c53c6d6aSChristoph Hellwig unsigned int max_ents, struct scatterlist *first_chunk, 277c53c6d6aSChristoph Hellwig gfp_t gfp_mask, sg_alloc_fn *alloc_fn) 2780db9299fSJens Axboe { 2790db9299fSJens Axboe struct scatterlist *sg, *prv; 2800db9299fSJens Axboe unsigned int left; 2810db9299fSJens Axboe 28227daabd9SDan Carpenter memset(table, 0, sizeof(*table)); 28327daabd9SDan Carpenter 28427daabd9SDan Carpenter if (nents == 0) 28527daabd9SDan Carpenter return -EINVAL; 286308c09f1SLaura Abbott #ifndef CONFIG_ARCH_HAS_SG_CHAIN 2876fd59a83SNick Bowler if (WARN_ON_ONCE(nents > max_ents)) 2886fd59a83SNick Bowler return -EINVAL; 2890db9299fSJens Axboe #endif 2900db9299fSJens Axboe 2910db9299fSJens Axboe left = nents; 2920db9299fSJens Axboe prv = NULL; 2930db9299fSJens Axboe do { 2940db9299fSJens Axboe unsigned int sg_size, alloc_size = left; 2950db9299fSJens Axboe 2967cedb1f1SJames Bottomley if (alloc_size > max_ents) { 2977cedb1f1SJames Bottomley alloc_size = max_ents; 2980db9299fSJens Axboe sg_size = alloc_size - 1; 2990db9299fSJens Axboe } else 3000db9299fSJens Axboe sg_size = alloc_size; 3010db9299fSJens Axboe 3020db9299fSJens Axboe left -= sg_size; 3030db9299fSJens Axboe 304c53c6d6aSChristoph Hellwig if (first_chunk) { 305c53c6d6aSChristoph Hellwig sg = first_chunk; 306c53c6d6aSChristoph Hellwig first_chunk = NULL; 307c53c6d6aSChristoph Hellwig } else { 3080db9299fSJens Axboe sg = alloc_fn(alloc_size, gfp_mask); 309c53c6d6aSChristoph Hellwig } 310edce6820SJeffrey Carlyle if (unlikely(!sg)) { 311edce6820SJeffrey Carlyle /* 312edce6820SJeffrey Carlyle * Adjust entry count to reflect that the last 313edce6820SJeffrey Carlyle * entry of the previous table won't be used for 314edce6820SJeffrey Carlyle * linkage. Without this, sg_kfree() may get 315edce6820SJeffrey Carlyle * confused. 316edce6820SJeffrey Carlyle */ 317edce6820SJeffrey Carlyle if (prv) 318edce6820SJeffrey Carlyle table->nents = ++table->orig_nents; 319edce6820SJeffrey Carlyle 3200db9299fSJens Axboe return -ENOMEM; 321edce6820SJeffrey Carlyle } 3220db9299fSJens Axboe 3230db9299fSJens Axboe sg_init_table(sg, alloc_size); 3240db9299fSJens Axboe table->nents = table->orig_nents += sg_size; 3250db9299fSJens Axboe 3260db9299fSJens Axboe /* 3270db9299fSJens Axboe * If this is the first mapping, assign the sg table header. 3280db9299fSJens Axboe * If this is not the first mapping, chain previous part. 3290db9299fSJens Axboe */ 3300db9299fSJens Axboe if (prv) 3317cedb1f1SJames Bottomley sg_chain(prv, max_ents, sg); 3320db9299fSJens Axboe else 3330db9299fSJens Axboe table->sgl = sg; 3340db9299fSJens Axboe 3350db9299fSJens Axboe /* 3360db9299fSJens Axboe * If no more entries after this one, mark the end 3370db9299fSJens Axboe */ 3380db9299fSJens Axboe if (!left) 3390db9299fSJens Axboe sg_mark_end(&sg[sg_size - 1]); 3400db9299fSJens Axboe 3410db9299fSJens Axboe prv = sg; 3420db9299fSJens Axboe } while (left); 3430db9299fSJens Axboe 3440db9299fSJens Axboe return 0; 3450db9299fSJens Axboe } 3460db9299fSJens Axboe EXPORT_SYMBOL(__sg_alloc_table); 3470db9299fSJens Axboe 3480db9299fSJens Axboe /** 3490db9299fSJens Axboe * sg_alloc_table - Allocate and initialize an sg table 3500db9299fSJens Axboe * @table: The sg table header to use 3510db9299fSJens Axboe * @nents: Number of entries in sg list 3520db9299fSJens Axboe * @gfp_mask: GFP allocation mask 3530db9299fSJens Axboe * 3540db9299fSJens Axboe * Description: 3550db9299fSJens Axboe * Allocate and initialize an sg table. If @nents@ is larger than 3560db9299fSJens Axboe * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 3570db9299fSJens Axboe * 3580db9299fSJens Axboe **/ 3590db9299fSJens Axboe int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 3600db9299fSJens Axboe { 3610db9299fSJens Axboe int ret; 3620db9299fSJens Axboe 3637cedb1f1SJames Bottomley ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 364c53c6d6aSChristoph Hellwig NULL, gfp_mask, sg_kmalloc); 3650db9299fSJens Axboe if (unlikely(ret)) 366c53c6d6aSChristoph Hellwig __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); 3670db9299fSJens Axboe 3680db9299fSJens Axboe return ret; 3690db9299fSJens Axboe } 3700db9299fSJens Axboe EXPORT_SYMBOL(sg_alloc_table); 371b1adaf65SFUJITA Tomonori 372b1adaf65SFUJITA Tomonori /** 37389d8589cSTvrtko Ursulin * __sg_alloc_table_from_pages - Allocate and initialize an sg table from 374efc42bc9STomasz Stanislawski * an array of pages 375efc42bc9STomasz Stanislawski * @sgt: The sg table header to use 376efc42bc9STomasz Stanislawski * @pages: Pointer to an array of page pointers 377efc42bc9STomasz Stanislawski * @n_pages: Number of pages in the pages array 378efc42bc9STomasz Stanislawski * @offset: Offset from start of the first page to the start of a buffer 379efc42bc9STomasz Stanislawski * @size: Number of valid bytes in the buffer (after offset) 38089d8589cSTvrtko Ursulin * @max_segment: Maximum size of a scatterlist node in bytes (page aligned) 381efc42bc9STomasz Stanislawski * @gfp_mask: GFP allocation mask 382efc42bc9STomasz Stanislawski * 383efc42bc9STomasz Stanislawski * Description: 384efc42bc9STomasz Stanislawski * Allocate and initialize an sg table from a list of pages. Contiguous 38589d8589cSTvrtko Ursulin * ranges of the pages are squashed into a single scatterlist node up to the 38689d8589cSTvrtko Ursulin * maximum size specified in @max_segment. An user may provide an offset at a 38789d8589cSTvrtko Ursulin * start and a size of valid data in a buffer specified by the page array. 38889d8589cSTvrtko Ursulin * The returned sg table is released by sg_free_table. 389efc42bc9STomasz Stanislawski * 390efc42bc9STomasz Stanislawski * Returns: 391efc42bc9STomasz Stanislawski * 0 on success, negative error on failure 392efc42bc9STomasz Stanislawski */ 39389d8589cSTvrtko Ursulin int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, 39489d8589cSTvrtko Ursulin unsigned int n_pages, unsigned int offset, 39589d8589cSTvrtko Ursulin unsigned long size, unsigned int max_segment, 396efc42bc9STomasz Stanislawski gfp_t gfp_mask) 397efc42bc9STomasz Stanislawski { 398c125906bSTvrtko Ursulin unsigned int chunks, cur_page, seg_len, i; 399efc42bc9STomasz Stanislawski int ret; 400efc42bc9STomasz Stanislawski struct scatterlist *s; 401efc42bc9STomasz Stanislawski 40289d8589cSTvrtko Ursulin if (WARN_ON(!max_segment || offset_in_page(max_segment))) 40389d8589cSTvrtko Ursulin return -EINVAL; 40489d8589cSTvrtko Ursulin 405efc42bc9STomasz Stanislawski /* compute number of contiguous chunks */ 406efc42bc9STomasz Stanislawski chunks = 1; 407c125906bSTvrtko Ursulin seg_len = 0; 408c125906bSTvrtko Ursulin for (i = 1; i < n_pages; i++) { 409c125906bSTvrtko Ursulin seg_len += PAGE_SIZE; 410c125906bSTvrtko Ursulin if (seg_len >= max_segment || 411c125906bSTvrtko Ursulin page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) { 412c125906bSTvrtko Ursulin chunks++; 413c125906bSTvrtko Ursulin seg_len = 0; 414c125906bSTvrtko Ursulin } 415c125906bSTvrtko Ursulin } 416efc42bc9STomasz Stanislawski 417efc42bc9STomasz Stanislawski ret = sg_alloc_table(sgt, chunks, gfp_mask); 418efc42bc9STomasz Stanislawski if (unlikely(ret)) 419efc42bc9STomasz Stanislawski return ret; 420efc42bc9STomasz Stanislawski 421efc42bc9STomasz Stanislawski /* merging chunks and putting them into the scatterlist */ 422efc42bc9STomasz Stanislawski cur_page = 0; 423efc42bc9STomasz Stanislawski for_each_sg(sgt->sgl, s, sgt->orig_nents, i) { 424c125906bSTvrtko Ursulin unsigned int j, chunk_size; 425efc42bc9STomasz Stanislawski 426efc42bc9STomasz Stanislawski /* look for the end of the current chunk */ 427c125906bSTvrtko Ursulin seg_len = 0; 428c125906bSTvrtko Ursulin for (j = cur_page + 1; j < n_pages; j++) { 429c125906bSTvrtko Ursulin seg_len += PAGE_SIZE; 430c125906bSTvrtko Ursulin if (seg_len >= max_segment || 431c125906bSTvrtko Ursulin page_to_pfn(pages[j]) != 432efc42bc9STomasz Stanislawski page_to_pfn(pages[j - 1]) + 1) 433efc42bc9STomasz Stanislawski break; 434c125906bSTvrtko Ursulin } 435efc42bc9STomasz Stanislawski 436efc42bc9STomasz Stanislawski chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset; 437c125906bSTvrtko Ursulin sg_set_page(s, pages[cur_page], 438c125906bSTvrtko Ursulin min_t(unsigned long, size, chunk_size), offset); 439efc42bc9STomasz Stanislawski size -= chunk_size; 440efc42bc9STomasz Stanislawski offset = 0; 441efc42bc9STomasz Stanislawski cur_page = j; 442efc42bc9STomasz Stanislawski } 443efc42bc9STomasz Stanislawski 444efc42bc9STomasz Stanislawski return 0; 445efc42bc9STomasz Stanislawski } 44689d8589cSTvrtko Ursulin EXPORT_SYMBOL(__sg_alloc_table_from_pages); 44789d8589cSTvrtko Ursulin 44889d8589cSTvrtko Ursulin /** 44989d8589cSTvrtko Ursulin * sg_alloc_table_from_pages - Allocate and initialize an sg table from 45089d8589cSTvrtko Ursulin * an array of pages 45189d8589cSTvrtko Ursulin * @sgt: The sg table header to use 45289d8589cSTvrtko Ursulin * @pages: Pointer to an array of page pointers 45389d8589cSTvrtko Ursulin * @n_pages: Number of pages in the pages array 45489d8589cSTvrtko Ursulin * @offset: Offset from start of the first page to the start of a buffer 45589d8589cSTvrtko Ursulin * @size: Number of valid bytes in the buffer (after offset) 45689d8589cSTvrtko Ursulin * @gfp_mask: GFP allocation mask 45789d8589cSTvrtko Ursulin * 45889d8589cSTvrtko Ursulin * Description: 45989d8589cSTvrtko Ursulin * Allocate and initialize an sg table from a list of pages. Contiguous 46089d8589cSTvrtko Ursulin * ranges of the pages are squashed into a single scatterlist node. A user 46189d8589cSTvrtko Ursulin * may provide an offset at a start and a size of valid data in a buffer 46289d8589cSTvrtko Ursulin * specified by the page array. The returned sg table is released by 46389d8589cSTvrtko Ursulin * sg_free_table. 46489d8589cSTvrtko Ursulin * 46589d8589cSTvrtko Ursulin * Returns: 46689d8589cSTvrtko Ursulin * 0 on success, negative error on failure 46789d8589cSTvrtko Ursulin */ 46889d8589cSTvrtko Ursulin int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, 46989d8589cSTvrtko Ursulin unsigned int n_pages, unsigned int offset, 47089d8589cSTvrtko Ursulin unsigned long size, gfp_t gfp_mask) 47189d8589cSTvrtko Ursulin { 47289d8589cSTvrtko Ursulin return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size, 47389d8589cSTvrtko Ursulin SCATTERLIST_MAX_SEGMENT, gfp_mask); 47489d8589cSTvrtko Ursulin } 475efc42bc9STomasz Stanislawski EXPORT_SYMBOL(sg_alloc_table_from_pages); 476efc42bc9STomasz Stanislawski 477e80a0af4SBart Van Assche #ifdef CONFIG_SGL_ALLOC 478e80a0af4SBart Van Assche 479e80a0af4SBart Van Assche /** 480e80a0af4SBart Van Assche * sgl_alloc_order - allocate a scatterlist and its pages 481e80a0af4SBart Van Assche * @length: Length in bytes of the scatterlist. Must be at least one 482e80a0af4SBart Van Assche * @order: Second argument for alloc_pages() 483e80a0af4SBart Van Assche * @chainable: Whether or not to allocate an extra element in the scatterlist 484e80a0af4SBart Van Assche * for scatterlist chaining purposes 485e80a0af4SBart Van Assche * @gfp: Memory allocation flags 486e80a0af4SBart Van Assche * @nent_p: [out] Number of entries in the scatterlist that have pages 487e80a0af4SBart Van Assche * 488e80a0af4SBart Van Assche * Returns: A pointer to an initialized scatterlist or %NULL upon failure. 489e80a0af4SBart Van Assche */ 490e80a0af4SBart Van Assche struct scatterlist *sgl_alloc_order(unsigned long long length, 491e80a0af4SBart Van Assche unsigned int order, bool chainable, 492e80a0af4SBart Van Assche gfp_t gfp, unsigned int *nent_p) 493e80a0af4SBart Van Assche { 494e80a0af4SBart Van Assche struct scatterlist *sgl, *sg; 495e80a0af4SBart Van Assche struct page *page; 496e80a0af4SBart Van Assche unsigned int nent, nalloc; 497e80a0af4SBart Van Assche u32 elem_len; 498e80a0af4SBart Van Assche 499e80a0af4SBart Van Assche nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order); 500e80a0af4SBart Van Assche /* Check for integer overflow */ 501e80a0af4SBart Van Assche if (length > (nent << (PAGE_SHIFT + order))) 502e80a0af4SBart Van Assche return NULL; 503e80a0af4SBart Van Assche nalloc = nent; 504e80a0af4SBart Van Assche if (chainable) { 505e80a0af4SBart Van Assche /* Check for integer overflow */ 506e80a0af4SBart Van Assche if (nalloc + 1 < nalloc) 507e80a0af4SBart Van Assche return NULL; 508e80a0af4SBart Van Assche nalloc++; 509e80a0af4SBart Van Assche } 510e80a0af4SBart Van Assche sgl = kmalloc_array(nalloc, sizeof(struct scatterlist), 511e80a0af4SBart Van Assche (gfp & ~GFP_DMA) | __GFP_ZERO); 512e80a0af4SBart Van Assche if (!sgl) 513e80a0af4SBart Van Assche return NULL; 514e80a0af4SBart Van Assche 515e80a0af4SBart Van Assche sg_init_table(sgl, nent); 516e80a0af4SBart Van Assche sg = sgl; 517e80a0af4SBart Van Assche while (length) { 518e80a0af4SBart Van Assche elem_len = min_t(u64, length, PAGE_SIZE << order); 519e80a0af4SBart Van Assche page = alloc_pages(gfp, order); 520e80a0af4SBart Van Assche if (!page) { 521e80a0af4SBart Van Assche sgl_free(sgl); 522e80a0af4SBart Van Assche return NULL; 523e80a0af4SBart Van Assche } 524e80a0af4SBart Van Assche 525e80a0af4SBart Van Assche sg_set_page(sg, page, elem_len, 0); 526e80a0af4SBart Van Assche length -= elem_len; 527e80a0af4SBart Van Assche sg = sg_next(sg); 528e80a0af4SBart Van Assche } 529e80a0af4SBart Van Assche WARN_ON_ONCE(sg); 530e80a0af4SBart Van Assche if (nent_p) 531e80a0af4SBart Van Assche *nent_p = nent; 532e80a0af4SBart Van Assche return sgl; 533e80a0af4SBart Van Assche } 534e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_alloc_order); 535e80a0af4SBart Van Assche 536e80a0af4SBart Van Assche /** 537e80a0af4SBart Van Assche * sgl_alloc - allocate a scatterlist and its pages 538e80a0af4SBart Van Assche * @length: Length in bytes of the scatterlist 539e80a0af4SBart Van Assche * @gfp: Memory allocation flags 540e80a0af4SBart Van Assche * @nent_p: [out] Number of entries in the scatterlist 541e80a0af4SBart Van Assche * 542e80a0af4SBart Van Assche * Returns: A pointer to an initialized scatterlist or %NULL upon failure. 543e80a0af4SBart Van Assche */ 544e80a0af4SBart Van Assche struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, 545e80a0af4SBart Van Assche unsigned int *nent_p) 546e80a0af4SBart Van Assche { 547e80a0af4SBart Van Assche return sgl_alloc_order(length, 0, false, gfp, nent_p); 548e80a0af4SBart Van Assche } 549e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_alloc); 550e80a0af4SBart Van Assche 551e80a0af4SBart Van Assche /** 552e80a0af4SBart Van Assche * sgl_free_order - free a scatterlist and its pages 553e80a0af4SBart Van Assche * @sgl: Scatterlist with one or more elements 554e80a0af4SBart Van Assche * @order: Second argument for __free_pages() 555e80a0af4SBart Van Assche */ 556e80a0af4SBart Van Assche void sgl_free_order(struct scatterlist *sgl, int order) 557e80a0af4SBart Van Assche { 558e80a0af4SBart Van Assche struct scatterlist *sg; 559e80a0af4SBart Van Assche struct page *page; 560e80a0af4SBart Van Assche 561e80a0af4SBart Van Assche for (sg = sgl; sg; sg = sg_next(sg)) { 562e80a0af4SBart Van Assche page = sg_page(sg); 563e80a0af4SBart Van Assche if (page) 564e80a0af4SBart Van Assche __free_pages(page, order); 565e80a0af4SBart Van Assche } 566e80a0af4SBart Van Assche kfree(sgl); 567e80a0af4SBart Van Assche } 568e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_free_order); 569e80a0af4SBart Van Assche 570e80a0af4SBart Van Assche /** 571e80a0af4SBart Van Assche * sgl_free - free a scatterlist and its pages 572e80a0af4SBart Van Assche * @sgl: Scatterlist with one or more elements 573e80a0af4SBart Van Assche */ 574e80a0af4SBart Van Assche void sgl_free(struct scatterlist *sgl) 575e80a0af4SBart Van Assche { 576e80a0af4SBart Van Assche sgl_free_order(sgl, 0); 577e80a0af4SBart Van Assche } 578e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_free); 579e80a0af4SBart Van Assche 580e80a0af4SBart Van Assche #endif /* CONFIG_SGL_ALLOC */ 581e80a0af4SBart Van Assche 582a321e91bSImre Deak void __sg_page_iter_start(struct sg_page_iter *piter, 583a321e91bSImre Deak struct scatterlist *sglist, unsigned int nents, 584a321e91bSImre Deak unsigned long pgoffset) 585a321e91bSImre Deak { 586a321e91bSImre Deak piter->__pg_advance = 0; 587a321e91bSImre Deak piter->__nents = nents; 588a321e91bSImre Deak 589a321e91bSImre Deak piter->sg = sglist; 590a321e91bSImre Deak piter->sg_pgoffset = pgoffset; 591a321e91bSImre Deak } 592a321e91bSImre Deak EXPORT_SYMBOL(__sg_page_iter_start); 593a321e91bSImre Deak 594a321e91bSImre Deak static int sg_page_count(struct scatterlist *sg) 595a321e91bSImre Deak { 596a321e91bSImre Deak return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; 597a321e91bSImre Deak } 598a321e91bSImre Deak 599a321e91bSImre Deak bool __sg_page_iter_next(struct sg_page_iter *piter) 600a321e91bSImre Deak { 601a321e91bSImre Deak if (!piter->__nents || !piter->sg) 602a321e91bSImre Deak return false; 603a321e91bSImre Deak 604a321e91bSImre Deak piter->sg_pgoffset += piter->__pg_advance; 605a321e91bSImre Deak piter->__pg_advance = 1; 606a321e91bSImre Deak 607a321e91bSImre Deak while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { 608a321e91bSImre Deak piter->sg_pgoffset -= sg_page_count(piter->sg); 609a321e91bSImre Deak piter->sg = sg_next(piter->sg); 610a321e91bSImre Deak if (!--piter->__nents || !piter->sg) 611a321e91bSImre Deak return false; 612a321e91bSImre Deak } 613a321e91bSImre Deak 614a321e91bSImre Deak return true; 615a321e91bSImre Deak } 616a321e91bSImre Deak EXPORT_SYMBOL(__sg_page_iter_next); 617a321e91bSImre Deak 618efc42bc9STomasz Stanislawski /** 619137d3edbSTejun Heo * sg_miter_start - start mapping iteration over a sg list 620137d3edbSTejun Heo * @miter: sg mapping iter to be started 621137d3edbSTejun Heo * @sgl: sg list to iterate over 622137d3edbSTejun Heo * @nents: number of sg entries 623137d3edbSTejun Heo * 624137d3edbSTejun Heo * Description: 625137d3edbSTejun Heo * Starts mapping iterator @miter. 626137d3edbSTejun Heo * 627137d3edbSTejun Heo * Context: 628137d3edbSTejun Heo * Don't care. 629137d3edbSTejun Heo */ 630137d3edbSTejun Heo void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, 631137d3edbSTejun Heo unsigned int nents, unsigned int flags) 632137d3edbSTejun Heo { 633137d3edbSTejun Heo memset(miter, 0, sizeof(struct sg_mapping_iter)); 634137d3edbSTejun Heo 6354225fc85SImre Deak __sg_page_iter_start(&miter->piter, sgl, nents, 0); 6366de7e356SSebastian Andrzej Siewior WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); 637137d3edbSTejun Heo miter->__flags = flags; 638137d3edbSTejun Heo } 639137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_start); 640137d3edbSTejun Heo 64111052004SAkinobu Mita static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) 64211052004SAkinobu Mita { 64311052004SAkinobu Mita if (!miter->__remaining) { 64411052004SAkinobu Mita struct scatterlist *sg; 64511052004SAkinobu Mita unsigned long pgoffset; 64611052004SAkinobu Mita 64711052004SAkinobu Mita if (!__sg_page_iter_next(&miter->piter)) 64811052004SAkinobu Mita return false; 64911052004SAkinobu Mita 65011052004SAkinobu Mita sg = miter->piter.sg; 65111052004SAkinobu Mita pgoffset = miter->piter.sg_pgoffset; 65211052004SAkinobu Mita 65311052004SAkinobu Mita miter->__offset = pgoffset ? 0 : sg->offset; 65411052004SAkinobu Mita miter->__remaining = sg->offset + sg->length - 65511052004SAkinobu Mita (pgoffset << PAGE_SHIFT) - miter->__offset; 65611052004SAkinobu Mita miter->__remaining = min_t(unsigned long, miter->__remaining, 65711052004SAkinobu Mita PAGE_SIZE - miter->__offset); 65811052004SAkinobu Mita } 65911052004SAkinobu Mita 66011052004SAkinobu Mita return true; 66111052004SAkinobu Mita } 66211052004SAkinobu Mita 663137d3edbSTejun Heo /** 664df642ceaSAkinobu Mita * sg_miter_skip - reposition mapping iterator 665df642ceaSAkinobu Mita * @miter: sg mapping iter to be skipped 666df642ceaSAkinobu Mita * @offset: number of bytes to plus the current location 667df642ceaSAkinobu Mita * 668df642ceaSAkinobu Mita * Description: 669df642ceaSAkinobu Mita * Sets the offset of @miter to its current location plus @offset bytes. 670df642ceaSAkinobu Mita * If mapping iterator @miter has been proceeded by sg_miter_next(), this 671df642ceaSAkinobu Mita * stops @miter. 672df642ceaSAkinobu Mita * 673df642ceaSAkinobu Mita * Context: 674df642ceaSAkinobu Mita * Don't care if @miter is stopped, or not proceeded yet. 675df642ceaSAkinobu Mita * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set. 676df642ceaSAkinobu Mita * 677df642ceaSAkinobu Mita * Returns: 678df642ceaSAkinobu Mita * true if @miter contains the valid mapping. false if end of sg 679df642ceaSAkinobu Mita * list is reached. 680df642ceaSAkinobu Mita */ 6810d6077f8SMing Lei bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) 682df642ceaSAkinobu Mita { 683df642ceaSAkinobu Mita sg_miter_stop(miter); 684df642ceaSAkinobu Mita 685df642ceaSAkinobu Mita while (offset) { 686df642ceaSAkinobu Mita off_t consumed; 687df642ceaSAkinobu Mita 688df642ceaSAkinobu Mita if (!sg_miter_get_next_page(miter)) 689df642ceaSAkinobu Mita return false; 690df642ceaSAkinobu Mita 691df642ceaSAkinobu Mita consumed = min_t(off_t, offset, miter->__remaining); 692df642ceaSAkinobu Mita miter->__offset += consumed; 693df642ceaSAkinobu Mita miter->__remaining -= consumed; 694df642ceaSAkinobu Mita offset -= consumed; 695df642ceaSAkinobu Mita } 696df642ceaSAkinobu Mita 697df642ceaSAkinobu Mita return true; 698df642ceaSAkinobu Mita } 6990d6077f8SMing Lei EXPORT_SYMBOL(sg_miter_skip); 700df642ceaSAkinobu Mita 701df642ceaSAkinobu Mita /** 702137d3edbSTejun Heo * sg_miter_next - proceed mapping iterator to the next mapping 703137d3edbSTejun Heo * @miter: sg mapping iter to proceed 704137d3edbSTejun Heo * 705137d3edbSTejun Heo * Description: 7068290e2d2STejun Heo * Proceeds @miter to the next mapping. @miter should have been started 7078290e2d2STejun Heo * using sg_miter_start(). On successful return, @miter->page, 7088290e2d2STejun Heo * @miter->addr and @miter->length point to the current mapping. 709137d3edbSTejun Heo * 710137d3edbSTejun Heo * Context: 7118290e2d2STejun Heo * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled 7128290e2d2STejun Heo * till @miter is stopped. May sleep if !SG_MITER_ATOMIC. 713137d3edbSTejun Heo * 714137d3edbSTejun Heo * Returns: 715137d3edbSTejun Heo * true if @miter contains the next mapping. false if end of sg 716137d3edbSTejun Heo * list is reached. 717137d3edbSTejun Heo */ 718137d3edbSTejun Heo bool sg_miter_next(struct sg_mapping_iter *miter) 719137d3edbSTejun Heo { 720137d3edbSTejun Heo sg_miter_stop(miter); 721137d3edbSTejun Heo 7224225fc85SImre Deak /* 7234225fc85SImre Deak * Get to the next page if necessary. 7244225fc85SImre Deak * __remaining, __offset is adjusted by sg_miter_stop 7254225fc85SImre Deak */ 72611052004SAkinobu Mita if (!sg_miter_get_next_page(miter)) 72723c560a9STejun Heo return false; 7284225fc85SImre Deak 7292db76d7cSImre Deak miter->page = sg_page_iter_page(&miter->piter); 7304225fc85SImre Deak miter->consumed = miter->length = miter->__remaining; 731137d3edbSTejun Heo 732137d3edbSTejun Heo if (miter->__flags & SG_MITER_ATOMIC) 7334225fc85SImre Deak miter->addr = kmap_atomic(miter->page) + miter->__offset; 734137d3edbSTejun Heo else 7354225fc85SImre Deak miter->addr = kmap(miter->page) + miter->__offset; 736137d3edbSTejun Heo 737137d3edbSTejun Heo return true; 738137d3edbSTejun Heo } 739137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_next); 740137d3edbSTejun Heo 741137d3edbSTejun Heo /** 742137d3edbSTejun Heo * sg_miter_stop - stop mapping iteration 743137d3edbSTejun Heo * @miter: sg mapping iter to be stopped 744137d3edbSTejun Heo * 745137d3edbSTejun Heo * Description: 746137d3edbSTejun Heo * Stops mapping iterator @miter. @miter should have been started 7474ba6a2b2SMasahiro Yamada * using sg_miter_start(). A stopped iteration can be resumed by 7484ba6a2b2SMasahiro Yamada * calling sg_miter_next() on it. This is useful when resources (kmap) 7494ba6a2b2SMasahiro Yamada * need to be released during iteration. 750137d3edbSTejun Heo * 751137d3edbSTejun Heo * Context: 7528290e2d2STejun Heo * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care 7538290e2d2STejun Heo * otherwise. 754137d3edbSTejun Heo */ 755137d3edbSTejun Heo void sg_miter_stop(struct sg_mapping_iter *miter) 756137d3edbSTejun Heo { 757137d3edbSTejun Heo WARN_ON(miter->consumed > miter->length); 758137d3edbSTejun Heo 759137d3edbSTejun Heo /* drop resources from the last iteration */ 760137d3edbSTejun Heo if (miter->addr) { 761137d3edbSTejun Heo miter->__offset += miter->consumed; 7624225fc85SImre Deak miter->__remaining -= miter->consumed; 763137d3edbSTejun Heo 7643d77b50cSMing Lei if ((miter->__flags & SG_MITER_TO_SG) && 7653d77b50cSMing Lei !PageSlab(miter->page)) 7666de7e356SSebastian Andrzej Siewior flush_kernel_dcache_page(miter->page); 7676de7e356SSebastian Andrzej Siewior 768137d3edbSTejun Heo if (miter->__flags & SG_MITER_ATOMIC) { 7698290e2d2STejun Heo WARN_ON_ONCE(preemptible()); 770c3eede8eSCong Wang kunmap_atomic(miter->addr); 771137d3edbSTejun Heo } else 772f652c521SArjan van de Ven kunmap(miter->page); 773137d3edbSTejun Heo 774137d3edbSTejun Heo miter->page = NULL; 775137d3edbSTejun Heo miter->addr = NULL; 776137d3edbSTejun Heo miter->length = 0; 777137d3edbSTejun Heo miter->consumed = 0; 778137d3edbSTejun Heo } 779137d3edbSTejun Heo } 780137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_stop); 781137d3edbSTejun Heo 782137d3edbSTejun Heo /** 783b1adaf65SFUJITA Tomonori * sg_copy_buffer - Copy data between a linear buffer and an SG list 784b1adaf65SFUJITA Tomonori * @sgl: The SG list 785b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 786b1adaf65SFUJITA Tomonori * @buf: Where to copy from 787b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 788df642ceaSAkinobu Mita * @skip: Number of bytes to skip before copying 789df642ceaSAkinobu Mita * @to_buffer: transfer direction (true == from an sg list to a 790df642ceaSAkinobu Mita * buffer, false == from a buffer to an sg list 791b1adaf65SFUJITA Tomonori * 792b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 793b1adaf65SFUJITA Tomonori * 794b1adaf65SFUJITA Tomonori **/ 795386ecb12SDave Gordon size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, 796386ecb12SDave Gordon size_t buflen, off_t skip, bool to_buffer) 797b1adaf65SFUJITA Tomonori { 798137d3edbSTejun Heo unsigned int offset = 0; 799137d3edbSTejun Heo struct sg_mapping_iter miter; 8006de7e356SSebastian Andrzej Siewior unsigned int sg_flags = SG_MITER_ATOMIC; 801b1adaf65SFUJITA Tomonori 8026de7e356SSebastian Andrzej Siewior if (to_buffer) 8036de7e356SSebastian Andrzej Siewior sg_flags |= SG_MITER_FROM_SG; 8046de7e356SSebastian Andrzej Siewior else 8056de7e356SSebastian Andrzej Siewior sg_flags |= SG_MITER_TO_SG; 8066de7e356SSebastian Andrzej Siewior 8076de7e356SSebastian Andrzej Siewior sg_miter_start(&miter, sgl, nents, sg_flags); 808b1adaf65SFUJITA Tomonori 809df642ceaSAkinobu Mita if (!sg_miter_skip(&miter, skip)) 810df642ceaSAkinobu Mita return false; 811df642ceaSAkinobu Mita 8121d5210efSGilad Ben-Yossef while ((offset < buflen) && sg_miter_next(&miter)) { 813137d3edbSTejun Heo unsigned int len; 814b1adaf65SFUJITA Tomonori 815137d3edbSTejun Heo len = min(miter.length, buflen - offset); 816b1adaf65SFUJITA Tomonori 817b1adaf65SFUJITA Tomonori if (to_buffer) 818137d3edbSTejun Heo memcpy(buf + offset, miter.addr, len); 8196de7e356SSebastian Andrzej Siewior else 820137d3edbSTejun Heo memcpy(miter.addr, buf + offset, len); 821b1adaf65SFUJITA Tomonori 822137d3edbSTejun Heo offset += len; 823b1adaf65SFUJITA Tomonori } 824b1adaf65SFUJITA Tomonori 825137d3edbSTejun Heo sg_miter_stop(&miter); 826b1adaf65SFUJITA Tomonori 827137d3edbSTejun Heo return offset; 828b1adaf65SFUJITA Tomonori } 829386ecb12SDave Gordon EXPORT_SYMBOL(sg_copy_buffer); 830b1adaf65SFUJITA Tomonori 831b1adaf65SFUJITA Tomonori /** 832b1adaf65SFUJITA Tomonori * sg_copy_from_buffer - Copy from a linear buffer to an SG list 833b1adaf65SFUJITA Tomonori * @sgl: The SG list 834b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 835b1adaf65SFUJITA Tomonori * @buf: Where to copy from 836b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 837b1adaf65SFUJITA Tomonori * 838b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 839b1adaf65SFUJITA Tomonori * 840b1adaf65SFUJITA Tomonori **/ 841b1adaf65SFUJITA Tomonori size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, 8422a1bf8f9SDave Gordon const void *buf, size_t buflen) 843b1adaf65SFUJITA Tomonori { 8442a1bf8f9SDave Gordon return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false); 845b1adaf65SFUJITA Tomonori } 846b1adaf65SFUJITA Tomonori EXPORT_SYMBOL(sg_copy_from_buffer); 847b1adaf65SFUJITA Tomonori 848b1adaf65SFUJITA Tomonori /** 849b1adaf65SFUJITA Tomonori * sg_copy_to_buffer - Copy from an SG list to a linear buffer 850b1adaf65SFUJITA Tomonori * @sgl: The SG list 851b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 852b1adaf65SFUJITA Tomonori * @buf: Where to copy to 853b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 854b1adaf65SFUJITA Tomonori * 855b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 856b1adaf65SFUJITA Tomonori * 857b1adaf65SFUJITA Tomonori **/ 858b1adaf65SFUJITA Tomonori size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, 859b1adaf65SFUJITA Tomonori void *buf, size_t buflen) 860b1adaf65SFUJITA Tomonori { 861df642ceaSAkinobu Mita return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); 862b1adaf65SFUJITA Tomonori } 863b1adaf65SFUJITA Tomonori EXPORT_SYMBOL(sg_copy_to_buffer); 864df642ceaSAkinobu Mita 865df642ceaSAkinobu Mita /** 866df642ceaSAkinobu Mita * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list 867df642ceaSAkinobu Mita * @sgl: The SG list 868df642ceaSAkinobu Mita * @nents: Number of SG entries 869df642ceaSAkinobu Mita * @buf: Where to copy from 870df642ceaSAkinobu Mita * @buflen: The number of bytes to copy 8714dc7daf8SDave Gordon * @skip: Number of bytes to skip before copying 872df642ceaSAkinobu Mita * 873df642ceaSAkinobu Mita * Returns the number of copied bytes. 874df642ceaSAkinobu Mita * 875df642ceaSAkinobu Mita **/ 876df642ceaSAkinobu Mita size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, 8772a1bf8f9SDave Gordon const void *buf, size_t buflen, off_t skip) 878df642ceaSAkinobu Mita { 8792a1bf8f9SDave Gordon return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false); 880df642ceaSAkinobu Mita } 881df642ceaSAkinobu Mita EXPORT_SYMBOL(sg_pcopy_from_buffer); 882df642ceaSAkinobu Mita 883df642ceaSAkinobu Mita /** 884df642ceaSAkinobu Mita * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer 885df642ceaSAkinobu Mita * @sgl: The SG list 886df642ceaSAkinobu Mita * @nents: Number of SG entries 887df642ceaSAkinobu Mita * @buf: Where to copy to 888df642ceaSAkinobu Mita * @buflen: The number of bytes to copy 8894dc7daf8SDave Gordon * @skip: Number of bytes to skip before copying 890df642ceaSAkinobu Mita * 891df642ceaSAkinobu Mita * Returns the number of copied bytes. 892df642ceaSAkinobu Mita * 893df642ceaSAkinobu Mita **/ 894df642ceaSAkinobu Mita size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, 895df642ceaSAkinobu Mita void *buf, size_t buflen, off_t skip) 896df642ceaSAkinobu Mita { 897df642ceaSAkinobu Mita return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); 898df642ceaSAkinobu Mita } 899df642ceaSAkinobu Mita EXPORT_SYMBOL(sg_pcopy_to_buffer); 9000945e569SJohannes Thumshirn 9010945e569SJohannes Thumshirn /** 9020945e569SJohannes Thumshirn * sg_zero_buffer - Zero-out a part of a SG list 9030945e569SJohannes Thumshirn * @sgl: The SG list 9040945e569SJohannes Thumshirn * @nents: Number of SG entries 9050945e569SJohannes Thumshirn * @buflen: The number of bytes to zero out 9060945e569SJohannes Thumshirn * @skip: Number of bytes to skip before zeroing 9070945e569SJohannes Thumshirn * 9080945e569SJohannes Thumshirn * Returns the number of bytes zeroed. 9090945e569SJohannes Thumshirn **/ 9100945e569SJohannes Thumshirn size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, 9110945e569SJohannes Thumshirn size_t buflen, off_t skip) 9120945e569SJohannes Thumshirn { 9130945e569SJohannes Thumshirn unsigned int offset = 0; 9140945e569SJohannes Thumshirn struct sg_mapping_iter miter; 9150945e569SJohannes Thumshirn unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; 9160945e569SJohannes Thumshirn 9170945e569SJohannes Thumshirn sg_miter_start(&miter, sgl, nents, sg_flags); 9180945e569SJohannes Thumshirn 9190945e569SJohannes Thumshirn if (!sg_miter_skip(&miter, skip)) 9200945e569SJohannes Thumshirn return false; 9210945e569SJohannes Thumshirn 9220945e569SJohannes Thumshirn while (offset < buflen && sg_miter_next(&miter)) { 9230945e569SJohannes Thumshirn unsigned int len; 9240945e569SJohannes Thumshirn 9250945e569SJohannes Thumshirn len = min(miter.length, buflen - offset); 9260945e569SJohannes Thumshirn memset(miter.addr, 0, len); 9270945e569SJohannes Thumshirn 9280945e569SJohannes Thumshirn offset += len; 9290945e569SJohannes Thumshirn } 9300945e569SJohannes Thumshirn 9310945e569SJohannes Thumshirn sg_miter_stop(&miter); 9320945e569SJohannes Thumshirn return offset; 9330945e569SJohannes Thumshirn } 9340945e569SJohannes Thumshirn EXPORT_SYMBOL(sg_zero_buffer); 935