iov_iter.c revision 91f79c43d1b54d7154b118860d81b39bad07dfff
14f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/export.h> 24f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/uio.h> 34f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/pagemap.h> 491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro#include <linux/slab.h> 591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro#include <linux/vmalloc.h> 64f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 74f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 84f18cd317a118c28482f97303600a2fe2ada6c79Al Viro struct iov_iter *i) 94f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 104f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t skip, copy, left, wanted; 114f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov; 124f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf; 134f18cd317a118c28482f97303600a2fe2ada6c79Al Viro void *kaddr, *from; 144f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 154f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(bytes > i->count)) 164f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes = i->count; 174f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 184f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(!bytes)) 194f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return 0; 204f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 214f18cd317a118c28482f97303600a2fe2ada6c79Al Viro wanted = bytes; 224f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov = i->iov; 234f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = i->iov_offset; 244f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base + skip; 254f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - skip); 264f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 274f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (!fault_in_pages_writeable(buf, copy)) { 284f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap_atomic(page); 294f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from = kaddr + offset; 304f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 314f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* first chunk, usually the only one */ 324f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user_inatomic(buf, from, copy); 334f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 344f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip += copy; 354f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 364f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 374f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 384f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (unlikely(!left && bytes)) { 394f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 404f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base; 414f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len); 424f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user_inatomic(buf, from, copy); 434f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 444f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = copy; 454f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 464f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 474f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 484f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(!bytes)) { 494f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 504f18cd317a118c28482f97303600a2fe2ada6c79Al Viro goto done; 514f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 524f18cd317a118c28482f97303600a2fe2ada6c79Al Viro offset = from - kaddr; 534f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf += copy; 544f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 554f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - skip); 564f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 574f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* Too bad - revert to non-atomic kmap */ 584f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap(page); 594f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from = kaddr + offset; 604f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user(buf, from, copy); 614f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 624f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip += copy; 634f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 644f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 654f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (unlikely(!left && bytes)) { 664f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 674f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base; 684f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len); 694f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user(buf, from, copy); 704f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 714f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = copy; 724f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 734f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 744f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 754f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap(page); 764f18cd317a118c28482f97303600a2fe2ada6c79Al Virodone: 774f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= wanted - bytes; 784f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->nr_segs -= iov - i->iov; 794f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov = iov; 804f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset = skip; 814f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return wanted - bytes; 824f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 834f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(copy_page_to_iter); 844f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 854f18cd317a118c28482f97303600a2fe2ada6c79Al Virostatic size_t __iovec_copy_from_user_inatomic(char *vaddr, 864f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov, size_t base, size_t bytes) 874f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 884f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t copied = 0, left = 0; 894f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 904f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (bytes) { 914f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = iov->iov_base + base; 924f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int copy = min(bytes, iov->iov_len - base); 934f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 944f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base = 0; 954f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_from_user_inatomic(vaddr, buf, copy); 964f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied += copy; 974f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 984f18cd317a118c28482f97303600a2fe2ada6c79Al Viro vaddr += copy; 994f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 1004f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1014f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(left)) 1024f18cd317a118c28482f97303600a2fe2ada6c79Al Viro break; 1034f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1044f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return copied - left; 1054f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1064f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1074f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 1084f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Copy as much as we can into the page and return the number of bytes which 1094f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * were successfully copied. If a fault is encountered then return the number of 1104f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * bytes which were copied. 1114f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1124f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t iov_iter_copy_from_user_atomic(struct page *page, 1134f18cd317a118c28482f97303600a2fe2ada6c79Al Viro struct iov_iter *i, unsigned long offset, size_t bytes) 1144f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1154f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char *kaddr; 1164f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t copied; 1174f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1184f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap_atomic(page); 1194f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(i->nr_segs == 1)) { 1204f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int left; 1214f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = i->iov->iov_base + i->iov_offset; 1224f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); 1234f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied = bytes - left; 1244f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } else { 1254f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied = __iovec_copy_from_user_inatomic(kaddr + offset, 1264f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov, i->iov_offset, bytes); 1274f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1284f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 1294f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1304f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return copied; 1314f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1324f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_copy_from_user_atomic); 1334f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1344f18cd317a118c28482f97303600a2fe2ada6c79Al Virovoid iov_iter_advance(struct iov_iter *i, size_t bytes) 1354f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1364f18cd317a118c28482f97303600a2fe2ada6c79Al Viro BUG_ON(i->count < bytes); 1374f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1384f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(i->nr_segs == 1)) { 1394f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset += bytes; 1404f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= bytes; 1414f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } else { 1424f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov = i->iov; 1434f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t base = i->iov_offset; 1444f18cd317a118c28482f97303600a2fe2ada6c79Al Viro unsigned long nr_segs = i->nr_segs; 1454f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1464f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* 1474f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * The !iov->iov_len check ensures we skip over unlikely 1484f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * zero-length segments (without overruning the iovec). 1494f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1504f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (bytes || unlikely(i->count && !iov->iov_len)) { 1514f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int copy; 1524f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1534f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - base); 1544f18cd317a118c28482f97303600a2fe2ada6c79Al Viro BUG_ON(!i->count || i->count < copy); 1554f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= copy; 1564f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 1574f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base += copy; 1584f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (iov->iov_len == base) { 1594f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 1604f18cd317a118c28482f97303600a2fe2ada6c79Al Viro nr_segs--; 1614f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base = 0; 1624f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1634f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1644f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov = iov; 1654f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset = base; 1664f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->nr_segs = nr_segs; 1674f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1684f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1694f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_advance); 1704f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1714f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 1724f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Fault in the first iovec of the given iov_iter, to a maximum length 1734f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * of bytes. Returns 0 on success, or non-zero if the memory could not be 1744f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * accessed (ie. because it is an invalid address). 1754f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * 1764f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * writev-intensive code may want this to prefault several iovecs -- that 1774f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * would be possible (callers must not rely on the fact that _only_ the 1784f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * first iovec will be faulted with the current implementation). 1794f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1804f18cd317a118c28482f97303600a2fe2ada6c79Al Viroint iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) 1814f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1824f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = i->iov->iov_base + i->iov_offset; 1834f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes = min(bytes, i->iov->iov_len - i->iov_offset); 1844f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return fault_in_pages_readable(buf, bytes); 1854f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1864f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_fault_in_readable); 1874f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1884f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 1894f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Return the count of just the current iov_iter segment. 1904f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1914f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t iov_iter_single_seg_count(const struct iov_iter *i) 1924f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1934f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov = i->iov; 1944f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (i->nr_segs == 1) 1954f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return i->count; 1964f18cd317a118c28482f97303600a2fe2ada6c79Al Viro else 1974f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return min(i->count, iov->iov_len - i->iov_offset); 1984f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1994f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_single_seg_count); 200886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 201886a39115005ced8b15ab067c9c2a8d546b40a5eAl Virounsigned long iov_iter_alignment(const struct iov_iter *i) 202886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro{ 203886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro const struct iovec *iov = i->iov; 204886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro unsigned long res; 205886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size_t size = i->count; 206886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size_t n; 207886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 208886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro if (!size) 209886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return 0; 210886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 211886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res = (unsigned long)iov->iov_base + i->iov_offset; 212886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro n = iov->iov_len - i->iov_offset; 213886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro if (n >= size) 214886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return res | size; 215886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size -= n; 216886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= n; 217886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro while (size > (++iov)->iov_len) { 218886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= (unsigned long)iov->iov_base | iov->iov_len; 219886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size -= iov->iov_len; 220886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro } 221886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= (unsigned long)iov->iov_base | size; 222886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return res; 223886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro} 224886a39115005ced8b15ab067c9c2a8d546b40a5eAl ViroEXPORT_SYMBOL(iov_iter_alignment); 22571d8e532b1549a478e6a6a8a44f309d050294d00Al Viro 22671d8e532b1549a478e6a6a8a44f309d050294d00Al Virovoid iov_iter_init(struct iov_iter *i, int direction, 22771d8e532b1549a478e6a6a8a44f309d050294d00Al Viro const struct iovec *iov, unsigned long nr_segs, 22871d8e532b1549a478e6a6a8a44f309d050294d00Al Viro size_t count) 22971d8e532b1549a478e6a6a8a44f309d050294d00Al Viro{ 23071d8e532b1549a478e6a6a8a44f309d050294d00Al Viro /* It will get better. Eventually... */ 23171d8e532b1549a478e6a6a8a44f309d050294d00Al Viro if (segment_eq(get_fs(), KERNEL_DS)) 23271d8e532b1549a478e6a6a8a44f309d050294d00Al Viro direction |= REQ_KERNEL; 23371d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->type = direction; 23471d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->iov = iov; 23571d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->nr_segs = nr_segs; 23671d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->iov_offset = 0; 23771d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->count = count; 23871d8e532b1549a478e6a6a8a44f309d050294d00Al Viro} 23971d8e532b1549a478e6a6a8a44f309d050294d00Al ViroEXPORT_SYMBOL(iov_iter_init); 2407b2c99d15559e285384c742db52316802e24b0bdAl Viro 2417b2c99d15559e285384c742db52316802e24b0bdAl Virossize_t iov_iter_get_pages(struct iov_iter *i, 2427b2c99d15559e285384c742db52316802e24b0bdAl Viro struct page **pages, size_t maxsize, 2437b2c99d15559e285384c742db52316802e24b0bdAl Viro size_t *start) 2447b2c99d15559e285384c742db52316802e24b0bdAl Viro{ 2457b2c99d15559e285384c742db52316802e24b0bdAl Viro size_t offset = i->iov_offset; 2467b2c99d15559e285384c742db52316802e24b0bdAl Viro const struct iovec *iov = i->iov; 2477b2c99d15559e285384c742db52316802e24b0bdAl Viro size_t len; 2487b2c99d15559e285384c742db52316802e24b0bdAl Viro unsigned long addr; 2497b2c99d15559e285384c742db52316802e24b0bdAl Viro int n; 2507b2c99d15559e285384c742db52316802e24b0bdAl Viro int res; 2517b2c99d15559e285384c742db52316802e24b0bdAl Viro 2527b2c99d15559e285384c742db52316802e24b0bdAl Viro len = iov->iov_len - offset; 2537b2c99d15559e285384c742db52316802e24b0bdAl Viro if (len > i->count) 2547b2c99d15559e285384c742db52316802e24b0bdAl Viro len = i->count; 2557b2c99d15559e285384c742db52316802e24b0bdAl Viro if (len > maxsize) 2567b2c99d15559e285384c742db52316802e24b0bdAl Viro len = maxsize; 2577b2c99d15559e285384c742db52316802e24b0bdAl Viro addr = (unsigned long)iov->iov_base + offset; 2587b2c99d15559e285384c742db52316802e24b0bdAl Viro len += *start = addr & (PAGE_SIZE - 1); 2597b2c99d15559e285384c742db52316802e24b0bdAl Viro addr &= ~(PAGE_SIZE - 1); 2607b2c99d15559e285384c742db52316802e24b0bdAl Viro n = (len + PAGE_SIZE - 1) / PAGE_SIZE; 2617b2c99d15559e285384c742db52316802e24b0bdAl Viro res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages); 2627b2c99d15559e285384c742db52316802e24b0bdAl Viro if (unlikely(res < 0)) 2637b2c99d15559e285384c742db52316802e24b0bdAl Viro return res; 2647b2c99d15559e285384c742db52316802e24b0bdAl Viro return (res == n ? len : res * PAGE_SIZE) - *start; 2657b2c99d15559e285384c742db52316802e24b0bdAl Viro} 2667b2c99d15559e285384c742db52316802e24b0bdAl ViroEXPORT_SYMBOL(iov_iter_get_pages); 267f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro 26891f79c43d1b54d7154b118860d81b39bad07dfffAl Virossize_t iov_iter_get_pages_alloc(struct iov_iter *i, 26991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro struct page ***pages, size_t maxsize, 27091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro size_t *start) 27191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro{ 27291f79c43d1b54d7154b118860d81b39bad07dfffAl Viro size_t offset = i->iov_offset; 27391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro const struct iovec *iov = i->iov; 27491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro size_t len; 27591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro unsigned long addr; 27691f79c43d1b54d7154b118860d81b39bad07dfffAl Viro void *p; 27791f79c43d1b54d7154b118860d81b39bad07dfffAl Viro int n; 27891f79c43d1b54d7154b118860d81b39bad07dfffAl Viro int res; 27991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 28091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len = iov->iov_len - offset; 28191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (len > i->count) 28291f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len = i->count; 28391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (len > maxsize) 28491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len = maxsize; 28591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro addr = (unsigned long)iov->iov_base + offset; 28691f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len += *start = addr & (PAGE_SIZE - 1); 28791f79c43d1b54d7154b118860d81b39bad07dfffAl Viro addr &= ~(PAGE_SIZE - 1); 28891f79c43d1b54d7154b118860d81b39bad07dfffAl Viro n = (len + PAGE_SIZE - 1) / PAGE_SIZE; 28991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 29091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro p = kmalloc(n * sizeof(struct page *), GFP_KERNEL); 29191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (!p) 29291f79c43d1b54d7154b118860d81b39bad07dfffAl Viro p = vmalloc(n * sizeof(struct page *)); 29391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (!p) 29491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro return -ENOMEM; 29591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 29691f79c43d1b54d7154b118860d81b39bad07dfffAl Viro res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p); 29791f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (unlikely(res < 0)) { 29891f79c43d1b54d7154b118860d81b39bad07dfffAl Viro kvfree(p); 29991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro return res; 30091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro } 30191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro *pages = p; 30291f79c43d1b54d7154b118860d81b39bad07dfffAl Viro return (res == n ? len : res * PAGE_SIZE) - *start; 30391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro} 30491f79c43d1b54d7154b118860d81b39bad07dfffAl ViroEXPORT_SYMBOL(iov_iter_get_pages_alloc); 30591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 306f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viroint iov_iter_npages(const struct iov_iter *i, int maxpages) 307f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro{ 308f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size_t offset = i->iov_offset; 309f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size_t size = i->count; 310f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro const struct iovec *iov = i->iov; 311f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro int npages = 0; 312f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro int n; 313f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro 314f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro for (n = 0; size && n < i->nr_segs; n++, iov++) { 315f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro unsigned long addr = (unsigned long)iov->iov_base + offset; 316f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size_t len = iov->iov_len - offset; 317f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro offset = 0; 318f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro if (unlikely(!len)) /* empty segment */ 319f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro continue; 320f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro if (len > size) 321f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro len = size; 322f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE 323f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro - addr / PAGE_SIZE; 324f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro if (npages >= maxpages) /* don't bother going further */ 325f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro return maxpages; 326f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size -= len; 327f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro offset = 0; 328f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro } 329f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro return min(npages, maxpages); 330f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro} 331f67da30c1d5fc9e341bc8121708874bfd7b31e45Al ViroEXPORT_SYMBOL(iov_iter_npages); 332